[PATCH] libata: Conditionally set host->max_cmd_len

[deliverable/linux.git] / drivers / scsi / libata-core.c

/*
 *  libata-core.c - helper library for ATA
 *
 *  Maintained by:  Jeff Garzik <jgarzik@pobox.com>
 *                  Please ALWAYS copy linux-ide@vger.kernel.org
 *                  on emails.
 *
 *  Copyright 2003-2004 Red Hat, Inc.  All rights reserved.
 *  Copyright 2003-2004 Jeff Garzik
 *
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 *  libata documentation is available via 'make {ps|pdf}docs',
 *  as Documentation/DocBook/libata.*
 *
 *  Hardware documentation available from http://www.t13.org/ and
 *  http://www.sata-io.org/
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/spinlock.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/completion.h>
#include <linux/suspend.h>
#include <linux/workqueue.h>
#include <linux/jiffies.h>
#include <linux/scatterlist.h>
#include <scsi/scsi.h>
#include "scsi_priv.h"
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
#include <linux/libata.h>
#include <asm/io.h>
#include <asm/semaphore.h>
#include <asm/byteorder.h>

#include "libata.h"

/* debounce timing parameters in msecs { interval, duration, timeout } */
const unsigned long sata_deb_timing_boot[]              = {   5,  100, 2000 };
const unsigned long sata_deb_timing_eh[]                = {  25,  500, 2000 };
const unsigned long sata_deb_timing_before_fsrst[]      = { 100, 2000, 5000 };

static unsigned int ata_dev_init_params(struct ata_device *dev,
                                        u16 heads, u16 sectors);
static unsigned int ata_dev_set_xfermode(struct ata_device *dev);
static void ata_dev_xfermask(struct ata_device *dev);

static unsigned int ata_unique_id = 1;
static struct workqueue_struct *ata_wq;

struct workqueue_struct *ata_aux_wq;

int atapi_enabled = 1;
module_param(atapi_enabled, int, 0444);
MODULE_PARM_DESC(atapi_enabled, "Enable discovery of ATAPI devices (0=off, 1=on)");

int atapi_dmadir = 0;
module_param(atapi_dmadir, int, 0444);
MODULE_PARM_DESC(atapi_dmadir, "Enable ATAPI DMADIR bridge support (0=off, 1=on)");

int libata_fua = 0;
module_param_named(fua, libata_fua, int, 0444);
MODULE_PARM_DESC(fua, "FUA support (0=off, 1=on)");

static int ata_probe_timeout = ATA_TMOUT_INTERNAL / HZ;
module_param(ata_probe_timeout, int, 0444);
MODULE_PARM_DESC(ata_probe_timeout, "Set ATA probing timeout (seconds)");

MODULE_AUTHOR("Jeff Garzik");
MODULE_DESCRIPTION("Library module for ATA devices");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);


/**
 *      ata_tf_to_fis - Convert ATA taskfile to SATA FIS structure
 *      @tf: Taskfile to convert
 *      @fis: Buffer into which data will output
 *      @pmp: Port multiplier port
 *
 *      Converts a standard ATA taskfile to a Serial ATA
 *      FIS structure (Register - Host to Device).
 *
 *      LOCKING:
 *      Inherited from caller.
 */

void ata_tf_to_fis(const struct ata_taskfile *tf, u8 *fis, u8 pmp)
{
        fis[0] = 0x27;  /* Register - Host to Device FIS */
        fis[1] = (pmp & 0xf) | (1 << 7); /* Port multiplier number,
                                            bit 7 indicates Command FIS */
        fis[2] = tf->command;
        fis[3] = tf->feature;

        fis[4] = tf->lbal;
        fis[5] = tf->lbam;
        fis[6] = tf->lbah;
        fis[7] = tf->device;

        fis[8] = tf->hob_lbal;
        fis[9] = tf->hob_lbam;
        fis[10] = tf->hob_lbah;
        fis[11] = tf->hob_feature;

        fis[12] = tf->nsect;
        fis[13] = tf->hob_nsect;
        fis[14] = 0;
        fis[15] = tf->ctl;

        fis[16] = 0;
        fis[17] = 0;
        fis[18] = 0;
        fis[19] = 0;
}

/**
 *      ata_tf_from_fis - Convert SATA FIS to ATA taskfile
 *      @fis: Buffer from which data will be input
 *      @tf: Taskfile to output
 *
 *      Converts a serial ATA FIS structure to a standard ATA taskfile.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

void ata_tf_from_fis(const u8 *fis, struct ata_taskfile *tf)
{
        tf->command     = fis[2];       /* status */
        tf->feature     = fis[3];       /* error */

        tf->lbal        = fis[4];
        tf->lbam        = fis[5];
        tf->lbah        = fis[6];
        tf->device      = fis[7];

        tf->hob_lbal    = fis[8];
        tf->hob_lbam    = fis[9];
        tf->hob_lbah    = fis[10];

        tf->nsect       = fis[12];
        tf->hob_nsect   = fis[13];
}

static const u8 ata_rw_cmds[] = {
        /* pio multi */
        ATA_CMD_READ_MULTI,
        ATA_CMD_WRITE_MULTI,
        ATA_CMD_READ_MULTI_EXT,
        ATA_CMD_WRITE_MULTI_EXT,
        0,
        0,
        0,
        ATA_CMD_WRITE_MULTI_FUA_EXT,
        /* pio */
        ATA_CMD_PIO_READ,
        ATA_CMD_PIO_WRITE,
        ATA_CMD_PIO_READ_EXT,
        ATA_CMD_PIO_WRITE_EXT,
        0,
        0,
        0,
        0,
        /* dma */
        ATA_CMD_READ,
        ATA_CMD_WRITE,
        ATA_CMD_READ_EXT,
        ATA_CMD_WRITE_EXT,
        0,
        0,
        0,
        ATA_CMD_WRITE_FUA_EXT
};

/**
 *      ata_rwcmd_protocol - set taskfile r/w commands and protocol
 *      @qc: command to examine and configure
 *
 *      Examine the device configuration and tf->flags to calculate
 *      the proper read/write commands and protocol to use.
 *
 *      LOCKING:
 *      caller.
 */
int ata_rwcmd_protocol(struct ata_queued_cmd *qc)
{
        struct ata_taskfile *tf = &qc->tf;
        struct ata_device *dev = qc->dev;
        u8 cmd;

        int index, fua, lba48, write;

        fua = (tf->flags & ATA_TFLAG_FUA) ? 4 : 0;
        lba48 = (tf->flags & ATA_TFLAG_LBA48) ? 2 : 0;
        write = (tf->flags & ATA_TFLAG_WRITE) ? 1 : 0;

        if (dev->flags & ATA_DFLAG_PIO) {
                tf->protocol = ATA_PROT_PIO;
                index = dev->multi_count ? 0 : 8;
        } else if (lba48 && (qc->ap->flags & ATA_FLAG_PIO_LBA48)) {
                /* Unable to use DMA due to host limitation */
                tf->protocol = ATA_PROT_PIO;
                index = dev->multi_count ? 0 : 8;
        } else {
                tf->protocol = ATA_PROT_DMA;
                index = 16;
        }

        cmd = ata_rw_cmds[index + fua + lba48 + write];
        if (cmd) {
                tf->command = cmd;
                return 0;
        }
        return -1;
}

/**
 *      ata_pack_xfermask - Pack pio, mwdma and udma masks into xfer_mask
 *      @pio_mask: pio_mask
 *      @mwdma_mask: mwdma_mask
 *      @udma_mask: udma_mask
 *
 *      Pack @pio_mask, @mwdma_mask and @udma_mask into a single
 *      unsigned int xfer_mask.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Packed xfer_mask.
 */
static unsigned int ata_pack_xfermask(unsigned int pio_mask,
                                      unsigned int mwdma_mask,
                                      unsigned int udma_mask)
{
        return ((pio_mask << ATA_SHIFT_PIO) & ATA_MASK_PIO) |
                ((mwdma_mask << ATA_SHIFT_MWDMA) & ATA_MASK_MWDMA) |
                ((udma_mask << ATA_SHIFT_UDMA) & ATA_MASK_UDMA);
}

/**
 *      ata_unpack_xfermask - Unpack xfer_mask into pio, mwdma and udma masks
 *      @xfer_mask: xfer_mask to unpack
 *      @pio_mask: resulting pio_mask
 *      @mwdma_mask: resulting mwdma_mask
 *      @udma_mask: resulting udma_mask
 *
 *      Unpack @xfer_mask into @pio_mask, @mwdma_mask and @udma_mask.
 *      Any NULL distination masks will be ignored.
 */
static void ata_unpack_xfermask(unsigned int xfer_mask,
                                unsigned int *pio_mask,
                                unsigned int *mwdma_mask,
                                unsigned int *udma_mask)
{
        if (pio_mask)
                *pio_mask = (xfer_mask & ATA_MASK_PIO) >> ATA_SHIFT_PIO;
        if (mwdma_mask)
                *mwdma_mask = (xfer_mask & ATA_MASK_MWDMA) >> ATA_SHIFT_MWDMA;
        if (udma_mask)
                *udma_mask = (xfer_mask & ATA_MASK_UDMA) >> ATA_SHIFT_UDMA;
}

static const struct ata_xfer_ent {
        int shift, bits;
        u8 base;
} ata_xfer_tbl[] = {
        { ATA_SHIFT_PIO, ATA_BITS_PIO, XFER_PIO_0 },
        { ATA_SHIFT_MWDMA, ATA_BITS_MWDMA, XFER_MW_DMA_0 },
        { ATA_SHIFT_UDMA, ATA_BITS_UDMA, XFER_UDMA_0 },
        { -1, },
};

/**
 *      ata_xfer_mask2mode - Find matching XFER_* for the given xfer_mask
 *      @xfer_mask: xfer_mask of interest
 *
 *      Return matching XFER_* value for @xfer_mask.  Only the highest
 *      bit of @xfer_mask is considered.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Matching XFER_* value, 0 if no match found.
 */
static u8 ata_xfer_mask2mode(unsigned int xfer_mask)
{
        int highbit = fls(xfer_mask) - 1;
        const struct ata_xfer_ent *ent;

        for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
                if (highbit >= ent->shift && highbit < ent->shift + ent->bits)
                        return ent->base + highbit - ent->shift;
        return 0;
}

/**
 *      ata_xfer_mode2mask - Find matching xfer_mask for XFER_*
 *      @xfer_mode: XFER_* of interest
 *
 *      Return matching xfer_mask for @xfer_mode.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Matching xfer_mask, 0 if no match found.
 */
static unsigned int ata_xfer_mode2mask(u8 xfer_mode)
{
        const struct ata_xfer_ent *ent;

        for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
                if (xfer_mode >= ent->base && xfer_mode < ent->base + ent->bits)
                        return 1 << (ent->shift + xfer_mode - ent->base);
        return 0;
}

/**
 *      ata_xfer_mode2shift - Find matching xfer_shift for XFER_*
 *      @xfer_mode: XFER_* of interest
 *
 *      Return matching xfer_shift for @xfer_mode.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Matching xfer_shift, -1 if no match found.
 */
static int ata_xfer_mode2shift(unsigned int xfer_mode)
{
        const struct ata_xfer_ent *ent;

        for (ent = ata_xfer_tbl; ent->shift >= 0; ent++)
                if (xfer_mode >= ent->base && xfer_mode < ent->base + ent->bits)
                        return ent->shift;
        return -1;
}

/**
 *      ata_mode_string - convert xfer_mask to string
 *      @xfer_mask: mask of bits supported; only highest bit counts.
 *
 *      Determine string which represents the highest speed
 *      (highest bit in @modemask).
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Constant C string representing highest speed listed in
 *      @mode_mask, or the constant C string "<n/a>".
 */
static const char *ata_mode_string(unsigned int xfer_mask)
{
        static const char * const xfer_mode_str[] = {
                "PIO0",
                "PIO1",
                "PIO2",
                "PIO3",
                "PIO4",
                "MWDMA0",
                "MWDMA1",
                "MWDMA2",
                "UDMA/16",
                "UDMA/25",
                "UDMA/33",
                "UDMA/44",
                "UDMA/66",
                "UDMA/100",
                "UDMA/133",
                "UDMA7",
        };
        int highbit;

        highbit = fls(xfer_mask) - 1;
        if (highbit >= 0 && highbit < ARRAY_SIZE(xfer_mode_str))
                return xfer_mode_str[highbit];
        return "<n/a>";
}

static const char *sata_spd_string(unsigned int spd)
{
        static const char * const spd_str[] = {
                "1.5 Gbps",
                "3.0 Gbps",
        };

        if (spd == 0 || (spd - 1) >= ARRAY_SIZE(spd_str))
                return "<unknown>";
        return spd_str[spd - 1];
}

void ata_dev_disable(struct ata_device *dev)
{
        if (ata_dev_enabled(dev) && ata_msg_drv(dev->ap)) {
                ata_dev_printk(dev, KERN_WARNING, "disabled\n");
                dev->class++;
        }
}

/**
 *      ata_pio_devchk - PATA device presence detection
 *      @ap: ATA channel to examine
 *      @device: Device to examine (starting at zero)
 *
 *      This technique was originally described in
 *      Hale Landis's ATADRVR (www.ata-atapi.com), and
 *      later found its way into the ATA/ATAPI spec.
 *
 *      Write a pattern to the ATA shadow registers,
 *      and if a device is present, it will respond by
 *      correctly storing and echoing back the
 *      ATA shadow register contents.
 *
 *      LOCKING:
 *      caller.
 */

static unsigned int ata_pio_devchk(struct ata_port *ap,
                                   unsigned int device)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        u8 nsect, lbal;

        ap->ops->dev_select(ap, device);

        outb(0x55, ioaddr->nsect_addr);
        outb(0xaa, ioaddr->lbal_addr);

        outb(0xaa, ioaddr->nsect_addr);
        outb(0x55, ioaddr->lbal_addr);

        outb(0x55, ioaddr->nsect_addr);
        outb(0xaa, ioaddr->lbal_addr);

        nsect = inb(ioaddr->nsect_addr);
        lbal = inb(ioaddr->lbal_addr);

        if ((nsect == 0x55) && (lbal == 0xaa))
                return 1;       /* we found a device */

        return 0;               /* nothing found */
}

/**
 *      ata_mmio_devchk - PATA device presence detection
 *      @ap: ATA channel to examine
 *      @device: Device to examine (starting at zero)
 *
 *      This technique was originally described in
 *      Hale Landis's ATADRVR (www.ata-atapi.com), and
 *      later found its way into the ATA/ATAPI spec.
 *
 *      Write a pattern to the ATA shadow registers,
 *      and if a device is present, it will respond by
 *      correctly storing and echoing back the
 *      ATA shadow register contents.
 *
 *      LOCKING:
 *      caller.
 */

static unsigned int ata_mmio_devchk(struct ata_port *ap,
                                    unsigned int device)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        u8 nsect, lbal;

        ap->ops->dev_select(ap, device);

        writeb(0x55, (void __iomem *) ioaddr->nsect_addr);
        writeb(0xaa, (void __iomem *) ioaddr->lbal_addr);

        writeb(0xaa, (void __iomem *) ioaddr->nsect_addr);
        writeb(0x55, (void __iomem *) ioaddr->lbal_addr);

        writeb(0x55, (void __iomem *) ioaddr->nsect_addr);
        writeb(0xaa, (void __iomem *) ioaddr->lbal_addr);

        nsect = readb((void __iomem *) ioaddr->nsect_addr);
        lbal = readb((void __iomem *) ioaddr->lbal_addr);

        if ((nsect == 0x55) && (lbal == 0xaa))
                return 1;       /* we found a device */

        return 0;               /* nothing found */
}

/**
 *      ata_devchk - PATA device presence detection
 *      @ap: ATA channel to examine
 *      @device: Device to examine (starting at zero)
 *
 *      Dispatch ATA device presence detection, depending
 *      on whether we are using PIO or MMIO to talk to the
 *      ATA shadow registers.
 *
 *      LOCKING:
 *      caller.
 */

static unsigned int ata_devchk(struct ata_port *ap,
                                    unsigned int device)
{
        if (ap->flags & ATA_FLAG_MMIO)
                return ata_mmio_devchk(ap, device);
        return ata_pio_devchk(ap, device);
}

/**
 *      ata_dev_classify - determine device type based on ATA-spec signature
 *      @tf: ATA taskfile register set for device to be identified
 *
 *      Determine from taskfile register contents whether a device is
 *      ATA or ATAPI, as per "Signature and persistence" section
 *      of ATA/PI spec (volume 1, sect 5.14).
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Device type, %ATA_DEV_ATA, %ATA_DEV_ATAPI, or %ATA_DEV_UNKNOWN
 *      the event of failure.
 */

unsigned int ata_dev_classify(const struct ata_taskfile *tf)
{
        /* Apple's open source Darwin code hints that some devices only
         * put a proper signature into the LBA mid/high registers,
         * So, we only check those.  It's sufficient for uniqueness.
         */

        if (((tf->lbam == 0) && (tf->lbah == 0)) ||
            ((tf->lbam == 0x3c) && (tf->lbah == 0xc3))) {
                DPRINTK("found ATA device by sig\n");
                return ATA_DEV_ATA;
        }

        if (((tf->lbam == 0x14) && (tf->lbah == 0xeb)) ||
            ((tf->lbam == 0x69) && (tf->lbah == 0x96))) {
                DPRINTK("found ATAPI device by sig\n");
                return ATA_DEV_ATAPI;
        }

        DPRINTK("unknown device\n");
        return ATA_DEV_UNKNOWN;
}

/**
 *      ata_dev_try_classify - Parse returned ATA device signature
 *      @ap: ATA channel to examine
 *      @device: Device to examine (starting at zero)
 *      @r_err: Value of error register on completion
 *
 *      After an event -- SRST, E.D.D., or SATA COMRESET -- occurs,
 *      an ATA/ATAPI-defined set of values is placed in the ATA
 *      shadow registers, indicating the results of device detection
 *      and diagnostics.
 *
 *      Select the ATA device, and read the values from the ATA shadow
 *      registers.  Then parse according to the Error register value,
 *      and the spec-defined values examined by ata_dev_classify().
 *
 *      LOCKING:
 *      caller.
 *
 *      RETURNS:
 *      Device type - %ATA_DEV_ATA, %ATA_DEV_ATAPI or %ATA_DEV_NONE.
 */

static unsigned int
ata_dev_try_classify(struct ata_port *ap, unsigned int device, u8 *r_err)
{
        struct ata_taskfile tf;
        unsigned int class;
        u8 err;

        ap->ops->dev_select(ap, device);

        memset(&tf, 0, sizeof(tf));

        ap->ops->tf_read(ap, &tf);
        err = tf.feature;
        if (r_err)
                *r_err = err;

        /* see if device passed diags */
        if (err == 1)
                /* do nothing */ ;
        else if ((device == 0) && (err == 0x81))
                /* do nothing */ ;
        else
                return ATA_DEV_NONE;

        /* determine if device is ATA or ATAPI */
        class = ata_dev_classify(&tf);

        if (class == ATA_DEV_UNKNOWN)
                return ATA_DEV_NONE;
        if ((class == ATA_DEV_ATA) && (ata_chk_status(ap) == 0))
                return ATA_DEV_NONE;
        return class;
}

/**
 *      ata_id_string - Convert IDENTIFY DEVICE page into string
 *      @id: IDENTIFY DEVICE results we will examine
 *      @s: string into which data is output
 *      @ofs: offset into identify device page
 *      @len: length of string to return. must be an even number.
 *
 *      The strings in the IDENTIFY DEVICE page are broken up into
 *      16-bit chunks.  Run through the string, and output each
 *      8-bit chunk linearly, regardless of platform.
 *
 *      LOCKING:
 *      caller.
 */

void ata_id_string(const u16 *id, unsigned char *s,
                   unsigned int ofs, unsigned int len)
{
        unsigned int c;

        while (len > 0) {
                c = id[ofs] >> 8;
                *s = c;
                s++;

                c = id[ofs] & 0xff;
                *s = c;
                s++;

                ofs++;
                len -= 2;
        }
}

/**
 *      ata_id_c_string - Convert IDENTIFY DEVICE page into C string
 *      @id: IDENTIFY DEVICE results we will examine
 *      @s: string into which data is output
 *      @ofs: offset into identify device page
 *      @len: length of string to return. must be an odd number.
 *
 *      This function is identical to ata_id_string except that it
 *      trims trailing spaces and terminates the resulting string with
 *      null.  @len must be actual maximum length (even number) + 1.
 *
 *      LOCKING:
 *      caller.
 */
void ata_id_c_string(const u16 *id, unsigned char *s,
                     unsigned int ofs, unsigned int len)
{
        unsigned char *p;

        WARN_ON(!(len & 1));

        ata_id_string(id, s, ofs, len - 1);

        p = s + strnlen(s, len - 1);
        while (p > s && p[-1] == ' ')
                p--;
        *p = '\0';
}

static u64 ata_id_n_sectors(const u16 *id)
{
        if (ata_id_has_lba(id)) {
                if (ata_id_has_lba48(id))
                        return ata_id_u64(id, 100);
                else
                        return ata_id_u32(id, 60);
        } else {
                if (ata_id_current_chs_valid(id))
                        return ata_id_u32(id, 57);
                else
                        return id[1] * id[3] * id[6];
        }
}

/**
 *      ata_noop_dev_select - Select device 0/1 on ATA bus
 *      @ap: ATA channel to manipulate
 *      @device: ATA device (numbered from zero) to select
 *
 *      This function performs no actual function.
 *
 *      May be used as the dev_select() entry in ata_port_operations.
 *
 *      LOCKING:
 *      caller.
 */
void ata_noop_dev_select (struct ata_port *ap, unsigned int device)
{
}


/**
 *      ata_std_dev_select - Select device 0/1 on ATA bus
 *      @ap: ATA channel to manipulate
 *      @device: ATA device (numbered from zero) to select
 *
 *      Use the method defined in the ATA specification to
 *      make either device 0, or device 1, active on the
 *      ATA channel.  Works with both PIO and MMIO.
 *
 *      May be used as the dev_select() entry in ata_port_operations.
 *
 *      LOCKING:
 *      caller.
 */

void ata_std_dev_select (struct ata_port *ap, unsigned int device)
{
        u8 tmp;

        if (device == 0)
                tmp = ATA_DEVICE_OBS;
        else
                tmp = ATA_DEVICE_OBS | ATA_DEV1;

        if (ap->flags & ATA_FLAG_MMIO) {
                writeb(tmp, (void __iomem *) ap->ioaddr.device_addr);
        } else {
                outb(tmp, ap->ioaddr.device_addr);
        }
        ata_pause(ap);          /* needed; also flushes, for mmio */
}

