[PATCH] cciss: direct lookup for command completions

[deliverable/linux.git] / drivers / block / cciss_scsi.c

/*
 *    Disk Array driver for Compaq SA53xx Controllers, SCSI Tape module
 *    Copyright 2001 Compaq Computer Corporation
 *
 *    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, GOOD TITLE or
 *    NON INFRINGEMENT.  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *    Questions/Comments/Bugfixes to iss_storagedev@hp.com
 *    
 *    Author: Stephen M. Cameron
 */
#ifdef CONFIG_CISS_SCSI_TAPE

/* Here we have code to present the driver as a scsi driver 
   as it is simultaneously presented as a block driver.  The 
   reason for doing this is to allow access to SCSI tape drives
   through the array controller.  Note in particular, neither 
   physical nor logical disks are presented through the scsi layer. */

#include <scsi/scsi.h> 
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h> 
#include <asm/atomic.h>
#include <linux/timer.h>
#include <linux/completion.h>

#include "cciss_scsi.h"

/* some prototypes... */ 
static int sendcmd(
        __u8    cmd,
        int     ctlr,
        void    *buff,
        size_t  size,
        unsigned int use_unit_num, /* 0: address the controller,
                                      1: address logical volume log_unit, 
                                      2: address is in scsi3addr */
        unsigned int log_unit,
        __u8    page_code,
        unsigned char *scsi3addr,
        int cmd_type);


static int cciss_scsi_proc_info(
                struct Scsi_Host *sh,
                char *buffer, /* data buffer */
                char **start,      /* where data in buffer starts */
                off_t offset,      /* offset from start of imaginary file */
                int length,        /* length of data in buffer */
                int func);         /* 0 == read, 1 == write */

static int cciss_scsi_queue_command (struct scsi_cmnd *cmd,
                void (* done)(struct scsi_cmnd *));

static struct cciss_scsi_hba_t ccissscsi[MAX_CTLR] = {
        { .name = "cciss0", .ndevices = 0 },
        { .name = "cciss1", .ndevices = 0 },
        { .name = "cciss2", .ndevices = 0 },
        { .name = "cciss3", .ndevices = 0 },
        { .name = "cciss4", .ndevices = 0 },
        { .name = "cciss5", .ndevices = 0 },
        { .name = "cciss6", .ndevices = 0 },
        { .name = "cciss7", .ndevices = 0 },
};

static struct scsi_host_template cciss_driver_template = {
        .module                 = THIS_MODULE,
        .name                   = "cciss",
        .proc_name              = "cciss",
        .proc_info              = cciss_scsi_proc_info,
        .queuecommand           = cciss_scsi_queue_command,
        .can_queue              = SCSI_CCISS_CAN_QUEUE,
        .this_id                = 7,
        .sg_tablesize           = MAXSGENTRIES,
        .cmd_per_lun            = 1,
        .use_clustering         = DISABLE_CLUSTERING,
};

#pragma pack(1)
struct cciss_scsi_cmd_stack_elem_t {
        CommandList_struct cmd;
        ErrorInfo_struct Err;
        __u32 busaddr;
        __u32 pad;
};

#pragma pack()

#define CMD_STACK_SIZE (SCSI_CCISS_CAN_QUEUE * \
                CCISS_MAX_SCSI_DEVS_PER_HBA + 2)
                        // plus two for init time usage

#pragma pack(1)
struct cciss_scsi_cmd_stack_t {
        struct cciss_scsi_cmd_stack_elem_t *pool;
        struct cciss_scsi_cmd_stack_elem_t *elem[CMD_STACK_SIZE];
        dma_addr_t cmd_pool_handle;
        int top;
};
#pragma pack()

struct cciss_scsi_adapter_data_t {
        struct Scsi_Host *scsi_host;
        struct cciss_scsi_cmd_stack_t cmd_stack;
        int registered;
        spinlock_t lock; // to protect ccissscsi[ctlr]; 
};

#define CPQ_TAPE_LOCK(ctlr, flags) spin_lock_irqsave( \
        &(((struct cciss_scsi_adapter_data_t *) \
        hba[ctlr]->scsi_ctlr)->lock), flags);
#define CPQ_TAPE_UNLOCK(ctlr, flags) spin_unlock_irqrestore( \
        &(((struct cciss_scsi_adapter_data_t *) \
        hba[ctlr]->scsi_ctlr)->lock), flags);

static CommandList_struct *
scsi_cmd_alloc(ctlr_info_t *h)
{
        /* assume only one process in here at a time, locking done by caller. */
        /* use CCISS_LOCK(ctlr) */
        /* might be better to rewrite how we allocate scsi commands in a way that */
        /* needs no locking at all. */

        /* take the top memory chunk off the stack and return it, if any. */
        struct cciss_scsi_cmd_stack_elem_t *c;
        struct cciss_scsi_adapter_data_t *sa;
        struct cciss_scsi_cmd_stack_t *stk;
        u64bit temp64;

        sa = (struct cciss_scsi_adapter_data_t *) h->scsi_ctlr;
        stk = &sa->cmd_stack; 

        if (stk->top < 0) 
                return NULL;
        c = stk->elem[stk->top];        
        /* memset(c, 0, sizeof(*c)); */
        memset(&c->cmd, 0, sizeof(c->cmd));
        memset(&c->Err, 0, sizeof(c->Err));
        /* set physical addr of cmd and addr of scsi parameters */
        c->cmd.busaddr = c->busaddr; 
        /* (__u32) (stk->cmd_pool_handle + 
                (sizeof(struct cciss_scsi_cmd_stack_elem_t)*stk->top)); */

        temp64.val = (__u64) (c->busaddr + sizeof(CommandList_struct));
        /* (__u64) (stk->cmd_pool_handle + 
                (sizeof(struct cciss_scsi_cmd_stack_elem_t)*stk->top) +
                 sizeof(CommandList_struct)); */
        stk->top--;
        c->cmd.ErrDesc.Addr.lower = temp64.val32.lower;
        c->cmd.ErrDesc.Addr.upper = temp64.val32.upper;
        c->cmd.ErrDesc.Len = sizeof(ErrorInfo_struct);
        
        c->cmd.ctlr = h->ctlr;
        c->cmd.err_info = &c->Err;

        return (CommandList_struct *) c;
}

static void 
scsi_cmd_free(ctlr_info_t *h, CommandList_struct *cmd)
{
        /* assume only one process in here at a time, locking done by caller. */
        /* use CCISS_LOCK(ctlr) */
        /* drop the free memory chunk on top of the stack. */

        struct cciss_scsi_adapter_data_t *sa;
        struct cciss_scsi_cmd_stack_t *stk;

        sa = (struct cciss_scsi_adapter_data_t *) h->scsi_ctlr;
        stk = &sa->cmd_stack; 
        if (stk->top >= CMD_STACK_SIZE) {
                printk("cciss: scsi_cmd_free called too many times.\n");
                BUG();
        }
        stk->top++;
        stk->elem[stk->top] = (struct cciss_scsi_cmd_stack_elem_t *) cmd;
}

static int
scsi_cmd_stack_setup(int ctlr, struct cciss_scsi_adapter_data_t *sa)
{
        int i;
        struct cciss_scsi_cmd_stack_t *stk;
        size_t size;

        stk = &sa->cmd_stack; 
        size = sizeof(struct cciss_scsi_cmd_stack_elem_t) * CMD_STACK_SIZE;

