dmaengine: PL08x: convert to use vchan done list

[deliverable/linux.git] / drivers / dma / amba-pl08x.c

/*
 * Copyright (c) 2006 ARM Ltd.
 * Copyright (c) 2010 ST-Ericsson SA
 *
 * Author: Peter Pearse <peter.pearse@arm.com>
 * Author: Linus Walleij <linus.walleij@stericsson.com>
 *
 * 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 of the License, 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; if not, write to the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * The full GNU General Public License is in this distribution in the file
 * called COPYING.
 *
 * Documentation: ARM DDI 0196G == PL080
 * Documentation: ARM DDI 0218E == PL081
 *
 * PL080 & PL081 both have 16 sets of DMA signals that can be routed to any
 * channel.
 *
 * The PL080 has 8 channels available for simultaneous use, and the PL081
 * has only two channels. So on these DMA controllers the number of channels
 * and the number of incoming DMA signals are two totally different things.
 * It is usually not possible to theoretically handle all physical signals,
 * so a multiplexing scheme with possible denial of use is necessary.
 *
 * The PL080 has a dual bus master, PL081 has a single master.
 *
 * Memory to peripheral transfer may be visualized as
 *      Get data from memory to DMAC
 *      Until no data left
 *              On burst request from peripheral
 *                      Destination burst from DMAC to peripheral
 *                      Clear burst request
 *      Raise terminal count interrupt
 *
 * For peripherals with a FIFO:
 * Source      burst size == half the depth of the peripheral FIFO
 * Destination burst size == the depth of the peripheral FIFO
 *
 * (Bursts are irrelevant for mem to mem transfers - there are no burst
 * signals, the DMA controller will simply facilitate its AHB master.)
 *
 * ASSUMES default (little) endianness for DMA transfers
 *
 * The PL08x has two flow control settings:
 *  - DMAC flow control: the transfer size defines the number of transfers
 *    which occur for the current LLI entry, and the DMAC raises TC at the
 *    end of every LLI entry.  Observed behaviour shows the DMAC listening
 *    to both the BREQ and SREQ signals (contrary to documented),
 *    transferring data if either is active.  The LBREQ and LSREQ signals
 *    are ignored.
 *
 *  - Peripheral flow control: the transfer size is ignored (and should be
 *    zero).  The data is transferred from the current LLI entry, until
 *    after the final transfer signalled by LBREQ or LSREQ.  The DMAC
 *    will then move to the next LLI entry.
 *
 * Global TODO:
 * - Break out common code from arch/arm/mach-s3c64xx and share
 */
#include <linux/amba/bus.h>
#include <linux/amba/pl08x.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dmaengine.h>
#include <linux/dmapool.h>
#include <linux/dma-mapping.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/pm_runtime.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <asm/hardware/pl080.h>

#include "dmaengine.h"
#include "virt-dma.h"

#define DRIVER_NAME     "pl08xdmac"

static struct amba_driver pl08x_amba_driver;
struct pl08x_driver_data;

/**
 * struct vendor_data - vendor-specific config parameters for PL08x derivatives
 * @channels: the number of channels available in this variant
 * @dualmaster: whether this version supports dual AHB masters or not.
 * @nomadik: whether the channels have Nomadik security extension bits
 *      that need to be checked for permission before use and some registers are
 *      missing
 */
struct vendor_data {
        u8 channels;
        bool dualmaster;
        bool nomadik;
};

/*
 * PL08X private data structures
 * An LLI struct - see PL08x TRM.  Note that next uses bit[0] as a bus bit,
 * start & end do not - their bus bit info is in cctl.  Also note that these
 * are fixed 32-bit quantities.
 */
struct pl08x_lli {
        u32 src;
        u32 dst;
        u32 lli;
        u32 cctl;
};

/**
 * struct pl08x_bus_data - information of source or destination
 * busses for a transfer
 * @addr: current address
 * @maxwidth: the maximum width of a transfer on this bus
 * @buswidth: the width of this bus in bytes: 1, 2 or 4
 */
struct pl08x_bus_data {
        dma_addr_t addr;
        u8 maxwidth;
        u8 buswidth;
};

/**
 * struct pl08x_phy_chan - holder for the physical channels
 * @id: physical index to this channel
 * @lock: a lock to use when altering an instance of this struct
 * @serving: the virtual channel currently being served by this physical
 * channel
 * @locked: channel unavailable for the system, e.g. dedicated to secure
 * world
 */
struct pl08x_phy_chan {
        unsigned int id;
        void __iomem *base;
        spinlock_t lock;
        struct pl08x_dma_chan *serving;
        bool locked;
};

/**
 * struct pl08x_sg - structure containing data per sg
 * @src_addr: src address of sg
 * @dst_addr: dst address of sg
 * @len: transfer len in bytes
 * @node: node for txd's dsg_list
 */
struct pl08x_sg {
        dma_addr_t src_addr;
        dma_addr_t dst_addr;
        size_t len;
        struct list_head node;
};

/**
 * struct pl08x_txd - wrapper for struct dma_async_tx_descriptor
 * @vd: virtual DMA descriptor
 * @dsg_list: list of children sg's
 * @llis_bus: DMA memory address (physical) start for the LLIs
 * @llis_va: virtual memory address start for the LLIs
 * @cctl: control reg values for current txd
 * @ccfg: config reg values for current txd
 * @done: this marks completed descriptors, which should not have their
 *   mux released.
 */
struct pl08x_txd {
        struct virt_dma_desc vd;
        struct list_head dsg_list;
        dma_addr_t llis_bus;
        struct pl08x_lli *llis_va;
        /* Default cctl value for LLIs */
        u32 cctl;
        /*
         * Settings to be put into the physical channel when we
         * trigger this txd.  Other registers are in llis_va[0].
         */
        u32 ccfg;
        bool done;
};

/**
 * struct pl08x_dma_chan_state - holds the PL08x specific virtual channel
 * states
 * @PL08X_CHAN_IDLE: the channel is idle
 * @PL08X_CHAN_RUNNING: the channel has allocated a physical transport
 * channel and is running a transfer on it
 * @PL08X_CHAN_PAUSED: the channel has allocated a physical transport
 * channel, but the transfer is currently paused
 * @PL08X_CHAN_WAITING: the channel is waiting for a physical transport
 * channel to become available (only pertains to memcpy channels)
 */
enum pl08x_dma_chan_state {
        PL08X_CHAN_IDLE,
        PL08X_CHAN_RUNNING,
        PL08X_CHAN_PAUSED,
        PL08X_CHAN_WAITING,
};

/**
 * struct pl08x_dma_chan - this structure wraps a DMA ENGINE channel
 * @vc: wrappped virtual channel
 * @phychan: the physical channel utilized by this channel, if there is one
 * @name: name of channel
 * @cd: channel platform data
 * @runtime_addr: address for RX/TX according to the runtime config
 * @at: active transaction on this channel
 * @lock: a lock for this channel data
 * @host: a pointer to the host (internal use)
 * @state: whether the channel is idle, paused, running etc
 * @slave: whether this channel is a device (slave) or for memcpy
 * @signal: the physical DMA request signal which this channel is using
 * @mux_use: count of descriptors using this DMA request signal setting
 */
struct pl08x_dma_chan {
        struct virt_dma_chan vc;
        struct pl08x_phy_chan *phychan;
        const char *name;
        const struct pl08x_channel_data *cd;
        struct dma_slave_config cfg;
        struct pl08x_txd *at;
        struct pl08x_driver_data *host;
        enum pl08x_dma_chan_state state;
        bool slave;
        int signal;
        unsigned mux_use;
};

/**
 * struct pl08x_driver_data - the local state holder for the PL08x
 * @slave: slave engine for this instance
 * @memcpy: memcpy engine for this instance
 * @base: virtual memory base (remapped) for the PL08x
 * @adev: the corresponding AMBA (PrimeCell) bus entry
 * @vd: vendor data for this PL08x variant
 * @pd: platform data passed in from the platform/machine
 * @phy_chans: array of data for the physical channels
 * @pool: a pool for the LLI descriptors
 * @pool_ctr: counter of LLIs in the pool
 * @lli_buses: bitmask to or in to LLI pointer selecting AHB port for LLI
 * fetches
 * @mem_buses: set to indicate memory transfers on AHB2.
 * @lock: a spinlock for this struct
 */
struct pl08x_driver_data {
        struct dma_device slave;
        struct dma_device memcpy;
        void __iomem *base;
        struct amba_device *adev;
        const struct vendor_data *vd;
        struct pl08x_platform_data *pd;
        struct pl08x_phy_chan *phy_chans;
        struct dma_pool *pool;
        int pool_ctr;
        u8 lli_buses;
        u8 mem_buses;
};

/*
 * PL08X specific defines
 */

/* Size (bytes) of each LLI buffer allocated for one transfer */
# define PL08X_LLI_TSFR_SIZE    0x2000