/**
 *      ata_dev_select - Select device 0/1 on ATA bus
 *      @ap: ATA channel to manipulate
 *      @device: ATA device (numbered from zero) to select
 *      @wait: non-zero to wait for Status register BSY bit to clear
 *      @can_sleep: non-zero if context allows sleeping
 *
 *      Use the method defined in the ATA specification to
 *      make either device 0, or device 1, active on the
 *      ATA channel.
 *
 *      This is a high-level version of ata_std_dev_select(),
 *      which additionally provides the services of inserting
 *      the proper pauses and status polling, where needed.
 *
 *      LOCKING:
 *      caller.
 */

void ata_dev_select(struct ata_port *ap, unsigned int device,
                           unsigned int wait, unsigned int can_sleep)
{
        if (ata_msg_probe(ap))
                ata_port_printk(ap, KERN_INFO, "ata_dev_select: ENTER, ata%u: "
                                "device %u, wait %u\n", ap->id, device, wait);

        if (wait)
                ata_wait_idle(ap);

        ap->ops->dev_select(ap, device);

        if (wait) {
                if (can_sleep && ap->device[device].class == ATA_DEV_ATAPI)
                        msleep(150);
                ata_wait_idle(ap);
        }
}

/**
 *      ata_dump_id - IDENTIFY DEVICE info debugging output
 *      @id: IDENTIFY DEVICE page to dump
 *
 *      Dump selected 16-bit words from the given IDENTIFY DEVICE
 *      page.
 *
 *      LOCKING:
 *      caller.
 */

static inline void ata_dump_id(const u16 *id)
{
        DPRINTK("49==0x%04x  "
                "53==0x%04x  "
                "63==0x%04x  "
                "64==0x%04x  "
                "75==0x%04x  \n",
                id[49],
                id[53],
                id[63],
                id[64],
                id[75]);
        DPRINTK("80==0x%04x  "
                "81==0x%04x  "
                "82==0x%04x  "
                "83==0x%04x  "
                "84==0x%04x  \n",
                id[80],
                id[81],
                id[82],
                id[83],
                id[84]);
        DPRINTK("88==0x%04x  "
                "93==0x%04x\n",
                id[88],
                id[93]);
}

/**
 *      ata_id_xfermask - Compute xfermask from the given IDENTIFY data
 *      @id: IDENTIFY data to compute xfer mask from
 *
 *      Compute the xfermask for this device. This is not as trivial
 *      as it seems if we must consider early devices correctly.
 *
 *      FIXME: pre IDE drive timing (do we care ?).
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      Computed xfermask
 */
static unsigned int ata_id_xfermask(const u16 *id)
{
        unsigned int pio_mask, mwdma_mask, udma_mask;

        /* Usual case. Word 53 indicates word 64 is valid */
        if (id[ATA_ID_FIELD_VALID] & (1 << 1)) {
                pio_mask = id[ATA_ID_PIO_MODES] & 0x03;
                pio_mask <<= 3;
                pio_mask |= 0x7;
        } else {
                /* If word 64 isn't valid then Word 51 high byte holds
                 * the PIO timing number for the maximum. Turn it into
                 * a mask.
                 */
                pio_mask = (2 << (id[ATA_ID_OLD_PIO_MODES] & 0xFF)) - 1 ;

                /* But wait.. there's more. Design your standards by
                 * committee and you too can get a free iordy field to
                 * process. However its the speeds not the modes that
                 * are supported... Note drivers using the timing API
                 * will get this right anyway
                 */
        }

        mwdma_mask = id[ATA_ID_MWDMA_MODES] & 0x07;

        udma_mask = 0;
        if (id[ATA_ID_FIELD_VALID] & (1 << 2))
                udma_mask = id[ATA_ID_UDMA_MODES] & 0xff;

        return ata_pack_xfermask(pio_mask, mwdma_mask, udma_mask);
}

/**
 *      ata_port_queue_task - Queue port_task
 *      @ap: The ata_port to queue port_task for
 *      @fn: workqueue function to be scheduled
 *      @data: data value to pass to workqueue function
 *      @delay: delay time for workqueue function
 *
 *      Schedule @fn(@data) for execution after @delay jiffies using
 *      port_task.  There is one port_task per port and it's the
 *      user(low level driver)'s responsibility to make sure that only
 *      one task is active at any given time.
 *
 *      libata core layer takes care of synchronization between
 *      port_task and EH.  ata_port_queue_task() may be ignored for EH
 *      synchronization.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
void ata_port_queue_task(struct ata_port *ap, void (*fn)(void *), void *data,
                         unsigned long delay)
{
        int rc;

        if (ap->flags & ATA_FLAG_FLUSH_PORT_TASK)
                return;

        PREPARE_WORK(&ap->port_task, fn, data);

        if (!delay)
                rc = queue_work(ata_wq, &ap->port_task);
        else
                rc = queue_delayed_work(ata_wq, &ap->port_task, delay);

        /* rc == 0 means that another user is using port task */
        WARN_ON(rc == 0);
}

/**
 *      ata_port_flush_task - Flush port_task
 *      @ap: The ata_port to flush port_task for
 *
 *      After this function completes, port_task is guranteed not to
 *      be running or scheduled.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 */
void ata_port_flush_task(struct ata_port *ap)
{
        unsigned long flags;

        DPRINTK("ENTER\n");

        spin_lock_irqsave(ap->lock, flags);
        ap->flags |= ATA_FLAG_FLUSH_PORT_TASK;
        spin_unlock_irqrestore(ap->lock, flags);

        DPRINTK("flush #1\n");
        flush_workqueue(ata_wq);

        /*
         * At this point, if a task is running, it's guaranteed to see
         * the FLUSH flag; thus, it will never queue pio tasks again.
         * Cancel and flush.
         */
        if (!cancel_delayed_work(&ap->port_task)) {
                if (ata_msg_ctl(ap))
                        ata_port_printk(ap, KERN_DEBUG, "%s: flush #2\n",
                                        __FUNCTION__);
                flush_workqueue(ata_wq);
        }

        spin_lock_irqsave(ap->lock, flags);
        ap->flags &= ~ATA_FLAG_FLUSH_PORT_TASK;
        spin_unlock_irqrestore(ap->lock, flags);

        if (ata_msg_ctl(ap))
                ata_port_printk(ap, KERN_DEBUG, "%s: EXIT\n", __FUNCTION__);
}

void ata_qc_complete_internal(struct ata_queued_cmd *qc)
{
        struct completion *waiting = qc->private_data;

        complete(waiting);
}

/**
 *      ata_exec_internal - execute libata internal command
 *      @dev: Device to which the command is sent
 *      @tf: Taskfile registers for the command and the result
 *      @cdb: CDB for packet command
 *      @dma_dir: Data tranfer direction of the command
 *      @buf: Data buffer of the command
 *      @buflen: Length of data buffer
 *
 *      Executes libata internal command with timeout.  @tf contains
 *      command on entry and result on return.  Timeout and error
 *      conditions are reported via return value.  No recovery action
 *      is taken after a command times out.  It's caller's duty to
 *      clean up after timeout.
 *
 *      LOCKING:
 *      None.  Should be called with kernel context, might sleep.
 *
 *      RETURNS:
 *      Zero on success, AC_ERR_* mask on failure
 */
unsigned ata_exec_internal(struct ata_device *dev,
                           struct ata_taskfile *tf, const u8 *cdb,
                           int dma_dir, void *buf, unsigned int buflen)
{
        struct ata_port *ap = dev->ap;
        u8 command = tf->command;
        struct ata_queued_cmd *qc;
        unsigned int tag, preempted_tag;
        u32 preempted_sactive, preempted_qc_active;
        DECLARE_COMPLETION_ONSTACK(wait);
        unsigned long flags;
        unsigned int err_mask;
        int rc;

        spin_lock_irqsave(ap->lock, flags);

        /* no internal command while frozen */
        if (ap->flags & ATA_FLAG_FROZEN) {
                spin_unlock_irqrestore(ap->lock, flags);
                return AC_ERR_SYSTEM;
        }

        /* initialize internal qc */

        /* XXX: Tag 0 is used for drivers with legacy EH as some
         * drivers choke if any other tag is given.  This breaks
         * ata_tag_internal() test for those drivers.  Don't use new
         * EH stuff without converting to it.
         */
        if (ap->ops->error_handler)
                tag = ATA_TAG_INTERNAL;
        else
                tag = 0;

        if (test_and_set_bit(tag, &ap->qc_allocated))
                BUG();
        qc = __ata_qc_from_tag(ap, tag);

        qc->tag = tag;
        qc->scsicmd = NULL;
        qc->ap = ap;
        qc->dev = dev;
        ata_qc_reinit(qc);

        preempted_tag = ap->active_tag;
        preempted_sactive = ap->sactive;
        preempted_qc_active = ap->qc_active;
        ap->active_tag = ATA_TAG_POISON;
        ap->sactive = 0;
        ap->qc_active = 0;

        /* prepare & issue qc */
        qc->tf = *tf;
        if (cdb)
                memcpy(qc->cdb, cdb, ATAPI_CDB_LEN);
        qc->flags |= ATA_QCFLAG_RESULT_TF;
        qc->dma_dir = dma_dir;
        if (dma_dir != DMA_NONE) {
                ata_sg_init_one(qc, buf, buflen);
                qc->nsect = buflen / ATA_SECT_SIZE;
        }

        qc->private_data = &wait;
        qc->complete_fn = ata_qc_complete_internal;

        ata_qc_issue(qc);

        spin_unlock_irqrestore(ap->lock, flags);

        rc = wait_for_completion_timeout(&wait, ata_probe_timeout);

        ata_port_flush_task(ap);

        if (!rc) {
                spin_lock_irqsave(ap->lock, flags);

                /* We're racing with irq here.  If we lose, the
                 * following test prevents us from completing the qc
                 * twice.  If we win, the port is frozen and will be
                 * cleaned up by ->post_internal_cmd().
                 */
                if (qc->flags & ATA_QCFLAG_ACTIVE) {
                        qc->err_mask |= AC_ERR_TIMEOUT;

                        if (ap->ops->error_handler)
                                ata_port_freeze(ap);
                        else
                                ata_qc_complete(qc);

                        if (ata_msg_warn(ap))
                                ata_dev_printk(dev, KERN_WARNING,
                                        "qc timeout (cmd 0x%x)\n", command);
                }

                spin_unlock_irqrestore(ap->lock, flags);
        }

        /* do post_internal_cmd */
        if (ap->ops->post_internal_cmd)
                ap->ops->post_internal_cmd(qc);

        if (qc->flags & ATA_QCFLAG_FAILED && !qc->err_mask) {
                if (ata_msg_warn(ap))
                        ata_dev_printk(dev, KERN_WARNING,
                                "zero err_mask for failed "
                                "internal command, assuming AC_ERR_OTHER\n");
                qc->err_mask |= AC_ERR_OTHER;
        }

        /* finish up */
        spin_lock_irqsave(ap->lock, flags);

        *tf = qc->result_tf;
        err_mask = qc->err_mask;

        ata_qc_free(qc);
        ap->active_tag = preempted_tag;
        ap->sactive = preempted_sactive;
        ap->qc_active = preempted_qc_active;

        /* XXX - Some LLDDs (sata_mv) disable port on command failure.
         * Until those drivers are fixed, we detect the condition
         * here, fail the command with AC_ERR_SYSTEM and reenable the
         * port.
         *
         * Note that this doesn't change any behavior as internal
         * command failure results in disabling the device in the
         * higher layer for LLDDs without new reset/EH callbacks.
         *
         * Kill the following code as soon as those drivers are fixed.
         */
        if (ap->flags & ATA_FLAG_DISABLED) {
                err_mask |= AC_ERR_SYSTEM;
                ata_port_probe(ap);
        }

        spin_unlock_irqrestore(ap->lock, flags);

        return err_mask;
}

/**
 *      ata_do_simple_cmd - execute simple internal command
 *      @dev: Device to which the command is sent
 *      @cmd: Opcode to execute
 *
 *      Execute a 'simple' command, that only consists of the opcode
 *      'cmd' itself, without filling any other registers
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 *
 *      RETURNS:
 *      Zero on success, AC_ERR_* mask on failure
 */
unsigned int ata_do_simple_cmd(struct ata_device *dev, u8 cmd)
{
        struct ata_taskfile tf;

        ata_tf_init(dev, &tf);

        tf.command = cmd;
        tf.flags |= ATA_TFLAG_DEVICE;
        tf.protocol = ATA_PROT_NODATA;

        return ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0);
}

/**
 *      ata_pio_need_iordy      -       check if iordy needed
 *      @adev: ATA device
 *
 *      Check if the current speed of the device requires IORDY. Used
 *      by various controllers for chip configuration.
 */

unsigned int ata_pio_need_iordy(const struct ata_device *adev)
{
        int pio;
        int speed = adev->pio_mode - XFER_PIO_0;

        if (speed < 2)
                return 0;
        if (speed > 2)
                return 1;

        /* If we have no drive specific rule, then PIO 2 is non IORDY */

        if (adev->id[ATA_ID_FIELD_VALID] & 2) { /* EIDE */
                pio = adev->id[ATA_ID_EIDE_PIO];
                /* Is the speed faster than the drive allows non IORDY ? */
                if (pio) {
                        /* This is cycle times not frequency - watch the logic! */
                        if (pio > 240)  /* PIO2 is 240nS per cycle */
                                return 1;
                        return 0;
                }
        }
        return 0;
}

/**
 *      ata_dev_read_id - Read ID data from the specified device
 *      @dev: target device
 *      @p_class: pointer to class of the target device (may be changed)
 *      @post_reset: is this read ID post-reset?
 *      @id: buffer to read IDENTIFY data into
 *
 *      Read ID data from the specified device.  ATA_CMD_ID_ATA is
 *      performed on ATA devices and ATA_CMD_ID_ATAPI on ATAPI
 *      devices.  This function also issues ATA_CMD_INIT_DEV_PARAMS
 *      for pre-ATA4 drives.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
                    int post_reset, u16 *id)
{
        struct ata_port *ap = dev->ap;
        unsigned int class = *p_class;
        struct ata_taskfile tf;
        unsigned int err_mask = 0;
        const char *reason;
        int rc;

        if (ata_msg_ctl(ap))
                ata_dev_printk(dev, KERN_DEBUG, "%s: ENTER, host %u, dev %u\n",
                               __FUNCTION__, ap->id, dev->devno);

        ata_dev_select(ap, dev->devno, 1, 1); /* select device 0/1 */

 retry:
        ata_tf_init(dev, &tf);

        switch (class) {
        case ATA_DEV_ATA:
                tf.command = ATA_CMD_ID_ATA;
                break;
        case ATA_DEV_ATAPI:
                tf.command = ATA_CMD_ID_ATAPI;
                break;
        default:
                rc = -ENODEV;
                reason = "unsupported class";
                goto err_out;
        }

        tf.protocol = ATA_PROT_PIO;

        err_mask = ata_exec_internal(dev, &tf, NULL, DMA_FROM_DEVICE,
                                     id, sizeof(id[0]) * ATA_ID_WORDS);
        if (err_mask) {
                rc = -EIO;
                reason = "I/O error";
                goto err_out;
        }

        swap_buf_le16(id, ATA_ID_WORDS);

        /* sanity check */
        if ((class == ATA_DEV_ATA) != (ata_id_is_ata(id) | ata_id_is_cfa(id))) {
                rc = -EINVAL;
                reason = "device reports illegal type";
                goto err_out;
        }

        if (post_reset && class == ATA_DEV_ATA) {
                /*
                 * The exact sequence expected by certain pre-ATA4 drives is:
                 * SRST RESET
                 * IDENTIFY
                 * INITIALIZE DEVICE PARAMETERS
                 * anything else..
                 * Some drives were very specific about that exact sequence.
                 */
                if (ata_id_major_version(id) < 4 || !ata_id_has_lba(id)) {
                        err_mask = ata_dev_init_params(dev, id[3], id[6]);
                        if (err_mask) {
                                rc = -EIO;
                                reason = "INIT_DEV_PARAMS failed";
                                goto err_out;
                        }

                        /* current CHS translation info (id[53-58]) might be
                         * changed. reread the identify device info.
                         */
                        post_reset = 0;
                        goto retry;
                }
        }

        *p_class = class;

        return 0;

 err_out:
        if (ata_msg_warn(ap))
                ata_dev_printk(dev, KERN_WARNING, "failed to IDENTIFY "
                               "(%s, err_mask=0x%x)\n", reason, err_mask);
        return rc;
}

static inline u8 ata_dev_knobble(struct ata_device *dev)
{
        return ((dev->ap->cbl == ATA_CBL_SATA) && (!ata_id_is_sata(dev->id)));
}

static void ata_dev_config_ncq(struct ata_device *dev,
                               char *desc, size_t desc_sz)
{
        struct ata_port *ap = dev->ap;
        int hdepth = 0, ddepth = ata_id_queue_depth(dev->id);

        if (!ata_id_has_ncq(dev->id)) {
                desc[0] = '\0';
                return;
        }

        if (ap->flags & ATA_FLAG_NCQ) {
                hdepth = min(ap->host->can_queue, ATA_MAX_QUEUE - 1);
                dev->flags |= ATA_DFLAG_NCQ;
        }

        if (hdepth >= ddepth)
                snprintf(desc, desc_sz, "NCQ (depth %d)", ddepth);
        else
                snprintf(desc, desc_sz, "NCQ (depth %d/%d)", hdepth, ddepth);
}

static void ata_set_port_max_cmd_len(struct ata_port *ap)
{
        int i;

        if (ap->host) {
                ap->host->max_cmd_len = 0;
                for (i = 0; i < ATA_MAX_DEVICES; i++)
                        ap->host->max_cmd_len = max_t(unsigned int,
                                                      ap->host->max_cmd_len,
                                                      ap->device[i].cdb_len);
        }
}

/**
 *      ata_dev_configure - Configure the specified ATA/ATAPI device
 *      @dev: Target device to configure
 *      @print_info: Enable device info printout
 *
 *      Configure @dev according to @dev->id.  Generic and low-level
 *      driver specific fixups are also applied.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise
 */
int ata_dev_configure(struct ata_device *dev, int print_info)
{
        struct ata_port *ap = dev->ap;
        const u16 *id = dev->id;
        unsigned int xfer_mask;
        int rc;

        if (!ata_dev_enabled(dev) && ata_msg_info(ap)) {
                ata_dev_printk(dev, KERN_INFO,
                               "%s: ENTER/EXIT (host %u, dev %u) -- nodev\n",
                               __FUNCTION__, ap->id, dev->devno);
                return 0;
        }

        if (ata_msg_probe(ap))
                ata_dev_printk(dev, KERN_DEBUG, "%s: ENTER, host %u, dev %u\n",
                               __FUNCTION__, ap->id, dev->devno);

        /* print device capabilities */
        if (ata_msg_probe(ap))
                ata_dev_printk(dev, KERN_DEBUG,
                               "%s: cfg 49:%04x 82:%04x 83:%04x 84:%04x "
                               "85:%04x 86:%04x 87:%04x 88:%04x\n",
                               __FUNCTION__,
                               id[49], id[82], id[83], id[84],
                               id[85], id[86], id[87], id[88]);

        /* initialize to-be-configured parameters */
        dev->flags &= ~ATA_DFLAG_CFG_MASK;
        dev->max_sectors = 0;
        dev->cdb_len = 0;
        dev->n_sectors = 0;
        dev->cylinders = 0;
        dev->heads = 0;
        dev->sectors = 0;

        /*
         * common ATA, ATAPI feature tests
         */

        /* find max transfer mode; for printk only */
        xfer_mask = ata_id_xfermask(id);

        if (ata_msg_probe(ap))
                ata_dump_id(id);

        /* ATA-specific feature tests */
        if (dev->class == ATA_DEV_ATA) {
                dev->n_sectors = ata_id_n_sectors(id);

                if (ata_id_has_lba(id)) {
                        const char *lba_desc;
                        char ncq_desc[20];

                        lba_desc = "LBA";
                        dev->flags |= ATA_DFLAG_LBA;
                        if (ata_id_has_lba48(id)) {
                                dev->flags |= ATA_DFLAG_LBA48;
                                lba_desc = "LBA48";
                        }

                        /* config NCQ */
                        ata_dev_config_ncq(dev, ncq_desc, sizeof(ncq_desc));

                        /* print device info to dmesg */
                        if (ata_msg_info(ap))
                                ata_dev_printk(dev, KERN_INFO, "ATA-%d, "
                                        "max %s, %Lu sectors: %s %s\n",
                                        ata_id_major_version(id),
                                        ata_mode_string(xfer_mask),
                                        (unsigned long long)dev->n_sectors,
                                        lba_desc, ncq_desc);
                } else {
                        /* CHS */

                        /* Default translation */
                        dev->cylinders  = id[1];
                        dev->heads      = id[3];
                        dev->sectors    = id[6];

                        if (ata_id_current_chs_valid(id)) {
                                /* Current CHS translation is valid. */
                                dev->cylinders = id[54];
                                dev->heads     = id[55];
                                dev->sectors   = id[56];
                        }

                        /* print device info to dmesg */
                        if (ata_msg_info(ap))
                                ata_dev_printk(dev, KERN_INFO, "ATA-%d, "
                                        "max %s, %Lu sectors: CHS %u/%u/%u\n",
                                        ata_id_major_version(id),
                                        ata_mode_string(xfer_mask),
                                        (unsigned long long)dev->n_sectors,
                                        dev->cylinders, dev->heads,
                                        dev->sectors);
                }

                if (dev->id[59] & 0x100) {
                        dev->multi_count = dev->id[59] & 0xff;
                        if (ata_msg_info(ap))
                                ata_dev_printk(dev, KERN_INFO,
                                        "ata%u: dev %u multi count %u\n",
                                        ap->id, dev->devno, dev->multi_count);
                }

                dev->cdb_len = 16;
        }

        /* ATAPI-specific feature tests */
        else if (dev->class == ATA_DEV_ATAPI) {
                char *cdb_intr_string = "";

                rc = atapi_cdb_len(id);
                if ((rc < 12) || (rc > ATAPI_CDB_LEN)) {
                        if (ata_msg_warn(ap))
                                ata_dev_printk(dev, KERN_WARNING,
                                               "unsupported CDB len\n");
                        rc = -EINVAL;
                        goto err_out_nosup;
                }
                dev->cdb_len = (unsigned int) rc;

                if (ata_id_cdb_intr(dev->id)) {
                        dev->flags |= ATA_DFLAG_CDB_INTR;
                        cdb_intr_string = ", CDB intr";
                }

                /* print device info to dmesg */
                if (ata_msg_info(ap))
                        ata_dev_printk(dev, KERN_INFO, "ATAPI, max %s%s\n",
                                       ata_mode_string(xfer_mask),
                                       cdb_intr_string);
        }

        ata_set_port_max_cmd_len(ap);

        /* limit bridge transfers to udma5, 200 sectors */
        if (ata_dev_knobble(dev)) {
                if (ata_msg_info(ap))
                        ata_dev_printk(dev, KERN_INFO,
                                       "applying bridge limits\n");
                dev->udma_mask &= ATA_UDMA5;
                dev->max_sectors = ATA_MAX_SECTORS;
        }

        if (ap->ops->dev_config)
                ap->ops->dev_config(ap, dev);

        if (ata_msg_probe(ap))
                ata_dev_printk(dev, KERN_DEBUG, "%s: EXIT, drv_stat = 0x%x\n",
                        __FUNCTION__, ata_chk_status(ap));
        return 0;

err_out_nosup:
        if (ata_msg_probe(ap))
                ata_dev_printk(dev, KERN_DEBUG,
                               "%s: EXIT, err\n", __FUNCTION__);
        return rc;
}