        // pci_alloc_consistent guarantees 32-bit DMA address will
        // be used

        stk->pool = (struct cciss_scsi_cmd_stack_elem_t *)
                pci_alloc_consistent(hba[ctlr]->pdev, size, &stk->cmd_pool_handle);

        if (stk->pool == NULL) {
                printk("stk->pool is null\n");
                return -1;
        }

        for (i=0; i<CMD_STACK_SIZE; i++) {
                stk->elem[i] = &stk->pool[i];
                stk->elem[i]->busaddr = (__u32) (stk->cmd_pool_handle + 
                        (sizeof(struct cciss_scsi_cmd_stack_elem_t) * i));
        }
        stk->top = CMD_STACK_SIZE-1;
        return 0;
}

static void
scsi_cmd_stack_free(int ctlr)
{
        struct cciss_scsi_adapter_data_t *sa;
        struct cciss_scsi_cmd_stack_t *stk;
        size_t size;

        sa = (struct cciss_scsi_adapter_data_t *) hba[ctlr]->scsi_ctlr;
        stk = &sa->cmd_stack; 
        if (stk->top != CMD_STACK_SIZE-1) {
                printk( "cciss: %d scsi commands are still outstanding.\n",
                        CMD_STACK_SIZE - stk->top);
                // BUG();
                printk("WE HAVE A BUG HERE!!! stk=0x%p\n", stk);
        }
        size = sizeof(struct cciss_scsi_cmd_stack_elem_t) * CMD_STACK_SIZE;

        pci_free_consistent(hba[ctlr]->pdev, size, stk->pool, stk->cmd_pool_handle);
        stk->pool = NULL;
}

/* scsi_device_types comes from scsi.h */
#define DEVICETYPE(n) (n<0 || n>MAX_SCSI_DEVICE_CODE) ? \
        "Unknown" : scsi_device_types[n]

#if 0
static int xmargin=8;
static int amargin=60;

static void
print_bytes (unsigned char *c, int len, int hex, int ascii)
{

        int i;
        unsigned char *x;

        if (hex)
        {
                x = c;
                for (i=0;i<len;i++)
                {
                        if ((i % xmargin) == 0 && i>0) printk("\n");
                        if ((i % xmargin) == 0) printk("0x%04x:", i);
                        printk(" %02x", *x);
                        x++;
                }
                printk("\n");
        }
        if (ascii)
        {
                x = c;
                for (i=0;i<len;i++)
                {
                        if ((i % amargin) == 0 && i>0) printk("\n");
                        if ((i % amargin) == 0) printk("0x%04x:", i);
                        if (*x > 26 && *x < 128) printk("%c", *x);
                        else printk(".");
                        x++;
                }
                printk("\n");
        }
}

static void
print_cmd(CommandList_struct *cp)
{
        printk("queue:%d\n", cp->Header.ReplyQueue);
        printk("sglist:%d\n", cp->Header.SGList);
        printk("sgtot:%d\n", cp->Header.SGTotal);
        printk("Tag:0x%08x/0x%08x\n", cp->Header.Tag.upper, 
                        cp->Header.Tag.lower);
        printk("LUN:0x%02x%02x%02x%02x%02x%02x%02x%02x\n",
                cp->Header.LUN.LunAddrBytes[0],
                cp->Header.LUN.LunAddrBytes[1],
                cp->Header.LUN.LunAddrBytes[2],
                cp->Header.LUN.LunAddrBytes[3],
                cp->Header.LUN.LunAddrBytes[4],
                cp->Header.LUN.LunAddrBytes[5],
                cp->Header.LUN.LunAddrBytes[6],
                cp->Header.LUN.LunAddrBytes[7]);
        printk("CDBLen:%d\n", cp->Request.CDBLen);
        printk("Type:%d\n",cp->Request.Type.Type);
        printk("Attr:%d\n",cp->Request.Type.Attribute);
        printk(" Dir:%d\n",cp->Request.Type.Direction);
        printk("Timeout:%d\n",cp->Request.Timeout);
        printk( "CDB: %02x %02x %02x %02x %02x %02x %02x %02x"
                " %02x %02x %02x %02x %02x %02x %02x %02x\n",
                cp->Request.CDB[0], cp->Request.CDB[1],
                cp->Request.CDB[2], cp->Request.CDB[3],
                cp->Request.CDB[4], cp->Request.CDB[5],
                cp->Request.CDB[6], cp->Request.CDB[7],
                cp->Request.CDB[8], cp->Request.CDB[9],
                cp->Request.CDB[10], cp->Request.CDB[11],
                cp->Request.CDB[12], cp->Request.CDB[13],
                cp->Request.CDB[14], cp->Request.CDB[15]),
        printk("edesc.Addr: 0x%08x/0%08x, Len  = %d\n", 
                cp->ErrDesc.Addr.upper, cp->ErrDesc.Addr.lower, 
                        cp->ErrDesc.Len);
        printk("sgs..........Errorinfo:\n");
        printk("scsistatus:%d\n", cp->err_info->ScsiStatus);
        printk("senselen:%d\n", cp->err_info->SenseLen);
        printk("cmd status:%d\n", cp->err_info->CommandStatus);
        printk("resid cnt:%d\n", cp->err_info->ResidualCnt);
        printk("offense size:%d\n", cp->err_info->MoreErrInfo.Invalid_Cmd.offense_size);
        printk("offense byte:%d\n", cp->err_info->MoreErrInfo.Invalid_Cmd.offense_num);
        printk("offense value:%d\n", cp->err_info->MoreErrInfo.Invalid_Cmd.offense_value);
                        