/* Maximum times we call dma_pool_alloc on this pool without freeing */
#define MAX_NUM_TSFR_LLIS       (PL08X_LLI_TSFR_SIZE/sizeof(struct pl08x_lli))
#define PL08X_ALIGN             8

static inline struct pl08x_dma_chan *to_pl08x_chan(struct dma_chan *chan)
{
        return container_of(chan, struct pl08x_dma_chan, vc.chan);
}

static inline struct pl08x_txd *to_pl08x_txd(struct dma_async_tx_descriptor *tx)
{
        return container_of(tx, struct pl08x_txd, vd.tx);
}

/*
 * Mux handling.
 *
 * This gives us the DMA request input to the PL08x primecell which the
 * peripheral described by the channel data will be routed to, possibly
 * via a board/SoC specific external MUX.  One important point to note
 * here is that this does not depend on the physical channel.
 */
static int pl08x_request_mux(struct pl08x_dma_chan *plchan)
{
        const struct pl08x_platform_data *pd = plchan->host->pd;
        int ret;

        if (plchan->mux_use++ == 0 && pd->get_signal) {
                ret = pd->get_signal(plchan->cd);
                if (ret < 0) {
                        plchan->mux_use = 0;
                        return ret;
                }

                plchan->signal = ret;
        }
        return 0;
}

static void pl08x_release_mux(struct pl08x_dma_chan *plchan)
{
        const struct pl08x_platform_data *pd = plchan->host->pd;

        if (plchan->signal >= 0) {
                WARN_ON(plchan->mux_use == 0);

                if (--plchan->mux_use == 0 && pd->put_signal) {
                        pd->put_signal(plchan->cd, plchan->signal);
                        plchan->signal = -1;
                }
        }
}

/*
 * Physical channel handling
 */

/* Whether a certain channel is busy or not */
static int pl08x_phy_channel_busy(struct pl08x_phy_chan *ch)
{
        unsigned int val;

        val = readl(ch->base + PL080_CH_CONFIG);
        return val & PL080_CONFIG_ACTIVE;
}

/*
 * Set the initial DMA register values i.e. those for the first LLI
 * The next LLI pointer and the configuration interrupt bit have
 * been set when the LLIs were constructed.  Poke them into the hardware
 * and start the transfer.
 */
static void pl08x_start_next_txd(struct pl08x_dma_chan *plchan)
{
        struct pl08x_driver_data *pl08x = plchan->host;
        struct pl08x_phy_chan *phychan = plchan->phychan;
        struct virt_dma_desc *vd = vchan_next_desc(&plchan->vc);
        struct pl08x_txd *txd = to_pl08x_txd(&vd->tx);
        struct pl08x_lli *lli;
        u32 val;

        list_del(&txd->vd.node);

        plchan->at = txd;

        /* Wait for channel inactive */
        while (pl08x_phy_channel_busy(phychan))
                cpu_relax();

        lli = &txd->llis_va[0];

        dev_vdbg(&pl08x->adev->dev,
                "WRITE channel %d: csrc=0x%08x, cdst=0x%08x, "
                "clli=0x%08x, cctl=0x%08x, ccfg=0x%08x\n",
                phychan->id, lli->src, lli->dst, lli->lli, lli->cctl,
                txd->ccfg);

        writel(lli->src, phychan->base + PL080_CH_SRC_ADDR);
        writel(lli->dst, phychan->base + PL080_CH_DST_ADDR);
        writel(lli->lli, phychan->base + PL080_CH_LLI);
        writel(lli->cctl, phychan->base + PL080_CH_CONTROL);
        writel(txd->ccfg, phychan->base + PL080_CH_CONFIG);

        /* Enable the DMA channel */
        /* Do not access config register until channel shows as disabled */
        while (readl(pl08x->base + PL080_EN_CHAN) & (1 << phychan->id))
                cpu_relax();

        /* Do not access config register until channel shows as inactive */
        val = readl(phychan->base + PL080_CH_CONFIG);
        while ((val & PL080_CONFIG_ACTIVE) || (val & PL080_CONFIG_ENABLE))
                val = readl(phychan->base + PL080_CH_CONFIG);

        writel(val | PL080_CONFIG_ENABLE, phychan->base + PL080_CH_CONFIG);
}

/*
 * Pause the channel by setting the HALT bit.
 *
 * For M->P transfers, pause the DMAC first and then stop the peripheral -
 * the FIFO can only drain if the peripheral is still requesting data.
 * (note: this can still timeout if the DMAC FIFO never drains of data.)
 *
 * For P->M transfers, disable the peripheral first to stop it filling
 * the DMAC FIFO, and then pause the DMAC.
 */
static void pl08x_pause_phy_chan(struct pl08x_phy_chan *ch)
{
        u32 val;
        int timeout;

        /* Set the HALT bit and wait for the FIFO to drain */
        val = readl(ch->base + PL080_CH_CONFIG);
        val |= PL080_CONFIG_HALT;
        writel(val, ch->base + PL080_CH_CONFIG);

        /* Wait for channel inactive */
        for (timeout = 1000; timeout; timeout--) {
                if (!pl08x_phy_channel_busy(ch))
                        break;
                udelay(1);
        }
        if (pl08x_phy_channel_busy(ch))
                pr_err("pl08x: channel%u timeout waiting for pause\n", ch->id);
}

static void pl08x_resume_phy_chan(struct pl08x_phy_chan *ch)
{
        u32 val;

        /* Clear the HALT bit */
        val = readl(ch->base + PL080_CH_CONFIG);
        val &= ~PL080_CONFIG_HALT;
        writel(val, ch->base + PL080_CH_CONFIG);
}

/*
 * pl08x_terminate_phy_chan() stops the channel, clears the FIFO and
 * clears any pending interrupt status.  This should not be used for
 * an on-going transfer, but as a method of shutting down a channel
 * (eg, when it's no longer used) or terminating a transfer.
 */
static void pl08x_terminate_phy_chan(struct pl08x_driver_data *pl08x,
        struct pl08x_phy_chan *ch)
{
        u32 val = readl(ch->base + PL080_CH_CONFIG);

        val &= ~(PL080_CONFIG_ENABLE | PL080_CONFIG_ERR_IRQ_MASK |
                 PL080_CONFIG_TC_IRQ_MASK);

        writel(val, ch->base + PL080_CH_CONFIG);

        writel(1 << ch->id, pl08x->base + PL080_ERR_CLEAR);
        writel(1 << ch->id, pl08x->base + PL080_TC_CLEAR);
}

static inline u32 get_bytes_in_cctl(u32 cctl)
{
        /* The source width defines the number of bytes */
        u32 bytes = cctl & PL080_CONTROL_TRANSFER_SIZE_MASK;

        switch (cctl >> PL080_CONTROL_SWIDTH_SHIFT) {
        case PL080_WIDTH_8BIT:
                break;
        case PL080_WIDTH_16BIT:
                bytes *= 2;
                break;
        case PL080_WIDTH_32BIT:
                bytes *= 4;
                break;
        }
        return bytes;
}

/* The channel should be paused when calling this */
static u32 pl08x_getbytes_chan(struct pl08x_dma_chan *plchan)
{
        struct pl08x_phy_chan *ch;
        struct pl08x_txd *txd;
        unsigned long flags;
        size_t bytes = 0;

        spin_lock_irqsave(&plchan->vc.lock, flags);
        ch = plchan->phychan;
        txd = plchan->at;

        /*
         * Follow the LLIs to get the number of remaining
         * bytes in the currently active transaction.
         */
        if (ch && txd) {
                u32 clli = readl(ch->base + PL080_CH_LLI) & ~PL080_LLI_LM_AHB2;

                /* First get the remaining bytes in the active transfer */
                bytes = get_bytes_in_cctl(readl(ch->base + PL080_CH_CONTROL));

                if (clli) {
                        struct pl08x_lli *llis_va = txd->llis_va;
                        dma_addr_t llis_bus = txd->llis_bus;
                        int index;

                        BUG_ON(clli < llis_bus || clli >= llis_bus +
                                sizeof(struct pl08x_lli) * MAX_NUM_TSFR_LLIS);

                        /*
                         * Locate the next LLI - as this is an array,
                         * it's simple maths to find.
                         */
                        index = (clli - llis_bus) / sizeof(struct pl08x_lli);

                        for (; index < MAX_NUM_TSFR_LLIS; index++) {
                                bytes += get_bytes_in_cctl(llis_va[index].cctl);

                                /*
                                 * A LLI pointer of 0 terminates the LLI list
                                 */
                                if (!llis_va[index].lli)
                                        break;
                        }
                }
        }