/**
 *      ata_bus_probe - Reset and probe ATA bus
 *      @ap: Bus to probe
 *
 *      Master ATA bus probing function.  Initiates a hardware-dependent
 *      bus reset, then attempts to identify any devices found on
 *      the bus.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 *      RETURNS:
 *      Zero on success, negative errno otherwise.
 */

static int ata_bus_probe(struct ata_port *ap)
{
        unsigned int classes[ATA_MAX_DEVICES];
        int tries[ATA_MAX_DEVICES];
        int i, rc, down_xfermask;
        struct ata_device *dev;

        ata_port_probe(ap);

        for (i = 0; i < ATA_MAX_DEVICES; i++)
                tries[i] = ATA_PROBE_MAX_TRIES;

 retry:
        down_xfermask = 0;

        /* reset and determine device classes */
        ap->ops->phy_reset(ap);

        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                dev = &ap->device[i];

                if (!(ap->flags & ATA_FLAG_DISABLED) &&
                    dev->class != ATA_DEV_UNKNOWN)
                        classes[dev->devno] = dev->class;
                else
                        classes[dev->devno] = ATA_DEV_NONE;

                dev->class = ATA_DEV_UNKNOWN;
        }

        ata_port_probe(ap);

        /* after the reset the device state is PIO 0 and the controller
           state is undefined. Record the mode */

        for (i = 0; i < ATA_MAX_DEVICES; i++)
                ap->device[i].pio_mode = XFER_PIO_0;

        /* read IDENTIFY page and configure devices */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                dev = &ap->device[i];

                if (tries[i])
                        dev->class = classes[i];

                if (!ata_dev_enabled(dev))
                        continue;

                rc = ata_dev_read_id(dev, &dev->class, 1, dev->id);
                if (rc)
                        goto fail;

                rc = ata_dev_configure(dev, 1);
                if (rc)
                        goto fail;
        }

        /* configure transfer mode */
        rc = ata_set_mode(ap, &dev);
        if (rc) {
                down_xfermask = 1;
                goto fail;
        }

        for (i = 0; i < ATA_MAX_DEVICES; i++)
                if (ata_dev_enabled(&ap->device[i]))
                        return 0;

        /* no device present, disable port */
        ata_port_disable(ap);
        ap->ops->port_disable(ap);
        return -ENODEV;

 fail:
        switch (rc) {
        case -EINVAL:
        case -ENODEV:
                tries[dev->devno] = 0;
                break;
        case -EIO:
                sata_down_spd_limit(ap);
                /* fall through */
        default:
                tries[dev->devno]--;
                if (down_xfermask &&
                    ata_down_xfermask_limit(dev, tries[dev->devno] == 1))
                        tries[dev->devno] = 0;
        }

        if (!tries[dev->devno]) {
                ata_down_xfermask_limit(dev, 1);
                ata_dev_disable(dev);
        }

        goto retry;
}

/**
 *      ata_port_probe - Mark port as enabled
 *      @ap: Port for which we indicate enablement
 *
 *      Modify @ap data structure such that the system
 *      thinks that the entire port is enabled.
 *
 *      LOCKING: host_set lock, or some other form of
 *      serialization.
 */

void ata_port_probe(struct ata_port *ap)
{
        ap->flags &= ~ATA_FLAG_DISABLED;
}

/**
 *      sata_print_link_status - Print SATA link status
 *      @ap: SATA port to printk link status about
 *
 *      This function prints link speed and status of a SATA link.
 *
 *      LOCKING:
 *      None.
 */
static void sata_print_link_status(struct ata_port *ap)
{
        u32 sstatus, scontrol, tmp;

        if (sata_scr_read(ap, SCR_STATUS, &sstatus))
                return;
        sata_scr_read(ap, SCR_CONTROL, &scontrol);

        if (ata_port_online(ap)) {
                tmp = (sstatus >> 4) & 0xf;
                ata_port_printk(ap, KERN_INFO,
                                "SATA link up %s (SStatus %X SControl %X)\n",
                                sata_spd_string(tmp), sstatus, scontrol);
        } else {
                ata_port_printk(ap, KERN_INFO,
                                "SATA link down (SStatus %X SControl %X)\n",
                                sstatus, scontrol);
        }
}

/**
 *      __sata_phy_reset - Wake/reset a low-level SATA PHY
 *      @ap: SATA port associated with target SATA PHY.
 *
 *      This function issues commands to standard SATA Sxxx
 *      PHY registers, to wake up the phy (and device), and
 *      clear any reset condition.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 */
void __sata_phy_reset(struct ata_port *ap)
{
        u32 sstatus;
        unsigned long timeout = jiffies + (HZ * 5);

        if (ap->flags & ATA_FLAG_SATA_RESET) {
                /* issue phy wake/reset */
                sata_scr_write_flush(ap, SCR_CONTROL, 0x301);
                /* Couldn't find anything in SATA I/II specs, but
                 * AHCI-1.1 10.4.2 says at least 1 ms. */
                mdelay(1);
        }
        /* phy wake/clear reset */
        sata_scr_write_flush(ap, SCR_CONTROL, 0x300);

        /* wait for phy to become ready, if necessary */
        do {
                msleep(200);
                sata_scr_read(ap, SCR_STATUS, &sstatus);
                if ((sstatus & 0xf) != 1)
                        break;
        } while (time_before(jiffies, timeout));

        /* print link status */
        sata_print_link_status(ap);

        /* TODO: phy layer with polling, timeouts, etc. */
        if (!ata_port_offline(ap))
                ata_port_probe(ap);
        else
                ata_port_disable(ap);

        if (ap->flags & ATA_FLAG_DISABLED)
                return;

        if (ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT)) {
                ata_port_disable(ap);
                return;
        }

        ap->cbl = ATA_CBL_SATA;
}

/**
 *      sata_phy_reset - Reset SATA bus.
 *      @ap: SATA port associated with target SATA PHY.
 *
 *      This function resets the SATA bus, and then probes
 *      the bus for devices.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 */
void sata_phy_reset(struct ata_port *ap)
{
        __sata_phy_reset(ap);
        if (ap->flags & ATA_FLAG_DISABLED)
                return;
        ata_bus_reset(ap);
}

/**
 *      ata_dev_pair            -       return other device on cable
 *      @adev: device
 *
 *      Obtain the other device on the same cable, or if none is
 *      present NULL is returned
 */

struct ata_device *ata_dev_pair(struct ata_device *adev)
{
        struct ata_port *ap = adev->ap;
        struct ata_device *pair = &ap->device[1 - adev->devno];
        if (!ata_dev_enabled(pair))
                return NULL;
        return pair;
}

/**
 *      ata_port_disable - Disable port.
 *      @ap: Port to be disabled.
 *
 *      Modify @ap data structure such that the system
 *      thinks that the entire port is disabled, and should
 *      never attempt to probe or communicate with devices
 *      on this port.
 *
 *      LOCKING: host_set lock, or some other form of
 *      serialization.
 */

void ata_port_disable(struct ata_port *ap)
{
        ap->device[0].class = ATA_DEV_NONE;
        ap->device[1].class = ATA_DEV_NONE;
        ap->flags |= ATA_FLAG_DISABLED;
}

/**
 *      sata_down_spd_limit - adjust SATA spd limit downward
 *      @ap: Port to adjust SATA spd limit for
 *
 *      Adjust SATA spd limit of @ap downward.  Note that this
 *      function only adjusts the limit.  The change must be applied
 *      using sata_set_spd().
 *
 *      LOCKING:
 *      Inherited from caller.
 *
 *      RETURNS:
 *      0 on success, negative errno on failure
 */
int sata_down_spd_limit(struct ata_port *ap)
{
        u32 sstatus, spd, mask;
        int rc, highbit;

        rc = sata_scr_read(ap, SCR_STATUS, &sstatus);
        if (rc)
                return rc;

        mask = ap->sata_spd_limit;
        if (mask <= 1)
                return -EINVAL;
        highbit = fls(mask) - 1;
        mask &= ~(1 << highbit);

        spd = (sstatus >> 4) & 0xf;
        if (spd <= 1)
                return -EINVAL;
        spd--;
        mask &= (1 << spd) - 1;
        if (!mask)
                return -EINVAL;

        ap->sata_spd_limit = mask;

        ata_port_printk(ap, KERN_WARNING, "limiting SATA link speed to %s\n",
                        sata_spd_string(fls(mask)));

        return 0;
}

static int __sata_set_spd_needed(struct ata_port *ap, u32 *scontrol)
{
        u32 spd, limit;

        if (ap->sata_spd_limit == UINT_MAX)
                limit = 0;
        else
                limit = fls(ap->sata_spd_limit);

        spd = (*scontrol >> 4) & 0xf;
        *scontrol = (*scontrol & ~0xf0) | ((limit & 0xf) << 4);

        return spd != limit;
}

/**
 *      sata_set_spd_needed - is SATA spd configuration needed
 *      @ap: Port in question
 *
 *      Test whether the spd limit in SControl matches
 *      @ap->sata_spd_limit.  This function is used to determine
 *      whether hardreset is necessary to apply SATA spd
 *      configuration.
 *
 *      LOCKING:
 *      Inherited from caller.
 *
 *      RETURNS:
 *      1 if SATA spd configuration is needed, 0 otherwise.
 */
int sata_set_spd_needed(struct ata_port *ap)
{
        u32 scontrol;

        if (sata_scr_read(ap, SCR_CONTROL, &scontrol))
                return 0;

        return __sata_set_spd_needed(ap, &scontrol);
}

/**
 *      sata_set_spd - set SATA spd according to spd limit
 *      @ap: Port to set SATA spd for
 *
 *      Set SATA spd of @ap according to sata_spd_limit.
 *
 *      LOCKING:
 *      Inherited from caller.
 *
 *      RETURNS:
 *      0 if spd doesn't need to be changed, 1 if spd has been
 *      changed.  Negative errno if SCR registers are inaccessible.
 */
int sata_set_spd(struct ata_port *ap)
{
        u32 scontrol;
        int rc;

        if ((rc = sata_scr_read(ap, SCR_CONTROL, &scontrol)))
                return rc;

        if (!__sata_set_spd_needed(ap, &scontrol))
                return 0;

        if ((rc = sata_scr_write(ap, SCR_CONTROL, scontrol)))
                return rc;

        return 1;
}

/*
 * This mode timing computation functionality is ported over from
 * drivers/ide/ide-timing.h and was originally written by Vojtech Pavlik
 */
/*
 * PIO 0-5, MWDMA 0-2 and UDMA 0-6 timings (in nanoseconds).
 * These were taken from ATA/ATAPI-6 standard, rev 0a, except
 * for PIO 5, which is a nonstandard extension and UDMA6, which
 * is currently supported only by Maxtor drives.
 */

static const struct ata_timing ata_timing[] = {

        { XFER_UDMA_6,     0,   0,   0,   0,   0,   0,   0,  15 },
        { XFER_UDMA_5,     0,   0,   0,   0,   0,   0,   0,  20 },
        { XFER_UDMA_4,     0,   0,   0,   0,   0,   0,   0,  30 },
        { XFER_UDMA_3,     0,   0,   0,   0,   0,   0,   0,  45 },

        { XFER_UDMA_2,     0,   0,   0,   0,   0,   0,   0,  60 },
        { XFER_UDMA_1,     0,   0,   0,   0,   0,   0,   0,  80 },
        { XFER_UDMA_0,     0,   0,   0,   0,   0,   0,   0, 120 },

/*      { XFER_UDMA_SLOW,  0,   0,   0,   0,   0,   0,   0, 150 }, */

        { XFER_MW_DMA_2,  25,   0,   0,   0,  70,  25, 120,   0 },
        { XFER_MW_DMA_1,  45,   0,   0,   0,  80,  50, 150,   0 },
        { XFER_MW_DMA_0,  60,   0,   0,   0, 215, 215, 480,   0 },

        { XFER_SW_DMA_2,  60,   0,   0,   0, 120, 120, 240,   0 },
        { XFER_SW_DMA_1,  90,   0,   0,   0, 240, 240, 480,   0 },
        { XFER_SW_DMA_0, 120,   0,   0,   0, 480, 480, 960,   0 },

/*      { XFER_PIO_5,     20,  50,  30, 100,  50,  30, 100,   0 }, */
        { XFER_PIO_4,     25,  70,  25, 120,  70,  25, 120,   0 },
        { XFER_PIO_3,     30,  80,  70, 180,  80,  70, 180,   0 },

        { XFER_PIO_2,     30, 290,  40, 330, 100,  90, 240,   0 },
        { XFER_PIO_1,     50, 290,  93, 383, 125, 100, 383,   0 },
        { XFER_PIO_0,     70, 290, 240, 600, 165, 150, 600,   0 },

/*      { XFER_PIO_SLOW, 120, 290, 240, 960, 290, 240, 960,   0 }, */

        { 0xFF }
};

#define ENOUGH(v,unit)          (((v)-1)/(unit)+1)
#define EZ(v,unit)              ((v)?ENOUGH(v,unit):0)

static void ata_timing_quantize(const struct ata_timing *t, struct ata_timing *q, int T, int UT)
{
        q->setup   = EZ(t->setup   * 1000,  T);
        q->act8b   = EZ(t->act8b   * 1000,  T);
        q->rec8b   = EZ(t->rec8b   * 1000,  T);
        q->cyc8b   = EZ(t->cyc8b   * 1000,  T);
        q->active  = EZ(t->active  * 1000,  T);
        q->recover = EZ(t->recover * 1000,  T);
        q->cycle   = EZ(t->cycle   * 1000,  T);
        q->udma    = EZ(t->udma    * 1000, UT);
}

void ata_timing_merge(const struct ata_timing *a, const struct ata_timing *b,
                      struct ata_timing *m, unsigned int what)
{
        if (what & ATA_TIMING_SETUP  ) m->setup   = max(a->setup,   b->setup);
        if (what & ATA_TIMING_ACT8B  ) m->act8b   = max(a->act8b,   b->act8b);
        if (what & ATA_TIMING_REC8B  ) m->rec8b   = max(a->rec8b,   b->rec8b);
        if (what & ATA_TIMING_CYC8B  ) m->cyc8b   = max(a->cyc8b,   b->cyc8b);
        if (what & ATA_TIMING_ACTIVE ) m->active  = max(a->active,  b->active);
        if (what & ATA_TIMING_RECOVER) m->recover = max(a->recover, b->recover);
        if (what & ATA_TIMING_CYCLE  ) m->cycle   = max(a->cycle,   b->cycle);
        if (what & ATA_TIMING_UDMA   ) m->udma    = max(a->udma,    b->udma);
}

static const struct ata_timing* ata_timing_find_mode(unsigned short speed)
{
        const struct ata_timing *t;

        for (t = ata_timing; t->mode != speed; t++)
                if (t->mode == 0xFF)
                        return NULL;
        return t;
}

int ata_timing_compute(struct ata_device *adev, unsigned short speed,
                       struct ata_timing *t, int T, int UT)
{
        const struct ata_timing *s;
        struct ata_timing p;

        /*
         * Find the mode.
         */

        if (!(s = ata_timing_find_mode(speed)))
                return -EINVAL;

        memcpy(t, s, sizeof(*s));

        /*
         * If the drive is an EIDE drive, it can tell us it needs extended
         * PIO/MW_DMA cycle timing.
         */

        if (adev->id[ATA_ID_FIELD_VALID] & 2) { /* EIDE drive */
                memset(&p, 0, sizeof(p));
                if(speed >= XFER_PIO_0 && speed <= XFER_SW_DMA_0) {
                        if (speed <= XFER_PIO_2) p.cycle = p.cyc8b = adev->id[ATA_ID_EIDE_PIO];
                                            else p.cycle = p.cyc8b = adev->id[ATA_ID_EIDE_PIO_IORDY];
                } else if(speed >= XFER_MW_DMA_0 && speed <= XFER_MW_DMA_2) {
                        p.cycle = adev->id[ATA_ID_EIDE_DMA_MIN];
                }
                ata_timing_merge(&p, t, t, ATA_TIMING_CYCLE | ATA_TIMING_CYC8B);
        }

        /*
         * Convert the timing to bus clock counts.
         */

        ata_timing_quantize(t, t, T, UT);

        /*
         * Even in DMA/UDMA modes we still use PIO access for IDENTIFY,
         * S.M.A.R.T * and some other commands. We have to ensure that the
         * DMA cycle timing is slower/equal than the fastest PIO timing.
         */

        if (speed > XFER_PIO_4) {
                ata_timing_compute(adev, adev->pio_mode, &p, T, UT);
                ata_timing_merge(&p, t, t, ATA_TIMING_ALL);
        }

        /*
         * Lengthen active & recovery time so that cycle time is correct.
         */

        if (t->act8b + t->rec8b < t->cyc8b) {
                t->act8b += (t->cyc8b - (t->act8b + t->rec8b)) / 2;
                t->rec8b = t->cyc8b - t->act8b;
        }

        if (t->active + t->recover < t->cycle) {
                t->active += (t->cycle - (t->active + t->recover)) / 2;
                t->recover = t->cycle - t->active;
        }

        return 0;
}

/**
 *      ata_down_xfermask_limit - adjust dev xfer masks downward
 *      @dev: Device to adjust xfer masks
 *      @force_pio0: Force PIO0
 *
 *      Adjust xfer masks of @dev downward.  Note that this function
 *      does not apply the change.  Invoking ata_set_mode() afterwards
 *      will apply the limit.
 *
 *      LOCKING:
 *      Inherited from caller.
 *
 *      RETURNS:
 *      0 on success, negative errno on failure
 */
int ata_down_xfermask_limit(struct ata_device *dev, int force_pio0)
{
        unsigned long xfer_mask;
        int highbit;

        xfer_mask = ata_pack_xfermask(dev->pio_mask, dev->mwdma_mask,
                                      dev->udma_mask);

        if (!xfer_mask)
                goto fail;
        /* don't gear down to MWDMA from UDMA, go directly to PIO */
        if (xfer_mask & ATA_MASK_UDMA)
                xfer_mask &= ~ATA_MASK_MWDMA;

        highbit = fls(xfer_mask) - 1;
        xfer_mask &= ~(1 << highbit);
        if (force_pio0)
                xfer_mask &= 1 << ATA_SHIFT_PIO;
        if (!xfer_mask)
                goto fail;

        ata_unpack_xfermask(xfer_mask, &dev->pio_mask, &dev->mwdma_mask,
                            &dev->udma_mask);

        ata_dev_printk(dev, KERN_WARNING, "limiting speed to %s\n",
                       ata_mode_string(xfer_mask));

        return 0;

 fail:
        return -EINVAL;
}

static int ata_dev_set_mode(struct ata_device *dev)
{
        unsigned int err_mask;
        int rc;

        dev->flags &= ~ATA_DFLAG_PIO;
        if (dev->xfer_shift == ATA_SHIFT_PIO)
                dev->flags |= ATA_DFLAG_PIO;

        err_mask = ata_dev_set_xfermode(dev);
        if (err_mask) {
                ata_dev_printk(dev, KERN_ERR, "failed to set xfermode "
                               "(err_mask=0x%x)\n", err_mask);
                return -EIO;
        }

        rc = ata_dev_revalidate(dev, 0);
        if (rc)
                return rc;

        DPRINTK("xfer_shift=%u, xfer_mode=0x%x\n",
                dev->xfer_shift, (int)dev->xfer_mode);

        ata_dev_printk(dev, KERN_INFO, "configured for %s\n",
                       ata_mode_string(ata_xfer_mode2mask(dev->xfer_mode)));
        return 0;
}

/**
 *      ata_set_mode - Program timings and issue SET FEATURES - XFER
 *      @ap: port on which timings will be programmed
 *      @r_failed_dev: out paramter for failed device
 *
 *      Set ATA device disk transfer mode (PIO3, UDMA6, etc.).  If
 *      ata_set_mode() fails, pointer to the failing device is
 *      returned in @r_failed_dev.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 *      RETURNS:
 *      0 on success, negative errno otherwise
 */
int ata_set_mode(struct ata_port *ap, struct ata_device **r_failed_dev)
{
        struct ata_device *dev;
        int i, rc = 0, used_dma = 0, found = 0;

        /* has private set_mode? */
        if (ap->ops->set_mode) {
                /* FIXME: make ->set_mode handle no device case and
                 * return error code and failing device on failure.
                 */
                for (i = 0; i < ATA_MAX_DEVICES; i++) {
                        if (ata_dev_enabled(&ap->device[i])) {
                                ap->ops->set_mode(ap);
                                break;
                        }
                }
                return 0;
        }

        /* step 1: calculate xfer_mask */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                unsigned int pio_mask, dma_mask;

                dev = &ap->device[i];

                if (!ata_dev_enabled(dev))
                        continue;

                ata_dev_xfermask(dev);

                pio_mask = ata_pack_xfermask(dev->pio_mask, 0, 0);
                dma_mask = ata_pack_xfermask(0, dev->mwdma_mask, dev->udma_mask);
                dev->pio_mode = ata_xfer_mask2mode(pio_mask);
                dev->dma_mode = ata_xfer_mask2mode(dma_mask);

                found = 1;
                if (dev->dma_mode)
                        used_dma = 1;
        }
        if (!found)
                goto out;

        /* step 2: always set host PIO timings */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                dev = &ap->device[i];
                if (!ata_dev_enabled(dev))
                        continue;

                if (!dev->pio_mode) {
                        ata_dev_printk(dev, KERN_WARNING, "no PIO support\n");
                        rc = -EINVAL;
                        goto out;
                }

                dev->xfer_mode = dev->pio_mode;
                dev->xfer_shift = ATA_SHIFT_PIO;
                if (ap->ops->set_piomode)
                        ap->ops->set_piomode(ap, dev);
        }

        /* step 3: set host DMA timings */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                dev = &ap->device[i];

                if (!ata_dev_enabled(dev) || !dev->dma_mode)
                        continue;

                dev->xfer_mode = dev->dma_mode;
                dev->xfer_shift = ata_xfer_mode2shift(dev->dma_mode);
                if (ap->ops->set_dmamode)
                        ap->ops->set_dmamode(ap, dev);
        }

        /* step 4: update devices' xfer mode */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                dev = &ap->device[i];

                if (!ata_dev_enabled(dev))
                        continue;

                rc = ata_dev_set_mode(dev);
                if (rc)
                        goto out;
        }

        /* Record simplex status. If we selected DMA then the other
         * host channels are not permitted to do so.
         */
        if (used_dma && (ap->host_set->flags & ATA_HOST_SIMPLEX))
                ap->host_set->simplex_claimed = 1;

        /* step5: chip specific finalisation */
        if (ap->ops->post_set_mode)
                ap->ops->post_set_mode(ap);

 out:
        if (rc)
                *r_failed_dev = dev;
        return rc;
}

/**
 *      ata_tf_to_host - issue ATA taskfile to host controller
 *      @ap: port to which command is being issued
 *      @tf: ATA taskfile register set
 *
 *      Issues ATA taskfile register set to ATA host controller,
 *      with proper synchronization with interrupt handler and
 *      other threads.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

static inline void ata_tf_to_host(struct ata_port *ap,
                                  const struct ata_taskfile *tf)
{
        ap->ops->tf_load(ap, tf);
        ap->ops->exec_command(ap, tf);
}

