Pull acpi_os_free into release branch

[linux-2.6] / drivers / scsi / libata-scsi.c

/*
 *  libata-scsi.c - helper library for ATA
 *
 *  Maintained by:  Jeff Garzik <jgarzik@pobox.com>
 *                  Please ALWAYS copy linux-ide@vger.kernel.org
 *                  on emails.
 *
 *  Copyright 2003-2004 Red Hat, Inc.  All rights reserved.
 *  Copyright 2003-2004 Jeff Garzik
 *
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 *  libata documentation is available via 'make {ps|pdf}docs',
 *  as Documentation/DocBook/libata.*
 *
 *  Hardware documentation available from
 *  - http://www.t10.org/
 *  - http://www.t13.org/
 *
 */

#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/spinlock.h>
#include <scsi/scsi.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_transport.h>
#include <linux/libata.h>
#include <linux/hdreg.h>
#include <asm/uaccess.h>

#include "libata.h"

#define SECTOR_SIZE     512

typedef unsigned int (*ata_xlat_func_t)(struct ata_queued_cmd *qc, const u8 *scsicmd);

static struct ata_device * __ata_scsi_find_dev(struct ata_port *ap,
                                        const struct scsi_device *scsidev);
static struct ata_device * ata_scsi_find_dev(struct ata_port *ap,
                                            const struct scsi_device *scsidev);
static int ata_scsi_user_scan(struct Scsi_Host *shost, unsigned int channel,
                              unsigned int id, unsigned int lun);


#define RW_RECOVERY_MPAGE 0x1
#define RW_RECOVERY_MPAGE_LEN 12
#define CACHE_MPAGE 0x8
#define CACHE_MPAGE_LEN 20
#define CONTROL_MPAGE 0xa
#define CONTROL_MPAGE_LEN 12
#define ALL_MPAGES 0x3f
#define ALL_SUB_MPAGES 0xff


static const u8 def_rw_recovery_mpage[] = {
        RW_RECOVERY_MPAGE,
        RW_RECOVERY_MPAGE_LEN - 2,
        (1 << 7) |      /* AWRE, sat-r06 say it shall be 0 */
            (1 << 6),   /* ARRE (auto read reallocation) */
        0,              /* read retry count */
        0, 0, 0, 0,
        0,              /* write retry count */
        0, 0, 0
};

static const u8 def_cache_mpage[CACHE_MPAGE_LEN] = {
        CACHE_MPAGE,
        CACHE_MPAGE_LEN - 2,
        0,              /* contains WCE, needs to be 0 for logic */
        0, 0, 0, 0, 0, 0, 0, 0, 0,
        0,              /* contains DRA, needs to be 0 for logic */
        0, 0, 0, 0, 0, 0, 0
};

static const u8 def_control_mpage[CONTROL_MPAGE_LEN] = {
        CONTROL_MPAGE,
        CONTROL_MPAGE_LEN - 2,
        2,      /* DSENSE=0, GLTSD=1 */
        0,      /* [QAM+QERR may be 1, see 05-359r1] */
        0, 0, 0, 0, 0xff, 0xff,
        0, 30   /* extended self test time, see 05-359r1 */
};

/*
 * libata transport template.  libata doesn't do real transport stuff.
 * It just needs the eh_timed_out hook.
 */
struct scsi_transport_template ata_scsi_transport_template = {
        .eh_strategy_handler    = ata_scsi_error,
        .eh_timed_out           = ata_scsi_timed_out,
        .user_scan              = ata_scsi_user_scan,
};


static void ata_scsi_invalid_field(struct scsi_cmnd *cmd,
                                   void (*done)(struct scsi_cmnd *))
{
        ata_scsi_set_sense(cmd, ILLEGAL_REQUEST, 0x24, 0x0);
        /* "Invalid field in cbd" */
        done(cmd);
}

/**
 *      ata_std_bios_param - generic bios head/sector/cylinder calculator used by sd.
 *      @sdev: SCSI device for which BIOS geometry is to be determined
 *      @bdev: block device associated with @sdev
 *      @capacity: capacity of SCSI device
 *      @geom: location to which geometry will be output
 *
 *      Generic bios head/sector/cylinder calculator
 *      used by sd. Most BIOSes nowadays expect a XXX/255/16  (CHS)
 *      mapping. Some situations may arise where the disk is not
 *      bootable if this is not used.
 *
 *      LOCKING:
 *      Defined by the SCSI layer.  We don't really care.
 *
 *      RETURNS:
 *      Zero.
 */
int ata_std_bios_param(struct scsi_device *sdev, struct block_device *bdev,
                       sector_t capacity, int geom[])
{
        geom[0] = 255;
        geom[1] = 63;
        sector_div(capacity, 255*63);
        geom[2] = capacity;

        return 0;
}

/**
 *      ata_cmd_ioctl - Handler for HDIO_DRIVE_CMD ioctl
 *      @scsidev: Device to which we are issuing command
 *      @arg: User provided data for issuing command
 *
 *      LOCKING:
 *      Defined by the SCSI layer.  We don't really care.
 *
 *      RETURNS:
 *      Zero on success, negative errno on error.
 */

int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg)
{
        int rc = 0;
        u8 scsi_cmd[MAX_COMMAND_SIZE];
        u8 args[4], *argbuf = NULL;
        int argsize = 0;
        struct scsi_sense_hdr sshdr;
        enum dma_data_direction data_dir;

        if (arg == NULL)
                return -EINVAL;

        if (copy_from_user(args, arg, sizeof(args)))
                return -EFAULT;

        memset(scsi_cmd, 0, sizeof(scsi_cmd));

        if (args[3]) {
                argsize = SECTOR_SIZE * args[3];
                argbuf = kmalloc(argsize, GFP_KERNEL);
                if (argbuf == NULL) {
                        rc = -ENOMEM;
                        goto error;
                }

                scsi_cmd[1]  = (4 << 1); /* PIO Data-in */
                scsi_cmd[2]  = 0x0e;     /* no off.line or cc, read from dev,
                                            block count in sector count field */
                data_dir = DMA_FROM_DEVICE;
        } else {
                scsi_cmd[1]  = (3 << 1); /* Non-data */
                /* scsi_cmd[2] is already 0 -- no off.line, cc, or data xfer */
                data_dir = DMA_NONE;
        }

        scsi_cmd[0] = ATA_16;

        scsi_cmd[4] = args[2];
        if (args[0] == WIN_SMART) { /* hack -- ide driver does this too... */
                scsi_cmd[6]  = args[3];
                scsi_cmd[8]  = args[1];
                scsi_cmd[10] = 0x4f;
                scsi_cmd[12] = 0xc2;
        } else {
                scsi_cmd[6]  = args[1];
        }
        scsi_cmd[14] = args[0];

        /* Good values for timeout and retries?  Values below
           from scsi_ioctl_send_command() for default case... */
        if (scsi_execute_req(scsidev, scsi_cmd, data_dir, argbuf, argsize,
                             &sshdr, (10*HZ), 5)) {
                rc = -EIO;
                goto error;
        }

        /* Need code to retrieve data from check condition? */

        if ((argbuf)
         && copy_to_user(arg + sizeof(args), argbuf, argsize))
                rc = -EFAULT;
error:
        kfree(argbuf);
        return rc;
}

/**
 *      ata_task_ioctl - Handler for HDIO_DRIVE_TASK ioctl
 *      @scsidev: Device to which we are issuing command
 *      @arg: User provided data for issuing command
 *
 *      LOCKING:
 *      Defined by the SCSI layer.  We don't really care.
 *
 *      RETURNS:
 *      Zero on success, negative errno on error.
 */
int ata_task_ioctl(struct scsi_device *scsidev, void __user *arg)
{
        int rc = 0;
        u8 scsi_cmd[MAX_COMMAND_SIZE];
        u8 args[7];
        struct scsi_sense_hdr sshdr;

        if (arg == NULL)
                return -EINVAL;

        if (copy_from_user(args, arg, sizeof(args)))
                return -EFAULT;

        memset(scsi_cmd, 0, sizeof(scsi_cmd));
        scsi_cmd[0]  = ATA_16;
        scsi_cmd[1]  = (3 << 1); /* Non-data */
        /* scsi_cmd[2] is already 0 -- no off.line, cc, or data xfer */
        scsi_cmd[4]  = args[1];
        scsi_cmd[6]  = args[2];
        scsi_cmd[8]  = args[3];
        scsi_cmd[10] = args[4];
        scsi_cmd[12] = args[5];
        scsi_cmd[14] = args[0];

        /* Good values for timeout and retries?  Values below
           from scsi_ioctl_send_command() for default case... */
        if (scsi_execute_req(scsidev, scsi_cmd, DMA_NONE, NULL, 0, &sshdr,
                             (10*HZ), 5))
                rc = -EIO;

        /* Need code to retrieve data from check condition? */
        return rc;
}

int ata_scsi_ioctl(struct scsi_device *scsidev, int cmd, void __user *arg)
{
        int val = -EINVAL, rc = -EINVAL;

        switch (cmd) {
        case ATA_IOC_GET_IO32:
                val = 0;
                if (copy_to_user(arg, &val, 1))
                        return -EFAULT;
                return 0;

        case ATA_IOC_SET_IO32:
                val = (unsigned long) arg;
                if (val != 0)
                        return -EINVAL;
                return 0;

        case HDIO_DRIVE_CMD:
                if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
                        return -EACCES;
                return ata_cmd_ioctl(scsidev, arg);

        case HDIO_DRIVE_TASK:
                if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
                        return -EACCES;
                return ata_task_ioctl(scsidev, arg);

        default:
                rc = -ENOTTY;
                break;
        }

        return rc;
}

/**
 *      ata_scsi_qc_new - acquire new ata_queued_cmd reference
 *      @dev: ATA device to which the new command is attached
 *      @cmd: SCSI command that originated this ATA command
 *      @done: SCSI command completion function
 *
 *      Obtain a reference to an unused ata_queued_cmd structure,
 *      which is the basic libata structure representing a single
 *      ATA command sent to the hardware.
 *
 *      If a command was available, fill in the SCSI-specific
 *      portions of the structure with information on the
 *      current command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Command allocated, or %NULL if none available.
 */
struct ata_queued_cmd *ata_scsi_qc_new(struct ata_device *dev,
                                       struct scsi_cmnd *cmd,
                                       void (*done)(struct scsi_cmnd *))
{
        struct ata_queued_cmd *qc;

        qc = ata_qc_new_init(dev);
        if (qc) {
                qc->scsicmd = cmd;
                qc->scsidone = done;

                if (cmd->use_sg) {
                        qc->__sg = (struct scatterlist *) cmd->request_buffer;
                        qc->n_elem = cmd->use_sg;
                } else {
                        qc->__sg = &qc->sgent;
                        qc->n_elem = 1;
                }
        } else {
                cmd->result = (DID_OK << 16) | (QUEUE_FULL << 1);
                done(cmd);
        }

        return qc;
}

/**
 *      ata_dump_status - user friendly display of error info
 *      @id: id of the port in question
 *      @tf: ptr to filled out taskfile
 *
 *      Decode and dump the ATA error/status registers for the user so
 *      that they have some idea what really happened at the non
 *      make-believe layer.
 *
 *      LOCKING:
 *      inherited from caller
 */
void ata_dump_status(unsigned id, struct ata_taskfile *tf)
{
        u8 stat = tf->command, err = tf->feature;

        printk(KERN_WARNING "ata%u: status=0x%02x { ", id, stat);
        if (stat & ATA_BUSY) {
                printk("Busy }\n");     /* Data is not valid in this case */
        } else {
                if (stat & 0x40)        printk("DriveReady ");
                if (stat & 0x20)        printk("DeviceFault ");
                if (stat & 0x10)        printk("SeekComplete ");
                if (stat & 0x08)        printk("DataRequest ");
                if (stat & 0x04)        printk("CorrectedError ");
                if (stat & 0x02)        printk("Index ");
                if (stat & 0x01)        printk("Error ");
                printk("}\n");

                if (err) {
                        printk(KERN_WARNING "ata%u: error=0x%02x { ", id, err);
                        if (err & 0x04)         printk("DriveStatusError ");
                        if (err & 0x80) {
                                if (err & 0x04) printk("BadCRC ");
                                else            printk("Sector ");
                        }
                        if (err & 0x40)         printk("UncorrectableError ");
                        if (err & 0x10)         printk("SectorIdNotFound ");
                        if (err & 0x02)         printk("TrackZeroNotFound ");
                        if (err & 0x01)         printk("AddrMarkNotFound ");
                        printk("}\n");
                }
        }
}

int ata_scsi_device_resume(struct scsi_device *sdev)
{
        struct ata_port *ap = ata_shost_to_port(sdev->host);
        struct ata_device *dev = __ata_scsi_find_dev(ap, sdev);

        return ata_device_resume(dev);
}

int ata_scsi_device_suspend(struct scsi_device *sdev, pm_message_t state)
{
        struct ata_port *ap = ata_shost_to_port(sdev->host);
        struct ata_device *dev = __ata_scsi_find_dev(ap, sdev);

        return ata_device_suspend(dev, state);
}

/**
 *      ata_to_sense_error - convert ATA error to SCSI error
 *      @id: ATA device number
 *      @drv_stat: value contained in ATA status register
 *      @drv_err: value contained in ATA error register
 *      @sk: the sense key we'll fill out
 *      @asc: the additional sense code we'll fill out
 *      @ascq: the additional sense code qualifier we'll fill out
 *      @verbose: be verbose
 *
 *      Converts an ATA error into a SCSI error.  Fill out pointers to
 *      SK, ASC, and ASCQ bytes for later use in fixed or descriptor
 *      format sense blocks.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_to_sense_error(unsigned id, u8 drv_stat, u8 drv_err, u8 *sk, u8 *asc,
                        u8 *ascq, int verbose)
{
        int i;