        /* Sum up all queued transactions */
        if (!list_empty(&plchan->vc.desc_issued)) {
                struct pl08x_txd *txdi;
                list_for_each_entry(txdi, &plchan->vc.desc_issued, vd.node) {
                        struct pl08x_sg *dsg;
                        list_for_each_entry(dsg, &txd->dsg_list, node)
                                bytes += dsg->len;
                }
        }

        if (!list_empty(&plchan->vc.desc_submitted)) {
                struct pl08x_txd *txdi;
                list_for_each_entry(txdi, &plchan->vc.desc_submitted, vd.node) {
                        struct pl08x_sg *dsg;
                        list_for_each_entry(dsg, &txd->dsg_list, node)
                                bytes += dsg->len;
                }
        }

        spin_unlock_irqrestore(&plchan->vc.lock, flags);

        return bytes;
}

/*
 * Allocate a physical channel for a virtual channel
 *
 * Try to locate a physical channel to be used for this transfer. If all
 * are taken return NULL and the requester will have to cope by using
 * some fallback PIO mode or retrying later.
 */
static struct pl08x_phy_chan *
pl08x_get_phy_channel(struct pl08x_driver_data *pl08x,
                      struct pl08x_dma_chan *virt_chan)
{
        struct pl08x_phy_chan *ch = NULL;
        unsigned long flags;
        int i;

        for (i = 0; i < pl08x->vd->channels; i++) {
                ch = &pl08x->phy_chans[i];

                spin_lock_irqsave(&ch->lock, flags);

                if (!ch->locked && !ch->serving) {
                        ch->serving = virt_chan;
                        spin_unlock_irqrestore(&ch->lock, flags);
                        break;
                }

                spin_unlock_irqrestore(&ch->lock, flags);
        }

        if (i == pl08x->vd->channels) {
                /* No physical channel available, cope with it */
                return NULL;
        }

        return ch;
}

/* Mark the physical channel as free.  Note, this write is atomic. */
static inline void pl08x_put_phy_channel(struct pl08x_driver_data *pl08x,
                                         struct pl08x_phy_chan *ch)
{
        ch->serving = NULL;
}

/*
 * Try to allocate a physical channel.  When successful, assign it to
 * this virtual channel, and initiate the next descriptor.  The
 * virtual channel lock must be held at this point.
 */
static void pl08x_phy_alloc_and_start(struct pl08x_dma_chan *plchan)
{
        struct pl08x_driver_data *pl08x = plchan->host;
        struct pl08x_phy_chan *ch;

        ch = pl08x_get_phy_channel(pl08x, plchan);
        if (!ch) {
                dev_dbg(&pl08x->adev->dev, "no physical channel available for xfer on %s\n", plchan->name);
                plchan->state = PL08X_CHAN_WAITING;
                return;
        }

        dev_dbg(&pl08x->adev->dev, "allocated physical channel %d for xfer on %s\n",
                ch->id, plchan->name);

        plchan->phychan = ch;
        plchan->state = PL08X_CHAN_RUNNING;
        pl08x_start_next_txd(plchan);
}

static void pl08x_phy_reassign_start(struct pl08x_phy_chan *ch,
        struct pl08x_dma_chan *plchan)
{
        struct pl08x_driver_data *pl08x = plchan->host;

        dev_dbg(&pl08x->adev->dev, "reassigned physical channel %d for xfer on %s\n",
                ch->id, plchan->name);

        /*
         * We do this without taking the lock; we're really only concerned
         * about whether this pointer is NULL or not, and we're guaranteed
         * that this will only be called when it _already_ is non-NULL.
         */
        ch->serving = plchan;
        plchan->phychan = ch;
        plchan->state = PL08X_CHAN_RUNNING;
        pl08x_start_next_txd(plchan);
}

/*
 * Free a physical DMA channel, potentially reallocating it to another
 * virtual channel if we have any pending.
 */
static void pl08x_phy_free(struct pl08x_dma_chan *plchan)
{
        struct pl08x_driver_data *pl08x = plchan->host;
        struct pl08x_dma_chan *p, *next;

 retry:
        next = NULL;

        /* Find a waiting virtual channel for the next transfer. */
        list_for_each_entry(p, &pl08x->memcpy.channels, vc.chan.device_node)
                if (p->state == PL08X_CHAN_WAITING) {
                        next = p;
                        break;
                }

        if (!next) {
                list_for_each_entry(p, &pl08x->slave.channels, vc.chan.device_node)
                        if (p->state == PL08X_CHAN_WAITING) {
                                next = p;
                                break;
                        }
        }

        /* Ensure that the physical channel is stopped */
        pl08x_terminate_phy_chan(pl08x, plchan->phychan);

        if (next) {
                bool success;

                /*
                 * Eww.  We know this isn't going to deadlock
                 * but lockdep probably doesn't.
                 */
                spin_lock(&next->vc.lock);
                /* Re-check the state now that we have the lock */
                success = next->state == PL08X_CHAN_WAITING;
                if (success)
                        pl08x_phy_reassign_start(plchan->phychan, next);
                spin_unlock(&next->vc.lock);

                /* If the state changed, try to find another channel */
                if (!success)
                        goto retry;
        } else {
                /* No more jobs, so free up the physical channel */
                pl08x_put_phy_channel(pl08x, plchan->phychan);
        }

        plchan->phychan = NULL;
        plchan->state = PL08X_CHAN_IDLE;
}

/*
 * LLI handling
 */

static inline unsigned int pl08x_get_bytes_for_cctl(unsigned int coded)
{
        switch (coded) {
        case PL080_WIDTH_8BIT:
                return 1;
        case PL080_WIDTH_16BIT:
                return 2;
        case PL080_WIDTH_32BIT:
                return 4;
        default:
                break;
        }
        BUG();
        return 0;
}

static inline u32 pl08x_cctl_bits(u32 cctl, u8 srcwidth, u8 dstwidth,
                                  size_t tsize)
{
        u32 retbits = cctl;

        /* Remove all src, dst and transfer size bits */
        retbits &= ~PL080_CONTROL_DWIDTH_MASK;
        retbits &= ~PL080_CONTROL_SWIDTH_MASK;
        retbits &= ~PL080_CONTROL_TRANSFER_SIZE_MASK;

        /* Then set the bits according to the parameters */
        switch (srcwidth) {
        case 1:
                retbits |= PL080_WIDTH_8BIT << PL080_CONTROL_SWIDTH_SHIFT;
                break;
        case 2:
                retbits |= PL080_WIDTH_16BIT << PL080_CONTROL_SWIDTH_SHIFT;
                break;
        case 4:
                retbits |= PL080_WIDTH_32BIT << PL080_CONTROL_SWIDTH_SHIFT;
                break;
        default:
                BUG();
                break;
        }

        switch (dstwidth) {
        case 1:
                retbits |= PL080_WIDTH_8BIT << PL080_CONTROL_DWIDTH_SHIFT;
                break;
        case 2:
                retbits |= PL080_WIDTH_16BIT << PL080_CONTROL_DWIDTH_SHIFT;
                break;
        case 4:
                retbits |= PL080_WIDTH_32BIT << PL080_CONTROL_DWIDTH_SHIFT;
                break;
        default:
                BUG();
                break;
        }

        retbits |= tsize << PL080_CONTROL_TRANSFER_SIZE_SHIFT;
        return retbits;
}

struct pl08x_lli_build_data {
        struct pl08x_txd *txd;
        struct pl08x_bus_data srcbus;
        struct pl08x_bus_data dstbus;
        size_t remainder;
        u32 lli_bus;
};

/*
 * Autoselect a master bus to use for the transfer. Slave will be the chosen as
 * victim in case src & dest are not similarly aligned. i.e. If after aligning
 * masters address with width requirements of transfer (by sending few byte by
 * byte data), slave is still not aligned, then its width will be reduced to
 * BYTE.
 * - prefers the destination bus if both available
 * - prefers bus with fixed address (i.e. peripheral)
 */
static void pl08x_choose_master_bus(struct pl08x_lli_build_data *bd,
        struct pl08x_bus_data **mbus, struct pl08x_bus_data **sbus, u32 cctl)
{
        if (!(cctl & PL080_CONTROL_DST_INCR)) {
                *mbus = &bd->dstbus;
                *sbus = &bd->srcbus;
        } else if (!(cctl & PL080_CONTROL_SRC_INCR)) {
                *mbus = &bd->srcbus;
                *sbus = &bd->dstbus;
        } else {
                if (bd->dstbus.buswidth >= bd->srcbus.buswidth) {
                        *mbus = &bd->dstbus;
                        *sbus = &bd->srcbus;
                } else {
                        *mbus = &bd->srcbus;
                        *sbus = &bd->dstbus;
                }
        }
}

/*
 * Fills in one LLI for a certain transfer descriptor and advance the counter
 */
static void pl08x_fill_lli_for_desc(struct pl08x_lli_build_data *bd,
        int num_llis, int len, u32 cctl)
{
        struct pl08x_lli *llis_va = bd->txd->llis_va;
        dma_addr_t llis_bus = bd->txd->llis_bus;

        BUG_ON(num_llis >= MAX_NUM_TSFR_LLIS);

        llis_va[num_llis].cctl = cctl;
        llis_va[num_llis].src = bd->srcbus.addr;
        llis_va[num_llis].dst = bd->dstbus.addr;
        llis_va[num_llis].lli = llis_bus + (num_llis + 1) *
                sizeof(struct pl08x_lli);
        llis_va[num_llis].lli |= bd->lli_bus;

        if (cctl & PL080_CONTROL_SRC_INCR)
                bd->srcbus.addr += len;
        if (cctl & PL080_CONTROL_DST_INCR)
                bd->dstbus.addr += len;