/**
 *      ata_busy_sleep - sleep until BSY clears, or timeout
 *      @ap: port containing status register to be polled
 *      @tmout_pat: impatience timeout
 *      @tmout: overall timeout
 *
 *      Sleep until ATA Status register bit BSY clears,
 *      or a timeout occurs.
 *
 *      LOCKING: None.
 */

unsigned int ata_busy_sleep (struct ata_port *ap,
                             unsigned long tmout_pat, unsigned long tmout)
{
        unsigned long timer_start, timeout;
        u8 status;

        status = ata_busy_wait(ap, ATA_BUSY, 300);
        timer_start = jiffies;
        timeout = timer_start + tmout_pat;
        while ((status & ATA_BUSY) && (time_before(jiffies, timeout))) {
                msleep(50);
                status = ata_busy_wait(ap, ATA_BUSY, 3);
        }

        if (status & ATA_BUSY)
                ata_port_printk(ap, KERN_WARNING,
                                "port is slow to respond, please be patient\n");

        timeout = timer_start + tmout;
        while ((status & ATA_BUSY) && (time_before(jiffies, timeout))) {
                msleep(50);
                status = ata_chk_status(ap);
        }

        if (status & ATA_BUSY) {
                ata_port_printk(ap, KERN_ERR, "port failed to respond "
                                "(%lu secs)\n", tmout / HZ);
                return 1;
        }

        return 0;
}

static void ata_bus_post_reset(struct ata_port *ap, unsigned int devmask)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        unsigned int dev0 = devmask & (1 << 0);
        unsigned int dev1 = devmask & (1 << 1);
        unsigned long timeout;

        /* if device 0 was found in ata_devchk, wait for its
         * BSY bit to clear
         */
        if (dev0)
                ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);

        /* if device 1 was found in ata_devchk, wait for
         * register access, then wait for BSY to clear
         */
        timeout = jiffies + ATA_TMOUT_BOOT;
        while (dev1) {
                u8 nsect, lbal;

                ap->ops->dev_select(ap, 1);
                if (ap->flags & ATA_FLAG_MMIO) {
                        nsect = readb((void __iomem *) ioaddr->nsect_addr);
                        lbal = readb((void __iomem *) ioaddr->lbal_addr);
                } else {
                        nsect = inb(ioaddr->nsect_addr);
                        lbal = inb(ioaddr->lbal_addr);
                }
                if ((nsect == 1) && (lbal == 1))
                        break;
                if (time_after(jiffies, timeout)) {
                        dev1 = 0;
                        break;
                }
                msleep(50);     /* give drive a breather */
        }
        if (dev1)
                ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);

        /* is all this really necessary? */
        ap->ops->dev_select(ap, 0);
        if (dev1)
                ap->ops->dev_select(ap, 1);
        if (dev0)
                ap->ops->dev_select(ap, 0);
}

static unsigned int ata_bus_softreset(struct ata_port *ap,
                                      unsigned int devmask)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;

        DPRINTK("ata%u: bus reset via SRST\n", ap->id);

        /* software reset.  causes dev0 to be selected */
        if (ap->flags & ATA_FLAG_MMIO) {
                writeb(ap->ctl, (void __iomem *) ioaddr->ctl_addr);
                udelay(20);     /* FIXME: flush */
                writeb(ap->ctl | ATA_SRST, (void __iomem *) ioaddr->ctl_addr);
                udelay(20);     /* FIXME: flush */
                writeb(ap->ctl, (void __iomem *) ioaddr->ctl_addr);
        } else {
                outb(ap->ctl, ioaddr->ctl_addr);
                udelay(10);
                outb(ap->ctl | ATA_SRST, ioaddr->ctl_addr);
                udelay(10);
                outb(ap->ctl, ioaddr->ctl_addr);
        }

        /* spec mandates ">= 2ms" before checking status.
         * We wait 150ms, because that was the magic delay used for
         * ATAPI devices in Hale Landis's ATADRVR, for the period of time
         * between when the ATA command register is written, and then
         * status is checked.  Because waiting for "a while" before
         * checking status is fine, post SRST, we perform this magic
         * delay here as well.
         *
         * Old drivers/ide uses the 2mS rule and then waits for ready
         */
        msleep(150);

        /* Before we perform post reset processing we want to see if
         * the bus shows 0xFF because the odd clown forgets the D7
         * pulldown resistor.
         */
        if (ata_check_status(ap) == 0xFF) {
                ata_port_printk(ap, KERN_ERR, "SRST failed (status 0xFF)\n");
                return AC_ERR_OTHER;
        }

        ata_bus_post_reset(ap, devmask);

        return 0;
}

/**
 *      ata_bus_reset - reset host port and associated ATA channel
 *      @ap: port to reset
 *
 *      This is typically the first time we actually start issuing
 *      commands to the ATA channel.  We wait for BSY to clear, then
 *      issue EXECUTE DEVICE DIAGNOSTIC command, polling for its
 *      result.  Determine what devices, if any, are on the channel
 *      by looking at the device 0/1 error register.  Look at the signature
 *      stored in each device's taskfile registers, to determine if
 *      the device is ATA or ATAPI.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *      Obtains host_set lock.
 *
 *      SIDE EFFECTS:
 *      Sets ATA_FLAG_DISABLED if bus reset fails.
 */

void ata_bus_reset(struct ata_port *ap)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        unsigned int slave_possible = ap->flags & ATA_FLAG_SLAVE_POSS;
        u8 err;
        unsigned int dev0, dev1 = 0, devmask = 0;

        DPRINTK("ENTER, host %u, port %u\n", ap->id, ap->port_no);

        /* determine if device 0/1 are present */
        if (ap->flags & ATA_FLAG_SATA_RESET)
                dev0 = 1;
        else {
                dev0 = ata_devchk(ap, 0);
                if (slave_possible)
                        dev1 = ata_devchk(ap, 1);
        }

        if (dev0)
                devmask |= (1 << 0);
        if (dev1)
                devmask |= (1 << 1);

        /* select device 0 again */
        ap->ops->dev_select(ap, 0);

        /* issue bus reset */
        if (ap->flags & ATA_FLAG_SRST)
                if (ata_bus_softreset(ap, devmask))
                        goto err_out;

        /*
         * determine by signature whether we have ATA or ATAPI devices
         */
        ap->device[0].class = ata_dev_try_classify(ap, 0, &err);
        if ((slave_possible) && (err != 0x81))
                ap->device[1].class = ata_dev_try_classify(ap, 1, &err);

        /* re-enable interrupts */
        if (ap->ioaddr.ctl_addr)        /* FIXME: hack. create a hook instead */
                ata_irq_on(ap);

        /* is double-select really necessary? */
        if (ap->device[1].class != ATA_DEV_NONE)
                ap->ops->dev_select(ap, 1);
        if (ap->device[0].class != ATA_DEV_NONE)
                ap->ops->dev_select(ap, 0);

        /* if no devices were detected, disable this port */
        if ((ap->device[0].class == ATA_DEV_NONE) &&
            (ap->device[1].class == ATA_DEV_NONE))
                goto err_out;

        if (ap->flags & (ATA_FLAG_SATA_RESET | ATA_FLAG_SRST)) {
                /* set up device control for ATA_FLAG_SATA_RESET */
                if (ap->flags & ATA_FLAG_MMIO)
                        writeb(ap->ctl, (void __iomem *) ioaddr->ctl_addr);
                else
                        outb(ap->ctl, ioaddr->ctl_addr);
        }

        DPRINTK("EXIT\n");
        return;

err_out:
        ata_port_printk(ap, KERN_ERR, "disabling port\n");
        ap->ops->port_disable(ap);

        DPRINTK("EXIT\n");
}

/**
 *      sata_phy_debounce - debounce SATA phy status
 *      @ap: ATA port to debounce SATA phy status for
 *      @params: timing parameters { interval, duratinon, timeout } in msec
 *
 *      Make sure SStatus of @ap reaches stable state, determined by
 *      holding the same value where DET is not 1 for @duration polled
 *      every @interval, before @timeout.  Timeout constraints the
 *      beginning of the stable state.  Because, after hot unplugging,
 *      DET gets stuck at 1 on some controllers, this functions waits
 *      until timeout then returns 0 if DET is stable at 1.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno on failure.
 */
int sata_phy_debounce(struct ata_port *ap, const unsigned long *params)
{
        unsigned long interval_msec = params[0];
        unsigned long duration = params[1] * HZ / 1000;
        unsigned long timeout = jiffies + params[2] * HZ / 1000;
        unsigned long last_jiffies;
        u32 last, cur;
        int rc;

        if ((rc = sata_scr_read(ap, SCR_STATUS, &cur)))
                return rc;
        cur &= 0xf;

        last = cur;
        last_jiffies = jiffies;

        while (1) {
                msleep(interval_msec);
                if ((rc = sata_scr_read(ap, SCR_STATUS, &cur)))
                        return rc;
                cur &= 0xf;

                /* DET stable? */
                if (cur == last) {
                        if (cur == 1 && time_before(jiffies, timeout))
                                continue;
                        if (time_after(jiffies, last_jiffies + duration))
                                return 0;
                        continue;
                }

                /* unstable, start over */
                last = cur;
                last_jiffies = jiffies;

                /* check timeout */
                if (time_after(jiffies, timeout))
                        return -EBUSY;
        }
}

/**
 *      sata_phy_resume - resume SATA phy
 *      @ap: ATA port to resume SATA phy for
 *      @params: timing parameters { interval, duratinon, timeout } in msec
 *
 *      Resume SATA phy of @ap and debounce it.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno on failure.
 */
int sata_phy_resume(struct ata_port *ap, const unsigned long *params)
{
        u32 scontrol;
        int rc;

        if ((rc = sata_scr_read(ap, SCR_CONTROL, &scontrol)))
                return rc;

        scontrol = (scontrol & 0x0f0) | 0x300;

        if ((rc = sata_scr_write(ap, SCR_CONTROL, scontrol)))
                return rc;

        /* Some PHYs react badly if SStatus is pounded immediately
         * after resuming.  Delay 200ms before debouncing.
         */
        msleep(200);

        return sata_phy_debounce(ap, params);
}

static void ata_wait_spinup(struct ata_port *ap)
{
        struct ata_eh_context *ehc = &ap->eh_context;
        unsigned long end, secs;
        int rc;

        /* first, debounce phy if SATA */
        if (ap->cbl == ATA_CBL_SATA) {
                rc = sata_phy_debounce(ap, sata_deb_timing_eh);

                /* if debounced successfully and offline, no need to wait */
                if ((rc == 0 || rc == -EOPNOTSUPP) && ata_port_offline(ap))
                        return;
        }

        /* okay, let's give the drive time to spin up */
        end = ehc->i.hotplug_timestamp + ATA_SPINUP_WAIT * HZ / 1000;
        secs = ((end - jiffies) + HZ - 1) / HZ;

        if (time_after(jiffies, end))
                return;

        if (secs > 5)
                ata_port_printk(ap, KERN_INFO, "waiting for device to spin up "
                                "(%lu secs)\n", secs);

        schedule_timeout_uninterruptible(end - jiffies);
}

/**
 *      ata_std_prereset - prepare for reset
 *      @ap: ATA port to be reset
 *
 *      @ap is about to be reset.  Initialize it.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_std_prereset(struct ata_port *ap)
{
        struct ata_eh_context *ehc = &ap->eh_context;
        const unsigned long *timing;
        int rc;

        /* hotplug? */
        if (ehc->i.flags & ATA_EHI_HOTPLUGGED) {
                if (ap->flags & ATA_FLAG_HRST_TO_RESUME)
                        ehc->i.action |= ATA_EH_HARDRESET;
                if (ap->flags & ATA_FLAG_SKIP_D2H_BSY)
                        ata_wait_spinup(ap);
        }

        /* if we're about to do hardreset, nothing more to do */
        if (ehc->i.action & ATA_EH_HARDRESET)
                return 0;

        /* if SATA, resume phy */
        if (ap->cbl == ATA_CBL_SATA) {
                if (ap->flags & ATA_FLAG_LOADING)
                        timing = sata_deb_timing_boot;
                else
                        timing = sata_deb_timing_eh;

                rc = sata_phy_resume(ap, timing);
                if (rc && rc != -EOPNOTSUPP) {
                        /* phy resume failed */
                        ata_port_printk(ap, KERN_WARNING, "failed to resume "
                                        "link for reset (errno=%d)\n", rc);
                        return rc;
                }
        }

        /* Wait for !BSY if the controller can wait for the first D2H
         * Reg FIS and we don't know that no device is attached.
         */
        if (!(ap->flags & ATA_FLAG_SKIP_D2H_BSY) && !ata_port_offline(ap))
                ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);

        return 0;
}

/**
 *      ata_std_softreset - reset host port via ATA SRST
 *      @ap: port to reset
 *      @classes: resulting classes of attached devices
 *
 *      Reset host port using ATA SRST.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int ata_std_softreset(struct ata_port *ap, unsigned int *classes)
{
        unsigned int slave_possible = ap->flags & ATA_FLAG_SLAVE_POSS;
        unsigned int devmask = 0, err_mask;
        u8 err;

        DPRINTK("ENTER\n");

        if (ata_port_offline(ap)) {
                classes[0] = ATA_DEV_NONE;
                goto out;
        }

        /* determine if device 0/1 are present */
        if (ata_devchk(ap, 0))
                devmask |= (1 << 0);
        if (slave_possible && ata_devchk(ap, 1))
                devmask |= (1 << 1);

        /* select device 0 again */
        ap->ops->dev_select(ap, 0);

        /* issue bus reset */
        DPRINTK("about to softreset, devmask=%x\n", devmask);
        err_mask = ata_bus_softreset(ap, devmask);
        if (err_mask) {
                ata_port_printk(ap, KERN_ERR, "SRST failed (err_mask=0x%x)\n",
                                err_mask);
                return -EIO;
        }

        /* determine by signature whether we have ATA or ATAPI devices */
        classes[0] = ata_dev_try_classify(ap, 0, &err);
        if (slave_possible && err != 0x81)
                classes[1] = ata_dev_try_classify(ap, 1, &err);

 out:
        DPRINTK("EXIT, classes[0]=%u [1]=%u\n", classes[0], classes[1]);
        return 0;
}

/**
 *      sata_std_hardreset - reset host port via SATA phy reset
 *      @ap: port to reset
 *      @class: resulting class of attached device
 *
 *      SATA phy-reset host port using DET bits of SControl register.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, -errno otherwise.
 */
int sata_std_hardreset(struct ata_port *ap, unsigned int *class)
{
        u32 scontrol;
        int rc;

        DPRINTK("ENTER\n");

        if (sata_set_spd_needed(ap)) {
                /* SATA spec says nothing about how to reconfigure
                 * spd.  To be on the safe side, turn off phy during
                 * reconfiguration.  This works for at least ICH7 AHCI
                 * and Sil3124.
                 */
                if ((rc = sata_scr_read(ap, SCR_CONTROL, &scontrol)))
                        return rc;

                scontrol = (scontrol & 0x0f0) | 0x302;

                if ((rc = sata_scr_write(ap, SCR_CONTROL, scontrol)))
                        return rc;

                sata_set_spd(ap);
        }

        /* issue phy wake/reset */
        if ((rc = sata_scr_read(ap, SCR_CONTROL, &scontrol)))
                return rc;

        scontrol = (scontrol & 0x0f0) | 0x301;

        if ((rc = sata_scr_write_flush(ap, SCR_CONTROL, scontrol)))
                return rc;

        /* Couldn't find anything in SATA I/II specs, but AHCI-1.1
         * 10.4.2 says at least 1 ms.
         */
        msleep(1);

        /* bring phy back */
        sata_phy_resume(ap, sata_deb_timing_eh);

        /* TODO: phy layer with polling, timeouts, etc. */
        if (ata_port_offline(ap)) {
                *class = ATA_DEV_NONE;
                DPRINTK("EXIT, link offline\n");
                return 0;
        }

        if (ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT)) {
                ata_port_printk(ap, KERN_ERR,
                                "COMRESET failed (device not ready)\n");
                return -EIO;
        }

        ap->ops->dev_select(ap, 0);     /* probably unnecessary */

        *class = ata_dev_try_classify(ap, 0, NULL);

        DPRINTK("EXIT, class=%u\n", *class);
        return 0;
}

/**
 *      ata_std_postreset - standard postreset callback
 *      @ap: the target ata_port
 *      @classes: classes of attached devices
 *
 *      This function is invoked after a successful reset.  Note that
 *      the device might have been reset more than once using
 *      different reset methods before postreset is invoked.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 */
void ata_std_postreset(struct ata_port *ap, unsigned int *classes)
{
        u32 serror;

        DPRINTK("ENTER\n");

        /* print link status */
        sata_print_link_status(ap);

        /* clear SError */
        if (sata_scr_read(ap, SCR_ERROR, &serror) == 0)
                sata_scr_write(ap, SCR_ERROR, serror);

        /* re-enable interrupts */
        if (!ap->ops->error_handler) {
                /* FIXME: hack. create a hook instead */
                if (ap->ioaddr.ctl_addr)
                        ata_irq_on(ap);
        }

        /* is double-select really necessary? */
        if (classes[0] != ATA_DEV_NONE)
                ap->ops->dev_select(ap, 1);
        if (classes[1] != ATA_DEV_NONE)
                ap->ops->dev_select(ap, 0);

        /* bail out if no device is present */
        if (classes[0] == ATA_DEV_NONE && classes[1] == ATA_DEV_NONE) {
                DPRINTK("EXIT, no device\n");
                return;
        }

        /* set up device control */
        if (ap->ioaddr.ctl_addr) {
                if (ap->flags & ATA_FLAG_MMIO)
                        writeb(ap->ctl, (void __iomem *) ap->ioaddr.ctl_addr);
                else
                        outb(ap->ctl, ap->ioaddr.ctl_addr);
        }

        DPRINTK("EXIT\n");
}

/**
 *      ata_dev_same_device - Determine whether new ID matches configured device
 *      @dev: device to compare against
 *      @new_class: class of the new device
 *      @new_id: IDENTIFY page of the new device
 *
 *      Compare @new_class and @new_id against @dev and determine
 *      whether @dev is the device indicated by @new_class and
 *      @new_id.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      1 if @dev matches @new_class and @new_id, 0 otherwise.
 */
static int ata_dev_same_device(struct ata_device *dev, unsigned int new_class,
                               const u16 *new_id)
{
        const u16 *old_id = dev->id;
        unsigned char model[2][41], serial[2][21];
        u64 new_n_sectors;

        if (dev->class != new_class) {
                ata_dev_printk(dev, KERN_INFO, "class mismatch %d != %d\n",
                               dev->class, new_class);
                return 0;
        }

        ata_id_c_string(old_id, model[0], ATA_ID_PROD_OFS, sizeof(model[0]));
        ata_id_c_string(new_id, model[1], ATA_ID_PROD_OFS, sizeof(model[1]));
        ata_id_c_string(old_id, serial[0], ATA_ID_SERNO_OFS, sizeof(serial[0]));
        ata_id_c_string(new_id, serial[1], ATA_ID_SERNO_OFS, sizeof(serial[1]));
        new_n_sectors = ata_id_n_sectors(new_id);

        if (strcmp(model[0], model[1])) {
                ata_dev_printk(dev, KERN_INFO, "model number mismatch "
                               "'%s' != '%s'\n", model[0], model[1]);
                return 0;
        }

        if (strcmp(serial[0], serial[1])) {
                ata_dev_printk(dev, KERN_INFO, "serial number mismatch "
                               "'%s' != '%s'\n", serial[0], serial[1]);
                return 0;
        }

        if (dev->class == ATA_DEV_ATA && dev->n_sectors != new_n_sectors) {
                ata_dev_printk(dev, KERN_INFO, "n_sectors mismatch "
                               "%llu != %llu\n",
                               (unsigned long long)dev->n_sectors,
                               (unsigned long long)new_n_sectors);
                return 0;
        }

        return 1;
}

/**
 *      ata_dev_revalidate - Revalidate ATA device
 *      @dev: device to revalidate
 *      @post_reset: is this revalidation after reset?
 *
 *      Re-read IDENTIFY page and make sure @dev is still attached to
 *      the port.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, negative errno otherwise
 */
int ata_dev_revalidate(struct ata_device *dev, int post_reset)
{
        unsigned int class = dev->class;
        u16 *id = (void *)dev->ap->sector_buf;
        int rc;

        if (!ata_dev_enabled(dev)) {
                rc = -ENODEV;
                goto fail;
        }

        /* read ID data */
        rc = ata_dev_read_id(dev, &class, post_reset, id);
        if (rc)
                goto fail;

        /* is the device still there? */
        if (!ata_dev_same_device(dev, class, id)) {
                rc = -ENODEV;
                goto fail;
        }

        memcpy(dev->id, id, sizeof(id[0]) * ATA_ID_WORDS);

        /* configure device according to the new ID */
        rc = ata_dev_configure(dev, 0);
        if (rc == 0)
                return 0;

 fail:
        ata_dev_printk(dev, KERN_ERR, "revalidation failed (errno=%d)\n", rc);
        return rc;
}

static const char * const ata_dma_blacklist [] = {
        "WDC AC11000H", NULL,
        "WDC AC22100H", NULL,
        "WDC AC32500H", NULL,
        "WDC AC33100H", NULL,
        "WDC AC31600H", NULL,
        "WDC AC32100H", "24.09P07",
        "WDC AC23200L", "21.10N21",
        "Compaq CRD-8241B",  NULL,
        "CRD-8400B", NULL,
        "CRD-8480B", NULL,
        "CRD-8482B", NULL,
        "CRD-84", NULL,
        "SanDisk SDP3B", NULL,
        "SanDisk SDP3B-64", NULL,
        "SANYO CD-ROM CRD", NULL,
        "HITACHI CDR-8", NULL,
        "HITACHI CDR-8335", NULL,
        "HITACHI CDR-8435", NULL,
        "Toshiba CD-ROM XM-6202B", NULL,
        "TOSHIBA CD-ROM XM-1702BC", NULL,
        "CD-532E-A", NULL,
        "E-IDE CD-ROM CR-840", NULL,
        "CD-ROM Drive/F5A", NULL,
        "WPI CDD-820", NULL,
        "SAMSUNG CD-ROM SC-148C", NULL,
        "SAMSUNG CD-ROM SC", NULL,
        "SanDisk SDP3B-64", NULL,
        "ATAPI CD-ROM DRIVE 40X MAXIMUM",NULL,
        "_NEC DV5800A", NULL,
        "SAMSUNG CD-ROM SN-124", "N001"
};

static int ata_strim(char *s, size_t len)
{
        len = strnlen(s, len);

        /* ATAPI specifies that empty space is blank-filled; remove blanks */
        while ((len > 0) && (s[len - 1] == ' ')) {
                len--;
                s[len] = 0;
        }
        return len;
}

static int ata_dma_blacklisted(const struct ata_device *dev)
{
        unsigned char model_num[40];
        unsigned char model_rev[16];
        unsigned int nlen, rlen;
        int i;