        /* Based on the 3ware driver translation table */
        static const unsigned char sense_table[][4] = {
                /* BBD|ECC|ID|MAR */
                {0xd1,          ABORTED_COMMAND, 0x00, 0x00},   // Device busy                  Aborted command
                /* BBD|ECC|ID */
                {0xd0,          ABORTED_COMMAND, 0x00, 0x00},   // Device busy                  Aborted command
                /* ECC|MC|MARK */
                {0x61,          HARDWARE_ERROR, 0x00, 0x00},    // Device fault                 Hardware error
                /* ICRC|ABRT */         /* NB: ICRC & !ABRT is BBD */
                {0x84,          ABORTED_COMMAND, 0x47, 0x00},   // Data CRC error               SCSI parity error
                /* MC|ID|ABRT|TRK0|MARK */
                {0x37,          NOT_READY, 0x04, 0x00},         // Unit offline                 Not ready
                /* MCR|MARK */
                {0x09,          NOT_READY, 0x04, 0x00},         // Unrecovered disk error       Not ready
                /*  Bad address mark */
                {0x01,          MEDIUM_ERROR, 0x13, 0x00},      // Address mark not found       Address mark not found for data field
                /* TRK0 */
                {0x02,          HARDWARE_ERROR, 0x00, 0x00},    // Track 0 not found              Hardware error
                /* Abort & !ICRC */
                {0x04,          ABORTED_COMMAND, 0x00, 0x00},   // Aborted command              Aborted command
                /* Media change request */
                {0x08,          NOT_READY, 0x04, 0x00},         // Media change request   FIXME: faking offline
                /* SRV */
                {0x10,          ABORTED_COMMAND, 0x14, 0x00},   // ID not found                 Recorded entity not found
                /* Media change */
                {0x08,          NOT_READY, 0x04, 0x00},         // Media change           FIXME: faking offline
                /* ECC */
                {0x40,          MEDIUM_ERROR, 0x11, 0x04},      // Uncorrectable ECC error      Unrecovered read error
                /* BBD - block marked bad */
                {0x80,          MEDIUM_ERROR, 0x11, 0x04},      // Block marked bad               Medium error, unrecovered read error
                {0xFF, 0xFF, 0xFF, 0xFF}, // END mark
        };
        static const unsigned char stat_table[][4] = {
                /* Must be first because BUSY means no other bits valid */
                {0x80,          ABORTED_COMMAND, 0x47, 0x00},   // Busy, fake parity for now
                {0x20,          HARDWARE_ERROR,  0x00, 0x00},   // Device fault
                {0x08,          ABORTED_COMMAND, 0x47, 0x00},   // Timed out in xfer, fake parity for now
                {0x04,          RECOVERED_ERROR, 0x11, 0x00},   // Recovered ECC error    Medium error, recovered
                {0xFF, 0xFF, 0xFF, 0xFF}, // END mark
        };

        /*
         *      Is this an error we can process/parse
         */
        if (drv_stat & ATA_BUSY) {
                drv_err = 0;    /* Ignore the err bits, they're invalid */
        }

        if (drv_err) {
                /* Look for drv_err */
                for (i = 0; sense_table[i][0] != 0xFF; i++) {
                        /* Look for best matches first */
                        if ((sense_table[i][0] & drv_err) ==
                            sense_table[i][0]) {
                                *sk = sense_table[i][1];
                                *asc = sense_table[i][2];
                                *ascq = sense_table[i][3];
                                goto translate_done;
                        }
                }
                /* No immediate match */
                if (verbose)
                        printk(KERN_WARNING "ata%u: no sense translation for "
                               "error 0x%02x\n", id, drv_err);
        }

        /* Fall back to interpreting status bits */
        for (i = 0; stat_table[i][0] != 0xFF; i++) {
                if (stat_table[i][0] & drv_stat) {
                        *sk = stat_table[i][1];
                        *asc = stat_table[i][2];
                        *ascq = stat_table[i][3];
                        goto translate_done;
                }
        }
        /* No error?  Undecoded? */
        if (verbose)
                printk(KERN_WARNING "ata%u: no sense translation for "
                       "status: 0x%02x\n", id, drv_stat);

        /* We need a sensible error return here, which is tricky, and one
           that won't cause people to do things like return a disk wrongly */
        *sk = ABORTED_COMMAND;
        *asc = 0x00;
        *ascq = 0x00;

 translate_done:
        if (verbose)
                printk(KERN_ERR "ata%u: translated ATA stat/err 0x%02x/%02x "
                       "to SCSI SK/ASC/ASCQ 0x%x/%02x/%02x\n",
                       id, drv_stat, drv_err, *sk, *asc, *ascq);
        return;
}

/*
 *      ata_gen_ata_desc_sense - Generate check condition sense block.
 *      @qc: Command that completed.
 *
 *      This function is specific to the ATA descriptor format sense
 *      block specified for the ATA pass through commands.  Regardless
 *      of whether the command errored or not, return a sense
 *      block. Copy all controller registers into the sense
 *      block. Clear sense key, ASC & ASCQ if there is no error.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_gen_ata_desc_sense(struct ata_queued_cmd *qc)
{
        struct scsi_cmnd *cmd = qc->scsicmd;
        struct ata_taskfile *tf = &qc->result_tf;
        unsigned char *sb = cmd->sense_buffer;
        unsigned char *desc = sb + 8;
        int verbose = qc->ap->ops->error_handler == NULL;

        memset(sb, 0, SCSI_SENSE_BUFFERSIZE);

        cmd->result = (DRIVER_SENSE << 24) | SAM_STAT_CHECK_CONDITION;

        /*
         * Use ata_to_sense_error() to map status register bits
         * onto sense key, asc & ascq.
         */
        if (qc->err_mask ||
            tf->command & (ATA_BUSY | ATA_DF | ATA_ERR | ATA_DRQ)) {
                ata_to_sense_error(qc->ap->id, tf->command, tf->feature,
                                   &sb[1], &sb[2], &sb[3], verbose);
                sb[1] &= 0x0f;
        }

        /*
         * Sense data is current and format is descriptor.
         */
        sb[0] = 0x72;

        desc[0] = 0x09;

        /*
         * Set length of additional sense data.
         * Since we only populate descriptor 0, the total
         * length is the same (fixed) length as descriptor 0.
         */
        desc[1] = sb[7] = 14;

        /*
         * Copy registers into sense buffer.
         */
        desc[2] = 0x00;
        desc[3] = tf->feature;  /* == error reg */
        desc[5] = tf->nsect;
        desc[7] = tf->lbal;
        desc[9] = tf->lbam;
        desc[11] = tf->lbah;
        desc[12] = tf->device;
        desc[13] = tf->command; /* == status reg */

        /*
         * Fill in Extend bit, and the high order bytes
         * if applicable.
         */
        if (tf->flags & ATA_TFLAG_LBA48) {
                desc[2] |= 0x01;
                desc[4] = tf->hob_nsect;
                desc[6] = tf->hob_lbal;
                desc[8] = tf->hob_lbam;
                desc[10] = tf->hob_lbah;
        }
}

/**
 *      ata_gen_fixed_sense - generate a SCSI fixed sense block
 *      @qc: Command that we are erroring out
 *
 *      Leverage ata_to_sense_error() to give us the codes.  Fit our
 *      LBA in here if there's room.
 *
 *      LOCKING:
 *      inherited from caller
 */
void ata_gen_fixed_sense(struct ata_queued_cmd *qc)
{
        struct scsi_cmnd *cmd = qc->scsicmd;
        struct ata_taskfile *tf = &qc->result_tf;
        unsigned char *sb = cmd->sense_buffer;
        int verbose = qc->ap->ops->error_handler == NULL;

        memset(sb, 0, SCSI_SENSE_BUFFERSIZE);

        cmd->result = (DRIVER_SENSE << 24) | SAM_STAT_CHECK_CONDITION;

        /*
         * Use ata_to_sense_error() to map status register bits
         * onto sense key, asc & ascq.
         */
        if (qc->err_mask ||
            tf->command & (ATA_BUSY | ATA_DF | ATA_ERR | ATA_DRQ)) {
                ata_to_sense_error(qc->ap->id, tf->command, tf->feature,
                                   &sb[2], &sb[12], &sb[13], verbose);
                sb[2] &= 0x0f;
        }

        sb[0] = 0x70;
        sb[7] = 0x0a;

        if (tf->flags & ATA_TFLAG_LBA48) {
                /* TODO: find solution for LBA48 descriptors */
        }

        else if (tf->flags & ATA_TFLAG_LBA) {
                /* A small (28b) LBA will fit in the 32b info field */
                sb[0] |= 0x80;          /* set valid bit */
                sb[3] = tf->device & 0x0f;
                sb[4] = tf->lbah;
                sb[5] = tf->lbam;
                sb[6] = tf->lbal;
        }

        else {
                /* TODO: C/H/S */
        }
}

static void ata_scsi_sdev_config(struct scsi_device *sdev)
{
        sdev->use_10_for_rw = 1;
        sdev->use_10_for_ms = 1;
}

static void ata_scsi_dev_config(struct scsi_device *sdev,
                                struct ata_device *dev)
{
        unsigned int max_sectors;

        /* TODO: 2048 is an arbitrary number, not the
         * hardware maximum.  This should be increased to
         * 65534 when Jens Axboe's patch for dynamically
         * determining max_sectors is merged.
         */
        max_sectors = ATA_MAX_SECTORS;
        if (dev->flags & ATA_DFLAG_LBA48)
                max_sectors = ATA_MAX_SECTORS_LBA48;
        if (dev->max_sectors)
                max_sectors = dev->max_sectors;

        blk_queue_max_sectors(sdev->request_queue, max_sectors);

        /*
         * SATA DMA transfers must be multiples of 4 byte, so
         * we need to pad ATAPI transfers using an extra sg.
         * Decrement max hw segments accordingly.
         */
        if (dev->class == ATA_DEV_ATAPI) {
                request_queue_t *q = sdev->request_queue;
                blk_queue_max_hw_segments(q, q->max_hw_segments - 1);
        }

        if (dev->flags & ATA_DFLAG_NCQ) {
                int depth;

                depth = min(sdev->host->can_queue, ata_id_queue_depth(dev->id));
                depth = min(ATA_MAX_QUEUE - 1, depth);
                scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
        }
}