        BUG_ON(bd->remainder < len);

        bd->remainder -= len;
}

static inline void prep_byte_width_lli(struct pl08x_lli_build_data *bd,
                u32 *cctl, u32 len, int num_llis, size_t *total_bytes)
{
        *cctl = pl08x_cctl_bits(*cctl, 1, 1, len);
        pl08x_fill_lli_for_desc(bd, num_llis, len, *cctl);
        (*total_bytes) += len;
}

/*
 * This fills in the table of LLIs for the transfer descriptor
 * Note that we assume we never have to change the burst sizes
 * Return 0 for error
 */
static int pl08x_fill_llis_for_desc(struct pl08x_driver_data *pl08x,
                              struct pl08x_txd *txd)
{
        struct pl08x_bus_data *mbus, *sbus;
        struct pl08x_lli_build_data bd;
        int num_llis = 0;
        u32 cctl, early_bytes = 0;
        size_t max_bytes_per_lli, total_bytes;
        struct pl08x_lli *llis_va;
        struct pl08x_sg *dsg;

        txd->llis_va = dma_pool_alloc(pl08x->pool, GFP_NOWAIT, &txd->llis_bus);
        if (!txd->llis_va) {
                dev_err(&pl08x->adev->dev, "%s no memory for llis\n", __func__);
                return 0;
        }

        pl08x->pool_ctr++;

        bd.txd = txd;
        bd.lli_bus = (pl08x->lli_buses & PL08X_AHB2) ? PL080_LLI_LM_AHB2 : 0;
        cctl = txd->cctl;

        /* Find maximum width of the source bus */
        bd.srcbus.maxwidth =
                pl08x_get_bytes_for_cctl((cctl & PL080_CONTROL_SWIDTH_MASK) >>
                                       PL080_CONTROL_SWIDTH_SHIFT);

        /* Find maximum width of the destination bus */
        bd.dstbus.maxwidth =
                pl08x_get_bytes_for_cctl((cctl & PL080_CONTROL_DWIDTH_MASK) >>
                                       PL080_CONTROL_DWIDTH_SHIFT);

        list_for_each_entry(dsg, &txd->dsg_list, node) {
                total_bytes = 0;
                cctl = txd->cctl;

                bd.srcbus.addr = dsg->src_addr;
                bd.dstbus.addr = dsg->dst_addr;
                bd.remainder = dsg->len;
                bd.srcbus.buswidth = bd.srcbus.maxwidth;
                bd.dstbus.buswidth = bd.dstbus.maxwidth;

                pl08x_choose_master_bus(&bd, &mbus, &sbus, cctl);

                dev_vdbg(&pl08x->adev->dev, "src=0x%08x%s/%u dst=0x%08x%s/%u len=%zu\n",
                        bd.srcbus.addr, cctl & PL080_CONTROL_SRC_INCR ? "+" : "",
                        bd.srcbus.buswidth,
                        bd.dstbus.addr, cctl & PL080_CONTROL_DST_INCR ? "+" : "",
                        bd.dstbus.buswidth,
                        bd.remainder);
                dev_vdbg(&pl08x->adev->dev, "mbus=%s sbus=%s\n",
                        mbus == &bd.srcbus ? "src" : "dst",
                        sbus == &bd.srcbus ? "src" : "dst");

                /*
                 * Zero length is only allowed if all these requirements are
                 * met:
                 * - flow controller is peripheral.
                 * - src.addr is aligned to src.width
                 * - dst.addr is aligned to dst.width
                 *
                 * sg_len == 1 should be true, as there can be two cases here:
                 *
                 * - Memory addresses are contiguous and are not scattered.
                 *   Here, Only one sg will be passed by user driver, with
                 *   memory address and zero length. We pass this to controller
                 *   and after the transfer it will receive the last burst
                 *   request from peripheral and so transfer finishes.
                 *
                 * - Memory addresses are scattered and are not contiguous.
                 *   Here, Obviously as DMA controller doesn't know when a lli's
                 *   transfer gets over, it can't load next lli. So in this
                 *   case, there has to be an assumption that only one lli is
                 *   supported. Thus, we can't have scattered addresses.
                 */
                if (!bd.remainder) {
                        u32 fc = (txd->ccfg & PL080_CONFIG_FLOW_CONTROL_MASK) >>
                                PL080_CONFIG_FLOW_CONTROL_SHIFT;
                        if (!((fc >= PL080_FLOW_SRC2DST_DST) &&
                                        (fc <= PL080_FLOW_SRC2DST_SRC))) {
                                dev_err(&pl08x->adev->dev, "%s sg len can't be zero",
                                        __func__);
                                return 0;
                        }

                        if ((bd.srcbus.addr % bd.srcbus.buswidth) ||
                                        (bd.dstbus.addr % bd.dstbus.buswidth)) {
                                dev_err(&pl08x->adev->dev,
                                        "%s src & dst address must be aligned to src"
                                        " & dst width if peripheral is flow controller",
                                        __func__);
                                return 0;
                        }

                        cctl = pl08x_cctl_bits(cctl, bd.srcbus.buswidth,
                                        bd.dstbus.buswidth, 0);
                        pl08x_fill_lli_for_desc(&bd, num_llis++, 0, cctl);
                        break;
                }

                /*
                 * Send byte by byte for following cases
                 * - Less than a bus width available
                 * - until master bus is aligned
                 */
                if (bd.remainder < mbus->buswidth)
                        early_bytes = bd.remainder;
                else if ((mbus->addr) % (mbus->buswidth)) {
                        early_bytes = mbus->buswidth - (mbus->addr) %
                                (mbus->buswidth);
                        if ((bd.remainder - early_bytes) < mbus->buswidth)
                                early_bytes = bd.remainder;
                }

                if (early_bytes) {
                        dev_vdbg(&pl08x->adev->dev,
                                "%s byte width LLIs (remain 0x%08x)\n",
                                __func__, bd.remainder);
                        prep_byte_width_lli(&bd, &cctl, early_bytes, num_llis++,
                                &total_bytes);
                }

                if (bd.remainder) {
                        /*
                         * Master now aligned
                         * - if slave is not then we must set its width down
                         */
                        if (sbus->addr % sbus->buswidth) {
                                dev_dbg(&pl08x->adev->dev,
                                        "%s set down bus width to one byte\n",
                                        __func__);

                                sbus->buswidth = 1;
                        }

                        /*
                         * Bytes transferred = tsize * src width, not
                         * MIN(buswidths)
                         */
                        max_bytes_per_lli = bd.srcbus.buswidth *
                                PL080_CONTROL_TRANSFER_SIZE_MASK;
                        dev_vdbg(&pl08x->adev->dev,
                                "%s max bytes per lli = %zu\n",
                                __func__, max_bytes_per_lli);

                        /*
                         * Make largest possible LLIs until less than one bus
                         * width left
                         */
                        while (bd.remainder > (mbus->buswidth - 1)) {
                                size_t lli_len, tsize, width;

                                /*
                                 * If enough left try to send max possible,
                                 * otherwise try to send the remainder
                                 */
                                lli_len = min(bd.remainder, max_bytes_per_lli);

                                /*
                                 * Check against maximum bus alignment:
                                 * Calculate actual transfer size in relation to
                                 * bus width an get a maximum remainder of the
                                 * highest bus width - 1
                                 */
                                width = max(mbus->buswidth, sbus->buswidth);
                                lli_len = (lli_len / width) * width;
                                tsize = lli_len / bd.srcbus.buswidth;

                                dev_vdbg(&pl08x->adev->dev,
                                        "%s fill lli with single lli chunk of "
                                        "size 0x%08zx (remainder 0x%08zx)\n",
                                        __func__, lli_len, bd.remainder);

                                cctl = pl08x_cctl_bits(cctl, bd.srcbus.buswidth,
                                        bd.dstbus.buswidth, tsize);
                                pl08x_fill_lli_for_desc(&bd, num_llis++,
                                                lli_len, cctl);
                                total_bytes += lli_len;
                        }

                        /*
                         * Send any odd bytes
                         */
                        if (bd.remainder) {
                                dev_vdbg(&pl08x->adev->dev,
                                        "%s align with boundary, send odd bytes (remain %zu)\n",
                                        __func__, bd.remainder);
                                prep_byte_width_lli(&bd, &cctl, bd.remainder,
                                                num_llis++, &total_bytes);
                        }
                }

                if (total_bytes != dsg->len) {
                        dev_err(&pl08x->adev->dev,
                                "%s size of encoded lli:s don't match total txd, transferred 0x%08zx from size 0x%08zx\n",
                                __func__, total_bytes, dsg->len);
                        return 0;
                }

                if (num_llis >= MAX_NUM_TSFR_LLIS) {
                        dev_err(&pl08x->adev->dev,
                                "%s need to increase MAX_NUM_TSFR_LLIS from 0x%08x\n",
                                __func__, (u32) MAX_NUM_TSFR_LLIS);
                        return 0;
                }
        }

        llis_va = txd->llis_va;
        /* The final LLI terminates the LLI. */
        llis_va[num_llis - 1].lli = 0;
        /* The final LLI element shall also fire an interrupt. */
        llis_va[num_llis - 1].cctl |= PL080_CONTROL_TC_IRQ_EN;