        /* We don't support polling DMA.
         * DMA blacklist those ATAPI devices with CDB-intr (and use PIO)
         * if the LLDD handles only interrupts in the HSM_ST_LAST state.
         */
        if ((dev->ap->flags & ATA_FLAG_PIO_POLLING) &&
            (dev->flags & ATA_DFLAG_CDB_INTR))
                return 1;

        ata_id_string(dev->id, model_num, ATA_ID_PROD_OFS,
                          sizeof(model_num));
        ata_id_string(dev->id, model_rev, ATA_ID_FW_REV_OFS,
                          sizeof(model_rev));
        nlen = ata_strim(model_num, sizeof(model_num));
        rlen = ata_strim(model_rev, sizeof(model_rev));

        for (i = 0; i < ARRAY_SIZE(ata_dma_blacklist); i += 2) {
                if (!strncmp(ata_dma_blacklist[i], model_num, nlen)) {
                        if (ata_dma_blacklist[i+1] == NULL)
                                return 1;
                        if (!strncmp(ata_dma_blacklist[i], model_rev, rlen))
                                return 1;
                }
        }
        return 0;
}

/**
 *      ata_dev_xfermask - Compute supported xfermask of the given device
 *      @dev: Device to compute xfermask for
 *
 *      Compute supported xfermask of @dev and store it in
 *      dev->*_mask.  This function is responsible for applying all
 *      known limits including host controller limits, device
 *      blacklist, etc...
 *
 *      FIXME: The current implementation limits all transfer modes to
 *      the fastest of the lowested device on the port.  This is not
 *      required on most controllers.
 *
 *      LOCKING:
 *      None.
 */
static void ata_dev_xfermask(struct ata_device *dev)
{
        struct ata_port *ap = dev->ap;
        struct ata_host_set *hs = ap->host_set;
        unsigned long xfer_mask;
        int i;

        xfer_mask = ata_pack_xfermask(ap->pio_mask,
                                      ap->mwdma_mask, ap->udma_mask);

        /* Apply cable rule here.  Don't apply it early because when
         * we handle hot plug the cable type can itself change.
         */
        if (ap->cbl == ATA_CBL_PATA40)
                xfer_mask &= ~(0xF8 << ATA_SHIFT_UDMA);

        /* FIXME: Use port-wide xfermask for now */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *d = &ap->device[i];

                if (ata_dev_absent(d))
                        continue;

                if (ata_dev_disabled(d)) {
                        /* to avoid violating device selection timing */
                        xfer_mask &= ata_pack_xfermask(d->pio_mask,
                                                       UINT_MAX, UINT_MAX);
                        continue;
                }

                xfer_mask &= ata_pack_xfermask(d->pio_mask,
                                               d->mwdma_mask, d->udma_mask);
                xfer_mask &= ata_id_xfermask(d->id);
                if (ata_dma_blacklisted(d))
                        xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
        }

        if (ata_dma_blacklisted(dev))
                ata_dev_printk(dev, KERN_WARNING,
                               "device is on DMA blacklist, disabling DMA\n");

        if (hs->flags & ATA_HOST_SIMPLEX) {
                if (hs->simplex_claimed)
                        xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
        }

        if (ap->ops->mode_filter)
                xfer_mask = ap->ops->mode_filter(ap, dev, xfer_mask);

        ata_unpack_xfermask(xfer_mask, &dev->pio_mask,
                            &dev->mwdma_mask, &dev->udma_mask);
}

/**
 *      ata_dev_set_xfermode - Issue SET FEATURES - XFER MODE command
 *      @dev: Device to which command will be sent
 *
 *      Issue SET FEATURES - XFER MODE command to device @dev
 *      on port @ap.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 *      RETURNS:
 *      0 on success, AC_ERR_* mask otherwise.
 */

static unsigned int ata_dev_set_xfermode(struct ata_device *dev)
{
        struct ata_taskfile tf;
        unsigned int err_mask;

        /* set up set-features taskfile */
        DPRINTK("set features - xfer mode\n");

        ata_tf_init(dev, &tf);
        tf.command = ATA_CMD_SET_FEATURES;
        tf.feature = SETFEATURES_XFER;
        tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        tf.protocol = ATA_PROT_NODATA;
        tf.nsect = dev->xfer_mode;

        err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0);

        DPRINTK("EXIT, err_mask=%x\n", err_mask);
        return err_mask;
}

/**
 *      ata_dev_init_params - Issue INIT DEV PARAMS command
 *      @dev: Device to which command will be sent
 *      @heads: Number of heads (taskfile parameter)
 *      @sectors: Number of sectors (taskfile parameter)
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      0 on success, AC_ERR_* mask otherwise.
 */
static unsigned int ata_dev_init_params(struct ata_device *dev,
                                        u16 heads, u16 sectors)
{
        struct ata_taskfile tf;
        unsigned int err_mask;

        /* Number of sectors per track 1-255. Number of heads 1-16 */
        if (sectors < 1 || sectors > 255 || heads < 1 || heads > 16)
                return AC_ERR_INVALID;

        /* set up init dev params taskfile */
        DPRINTK("init dev params \n");

        ata_tf_init(dev, &tf);
        tf.command = ATA_CMD_INIT_DEV_PARAMS;
        tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        tf.protocol = ATA_PROT_NODATA;
        tf.nsect = sectors;
        tf.device |= (heads - 1) & 0x0f; /* max head = num. of heads - 1 */

        err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0);

        DPRINTK("EXIT, err_mask=%x\n", err_mask);
        return err_mask;
}

/**
 *      ata_sg_clean - Unmap DMA memory associated with command
 *      @qc: Command containing DMA memory to be released
 *
 *      Unmap all mapped DMA memory associated with this command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

static void ata_sg_clean(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scatterlist *sg = qc->__sg;
        int dir = qc->dma_dir;
        void *pad_buf = NULL;

        WARN_ON(!(qc->flags & ATA_QCFLAG_DMAMAP));
        WARN_ON(sg == NULL);

        if (qc->flags & ATA_QCFLAG_SINGLE)
                WARN_ON(qc->n_elem > 1);

        VPRINTK("unmapping %u sg elements\n", qc->n_elem);

        /* if we padded the buffer out to 32-bit bound, and data
         * xfer direction is from-device, we must copy from the
         * pad buffer back into the supplied buffer
         */
        if (qc->pad_len && !(qc->tf.flags & ATA_TFLAG_WRITE))
                pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ);

        if (qc->flags & ATA_QCFLAG_SG) {
                if (qc->n_elem)
                        dma_unmap_sg(ap->dev, sg, qc->n_elem, dir);
                /* restore last sg */
                sg[qc->orig_n_elem - 1].length += qc->pad_len;
                if (pad_buf) {
                        struct scatterlist *psg = &qc->pad_sgent;
                        void *addr = kmap_atomic(psg->page, KM_IRQ0);
                        memcpy(addr + psg->offset, pad_buf, qc->pad_len);
                        kunmap_atomic(addr, KM_IRQ0);
                }
        } else {
                if (qc->n_elem)
                        dma_unmap_single(ap->dev,
                                sg_dma_address(&sg[0]), sg_dma_len(&sg[0]),
                                dir);
                /* restore sg */
                sg->length += qc->pad_len;
                if (pad_buf)
                        memcpy(qc->buf_virt + sg->length - qc->pad_len,
                               pad_buf, qc->pad_len);
        }

        qc->flags &= ~ATA_QCFLAG_DMAMAP;
        qc->__sg = NULL;
}

/**
 *      ata_fill_sg - Fill PCI IDE PRD table
 *      @qc: Metadata associated with taskfile to be transferred
 *
 *      Fill PCI IDE PRD (scatter-gather) table with segments
 *      associated with the current disk command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 */
static void ata_fill_sg(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scatterlist *sg;
        unsigned int idx;

        WARN_ON(qc->__sg == NULL);
        WARN_ON(qc->n_elem == 0 && qc->pad_len == 0);

        idx = 0;
        ata_for_each_sg(sg, qc) {
                u32 addr, offset;
                u32 sg_len, len;

                /* determine if physical DMA addr spans 64K boundary.
                 * Note h/w doesn't support 64-bit, so we unconditionally
                 * truncate dma_addr_t to u32.
                 */
                addr = (u32) sg_dma_address(sg);
                sg_len = sg_dma_len(sg);

                while (sg_len) {
                        offset = addr & 0xffff;
                        len = sg_len;
                        if ((offset + sg_len) > 0x10000)
                                len = 0x10000 - offset;

                        ap->prd[idx].addr = cpu_to_le32(addr);
                        ap->prd[idx].flags_len = cpu_to_le32(len & 0xffff);
                        VPRINTK("PRD[%u] = (0x%X, 0x%X)\n", idx, addr, len);

                        idx++;
                        sg_len -= len;
                        addr += len;
                }
        }

        if (idx)
                ap->prd[idx - 1].flags_len |= cpu_to_le32(ATA_PRD_EOT);
}
/**
 *      ata_check_atapi_dma - Check whether ATAPI DMA can be supported
 *      @qc: Metadata associated with taskfile to check
 *
 *      Allow low-level driver to filter ATA PACKET commands, returning
 *      a status indicating whether or not it is OK to use DMA for the
 *      supplied PACKET command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS: 0 when ATAPI DMA can be used
 *               nonzero otherwise
 */
int ata_check_atapi_dma(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        int rc = 0; /* Assume ATAPI DMA is OK by default */

        if (ap->ops->check_atapi_dma)
                rc = ap->ops->check_atapi_dma(qc);

        return rc;
}
/**
 *      ata_qc_prep - Prepare taskfile for submission
 *      @qc: Metadata associated with taskfile to be prepared
 *
 *      Prepare ATA taskfile for submission.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_qc_prep(struct ata_queued_cmd *qc)
{
        if (!(qc->flags & ATA_QCFLAG_DMAMAP))
                return;

        ata_fill_sg(qc);
}

void ata_noop_qc_prep(struct ata_queued_cmd *qc) { }

/**
 *      ata_sg_init_one - Associate command with memory buffer
 *      @qc: Command to be associated
 *      @buf: Memory buffer
 *      @buflen: Length of memory buffer, in bytes.
 *
 *      Initialize the data-related elements of queued_cmd @qc
 *      to point to a single memory buffer, @buf of byte length @buflen.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

void ata_sg_init_one(struct ata_queued_cmd *qc, void *buf, unsigned int buflen)
{
        struct scatterlist *sg;

        qc->flags |= ATA_QCFLAG_SINGLE;

        memset(&qc->sgent, 0, sizeof(qc->sgent));
        qc->__sg = &qc->sgent;
        qc->n_elem = 1;
        qc->orig_n_elem = 1;
        qc->buf_virt = buf;
        qc->nbytes = buflen;

        sg = qc->__sg;
        sg_init_one(sg, buf, buflen);
}

/**
 *      ata_sg_init - Associate command with scatter-gather table.
 *      @qc: Command to be associated
 *      @sg: Scatter-gather table.
 *      @n_elem: Number of elements in s/g table.
 *
 *      Initialize the data-related elements of queued_cmd @qc
 *      to point to a scatter-gather table @sg, containing @n_elem
 *      elements.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

void ata_sg_init(struct ata_queued_cmd *qc, struct scatterlist *sg,
                 unsigned int n_elem)
{
        qc->flags |= ATA_QCFLAG_SG;
        qc->__sg = sg;
        qc->n_elem = n_elem;
        qc->orig_n_elem = n_elem;
}

/**
 *      ata_sg_setup_one - DMA-map the memory buffer associated with a command.
 *      @qc: Command with memory buffer to be mapped.
 *
 *      DMA-map the memory buffer associated with queued_cmd @qc.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, negative on error.
 */

static int ata_sg_setup_one(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        int dir = qc->dma_dir;
        struct scatterlist *sg = qc->__sg;
        dma_addr_t dma_address;
        int trim_sg = 0;

        /* we must lengthen transfers to end on a 32-bit boundary */
        qc->pad_len = sg->length & 3;
        if (qc->pad_len) {
                void *pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ);
                struct scatterlist *psg = &qc->pad_sgent;

                WARN_ON(qc->dev->class != ATA_DEV_ATAPI);

                memset(pad_buf, 0, ATA_DMA_PAD_SZ);

                if (qc->tf.flags & ATA_TFLAG_WRITE)
                        memcpy(pad_buf, qc->buf_virt + sg->length - qc->pad_len,
                               qc->pad_len);

                sg_dma_address(psg) = ap->pad_dma + (qc->tag * ATA_DMA_PAD_SZ);
                sg_dma_len(psg) = ATA_DMA_PAD_SZ;
                /* trim sg */
                sg->length -= qc->pad_len;
                if (sg->length == 0)
                        trim_sg = 1;

                DPRINTK("padding done, sg->length=%u pad_len=%u\n",
                        sg->length, qc->pad_len);
        }

        if (trim_sg) {
                qc->n_elem--;
                goto skip_map;
        }

        dma_address = dma_map_single(ap->dev, qc->buf_virt,
                                     sg->length, dir);
        if (dma_mapping_error(dma_address)) {
                /* restore sg */
                sg->length += qc->pad_len;
                return -1;
        }

        sg_dma_address(sg) = dma_address;
        sg_dma_len(sg) = sg->length;

skip_map:
        DPRINTK("mapped buffer of %d bytes for %s\n", sg_dma_len(sg),
                qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");

        return 0;
}

/**
 *      ata_sg_setup - DMA-map the scatter-gather table associated with a command.
 *      @qc: Command with scatter-gather table to be mapped.
 *
 *      DMA-map the scatter-gather table associated with queued_cmd @qc.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, negative on error.
 *
 */

static int ata_sg_setup(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scatterlist *sg = qc->__sg;
        struct scatterlist *lsg = &sg[qc->n_elem - 1];
        int n_elem, pre_n_elem, dir, trim_sg = 0;

        VPRINTK("ENTER, ata%u\n", ap->id);
        WARN_ON(!(qc->flags & ATA_QCFLAG_SG));

        /* we must lengthen transfers to end on a 32-bit boundary */
        qc->pad_len = lsg->length & 3;
        if (qc->pad_len) {
                void *pad_buf = ap->pad + (qc->tag * ATA_DMA_PAD_SZ);
                struct scatterlist *psg = &qc->pad_sgent;
                unsigned int offset;

                WARN_ON(qc->dev->class != ATA_DEV_ATAPI);

                memset(pad_buf, 0, ATA_DMA_PAD_SZ);

                /*
                 * psg->page/offset are used to copy to-be-written
                 * data in this function or read data in ata_sg_clean.
                 */
                offset = lsg->offset + lsg->length - qc->pad_len;
                psg->page = nth_page(lsg->page, offset >> PAGE_SHIFT);
                psg->offset = offset_in_page(offset);

                if (qc->tf.flags & ATA_TFLAG_WRITE) {
                        void *addr = kmap_atomic(psg->page, KM_IRQ0);
                        memcpy(pad_buf, addr + psg->offset, qc->pad_len);
                        kunmap_atomic(addr, KM_IRQ0);
                }

                sg_dma_address(psg) = ap->pad_dma + (qc->tag * ATA_DMA_PAD_SZ);
                sg_dma_len(psg) = ATA_DMA_PAD_SZ;
                /* trim last sg */
                lsg->length -= qc->pad_len;
                if (lsg->length == 0)
                        trim_sg = 1;

                DPRINTK("padding done, sg[%d].length=%u pad_len=%u\n",
                        qc->n_elem - 1, lsg->length, qc->pad_len);
        }

        pre_n_elem = qc->n_elem;
        if (trim_sg && pre_n_elem)
                pre_n_elem--;

        if (!pre_n_elem) {
                n_elem = 0;
                goto skip_map;
        }

        dir = qc->dma_dir;
        n_elem = dma_map_sg(ap->dev, sg, pre_n_elem, dir);
        if (n_elem < 1) {
                /* restore last sg */
                lsg->length += qc->pad_len;
                return -1;
        }

        DPRINTK("%d sg elements mapped\n", n_elem);

skip_map:
        qc->n_elem = n_elem;

        return 0;
}

/**
 *      swap_buf_le16 - swap halves of 16-bit words in place
 *      @buf:  Buffer to swap
 *      @buf_words:  Number of 16-bit words in buffer.
 *
 *      Swap halves of 16-bit words if needed to convert from
 *      little-endian byte order to native cpu byte order, or
 *      vice-versa.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
void swap_buf_le16(u16 *buf, unsigned int buf_words)
{
#ifdef __BIG_ENDIAN
        unsigned int i;

        for (i = 0; i < buf_words; i++)
                buf[i] = le16_to_cpu(buf[i]);
#endif /* __BIG_ENDIAN */
}

/**
 *      ata_mmio_data_xfer - Transfer data by MMIO
 *      @adev: device for this I/O
 *      @buf: data buffer
 *      @buflen: buffer length
 *      @write_data: read/write
 *
 *      Transfer data from/to the device data register by MMIO.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

void ata_mmio_data_xfer(struct ata_device *adev, unsigned char *buf,
                        unsigned int buflen, int write_data)
{
        struct ata_port *ap = adev->ap;
        unsigned int i;
        unsigned int words = buflen >> 1;
        u16 *buf16 = (u16 *) buf;
        void __iomem *mmio = (void __iomem *)ap->ioaddr.data_addr;

        /* Transfer multiple of 2 bytes */
        if (write_data) {
                for (i = 0; i < words; i++)
                        writew(le16_to_cpu(buf16[i]), mmio);
        } else {
                for (i = 0; i < words; i++)
                        buf16[i] = cpu_to_le16(readw(mmio));
        }

        /* Transfer trailing 1 byte, if any. */
        if (unlikely(buflen & 0x01)) {
                u16 align_buf[1] = { 0 };
                unsigned char *trailing_buf = buf + buflen - 1;

                if (write_data) {
                        memcpy(align_buf, trailing_buf, 1);
                        writew(le16_to_cpu(align_buf[0]), mmio);
                } else {
                        align_buf[0] = cpu_to_le16(readw(mmio));
                        memcpy(trailing_buf, align_buf, 1);
                }
        }
}

/**
 *      ata_pio_data_xfer - Transfer data by PIO
 *      @adev: device to target
 *      @buf: data buffer
 *      @buflen: buffer length
 *      @write_data: read/write
 *
 *      Transfer data from/to the device data register by PIO.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

void ata_pio_data_xfer(struct ata_device *adev, unsigned char *buf,
                       unsigned int buflen, int write_data)
{
        struct ata_port *ap = adev->ap;
        unsigned int words = buflen >> 1;

        /* Transfer multiple of 2 bytes */
        if (write_data)
                outsw(ap->ioaddr.data_addr, buf, words);
        else
                insw(ap->ioaddr.data_addr, buf, words);

        /* Transfer trailing 1 byte, if any. */
        if (unlikely(buflen & 0x01)) {
                u16 align_buf[1] = { 0 };
                unsigned char *trailing_buf = buf + buflen - 1;

                if (write_data) {
                        memcpy(align_buf, trailing_buf, 1);
                        outw(le16_to_cpu(align_buf[0]), ap->ioaddr.data_addr);
                } else {
                        align_buf[0] = cpu_to_le16(inw(ap->ioaddr.data_addr));
                        memcpy(trailing_buf, align_buf, 1);
                }
        }
}

/**
 *      ata_pio_data_xfer_noirq - Transfer data by PIO
 *      @adev: device to target
 *      @buf: data buffer
 *      @buflen: buffer length
 *      @write_data: read/write
 *
 *      Transfer data from/to the device data register by PIO. Do the
 *      transfer with interrupts disabled.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

void ata_pio_data_xfer_noirq(struct ata_device *adev, unsigned char *buf,
                                    unsigned int buflen, int write_data)
{
        unsigned long flags;
        local_irq_save(flags);
        ata_pio_data_xfer(adev, buf, buflen, write_data);
        local_irq_restore(flags);
}


/**
 *      ata_pio_sector - Transfer ATA_SECT_SIZE (512 bytes) of data.
 *      @qc: Command on going
 *
 *      Transfer ATA_SECT_SIZE of data from/to the ATA device.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void ata_pio_sector(struct ata_queued_cmd *qc)
{
        int do_write = (qc->tf.flags & ATA_TFLAG_WRITE);
        struct scatterlist *sg = qc->__sg;
        struct ata_port *ap = qc->ap;
        struct page *page;
        unsigned int offset;
        unsigned char *buf;

        if (qc->cursect == (qc->nsect - 1))
                ap->hsm_task_state = HSM_ST_LAST;

        page = sg[qc->cursg].page;
        offset = sg[qc->cursg].offset + qc->cursg_ofs * ATA_SECT_SIZE;

        /* get the current page and offset */
        page = nth_page(page, (offset >> PAGE_SHIFT));
        offset %= PAGE_SIZE;

        DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");

        if (PageHighMem(page)) {
                unsigned long flags;

                /* FIXME: use a bounce buffer */
                local_irq_save(flags);
                buf = kmap_atomic(page, KM_IRQ0);

                /* do the actual data transfer */
                ap->ops->data_xfer(qc->dev, buf + offset, ATA_SECT_SIZE, do_write);

                kunmap_atomic(buf, KM_IRQ0);
                local_irq_restore(flags);
        } else {
                buf = page_address(page);
                ap->ops->data_xfer(qc->dev, buf + offset, ATA_SECT_SIZE, do_write);
        }

        qc->cursect++;
        qc->cursg_ofs++;

        if ((qc->cursg_ofs * ATA_SECT_SIZE) == (&sg[qc->cursg])->length) {
                qc->cursg++;
                qc->cursg_ofs = 0;
        }
}

/**
 *      ata_pio_sectors - Transfer one or many 512-byte sectors.
 *      @qc: Command on going
 *
 *      Transfer one or many ATA_SECT_SIZE of data from/to the
 *      ATA device for the DRQ request.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void ata_pio_sectors(struct ata_queued_cmd *qc)
{
        if (is_multi_taskfile(&qc->tf)) {
                /* READ/WRITE MULTIPLE */
                unsigned int nsect;

                WARN_ON(qc->dev->multi_count == 0);

                nsect = min(qc->nsect - qc->cursect, qc->dev->multi_count);
                while (nsect--)
                        ata_pio_sector(qc);
        } else
                ata_pio_sector(qc);
}

/**
 *      atapi_send_cdb - Write CDB bytes to hardware
 *      @ap: Port to which ATAPI device is attached.
 *      @qc: Taskfile currently active
 *
 *      When device has indicated its readiness to accept
 *      a CDB, this function is called.  Send the CDB.
 *
 *      LOCKING:
 *      caller.
 */

static void atapi_send_cdb(struct ata_port *ap, struct ata_queued_cmd *qc)
{
        /* send SCSI cdb */
        DPRINTK("send cdb\n");
        WARN_ON(qc->dev->cdb_len < 12);

        ap->ops->data_xfer(qc->dev, qc->cdb, qc->dev->cdb_len, 1);
        ata_altstatus(ap); /* flush */

        switch (qc->tf.protocol) {
        case ATA_PROT_ATAPI:
                ap->hsm_task_state = HSM_ST;
                break;
        case ATA_PROT_ATAPI_NODATA:
                ap->hsm_task_state = HSM_ST_LAST;
                break;
        case ATA_PROT_ATAPI_DMA:
                ap->hsm_task_state = HSM_ST_LAST;
                /* initiate bmdma */
                ap->ops->bmdma_start(qc);
                break;
        }
}

