libata: minor whitespace, comment, debug message updates

[linux-2.6/suspend2-2.6.18.git] / 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.h"
#include <scsi/scsi_host.h>
#include <linux/libata.h>
#include <asm/uaccess.h>

#include "libata.h"

typedef unsigned int (*ata_xlat_func_t)(struct ata_queued_cmd *qc, u8 *scsicmd);
static struct ata_device *
ata_scsi_find_dev(struct ata_port *ap, struct scsi_device *scsidev);


/**
 *      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;
}

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

        ap = (struct ata_port *) &scsidev->host->hostdata[0];
        if (!ap)
                goto out;

        dev = ata_scsi_find_dev(ap, scsidev);
        if (!dev) {
                rc = -ENODEV;
                goto out;
        }

        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;

        default:
                rc = -ENOTTY;
                break;
        }

out:
        return rc;
}

/**
 *      ata_scsi_qc_new - acquire new ata_queued_cmd reference
 *      @ap: ATA port to which the new command is attached
 *      @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_port *ap,
                                       struct ata_device *dev,
                                       struct scsi_cmnd *cmd,
                                       void (*done)(struct scsi_cmnd *))
{
        struct ata_queued_cmd *qc;

        qc = ata_qc_new_init(ap, 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_to_sense_error - convert ATA error to SCSI error
 *      @qc: Command that we are erroring out
 *      @drv_stat: value contained in ATA status register
 *
 *      Converts an ATA error into a SCSI error. While we are at it
 *      we decode and dump the ATA error for the user so that they
 *      have some idea what really happened at the non make-believe
 *      layer.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

void ata_to_sense_error(struct ata_queued_cmd *qc, u8 drv_stat)
{
        struct scsi_cmnd *cmd = qc->scsicmd;
        u8 err = 0;
        unsigned char *sb = cmd->sense_buffer;
        /* Based on the 3ware driver translation table */
        static 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 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
        };
        int i = 0;

        cmd->result = SAM_STAT_CHECK_CONDITION;

        /*
         *      Is this an error we can process/parse
         */

        if(drv_stat & ATA_ERR)
                /* Read the err bits */
                err = ata_chk_err(qc->ap);

        /* Display the ATA level error info */

        printk(KERN_WARNING "ata%u: status=0x%02x { ", qc->ap->id, drv_stat);
        if(drv_stat & 0x80)
        {
                printk("Busy ");
                err = 0;        /* Data is not valid in this case */
        }
        else {
                if(drv_stat & 0x40)     printk("DriveReady ");
                if(drv_stat & 0x20)     printk("DeviceFault ");
                if(drv_stat & 0x10)     printk("SeekComplete ");
                if(drv_stat & 0x08)     printk("DataRequest ");
                if(drv_stat & 0x04)     printk("CorrectedError ");
                if(drv_stat & 0x02)     printk("Index ");
                if(drv_stat & 0x01)     printk("Error ");
        }
        printk("}\n");

        if(err)
        {
                printk(KERN_WARNING "ata%u: error=0x%02x { ", qc->ap->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");

                /* Should we dump sector info here too ?? */
        }


        /* Look for err */
        while(sense_table[i][0] != 0xFF)
        {
                /* Look for best matches first */
                if((sense_table[i][0] & err) == sense_table[i][0])
                {
                        sb[0] = 0x70;
                        sb[2] = sense_table[i][1];
                        sb[7] = 0x0a;
                        sb[12] = sense_table[i][2];
                        sb[13] = sense_table[i][3];
                        return;
                }
                i++;
        }
        /* No immediate match */
        if(err)
                printk(KERN_DEBUG "ata%u: no sense translation for 0x%02x\n", qc->ap->id, err);

        i = 0;
        /* Fall back to interpreting status bits */
        while(stat_table[i][0] != 0xFF)
        {
                if(stat_table[i][0] & drv_stat)
                {
                        sb[0] = 0x70;
                        sb[2] = stat_table[i][1];
                        sb[7] = 0x0a;
                        sb[12] = stat_table[i][2];
                        sb[13] = stat_table[i][3];
                        return;
                }
                i++;
        }
        /* No error ?? */
        printk(KERN_ERR "ata%u: called with no error (%02X)!\n", qc->ap->id, drv_stat);
        /* additional-sense-code[-qualifier] */