#ifdef VERBOSE_DEBUG
        {
                int i;

                dev_vdbg(&pl08x->adev->dev,
                         "%-3s %-9s  %-10s %-10s %-10s %s\n",
                         "lli", "", "csrc", "cdst", "clli", "cctl");
                for (i = 0; i < num_llis; i++) {
                        dev_vdbg(&pl08x->adev->dev,
                                 "%3d @%p: 0x%08x 0x%08x 0x%08x 0x%08x\n",
                                 i, &llis_va[i], llis_va[i].src,
                                 llis_va[i].dst, llis_va[i].lli, llis_va[i].cctl
                                );
                }
        }
#endif

        return num_llis;
}

/* You should call this with the struct pl08x lock held */
static void pl08x_free_txd(struct pl08x_driver_data *pl08x,
                           struct pl08x_txd *txd)
{
        struct pl08x_sg *dsg, *_dsg;

        /* Free the LLI */
        if (txd->llis_va)
                dma_pool_free(pl08x->pool, txd->llis_va, txd->llis_bus);

        pl08x->pool_ctr--;

        list_for_each_entry_safe(dsg, _dsg, &txd->dsg_list, node) {
                list_del(&dsg->node);
                kfree(dsg);
        }

        kfree(txd);
}

static void pl08x_unmap_buffers(struct pl08x_txd *txd)
{
        struct device *dev = txd->vd.tx.chan->device->dev;
        struct pl08x_sg *dsg;

        if (!(txd->vd.tx.flags & DMA_COMPL_SKIP_SRC_UNMAP)) {
                if (txd->vd.tx.flags & DMA_COMPL_SRC_UNMAP_SINGLE)
                        list_for_each_entry(dsg, &txd->dsg_list, node)
                                dma_unmap_single(dev, dsg->src_addr, dsg->len,
                                                DMA_TO_DEVICE);
                else {
                        list_for_each_entry(dsg, &txd->dsg_list, node)
                                dma_unmap_page(dev, dsg->src_addr, dsg->len,
                                                DMA_TO_DEVICE);
                }
        }
        if (!(txd->vd.tx.flags & DMA_COMPL_SKIP_DEST_UNMAP)) {
                if (txd->vd.tx.flags & DMA_COMPL_DEST_UNMAP_SINGLE)
                        list_for_each_entry(dsg, &txd->dsg_list, node)
                                dma_unmap_single(dev, dsg->dst_addr, dsg->len,
                                                DMA_FROM_DEVICE);
                else
                        list_for_each_entry(dsg, &txd->dsg_list, node)
                                dma_unmap_page(dev, dsg->dst_addr, dsg->len,
                                                DMA_FROM_DEVICE);
        }
}

static void pl08x_desc_free(struct virt_dma_desc *vd)
{
        struct pl08x_txd *txd = to_pl08x_txd(&vd->tx);
        struct pl08x_dma_chan *plchan = to_pl08x_chan(vd->tx.chan);
        struct pl08x_driver_data *pl08x = plchan->host;
        unsigned long flags;

        if (!plchan->slave)
                pl08x_unmap_buffers(txd);

        if (!txd->done)
                pl08x_release_mux(plchan);

        spin_lock_irqsave(&pl08x->lock, flags);
        pl08x_free_txd(plchan->host, txd);
        spin_unlock_irqrestore(&pl08x->lock, flags);
}

static void pl08x_free_txd_list(struct pl08x_driver_data *pl08x,
                                struct pl08x_dma_chan *plchan)
{
        LIST_HEAD(head);
        struct pl08x_txd *txd;

        vchan_get_all_descriptors(&plchan->vc, &head);

        while (!list_empty(&head)) {
                txd = list_first_entry(&head, struct pl08x_txd, vd.node);
                list_del(&txd->vd.node);
                pl08x_desc_free(&txd->vd);
        }
}

/*
 * The DMA ENGINE API
 */
static int pl08x_alloc_chan_resources(struct dma_chan *chan)
{
        return 0;
}

static void pl08x_free_chan_resources(struct dma_chan *chan)
{
}

static struct dma_async_tx_descriptor *pl08x_prep_dma_interrupt(
                struct dma_chan *chan, unsigned long flags)
{
        struct dma_async_tx_descriptor *retval = NULL;

        return retval;
}

/*
 * Code accessing dma_async_is_complete() in a tight loop may give problems.
 * If slaves are relying on interrupts to signal completion this function
 * must not be called with interrupts disabled.
 */
static enum dma_status pl08x_dma_tx_status(struct dma_chan *chan,
                dma_cookie_t cookie, struct dma_tx_state *txstate)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
        enum dma_status ret;

        ret = dma_cookie_status(chan, cookie, txstate);
        if (ret == DMA_SUCCESS)
                return ret;

        /*
         * This cookie not complete yet
         * Get number of bytes left in the active transactions and queue
         */
        dma_set_residue(txstate, pl08x_getbytes_chan(plchan));

        if (plchan->state == PL08X_CHAN_PAUSED)
                return DMA_PAUSED;

        /* Whether waiting or running, we're in progress */
        return DMA_IN_PROGRESS;
}

/* PrimeCell DMA extension */
struct burst_table {
        u32 burstwords;
        u32 reg;
};

static const struct burst_table burst_sizes[] = {
        {
                .burstwords = 256,
                .reg = PL080_BSIZE_256,
        },
        {
                .burstwords = 128,
                .reg = PL080_BSIZE_128,
        },
        {
                .burstwords = 64,
                .reg = PL080_BSIZE_64,
        },
        {
                .burstwords = 32,
                .reg = PL080_BSIZE_32,
        },
        {
                .burstwords = 16,
                .reg = PL080_BSIZE_16,
        },
        {
                .burstwords = 8,
                .reg = PL080_BSIZE_8,
        },
        {
                .burstwords = 4,
                .reg = PL080_BSIZE_4,
        },
        {
                .burstwords = 0,
                .reg = PL080_BSIZE_1,
        },
};

/*
 * Given the source and destination available bus masks, select which
 * will be routed to each port.  We try to have source and destination
 * on separate ports, but always respect the allowable settings.
 */
static u32 pl08x_select_bus(u8 src, u8 dst)
{
        u32 cctl = 0;

        if (!(dst & PL08X_AHB1) || ((dst & PL08X_AHB2) && (src & PL08X_AHB1)))
                cctl |= PL080_CONTROL_DST_AHB2;
        if (!(src & PL08X_AHB1) || ((src & PL08X_AHB2) && !(dst & PL08X_AHB2)))
                cctl |= PL080_CONTROL_SRC_AHB2;

        return cctl;
}

static u32 pl08x_cctl(u32 cctl)
{
        cctl &= ~(PL080_CONTROL_SRC_AHB2 | PL080_CONTROL_DST_AHB2 |
                  PL080_CONTROL_SRC_INCR | PL080_CONTROL_DST_INCR |
                  PL080_CONTROL_PROT_MASK);

        /* Access the cell in privileged mode, non-bufferable, non-cacheable */
        return cctl | PL080_CONTROL_PROT_SYS;
}

static u32 pl08x_width(enum dma_slave_buswidth width)
{
        switch (width) {
        case DMA_SLAVE_BUSWIDTH_1_BYTE:
                return PL080_WIDTH_8BIT;
        case DMA_SLAVE_BUSWIDTH_2_BYTES:
                return PL080_WIDTH_16BIT;
        case DMA_SLAVE_BUSWIDTH_4_BYTES:
                return PL080_WIDTH_32BIT;
        default:
                return ~0;
        }
}

static u32 pl08x_burst(u32 maxburst)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(burst_sizes); i++)
                if (burst_sizes[i].burstwords <= maxburst)
                        break;

        return burst_sizes[i].reg;
}

static u32 pl08x_get_cctl(struct pl08x_dma_chan *plchan,
        enum dma_slave_buswidth addr_width, u32 maxburst)
{
        u32 width, burst, cctl = 0;

        width = pl08x_width(addr_width);
        if (width == ~0)
                return ~0;

        cctl |= width << PL080_CONTROL_SWIDTH_SHIFT;
        cctl |= width << PL080_CONTROL_DWIDTH_SHIFT;

        /*
         * If this channel will only request single transfers, set this
         * down to ONE element.  Also select one element if no maxburst
         * is specified.
         */
        if (plchan->cd->single)
                maxburst = 1;

        burst = pl08x_burst(maxburst);
        cctl |= burst << PL080_CONTROL_SB_SIZE_SHIFT;
        cctl |= burst << PL080_CONTROL_DB_SIZE_SHIFT;

        return pl08x_cctl(cctl);
}

static int dma_set_runtime_config(struct dma_chan *chan,
                                  struct dma_slave_config *config)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);

        if (!plchan->slave)
                return -EINVAL;