}

#endif

static int 
find_bus_target_lun(int ctlr, int *bus, int *target, int *lun)
{
        /* finds an unused bus, target, lun for a new device */
        /* assumes hba[ctlr]->scsi_ctlr->lock is held */ 
        int i, found=0;
        unsigned char target_taken[CCISS_MAX_SCSI_DEVS_PER_HBA];

        memset(&target_taken[0], 0, CCISS_MAX_SCSI_DEVS_PER_HBA);

        target_taken[SELF_SCSI_ID] = 1; 
        for (i=0;i<ccissscsi[ctlr].ndevices;i++)
                target_taken[ccissscsi[ctlr].dev[i].target] = 1;
        
        for (i=0;i<CCISS_MAX_SCSI_DEVS_PER_HBA;i++) {
                if (!target_taken[i]) {
                        *bus = 0; *target=i; *lun = 0; found=1;
                        break;
                }
        }
        return (!found);        
}

static int 
cciss_scsi_add_entry(int ctlr, int hostno, 
                unsigned char *scsi3addr, int devtype)
{
        /* assumes hba[ctlr]->scsi_ctlr->lock is held */ 
        int n = ccissscsi[ctlr].ndevices;
        struct cciss_scsi_dev_t *sd;

        if (n >= CCISS_MAX_SCSI_DEVS_PER_HBA) {
                printk("cciss%d: Too many devices, "
                        "some will be inaccessible.\n", ctlr);
                return -1;
        }
        sd = &ccissscsi[ctlr].dev[n];
        if (find_bus_target_lun(ctlr, &sd->bus, &sd->target, &sd->lun) != 0)
                return -1;
        memcpy(&sd->scsi3addr[0], scsi3addr, 8);
        sd->devtype = devtype;
        ccissscsi[ctlr].ndevices++;

        /* initially, (before registering with scsi layer) we don't 
           know our hostno and we don't want to print anything first 
           time anyway (the scsi layer's inquiries will show that info) */
        if (hostno != -1)
                printk("cciss%d: %s device c%db%dt%dl%d added.\n", 
                        ctlr, DEVICETYPE(sd->devtype), hostno, 
                        sd->bus, sd->target, sd->lun);
        return 0;
}

static void
cciss_scsi_remove_entry(int ctlr, int hostno, int entry)
{
        /* assumes hba[ctlr]->scsi_ctlr->lock is held */ 
        int i;
        struct cciss_scsi_dev_t sd;

        if (entry < 0 || entry >= CCISS_MAX_SCSI_DEVS_PER_HBA) return;
        sd = ccissscsi[ctlr].dev[entry];
        for (i=entry;i<ccissscsi[ctlr].ndevices-1;i++)
                ccissscsi[ctlr].dev[i] = ccissscsi[ctlr].dev[i+1];
        ccissscsi[ctlr].ndevices--;
        printk("cciss%d: %s device c%db%dt%dl%d removed.\n",
                ctlr, DEVICETYPE(sd.devtype), hostno, 
                        sd.bus, sd.target, sd.lun);
}


#define SCSI3ADDR_EQ(a,b) ( \
        (a)[7] == (b)[7] && \
        (a)[6] == (b)[6] && \
        (a)[5] == (b)[5] && \
        (a)[4] == (b)[4] && \
        (a)[3] == (b)[3] && \
        (a)[2] == (b)[2] && \
        (a)[1] == (b)[1] && \
        (a)[0] == (b)[0])

static int
adjust_cciss_scsi_table(int ctlr, int hostno,
        struct cciss_scsi_dev_t sd[], int nsds)
{
        /* sd contains scsi3 addresses and devtypes, but
           bus target and lun are not filled in.  This funciton
           takes what's in sd to be the current and adjusts
           ccissscsi[] to be in line with what's in sd. */ 

        int i,j, found, changes=0;
        struct cciss_scsi_dev_t *csd;
        unsigned long flags;

        CPQ_TAPE_LOCK(ctlr, flags);

        /* find any devices in ccissscsi[] that are not in 
           sd[] and remove them from ccissscsi[] */

        i = 0;
        while(i<ccissscsi[ctlr].ndevices) {
                csd = &ccissscsi[ctlr].dev[i];
                found=0;
                for (j=0;j<nsds;j++) {
                        if (SCSI3ADDR_EQ(sd[j].scsi3addr,
                                csd->scsi3addr)) {
                                if (sd[j].devtype == csd->devtype)
                                        found=2;
                                else
                                        found=1;
                                break;
                        }
                }

                if (found == 0) { /* device no longer present. */ 
                        changes++;
                        /* printk("cciss%d: %s device c%db%dt%dl%d removed.\n",
                                ctlr, DEVICETYPE(csd->devtype), hostno, 
                                        csd->bus, csd->target, csd->lun); */
                        cciss_scsi_remove_entry(ctlr, hostno, i);
                        /* note, i not incremented */
                } 
                else if (found == 1) { /* device is different kind */
                        changes++;
                        printk("cciss%d: device c%db%dt%dl%d type changed "
                                "(device type now %s).\n",
                                ctlr, hostno, csd->bus, csd->target, csd->lun,
                                        DEVICETYPE(csd->devtype));
                        csd->devtype = sd[j].devtype;
                        i++;    /* so just move along. */
                } else          /* device is same as it ever was, */
                        i++;    /* so just move along. */
        }

        /* Now, make sure every device listed in sd[] is also
           listed in ccissscsi[], adding them if they aren't found */

        for (i=0;i<nsds;i++) {
                found=0;
                for (j=0;j<ccissscsi[ctlr].ndevices;j++) {
                        csd = &ccissscsi[ctlr].dev[j];
                        if (SCSI3ADDR_EQ(sd[i].scsi3addr,
                                csd->scsi3addr)) {
                                if (sd[i].devtype == csd->devtype)
                                        found=2;        /* found device */
                                else
                                        found=1;        /* found a bug. */
                                break;
                        }
                }
                if (!found) {
                        changes++;
                        if (cciss_scsi_add_entry(ctlr, hostno, 
                                &sd[i].scsi3addr[0], sd[i].devtype) != 0)
                                break;
                } else if (found == 1) {
                        /* should never happen... */
                        changes++;
                        printk("cciss%d: device unexpectedly changed type\n",
                                ctlr);
                        /* but if it does happen, we just ignore that device */
                }
        }
        CPQ_TAPE_UNLOCK(ctlr, flags);

        if (!changes) 
                printk("cciss%d: No device changes detected.\n", ctlr);

        return 0;
}

static int
lookup_scsi3addr(int ctlr, int bus, int target, int lun, char *scsi3addr)
{
        int i;
        struct cciss_scsi_dev_t *sd;
        unsigned long flags;