/**
 *      ata_scsi_slave_config - Set SCSI device attributes
 *      @sdev: SCSI device to examine
 *
 *      This is called before we actually start reading
 *      and writing to the device, to configure certain
 *      SCSI mid-layer behaviors.
 *
 *      LOCKING:
 *      Defined by SCSI layer.  We don't really care.
 */

int ata_scsi_slave_config(struct scsi_device *sdev)
{
        struct ata_port *ap = ata_shost_to_port(sdev->host);
        struct ata_device *dev = __ata_scsi_find_dev(ap, sdev);

        ata_scsi_sdev_config(sdev);

        blk_queue_max_phys_segments(sdev->request_queue, LIBATA_MAX_PRD);

        if (dev)
                ata_scsi_dev_config(sdev, dev);

        return 0;       /* scsi layer doesn't check return value, sigh */
}

/**
 *      ata_scsi_slave_destroy - SCSI device is about to be destroyed
 *      @sdev: SCSI device to be destroyed
 *
 *      @sdev is about to be destroyed for hot/warm unplugging.  If
 *      this unplugging was initiated by libata as indicated by NULL
 *      dev->sdev, this function doesn't have to do anything.
 *      Otherwise, SCSI layer initiated warm-unplug is in progress.
 *      Clear dev->sdev, schedule the device for ATA detach and invoke
 *      EH.
 *
 *      LOCKING:
 *      Defined by SCSI layer.  We don't really care.
 */
void ata_scsi_slave_destroy(struct scsi_device *sdev)
{
        struct ata_port *ap = ata_shost_to_port(sdev->host);
        unsigned long flags;
        struct ata_device *dev;

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

        spin_lock_irqsave(ap->lock, flags);
        dev = __ata_scsi_find_dev(ap, sdev);
        if (dev && dev->sdev) {
                /* SCSI device already in CANCEL state, no need to offline it */
                dev->sdev = NULL;
                dev->flags |= ATA_DFLAG_DETACH;
                ata_port_schedule_eh(ap);
        }
        spin_unlock_irqrestore(ap->lock, flags);
}

/**
 *      ata_scsi_change_queue_depth - SCSI callback for queue depth config
 *      @sdev: SCSI device to configure queue depth for
 *      @queue_depth: new queue depth
 *
 *      This is libata standard hostt->change_queue_depth callback.
 *      SCSI will call into this callback when user tries to set queue
 *      depth via sysfs.
 *
 *      LOCKING:
 *      SCSI layer (we don't care)
 *
 *      RETURNS:
 *      Newly configured queue depth.
 */
int ata_scsi_change_queue_depth(struct scsi_device *sdev, int queue_depth)
{
        struct ata_port *ap = ata_shost_to_port(sdev->host);
        struct ata_device *dev;
        int max_depth;

        if (queue_depth < 1)
                return sdev->queue_depth;

        dev = ata_scsi_find_dev(ap, sdev);
        if (!dev || !ata_dev_enabled(dev))
                return sdev->queue_depth;

        max_depth = min(sdev->host->can_queue, ata_id_queue_depth(dev->id));
        max_depth = min(ATA_MAX_QUEUE - 1, max_depth);
        if (queue_depth > max_depth)
                queue_depth = max_depth;

        scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, queue_depth);
        return queue_depth;
}

/**
 *      ata_scsi_start_stop_xlat - Translate SCSI START STOP UNIT command
 *      @qc: Storage for translated ATA taskfile
 *      @scsicmd: SCSI command to translate
 *
 *      Sets up an ATA taskfile to issue STANDBY (to stop) or READ VERIFY
 *      (to start). Perhaps these commands should be preceded by
 *      CHECK POWER MODE to see what power mode the device is already in.
 *      [See SAT revision 5 at www.t10.org]
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, non-zero on error.
 */

static unsigned int ata_scsi_start_stop_xlat(struct ata_queued_cmd *qc,
                                             const u8 *scsicmd)
{
        struct ata_taskfile *tf = &qc->tf;

        tf->flags |= ATA_TFLAG_DEVICE | ATA_TFLAG_ISADDR;
        tf->protocol = ATA_PROT_NODATA;
        if (scsicmd[1] & 0x1) {
                ;       /* ignore IMMED bit, violates sat-r05 */
        }
        if (scsicmd[4] & 0x2)
                goto invalid_fld;       /* LOEJ bit set not supported */
        if (((scsicmd[4] >> 4) & 0xf) != 0)
                goto invalid_fld;       /* power conditions not supported */
        if (scsicmd[4] & 0x1) {
                tf->nsect = 1;  /* 1 sector, lba=0 */

                if (qc->dev->flags & ATA_DFLAG_LBA) {
                        tf->flags |= ATA_TFLAG_LBA;

                        tf->lbah = 0x0;
                        tf->lbam = 0x0;
                        tf->lbal = 0x0;
                        tf->device |= ATA_LBA;
                } else {
                        /* CHS */
                        tf->lbal = 0x1; /* sect */
                        tf->lbam = 0x0; /* cyl low */
                        tf->lbah = 0x0; /* cyl high */
                }

                tf->command = ATA_CMD_VERIFY;   /* READ VERIFY */
        } else {
                tf->nsect = 0;  /* time period value (0 implies now) */
                tf->command = ATA_CMD_STANDBY;
                /* Consider: ATA STANDBY IMMEDIATE command */
        }
        /*
         * Standby and Idle condition timers could be implemented but that
         * would require libata to implement the Power condition mode page
         * and allow the user to change it. Changing mode pages requires
         * MODE SELECT to be implemented.
         */

        return 0;

invalid_fld:
        ata_scsi_set_sense(qc->scsicmd, ILLEGAL_REQUEST, 0x24, 0x0);
        /* "Invalid field in cbd" */
        return 1;
}


/**
 *      ata_scsi_flush_xlat - Translate SCSI SYNCHRONIZE CACHE command
 *      @qc: Storage for translated ATA taskfile
 *      @scsicmd: SCSI command to translate (ignored)
 *
 *      Sets up an ATA taskfile to issue FLUSH CACHE or
 *      FLUSH CACHE EXT.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, non-zero on error.
 */

static unsigned int ata_scsi_flush_xlat(struct ata_queued_cmd *qc, const u8 *scsicmd)
{
        struct ata_taskfile *tf = &qc->tf;

        tf->flags |= ATA_TFLAG_DEVICE;
        tf->protocol = ATA_PROT_NODATA;

        if ((qc->dev->flags & ATA_DFLAG_LBA48) &&
            (ata_id_has_flush_ext(qc->dev->id)))
                tf->command = ATA_CMD_FLUSH_EXT;
        else
                tf->command = ATA_CMD_FLUSH;

        return 0;
}

/**
 *      scsi_6_lba_len - Get LBA and transfer length
 *      @scsicmd: SCSI command to translate
 *
 *      Calculate LBA and transfer length for 6-byte commands.
 *
 *      RETURNS:
 *      @plba: the LBA
 *      @plen: the transfer length
 */

static void scsi_6_lba_len(const u8 *scsicmd, u64 *plba, u32 *plen)
{
        u64 lba = 0;
        u32 len = 0;

        VPRINTK("six-byte command\n");

        lba |= ((u64)scsicmd[2]) << 8;
        lba |= ((u64)scsicmd[3]);

        len |= ((u32)scsicmd[4]);

        *plba = lba;
        *plen = len;
}

/**
 *      scsi_10_lba_len - Get LBA and transfer length
 *      @scsicmd: SCSI command to translate
 *
 *      Calculate LBA and transfer length for 10-byte commands.
 *
 *      RETURNS:
 *      @plba: the LBA
 *      @plen: the transfer length
 */

static void scsi_10_lba_len(const u8 *scsicmd, u64 *plba, u32 *plen)
{
        u64 lba = 0;
        u32 len = 0;

        VPRINTK("ten-byte command\n");

        lba |= ((u64)scsicmd[2]) << 24;
        lba |= ((u64)scsicmd[3]) << 16;
        lba |= ((u64)scsicmd[4]) << 8;
        lba |= ((u64)scsicmd[5]);

        len |= ((u32)scsicmd[7]) << 8;
        len |= ((u32)scsicmd[8]);

        *plba = lba;
        *plen = len;
}

/**
 *      scsi_16_lba_len - Get LBA and transfer length
 *      @scsicmd: SCSI command to translate
 *
 *      Calculate LBA and transfer length for 16-byte commands.
 *
 *      RETURNS:
 *      @plba: the LBA
 *      @plen: the transfer length
 */

static void scsi_16_lba_len(const u8 *scsicmd, u64 *plba, u32 *plen)
{
        u64 lba = 0;
        u32 len = 0;

        VPRINTK("sixteen-byte command\n");

        lba |= ((u64)scsicmd[2]) << 56;
        lba |= ((u64)scsicmd[3]) << 48;
        lba |= ((u64)scsicmd[4]) << 40;
        lba |= ((u64)scsicmd[5]) << 32;
        lba |= ((u64)scsicmd[6]) << 24;
        lba |= ((u64)scsicmd[7]) << 16;
        lba |= ((u64)scsicmd[8]) << 8;
        lba |= ((u64)scsicmd[9]);

        len |= ((u32)scsicmd[10]) << 24;
        len |= ((u32)scsicmd[11]) << 16;
        len |= ((u32)scsicmd[12]) << 8;
        len |= ((u32)scsicmd[13]);

        *plba = lba;
        *plen = len;
}

/**
 *      ata_scsi_verify_xlat - Translate SCSI VERIFY command into an ATA one
 *      @qc: Storage for translated ATA taskfile
 *      @scsicmd: SCSI command to translate
 *
 *      Converts SCSI VERIFY command to an ATA READ VERIFY command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, non-zero on error.
 */

static unsigned int ata_scsi_verify_xlat(struct ata_queued_cmd *qc, const u8 *scsicmd)
{
        struct ata_taskfile *tf = &qc->tf;
        struct ata_device *dev = qc->dev;
        u64 dev_sectors = qc->dev->n_sectors;
        u64 block;
        u32 n_block;

        tf->flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        tf->protocol = ATA_PROT_NODATA;

        if (scsicmd[0] == VERIFY)
                scsi_10_lba_len(scsicmd, &block, &n_block);
        else if (scsicmd[0] == VERIFY_16)
                scsi_16_lba_len(scsicmd, &block, &n_block);
        else
                goto invalid_fld;

        if (!n_block)
                goto nothing_to_do;
        if (block >= dev_sectors)
                goto out_of_range;
        if ((block + n_block) > dev_sectors)
                goto out_of_range;

        if (dev->flags & ATA_DFLAG_LBA) {
                tf->flags |= ATA_TFLAG_LBA;

                if (lba_28_ok(block, n_block)) {
                        /* use LBA28 */
                        tf->command = ATA_CMD_VERIFY;
                        tf->device |= (block >> 24) & 0xf;
                } else if (lba_48_ok(block, n_block)) {
                        if (!(dev->flags & ATA_DFLAG_LBA48))
                                goto out_of_range;

                        /* use LBA48 */
                        tf->flags |= ATA_TFLAG_LBA48;
                        tf->command = ATA_CMD_VERIFY_EXT;

                        tf->hob_nsect = (n_block >> 8) & 0xff;

                        tf->hob_lbah = (block >> 40) & 0xff;
                        tf->hob_lbam = (block >> 32) & 0xff;
                        tf->hob_lbal = (block >> 24) & 0xff;
                } else
                        /* request too large even for LBA48 */
                        goto out_of_range;

                tf->nsect = n_block & 0xff;

                tf->lbah = (block >> 16) & 0xff;
                tf->lbam = (block >> 8) & 0xff;
                tf->lbal = block & 0xff;

                tf->device |= ATA_LBA;
        } else {
                /* CHS */
                u32 sect, head, cyl, track;

                if (!lba_28_ok(block, n_block))
                        goto out_of_range;

                /* Convert LBA to CHS */
                track = (u32)block / dev->sectors;
                cyl   = track / dev->heads;
                head  = track % dev->heads;
                sect  = (u32)block % dev->sectors + 1;

                DPRINTK("block %u track %u cyl %u head %u sect %u\n",
                        (u32)block, track, cyl, head, sect);