        /* Reject definitely invalid configurations */
        if (config->src_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES ||
            config->dst_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES)
                return -EINVAL;

        plchan->cfg = *config;

        return 0;
}

/*
 * Slave transactions callback to the slave device to allow
 * synchronization of slave DMA signals with the DMAC enable
 */
static void pl08x_issue_pending(struct dma_chan *chan)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
        unsigned long flags;

        spin_lock_irqsave(&plchan->vc.lock, flags);
        if (vchan_issue_pending(&plchan->vc)) {
                if (!plchan->phychan && plchan->state != PL08X_CHAN_WAITING)
                        pl08x_phy_alloc_and_start(plchan);
        }
        spin_unlock_irqrestore(&plchan->vc.lock, flags);
}

static int pl08x_prep_channel_resources(struct pl08x_dma_chan *plchan,
                                        struct pl08x_txd *txd)
{
        struct pl08x_driver_data *pl08x = plchan->host;
        int num_llis;

        num_llis = pl08x_fill_llis_for_desc(pl08x, txd);
        if (!num_llis) {
                unsigned long flags;

                spin_lock_irqsave(&plchan->vc.lock, flags);
                pl08x_free_txd(pl08x, txd);
                spin_unlock_irqrestore(&plchan->vc.lock, flags);

                return -EINVAL;
        }
        return 0;
}

static struct pl08x_txd *pl08x_get_txd(struct pl08x_dma_chan *plchan)
{
        struct pl08x_txd *txd = kzalloc(sizeof(*txd), GFP_NOWAIT);

        if (txd) {
                INIT_LIST_HEAD(&txd->dsg_list);

                /* Always enable error and terminal interrupts */
                txd->ccfg = PL080_CONFIG_ERR_IRQ_MASK |
                            PL080_CONFIG_TC_IRQ_MASK;
        }
        return txd;
}

/*
 * Initialize a descriptor to be used by memcpy submit
 */
static struct dma_async_tx_descriptor *pl08x_prep_dma_memcpy(
                struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
                size_t len, unsigned long flags)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
        struct pl08x_driver_data *pl08x = plchan->host;
        struct pl08x_txd *txd;
        struct pl08x_sg *dsg;
        int ret;

        txd = pl08x_get_txd(plchan);
        if (!txd) {
                dev_err(&pl08x->adev->dev,
                        "%s no memory for descriptor\n", __func__);
                return NULL;
        }

        dsg = kzalloc(sizeof(struct pl08x_sg), GFP_NOWAIT);
        if (!dsg) {
                pl08x_free_txd(pl08x, txd);
                dev_err(&pl08x->adev->dev, "%s no memory for pl080 sg\n",
                                __func__);
                return NULL;
        }
        list_add_tail(&dsg->node, &txd->dsg_list);

        dsg->src_addr = src;
        dsg->dst_addr = dest;
        dsg->len = len;

        /* Set platform data for m2m */
        txd->ccfg |= PL080_FLOW_MEM2MEM << PL080_CONFIG_FLOW_CONTROL_SHIFT;
        txd->cctl = pl08x->pd->memcpy_channel.cctl_memcpy &
                        ~(PL080_CONTROL_DST_AHB2 | PL080_CONTROL_SRC_AHB2);

        /* Both to be incremented or the code will break */
        txd->cctl |= PL080_CONTROL_SRC_INCR | PL080_CONTROL_DST_INCR;

        if (pl08x->vd->dualmaster)
                txd->cctl |= pl08x_select_bus(pl08x->mem_buses,
                                              pl08x->mem_buses);

        ret = pl08x_prep_channel_resources(plchan, txd);
        if (ret)
                return NULL;

        return vchan_tx_prep(&plchan->vc, &txd->vd, flags);
}

static struct dma_async_tx_descriptor *pl08x_prep_slave_sg(
                struct dma_chan *chan, struct scatterlist *sgl,
                unsigned int sg_len, enum dma_transfer_direction direction,
                unsigned long flags, void *context)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
        struct pl08x_driver_data *pl08x = plchan->host;
        struct pl08x_txd *txd;
        struct pl08x_sg *dsg;
        struct scatterlist *sg;
        enum dma_slave_buswidth addr_width;
        dma_addr_t slave_addr;
        int ret, tmp;
        u8 src_buses, dst_buses;
        u32 maxburst, cctl;

        dev_dbg(&pl08x->adev->dev, "%s prepare transaction of %d bytes from %s\n",
                        __func__, sg_dma_len(sgl), plchan->name);

        txd = pl08x_get_txd(plchan);
        if (!txd) {
                dev_err(&pl08x->adev->dev, "%s no txd\n", __func__);
                return NULL;
        }

        /*
         * Set up addresses, the PrimeCell configured address
         * will take precedence since this may configure the
         * channel target address dynamically at runtime.
         */
        if (direction == DMA_MEM_TO_DEV) {
                cctl = PL080_CONTROL_SRC_INCR;
                slave_addr = plchan->cfg.dst_addr;
                addr_width = plchan->cfg.dst_addr_width;
                maxburst = plchan->cfg.dst_maxburst;
                src_buses = pl08x->mem_buses;
                dst_buses = plchan->cd->periph_buses;
        } else if (direction == DMA_DEV_TO_MEM) {
                cctl = PL080_CONTROL_DST_INCR;
                slave_addr = plchan->cfg.src_addr;
                addr_width = plchan->cfg.src_addr_width;
                maxburst = plchan->cfg.src_maxburst;
                src_buses = plchan->cd->periph_buses;
                dst_buses = pl08x->mem_buses;
        } else {
                pl08x_free_txd(pl08x, txd);
                dev_err(&pl08x->adev->dev,
                        "%s direction unsupported\n", __func__);
                return NULL;
        }

        cctl |= pl08x_get_cctl(plchan, addr_width, maxburst);
        if (cctl == ~0) {
                pl08x_free_txd(pl08x, txd);
                dev_err(&pl08x->adev->dev,
                        "DMA slave configuration botched?\n");
                return NULL;
        }

        txd->cctl = cctl | pl08x_select_bus(src_buses, dst_buses);

        if (plchan->cfg.device_fc)
                tmp = (direction == DMA_MEM_TO_DEV) ? PL080_FLOW_MEM2PER_PER :
                        PL080_FLOW_PER2MEM_PER;
        else
                tmp = (direction == DMA_MEM_TO_DEV) ? PL080_FLOW_MEM2PER :
                        PL080_FLOW_PER2MEM;

        txd->ccfg |= tmp << PL080_CONFIG_FLOW_CONTROL_SHIFT;

        ret = pl08x_request_mux(plchan);
        if (ret < 0) {
                pl08x_free_txd(pl08x, txd);
                dev_dbg(&pl08x->adev->dev,
                        "unable to mux for transfer on %s due to platform restrictions\n",
                        plchan->name);
                return NULL;
        }

        dev_dbg(&pl08x->adev->dev, "allocated DMA request signal %d for xfer on %s\n",
                 plchan->signal, plchan->name);

        /* Assign the flow control signal to this channel */
        if (direction == DMA_MEM_TO_DEV)
                txd->ccfg |= plchan->signal << PL080_CONFIG_DST_SEL_SHIFT;
        else
                txd->ccfg |= plchan->signal << PL080_CONFIG_SRC_SEL_SHIFT;

        for_each_sg(sgl, sg, sg_len, tmp) {
                dsg = kzalloc(sizeof(struct pl08x_sg), GFP_NOWAIT);
                if (!dsg) {
                        pl08x_release_mux(plchan);
                        pl08x_free_txd(pl08x, txd);
                        dev_err(&pl08x->adev->dev, "%s no mem for pl080 sg\n",
                                        __func__);
                        return NULL;
                }
                list_add_tail(&dsg->node, &txd->dsg_list);

                dsg->len = sg_dma_len(sg);
                if (direction == DMA_MEM_TO_DEV) {
                        dsg->src_addr = sg_dma_address(sg);
                        dsg->dst_addr = slave_addr;
                } else {
                        dsg->src_addr = slave_addr;
                        dsg->dst_addr = sg_dma_address(sg);
                }
        }

        ret = pl08x_prep_channel_resources(plchan, txd);
        if (ret)
                return NULL;

        return vchan_tx_prep(&plchan->vc, &txd->vd, flags);
}

static int pl08x_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
                         unsigned long arg)
{
        struct pl08x_dma_chan *plchan = to_pl08x_chan(chan);
        struct pl08x_driver_data *pl08x = plchan->host;
        unsigned long flags;
        int ret = 0;

        /* Controls applicable to inactive channels */
        if (cmd == DMA_SLAVE_CONFIG) {
                return dma_set_runtime_config(chan,
                                              (struct dma_slave_config *)arg);
        }