        CPQ_TAPE_LOCK(ctlr, flags);
        for (i=0;i<ccissscsi[ctlr].ndevices;i++) {
                sd = &ccissscsi[ctlr].dev[i];
                if (sd->bus == bus &&
                    sd->target == target &&
                    sd->lun == lun) {
                        memcpy(scsi3addr, &sd->scsi3addr[0], 8);
                        CPQ_TAPE_UNLOCK(ctlr, flags);
                        return 0;
                }
        }
        CPQ_TAPE_UNLOCK(ctlr, flags);
        return -1;
}

static void 
cciss_scsi_setup(int cntl_num)
{
        struct cciss_scsi_adapter_data_t * shba;

        ccissscsi[cntl_num].ndevices = 0;
        shba = (struct cciss_scsi_adapter_data_t *)
                kmalloc(sizeof(*shba), GFP_KERNEL);     
        if (shba == NULL)
                return;
        shba->scsi_host = NULL;
        spin_lock_init(&shba->lock);
        shba->registered = 0;
        if (scsi_cmd_stack_setup(cntl_num, shba) != 0) {
                kfree(shba);
                shba = NULL;
        }
        hba[cntl_num]->scsi_ctlr = (void *) shba;
        return;
}

static void
complete_scsi_command( CommandList_struct *cp, int timeout, __u32 tag)
{
        struct scsi_cmnd *cmd;
        ctlr_info_t *ctlr;
        u64bit addr64;
        ErrorInfo_struct *ei;

        ei = cp->err_info;

        /* First, see if it was a message rather than a command */
        if (cp->Request.Type.Type == TYPE_MSG)  {
                cp->cmd_type = CMD_MSG_DONE;
                return;
        }

        cmd = (struct scsi_cmnd *) cp->scsi_cmd;        
        ctlr = hba[cp->ctlr];

        /* undo the DMA mappings */

        if (cmd->use_sg) {
                pci_unmap_sg(ctlr->pdev,
                        cmd->buffer, cmd->use_sg,
                                cmd->sc_data_direction); 
        }
        else if (cmd->request_bufflen) {
                addr64.val32.lower = cp->SG[0].Addr.lower;
                addr64.val32.upper = cp->SG[0].Addr.upper;
                pci_unmap_single(ctlr->pdev, (dma_addr_t) addr64.val,
                        cmd->request_bufflen, 
                                cmd->sc_data_direction);
        }

        cmd->result = (DID_OK << 16);           /* host byte */
        cmd->result |= (COMMAND_COMPLETE << 8); /* msg byte */
        /* cmd->result |= (GOOD < 1); */                /* status byte */

        cmd->result |= (ei->ScsiStatus);
        /* printk("Scsistatus is 0x%02x\n", ei->ScsiStatus);  */

        /* copy the sense data whether we need to or not. */

        memcpy(cmd->sense_buffer, ei->SenseInfo, 
                ei->SenseLen > SCSI_SENSE_BUFFERSIZE ?
                        SCSI_SENSE_BUFFERSIZE : 
                        ei->SenseLen);
        cmd->resid = ei->ResidualCnt;

        if(ei->CommandStatus != 0) 
        { /* an error has occurred */ 
                switch(ei->CommandStatus)
                {
                        case CMD_TARGET_STATUS:
                                /* Pass it up to the upper layers... */
                                if( ei->ScsiStatus)
                                {
#if 0
                                        printk(KERN_WARNING "cciss: cmd %p "
                                        "has SCSI Status = %x\n",
                                                cp,  
                                                ei->ScsiStatus); 
#endif
                                        cmd->result |= (ei->ScsiStatus < 1);
                                }
                                else {  /* scsi status is zero??? How??? */
                                        
        /* Ordinarily, this case should never happen, but there is a bug
           in some released firmware revisions that allows it to happen
           if, for example, a 4100 backplane loses power and the tape
           drive is in it.  We assume that it's a fatal error of some
           kind because we can't show that it wasn't. We will make it
           look like selection timeout since that is the most common
           reason for this to occur, and it's severe enough. */

                                        cmd->result = DID_NO_CONNECT << 16;
                                }
                        break;
                        case CMD_DATA_UNDERRUN: /* let mid layer handle it. */
                        break;
                        case CMD_DATA_OVERRUN:
                                printk(KERN_WARNING "cciss: cp %p has"
                                        " completed with data overrun "
                                        "reported\n", cp);
                        break;
                        case CMD_INVALID: {
                                /* print_bytes(cp, sizeof(*cp), 1, 0);
                                print_cmd(cp); */
     /* We get CMD_INVALID if you address a non-existent tape drive instead
        of a selection timeout (no response).  You will see this if you yank 
        out a tape drive, then try to access it. This is kind of a shame
        because it means that any other CMD_INVALID (e.g. driver bug) will
        get interpreted as a missing target. */
                                cmd->result = DID_NO_CONNECT << 16;
                                }
                        break;
                        case CMD_PROTOCOL_ERR:
                                printk(KERN_WARNING "cciss: cp %p has "
                                        "protocol error \n", cp);
                        break;
                        case CMD_HARDWARE_ERR:
                                cmd->result = DID_ERROR << 16;
                                printk(KERN_WARNING "cciss: cp %p had " 
                                        " hardware error\n", cp);
                        break;
                        case CMD_CONNECTION_LOST:
                                cmd->result = DID_ERROR << 16;
                                printk(KERN_WARNING "cciss: cp %p had "
                                        "connection lost\n", cp);
                        break;
                        case CMD_ABORTED:
                                cmd->result = DID_ABORT << 16;
                                printk(KERN_WARNING "cciss: cp %p was "
                                        "aborted\n", cp);
                        break;
                        case CMD_ABORT_FAILED:
                                cmd->result = DID_ERROR << 16;
                                printk(KERN_WARNING "cciss: cp %p reports "
                                        "abort failed\n", cp);
                        break;
                        case CMD_UNSOLICITED_ABORT:
                                cmd->result = DID_ABORT << 16;
                                printk(KERN_WARNING "cciss: cp %p aborted "
                                        "do to an unsolicited abort\n", cp);
                        break;
                        case CMD_TIMEOUT:
                                cmd->result = DID_TIME_OUT << 16;
                                printk(KERN_WARNING "cciss: cp %p timedout\n",
                                        cp);
                        break;
                        default:
                                cmd->result = DID_ERROR << 16;
                                printk(KERN_WARNING "cciss: cp %p returned "
                                        "unknown status %x\n", cp, 
                                                ei->CommandStatus); 
                }
        }
        // printk("c:%p:c%db%dt%dl%d ", cmd, ctlr->ctlr, cmd->channel, 
        //      cmd->target, cmd->lun);
        cmd->scsi_done(cmd);
        scsi_cmd_free(ctlr, cp);
}

static int
cciss_scsi_detect(int ctlr)
{
        struct Scsi_Host *sh;
        int error;

        sh = scsi_host_alloc(&cciss_driver_template, sizeof(struct ctlr_info *));
        if (sh == NULL)
                goto fail;
        sh->io_port = 0;        // good enough?  FIXME, 
        sh->n_io_port = 0;      // I don't think we use these two...
        sh->this_id = SELF_SCSI_ID;  