                /* Check whether the converted CHS can fit.
                   Cylinder: 0-65535
                   Head: 0-15
                   Sector: 1-255*/
                if ((cyl >> 16) || (head >> 4) || (sect >> 8) || (!sect))
                        goto out_of_range;

                tf->command = ATA_CMD_VERIFY;
                tf->nsect = n_block & 0xff; /* Sector count 0 means 256 sectors */
                tf->lbal = sect;
                tf->lbam = cyl;
                tf->lbah = cyl >> 8;
                tf->device |= head;
        }

        return 0;

invalid_fld:
        ata_scsi_set_sense(qc->scsicmd, ILLEGAL_REQUEST, 0x24, 0x0);
        /* "Invalid field in cbd" */
        return 1;

out_of_range:
        ata_scsi_set_sense(qc->scsicmd, ILLEGAL_REQUEST, 0x21, 0x0);
        /* "Logical Block Address out of range" */
        return 1;

nothing_to_do:
        qc->scsicmd->result = SAM_STAT_GOOD;
        return 1;
}

/**
 *      ata_scsi_rw_xlat - Translate SCSI r/w command into an ATA one
 *      @qc: Storage for translated ATA taskfile
 *      @scsicmd: SCSI command to translate
 *
 *      Converts any of six SCSI read/write commands into the
 *      ATA counterpart, including starting sector (LBA),
 *      sector count, and taking into account the device's LBA48
 *      support.
 *
 *      Commands %READ_6, %READ_10, %READ_16, %WRITE_6, %WRITE_10, and
 *      %WRITE_16 are currently supported.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, non-zero on error.
 */

static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, const u8 *scsicmd)
{
        struct ata_taskfile *tf = &qc->tf;
        struct ata_device *dev = qc->dev;
        u64 block;
        u32 n_block;

        qc->flags |= ATA_QCFLAG_IO;
        tf->flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;

        if (scsicmd[0] == WRITE_10 || scsicmd[0] == WRITE_6 ||
            scsicmd[0] == WRITE_16)
                tf->flags |= ATA_TFLAG_WRITE;

        /* Calculate the SCSI LBA, transfer length and FUA. */
        switch (scsicmd[0]) {
        case READ_10:
        case WRITE_10:
                scsi_10_lba_len(scsicmd, &block, &n_block);
                if (unlikely(scsicmd[1] & (1 << 3)))
                        tf->flags |= ATA_TFLAG_FUA;
                break;
        case READ_6:
        case WRITE_6:
                scsi_6_lba_len(scsicmd, &block, &n_block);

                /* for 6-byte r/w commands, transfer length 0
                 * means 256 blocks of data, not 0 block.
                 */
                if (!n_block)
                        n_block = 256;
                break;
        case READ_16:
        case WRITE_16:
                scsi_16_lba_len(scsicmd, &block, &n_block);
                if (unlikely(scsicmd[1] & (1 << 3)))
                        tf->flags |= ATA_TFLAG_FUA;
                break;
        default:
                DPRINTK("no-byte command\n");
                goto invalid_fld;
        }

        /* Check and compose ATA command */
        if (!n_block)
                /* For 10-byte and 16-byte SCSI R/W commands, transfer
                 * length 0 means transfer 0 block of data.
                 * However, for ATA R/W commands, sector count 0 means
                 * 256 or 65536 sectors, not 0 sectors as in SCSI.
                 *
                 * WARNING: one or two older ATA drives treat 0 as 0...
                 */
                goto nothing_to_do;

        if ((dev->flags & (ATA_DFLAG_PIO | ATA_DFLAG_NCQ)) == ATA_DFLAG_NCQ) {
                /* yay, NCQ */
                if (!lba_48_ok(block, n_block))
                        goto out_of_range;

                tf->protocol = ATA_PROT_NCQ;
                tf->flags |= ATA_TFLAG_LBA | ATA_TFLAG_LBA48;

                if (tf->flags & ATA_TFLAG_WRITE)
                        tf->command = ATA_CMD_FPDMA_WRITE;
                else
                        tf->command = ATA_CMD_FPDMA_READ;

                qc->nsect = n_block;

                tf->nsect = qc->tag << 3;
                tf->hob_feature = (n_block >> 8) & 0xff;
                tf->feature = n_block & 0xff;

                tf->hob_lbah = (block >> 40) & 0xff;
                tf->hob_lbam = (block >> 32) & 0xff;
                tf->hob_lbal = (block >> 24) & 0xff;
                tf->lbah = (block >> 16) & 0xff;
                tf->lbam = (block >> 8) & 0xff;
                tf->lbal = block & 0xff;

                tf->device = 1 << 6;
                if (tf->flags & ATA_TFLAG_FUA)
                        tf->device |= 1 << 7;
        } else if (dev->flags & ATA_DFLAG_LBA) {
                tf->flags |= ATA_TFLAG_LBA;

                if (lba_28_ok(block, n_block)) {
                        /* use LBA28 */
                        tf->device |= (block >> 24) & 0xf;
                } else if (lba_48_ok(block, n_block)) {
                        if (!(dev->flags & ATA_DFLAG_LBA48))
                                goto out_of_range;

                        /* use LBA48 */
                        tf->flags |= ATA_TFLAG_LBA48;

                        tf->hob_nsect = (n_block >> 8) & 0xff;

                        tf->hob_lbah = (block >> 40) & 0xff;
                        tf->hob_lbam = (block >> 32) & 0xff;
                        tf->hob_lbal = (block >> 24) & 0xff;
                } else
                        /* request too large even for LBA48 */
                        goto out_of_range;

                if (unlikely(ata_rwcmd_protocol(qc) < 0))
                        goto invalid_fld;

                qc->nsect = n_block;
                tf->nsect = n_block & 0xff;

                tf->lbah = (block >> 16) & 0xff;
                tf->lbam = (block >> 8) & 0xff;
                tf->lbal = block & 0xff;

                tf->device |= ATA_LBA;
        } else {
                /* CHS */
                u32 sect, head, cyl, track;

                /* The request -may- be too large for CHS addressing. */
                if (!lba_28_ok(block, n_block))
                        goto out_of_range;

                if (unlikely(ata_rwcmd_protocol(qc) < 0))
                        goto invalid_fld;

                /* Convert LBA to CHS */
                track = (u32)block / dev->sectors;
                cyl   = track / dev->heads;
                head  = track % dev->heads;
                sect  = (u32)block % dev->sectors + 1;

                DPRINTK("block %u track %u cyl %u head %u sect %u\n",
                        (u32)block, track, cyl, head, sect);

                /* Check whether the converted CHS can fit.
                   Cylinder: 0-65535
                   Head: 0-15
                   Sector: 1-255*/
                if ((cyl >> 16) || (head >> 4) || (sect >> 8) || (!sect))
                        goto out_of_range;

                qc->nsect = n_block;
                tf->nsect = n_block & 0xff; /* Sector count 0 means 256 sectors */
                tf->lbal = sect;
                tf->lbam = cyl;
                tf->lbah = cyl >> 8;
                tf->device |= head;
        }

        return 0;

invalid_fld:
        ata_scsi_set_sense(qc->scsicmd, ILLEGAL_REQUEST, 0x24, 0x0);
        /* "Invalid field in cbd" */
        return 1;

out_of_range:
        ata_scsi_set_sense(qc->scsicmd, ILLEGAL_REQUEST, 0x21, 0x0);
        /* "Logical Block Address out of range" */
        return 1;

nothing_to_do:
        qc->scsicmd->result = SAM_STAT_GOOD;
        return 1;
}

static void ata_scsi_qc_complete(struct ata_queued_cmd *qc)
{
        struct scsi_cmnd *cmd = qc->scsicmd;
        u8 *cdb = cmd->cmnd;
        int need_sense = (qc->err_mask != 0);

        /* We snoop the SET_FEATURES - Write Cache ON/OFF command, and
         * schedule EH_REVALIDATE operation to update the IDENTIFY DEVICE
         * cache
         */
        if (!need_sense && (qc->tf.command == ATA_CMD_SET_FEATURES) &&
            ((qc->tf.feature == SETFEATURES_WC_ON) ||
             (qc->tf.feature == SETFEATURES_WC_OFF))) {
                qc->ap->eh_info.action |= ATA_EH_REVALIDATE;
                ata_port_schedule_eh(qc->ap);
        }

        /* For ATA pass thru (SAT) commands, generate a sense block if
         * user mandated it or if there's an error.  Note that if we
         * generate because the user forced us to, a check condition
         * is generated and the ATA register values are returned
         * whether the command completed successfully or not. If there
         * was no error, SK, ASC and ASCQ will all be zero.
         */
        if (((cdb[0] == ATA_16) || (cdb[0] == ATA_12)) &&
            ((cdb[2] & 0x20) || need_sense)) {
                ata_gen_ata_desc_sense(qc);
        } else {
                if (!need_sense) {
                        cmd->result = SAM_STAT_GOOD;
                } else {
                        /* TODO: decide which descriptor format to use
                         * for 48b LBA devices and call that here
                         * instead of the fixed desc, which is only
                         * good for smaller LBA (and maybe CHS?)
                         * devices.
                         */
                        ata_gen_fixed_sense(qc);
                }
        }

        if (need_sense && !qc->ap->ops->error_handler)
                ata_dump_status(qc->ap->id, &qc->result_tf);

        qc->scsidone(cmd);

        ata_qc_free(qc);
}

/**
 *      ata_scmd_need_defer - Check whether we need to defer scmd
 *      @dev: ATA device to which the command is addressed
 *      @is_io: Is the command IO (and thus possibly NCQ)?
 *
 *      NCQ and non-NCQ commands cannot run together.  As upper layer
 *      only knows the queue depth, we are responsible for maintaining
 *      exclusion.  This function checks whether a new command can be
 *      issued to @dev.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      1 if deferring is needed, 0 otherwise.
 */
static int ata_scmd_need_defer(struct ata_device *dev, int is_io)
{
        struct ata_port *ap = dev->ap;

        if (!(dev->flags & ATA_DFLAG_NCQ))
                return 0;

        if (is_io) {
                if (!ata_tag_valid(ap->active_tag))
                        return 0;
        } else {
                if (!ata_tag_valid(ap->active_tag) && !ap->sactive)
                        return 0;
        }
        return 1;
}

/**
 *      ata_scsi_translate - Translate then issue SCSI command to ATA device
 *      @dev: ATA device to which the command is addressed
 *      @cmd: SCSI command to execute
 *      @done: SCSI command completion function
 *      @xlat_func: Actor which translates @cmd to an ATA taskfile
 *
 *      Our ->queuecommand() function has decided that the SCSI
 *      command issued can be directly translated into an ATA
 *      command, rather than handled internally.
 *
 *      This function sets up an ata_queued_cmd structure for the
 *      SCSI command, and sends that ata_queued_cmd to the hardware.
 *
 *      The xlat_func argument (actor) returns 0 if ready to execute
 *      ATA command, else 1 to finish translation. If 1 is returned
 *      then cmd->result (and possibly cmd->sense_buffer) are assumed
 *      to be set reflecting an error condition or clean (early)
 *      termination.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      0 on success, SCSI_ML_QUEUE_DEVICE_BUSY if the command
 *      needs to be deferred.
 */
static int ata_scsi_translate(struct ata_device *dev, struct scsi_cmnd *cmd,
                              void (*done)(struct scsi_cmnd *),
                              ata_xlat_func_t xlat_func)
{
        struct ata_queued_cmd *qc;
        u8 *scsicmd = cmd->cmnd;
        int is_io = xlat_func == ata_scsi_rw_xlat;

        VPRINTK("ENTER\n");

        if (unlikely(ata_scmd_need_defer(dev, is_io)))
                goto defer;

        qc = ata_scsi_qc_new(dev, cmd, done);
        if (!qc)
                goto err_mem;

        /* data is present; dma-map it */
        if (cmd->sc_data_direction == DMA_FROM_DEVICE ||
            cmd->sc_data_direction == DMA_TO_DEVICE) {
                if (unlikely(cmd->request_bufflen < 1)) {
                        ata_dev_printk(dev, KERN_WARNING,
                                       "WARNING: zero len r/w req\n");
                        goto err_did;
                }

                if (cmd->use_sg)
                        ata_sg_init(qc, cmd->request_buffer, cmd->use_sg);
                else
                        ata_sg_init_one(qc, cmd->request_buffer,
                                        cmd->request_bufflen);

                qc->dma_dir = cmd->sc_data_direction;
        }

        qc->complete_fn = ata_scsi_qc_complete;

        if (xlat_func(qc, scsicmd))
                goto early_finish;

        /* select device, send command to hardware */
        ata_qc_issue(qc);

        VPRINTK("EXIT\n");
        return 0;

early_finish:
        ata_qc_free(qc);
        done(cmd);
        DPRINTK("EXIT - early finish (good or error)\n");
        return 0;

err_did:
        ata_qc_free(qc);
err_mem:
        cmd->result = (DID_ERROR << 16);
        done(cmd);
        DPRINTK("EXIT - internal\n");
        return 0;

defer:
        DPRINTK("EXIT - defer\n");
        return SCSI_MLQUEUE_DEVICE_BUSY;
}