/**
 *      __atapi_pio_bytes - Transfer data from/to the ATAPI device.
 *      @qc: Command on going
 *      @bytes: number of bytes
 *
 *      Transfer Transfer data from/to the ATAPI device.
 *
 *      LOCKING:
 *      Inherited from caller.
 *
 */

static void __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
{
        int do_write = (qc->tf.flags & ATA_TFLAG_WRITE);
        struct scatterlist *sg = qc->__sg;
        struct ata_port *ap = qc->ap;
        struct page *page;
        unsigned char *buf;
        unsigned int offset, count;

        if (qc->curbytes + bytes >= qc->nbytes)
                ap->hsm_task_state = HSM_ST_LAST;

next_sg:
        if (unlikely(qc->cursg >= qc->n_elem)) {
                /*
                 * The end of qc->sg is reached and the device expects
                 * more data to transfer. In order not to overrun qc->sg
                 * and fulfill length specified in the byte count register,
                 *    - for read case, discard trailing data from the device
                 *    - for write case, padding zero data to the device
                 */
                u16 pad_buf[1] = { 0 };
                unsigned int words = bytes >> 1;
                unsigned int i;

                if (words) /* warning if bytes > 1 */
                        ata_dev_printk(qc->dev, KERN_WARNING,
                                       "%u bytes trailing data\n", bytes);

                for (i = 0; i < words; i++)
                        ap->ops->data_xfer(qc->dev, (unsigned char*)pad_buf, 2, do_write);

                ap->hsm_task_state = HSM_ST_LAST;
                return;
        }

        sg = &qc->__sg[qc->cursg];

        page = sg->page;
        offset = sg->offset + qc->cursg_ofs;

        /* get the current page and offset */
        page = nth_page(page, (offset >> PAGE_SHIFT));
        offset %= PAGE_SIZE;

        /* don't overrun current sg */
        count = min(sg->length - qc->cursg_ofs, bytes);

        /* don't cross page boundaries */
        count = min(count, (unsigned int)PAGE_SIZE - offset);

        DPRINTK("data %s\n", qc->tf.flags & ATA_TFLAG_WRITE ? "write" : "read");

        if (PageHighMem(page)) {
                unsigned long flags;

                /* FIXME: use bounce buffer */
                local_irq_save(flags);
                buf = kmap_atomic(page, KM_IRQ0);

                /* do the actual data transfer */
                ap->ops->data_xfer(qc->dev,  buf + offset, count, do_write);

                kunmap_atomic(buf, KM_IRQ0);
                local_irq_restore(flags);
        } else {
                buf = page_address(page);
                ap->ops->data_xfer(qc->dev,  buf + offset, count, do_write);
        }

        bytes -= count;
        qc->curbytes += count;
        qc->cursg_ofs += count;

        if (qc->cursg_ofs == sg->length) {
                qc->cursg++;
                qc->cursg_ofs = 0;
        }

        if (bytes)
                goto next_sg;
}

/**
 *      atapi_pio_bytes - Transfer data from/to the ATAPI device.
 *      @qc: Command on going
 *
 *      Transfer Transfer data from/to the ATAPI device.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void atapi_pio_bytes(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct ata_device *dev = qc->dev;
        unsigned int ireason, bc_lo, bc_hi, bytes;
        int i_write, do_write = (qc->tf.flags & ATA_TFLAG_WRITE) ? 1 : 0;

        /* Abuse qc->result_tf for temp storage of intermediate TF
         * here to save some kernel stack usage.
         * For normal completion, qc->result_tf is not relevant. For
         * error, qc->result_tf is later overwritten by ata_qc_complete().
         * So, the correctness of qc->result_tf is not affected.
         */
        ap->ops->tf_read(ap, &qc->result_tf);
        ireason = qc->result_tf.nsect;
        bc_lo = qc->result_tf.lbam;
        bc_hi = qc->result_tf.lbah;
        bytes = (bc_hi << 8) | bc_lo;

        /* shall be cleared to zero, indicating xfer of data */
        if (ireason & (1 << 0))
                goto err_out;

        /* make sure transfer direction matches expected */
        i_write = ((ireason & (1 << 1)) == 0) ? 1 : 0;
        if (do_write != i_write)
                goto err_out;

        VPRINTK("ata%u: xfering %d bytes\n", ap->id, bytes);

        __atapi_pio_bytes(qc, bytes);

        return;

err_out:
        ata_dev_printk(dev, KERN_INFO, "ATAPI check failed\n");
        qc->err_mask |= AC_ERR_HSM;
        ap->hsm_task_state = HSM_ST_ERR;
}

/**
 *      ata_hsm_ok_in_wq - Check if the qc can be handled in the workqueue.
 *      @ap: the target ata_port
 *      @qc: qc on going
 *
 *      RETURNS:
 *      1 if ok in workqueue, 0 otherwise.
 */

static inline int ata_hsm_ok_in_wq(struct ata_port *ap, struct ata_queued_cmd *qc)
{
        if (qc->tf.flags & ATA_TFLAG_POLLING)
                return 1;

        if (ap->hsm_task_state == HSM_ST_FIRST) {
                if (qc->tf.protocol == ATA_PROT_PIO &&
                    (qc->tf.flags & ATA_TFLAG_WRITE))
                    return 1;

                if (is_atapi_taskfile(&qc->tf) &&
                    !(qc->dev->flags & ATA_DFLAG_CDB_INTR))
                        return 1;
        }

        return 0;
}

/**
 *      ata_hsm_qc_complete - finish a qc running on standard HSM
 *      @qc: Command to complete
 *      @in_wq: 1 if called from workqueue, 0 otherwise
 *
 *      Finish @qc which is running on standard HSM.
 *
 *      LOCKING:
 *      If @in_wq is zero, spin_lock_irqsave(host_set lock).
 *      Otherwise, none on entry and grabs host lock.
 */
static void ata_hsm_qc_complete(struct ata_queued_cmd *qc, int in_wq)
{
        struct ata_port *ap = qc->ap;
        unsigned long flags;

        if (ap->ops->error_handler) {
                if (in_wq) {
                        spin_lock_irqsave(ap->lock, flags);

                        /* EH might have kicked in while host_set lock
                         * is released.
                         */
                        qc = ata_qc_from_tag(ap, qc->tag);
                        if (qc) {
                                if (likely(!(qc->err_mask & AC_ERR_HSM))) {
                                        ata_irq_on(ap);
                                        ata_qc_complete(qc);
                                } else
                                        ata_port_freeze(ap);
                        }

                        spin_unlock_irqrestore(ap->lock, flags);
                } else {
                        if (likely(!(qc->err_mask & AC_ERR_HSM)))
                                ata_qc_complete(qc);
                        else
                                ata_port_freeze(ap);
                }
        } else {
                if (in_wq) {
                        spin_lock_irqsave(ap->lock, flags);
                        ata_irq_on(ap);
                        ata_qc_complete(qc);
                        spin_unlock_irqrestore(ap->lock, flags);
                } else
                        ata_qc_complete(qc);
        }

        ata_altstatus(ap); /* flush */
}

/**
 *      ata_hsm_move - move the HSM to the next state.
 *      @ap: the target ata_port
 *      @qc: qc on going
 *      @status: current device status
 *      @in_wq: 1 if called from workqueue, 0 otherwise
 *
 *      RETURNS:
 *      1 when poll next status needed, 0 otherwise.
 */
int ata_hsm_move(struct ata_port *ap, struct ata_queued_cmd *qc,
                 u8 status, int in_wq)
{
        unsigned long flags = 0;
        int poll_next;

        WARN_ON((qc->flags & ATA_QCFLAG_ACTIVE) == 0);

        /* Make sure ata_qc_issue_prot() does not throw things
         * like DMA polling into the workqueue. Notice that
         * in_wq is not equivalent to (qc->tf.flags & ATA_TFLAG_POLLING).
         */
        WARN_ON(in_wq != ata_hsm_ok_in_wq(ap, qc));

fsm_start:
        DPRINTK("ata%u: protocol %d task_state %d (dev_stat 0x%X)\n",
                ap->id, qc->tf.protocol, ap->hsm_task_state, status);

        switch (ap->hsm_task_state) {
        case HSM_ST_FIRST:
                /* Send first data block or PACKET CDB */

                /* If polling, we will stay in the work queue after
                 * sending the data. Otherwise, interrupt handler
                 * takes over after sending the data.
                 */
                poll_next = (qc->tf.flags & ATA_TFLAG_POLLING);

                /* check device status */
                if (unlikely((status & ATA_DRQ) == 0)) {
                        /* handle BSY=0, DRQ=0 as error */
                        if (likely(status & (ATA_ERR | ATA_DF)))
                                /* device stops HSM for abort/error */
                                qc->err_mask |= AC_ERR_DEV;
                        else
                                /* HSM violation. Let EH handle this */
                                qc->err_mask |= AC_ERR_HSM;

                        ap->hsm_task_state = HSM_ST_ERR;
                        goto fsm_start;
                }

                /* Device should not ask for data transfer (DRQ=1)
                 * when it finds something wrong.
                 * We ignore DRQ here and stop the HSM by
                 * changing hsm_task_state to HSM_ST_ERR and
                 * let the EH abort the command or reset the device.
                 */
                if (unlikely(status & (ATA_ERR | ATA_DF))) {
                        printk(KERN_WARNING "ata%d: DRQ=1 with device error, dev_stat 0x%X\n",
                               ap->id, status);
                        qc->err_mask |= AC_ERR_HSM;
                        ap->hsm_task_state = HSM_ST_ERR;
                        goto fsm_start;
                }

                /* Send the CDB (atapi) or the first data block (ata pio out).
                 * During the state transition, interrupt handler shouldn't
                 * be invoked before the data transfer is complete and
                 * hsm_task_state is changed. Hence, the following locking.
                 */
                if (in_wq)
                        spin_lock_irqsave(ap->lock, flags);

                if (qc->tf.protocol == ATA_PROT_PIO) {
                        /* PIO data out protocol.
                         * send first data block.
                         */

                        /* ata_pio_sectors() might change the state
                         * to HSM_ST_LAST. so, the state is changed here
                         * before ata_pio_sectors().
                         */
                        ap->hsm_task_state = HSM_ST;
                        ata_pio_sectors(qc);
                        ata_altstatus(ap); /* flush */
                } else
                        /* send CDB */
                        atapi_send_cdb(ap, qc);

                if (in_wq)
                        spin_unlock_irqrestore(ap->lock, flags);

                /* if polling, ata_pio_task() handles the rest.
                 * otherwise, interrupt handler takes over from here.
                 */
                break;

        case HSM_ST:
                /* complete command or read/write the data register */
                if (qc->tf.protocol == ATA_PROT_ATAPI) {
                        /* ATAPI PIO protocol */
                        if ((status & ATA_DRQ) == 0) {
                                /* No more data to transfer or device error.
                                 * Device error will be tagged in HSM_ST_LAST.
                                 */
                                ap->hsm_task_state = HSM_ST_LAST;
                                goto fsm_start;
                        }

                        /* Device should not ask for data transfer (DRQ=1)
                         * when it finds something wrong.
                         * We ignore DRQ here and stop the HSM by
                         * changing hsm_task_state to HSM_ST_ERR and
                         * let the EH abort the command or reset the device.
                         */
                        if (unlikely(status & (ATA_ERR | ATA_DF))) {
                                printk(KERN_WARNING "ata%d: DRQ=1 with device error, dev_stat 0x%X\n",
                                       ap->id, status);
                                qc->err_mask |= AC_ERR_HSM;
                                ap->hsm_task_state = HSM_ST_ERR;
                                goto fsm_start;
                        }

                        atapi_pio_bytes(qc);

                        if (unlikely(ap->hsm_task_state == HSM_ST_ERR))
                                /* bad ireason reported by device */
                                goto fsm_start;

                } else {
                        /* ATA PIO protocol */
                        if (unlikely((status & ATA_DRQ) == 0)) {
                                /* handle BSY=0, DRQ=0 as error */
                                if (likely(status & (ATA_ERR | ATA_DF)))
                                        /* device stops HSM for abort/error */
                                        qc->err_mask |= AC_ERR_DEV;
                                else
                                        /* HSM violation. Let EH handle this */
                                        qc->err_mask |= AC_ERR_HSM;

                                ap->hsm_task_state = HSM_ST_ERR;
                                goto fsm_start;
                        }

                        /* For PIO reads, some devices may ask for
                         * data transfer (DRQ=1) alone with ERR=1.
                         * We respect DRQ here and transfer one
                         * block of junk data before changing the
                         * hsm_task_state to HSM_ST_ERR.
                         *
                         * For PIO writes, ERR=1 DRQ=1 doesn't make
                         * sense since the data block has been
                         * transferred to the device.
                         */
                        if (unlikely(status & (ATA_ERR | ATA_DF))) {
                                /* data might be corrputed */
                                qc->err_mask |= AC_ERR_DEV;

                                if (!(qc->tf.flags & ATA_TFLAG_WRITE)) {
                                        ata_pio_sectors(qc);
                                        ata_altstatus(ap);
                                        status = ata_wait_idle(ap);
                                }

                                if (status & (ATA_BUSY | ATA_DRQ))
                                        qc->err_mask |= AC_ERR_HSM;

                                /* ata_pio_sectors() might change the
                                 * state to HSM_ST_LAST. so, the state
                                 * is changed after ata_pio_sectors().
                                 */
                                ap->hsm_task_state = HSM_ST_ERR;
                                goto fsm_start;
                        }

                        ata_pio_sectors(qc);

                        if (ap->hsm_task_state == HSM_ST_LAST &&
                            (!(qc->tf.flags & ATA_TFLAG_WRITE))) {
                                /* all data read */
                                ata_altstatus(ap);
                                status = ata_wait_idle(ap);
                                goto fsm_start;
                        }
                }

                ata_altstatus(ap); /* flush */
                poll_next = 1;
                break;

        case HSM_ST_LAST:
                if (unlikely(!ata_ok(status))) {
                        qc->err_mask |= __ac_err_mask(status);
                        ap->hsm_task_state = HSM_ST_ERR;
                        goto fsm_start;
                }

                /* no more data to transfer */
                DPRINTK("ata%u: dev %u command complete, drv_stat 0x%x\n",
                        ap->id, qc->dev->devno, status);

                WARN_ON(qc->err_mask);

                ap->hsm_task_state = HSM_ST_IDLE;

                /* complete taskfile transaction */
                ata_hsm_qc_complete(qc, in_wq);

                poll_next = 0;
                break;

        case HSM_ST_ERR:
                /* make sure qc->err_mask is available to
                 * know what's wrong and recover
                 */
                WARN_ON(qc->err_mask == 0);

                ap->hsm_task_state = HSM_ST_IDLE;

                /* complete taskfile transaction */
                ata_hsm_qc_complete(qc, in_wq);

                poll_next = 0;
                break;
        default:
                poll_next = 0;
                BUG();
        }

        return poll_next;
}

static void ata_pio_task(void *_data)
{
        struct ata_queued_cmd *qc = _data;
        struct ata_port *ap = qc->ap;
        u8 status;
        int poll_next;

fsm_start:
        WARN_ON(ap->hsm_task_state == HSM_ST_IDLE);

        /*
         * This is purely heuristic.  This is a fast path.
         * Sometimes when we enter, BSY will be cleared in
         * a chk-status or two.  If not, the drive is probably seeking
         * or something.  Snooze for a couple msecs, then
         * chk-status again.  If still busy, queue delayed work.
         */
        status = ata_busy_wait(ap, ATA_BUSY, 5);
        if (status & ATA_BUSY) {
                msleep(2);
                status = ata_busy_wait(ap, ATA_BUSY, 10);
                if (status & ATA_BUSY) {
                        ata_port_queue_task(ap, ata_pio_task, qc, ATA_SHORT_PAUSE);
                        return;
                }
        }

        /* move the HSM */
        poll_next = ata_hsm_move(ap, qc, status, 1);

        /* another command or interrupt handler
         * may be running at this point.
         */
        if (poll_next)
                goto fsm_start;
}

/**
 *      ata_qc_new - Request an available ATA command, for queueing
 *      @ap: Port associated with device @dev
 *      @dev: Device from whom we request an available command structure
 *
 *      LOCKING:
 *      None.
 */

static struct ata_queued_cmd *ata_qc_new(struct ata_port *ap)
{
        struct ata_queued_cmd *qc = NULL;
        unsigned int i;

        /* no command while frozen */
        if (unlikely(ap->flags & ATA_FLAG_FROZEN))
                return NULL;

        /* the last tag is reserved for internal command. */
        for (i = 0; i < ATA_MAX_QUEUE - 1; i++)
                if (!test_and_set_bit(i, &ap->qc_allocated)) {
                        qc = __ata_qc_from_tag(ap, i);
                        break;
                }

        if (qc)
                qc->tag = i;

        return qc;
}

/**
 *      ata_qc_new_init - Request an available ATA command, and initialize it
 *      @dev: Device from whom we request an available command structure
 *
 *      LOCKING:
 *      None.
 */

struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev)
{
        struct ata_port *ap = dev->ap;
        struct ata_queued_cmd *qc;

        qc = ata_qc_new(ap);
        if (qc) {
                qc->scsicmd = NULL;
                qc->ap = ap;
                qc->dev = dev;

                ata_qc_reinit(qc);
        }

        return qc;
}

/**
 *      ata_qc_free - free unused ata_queued_cmd
 *      @qc: Command to complete
 *
 *      Designed to free unused ata_queued_cmd object
 *      in case something prevents using it.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_qc_free(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        unsigned int tag;

        WARN_ON(qc == NULL);    /* ata_qc_from_tag _might_ return NULL */

        qc->flags = 0;
        tag = qc->tag;
        if (likely(ata_tag_valid(tag))) {
                qc->tag = ATA_TAG_POISON;
                clear_bit(tag, &ap->qc_allocated);
        }
}

void __ata_qc_complete(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

        WARN_ON(qc == NULL);    /* ata_qc_from_tag _might_ return NULL */
        WARN_ON(!(qc->flags & ATA_QCFLAG_ACTIVE));

        if (likely(qc->flags & ATA_QCFLAG_DMAMAP))
                ata_sg_clean(qc);

        /* command should be marked inactive atomically with qc completion */
        if (qc->tf.protocol == ATA_PROT_NCQ)
                ap->sactive &= ~(1 << qc->tag);
        else
                ap->active_tag = ATA_TAG_POISON;

        /* atapi: mark qc as inactive to prevent the interrupt handler
         * from completing the command twice later, before the error handler
         * is called. (when rc != 0 and atapi request sense is needed)
         */
        qc->flags &= ~ATA_QCFLAG_ACTIVE;
        ap->qc_active &= ~(1 << qc->tag);

        /* call completion callback */
        qc->complete_fn(qc);
}

/**
 *      ata_qc_complete - Complete an active ATA command
 *      @qc: Command to complete
 *      @err_mask: ATA Status register contents
 *
 *      Indicate to the mid and upper layers that an ATA
 *      command has completed, with either an ok or not-ok status.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_qc_complete(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

        /* XXX: New EH and old EH use different mechanisms to
         * synchronize EH with regular execution path.
         *
         * In new EH, a failed qc is marked with ATA_QCFLAG_FAILED.
         * Normal execution path is responsible for not accessing a
         * failed qc.  libata core enforces the rule by returning NULL
         * from ata_qc_from_tag() for failed qcs.
         *
         * Old EH depends on ata_qc_complete() nullifying completion
         * requests if ATA_QCFLAG_EH_SCHEDULED is set.  Old EH does
         * not synchronize with interrupt handler.  Only PIO task is
         * taken care of.
         */
        if (ap->ops->error_handler) {
                WARN_ON(ap->flags & ATA_FLAG_FROZEN);

                if (unlikely(qc->err_mask))
                        qc->flags |= ATA_QCFLAG_FAILED;

                if (unlikely(qc->flags & ATA_QCFLAG_FAILED)) {
                        if (!ata_tag_internal(qc->tag)) {
                                /* always fill result TF for failed qc */
                                ap->ops->tf_read(ap, &qc->result_tf);
                                ata_qc_schedule_eh(qc);
                                return;
                        }
                }

                /* read result TF if requested */
                if (qc->flags & ATA_QCFLAG_RESULT_TF)
                        ap->ops->tf_read(ap, &qc->result_tf);

                __ata_qc_complete(qc);
        } else {
                if (qc->flags & ATA_QCFLAG_EH_SCHEDULED)
                        return;

                /* read result TF if failed or requested */
                if (qc->err_mask || qc->flags & ATA_QCFLAG_RESULT_TF)
                        ap->ops->tf_read(ap, &qc->result_tf);

                __ata_qc_complete(qc);
        }
}

/**
 *      ata_qc_complete_multiple - Complete multiple qcs successfully
 *      @ap: port in question
 *      @qc_active: new qc_active mask
 *      @finish_qc: LLDD callback invoked before completing a qc
 *
 *      Complete in-flight commands.  This functions is meant to be
 *      called from low-level driver's interrupt routine to complete
 *      requests normally.  ap->qc_active and @qc_active is compared
 *      and commands are completed accordingly.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Number of completed commands on success, -errno otherwise.
 */
int ata_qc_complete_multiple(struct ata_port *ap, u32 qc_active,
                             void (*finish_qc)(struct ata_queued_cmd *))
{
        int nr_done = 0;
        u32 done_mask;
        int i;

        done_mask = ap->qc_active ^ qc_active;

        if (unlikely(done_mask & qc_active)) {
                ata_port_printk(ap, KERN_ERR, "illegal qc_active transition "
                                "(%08x->%08x)\n", ap->qc_active, qc_active);
                return -EINVAL;
        }

        for (i = 0; i < ATA_MAX_QUEUE; i++) {
                struct ata_queued_cmd *qc;

                if (!(done_mask & (1 << i)))
                        continue;

                if ((qc = ata_qc_from_tag(ap, i))) {
                        if (finish_qc)
                                finish_qc(qc);
                        ata_qc_complete(qc);
                        nr_done++;
                }
        }

        return nr_done;
}

static inline int ata_should_dma_map(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

        switch (qc->tf.protocol) {
        case ATA_PROT_NCQ:
        case ATA_PROT_DMA:
        case ATA_PROT_ATAPI_DMA:
                return 1;

        case ATA_PROT_ATAPI:
        case ATA_PROT_PIO:
                if (ap->flags & ATA_FLAG_PIO_DMA)
                        return 1;

                /* fall through */

        default:
                return 0;
        }

        /* never reached */
}

/**
 *      ata_qc_issue - issue taskfile to device
 *      @qc: command to issue to device
 *
 *      Prepare an ATA command to submission to device.
 *      This includes mapping the data into a DMA-able
 *      area, filling in the S/G table, and finally
 *      writing the taskfile to hardware, starting the command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_qc_issue(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