        sb[0] = 0x70;
        sb[2] = MEDIUM_ERROR;
        sb[7] = 0x0A;
        if (cmd->sc_data_direction == DMA_FROM_DEVICE) {
                sb[12] = 0x11; /* "unrecovered read error" */
                sb[13] = 0x04;
        } else {
                sb[12] = 0x0C; /* "write error -             */
                sb[13] = 0x02; /*  auto-reallocation failed" */
        }
}

/**
 *      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)
{
        sdev->use_10_for_rw = 1;
        sdev->use_10_for_ms = 1;

        blk_queue_max_phys_segments(sdev->request_queue, LIBATA_MAX_PRD);

        if (sdev->id < ATA_MAX_DEVICES) {
                struct ata_port *ap;
                struct ata_device *dev;

                ap = (struct ata_port *) &sdev->host->hostdata[0];
                dev = &ap->device[sdev->id];

                /* TODO: 1024 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.
                 */
                if ((dev->flags & ATA_DFLAG_LBA48) &&
                    ((dev->flags & ATA_DFLAG_LOCK_SECTORS) == 0)) {
                        /*
                         * do not overwrite sdev->host->max_sectors, since
                         * other drives on this host may not support LBA48
                         */
                        blk_queue_max_sectors(sdev->request_queue, 2048);
                }
        }

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

/**
 *      ata_scsi_error - SCSI layer error handler callback
 *      @host: SCSI host on which error occurred
 *
 *      Handles SCSI-layer-thrown error events.
 *
 *      LOCKING:
 *      Inherited from SCSI layer (none, can sleep)
 *
 *      RETURNS:
 *      Zero.
 */

int ata_scsi_error(struct Scsi_Host *host)
{
        struct ata_port *ap;

        DPRINTK("ENTER\n");

        ap = (struct ata_port *) &host->hostdata[0];
        ap->ops->eng_timeout(ap);

        /* TODO: this is per-command; when queueing is supported
         * this code will either change or move to a more
         * appropriate place
         */
        host->host_failed--;
        INIT_LIST_HEAD(&host->eh_cmd_q);

        DPRINTK("EXIT\n");
        return 0;
}

/**
 *      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,
                                             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)
                return 1;       /* LOEJ bit set not supported */
        if (((scsicmd[4] >> 4) & 0xf) != 0)
                return 1;       /* power conditions not supported */
        if (scsicmd[4] & 0x1) {
                tf->nsect = 1;  /* 1 sector, lba=0 */
                tf->lbah = 0x0;
                tf->lbam = 0x0;
                tf->lbal = 0x0;
                tf->device |= ATA_LBA;
                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;
}


/**
 *      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, u8 *scsicmd)
{
        struct ata_taskfile *tf = &qc->tf;

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

        if ((tf->flags & ATA_TFLAG_LBA48) &&
            (ata_id_has_flush_ext(qc->dev->id)))
                tf->command = ATA_CMD_FLUSH_EXT;
        else
                tf->command = ATA_CMD_FLUSH;

        return 0;
}

/**
 *      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, u8 *scsicmd)
{
        struct ata_taskfile *tf = &qc->tf;
        struct ata_device *dev = qc->dev;
        unsigned int lba   = tf->flags & ATA_TFLAG_LBA;
        unsigned int lba48 = tf->flags & ATA_TFLAG_LBA48;
        u64 dev_sectors = qc->dev->n_sectors;
        u64 block = 0;
        u32 n_block = 0;

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

        if (scsicmd[0] == VERIFY) {
                block |= ((u64)scsicmd[2]) << 24;
                block |= ((u64)scsicmd[3]) << 16;
                block |= ((u64)scsicmd[4]) << 8;
                block |= ((u64)scsicmd[5]);