/**
 *      ata_scsi_rbuf_get - Map response buffer.
 *      @cmd: SCSI command containing buffer to be mapped.
 *      @buf_out: Pointer to mapped area.
 *
 *      Maps buffer contained within SCSI command @cmd.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Length of response buffer.
 */

static unsigned int ata_scsi_rbuf_get(struct scsi_cmnd *cmd, u8 **buf_out)
{
        u8 *buf;
        unsigned int buflen;

        if (cmd->use_sg) {
                struct scatterlist *sg;

                sg = (struct scatterlist *) cmd->request_buffer;
                buf = kmap_atomic(sg->page, KM_USER0) + sg->offset;
                buflen = sg->length;
        } else {
                buf = cmd->request_buffer;
                buflen = cmd->request_bufflen;
        }

        *buf_out = buf;
        return buflen;
}

/**
 *      ata_scsi_rbuf_put - Unmap response buffer.
 *      @cmd: SCSI command containing buffer to be unmapped.
 *      @buf: buffer to unmap
 *
 *      Unmaps response buffer contained within @cmd.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

static inline void ata_scsi_rbuf_put(struct scsi_cmnd *cmd, u8 *buf)
{
        if (cmd->use_sg) {
                struct scatterlist *sg;

                sg = (struct scatterlist *) cmd->request_buffer;
                kunmap_atomic(buf - sg->offset, KM_USER0);
        }
}

/**
 *      ata_scsi_rbuf_fill - wrapper for SCSI command simulators
 *      @args: device IDENTIFY data / SCSI command of interest.
 *      @actor: Callback hook for desired SCSI command simulator
 *
 *      Takes care of the hard work of simulating a SCSI command...
 *      Mapping the response buffer, calling the command's handler,
 *      and handling the handler's return value.  This return value
 *      indicates whether the handler wishes the SCSI command to be
 *      completed successfully (0), or not (in which case cmd->result
 *      and sense buffer are assumed to be set).
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

void ata_scsi_rbuf_fill(struct ata_scsi_args *args,
                        unsigned int (*actor) (struct ata_scsi_args *args,
                                           u8 *rbuf, unsigned int buflen))
{
        u8 *rbuf;
        unsigned int buflen, rc;
        struct scsi_cmnd *cmd = args->cmd;

        buflen = ata_scsi_rbuf_get(cmd, &rbuf);
        memset(rbuf, 0, buflen);
        rc = actor(args, rbuf, buflen);
        ata_scsi_rbuf_put(cmd, rbuf);

        if (rc == 0)
                cmd->result = SAM_STAT_GOOD;
        args->done(cmd);
}

/**
 *      ata_scsiop_inq_std - Simulate INQUIRY command
 *      @args: device IDENTIFY data / SCSI command of interest.
 *      @rbuf: Response buffer, to which simulated SCSI cmd output is sent.
 *      @buflen: Response buffer length.
 *
 *      Returns standard device identification data associated
 *      with non-VPD INQUIRY command output.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

unsigned int ata_scsiop_inq_std(struct ata_scsi_args *args, u8 *rbuf,
                               unsigned int buflen)
{
        u8 hdr[] = {
                TYPE_DISK,
                0,
                0x5,    /* claim SPC-3 version compatibility */
                2,
                95 - 4
        };

        /* set scsi removeable (RMB) bit per ata bit */
        if (ata_id_removeable(args->id))
                hdr[1] |= (1 << 7);

        VPRINTK("ENTER\n");

        memcpy(rbuf, hdr, sizeof(hdr));

        if (buflen > 35) {
                memcpy(&rbuf[8], "ATA     ", 8);
                ata_id_string(args->id, &rbuf[16], ATA_ID_PROD_OFS, 16);
                ata_id_string(args->id, &rbuf[32], ATA_ID_FW_REV_OFS, 4);
                if (rbuf[32] == 0 || rbuf[32] == ' ')
                        memcpy(&rbuf[32], "n/a ", 4);
        }

        if (buflen > 63) {
                const u8 versions[] = {
                        0x60,   /* SAM-3 (no version claimed) */

                        0x03,
                        0x20,   /* SBC-2 (no version claimed) */

                        0x02,
                        0x60    /* SPC-3 (no version claimed) */
                };

                memcpy(rbuf + 59, versions, sizeof(versions));
        }

        return 0;
}

/**
 *      ata_scsiop_inq_00 - Simulate INQUIRY VPD page 0, list of pages
 *      @args: device IDENTIFY data / SCSI command of interest.
 *      @rbuf: Response buffer, to which simulated SCSI cmd output is sent.
 *      @buflen: Response buffer length.
 *
 *      Returns list of inquiry VPD pages available.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

unsigned int ata_scsiop_inq_00(struct ata_scsi_args *args, u8 *rbuf,
                              unsigned int buflen)
{
        const u8 pages[] = {
                0x00,   /* page 0x00, this page */
                0x80,   /* page 0x80, unit serial no page */
                0x83    /* page 0x83, device ident page */
        };
        rbuf[3] = sizeof(pages);        /* number of supported VPD pages */

        if (buflen > 6)
                memcpy(rbuf + 4, pages, sizeof(pages));

        return 0;
}

/**
 *      ata_scsiop_inq_80 - Simulate INQUIRY VPD page 80, device serial number
 *      @args: device IDENTIFY data / SCSI command of interest.
 *      @rbuf: Response buffer, to which simulated SCSI cmd output is sent.
 *      @buflen: Response buffer length.
 *
 *      Returns ATA device serial number.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

unsigned int ata_scsiop_inq_80(struct ata_scsi_args *args, u8 *rbuf,
                              unsigned int buflen)
{
        const u8 hdr[] = {
                0,
                0x80,                   /* this page code */
                0,
                ATA_SERNO_LEN,          /* page len */
        };
        memcpy(rbuf, hdr, sizeof(hdr));

        if (buflen > (ATA_SERNO_LEN + 4 - 1))
                ata_id_string(args->id, (unsigned char *) &rbuf[4],
                              ATA_ID_SERNO_OFS, ATA_SERNO_LEN);

        return 0;
}

/**
 *      ata_scsiop_inq_83 - Simulate INQUIRY VPD page 83, device identity
 *      @args: device IDENTIFY data / SCSI command of interest.
 *      @rbuf: Response buffer, to which simulated SCSI cmd output is sent.
 *      @buflen: Response buffer length.
 *
 *      Yields two logical unit device identification designators:
 *       - vendor specific ASCII containing the ATA serial number
 *       - SAT defined "t10 vendor id based" containing ASCII vendor
 *         name ("ATA     "), model and serial numbers.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

unsigned int ata_scsiop_inq_83(struct ata_scsi_args *args, u8 *rbuf,
                              unsigned int buflen)
{
        int num;
        const int sat_model_serial_desc_len = 68;
        const int ata_model_byte_len = 40;

        rbuf[1] = 0x83;                 /* this page code */
        num = 4;

        if (buflen > (ATA_SERNO_LEN + num + 3)) {
                /* piv=0, assoc=lu, code_set=ACSII, designator=vendor */
                rbuf[num + 0] = 2;
                rbuf[num + 3] = ATA_SERNO_LEN;
                num += 4;
                ata_id_string(args->id, (unsigned char *) rbuf + num,
                              ATA_ID_SERNO_OFS, ATA_SERNO_LEN);
                num += ATA_SERNO_LEN;
        }
        if (buflen > (sat_model_serial_desc_len + num + 3)) {
                /* SAT defined lu model and serial numbers descriptor */
                /* piv=0, assoc=lu, code_set=ACSII, designator=t10 vendor id */
                rbuf[num + 0] = 2;
                rbuf[num + 1] = 1;
                rbuf[num + 3] = sat_model_serial_desc_len;
                num += 4;
                memcpy(rbuf + num, "ATA     ", 8);
                num += 8;
                ata_id_string(args->id, (unsigned char *) rbuf + num,
                              ATA_ID_PROD_OFS, ata_model_byte_len);
                num += ata_model_byte_len;
                ata_id_string(args->id, (unsigned char *) rbuf + num,
                              ATA_ID_SERNO_OFS, ATA_SERNO_LEN);
                num += ATA_SERNO_LEN;
        }
        rbuf[3] = num - 4;    /* page len (assume less than 256 bytes) */
        return 0;
}

/**
 *      ata_scsiop_noop - Command handler that simply returns success.
 *      @args: device IDENTIFY data / SCSI command of interest.
 *      @rbuf: Response buffer, to which simulated SCSI cmd output is sent.
 *      @buflen: Response buffer length.
 *
 *      No operation.  Simply returns success to caller, to indicate
 *      that the caller should successfully complete this SCSI command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

unsigned int ata_scsiop_noop(struct ata_scsi_args *args, u8 *rbuf,
                            unsigned int buflen)
{
        VPRINTK("ENTER\n");
        return 0;
}

/**
 *      ata_msense_push - Push data onto MODE SENSE data output buffer
 *      @ptr_io: (input/output) Location to store more output data
 *      @last: End of output data buffer
 *      @buf: Pointer to BLOB being added to output buffer
 *      @buflen: Length of BLOB
 *
 *      Store MODE SENSE data on an output buffer.
 *
 *      LOCKING:
 *      None.
 */

static void ata_msense_push(u8 **ptr_io, const u8 *last,
                            const u8 *buf, unsigned int buflen)
{
        u8 *ptr = *ptr_io;

        if ((ptr + buflen - 1) > last)
                return;

        memcpy(ptr, buf, buflen);

        ptr += buflen;

        *ptr_io = ptr;
}

/**
 *      ata_msense_caching - Simulate MODE SENSE caching info page
 *      @id: device IDENTIFY data
 *      @ptr_io: (input/output) Location to store more output data
 *      @last: End of output data buffer
 *
 *      Generate a caching info page, which conditionally indicates
 *      write caching to the SCSI layer, depending on device
 *      capabilities.
 *
 *      LOCKING:
 *      None.
 */

static unsigned int ata_msense_caching(u16 *id, u8 **ptr_io,
                                       const u8 *last)
{
        u8 page[CACHE_MPAGE_LEN];

        memcpy(page, def_cache_mpage, sizeof(page));
        if (ata_id_wcache_enabled(id))
                page[2] |= (1 << 2);    /* write cache enable */
        if (!ata_id_rahead_enabled(id))
                page[12] |= (1 << 5);   /* disable read ahead */

        ata_msense_push(ptr_io, last, page, sizeof(page));
        return sizeof(page);
}

/**
 *      ata_msense_ctl_mode - Simulate MODE SENSE control mode page
 *      @dev: Device associated with this MODE SENSE command
 *      @ptr_io: (input/output) Location to store more output data
 *      @last: End of output data buffer
 *
 *      Generate a generic MODE SENSE control mode page.
 *
 *      LOCKING:
 *      None.
 */

static unsigned int ata_msense_ctl_mode(u8 **ptr_io, const u8 *last)
{
        ata_msense_push(ptr_io, last, def_control_mpage,
                        sizeof(def_control_mpage));
        return sizeof(def_control_mpage);
}

/**
 *      ata_msense_rw_recovery - Simulate MODE SENSE r/w error recovery page
 *      @dev: Device associated with this MODE SENSE command
 *      @ptr_io: (input/output) Location to store more output data
 *      @last: End of output data buffer
 *
 *      Generate a generic MODE SENSE r/w error recovery page.
 *
 *      LOCKING:
 *      None.
 */

static unsigned int ata_msense_rw_recovery(u8 **ptr_io, const u8 *last)
{

        ata_msense_push(ptr_io, last, def_rw_recovery_mpage,
                        sizeof(def_rw_recovery_mpage));
        return sizeof(def_rw_recovery_mpage);
}