        ((struct cciss_scsi_adapter_data_t *) 
                hba[ctlr]->scsi_ctlr)->scsi_host = (void *) sh;
        sh->hostdata[0] = (unsigned long) hba[ctlr];
        sh->irq = hba[ctlr]->intr;
        sh->unique_id = sh->irq;
        error = scsi_add_host(sh, &hba[ctlr]->pdev->dev);
        if (error)
                goto fail_host_put;
        scsi_scan_host(sh);
        return 1;

 fail_host_put:
        scsi_host_put(sh);
 fail:
        return 0;
}

static void
cciss_unmap_one(struct pci_dev *pdev,
                CommandList_struct *cp,
                size_t buflen,
                int data_direction)
{
        u64bit addr64;

        addr64.val32.lower = cp->SG[0].Addr.lower;
        addr64.val32.upper = cp->SG[0].Addr.upper;
        pci_unmap_single(pdev, (dma_addr_t) addr64.val, buflen, data_direction);
}

static void
cciss_map_one(struct pci_dev *pdev,
                CommandList_struct *cp,
                unsigned char *buf,
                size_t buflen,
                int data_direction)
{
        __u64 addr64;

        addr64 = (__u64) pci_map_single(pdev, buf, buflen, data_direction);
        cp->SG[0].Addr.lower = 
          (__u32) (addr64 & (__u64) 0x00000000FFFFFFFF);
        cp->SG[0].Addr.upper =
          (__u32) ((addr64 >> 32) & (__u64) 0x00000000FFFFFFFF);
        cp->SG[0].Len = buflen;
        cp->Header.SGList = (__u8) 1;   /* no. SGs contig in this cmd */
        cp->Header.SGTotal = (__u16) 1; /* total sgs in this cmd list */
}

static int
cciss_scsi_do_simple_cmd(ctlr_info_t *c,
                        CommandList_struct *cp,
                        unsigned char *scsi3addr, 
                        unsigned char *cdb,
                        unsigned char cdblen,
                        unsigned char *buf, int bufsize,
                        int direction)
{
        unsigned long flags;
        DECLARE_COMPLETION(wait);

        cp->cmd_type = CMD_IOCTL_PEND;          // treat this like an ioctl 
        cp->scsi_cmd = NULL;
        cp->Header.ReplyQueue = 0;  // unused in simple mode
        memcpy(&cp->Header.LUN, scsi3addr, sizeof(cp->Header.LUN));
        cp->Header.Tag.lower = cp->busaddr;  // Use k. address of cmd as tag
        // Fill in the request block...

        /* printk("Using scsi3addr 0x%02x%0x2%0x2%0x2%0x2%0x2%0x2%0x2\n", 
                scsi3addr[0], scsi3addr[1], scsi3addr[2], scsi3addr[3],
                scsi3addr[4], scsi3addr[5], scsi3addr[6], scsi3addr[7]); */

        memset(cp->Request.CDB, 0, sizeof(cp->Request.CDB));
        memcpy(cp->Request.CDB, cdb, cdblen);
        cp->Request.Timeout = 0;
        cp->Request.CDBLen = cdblen;
        cp->Request.Type.Type = TYPE_CMD;
        cp->Request.Type.Attribute = ATTR_SIMPLE;
        cp->Request.Type.Direction = direction;

        /* Fill in the SG list and do dma mapping */
        cciss_map_one(c->pdev, cp, (unsigned char *) buf,
                        bufsize, DMA_FROM_DEVICE); 

        cp->waiting = &wait;

        /* Put the request on the tail of the request queue */
        spin_lock_irqsave(CCISS_LOCK(c->ctlr), flags);
        addQ(&c->reqQ, cp);
        c->Qdepth++;
        start_io(c);
        spin_unlock_irqrestore(CCISS_LOCK(c->ctlr), flags);

        wait_for_completion(&wait);

        /* undo the dma mapping */
        cciss_unmap_one(c->pdev, cp, bufsize, DMA_FROM_DEVICE);
        return(0);
}

static void 
cciss_scsi_interpret_error(CommandList_struct *cp)
{
        ErrorInfo_struct *ei;

        ei = cp->err_info; 
        switch(ei->CommandStatus)
        {
                case CMD_TARGET_STATUS:
                        printk(KERN_WARNING "cciss: cmd %p has "
                                "completed with errors\n", cp);
                        printk(KERN_WARNING "cciss: cmd %p "
                                "has SCSI Status = %x\n",
                                        cp,  
                                        ei->ScsiStatus);
                        if (ei->ScsiStatus == 0)
                                printk(KERN_WARNING 
                                "cciss:SCSI status is abnormally zero.  "
                                "(probably indicates selection timeout "
                                "reported incorrectly due to a known "
                                "firmware bug, circa July, 2001.)\n");
                break;
                case CMD_DATA_UNDERRUN: /* let mid layer handle it. */
                        printk("UNDERRUN\n");
                break;
                case CMD_DATA_OVERRUN:
                        printk(KERN_WARNING "cciss: cp %p has"
                                " completed with data overrun "
                                "reported\n", cp);
                break;
                case CMD_INVALID: {
                        /* controller unfortunately reports SCSI passthru's */
                        /* to non-existent targets as invalid commands. */
                        printk(KERN_WARNING "cciss: cp %p is "
                                "reported invalid (probably means "
                                "target device no longer present)\n", 
                                cp); 
                        /* print_bytes((unsigned char *) cp, sizeof(*cp), 1, 0);
                        print_cmd(cp);  */
                        }
                break;
                case CMD_PROTOCOL_ERR:
                        printk(KERN_WARNING "cciss: cp %p has "
                                "protocol error \n", cp);
                break;
                case CMD_HARDWARE_ERR:
                        /* cmd->result = DID_ERROR << 16; */
                        printk(KERN_WARNING "cciss: cp %p had " 
                                " hardware error\n", cp);
                break;
                case CMD_CONNECTION_LOST:
                        printk(KERN_WARNING "cciss: cp %p had "
                                "connection lost\n", cp);
                break;
                case CMD_ABORTED:
                        printk(KERN_WARNING "cciss: cp %p was "
                                "aborted\n", cp);
                break;
                case CMD_ABORT_FAILED:
                        printk(KERN_WARNING "cciss: cp %p reports "
                                "abort failed\n", cp);
                break;
                case CMD_UNSOLICITED_ABORT:
                        printk(KERN_WARNING "cciss: cp %p aborted "
                                "do to an unsolicited abort\n", cp);
                break;
                case CMD_TIMEOUT:
                        printk(KERN_WARNING "cciss: cp %p timedout\n",
                                cp);
                break;
                default:
                        printk(KERN_WARNING "cciss: cp %p returned "
                                "unknown status %x\n", cp, 
                                        ei->CommandStatus); 
        }
}

static int
cciss_scsi_do_inquiry(ctlr_info_t *c, unsigned char *scsi3addr, 
                 InquiryData_struct *buf)
{
        int rc;
        CommandList_struct *cp;
        char cdb[6];
        ErrorInfo_struct *ei;
        unsigned long flags;