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

        else if (scsicmd[0] == VERIFY_16) {
                block |= ((u64)scsicmd[2]) << 56;
                block |= ((u64)scsicmd[3]) << 48;
                block |= ((u64)scsicmd[4]) << 40;
                block |= ((u64)scsicmd[5]) << 32;
                block |= ((u64)scsicmd[6]) << 24;
                block |= ((u64)scsicmd[7]) << 16;
                block |= ((u64)scsicmd[8]) << 8;
                block |= ((u64)scsicmd[9]);

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

        else
                return 1;

        if (!n_block)
                return 1;
        if (block >= dev_sectors)
                return 1;
        if ((block + n_block) > dev_sectors)
                return 1;
        if (lba48) {
                if (n_block > (64 * 1024))
                        return 1;
        } else {
                if (n_block > 256)
                        return 1;
        }

        if (lba) {
                if (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 {
                        tf->command = ATA_CMD_VERIFY;

                        tf->device |= (block >> 24) & 0xf;
                }

                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;

                /* 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)) 
                        return 1;
                
                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;
}

/**
 *      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, u8 *scsicmd)
{
        struct ata_taskfile *tf = &qc->tf;
        struct ata_device *dev = qc->dev;
        unsigned int lba   = tf->flags & ATA_TFLAG_LBA;
        unsigned int lba48 = tf->flags & ATA_TFLAG_LBA48;
        u64 block = 0;
        u32 n_block = 0;

        tf->flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
        tf->protocol = qc->dev->xfer_protocol;

        if (scsicmd[0] == READ_10 || scsicmd[0] == READ_6 ||
            scsicmd[0] == READ_16) {
                tf->command = qc->dev->read_cmd;
        } else {
                tf->command = qc->dev->write_cmd;
                tf->flags |= ATA_TFLAG_WRITE;
        }

        /* Calculate the SCSI LBA and transfer length. */
        if (scsicmd[0] == READ_10 || scsicmd[0] == WRITE_10) {
                block |= ((u64)scsicmd[2]) << 24;
                block |= ((u64)scsicmd[3]) << 16;
                block |= ((u64)scsicmd[4]) << 8;
                block |= ((u64)scsicmd[5]);

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

                VPRINTK("ten-byte command\n");
        } else if (scsicmd[0] == READ_6 || scsicmd[0] == WRITE_6) {
                block |= ((u64)scsicmd[2]) << 8;
                block |= ((u64)scsicmd[3]);

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

                /* for 6-byte r/w commands, transfer length 0
                 * means 256 blocks of data, not 0 block.
                 */
                if (!n_block)
                        n_block = 256;
        
                VPRINTK("six-byte command\n");
        } else if (scsicmd[0] == READ_16 || scsicmd[0] == WRITE_16) {
                block |= ((u64)scsicmd[2]) << 56;
                block |= ((u64)scsicmd[3]) << 48;
                block |= ((u64)scsicmd[4]) << 40;
                block |= ((u64)scsicmd[5]) << 32;
                block |= ((u64)scsicmd[6]) << 24;
                block |= ((u64)scsicmd[7]) << 16;
                block |= ((u64)scsicmd[8]) << 8;
                block |= ((u64)scsicmd[9]);

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

                VPRINTK("sixteen-byte command\n");
        } else {
                DPRINTK("no-byte command\n");
                return 1;
        }

        /* 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.
                 */
                return 1;

        if (lba) {
                if (lba48) {
                        /* The request -may- be too large for LBA48. */
                        if ((block >> 48) || (n_block > 65536))
                                return 1;

                        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 { 
                        /* LBA28 */

                        /* The request -may- be too large for LBA28. */
                        if ((block >> 28) || (n_block > 256))
                                return 1;

                        tf->device |= (block >> 24) & 0xf;
                }

                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 ((block >> 28) || (n_block > 256))
                        return 1;

                /* 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))
                        return 1;