/*
 * We can turn this into a real blacklist if it's needed, for now just
 * blacklist any Maxtor BANC1G10 revision firmware
 */
static int ata_dev_supports_fua(u16 *id)
{
        unsigned char model[41], fw[9];

        if (!libata_fua)
                return 0;
        if (!ata_id_has_fua(id))
                return 0;

        ata_id_c_string(id, model, ATA_ID_PROD_OFS, sizeof(model));
        ata_id_c_string(id, fw, ATA_ID_FW_REV_OFS, sizeof(fw));

        if (strcmp(model, "Maxtor"))
                return 1;
        if (strcmp(fw, "BANC1G10"))
                return 1;

        return 0; /* blacklisted */
}

/**
 *      ata_scsiop_mode_sense - Simulate MODE SENSE 6, 10 commands
 *      @args: device IDENTIFY data / SCSI command of interest.
 *      @rbuf: Response buffer, to which simulated SCSI cmd output is sent.
 *      @buflen: Response buffer length.
 *
 *      Simulate MODE SENSE commands. Assume this is invoked for direct
 *      access devices (e.g. disks) only. There should be no block
 *      descriptor for other device types.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

unsigned int ata_scsiop_mode_sense(struct ata_scsi_args *args, u8 *rbuf,
                                  unsigned int buflen)
{
        struct ata_device *dev = args->dev;
        u8 *scsicmd = args->cmd->cmnd, *p, *last;
        const u8 sat_blk_desc[] = {
                0, 0, 0, 0,     /* number of blocks: sat unspecified */
                0,
                0, 0x2, 0x0     /* block length: 512 bytes */
        };
        u8 pg, spg;
        unsigned int ebd, page_control, six_byte, output_len, alloc_len, minlen;
        u8 dpofua;

        VPRINTK("ENTER\n");

        six_byte = (scsicmd[0] == MODE_SENSE);
        ebd = !(scsicmd[1] & 0x8);      /* dbd bit inverted == edb */
        /*
         * LLBA bit in msense(10) ignored (compliant)
         */

        page_control = scsicmd[2] >> 6;
        switch (page_control) {
        case 0: /* current */
                break;  /* supported */
        case 3: /* saved */
                goto saving_not_supp;
        case 1: /* changeable */
        case 2: /* defaults */
        default:
                goto invalid_fld;
        }

        if (six_byte) {
                output_len = 4 + (ebd ? 8 : 0);
                alloc_len = scsicmd[4];
        } else {
                output_len = 8 + (ebd ? 8 : 0);
                alloc_len = (scsicmd[7] << 8) + scsicmd[8];
        }
        minlen = (alloc_len < buflen) ? alloc_len : buflen;

        p = rbuf + output_len;
        last = rbuf + minlen - 1;

        pg = scsicmd[2] & 0x3f;
        spg = scsicmd[3];
        /*
         * No mode subpages supported (yet) but asking for _all_
         * subpages may be valid
         */
        if (spg && (spg != ALL_SUB_MPAGES))
                goto invalid_fld;

        switch(pg) {
        case RW_RECOVERY_MPAGE:
                output_len += ata_msense_rw_recovery(&p, last);
                break;

        case CACHE_MPAGE:
                output_len += ata_msense_caching(args->id, &p, last);
                break;

        case CONTROL_MPAGE: {
                output_len += ata_msense_ctl_mode(&p, last);
                break;
                }

        case ALL_MPAGES:
                output_len += ata_msense_rw_recovery(&p, last);
                output_len += ata_msense_caching(args->id, &p, last);
                output_len += ata_msense_ctl_mode(&p, last);
                break;

        default:                /* invalid page code */
                goto invalid_fld;
        }

        if (minlen < 1)
                return 0;

        dpofua = 0;
        if (ata_dev_supports_fua(args->id) && (dev->flags & ATA_DFLAG_LBA48) &&
            (!(dev->flags & ATA_DFLAG_PIO) || dev->multi_count))
                dpofua = 1 << 4;

        if (six_byte) {
                output_len--;
                rbuf[0] = output_len;
                if (minlen > 2)
                        rbuf[2] |= dpofua;
                if (ebd) {
                        if (minlen > 3)
                                rbuf[3] = sizeof(sat_blk_desc);
                        if (minlen > 11)
                                memcpy(rbuf + 4, sat_blk_desc,
                                       sizeof(sat_blk_desc));
                }
        } else {
                output_len -= 2;
                rbuf[0] = output_len >> 8;
                if (minlen > 1)
                        rbuf[1] = output_len;
                if (minlen > 3)
                        rbuf[3] |= dpofua;
                if (ebd) {
                        if (minlen > 7)
                                rbuf[7] = sizeof(sat_blk_desc);
                        if (minlen > 15)
                                memcpy(rbuf + 8, sat_blk_desc,
                                       sizeof(sat_blk_desc));
                }
        }
        return 0;

invalid_fld:
        ata_scsi_set_sense(args->cmd, ILLEGAL_REQUEST, 0x24, 0x0);
        /* "Invalid field in cbd" */
        return 1;

saving_not_supp:
        ata_scsi_set_sense(args->cmd, ILLEGAL_REQUEST, 0x39, 0x0);
         /* "Saving parameters not supported" */
        return 1;
}

/**
 *      ata_scsiop_read_cap - Simulate READ CAPACITY[ 16] commands
 *      @args: device IDENTIFY data / SCSI command of interest.
 *      @rbuf: Response buffer, to which simulated SCSI cmd output is sent.
 *      @buflen: Response buffer length.
 *
 *      Simulate READ CAPACITY commands.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

unsigned int ata_scsiop_read_cap(struct ata_scsi_args *args, u8 *rbuf,
                                unsigned int buflen)
{
        u64 n_sectors;
        u32 tmp;

        VPRINTK("ENTER\n");

        if (ata_id_has_lba(args->id)) {
                if (ata_id_has_lba48(args->id))
                        n_sectors = ata_id_u64(args->id, 100);
                else
                        n_sectors = ata_id_u32(args->id, 60);
        } else {
                /* CHS default translation */
                n_sectors = args->id[1] * args->id[3] * args->id[6];

                if (ata_id_current_chs_valid(args->id))
                        /* CHS current translation */
                        n_sectors = ata_id_u32(args->id, 57);
        }

        n_sectors--;            /* ATA TotalUserSectors - 1 */

        if (args->cmd->cmnd[0] == READ_CAPACITY) {
                if( n_sectors >= 0xffffffffULL )
                        tmp = 0xffffffff ;  /* Return max count on overflow */
                else
                        tmp = n_sectors ;

                /* sector count, 32-bit */
                rbuf[0] = tmp >> (8 * 3);
                rbuf[1] = tmp >> (8 * 2);
                rbuf[2] = tmp >> (8 * 1);
                rbuf[3] = tmp;

                /* sector size */
                tmp = ATA_SECT_SIZE;
                rbuf[6] = tmp >> 8;
                rbuf[7] = tmp;

        } else {
                /* sector count, 64-bit */
                tmp = n_sectors >> (8 * 4);
                rbuf[2] = tmp >> (8 * 3);
                rbuf[3] = tmp >> (8 * 2);
                rbuf[4] = tmp >> (8 * 1);
                rbuf[5] = tmp;
                tmp = n_sectors;
                rbuf[6] = tmp >> (8 * 3);
                rbuf[7] = tmp >> (8 * 2);
                rbuf[8] = tmp >> (8 * 1);
                rbuf[9] = tmp;

                /* sector size */
                tmp = ATA_SECT_SIZE;
                rbuf[12] = tmp >> 8;
                rbuf[13] = tmp;
        }

        return 0;
}

/**
 *      ata_scsiop_report_luns - Simulate REPORT LUNS command
 *      @args: device IDENTIFY data / SCSI command of interest.
 *      @rbuf: Response buffer, to which simulated SCSI cmd output is sent.
 *      @buflen: Response buffer length.
 *
 *      Simulate REPORT LUNS command.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

unsigned int ata_scsiop_report_luns(struct ata_scsi_args *args, u8 *rbuf,
                                   unsigned int buflen)
{
        VPRINTK("ENTER\n");
        rbuf[3] = 8;    /* just one lun, LUN 0, size 8 bytes */

        return 0;
}

/**
 *      ata_scsi_set_sense - Set SCSI sense data and status
 *      @cmd: SCSI request to be handled
 *      @sk: SCSI-defined sense key
 *      @asc: SCSI-defined additional sense code
 *      @ascq: SCSI-defined additional sense code qualifier
 *
 *      Helper function that builds a valid fixed format, current
 *      response code and the given sense key (sk), additional sense
 *      code (asc) and additional sense code qualifier (ascq) with
 *      a SCSI command status of %SAM_STAT_CHECK_CONDITION and
 *      DRIVER_SENSE set in the upper bits of scsi_cmnd::result .
 *
 *      LOCKING:
 *      Not required
 */

void ata_scsi_set_sense(struct scsi_cmnd *cmd, u8 sk, u8 asc, u8 ascq)
{
        cmd->result = (DRIVER_SENSE << 24) | SAM_STAT_CHECK_CONDITION;

        cmd->sense_buffer[0] = 0x70;    /* fixed format, current */
        cmd->sense_buffer[2] = sk;
        cmd->sense_buffer[7] = 18 - 8;  /* additional sense length */
        cmd->sense_buffer[12] = asc;
        cmd->sense_buffer[13] = ascq;
}

/**
 *      ata_scsi_badcmd - End a SCSI request with an error
 *      @cmd: SCSI request to be handled
 *      @done: SCSI command completion function
 *      @asc: SCSI-defined additional sense code
 *      @ascq: SCSI-defined additional sense code qualifier
 *
 *      Helper function that completes a SCSI command with
 *      %SAM_STAT_CHECK_CONDITION, with a sense key %ILLEGAL_REQUEST
 *      and the specified additional sense codes.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

void ata_scsi_badcmd(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *), u8 asc, u8 ascq)
{
        DPRINTK("ENTER\n");
        ata_scsi_set_sense(cmd, ILLEGAL_REQUEST, asc, ascq);

        done(cmd);
}

static void atapi_sense_complete(struct ata_queued_cmd *qc)
{
        if (qc->err_mask && ((qc->err_mask & AC_ERR_DEV) == 0)) {
                /* FIXME: not quite right; we don't want the
                 * translation of taskfile registers into
                 * a sense descriptors, since that's only
                 * correct for ATA, not ATAPI
                 */
                ata_gen_ata_desc_sense(qc);
        }

        qc->scsidone(qc->scsicmd);
        ata_qc_free(qc);
}

/* is it pointless to prefer PIO for "safety reasons"? */
static inline int ata_pio_use_silly(struct ata_port *ap)
{
        return (ap->flags & ATA_FLAG_PIO_DMA);
}

static void atapi_request_sense(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct scsi_cmnd *cmd = qc->scsicmd;

        DPRINTK("ATAPI request sense\n");

        /* FIXME: is this needed? */
        memset(cmd->sense_buffer, 0, sizeof(cmd->sense_buffer));

        ap->ops->tf_read(ap, &qc->tf);

        /* fill these in, for the case where they are -not- overwritten */
        cmd->sense_buffer[0] = 0x70;
        cmd->sense_buffer[2] = qc->tf.feature >> 4;

        ata_qc_reinit(qc);

        ata_sg_init_one(qc, cmd->sense_buffer, sizeof(cmd->sense_buffer));
        qc->dma_dir = DMA_FROM_DEVICE;

        memset(&qc->cdb, 0, qc->dev->cdb_len);
        qc->cdb[0] = REQUEST_SENSE;
        qc->cdb[4] = SCSI_SENSE_BUFFERSIZE;

        qc->tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        qc->tf.command = ATA_CMD_PACKET;

        if (ata_pio_use_silly(ap)) {
                qc->tf.protocol = ATA_PROT_ATAPI_DMA;
                qc->tf.feature |= ATAPI_PKT_DMA;
        } else {
                qc->tf.protocol = ATA_PROT_ATAPI;
                qc->tf.lbam = (8 * 1024) & 0xff;
                qc->tf.lbah = (8 * 1024) >> 8;
        }
        qc->nbytes = SCSI_SENSE_BUFFERSIZE;

        qc->complete_fn = atapi_sense_complete;

        ata_qc_issue(qc);

        DPRINTK("EXIT\n");
}

static void atapi_qc_complete(struct ata_queued_cmd *qc)
{
        struct scsi_cmnd *cmd = qc->scsicmd;
        unsigned int err_mask = qc->err_mask;

        VPRINTK("ENTER, err_mask 0x%X\n", err_mask);

        /* handle completion from new EH */
        if (unlikely(qc->ap->ops->error_handler &&
                     (err_mask || qc->flags & ATA_QCFLAG_SENSE_VALID))) {

                if (!(qc->flags & ATA_QCFLAG_SENSE_VALID)) {
                        /* FIXME: not quite right; we don't want the
                         * translation of taskfile registers into a
                         * sense descriptors, since that's only
                         * correct for ATA, not ATAPI
                         */
                        ata_gen_ata_desc_sense(qc);
                }

                qc->scsicmd->result = SAM_STAT_CHECK_CONDITION;
                qc->scsidone(cmd);
                ata_qc_free(qc);
                return;
        }