        spin_lock_irqsave(CCISS_LOCK(c->ctlr), flags);
        cp = scsi_cmd_alloc(c);
        spin_unlock_irqrestore(CCISS_LOCK(c->ctlr), flags);

        if (cp == NULL) {                       /* trouble... */
                printk("cmd_alloc returned NULL!\n");
                return -1;
        }

        ei = cp->err_info; 

        cdb[0] = CISS_INQUIRY;
        cdb[1] = 0;
        cdb[2] = 0;
        cdb[3] = 0;
        cdb[4] = sizeof(*buf) & 0xff;
        cdb[5] = 0;
        rc = cciss_scsi_do_simple_cmd(c, cp, scsi3addr, cdb, 
                                6, (unsigned char *) buf, 
                                sizeof(*buf), XFER_READ);

        if (rc != 0) return rc; /* something went wrong */

        if (ei->CommandStatus != 0 && 
            ei->CommandStatus != CMD_DATA_UNDERRUN) {
                cciss_scsi_interpret_error(cp);
                rc = -1;
        }
        spin_lock_irqsave(CCISS_LOCK(c->ctlr), flags);
        scsi_cmd_free(c, cp);
        spin_unlock_irqrestore(CCISS_LOCK(c->ctlr), flags);
        return rc;      
}

static int
cciss_scsi_do_report_phys_luns(ctlr_info_t *c, 
                ReportLunData_struct *buf, int bufsize)
{
        int rc;
        CommandList_struct *cp;
        unsigned char cdb[12];
        unsigned char scsi3addr[8]; 
        ErrorInfo_struct *ei;
        unsigned long flags;

        spin_lock_irqsave(CCISS_LOCK(c->ctlr), flags);
        cp = scsi_cmd_alloc(c);
        spin_unlock_irqrestore(CCISS_LOCK(c->ctlr), flags);
        if (cp == NULL) {                       /* trouble... */
                printk("cmd_alloc returned NULL!\n");
                return -1;
        }

        memset(&scsi3addr[0], 0, 8); /* address the controller */
        cdb[0] = CISS_REPORT_PHYS;
        cdb[1] = 0;
        cdb[2] = 0;
        cdb[3] = 0;
        cdb[4] = 0;
        cdb[5] = 0;
        cdb[6] = (bufsize >> 24) & 0xFF;  //MSB
        cdb[7] = (bufsize >> 16) & 0xFF;
        cdb[8] = (bufsize >> 8) & 0xFF;
        cdb[9] = bufsize & 0xFF;
        cdb[10] = 0;
        cdb[11] = 0;

        rc = cciss_scsi_do_simple_cmd(c, cp, scsi3addr, 
                                cdb, 12, 
                                (unsigned char *) buf, 
                                bufsize, XFER_READ);

        if (rc != 0) return rc; /* something went wrong */

        ei = cp->err_info; 
        if (ei->CommandStatus != 0 && 
            ei->CommandStatus != CMD_DATA_UNDERRUN) {
                cciss_scsi_interpret_error(cp);
                rc = -1;
        }
        spin_lock_irqsave(CCISS_LOCK(c->ctlr), flags);
        scsi_cmd_free(c, cp);
        spin_unlock_irqrestore(CCISS_LOCK(c->ctlr), flags);
        return rc;      
}

static void
cciss_update_non_disk_devices(int cntl_num, int hostno)
{
        /* the idea here is we could get notified from /proc
           that some devices have changed, so we do a report 
           physical luns cmd, and adjust our list of devices 
           accordingly.  (We can't rely on the scsi-mid layer just
           doing inquiries, because the "busses" that the scsi 
           mid-layer probes are totally fabricated by this driver,
           so new devices wouldn't show up.

           the scsi3addr's of devices won't change so long as the 
           adapter is not reset.  That means we can rescan and 
           tell which devices we already know about, vs. new 
           devices, vs.  disappearing devices.

           Also, if you yank out a tape drive, then put in a disk
           in it's place, (say, a configured volume from another 
           array controller for instance)  _don't_ poke this driver 
           (so it thinks it's still a tape, but _do_ poke the scsi 
           mid layer, so it does an inquiry... the scsi mid layer 
           will see the physical disk.  This would be bad.  Need to
           think about how to prevent that.  One idea would be to 
           snoop all scsi responses and if an inquiry repsonse comes
           back that reports a disk, chuck it an return selection
           timeout instead and adjust our table...  Not sure i like
           that though.  

         */

        ReportLunData_struct *ld_buff;
        InquiryData_struct *inq_buff;
        unsigned char scsi3addr[8];
        ctlr_info_t *c;
        __u32 num_luns=0;
        unsigned char *ch;
        /* unsigned char found[CCISS_MAX_SCSI_DEVS_PER_HBA]; */
        struct cciss_scsi_dev_t currentsd[CCISS_MAX_SCSI_DEVS_PER_HBA];
        int ncurrent=0;
        int reportlunsize = sizeof(*ld_buff) + CISS_MAX_PHYS_LUN * 8;
        int i;

        c = (ctlr_info_t *) hba[cntl_num];      
        ld_buff = kmalloc(reportlunsize, GFP_KERNEL);
        if (ld_buff == NULL) {
                printk(KERN_ERR "cciss: out of memory\n");
                return;
        }
        memset(ld_buff, 0, reportlunsize);
        inq_buff = kmalloc(sizeof( InquiryData_struct), GFP_KERNEL);
        if (inq_buff == NULL) {
                printk(KERN_ERR "cciss: out of memory\n");
                kfree(ld_buff);
                return;
        }

        if (cciss_scsi_do_report_phys_luns(c, ld_buff, reportlunsize) == 0) {
                ch = &ld_buff->LUNListLength[0];
                num_luns = ((ch[0]<<24) | (ch[1]<<16) | (ch[2]<<8) | ch[3]) / 8;
                if (num_luns > CISS_MAX_PHYS_LUN) {
                        printk(KERN_WARNING 
                                "cciss: Maximum physical LUNs (%d) exceeded.  "
                                "%d LUNs ignored.\n", CISS_MAX_PHYS_LUN, 
                                num_luns - CISS_MAX_PHYS_LUN);
                        num_luns = CISS_MAX_PHYS_LUN;
                }
        }
        else {
                printk(KERN_ERR  "cciss: Report physical LUNs failed.\n");
                goto out;
        }


        /* adjust our table of devices */       
        for(i=0; i<num_luns; i++)
        {
                int devtype;