                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;
}

static int ata_scsi_qc_complete(struct ata_queued_cmd *qc, u8 drv_stat)
{
        struct scsi_cmnd *cmd = qc->scsicmd;

        if (unlikely(drv_stat & (ATA_ERR | ATA_BUSY | ATA_DRQ)))
                ata_to_sense_error(qc, drv_stat);
        else
                cmd->result = SAM_STAT_GOOD;

        qc->scsidone(cmd);

        return 0;
}

/**
 *      ata_scsi_translate - Translate then issue SCSI command to ATA device
 *      @ap: ATA port to which the command is addressed
 *      @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.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

static void ata_scsi_translate(struct ata_port *ap, 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;

        VPRINTK("ENTER\n");

        qc = ata_scsi_qc_new(ap, dev, cmd, done);
        if (!qc)
                return;

        /* 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)) {
                        printk(KERN_WARNING "ata%u(%u): WARNING: zero len r/w req\n",
                               ap->id, dev->devno);
                        goto err_out;
                }

                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 err_out;

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

        VPRINTK("EXIT\n");
        return;

err_out:
        ata_qc_free(qc);
        ata_bad_cdb(cmd, done);
        DPRINTK("EXIT - badcmd\n");
}

/**
 *      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, or not.
 *
 *      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)
                ata_bad_cdb(cmd, args->done);
        else {
                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-EVPD 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_dev_id_string(args->id, &rbuf[16], ATA_ID_PROD_OFS, 16);
                ata_dev_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 EVPD 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 EVPD 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 EVPD pages */

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

        return 0;
}

/**
 *      ata_scsiop_inq_80 - Simulate INQUIRY EVPD 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_dev_id_string(args->id, (unsigned char *) &rbuf[4],
                                  ATA_ID_SERNO_OFS, ATA_SERNO_LEN);

        return 0;
}

static const char *inq_83_str = "Linux ATA-SCSI simulator";

/**
 *      ata_scsiop_inq_83 - Simulate INQUIRY EVPD 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.
 *
 *      Returns device identification.  Currently hardcoded to
 *      return "Linux ATA-SCSI simulator".
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

unsigned int ata_scsiop_inq_83(struct ata_scsi_args *args, u8 *rbuf,
                              unsigned int buflen)
{
        rbuf[1] = 0x83;                 /* this page code */
        rbuf[3] = 4 + strlen(inq_83_str);       /* page len */

        /* our one and only identification descriptor (vendor-specific) */
        if (buflen > (strlen(inq_83_str) + 4 + 4 - 1)) {
                rbuf[4 + 0] = 2;        /* code set: ASCII */
                rbuf[4 + 3] = strlen(inq_83_str);
                memcpy(rbuf + 4 + 4, inq_83_str, strlen(inq_83_str));
        }

        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[] = {
                0x8,                            /* page code */
                0x12,                           /* page length */
                0, 0, 0, 0, 0, 0, 0, 0, 0, 0,   /* 10 zeroes */
                0, 0, 0, 0, 0, 0, 0, 0          /* 8 zeroes */
        };

        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)
{
        const u8 page[] = {0xa, 0xa, 6, 0, 0, 0, 0, 0, 0xff, 0xff, 0, 30};

        /* byte 2: set the descriptor format sense data bit (bit 2)
         * since we need to support returning this format for SAT
         * commands and any SCSI commands against a 48b LBA device.
         */

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

/**
 *      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)
{
        const u8 page[] = {
                0x1,                      /* page code */
                0xa,                      /* page length */
                (1 << 7) | (1 << 6),      /* note auto r/w reallocation */
                0, 0, 0, 0, 0, 0, 0, 0, 0 /* 9 zeroes */
        };

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

/**
 *      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.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */

unsigned int ata_scsiop_mode_sense(struct ata_scsi_args *args, u8 *rbuf,
                                  unsigned int buflen)
{
        u8 *scsicmd = args->cmd->cmnd, *p, *last;
        unsigned int page_control, six_byte, output_len;

        VPRINTK("ENTER\n");

        six_byte = (scsicmd[0] == MODE_SENSE);

        /* we only support saved and current values (which we treat
         * in the same manner)
         */
        page_control = scsicmd[2] >> 6;
        if ((page_control != 0) && (page_control != 3))
                return 1;

        if (six_byte)
                output_len = 4;
        else
                output_len = 8;