        /* Make sure only one non-NCQ command is outstanding.  The
         * check is skipped for old EH because it reuses active qc to
         * request ATAPI sense.
         */
        WARN_ON(ap->ops->error_handler && ata_tag_valid(ap->active_tag));

        if (qc->tf.protocol == ATA_PROT_NCQ) {
                WARN_ON(ap->sactive & (1 << qc->tag));
                ap->sactive |= 1 << qc->tag;
        } else {
                WARN_ON(ap->sactive);
                ap->active_tag = qc->tag;
        }

        qc->flags |= ATA_QCFLAG_ACTIVE;
        ap->qc_active |= 1 << qc->tag;

        if (ata_should_dma_map(qc)) {
                if (qc->flags & ATA_QCFLAG_SG) {
                        if (ata_sg_setup(qc))
                                goto sg_err;
                } else if (qc->flags & ATA_QCFLAG_SINGLE) {
                        if (ata_sg_setup_one(qc))
                                goto sg_err;
                }
        } else {
                qc->flags &= ~ATA_QCFLAG_DMAMAP;
        }

        ap->ops->qc_prep(qc);

        qc->err_mask |= ap->ops->qc_issue(qc);
        if (unlikely(qc->err_mask))
                goto err;
        return;

sg_err:
        qc->flags &= ~ATA_QCFLAG_DMAMAP;
        qc->err_mask |= AC_ERR_SYSTEM;
err:
        ata_qc_complete(qc);
}

/**
 *      ata_qc_issue_prot - issue taskfile to device in proto-dependent manner
 *      @qc: command to issue to device
 *
 *      Using various libata functions and hooks, this function
 *      starts an ATA command.  ATA commands are grouped into
 *      classes called "protocols", and issuing each type of protocol
 *      is slightly different.
 *
 *      May be used as the qc_issue() entry in ata_port_operations.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, AC_ERR_* mask on failure
 */

unsigned int ata_qc_issue_prot(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

        /* Use polling pio if the LLD doesn't handle
         * interrupt driven pio and atapi CDB interrupt.
         */
        if (ap->flags & ATA_FLAG_PIO_POLLING) {
                switch (qc->tf.protocol) {
                case ATA_PROT_PIO:
                case ATA_PROT_ATAPI:
                case ATA_PROT_ATAPI_NODATA:
                        qc->tf.flags |= ATA_TFLAG_POLLING;
                        break;
                case ATA_PROT_ATAPI_DMA:
                        if (qc->dev->flags & ATA_DFLAG_CDB_INTR)
                                /* see ata_dma_blacklisted() */
                                BUG();
                        break;
                default:
                        break;
                }
        }

        /* select the device */
        ata_dev_select(ap, qc->dev->devno, 1, 0);

        /* start the command */
        switch (qc->tf.protocol) {
        case ATA_PROT_NODATA:
                if (qc->tf.flags & ATA_TFLAG_POLLING)
                        ata_qc_set_polling(qc);

                ata_tf_to_host(ap, &qc->tf);
                ap->hsm_task_state = HSM_ST_LAST;

                if (qc->tf.flags & ATA_TFLAG_POLLING)
                        ata_port_queue_task(ap, ata_pio_task, qc, 0);

                break;

        case ATA_PROT_DMA:
                WARN_ON(qc->tf.flags & ATA_TFLAG_POLLING);

                ap->ops->tf_load(ap, &qc->tf);   /* load tf registers */
                ap->ops->bmdma_setup(qc);           /* set up bmdma */
                ap->ops->bmdma_start(qc);           /* initiate bmdma */
                ap->hsm_task_state = HSM_ST_LAST;
                break;

        case ATA_PROT_PIO:
                if (qc->tf.flags & ATA_TFLAG_POLLING)
                        ata_qc_set_polling(qc);

                ata_tf_to_host(ap, &qc->tf);

                if (qc->tf.flags & ATA_TFLAG_WRITE) {
                        /* PIO data out protocol */
                        ap->hsm_task_state = HSM_ST_FIRST;
                        ata_port_queue_task(ap, ata_pio_task, qc, 0);

                        /* always send first data block using
                         * the ata_pio_task() codepath.
                         */
                } else {
                        /* PIO data in protocol */
                        ap->hsm_task_state = HSM_ST;

                        if (qc->tf.flags & ATA_TFLAG_POLLING)
                                ata_port_queue_task(ap, ata_pio_task, qc, 0);

                        /* if polling, ata_pio_task() handles the rest.
                         * otherwise, interrupt handler takes over from here.
                         */
                }

                break;

        case ATA_PROT_ATAPI:
        case ATA_PROT_ATAPI_NODATA:
                if (qc->tf.flags & ATA_TFLAG_POLLING)
                        ata_qc_set_polling(qc);

                ata_tf_to_host(ap, &qc->tf);

                ap->hsm_task_state = HSM_ST_FIRST;

                /* send cdb by polling if no cdb interrupt */
                if ((!(qc->dev->flags & ATA_DFLAG_CDB_INTR)) ||
                    (qc->tf.flags & ATA_TFLAG_POLLING))
                        ata_port_queue_task(ap, ata_pio_task, qc, 0);
                break;

        case ATA_PROT_ATAPI_DMA:
                WARN_ON(qc->tf.flags & ATA_TFLAG_POLLING);

                ap->ops->tf_load(ap, &qc->tf);   /* load tf registers */
                ap->ops->bmdma_setup(qc);           /* set up bmdma */
                ap->hsm_task_state = HSM_ST_FIRST;

                /* send cdb by polling if no cdb interrupt */
                if (!(qc->dev->flags & ATA_DFLAG_CDB_INTR))
                        ata_port_queue_task(ap, ata_pio_task, qc, 0);
                break;

        default:
                WARN_ON(1);
                return AC_ERR_SYSTEM;
        }

        return 0;
}

/**
 *      ata_host_intr - Handle host interrupt for given (port, task)
 *      @ap: Port on which interrupt arrived (possibly...)
 *      @qc: Taskfile currently active in engine
 *
 *      Handle host interrupt for given queued command.  Currently,
 *      only DMA interrupts are handled.  All other commands are
 *      handled via polling with interrupts disabled (nIEN bit).
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      One if interrupt was handled, zero if not (shared irq).
 */

inline unsigned int ata_host_intr (struct ata_port *ap,
                                   struct ata_queued_cmd *qc)
{
        u8 status, host_stat = 0;

        VPRINTK("ata%u: protocol %d task_state %d\n",
                ap->id, qc->tf.protocol, ap->hsm_task_state);

        /* Check whether we are expecting interrupt in this state */
        switch (ap->hsm_task_state) {
        case HSM_ST_FIRST:
                /* Some pre-ATAPI-4 devices assert INTRQ
                 * at this state when ready to receive CDB.
                 */

                /* Check the ATA_DFLAG_CDB_INTR flag is enough here.
                 * The flag was turned on only for atapi devices.
                 * No need to check is_atapi_taskfile(&qc->tf) again.
                 */
                if (!(qc->dev->flags & ATA_DFLAG_CDB_INTR))
                        goto idle_irq;
                break;
        case HSM_ST_LAST:
                if (qc->tf.protocol == ATA_PROT_DMA ||
                    qc->tf.protocol == ATA_PROT_ATAPI_DMA) {
                        /* check status of DMA engine */
                        host_stat = ap->ops->bmdma_status(ap);
                        VPRINTK("ata%u: host_stat 0x%X\n", ap->id, host_stat);

                        /* if it's not our irq... */
                        if (!(host_stat & ATA_DMA_INTR))
                                goto idle_irq;

                        /* before we do anything else, clear DMA-Start bit */
                        ap->ops->bmdma_stop(qc);

                        if (unlikely(host_stat & ATA_DMA_ERR)) {
                                /* error when transfering data to/from memory */
                                qc->err_mask |= AC_ERR_HOST_BUS;
                                ap->hsm_task_state = HSM_ST_ERR;
                        }
                }
                break;
        case HSM_ST:
                break;
        default:
                goto idle_irq;
        }

        /* check altstatus */
        status = ata_altstatus(ap);
        if (status & ATA_BUSY)
                goto idle_irq;

        /* check main status, clearing INTRQ */
        status = ata_chk_status(ap);
        if (unlikely(status & ATA_BUSY))
                goto idle_irq;

        /* ack bmdma irq events */
        ap->ops->irq_clear(ap);

        ata_hsm_move(ap, qc, status, 0);
        return 1;       /* irq handled */

idle_irq:
        ap->stats.idle_irq++;

#ifdef ATA_IRQ_TRAP
        if ((ap->stats.idle_irq % 1000) == 0) {
                ata_irq_ack(ap, 0); /* debug trap */
                ata_port_printk(ap, KERN_WARNING, "irq trap\n");
                return 1;
        }
#endif
        return 0;       /* irq not handled */
}

/**
 *      ata_interrupt - Default ATA host interrupt handler
 *      @irq: irq line (unused)
 *      @dev_instance: pointer to our ata_host_set information structure
 *      @regs: unused
 *
 *      Default interrupt handler for PCI IDE devices.  Calls
 *      ata_host_intr() for each port that is not disabled.
 *
 *      LOCKING:
 *      Obtains host_set lock during operation.
 *
 *      RETURNS:
 *      IRQ_NONE or IRQ_HANDLED.
 */

irqreturn_t ata_interrupt (int irq, void *dev_instance, struct pt_regs *regs)
{
        struct ata_host_set *host_set = dev_instance;
        unsigned int i;
        unsigned int handled = 0;
        unsigned long flags;

        /* TODO: make _irqsave conditional on x86 PCI IDE legacy mode */
        spin_lock_irqsave(&host_set->lock, flags);

        for (i = 0; i < host_set->n_ports; i++) {
                struct ata_port *ap;

                ap = host_set->ports[i];
                if (ap &&
                    !(ap->flags & ATA_FLAG_DISABLED)) {
                        struct ata_queued_cmd *qc;

                        qc = ata_qc_from_tag(ap, ap->active_tag);
                        if (qc && (!(qc->tf.flags & ATA_TFLAG_POLLING)) &&
                            (qc->flags & ATA_QCFLAG_ACTIVE))
                                handled |= ata_host_intr(ap, qc);
                }
        }

        spin_unlock_irqrestore(&host_set->lock, flags);

        return IRQ_RETVAL(handled);
}

/**
 *      sata_scr_valid - test whether SCRs are accessible
 *      @ap: ATA port to test SCR accessibility for
 *
 *      Test whether SCRs are accessible for @ap.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      1 if SCRs are accessible, 0 otherwise.
 */
int sata_scr_valid(struct ata_port *ap)
{
        return ap->cbl == ATA_CBL_SATA && ap->ops->scr_read;
}

/**
 *      sata_scr_read - read SCR register of the specified port
 *      @ap: ATA port to read SCR for
 *      @reg: SCR to read
 *      @val: Place to store read value
 *
 *      Read SCR register @reg of @ap into *@val.  This function is
 *      guaranteed to succeed if the cable type of the port is SATA
 *      and the port implements ->scr_read.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      0 on success, negative errno on failure.
 */
int sata_scr_read(struct ata_port *ap, int reg, u32 *val)
{
        if (sata_scr_valid(ap)) {
                *val = ap->ops->scr_read(ap, reg);
                return 0;
        }
        return -EOPNOTSUPP;
}

/**
 *      sata_scr_write - write SCR register of the specified port
 *      @ap: ATA port to write SCR for
 *      @reg: SCR to write
 *      @val: value to write
 *
 *      Write @val to SCR register @reg of @ap.  This function is
 *      guaranteed to succeed if the cable type of the port is SATA
 *      and the port implements ->scr_read.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      0 on success, negative errno on failure.
 */
int sata_scr_write(struct ata_port *ap, int reg, u32 val)
{
        if (sata_scr_valid(ap)) {
                ap->ops->scr_write(ap, reg, val);
                return 0;
        }
        return -EOPNOTSUPP;
}

/**
 *      sata_scr_write_flush - write SCR register of the specified port and flush
 *      @ap: ATA port to write SCR for
 *      @reg: SCR to write
 *      @val: value to write
 *
 *      This function is identical to sata_scr_write() except that this
 *      function performs flush after writing to the register.
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      0 on success, negative errno on failure.
 */
int sata_scr_write_flush(struct ata_port *ap, int reg, u32 val)
{
        if (sata_scr_valid(ap)) {
                ap->ops->scr_write(ap, reg, val);
                ap->ops->scr_read(ap, reg);
                return 0;
        }
        return -EOPNOTSUPP;
}

/**
 *      ata_port_online - test whether the given port is online
 *      @ap: ATA port to test
 *
 *      Test whether @ap is online.  Note that this function returns 0
 *      if online status of @ap cannot be obtained, so
 *      ata_port_online(ap) != !ata_port_offline(ap).
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      1 if the port online status is available and online.
 */
int ata_port_online(struct ata_port *ap)
{
        u32 sstatus;

        if (!sata_scr_read(ap, SCR_STATUS, &sstatus) && (sstatus & 0xf) == 0x3)
                return 1;
        return 0;
}

/**
 *      ata_port_offline - test whether the given port is offline
 *      @ap: ATA port to test
 *
 *      Test whether @ap is offline.  Note that this function returns
 *      0 if offline status of @ap cannot be obtained, so
 *      ata_port_online(ap) != !ata_port_offline(ap).
 *
 *      LOCKING:
 *      None.
 *
 *      RETURNS:
 *      1 if the port offline status is available and offline.
 */
int ata_port_offline(struct ata_port *ap)
{
        u32 sstatus;

        if (!sata_scr_read(ap, SCR_STATUS, &sstatus) && (sstatus & 0xf) != 0x3)
                return 1;
        return 0;
}

int ata_flush_cache(struct ata_device *dev)
{
        unsigned int err_mask;
        u8 cmd;

        if (!ata_try_flush_cache(dev))
                return 0;

        if (ata_id_has_flush_ext(dev->id))
                cmd = ATA_CMD_FLUSH_EXT;
        else
                cmd = ATA_CMD_FLUSH;

        err_mask = ata_do_simple_cmd(dev, cmd);
        if (err_mask) {
                ata_dev_printk(dev, KERN_ERR, "failed to flush cache\n");
                return -EIO;
        }

        return 0;
}

static int ata_standby_drive(struct ata_device *dev)
{
        unsigned int err_mask;

        err_mask = ata_do_simple_cmd(dev, ATA_CMD_STANDBYNOW1);
        if (err_mask) {
                ata_dev_printk(dev, KERN_ERR, "failed to standby drive "
                               "(err_mask=0x%x)\n", err_mask);
                return -EIO;
        }

        return 0;
}

static int ata_start_drive(struct ata_device *dev)
{
        unsigned int err_mask;

        err_mask = ata_do_simple_cmd(dev, ATA_CMD_IDLEIMMEDIATE);
        if (err_mask) {
                ata_dev_printk(dev, KERN_ERR, "failed to start drive "
                               "(err_mask=0x%x)\n", err_mask);
                return -EIO;
        }

        return 0;
}

/**
 *      ata_device_resume - wakeup a previously suspended devices
 *      @dev: the device to resume
 *
 *      Kick the drive back into action, by sending it an idle immediate
 *      command and making sure its transfer mode matches between drive
 *      and host.
 *
 */
int ata_device_resume(struct ata_device *dev)
{
        struct ata_port *ap = dev->ap;

        if (ap->flags & ATA_FLAG_SUSPENDED) {
                struct ata_device *failed_dev;

                ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);
                ata_busy_wait(ap, ATA_BUSY | ATA_DRQ, 200000);

                ap->flags &= ~ATA_FLAG_SUSPENDED;
                while (ata_set_mode(ap, &failed_dev))
                        ata_dev_disable(failed_dev);
        }
        if (!ata_dev_enabled(dev))
                return 0;
        if (dev->class == ATA_DEV_ATA)
                ata_start_drive(dev);

        return 0;
}

/**
 *      ata_device_suspend - prepare a device for suspend
 *      @dev: the device to suspend
 *      @state: target power management state
 *
 *      Flush the cache on the drive, if appropriate, then issue a
 *      standbynow command.
 */
int ata_device_suspend(struct ata_device *dev, pm_message_t state)
{
        struct ata_port *ap = dev->ap;

        if (!ata_dev_enabled(dev))
                return 0;
        if (dev->class == ATA_DEV_ATA)
                ata_flush_cache(dev);

        if (state.event != PM_EVENT_FREEZE)
                ata_standby_drive(dev);
        ap->flags |= ATA_FLAG_SUSPENDED;
        return 0;
}

/**
 *      ata_port_start - Set port up for dma.
 *      @ap: Port to initialize
 *
 *      Called just after data structures for each port are
 *      initialized.  Allocates space for PRD table.
 *
 *      May be used as the port_start() entry in ata_port_operations.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

int ata_port_start (struct ata_port *ap)
{
        struct device *dev = ap->dev;
        int rc;

        ap->prd = dma_alloc_coherent(dev, ATA_PRD_TBL_SZ, &ap->prd_dma, GFP_KERNEL);
        if (!ap->prd)
                return -ENOMEM;

        rc = ata_pad_alloc(ap, dev);
        if (rc) {
                dma_free_coherent(dev, ATA_PRD_TBL_SZ, ap->prd, ap->prd_dma);
                return rc;
        }

        DPRINTK("prd alloc, virt %p, dma %llx\n", ap->prd, (unsigned long long) ap->prd_dma);

        return 0;
}


/**
 *      ata_port_stop - Undo ata_port_start()
 *      @ap: Port to shut down
 *
 *      Frees the PRD table.
 *
 *      May be used as the port_stop() entry in ata_port_operations.
 *
 *      LOCKING:
 *      Inherited from caller.
 */

void ata_port_stop (struct ata_port *ap)
{
        struct device *dev = ap->dev;

        dma_free_coherent(dev, ATA_PRD_TBL_SZ, ap->prd, ap->prd_dma);
        ata_pad_free(ap, dev);
}

void ata_host_stop (struct ata_host_set *host_set)
{
        if (host_set->mmio_base)
                iounmap(host_set->mmio_base);
}


/**
 *      ata_host_remove - Unregister SCSI host structure with upper layers
 *      @ap: Port to unregister
 *      @do_unregister: 1 if we fully unregister, 0 to just stop the port
 *
 *      LOCKING:
 *      Inherited from caller.
 */

static void ata_host_remove(struct ata_port *ap, unsigned int do_unregister)
{
        struct Scsi_Host *sh = ap->host;

        DPRINTK("ENTER\n");

        if (do_unregister)
                scsi_remove_host(sh);

        ap->ops->port_stop(ap);
}

/**
 *      ata_dev_init - Initialize an ata_device structure
 *      @dev: Device structure to initialize
 *
 *      Initialize @dev in preparation for probing.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
void ata_dev_init(struct ata_device *dev)
{
        struct ata_port *ap = dev->ap;
        unsigned long flags;

        /* SATA spd limit is bound to the first device */
        ap->sata_spd_limit = ap->hw_sata_spd_limit;

        /* High bits of dev->flags are used to record warm plug
         * requests which occur asynchronously.  Synchronize using
         * host_set lock.
         */
        spin_lock_irqsave(ap->lock, flags);
        dev->flags &= ~ATA_DFLAG_INIT_MASK;
        spin_unlock_irqrestore(ap->lock, flags);

        memset((void *)dev + ATA_DEVICE_CLEAR_OFFSET, 0,
               sizeof(*dev) - ATA_DEVICE_CLEAR_OFFSET);
        dev->pio_mask = UINT_MAX;
        dev->mwdma_mask = UINT_MAX;
        dev->udma_mask = UINT_MAX;
}

/**
 *      ata_host_init - Initialize an ata_port structure
 *      @ap: Structure to initialize
 *      @host: associated SCSI mid-layer structure
 *      @host_set: Collection of hosts to which @ap belongs
 *      @ent: Probe information provided by low-level driver
 *      @port_no: Port number associated with this ata_port
 *
 *      Initialize a new ata_port structure, and its associated
 *      scsi_host.
 *
 *      LOCKING:
 *      Inherited from caller.
 */
static void ata_host_init(struct ata_port *ap, struct Scsi_Host *host,
                          struct ata_host_set *host_set,
                          const struct ata_probe_ent *ent, unsigned int port_no)
{
        unsigned int i;

        host->max_id = 16;
        host->max_lun = 1;
        host->max_channel = 1;
        host->unique_id = ata_unique_id++;
        host->max_cmd_len = 12;

        ap->lock = &host_set->lock;
        ap->flags = ATA_FLAG_DISABLED;
        ap->id = host->unique_id;
        ap->host = host;
        ap->ctl = ATA_DEVCTL_OBS;
        ap->host_set = host_set;
        ap->dev = ent->dev;
        ap->port_no = port_no;
        ap->hard_port_no =
                ent->legacy_mode ? ent->hard_port_no : port_no;
        ap->pio_mask = ent->pio_mask;
        ap->mwdma_mask = ent->mwdma_mask;
        ap->udma_mask = ent->udma_mask;
        ap->flags |= ent->host_flags;
        ap->ops = ent->port_ops;
        ap->hw_sata_spd_limit = UINT_MAX;
        ap->active_tag = ATA_TAG_POISON;
        ap->last_ctl = 0xFF;

#if defined(ATA_VERBOSE_DEBUG)
        /* turn on all debugging levels */
        ap->msg_enable = 0x00FF;
#elif defined(ATA_DEBUG)
        ap->msg_enable = ATA_MSG_DRV | ATA_MSG_INFO | ATA_MSG_CTL | ATA_MSG_WARN | ATA_MSG_ERR;
#else
        ap->msg_enable = ATA_MSG_DRV | ATA_MSG_ERR | ATA_MSG_WARN;
#endif

        INIT_WORK(&ap->port_task, NULL, NULL);
        INIT_WORK(&ap->hotplug_task, ata_scsi_hotplug, ap);
        INIT_WORK(&ap->scsi_rescan_task, ata_scsi_dev_rescan, ap);
        INIT_LIST_HEAD(&ap->eh_done_q);
        init_waitqueue_head(&ap->eh_wait_q);

        /* set cable type */
        ap->cbl = ATA_CBL_NONE;
        if (ap->flags & ATA_FLAG_SATA)
                ap->cbl = ATA_CBL_SATA;

        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *dev = &ap->device[i];
                dev->ap = ap;
                dev->devno = i;
                ata_dev_init(dev);
        }

#ifdef ATA_IRQ_TRAP
        ap->stats.unhandled_irq = 1;
        ap->stats.idle_irq = 1;
#endif

        memcpy(&ap->ioaddr, &ent->port[port_no], sizeof(struct ata_ioports));
}

/**
 *      ata_host_add - Attach low-level ATA driver to system
 *      @ent: Information provided by low-level driver
 *      @host_set: Collections of ports to which we add
 *      @port_no: Port number associated with this host
 *
 *      Attach low-level ATA driver to system.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 *      RETURNS:
 *      New ata_port on success, for NULL on error.
 */

static struct ata_port * ata_host_add(const struct ata_probe_ent *ent,
                                      struct ata_host_set *host_set,
                                      unsigned int port_no)
{
        struct Scsi_Host *host;
        struct ata_port *ap;
        int rc;