                /* for each physical lun, do an inquiry */
                if (ld_buff->LUN[i][3] & 0xC0) continue;
                memset(inq_buff, 0, sizeof(InquiryData_struct));
                memcpy(&scsi3addr[0], &ld_buff->LUN[i][0], 8);

                if (cciss_scsi_do_inquiry(hba[cntl_num], 
                        scsi3addr, inq_buff) != 0)
                {
                        /* Inquiry failed (msg printed already) */
                        devtype = 0; /* so we will skip this device. */
                } else /* what kind of device is this? */
                        devtype = (inq_buff->data_byte[0] & 0x1f);

                switch (devtype)
                {
                  case 0x01: /* sequential access, (tape) */
                  case 0x08: /* medium changer */
                        if (ncurrent >= CCISS_MAX_SCSI_DEVS_PER_HBA) {
                                printk(KERN_INFO "cciss%d: %s ignored, "
                                        "too many devices.\n", cntl_num,
                                        DEVICETYPE(devtype));
                                break;
                        }
                        memcpy(&currentsd[ncurrent].scsi3addr[0], 
                                &scsi3addr[0], 8);
                        currentsd[ncurrent].devtype = devtype;
                        currentsd[ncurrent].bus = -1;
                        currentsd[ncurrent].target = -1;
                        currentsd[ncurrent].lun = -1;
                        ncurrent++;
                        break;
                  default: 
                        break;
                }
        }

        adjust_cciss_scsi_table(cntl_num, hostno, currentsd, ncurrent);
out:
        kfree(inq_buff);
        kfree(ld_buff);
        return;
}

static int
is_keyword(char *ptr, int len, char *verb)  // Thanks to ncr53c8xx.c
{
        int verb_len = strlen(verb);
        if (len >= verb_len && !memcmp(verb,ptr,verb_len))
                return verb_len;
        else
                return 0;
}

static int
cciss_scsi_user_command(int ctlr, int hostno, char *buffer, int length)
{
        int arg_len;

        if ((arg_len = is_keyword(buffer, length, "rescan")) != 0)
                cciss_update_non_disk_devices(ctlr, hostno);
        else
                return -EINVAL;
        return length;
}


static int
cciss_scsi_proc_info(struct Scsi_Host *sh,
                char *buffer, /* data buffer */
                char **start,      /* where data in buffer starts */
                off_t offset,      /* offset from start of imaginary file */
                int length,        /* length of data in buffer */
                int func)          /* 0 == read, 1 == write */
{

        int buflen, datalen;
        ctlr_info_t *ci;
        int cntl_num;


        ci = (ctlr_info_t *) sh->hostdata[0];
        if (ci == NULL)  /* This really shouldn't ever happen. */
                return -EINVAL;

        cntl_num = ci->ctlr;    /* Get our index into the hba[] array */

        if (func == 0) {        /* User is reading from /proc/scsi/ciss*?/?*  */
                buflen = sprintf(buffer, "hostnum=%d\n", sh->host_no);  

                datalen = buflen - offset;
                if (datalen < 0) {      /* they're reading past EOF. */
                        datalen = 0;
                        *start = buffer+buflen; 
                } else
                        *start = buffer + offset;
                return(datalen);
        } else  /* User is writing to /proc/scsi/cciss*?/?*  ... */
                return cciss_scsi_user_command(cntl_num, sh->host_no,
                        buffer, length);        
} 

/* cciss_scatter_gather takes a struct scsi_cmnd, (cmd), and does the pci 
   dma mapping  and fills in the scatter gather entries of the 
   cciss command, cp. */

static void
cciss_scatter_gather(struct pci_dev *pdev, 
                CommandList_struct *cp, 
                struct scsi_cmnd *cmd)
{
        unsigned int use_sg, nsegs=0, len;
        struct scatterlist *scatter = (struct scatterlist *) cmd->buffer;
        __u64 addr64;

        /* is it just one virtual address? */   
        if (!cmd->use_sg) {
                if (cmd->request_bufflen) {     /* anything to xfer? */

                        addr64 = (__u64) pci_map_single(pdev, 
                                cmd->request_buffer, 
                                cmd->request_bufflen, 
                                cmd->sc_data_direction); 
        
                        cp->SG[0].Addr.lower = 
                          (__u32) (addr64 & (__u64) 0x00000000FFFFFFFF);
                        cp->SG[0].Addr.upper =
                          (__u32) ((addr64 >> 32) & (__u64) 0x00000000FFFFFFFF);
                        cp->SG[0].Len = cmd->request_bufflen;
                        nsegs=1;
                }
        } /* else, must be a list of virtual addresses.... */
        else if (cmd->use_sg <= MAXSGENTRIES) { /* not too many addrs? */

                use_sg = pci_map_sg(pdev, cmd->buffer, cmd->use_sg, 
                        cmd->sc_data_direction);

                for (nsegs=0; nsegs < use_sg; nsegs++) {
                        addr64 = (__u64) sg_dma_address(&scatter[nsegs]);
                        len  = sg_dma_len(&scatter[nsegs]);
                        cp->SG[nsegs].Addr.lower =
                          (__u32) (addr64 & (__u64) 0x00000000FFFFFFFF);
                        cp->SG[nsegs].Addr.upper =
                          (__u32) ((addr64 >> 32) & (__u64) 0x00000000FFFFFFFF);
                        cp->SG[nsegs].Len = len;
                        cp->SG[nsegs].Ext = 0;  // we are not chaining
                }
        } else BUG();

        cp->Header.SGList = (__u8) nsegs;   /* no. SGs contig in this cmd */
        cp->Header.SGTotal = (__u16) nsegs; /* total sgs in this cmd list */
        return;
}


static int
cciss_scsi_queue_command (struct scsi_cmnd *cmd, void (* done)(struct scsi_cmnd *))
{
        ctlr_info_t **c;
        int ctlr, rc;
        unsigned char scsi3addr[8];
        CommandList_struct *cp;
        unsigned long flags;

        // Get the ptr to our adapter structure (hba[i]) out of cmd->host.
        // We violate cmd->host privacy here.  (Is there another way?)
        c = (ctlr_info_t **) &cmd->device->host->hostdata[0];   
        ctlr = (*c)->ctlr;

        rc = lookup_scsi3addr(ctlr, cmd->device->channel, cmd->device->id, 
                        cmd->device->lun, scsi3addr);
        if (rc != 0) {
                /* the scsi nexus does not match any that we presented... */
                /* pretend to mid layer that we got selection timeout */
                cmd->result = DID_NO_CONNECT << 16;
                done(cmd);
                /* we might want to think about registering controller itself
                   as a processor device on the bus so sg binds to it. */
                return 0;
        }

        /* printk("cciss_queue_command, p=%p, cmd=0x%02x, c%db%dt%dl%d\n", 
                cmd, cmd->cmnd[0], ctlr, cmd->channel, cmd->target, cmd->lun);*/
        // printk("q:%p:c%db%dt%dl%d ", cmd, ctlr, cmd->channel, 
        //      cmd->target, cmd->lun);