        /*
         * Anything succeeds on channels with no physical allocation and
         * no queued transfers.
         */
        spin_lock_irqsave(&plchan->vc.lock, flags);
        if (!plchan->phychan && !plchan->at) {
                spin_unlock_irqrestore(&plchan->vc.lock, flags);
                return 0;
        }

        switch (cmd) {
        case DMA_TERMINATE_ALL:
                plchan->state = PL08X_CHAN_IDLE;

                if (plchan->phychan) {
                        /*
                         * Mark physical channel as free and free any slave
                         * signal
                         */
                        pl08x_phy_free(plchan);
                }
                /* Dequeue jobs and free LLIs */
                if (plchan->at) {
                        pl08x_desc_free(&plchan->at->vd);
                        plchan->at = NULL;
                }
                /* Dequeue jobs not yet fired as well */
                pl08x_free_txd_list(pl08x, plchan);
                break;
        case DMA_PAUSE:
                pl08x_pause_phy_chan(plchan->phychan);
                plchan->state = PL08X_CHAN_PAUSED;
                break;
        case DMA_RESUME:
                pl08x_resume_phy_chan(plchan->phychan);
                plchan->state = PL08X_CHAN_RUNNING;
                break;
        default:
                /* Unknown command */
                ret = -ENXIO;
                break;
        }

        spin_unlock_irqrestore(&plchan->vc.lock, flags);

        return ret;
}

bool pl08x_filter_id(struct dma_chan *chan, void *chan_id)
{
        struct pl08x_dma_chan *plchan;
        char *name = chan_id;

        /* Reject channels for devices not bound to this driver */
        if (chan->device->dev->driver != &pl08x_amba_driver.drv)
                return false;

        plchan = to_pl08x_chan(chan);

        /* Check that the channel is not taken! */
        if (!strcmp(plchan->name, name))
                return true;

        return false;
}

/*
 * Just check that the device is there and active
 * TODO: turn this bit on/off depending on the number of physical channels
 * actually used, if it is zero... well shut it off. That will save some
 * power. Cut the clock at the same time.
 */
static void pl08x_ensure_on(struct pl08x_driver_data *pl08x)
{
        /* The Nomadik variant does not have the config register */
        if (pl08x->vd->nomadik)
                return;
        writel(PL080_CONFIG_ENABLE, pl08x->base + PL080_CONFIG);
}

static irqreturn_t pl08x_irq(int irq, void *dev)
{
        struct pl08x_driver_data *pl08x = dev;
        u32 mask = 0, err, tc, i;

        /* check & clear - ERR & TC interrupts */
        err = readl(pl08x->base + PL080_ERR_STATUS);
        if (err) {
                dev_err(&pl08x->adev->dev, "%s error interrupt, register value 0x%08x\n",
                        __func__, err);
                writel(err, pl08x->base + PL080_ERR_CLEAR);
        }
        tc = readl(pl08x->base + PL080_TC_STATUS);
        if (tc)
                writel(tc, pl08x->base + PL080_TC_CLEAR);

        if (!err && !tc)
                return IRQ_NONE;

        for (i = 0; i < pl08x->vd->channels; i++) {
                if (((1 << i) & err) || ((1 << i) & tc)) {
                        /* Locate physical channel */
                        struct pl08x_phy_chan *phychan = &pl08x->phy_chans[i];
                        struct pl08x_dma_chan *plchan = phychan->serving;
                        struct pl08x_txd *tx;

                        if (!plchan) {
                                dev_err(&pl08x->adev->dev,
                                        "%s Error TC interrupt on unused channel: 0x%08x\n",
                                        __func__, i);
                                continue;
                        }

                        spin_lock(&plchan->vc.lock);
                        tx = plchan->at;
                        if (tx) {
                                plchan->at = NULL;
                                /*
                                 * This descriptor is done, release its mux
                                 * reservation.
                                 */
                                pl08x_release_mux(plchan);
                                tx->done = true;
                                vchan_cookie_complete(&tx->vd);

                                /*
                                 * And start the next descriptor (if any),
                                 * otherwise free this channel.
                                 */
                                if (vchan_next_desc(&plchan->vc))
                                        pl08x_start_next_txd(plchan);
                                else
                                        pl08x_phy_free(plchan);
                        }
                        spin_unlock(&plchan->vc.lock);

                        mask |= (1 << i);
                }
        }

        return mask ? IRQ_HANDLED : IRQ_NONE;
}

static void pl08x_dma_slave_init(struct pl08x_dma_chan *chan)
{
        chan->slave = true;
        chan->name = chan->cd->bus_id;
        chan->cfg.src_addr = chan->cd->addr;
        chan->cfg.dst_addr = chan->cd->addr;
}

/*
 * Initialise the DMAC memcpy/slave channels.
 * Make a local wrapper to hold required data
 */
static int pl08x_dma_init_virtual_channels(struct pl08x_driver_data *pl08x,
                struct dma_device *dmadev, unsigned int channels, bool slave)
{
        struct pl08x_dma_chan *chan;
        int i;

        INIT_LIST_HEAD(&dmadev->channels);

        /*
         * Register as many many memcpy as we have physical channels,
         * we won't always be able to use all but the code will have
         * to cope with that situation.
         */
        for (i = 0; i < channels; i++) {
                chan = kzalloc(sizeof(*chan), GFP_KERNEL);
                if (!chan) {
                        dev_err(&pl08x->adev->dev,
                                "%s no memory for channel\n", __func__);
                        return -ENOMEM;
                }

                chan->host = pl08x;
                chan->state = PL08X_CHAN_IDLE;
                chan->signal = -1;

                if (slave) {
                        chan->cd = &pl08x->pd->slave_channels[i];
                        pl08x_dma_slave_init(chan);
                } else {
                        chan->cd = &pl08x->pd->memcpy_channel;
                        chan->name = kasprintf(GFP_KERNEL, "memcpy%d", i);
                        if (!chan->name) {
                                kfree(chan);
                                return -ENOMEM;
                        }
                }
                dev_dbg(&pl08x->adev->dev,
                         "initialize virtual channel \"%s\"\n",
                         chan->name);

                chan->vc.desc_free = pl08x_desc_free;
                vchan_init(&chan->vc, dmadev);
        }
        dev_info(&pl08x->adev->dev, "initialized %d virtual %s channels\n",
                 i, slave ? "slave" : "memcpy");
        return i;
}

static void pl08x_free_virtual_channels(struct dma_device *dmadev)
{
        struct pl08x_dma_chan *chan = NULL;
        struct pl08x_dma_chan *next;

        list_for_each_entry_safe(chan,
                                 next, &dmadev->channels, vc.chan.device_node) {
                list_del(&chan->vc.chan.device_node);
                kfree(chan);
        }
}

#ifdef CONFIG_DEBUG_FS
static const char *pl08x_state_str(enum pl08x_dma_chan_state state)
{
        switch (state) {
        case PL08X_CHAN_IDLE:
                return "idle";
        case PL08X_CHAN_RUNNING:
                return "running";
        case PL08X_CHAN_PAUSED:
                return "paused";
        case PL08X_CHAN_WAITING:
                return "waiting";
        default:
                break;
        }
        return "UNKNOWN STATE";
}

static int pl08x_debugfs_show(struct seq_file *s, void *data)
{
        struct pl08x_driver_data *pl08x = s->private;
        struct pl08x_dma_chan *chan;
        struct pl08x_phy_chan *ch;
        unsigned long flags;
        int i;

        seq_printf(s, "PL08x physical channels:\n");
        seq_printf(s, "CHANNEL:\tUSER:\n");
        seq_printf(s, "--------\t-----\n");
        for (i = 0; i < pl08x->vd->channels; i++) {
                struct pl08x_dma_chan *virt_chan;

                ch = &pl08x->phy_chans[i];

                spin_lock_irqsave(&ch->lock, flags);
                virt_chan = ch->serving;

                seq_printf(s, "%d\t\t%s%s\n",
                           ch->id,
                           virt_chan ? virt_chan->name : "(none)",
                           ch->locked ? " LOCKED" : "");

                spin_unlock_irqrestore(&ch->lock, flags);
        }

        seq_printf(s, "\nPL08x virtual memcpy channels:\n");
        seq_printf(s, "CHANNEL:\tSTATE:\n");
        seq_printf(s, "--------\t------\n");
        list_for_each_entry(chan, &pl08x->memcpy.channels, vc.chan.device_node) {
                seq_printf(s, "%s\t\t%s\n", chan->name,
                           pl08x_state_str(chan->state));
        }

        seq_printf(s, "\nPL08x virtual slave channels:\n");
        seq_printf(s, "CHANNEL:\tSTATE:\n");
        seq_printf(s, "--------\t------\n");
        list_for_each_entry(chan, &pl08x->slave.channels, vc.chan.device_node) {
                seq_printf(s, "%s\t\t%s\n", chan->name,
                           pl08x_state_str(chan->state));
        }

        return 0;
}

static int pl08x_debugfs_open(struct inode *inode, struct file *file)
{
        return single_open(file, pl08x_debugfs_show, inode->i_private);
}

static const struct file_operations pl08x_debugfs_operations = {
        .open           = pl08x_debugfs_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static void init_pl08x_debugfs(struct pl08x_driver_data *pl08x)
{
        /* Expose a simple debugfs interface to view all clocks */
        (void) debugfs_create_file(dev_name(&pl08x->adev->dev),
                        S_IFREG | S_IRUGO, NULL, pl08x,
                        &pl08x_debugfs_operations);
}