        /* successful completion or old EH failure path */
        if (unlikely(err_mask & AC_ERR_DEV)) {
                cmd->result = SAM_STAT_CHECK_CONDITION;
                atapi_request_sense(qc);
                return;
        } else if (unlikely(err_mask)) {
                /* FIXME: not quite right; we don't want the
                 * translation of taskfile registers into
                 * a sense descriptors, since that's only
                 * correct for ATA, not ATAPI
                 */
                ata_gen_ata_desc_sense(qc);
        } else {
                u8 *scsicmd = cmd->cmnd;

                if ((scsicmd[0] == INQUIRY) && ((scsicmd[1] & 0x03) == 0)) {
                        u8 *buf = NULL;
                        unsigned int buflen;

                        buflen = ata_scsi_rbuf_get(cmd, &buf);

        /* ATAPI devices typically report zero for their SCSI version,
         * and sometimes deviate from the spec WRT response data
         * format.  If SCSI version is reported as zero like normal,
         * then we make the following fixups:  1) Fake MMC-5 version,
         * to indicate to the Linux scsi midlayer this is a modern
         * device.  2) Ensure response data format / ATAPI information
         * are always correct.
         */
                        if (buf[2] == 0) {
                                buf[2] = 0x5;
                                buf[3] = 0x32;
                        }

                        ata_scsi_rbuf_put(cmd, buf);
                }

                cmd->result = SAM_STAT_GOOD;
        }

        qc->scsidone(cmd);
        ata_qc_free(qc);
}
/**
 *      atapi_xlat - Initialize PACKET taskfile
 *      @qc: command structure to be initialized
 *      @scsicmd: SCSI CDB associated with this PACKET command
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Zero on success, non-zero on failure.
 */

static unsigned int atapi_xlat(struct ata_queued_cmd *qc, const u8 *scsicmd)
{
        struct scsi_cmnd *cmd = qc->scsicmd;
        struct ata_device *dev = qc->dev;
        int using_pio = (dev->flags & ATA_DFLAG_PIO);
        int nodata = (cmd->sc_data_direction == DMA_NONE);

        if (!using_pio)
                /* Check whether ATAPI DMA is safe */
                if (ata_check_atapi_dma(qc))
                        using_pio = 1;

        memcpy(&qc->cdb, scsicmd, dev->cdb_len);

        qc->complete_fn = atapi_qc_complete;

        qc->tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        if (cmd->sc_data_direction == DMA_TO_DEVICE) {
                qc->tf.flags |= ATA_TFLAG_WRITE;
                DPRINTK("direction: write\n");
        }

        qc->tf.command = ATA_CMD_PACKET;

        /* no data, or PIO data xfer */
        if (using_pio || nodata) {
                if (nodata)
                        qc->tf.protocol = ATA_PROT_ATAPI_NODATA;
                else
                        qc->tf.protocol = ATA_PROT_ATAPI;
                qc->tf.lbam = (8 * 1024) & 0xff;
                qc->tf.lbah = (8 * 1024) >> 8;
        }

        /* DMA data xfer */
        else {
                qc->tf.protocol = ATA_PROT_ATAPI_DMA;
                qc->tf.feature |= ATAPI_PKT_DMA;

                if (atapi_dmadir && (cmd->sc_data_direction != DMA_TO_DEVICE))
                        /* some SATA bridges need us to indicate data xfer direction */
                        qc->tf.feature |= ATAPI_DMADIR;
        }

        qc->nbytes = cmd->request_bufflen;

        return 0;
}

static struct ata_device * ata_find_dev(struct ata_port *ap, int id)
{
        if (likely(id < ATA_MAX_DEVICES))
                return &ap->device[id];
        return NULL;
}

static struct ata_device * __ata_scsi_find_dev(struct ata_port *ap,
                                        const struct scsi_device *scsidev)
{
        /* skip commands not addressed to targets we simulate */
        if (unlikely(scsidev->channel || scsidev->lun))
                return NULL;

        return ata_find_dev(ap, scsidev->id);
}

/**
 *      ata_scsi_dev_enabled - determine if device is enabled
 *      @dev: ATA device
 *
 *      Determine if commands should be sent to the specified device.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      0 if commands are not allowed / 1 if commands are allowed
 */

static int ata_scsi_dev_enabled(struct ata_device *dev)
{
        if (unlikely(!ata_dev_enabled(dev)))
                return 0;

        if (!atapi_enabled || (dev->ap->flags & ATA_FLAG_NO_ATAPI)) {
                if (unlikely(dev->class == ATA_DEV_ATAPI)) {
                        ata_dev_printk(dev, KERN_WARNING,
                                       "WARNING: ATAPI is %s, device ignored.\n",
                                       atapi_enabled ? "not supported with this driver" : "disabled");
                        return 0;
                }
        }

        return 1;
}

/**
 *      ata_scsi_find_dev - lookup ata_device from scsi_cmnd
 *      @ap: ATA port to which the device is attached
 *      @scsidev: SCSI device from which we derive the ATA device
 *
 *      Given various information provided in struct scsi_cmnd,
 *      map that onto an ATA bus, and using that mapping
 *      determine which ata_device is associated with the
 *      SCSI command to be sent.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Associated ATA device, or %NULL if not found.
 */
static struct ata_device *
ata_scsi_find_dev(struct ata_port *ap, const struct scsi_device *scsidev)
{
        struct ata_device *dev = __ata_scsi_find_dev(ap, scsidev);

        if (unlikely(!dev || !ata_scsi_dev_enabled(dev)))
                return NULL;

        return dev;
}

/*
 *      ata_scsi_map_proto - Map pass-thru protocol value to taskfile value.
 *      @byte1: Byte 1 from pass-thru CDB.
 *
 *      RETURNS:
 *      ATA_PROT_UNKNOWN if mapping failed/unimplemented, protocol otherwise.
 */
static u8
ata_scsi_map_proto(u8 byte1)
{
        switch((byte1 & 0x1e) >> 1) {
                case 3:         /* Non-data */
                        return ATA_PROT_NODATA;

                case 6:         /* DMA */
                        return ATA_PROT_DMA;

                case 4:         /* PIO Data-in */
                case 5:         /* PIO Data-out */
                        return ATA_PROT_PIO;

                case 10:        /* Device Reset */
                case 0:         /* Hard Reset */
                case 1:         /* SRST */
                case 2:         /* Bus Idle */
                case 7:         /* Packet */
                case 8:         /* DMA Queued */
                case 9:         /* Device Diagnostic */
                case 11:        /* UDMA Data-in */
                case 12:        /* UDMA Data-Out */
                case 13:        /* FPDMA */
                default:        /* Reserved */
                        break;
        }

        return ATA_PROT_UNKNOWN;
}

/**
 *      ata_scsi_pass_thru - convert ATA pass-thru CDB to taskfile
 *      @qc: command structure to be initialized
 *      @scsicmd: SCSI command to convert
 *
 *      Handles either 12 or 16-byte versions of the CDB.
 *
 *      RETURNS:
 *      Zero on success, non-zero on failure.
 */
static unsigned int
ata_scsi_pass_thru(struct ata_queued_cmd *qc, const u8 *scsicmd)
{
        struct ata_taskfile *tf = &(qc->tf);
        struct scsi_cmnd *cmd = qc->scsicmd;
        struct ata_device *dev = qc->dev;

        if ((tf->protocol = ata_scsi_map_proto(scsicmd[1])) == ATA_PROT_UNKNOWN)
                goto invalid_fld;

        /* We may not issue DMA commands if no DMA mode is set */
        if (tf->protocol == ATA_PROT_DMA && dev->dma_mode == 0)
                goto invalid_fld;

        if (scsicmd[1] & 0xe0)
                /* PIO multi not supported yet */
                goto invalid_fld;

        /*
         * 12 and 16 byte CDBs use different offsets to
         * provide the various register values.
         */
        if (scsicmd[0] == ATA_16) {
                /*
                 * 16-byte CDB - may contain extended commands.
                 *
                 * If that is the case, copy the upper byte register values.
                 */
                if (scsicmd[1] & 0x01) {
                        tf->hob_feature = scsicmd[3];
                        tf->hob_nsect = scsicmd[5];
                        tf->hob_lbal = scsicmd[7];
                        tf->hob_lbam = scsicmd[9];
                        tf->hob_lbah = scsicmd[11];
                        tf->flags |= ATA_TFLAG_LBA48;
                } else
                        tf->flags &= ~ATA_TFLAG_LBA48;

                /*
                 * Always copy low byte, device and command registers.
                 */
                tf->feature = scsicmd[4];
                tf->nsect = scsicmd[6];
                tf->lbal = scsicmd[8];
                tf->lbam = scsicmd[10];
                tf->lbah = scsicmd[12];
                tf->device = scsicmd[13];
                tf->command = scsicmd[14];
        } else {
                /*
                 * 12-byte CDB - incapable of extended commands.
                 */
                tf->flags &= ~ATA_TFLAG_LBA48;

                tf->feature = scsicmd[3];
                tf->nsect = scsicmd[4];
                tf->lbal = scsicmd[5];
                tf->lbam = scsicmd[6];
                tf->lbah = scsicmd[7];
                tf->device = scsicmd[8];
                tf->command = scsicmd[9];
        }
        /*
         * If slave is possible, enforce correct master/slave bit
        */
        if (qc->ap->flags & ATA_FLAG_SLAVE_POSS)
                tf->device = qc->dev->devno ?
                        tf->device | ATA_DEV1 : tf->device & ~ATA_DEV1;

        /*
         * Filter SET_FEATURES - XFER MODE command -- otherwise,
         * SET_FEATURES - XFER MODE must be preceded/succeeded
         * by an update to hardware-specific registers for each
         * controller (i.e. the reason for ->set_piomode(),
         * ->set_dmamode(), and ->post_set_mode() hooks).
         */
        if ((tf->command == ATA_CMD_SET_FEATURES)
         && (tf->feature == SETFEATURES_XFER))
                goto invalid_fld;

        /*
         * Set flags so that all registers will be written,
         * and pass on write indication (used for PIO/DMA
         * setup.)
         */
        tf->flags |= (ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE);

        if (cmd->sc_data_direction == DMA_TO_DEVICE)
                tf->flags |= ATA_TFLAG_WRITE;

        /*
         * Set transfer length.
         *
         * TODO: find out if we need to do more here to
         *       cover scatter/gather case.
         */
        qc->nsect = cmd->request_bufflen / ATA_SECT_SIZE;

        /* request result TF */
        qc->flags |= ATA_QCFLAG_RESULT_TF;

        return 0;

 invalid_fld:
        ata_scsi_set_sense(qc->scsicmd, ILLEGAL_REQUEST, 0x24, 0x00);
        /* "Invalid field in cdb" */
        return 1;
}

/**
 *      ata_get_xlat_func - check if SCSI to ATA translation is possible
 *      @dev: ATA device
 *      @cmd: SCSI command opcode to consider
 *
 *      Look up the SCSI command given, and determine whether the
 *      SCSI command is to be translated or simulated.
 *
 *      RETURNS:
 *      Pointer to translation function if possible, %NULL if not.
 */

static inline ata_xlat_func_t ata_get_xlat_func(struct ata_device *dev, u8 cmd)
{
        switch (cmd) {
        case READ_6:
        case READ_10:
        case READ_16:

        case WRITE_6:
        case WRITE_10:
        case WRITE_16:
                return ata_scsi_rw_xlat;

        case SYNCHRONIZE_CACHE:
                if (ata_try_flush_cache(dev))
                        return ata_scsi_flush_xlat;
                break;

        case VERIFY:
        case VERIFY_16:
                return ata_scsi_verify_xlat;

        case ATA_12:
        case ATA_16:
                return ata_scsi_pass_thru;

        case START_STOP:
                return ata_scsi_start_stop_xlat;
        }

        return NULL;
}

/**
 *      ata_scsi_dump_cdb - dump SCSI command contents to dmesg
 *      @ap: ATA port to which the command was being sent
 *      @cmd: SCSI command to dump
 *
 *      Prints the contents of a SCSI command via printk().
 */

static inline void ata_scsi_dump_cdb(struct ata_port *ap,
                                     struct scsi_cmnd *cmd)
{
#ifdef ATA_DEBUG
        struct scsi_device *scsidev = cmd->device;
        u8 *scsicmd = cmd->cmnd;