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

        switch(scsicmd[2] & 0x3f) {
        case 0x01:              /* r/w error recovery */
                output_len += ata_msense_rw_recovery(&p, last);
                break;

        case 0x08:              /* caching */
                output_len += ata_msense_caching(args->id, &p, last);
                break;

        case 0x0a: {            /* control mode */
                output_len += ata_msense_ctl_mode(&p, last);
                break;
                }

        case 0x3f:              /* all pages */
                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 */
                return 1;
        }

        if (six_byte) {
                output_len--;
                rbuf[0] = output_len;
        } else {
                output_len -= 2;
                rbuf[0] = output_len >> 8;
                rbuf[1] = output_len;
        }

        return 0;
}

/**
 *      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_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");
        cmd->result = SAM_STAT_CHECK_CONDITION;

        cmd->sense_buffer[0] = 0x70;
        cmd->sense_buffer[2] = ILLEGAL_REQUEST;
        cmd->sense_buffer[7] = 14 - 8;  /* addnl. sense len. FIXME: correct? */
        cmd->sense_buffer[12] = asc;
        cmd->sense_buffer[13] = ascq;

        done(cmd);
}

static int atapi_qc_complete(struct ata_queued_cmd *qc, u8 drv_stat)
{
        struct scsi_cmnd *cmd = qc->scsicmd;

        if (unlikely(drv_stat & (ATA_ERR | ATA_BUSY | ATA_DRQ))) {
                DPRINTK("request check condition\n");

                cmd->result = SAM_STAT_CHECK_CONDITION;

                qc->scsidone(cmd);

                return 1;
        } else {
                u8 *scsicmd = cmd->cmnd;

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

                        buflen = ata_scsi_rbuf_get(cmd, &buf);
                        buf[2] = 0x5;
                        buf[3] = (buf[3] & 0xf0) | 2;
                        ata_scsi_rbuf_put(cmd, buf);
                }
                cmd->result = SAM_STAT_GOOD;
        }

        qc->scsidone(cmd);

        return 0;
}
/**
 *      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, 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, qc->ap->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;

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

        qc->nbytes = cmd->bufflen;

        return 0;
}

/**
 *      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, struct scsi_device *scsidev)
{
        struct ata_device *dev;

        /* skip commands not addressed to targets we simulate */
        if (likely(scsidev->id < ATA_MAX_DEVICES))
                dev = &ap->device[scsidev->id];
        else
                return NULL;

        if (unlikely((scsidev->channel != 0) ||
                     (scsidev->lun != 0)))
                return NULL;

        if (unlikely(!ata_dev_present(dev)))
                return NULL;

        if (!atapi_enabled) {
                if (unlikely(dev->class == ATA_DEV_ATAPI))
                        return NULL;
        }

        return dev;
}

/**
 *      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 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
}

/**
 *      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:
 *      Zero.
 */

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;

        ap = (struct ata_port *) &scsidev->host->hostdata[0];

        ata_scsi_dump_cdb(ap, cmd);

        dev = ata_scsi_find_dev(ap, scsidev);
        if (unlikely(!dev)) {
                cmd->result = (DID_BAD_TARGET << 16);
                done(cmd);
                goto out_unlock;
        }

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

                if (xlat_func)
                        ata_scsi_translate(ap, dev, cmd, done, xlat_func);
                else
                        ata_scsi_simulate(dev->id, cmd, done);
        } else
                ata_scsi_translate(ap, dev, cmd, done, atapi_xlat);

out_unlock:
        return 0;
}

/**
 *      ata_scsi_simulate - simulate SCSI command on ATA device
 *      @id: current IDENTIFY data for 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(u16 *id,
                      struct scsi_cmnd *cmd,
                      void (*done)(struct scsi_cmnd *))
{
        struct ata_scsi_args args;
        u8 *scsicmd = cmd->cmnd;

        args.id = 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_bad_cdb(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_bad_cdb(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_bad_cdb(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_bad_cdb(cmd, done);
                        break;

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

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

                /* all other commands */
                default:
                        ata_bad_scsiop(cmd, done);
                        break;
        }
}