#else
static inline void init_pl08x_debugfs(struct pl08x_driver_data *pl08x)
{
}
#endif

static int pl08x_probe(struct amba_device *adev, const struct amba_id *id)
{
        struct pl08x_driver_data *pl08x;
        const struct vendor_data *vd = id->data;
        int ret = 0;
        int i;

        ret = amba_request_regions(adev, NULL);
        if (ret)
                return ret;

        /* Create the driver state holder */
        pl08x = kzalloc(sizeof(*pl08x), GFP_KERNEL);
        if (!pl08x) {
                ret = -ENOMEM;
                goto out_no_pl08x;
        }

        /* Initialize memcpy engine */
        dma_cap_set(DMA_MEMCPY, pl08x->memcpy.cap_mask);
        pl08x->memcpy.dev = &adev->dev;
        pl08x->memcpy.device_alloc_chan_resources = pl08x_alloc_chan_resources;
        pl08x->memcpy.device_free_chan_resources = pl08x_free_chan_resources;
        pl08x->memcpy.device_prep_dma_memcpy = pl08x_prep_dma_memcpy;
        pl08x->memcpy.device_prep_dma_interrupt = pl08x_prep_dma_interrupt;
        pl08x->memcpy.device_tx_status = pl08x_dma_tx_status;
        pl08x->memcpy.device_issue_pending = pl08x_issue_pending;
        pl08x->memcpy.device_control = pl08x_control;

        /* Initialize slave engine */
        dma_cap_set(DMA_SLAVE, pl08x->slave.cap_mask);
        pl08x->slave.dev = &adev->dev;
        pl08x->slave.device_alloc_chan_resources = pl08x_alloc_chan_resources;
        pl08x->slave.device_free_chan_resources = pl08x_free_chan_resources;
        pl08x->slave.device_prep_dma_interrupt = pl08x_prep_dma_interrupt;
        pl08x->slave.device_tx_status = pl08x_dma_tx_status;
        pl08x->slave.device_issue_pending = pl08x_issue_pending;
        pl08x->slave.device_prep_slave_sg = pl08x_prep_slave_sg;
        pl08x->slave.device_control = pl08x_control;

        /* Get the platform data */
        pl08x->pd = dev_get_platdata(&adev->dev);
        if (!pl08x->pd) {
                dev_err(&adev->dev, "no platform data supplied\n");
                goto out_no_platdata;
        }

        /* Assign useful pointers to the driver state */
        pl08x->adev = adev;
        pl08x->vd = vd;

        /* By default, AHB1 only.  If dualmaster, from platform */
        pl08x->lli_buses = PL08X_AHB1;
        pl08x->mem_buses = PL08X_AHB1;
        if (pl08x->vd->dualmaster) {
                pl08x->lli_buses = pl08x->pd->lli_buses;
                pl08x->mem_buses = pl08x->pd->mem_buses;
        }

        /* A DMA memory pool for LLIs, align on 1-byte boundary */
        pl08x->pool = dma_pool_create(DRIVER_NAME, &pl08x->adev->dev,
                        PL08X_LLI_TSFR_SIZE, PL08X_ALIGN, 0);
        if (!pl08x->pool) {
                ret = -ENOMEM;
                goto out_no_lli_pool;
        }

        pl08x->base = ioremap(adev->res.start, resource_size(&adev->res));
        if (!pl08x->base) {
                ret = -ENOMEM;
                goto out_no_ioremap;
        }

        /* Turn on the PL08x */
        pl08x_ensure_on(pl08x);

        /* Attach the interrupt handler */
        writel(0x000000FF, pl08x->base + PL080_ERR_CLEAR);
        writel(0x000000FF, pl08x->base + PL080_TC_CLEAR);

        ret = request_irq(adev->irq[0], pl08x_irq, IRQF_DISABLED,
                          DRIVER_NAME, pl08x);
        if (ret) {
                dev_err(&adev->dev, "%s failed to request interrupt %d\n",
                        __func__, adev->irq[0]);
                goto out_no_irq;
        }

        /* Initialize physical channels */
        pl08x->phy_chans = kzalloc((vd->channels * sizeof(*pl08x->phy_chans)),
                        GFP_KERNEL);
        if (!pl08x->phy_chans) {
                dev_err(&adev->dev, "%s failed to allocate "
                        "physical channel holders\n",
                        __func__);
                goto out_no_phychans;
        }

        for (i = 0; i < vd->channels; i++) {
                struct pl08x_phy_chan *ch = &pl08x->phy_chans[i];

                ch->id = i;
                ch->base = pl08x->base + PL080_Cx_BASE(i);
                spin_lock_init(&ch->lock);

                /*
                 * Nomadik variants can have channels that are locked
                 * down for the secure world only. Lock up these channels
                 * by perpetually serving a dummy virtual channel.
                 */
                if (vd->nomadik) {
                        u32 val;

                        val = readl(ch->base + PL080_CH_CONFIG);
                        if (val & (PL080N_CONFIG_ITPROT | PL080N_CONFIG_SECPROT)) {
                                dev_info(&adev->dev, "physical channel %d reserved for secure access only\n", i);
                                ch->locked = true;
                        }
                }

                dev_dbg(&adev->dev, "physical channel %d is %s\n",
                        i, pl08x_phy_channel_busy(ch) ? "BUSY" : "FREE");
        }

        /* Register as many memcpy channels as there are physical channels */
        ret = pl08x_dma_init_virtual_channels(pl08x, &pl08x->memcpy,
                                              pl08x->vd->channels, false);
        if (ret <= 0) {
                dev_warn(&pl08x->adev->dev,
                         "%s failed to enumerate memcpy channels - %d\n",
                         __func__, ret);
                goto out_no_memcpy;
        }
        pl08x->memcpy.chancnt = ret;

        /* Register slave channels */
        ret = pl08x_dma_init_virtual_channels(pl08x, &pl08x->slave,
                        pl08x->pd->num_slave_channels, true);
        if (ret <= 0) {
                dev_warn(&pl08x->adev->dev,
                        "%s failed to enumerate slave channels - %d\n",
                                __func__, ret);
                goto out_no_slave;
        }
        pl08x->slave.chancnt = ret;

        ret = dma_async_device_register(&pl08x->memcpy);
        if (ret) {
                dev_warn(&pl08x->adev->dev,
                        "%s failed to register memcpy as an async device - %d\n",
                        __func__, ret);
                goto out_no_memcpy_reg;
        }

        ret = dma_async_device_register(&pl08x->slave);
        if (ret) {
                dev_warn(&pl08x->adev->dev,
                        "%s failed to register slave as an async device - %d\n",
                        __func__, ret);
                goto out_no_slave_reg;
        }

        amba_set_drvdata(adev, pl08x);
        init_pl08x_debugfs(pl08x);
        dev_info(&pl08x->adev->dev, "DMA: PL%03x rev%u at 0x%08llx irq %d\n",
                 amba_part(adev), amba_rev(adev),
                 (unsigned long long)adev->res.start, adev->irq[0]);

        return 0;

out_no_slave_reg:
        dma_async_device_unregister(&pl08x->memcpy);
out_no_memcpy_reg:
        pl08x_free_virtual_channels(&pl08x->slave);
out_no_slave:
        pl08x_free_virtual_channels(&pl08x->memcpy);
out_no_memcpy:
        kfree(pl08x->phy_chans);
out_no_phychans:
        free_irq(adev->irq[0], pl08x);
out_no_irq:
        iounmap(pl08x->base);
out_no_ioremap:
        dma_pool_destroy(pl08x->pool);
out_no_lli_pool:
out_no_platdata:
        kfree(pl08x);
out_no_pl08x:
        amba_release_regions(adev);
        return ret;
}

/* PL080 has 8 channels and the PL080 have just 2 */
static struct vendor_data vendor_pl080 = {
        .channels = 8,
        .dualmaster = true,
};

static struct vendor_data vendor_nomadik = {
        .channels = 8,
        .dualmaster = true,
        .nomadik = true,
};

static struct vendor_data vendor_pl081 = {
        .channels = 2,
        .dualmaster = false,
};

static struct amba_id pl08x_ids[] = {
        /* PL080 */
        {
                .id     = 0x00041080,
                .mask   = 0x000fffff,
                .data   = &vendor_pl080,
        },
        /* PL081 */
        {
                .id     = 0x00041081,
                .mask   = 0x000fffff,
                .data   = &vendor_pl081,
        },
        /* Nomadik 8815 PL080 variant */
        {
                .id     = 0x00280080,
                .mask   = 0x00ffffff,
                .data   = &vendor_nomadik,
        },
        { 0, 0 },
};

MODULE_DEVICE_TABLE(amba, pl08x_ids);

static struct amba_driver pl08x_amba_driver = {
        .drv.name       = DRIVER_NAME,
        .id_table       = pl08x_ids,
        .probe          = pl08x_probe,
};

static int __init pl08x_init(void)
{
        int retval;
        retval = amba_driver_register(&pl08x_amba_driver);
        if (retval)
                printk(KERN_WARNING DRIVER_NAME
                       "failed to register as an AMBA device (%d)\n",
                       retval);
        return retval;
}
subsys_initcall(pl08x_init);