        DPRINTK("CDB (%u:%d,%d,%d) %02x %02x %02x %02x %02x %02x %02x %02x %02x\n",
                ap->id,
                scsidev->channel, scsidev->id, scsidev->lun,
                scsicmd[0], scsicmd[1], scsicmd[2], scsicmd[3],
                scsicmd[4], scsicmd[5], scsicmd[6], scsicmd[7],
                scsicmd[8]);
#endif
}

static inline int __ata_scsi_queuecmd(struct scsi_cmnd *cmd,
                                      void (*done)(struct scsi_cmnd *),
                                      struct ata_device *dev)
{
        int rc = 0;

        if (dev->class == ATA_DEV_ATA) {
                ata_xlat_func_t xlat_func = ata_get_xlat_func(dev,
                                                              cmd->cmnd[0]);

                if (xlat_func)
                        rc = ata_scsi_translate(dev, cmd, done, xlat_func);
                else
                        ata_scsi_simulate(dev, cmd, done);
        } else
                rc = ata_scsi_translate(dev, cmd, done, atapi_xlat);

        return rc;
}

/**
 *      ata_scsi_queuecmd - Issue SCSI cdb to libata-managed device
 *      @cmd: SCSI command to be sent
 *      @done: Completion function, called when command is complete
 *
 *      In some cases, this function translates SCSI commands into
 *      ATA taskfiles, and queues the taskfiles to be sent to
 *      hardware.  In other cases, this function simulates a
 *      SCSI device by evaluating and responding to certain
 *      SCSI commands.  This creates the overall effect of
 *      ATA and ATAPI devices appearing as SCSI devices.
 *
 *      LOCKING:
 *      Releases scsi-layer-held lock, and obtains host_set lock.
 *
 *      RETURNS:
 *      Return value from __ata_scsi_queuecmd() if @cmd can be queued,
 *      0 otherwise.
 */
int ata_scsi_queuecmd(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *))
{
        struct ata_port *ap;
        struct ata_device *dev;
        struct scsi_device *scsidev = cmd->device;
        struct Scsi_Host *shost = scsidev->host;
        int rc = 0;

        ap = ata_shost_to_port(shost);

        spin_unlock(shost->host_lock);
        spin_lock(ap->lock);

        ata_scsi_dump_cdb(ap, cmd);

        dev = ata_scsi_find_dev(ap, scsidev);
        if (likely(dev))
                rc = __ata_scsi_queuecmd(cmd, done, dev);
        else {
                cmd->result = (DID_BAD_TARGET << 16);
                done(cmd);
        }

        spin_unlock(ap->lock);
        spin_lock(shost->host_lock);
        return rc;
}

/**
 *      ata_scsi_simulate - simulate SCSI command on ATA device
 *      @dev: the target device
 *      @cmd: SCSI command being sent to device.
 *      @done: SCSI command completion function.
 *
 *      Interprets and directly executes a select list of SCSI commands
 *      that can be handled internally.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

void ata_scsi_simulate(struct ata_device *dev, struct scsi_cmnd *cmd,
                      void (*done)(struct scsi_cmnd *))
{
        struct ata_scsi_args args;
        const u8 *scsicmd = cmd->cmnd;

        args.dev = dev;
        args.id = dev->id;
        args.cmd = cmd;
        args.done = done;

        switch(scsicmd[0]) {
                /* no-op's, complete with success */
                case SYNCHRONIZE_CACHE:
                case REZERO_UNIT:
                case SEEK_6:
                case SEEK_10:
                case TEST_UNIT_READY:
                case FORMAT_UNIT:               /* FIXME: correct? */
                case SEND_DIAGNOSTIC:           /* FIXME: correct? */
                        ata_scsi_rbuf_fill(&args, ata_scsiop_noop);
                        break;

                case INQUIRY:
                        if (scsicmd[1] & 2)                /* is CmdDt set?  */
                                ata_scsi_invalid_field(cmd, done);
                        else if ((scsicmd[1] & 1) == 0)    /* is EVPD clear? */
                                ata_scsi_rbuf_fill(&args, ata_scsiop_inq_std);
                        else if (scsicmd[2] == 0x00)
                                ata_scsi_rbuf_fill(&args, ata_scsiop_inq_00);
                        else if (scsicmd[2] == 0x80)
                                ata_scsi_rbuf_fill(&args, ata_scsiop_inq_80);
                        else if (scsicmd[2] == 0x83)
                                ata_scsi_rbuf_fill(&args, ata_scsiop_inq_83);
                        else
                                ata_scsi_invalid_field(cmd, done);
                        break;

                case MODE_SENSE:
                case MODE_SENSE_10:
                        ata_scsi_rbuf_fill(&args, ata_scsiop_mode_sense);
                        break;

                case MODE_SELECT:       /* unconditionally return */
                case MODE_SELECT_10:    /* bad-field-in-cdb */
                        ata_scsi_invalid_field(cmd, done);
                        break;

                case READ_CAPACITY:
                        ata_scsi_rbuf_fill(&args, ata_scsiop_read_cap);
                        break;

                case SERVICE_ACTION_IN:
                        if ((scsicmd[1] & 0x1f) == SAI_READ_CAPACITY_16)
                                ata_scsi_rbuf_fill(&args, ata_scsiop_read_cap);
                        else
                                ata_scsi_invalid_field(cmd, done);
                        break;

                case REPORT_LUNS:
                        ata_scsi_rbuf_fill(&args, ata_scsiop_report_luns);
                        break;

                /* mandatory commands we haven't implemented yet */
                case REQUEST_SENSE:

                /* all other commands */
                default:
                        ata_scsi_set_sense(cmd, ILLEGAL_REQUEST, 0x20, 0x0);
                        /* "Invalid command operation code" */
                        done(cmd);
                        break;
        }
}

void ata_scsi_scan_host(struct ata_port *ap)
{
        unsigned int i;

        if (ap->flags & ATA_FLAG_DISABLED)
                return;

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

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

                sdev = __scsi_add_device(ap->host, 0, i, 0, NULL);
                if (!IS_ERR(sdev)) {
                        dev->sdev = sdev;
                        scsi_device_put(sdev);
                }
        }
}

/**
 *      ata_scsi_offline_dev - offline attached SCSI device
 *      @dev: ATA device to offline attached SCSI device for
 *
 *      This function is called from ata_eh_hotplug() and responsible
 *      for taking the SCSI device attached to @dev offline.  This
 *      function is called with host_set lock which protects dev->sdev
 *      against clearing.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      1 if attached SCSI device exists, 0 otherwise.
 */
int ata_scsi_offline_dev(struct ata_device *dev)
{
        if (dev->sdev) {
                scsi_device_set_state(dev->sdev, SDEV_OFFLINE);
                return 1;
        }
        return 0;
}

/**
 *      ata_scsi_remove_dev - remove attached SCSI device
 *      @dev: ATA device to remove attached SCSI device for
 *
 *      This function is called from ata_eh_scsi_hotplug() and
 *      responsible for removing the SCSI device attached to @dev.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 */
static void ata_scsi_remove_dev(struct ata_device *dev)
{
        struct ata_port *ap = dev->ap;
        struct scsi_device *sdev;
        unsigned long flags;

        /* Alas, we need to grab scan_mutex to ensure SCSI device
         * state doesn't change underneath us and thus
         * scsi_device_get() always succeeds.  The mutex locking can
         * be removed if there is __scsi_device_get() interface which
         * increments reference counts regardless of device state.
         */
        mutex_lock(&ap->host->scan_mutex);
        spin_lock_irqsave(ap->lock, flags);

        /* clearing dev->sdev is protected by host_set lock */
        sdev = dev->sdev;
        dev->sdev = NULL;

        if (sdev) {
                /* If user initiated unplug races with us, sdev can go
                 * away underneath us after the host_set lock and
                 * scan_mutex are released.  Hold onto it.
                 */
                if (scsi_device_get(sdev) == 0) {
                        /* The following ensures the attached sdev is
                         * offline on return from ata_scsi_offline_dev()
                         * regardless it wins or loses the race
                         * against this function.
                         */
                        scsi_device_set_state(sdev, SDEV_OFFLINE);
                } else {
                        WARN_ON(1);
                        sdev = NULL;
                }
        }

        spin_unlock_irqrestore(ap->lock, flags);
        mutex_unlock(&ap->host->scan_mutex);

        if (sdev) {
                ata_dev_printk(dev, KERN_INFO, "detaching (SCSI %s)\n",
                               sdev->sdev_gendev.bus_id);

                scsi_remove_device(sdev);
                scsi_device_put(sdev);
        }
}

/**
 *      ata_scsi_hotplug - SCSI part of hotplug
 *      @data: Pointer to ATA port to perform SCSI hotplug on
 *
 *      Perform SCSI part of hotplug.  It's executed from a separate
 *      workqueue after EH completes.  This is necessary because SCSI
 *      hot plugging requires working EH and hot unplugging is
 *      synchronized with hot plugging with a mutex.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 */
void ata_scsi_hotplug(void *data)
{
        struct ata_port *ap = data;
        int i;

        if (ap->flags & ATA_FLAG_UNLOADING) {
                DPRINTK("ENTER/EXIT - unloading\n");
                return;
        }

        DPRINTK("ENTER\n");

        /* unplug detached devices */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *dev = &ap->device[i];
                unsigned long flags;

                if (!(dev->flags & ATA_DFLAG_DETACHED))
                        continue;

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

                ata_scsi_remove_dev(dev);
        }

        /* scan for new ones */
        ata_scsi_scan_host(ap);

        /* If we scanned while EH was in progress, scan would have
         * failed silently.  Requeue if there are enabled but
         * unattached devices.
         */
        for (i = 0; i < ATA_MAX_DEVICES; i++) {
                struct ata_device *dev = &ap->device[i];
                if (ata_dev_enabled(dev) && !dev->sdev) {
                        queue_delayed_work(ata_aux_wq, &ap->hotplug_task, HZ);
                        break;
                }
        }

        DPRINTK("EXIT\n");
}

/**
 *      ata_scsi_user_scan - indication for user-initiated bus scan
 *      @shost: SCSI host to scan
 *      @channel: Channel to scan
 *      @id: ID to scan
 *      @lun: LUN to scan
 *
 *      This function is called when user explicitly requests bus
 *      scan.  Set probe pending flag and invoke EH.
 *
 *      LOCKING:
 *      SCSI layer (we don't care)
 *
 *      RETURNS:
 *      Zero.
 */
static int ata_scsi_user_scan(struct Scsi_Host *shost, unsigned int channel,
                              unsigned int id, unsigned int lun)
{
        struct ata_port *ap = ata_shost_to_port(shost);
        unsigned long flags;
        int rc = 0;

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

        if ((channel != SCAN_WILD_CARD && channel != 0) ||
            (lun != SCAN_WILD_CARD && lun != 0))
                return -EINVAL;

        spin_lock_irqsave(ap->lock, flags);

        if (id == SCAN_WILD_CARD) {
                ap->eh_info.probe_mask |= (1 << ATA_MAX_DEVICES) - 1;
                ap->eh_info.action |= ATA_EH_SOFTRESET;
        } else {
                struct ata_device *dev = ata_find_dev(ap, id);

                if (dev) {
                        ap->eh_info.probe_mask |= 1 << dev->devno;
                        ap->eh_info.action |= ATA_EH_SOFTRESET;
                } else
                        rc = -EINVAL;
        }

        if (rc == 0)
                ata_port_schedule_eh(ap);

        spin_unlock_irqrestore(ap->lock, flags);

        return rc;
}

/**
 *      ata_scsi_dev_rescan - initiate scsi_rescan_device()
 *      @data: Pointer to ATA port to perform scsi_rescan_device()
 *
 *      After ATA pass thru (SAT) commands are executed successfully,
 *      libata need to propagate the changes to SCSI layer.  This
 *      function must be executed from ata_aux_wq such that sdev
 *      attach/detach don't race with rescan.
 *
 *      LOCKING:
 *      Kernel thread context (may sleep).
 */
void ata_scsi_dev_rescan(void *data)
{
        struct ata_port *ap = data;
        struct ata_device *dev;
        unsigned int i;

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

                if (ata_dev_enabled(dev) && dev->sdev)
                        scsi_rescan_device(&(dev->sdev->sdev_gendev));
        }
}