        DPRINTK("ENTER\n");

        if (!ent->port_ops->error_handler &&
            !(ent->host_flags & (ATA_FLAG_SATA_RESET | ATA_FLAG_SRST))) {
                printk(KERN_ERR "ata%u: no reset mechanism available\n",
                       port_no);
                return NULL;
        }

        host = scsi_host_alloc(ent->sht, sizeof(struct ata_port));
        if (!host)
                return NULL;

        host->transportt = &ata_scsi_transport_template;

        ap = ata_shost_to_port(host);

        ata_host_init(ap, host, host_set, ent, port_no);

        rc = ap->ops->port_start(ap);
        if (rc)
                goto err_out;

        return ap;

err_out:
        scsi_host_put(host);
        return NULL;
}

/**
 *      ata_device_add - Register hardware device with ATA and SCSI layers
 *      @ent: Probe information describing hardware device to be registered
 *
 *      This function processes the information provided in the probe
 *      information struct @ent, allocates the necessary ATA and SCSI
 *      host information structures, initializes them, and registers
 *      everything with requisite kernel subsystems.
 *
 *      This function requests irqs, probes the ATA bus, and probes
 *      the SCSI bus.
 *
 *      LOCKING:
 *      PCI/etc. bus probe sem.
 *
 *      RETURNS:
 *      Number of ports registered.  Zero on error (no ports registered).
 */
int ata_device_add(const struct ata_probe_ent *ent)
{
        unsigned int count = 0, i;
        struct device *dev = ent->dev;
        struct ata_host_set *host_set;
        int rc;

        DPRINTK("ENTER\n");
        /* alloc a container for our list of ATA ports (buses) */
        host_set = kzalloc(sizeof(struct ata_host_set) +
                           (ent->n_ports * sizeof(void *)), GFP_KERNEL);
        if (!host_set)
                return 0;
        spin_lock_init(&host_set->lock);

        host_set->dev = dev;
        host_set->n_ports = ent->n_ports;
        host_set->irq = ent->irq;
        host_set->mmio_base = ent->mmio_base;
        host_set->private_data = ent->private_data;
        host_set->ops = ent->port_ops;
        host_set->flags = ent->host_set_flags;

        /* register each port bound to this device */
        for (i = 0; i < ent->n_ports; i++) {
                struct ata_port *ap;
                unsigned long xfer_mode_mask;

                ap = ata_host_add(ent, host_set, i);
                if (!ap)
                        goto err_out;

                host_set->ports[i] = ap;
                xfer_mode_mask =(ap->udma_mask << ATA_SHIFT_UDMA) |
                                (ap->mwdma_mask << ATA_SHIFT_MWDMA) |
                                (ap->pio_mask << ATA_SHIFT_PIO);

                /* print per-port info to dmesg */
                ata_port_printk(ap, KERN_INFO, "%cATA max %s cmd 0x%lX "
                                "ctl 0x%lX bmdma 0x%lX irq %lu\n",
                                ap->flags & ATA_FLAG_SATA ? 'S' : 'P',
                                ata_mode_string(xfer_mode_mask),
                                ap->ioaddr.cmd_addr,
                                ap->ioaddr.ctl_addr,
                                ap->ioaddr.bmdma_addr,
                                ent->irq);

                ata_chk_status(ap);
                host_set->ops->irq_clear(ap);
                ata_eh_freeze_port(ap); /* freeze port before requesting IRQ */
                count++;
        }

        if (!count)
                goto err_free_ret;

        /* obtain irq, that is shared between channels */
        rc = request_irq(ent->irq, ent->port_ops->irq_handler, ent->irq_flags,
                         DRV_NAME, host_set);
        if (rc) {
                dev_printk(KERN_ERR, dev, "irq %lu request failed: %d\n",
                           ent->irq, rc);
                goto err_out;
        }

        /* perform each probe synchronously */
        DPRINTK("probe begin\n");
        for (i = 0; i < count; i++) {
                struct ata_port *ap;
                u32 scontrol;
                int rc;

                ap = host_set->ports[i];

                /* init sata_spd_limit to the current value */
                if (sata_scr_read(ap, SCR_CONTROL, &scontrol) == 0) {
                        int spd = (scontrol >> 4) & 0xf;
                        ap->hw_sata_spd_limit &= (1 << spd) - 1;
                }
                ap->sata_spd_limit = ap->hw_sata_spd_limit;

                rc = scsi_add_host(ap->host, dev);
                if (rc) {
                        ata_port_printk(ap, KERN_ERR, "scsi_add_host failed\n");
                        /* FIXME: do something useful here */
                        /* FIXME: handle unconditional calls to
                         * scsi_scan_host and ata_host_remove, below,
                         * at the very least
                         */
                }

                if (ap->ops->error_handler) {
                        unsigned long flags;

                        ata_port_probe(ap);

                        /* kick EH for boot probing */
                        spin_lock_irqsave(ap->lock, flags);

                        ap->eh_info.probe_mask = (1 << ATA_MAX_DEVICES) - 1;
                        ap->eh_info.action |= ATA_EH_SOFTRESET;

                        ap->flags |= ATA_FLAG_LOADING;
                        ata_port_schedule_eh(ap);

                        spin_unlock_irqrestore(ap->lock, flags);

                        /* wait for EH to finish */
                        ata_port_wait_eh(ap);
                } else {
                        DPRINTK("ata%u: bus probe begin\n", ap->id);
                        rc = ata_bus_probe(ap);
                        DPRINTK("ata%u: bus probe end\n", ap->id);

                        if (rc) {
                                /* FIXME: do something useful here?
                                 * Current libata behavior will
                                 * tear down everything when
                                 * the module is removed
                                 * or the h/w is unplugged.
                                 */
                        }
                }
        }

        /* probes are done, now scan each port's disk(s) */
        DPRINTK("host probe begin\n");
        for (i = 0; i < count; i++) {
                struct ata_port *ap = host_set->ports[i];

                ata_scsi_scan_host(ap);
        }

        dev_set_drvdata(dev, host_set);

        VPRINTK("EXIT, returning %u\n", ent->n_ports);
        return ent->n_ports; /* success */

err_out:
        for (i = 0; i < count; i++) {
                ata_host_remove(host_set->ports[i], 1);
                scsi_host_put(host_set->ports[i]->host);
        }
err_free_ret:
        kfree(host_set);
        VPRINTK("EXIT, returning 0\n");
        return 0;
}

/**
 *      ata_port_detach - Detach ATA port in prepration of device removal
 *      @ap: ATA port to be detached
 *
 *      Detach all ATA devices and the associated SCSI devices of @ap;
 *      then, remove the associated SCSI host.  @ap is guaranteed to
 *      be quiescent on return from this function.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 */
void ata_port_detach(struct ata_port *ap)
{
        unsigned long flags;
        int i;

        if (!ap->ops->error_handler)
                return;

        /* tell EH we're leaving & flush EH */
        spin_lock_irqsave(ap->lock, flags);
        ap->flags |= ATA_FLAG_UNLOADING;
        spin_unlock_irqrestore(ap->lock, flags);

        ata_port_wait_eh(ap);

        /* EH is now guaranteed to see UNLOADING, so no new device
         * will be attached.  Disable all existing devices.
         */
        spin_lock_irqsave(ap->lock, flags);

        for (i = 0; i < ATA_MAX_DEVICES; i++)
                ata_dev_disable(&ap->device[i]);

        spin_unlock_irqrestore(ap->lock, flags);

        /* Final freeze & EH.  All in-flight commands are aborted.  EH
         * will be skipped and retrials will be terminated with bad
         * target.
         */
        spin_lock_irqsave(ap->lock, flags);
        ata_port_freeze(ap);    /* won't be thawed */
        spin_unlock_irqrestore(ap->lock, flags);

        ata_port_wait_eh(ap);

        /* Flush hotplug task.  The sequence is similar to
         * ata_port_flush_task().
         */
        flush_workqueue(ata_aux_wq);
        cancel_delayed_work(&ap->hotplug_task);
        flush_workqueue(ata_aux_wq);

        /* remove the associated SCSI host */
        scsi_remove_host(ap->host);
}

/**
 *      ata_host_set_remove - PCI layer callback for device removal
 *      @host_set: ATA host set that was removed
 *
 *      Unregister all objects associated with this host set. Free those
 *      objects.
 *
 *      LOCKING:
 *      Inherited from calling layer (may sleep).
 */

void ata_host_set_remove(struct ata_host_set *host_set)
{
        unsigned int i;

        for (i = 0; i < host_set->n_ports; i++)
                ata_port_detach(host_set->ports[i]);

        free_irq(host_set->irq, host_set);

        for (i = 0; i < host_set->n_ports; i++) {
                struct ata_port *ap = host_set->ports[i];

                ata_scsi_release(ap->host);

                if ((ap->flags & ATA_FLAG_NO_LEGACY) == 0) {
                        struct ata_ioports *ioaddr = &ap->ioaddr;

                        if (ioaddr->cmd_addr == 0x1f0)
                                release_region(0x1f0, 8);
                        else if (ioaddr->cmd_addr == 0x170)
                                release_region(0x170, 8);
                }

                scsi_host_put(ap->host);
        }

        if (host_set->ops->host_stop)
                host_set->ops->host_stop(host_set);

        kfree(host_set);
}

/**
 *      ata_scsi_release - SCSI layer callback hook for host unload
 *      @host: libata host to be unloaded
 *
 *      Performs all duties necessary to shut down a libata port...
 *      Kill port kthread, disable port, and release resources.
 *
 *      LOCKING:
 *      Inherited from SCSI layer.
 *
 *      RETURNS:
 *      One.
 */

int ata_scsi_release(struct Scsi_Host *host)
{
        struct ata_port *ap = ata_shost_to_port(host);

        DPRINTK("ENTER\n");

        ap->ops->port_disable(ap);
        ata_host_remove(ap, 0);

        DPRINTK("EXIT\n");
        return 1;
}

/**
 *      ata_std_ports - initialize ioaddr with standard port offsets.
 *      @ioaddr: IO address structure to be initialized
 *
 *      Utility function which initializes data_addr, error_addr,
 *      feature_addr, nsect_addr, lbal_addr, lbam_addr, lbah_addr,
 *      device_addr, status_addr, and command_addr to standard offsets
 *      relative to cmd_addr.
 *
 *      Does not set ctl_addr, altstatus_addr, bmdma_addr, or scr_addr.
 */

void ata_std_ports(struct ata_ioports *ioaddr)
{
        ioaddr->data_addr = ioaddr->cmd_addr + ATA_REG_DATA;
        ioaddr->error_addr = ioaddr->cmd_addr + ATA_REG_ERR;
        ioaddr->feature_addr = ioaddr->cmd_addr + ATA_REG_FEATURE;
        ioaddr->nsect_addr = ioaddr->cmd_addr + ATA_REG_NSECT;
        ioaddr->lbal_addr = ioaddr->cmd_addr + ATA_REG_LBAL;
        ioaddr->lbam_addr = ioaddr->cmd_addr + ATA_REG_LBAM;
        ioaddr->lbah_addr = ioaddr->cmd_addr + ATA_REG_LBAH;
        ioaddr->device_addr = ioaddr->cmd_addr + ATA_REG_DEVICE;
        ioaddr->status_addr = ioaddr->cmd_addr + ATA_REG_STATUS;
        ioaddr->command_addr = ioaddr->cmd_addr + ATA_REG_CMD;
}


#ifdef CONFIG_PCI

void ata_pci_host_stop (struct ata_host_set *host_set)
{
        struct pci_dev *pdev = to_pci_dev(host_set->dev);

        pci_iounmap(pdev, host_set->mmio_base);
}

/**
 *      ata_pci_remove_one - PCI layer callback for device removal
 *      @pdev: PCI device that was removed
 *
 *      PCI layer indicates to libata via this hook that
 *      hot-unplug or module unload event has occurred.
 *      Handle this by unregistering all objects associated
 *      with this PCI device.  Free those objects.  Then finally
 *      release PCI resources and disable device.
 *
 *      LOCKING:
 *      Inherited from PCI layer (may sleep).
 */

void ata_pci_remove_one (struct pci_dev *pdev)
{
        struct device *dev = pci_dev_to_dev(pdev);
        struct ata_host_set *host_set = dev_get_drvdata(dev);
        struct ata_host_set *host_set2 = host_set->next;

        ata_host_set_remove(host_set);
        if (host_set2)
                ata_host_set_remove(host_set2);

        pci_release_regions(pdev);
        pci_disable_device(pdev);
        dev_set_drvdata(dev, NULL);
}

/* move to PCI subsystem */
int pci_test_config_bits(struct pci_dev *pdev, const struct pci_bits *bits)
{
        unsigned long tmp = 0;

        switch (bits->width) {
        case 1: {
                u8 tmp8 = 0;
                pci_read_config_byte(pdev, bits->reg, &tmp8);
                tmp = tmp8;
                break;
        }
        case 2: {
                u16 tmp16 = 0;
                pci_read_config_word(pdev, bits->reg, &tmp16);
                tmp = tmp16;
                break;
        }
        case 4: {
                u32 tmp32 = 0;
                pci_read_config_dword(pdev, bits->reg, &tmp32);
                tmp = tmp32;
                break;
        }

        default:
                return -EINVAL;
        }

        tmp &= bits->mask;

        return (tmp == bits->val) ? 1 : 0;
}

int ata_pci_device_suspend(struct pci_dev *pdev, pm_message_t state)
{
        pci_save_state(pdev);
        pci_disable_device(pdev);
        pci_set_power_state(pdev, PCI_D3hot);
        return 0;
}

int ata_pci_device_resume(struct pci_dev *pdev)
{
        pci_set_power_state(pdev, PCI_D0);
        pci_restore_state(pdev);
        pci_enable_device(pdev);
        pci_set_master(pdev);
        return 0;
}
#endif /* CONFIG_PCI */


static int __init ata_init(void)
{
        ata_probe_timeout *= HZ;
        ata_wq = create_workqueue("ata");
        if (!ata_wq)
                return -ENOMEM;

        ata_aux_wq = create_singlethread_workqueue("ata_aux");
        if (!ata_aux_wq) {
                destroy_workqueue(ata_wq);
                return -ENOMEM;
        }

        printk(KERN_DEBUG "libata version " DRV_VERSION " loaded.\n");
        return 0;
}

static void __exit ata_exit(void)
{
        destroy_workqueue(ata_wq);
        destroy_workqueue(ata_aux_wq);
}

module_init(ata_init);
module_exit(ata_exit);

static unsigned long ratelimit_time;
static DEFINE_SPINLOCK(ata_ratelimit_lock);

int ata_ratelimit(void)
{
        int rc;
        unsigned long flags;

        spin_lock_irqsave(&ata_ratelimit_lock, flags);

        if (time_after(jiffies, ratelimit_time)) {
                rc = 1;
                ratelimit_time = jiffies + (HZ/5);
        } else
                rc = 0;

        spin_unlock_irqrestore(&ata_ratelimit_lock, flags);

        return rc;
}

/**
 *      ata_wait_register - wait until register value changes
 *      @reg: IO-mapped register
 *      @mask: Mask to apply to read register value
 *      @val: Wait condition
 *      @interval_msec: polling interval in milliseconds
 *      @timeout_msec: timeout in milliseconds
 *
 *      Waiting for some bits of register to change is a common
 *      operation for ATA controllers.  This function reads 32bit LE
 *      IO-mapped register @reg and tests for the following condition.
 *
 *      (*@reg & mask) != val
 *
 *      If the condition is met, it returns; otherwise, the process is
 *      repeated after @interval_msec until timeout.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep)
 *
 *      RETURNS:
 *      The final register value.
 */
u32 ata_wait_register(void __iomem *reg, u32 mask, u32 val,
                      unsigned long interval_msec,
                      unsigned long timeout_msec)
{
        unsigned long timeout;
        u32 tmp;

        tmp = ioread32(reg);

        /* Calculate timeout _after_ the first read to make sure
         * preceding writes reach the controller before starting to
         * eat away the timeout.
         */
        timeout = jiffies + (timeout_msec * HZ) / 1000;

        while ((tmp & mask) == val && time_before(jiffies, timeout)) {
                msleep(interval_msec);
                tmp = ioread32(reg);
        }

        return tmp;
}

/*
 * libata is essentially a library of internal helper functions for
 * low-level ATA host controller drivers.  As such, the API/ABI is
 * likely to change as new drivers are added and updated.
 * Do not depend on ABI/API stability.
 */

EXPORT_SYMBOL_GPL(sata_deb_timing_boot);
EXPORT_SYMBOL_GPL(sata_deb_timing_eh);
EXPORT_SYMBOL_GPL(sata_deb_timing_before_fsrst);
EXPORT_SYMBOL_GPL(ata_std_bios_param);
EXPORT_SYMBOL_GPL(ata_std_ports);
EXPORT_SYMBOL_GPL(ata_device_add);
EXPORT_SYMBOL_GPL(ata_port_detach);
EXPORT_SYMBOL_GPL(ata_host_set_remove);
EXPORT_SYMBOL_GPL(ata_sg_init);
EXPORT_SYMBOL_GPL(ata_sg_init_one);
EXPORT_SYMBOL_GPL(ata_hsm_move);
EXPORT_SYMBOL_GPL(ata_qc_complete);
EXPORT_SYMBOL_GPL(ata_qc_complete_multiple);
EXPORT_SYMBOL_GPL(ata_qc_issue_prot);
EXPORT_SYMBOL_GPL(ata_tf_load);
EXPORT_SYMBOL_GPL(ata_tf_read);
EXPORT_SYMBOL_GPL(ata_noop_dev_select);
EXPORT_SYMBOL_GPL(ata_std_dev_select);
EXPORT_SYMBOL_GPL(ata_tf_to_fis);
EXPORT_SYMBOL_GPL(ata_tf_from_fis);
EXPORT_SYMBOL_GPL(ata_check_status);
EXPORT_SYMBOL_GPL(ata_altstatus);
EXPORT_SYMBOL_GPL(ata_exec_command);
EXPORT_SYMBOL_GPL(ata_port_start);
EXPORT_SYMBOL_GPL(ata_port_stop);
EXPORT_SYMBOL_GPL(ata_host_stop);
EXPORT_SYMBOL_GPL(ata_interrupt);
EXPORT_SYMBOL_GPL(ata_mmio_data_xfer);
EXPORT_SYMBOL_GPL(ata_pio_data_xfer);
EXPORT_SYMBOL_GPL(ata_pio_data_xfer_noirq);
EXPORT_SYMBOL_GPL(ata_qc_prep);
EXPORT_SYMBOL_GPL(ata_noop_qc_prep);
EXPORT_SYMBOL_GPL(ata_bmdma_setup);
EXPORT_SYMBOL_GPL(ata_bmdma_start);
EXPORT_SYMBOL_GPL(ata_bmdma_irq_clear);
EXPORT_SYMBOL_GPL(ata_bmdma_status);
EXPORT_SYMBOL_GPL(ata_bmdma_stop);
EXPORT_SYMBOL_GPL(ata_bmdma_freeze);
EXPORT_SYMBOL_GPL(ata_bmdma_thaw);
EXPORT_SYMBOL_GPL(ata_bmdma_drive_eh);
EXPORT_SYMBOL_GPL(ata_bmdma_error_handler);
EXPORT_SYMBOL_GPL(ata_bmdma_post_internal_cmd);
EXPORT_SYMBOL_GPL(ata_port_probe);
EXPORT_SYMBOL_GPL(sata_set_spd);
EXPORT_SYMBOL_GPL(sata_phy_debounce);
EXPORT_SYMBOL_GPL(sata_phy_resume);
EXPORT_SYMBOL_GPL(sata_phy_reset);
EXPORT_SYMBOL_GPL(__sata_phy_reset);
EXPORT_SYMBOL_GPL(ata_bus_reset);
EXPORT_SYMBOL_GPL(ata_std_prereset);
EXPORT_SYMBOL_GPL(ata_std_softreset);
EXPORT_SYMBOL_GPL(sata_std_hardreset);
EXPORT_SYMBOL_GPL(ata_std_postreset);
EXPORT_SYMBOL_GPL(ata_dev_revalidate);
EXPORT_SYMBOL_GPL(ata_dev_classify);
EXPORT_SYMBOL_GPL(ata_dev_pair);
EXPORT_SYMBOL_GPL(ata_port_disable);
EXPORT_SYMBOL_GPL(ata_ratelimit);
EXPORT_SYMBOL_GPL(ata_wait_register);
EXPORT_SYMBOL_GPL(ata_busy_sleep);
EXPORT_SYMBOL_GPL(ata_port_queue_task);
EXPORT_SYMBOL_GPL(ata_scsi_ioctl);
EXPORT_SYMBOL_GPL(ata_scsi_queuecmd);
EXPORT_SYMBOL_GPL(ata_scsi_slave_config);
EXPORT_SYMBOL_GPL(ata_scsi_slave_destroy);
EXPORT_SYMBOL_GPL(ata_scsi_change_queue_depth);
EXPORT_SYMBOL_GPL(ata_scsi_release);
EXPORT_SYMBOL_GPL(ata_host_intr);
EXPORT_SYMBOL_GPL(sata_scr_valid);
EXPORT_SYMBOL_GPL(sata_scr_read);
EXPORT_SYMBOL_GPL(sata_scr_write);
EXPORT_SYMBOL_GPL(sata_scr_write_flush);
EXPORT_SYMBOL_GPL(ata_port_online);
EXPORT_SYMBOL_GPL(ata_port_offline);
EXPORT_SYMBOL_GPL(ata_id_string);
EXPORT_SYMBOL_GPL(ata_id_c_string);
EXPORT_SYMBOL_GPL(ata_scsi_simulate);

EXPORT_SYMBOL_GPL(ata_pio_need_iordy);
EXPORT_SYMBOL_GPL(ata_timing_compute);
EXPORT_SYMBOL_GPL(ata_timing_merge);

#ifdef CONFIG_PCI
EXPORT_SYMBOL_GPL(pci_test_config_bits);
EXPORT_SYMBOL_GPL(ata_pci_host_stop);
EXPORT_SYMBOL_GPL(ata_pci_init_native_mode);
EXPORT_SYMBOL_GPL(ata_pci_init_one);
EXPORT_SYMBOL_GPL(ata_pci_remove_one);
EXPORT_SYMBOL_GPL(ata_pci_device_suspend);
EXPORT_SYMBOL_GPL(ata_pci_device_resume);
EXPORT_SYMBOL_GPL(ata_pci_default_filter);
EXPORT_SYMBOL_GPL(ata_pci_clear_simplex);
#endif /* CONFIG_PCI */

EXPORT_SYMBOL_GPL(ata_device_suspend);
EXPORT_SYMBOL_GPL(ata_device_resume);
EXPORT_SYMBOL_GPL(ata_scsi_device_suspend);
EXPORT_SYMBOL_GPL(ata_scsi_device_resume);

EXPORT_SYMBOL_GPL(ata_eng_timeout);
EXPORT_SYMBOL_GPL(ata_port_schedule_eh);
EXPORT_SYMBOL_GPL(ata_port_abort);
EXPORT_SYMBOL_GPL(ata_port_freeze);
EXPORT_SYMBOL_GPL(ata_eh_freeze_port);
EXPORT_SYMBOL_GPL(ata_eh_thaw_port);
EXPORT_SYMBOL_GPL(ata_eh_qc_complete);
EXPORT_SYMBOL_GPL(ata_eh_qc_retry);
EXPORT_SYMBOL_GPL(ata_do_eh);