        /* Ok, we have a reasonable scsi nexus, so send the cmd down, and
           see what the device thinks of it. */

        spin_lock_irqsave(CCISS_LOCK(ctlr), flags);
        cp = scsi_cmd_alloc(*c);
        spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);
        if (cp == NULL) {                       /* trouble... */
                printk("scsi_cmd_alloc returned NULL!\n");
                /* FIXME: next 3 lines are -> BAD! <- */
                cmd->result = DID_NO_CONNECT << 16;
                done(cmd);
                return 0;
        }

        // Fill in the command list header

        cmd->scsi_done = done;    // save this for use by completion code 

        // save cp in case we have to abort it 
        cmd->host_scribble = (unsigned char *) cp; 

        cp->cmd_type = CMD_SCSI;
        cp->scsi_cmd = cmd;
        cp->Header.ReplyQueue = 0;  // unused in simple mode
        memcpy(&cp->Header.LUN.LunAddrBytes[0], &scsi3addr[0], 8);
        cp->Header.Tag.lower = cp->busaddr;  // Use k. address of cmd as tag
        
        // Fill in the request block...

        cp->Request.Timeout = 0;
        memset(cp->Request.CDB, 0, sizeof(cp->Request.CDB));
        if (cmd->cmd_len > sizeof(cp->Request.CDB)) BUG();
        cp->Request.CDBLen = cmd->cmd_len;
        memcpy(cp->Request.CDB, cmd->cmnd, cmd->cmd_len);
        cp->Request.Type.Type = TYPE_CMD;
        cp->Request.Type.Attribute = ATTR_SIMPLE;
        switch(cmd->sc_data_direction)
        {
          case DMA_TO_DEVICE: cp->Request.Type.Direction = XFER_WRITE; break;
          case DMA_FROM_DEVICE: cp->Request.Type.Direction = XFER_READ; break;
          case DMA_NONE: cp->Request.Type.Direction = XFER_NONE; break;
          case DMA_BIDIRECTIONAL:
                // This can happen if a buggy application does a scsi passthru
                // and sets both inlen and outlen to non-zero. ( see
                // ../scsi/scsi_ioctl.c:scsi_ioctl_send_command() )

                cp->Request.Type.Direction = XFER_RSVD;
                // This is technically wrong, and cciss controllers should
                // reject it with CMD_INVALID, which is the most correct 
                // response, but non-fibre backends appear to let it 
                // slide by, and give the same results as if this field
                // were set correctly.  Either way is acceptable for
                // our purposes here.

                break;

          default: 
                printk("cciss: unknown data direction: %d\n", 
                        cmd->sc_data_direction);
                BUG();
                break;
        }

        cciss_scatter_gather((*c)->pdev, cp, cmd); // Fill the SG list

        /* Put the request on the tail of the request queue */

        spin_lock_irqsave(CCISS_LOCK(ctlr), flags);
        addQ(&(*c)->reqQ, cp);
        (*c)->Qdepth++;
        start_io(*c);
        spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);

        /* the cmd'll come back via intr handler in complete_scsi_command()  */
        return 0;
}

static void 
cciss_unregister_scsi(int ctlr)
{
        struct cciss_scsi_adapter_data_t *sa;
        struct cciss_scsi_cmd_stack_t *stk;
        unsigned long flags;

        /* we are being forcibly unloaded, and may not refuse. */

        spin_lock_irqsave(CCISS_LOCK(ctlr), flags);
        sa = (struct cciss_scsi_adapter_data_t *) hba[ctlr]->scsi_ctlr;
        stk = &sa->cmd_stack; 

        /* if we weren't ever actually registered, don't unregister */ 
        if (sa->registered) {
                spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);
                scsi_remove_host(sa->scsi_host);
                scsi_host_put(sa->scsi_host);
                spin_lock_irqsave(CCISS_LOCK(ctlr), flags);
        }

        /* set scsi_host to NULL so our detect routine will 
           find us on register */
        sa->scsi_host = NULL;
        scsi_cmd_stack_free(ctlr);
        kfree(sa);
        spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);
}

static int 
cciss_register_scsi(int ctlr)
{
        unsigned long flags;

        CPQ_TAPE_LOCK(ctlr, flags);

        /* Since this is really a block driver, the SCSI core may not be 
           initialized at init time, in which case, calling scsi_register_host
           would hang.  Instead, we do it later, via /proc filesystem
           and rc scripts, when we know SCSI core is good to go. */

        /* Only register if SCSI devices are detected. */
        if (ccissscsi[ctlr].ndevices != 0) {
                ((struct cciss_scsi_adapter_data_t *) 
                        hba[ctlr]->scsi_ctlr)->registered = 1;
                CPQ_TAPE_UNLOCK(ctlr, flags);
                return cciss_scsi_detect(ctlr);
        }
        CPQ_TAPE_UNLOCK(ctlr, flags);
        printk(KERN_INFO 
                "cciss%d: No appropriate SCSI device detected, "
                "SCSI subsystem not engaged.\n", ctlr);
        return 0;
}

static int 
cciss_engage_scsi(int ctlr)
{
        struct cciss_scsi_adapter_data_t *sa;
        struct cciss_scsi_cmd_stack_t *stk;
        unsigned long flags;

        spin_lock_irqsave(CCISS_LOCK(ctlr), flags);
        sa = (struct cciss_scsi_adapter_data_t *) hba[ctlr]->scsi_ctlr;
        stk = &sa->cmd_stack; 

        if (((struct cciss_scsi_adapter_data_t *) 
                hba[ctlr]->scsi_ctlr)->registered) {
                printk("cciss%d: SCSI subsystem already engaged.\n", ctlr);
                spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);
                return ENXIO;
        }
        spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);
        cciss_update_non_disk_devices(ctlr, -1);
        cciss_register_scsi(ctlr);
        return 0;
}

static void
cciss_proc_tape_report(int ctlr, unsigned char *buffer, off_t *pos, off_t *len)
{
        unsigned long flags;
        int size;

        *pos = *pos -1; *len = *len - 1; // cut off the last trailing newline

        CPQ_TAPE_LOCK(ctlr, flags);
        size = sprintf(buffer + *len, 
                "       Sequential access devices: %d\n\n",
                        ccissscsi[ctlr].ndevices);
        CPQ_TAPE_UNLOCK(ctlr, flags);
        *pos += size; *len += size;
}

#else /* no CONFIG_CISS_SCSI_TAPE */

/* If no tape support, then these become defined out of existence */

#define cciss_scsi_setup(cntl_num)
#define cciss_unregister_scsi(ctlr)
#define cciss_register_scsi(ctlr)
#define cciss_proc_tape_report(ctlr, buffer, pos, len)

#endif /* CONFIG_CISS_SCSI_TAPE */