- pre5:

[davej-history.git] / drivers / scsi / sd.c

/*
 *      sd.c Copyright (C) 1992 Drew Eckhardt
 *           Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
 *
 *      Linux scsi disk driver
 *              Initial versions: Drew Eckhardt
 *              Subsequent revisions: Eric Youngdale
 *
 *      <drew@colorado.edu>
 *
 *       Modified by Eric Youngdale ericy@andante.org to
 *       add scatter-gather, multiple outstanding request, and other
 *       enhancements.
 *
 *       Modified by Eric Youngdale eric@andante.org to support loadable
 *       low-level scsi drivers.
 *
 *       Modified by Jirka Hanika geo@ff.cuni.cz to support more
 *       scsi disks using eight major numbers.
 *
 *       Modified by Richard Gooch rgooch@atnf.csiro.au to support devfs.
 */

#include <linux/config.h>
#include <linux/module.h>

#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/hdreg.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/init.h>

#include <linux/smp.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>

#define MAJOR_NR SCSI_DISK0_MAJOR
#include <linux/blk.h>
#include <linux/blkpg.h>
#include "scsi.h"
#include "hosts.h"
#include "sd.h"
#include <scsi/scsi_ioctl.h>
#include "constants.h"
#include <scsi/scsicam.h>       /* must follow "hosts.h" */

#include <linux/genhd.h>

/*
 *  static const char RCSid[] = "$Header:";
 */

#define SD_MAJOR(i) (!(i) ? SCSI_DISK0_MAJOR : SCSI_DISK1_MAJOR-1+(i))

#define SCSI_DISKS_PER_MAJOR    16
#define SD_MAJOR_NUMBER(i)      SD_MAJOR((i) >> 8)
#define SD_MINOR_NUMBER(i)      ((i) & 255)
#define MKDEV_SD_PARTITION(i)   MKDEV(SD_MAJOR_NUMBER(i), (i) & 255)
#define MKDEV_SD(index)         MKDEV_SD_PARTITION((index) << 4)
#define N_USED_SCSI_DISKS  (sd_template.dev_max + SCSI_DISKS_PER_MAJOR - 1)
#define N_USED_SD_MAJORS   (N_USED_SCSI_DISKS / SCSI_DISKS_PER_MAJOR)

#define MAX_RETRIES 5

/*
 *  Time out in seconds for disks and Magneto-opticals (which are slower).
 */

#define SD_TIMEOUT (30 * HZ)
#define SD_MOD_TIMEOUT (75 * HZ)

struct hd_struct *sd;

static Scsi_Disk *rscsi_disks = NULL;
static int *sd_sizes;
static int *sd_blocksizes;
static int *sd_hardsizes;       /* Hardware sector size */

static int check_scsidisk_media_change(kdev_t);
static int fop_revalidate_scsidisk(kdev_t);

static int sd_init_onedisk(int);


static int sd_init(void);
static void sd_finish(void);
static int sd_attach(Scsi_Device *);
static int sd_detect(Scsi_Device *);
static void sd_detach(Scsi_Device *);
static void rw_intr(Scsi_Cmnd * SCpnt);

static int sd_init_command(Scsi_Cmnd *);

#if defined(CONFIG_PPC)
/*
 * Moved from arch/ppc/pmac_setup.c.  This is where it really belongs.
 */
kdev_t __init
sd_find_target(void *host, int tgt)
{
    Scsi_Disk *dp;
    int i;
    for (dp = rscsi_disks, i = 0; i < sd_template.dev_max; ++i, ++dp)
        if (dp->device != NULL && dp->device->host == host
            && dp->device->id == tgt)
            return MKDEV_SD(i);
    return 0;
}
#endif

static int sd_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg)
{
        kdev_t dev = inode->i_rdev;
        struct Scsi_Host * host;
        Scsi_Device * SDev;
        int diskinfo[4];
    
        SDev = rscsi_disks[DEVICE_NR(dev)].device;
        /*
         * If we are in the middle of error recovery, don't let anyone
         * else try and use this device.  Also, if error recovery fails, it
         * may try and take the device offline, in which case all further
         * access to the device is prohibited.
         */

        if( !scsi_block_when_processing_errors(SDev) )
        {
                return -ENODEV;
        }

        switch (cmd) 
        {
                case HDIO_GETGEO:   /* Return BIOS disk parameters */
                {
                        struct hd_geometry *loc = (struct hd_geometry *) arg;
                        if(!loc)
                                return -EINVAL;

                        host = rscsi_disks[DEVICE_NR(dev)].device->host;
        
                        /* default to most commonly used values */
        
                        diskinfo[0] = 0x40;
                        diskinfo[1] = 0x20;
                        diskinfo[2] = rscsi_disks[DEVICE_NR(dev)].capacity >> 11;
        
                        /* override with calculated, extended default, or driver values */
        
                        if(host->hostt->bios_param != NULL)
                                host->hostt->bios_param(&rscsi_disks[DEVICE_NR(dev)],
                                            dev,
                                            &diskinfo[0]);
                        else scsicam_bios_param(&rscsi_disks[DEVICE_NR(dev)],
                                        dev, &diskinfo[0]);

                        if (put_user(diskinfo[0], &loc->heads) ||
                                put_user(diskinfo[1], &loc->sectors) ||
                                put_user(diskinfo[2], &loc->cylinders) ||
                                put_user(sd[SD_PARTITION(inode->i_rdev)].start_sect, &loc->start))
                                return -EFAULT;
                        return 0;
                }
                case HDIO_GETGEO_BIG:
                {
                        struct hd_big_geometry *loc = (struct hd_big_geometry *) arg;

                        if(!loc)
                                return -EINVAL;

                        host = rscsi_disks[DEVICE_NR(dev)].device->host;

                        /* default to most commonly used values */

                        diskinfo[0] = 0x40;
                        diskinfo[1] = 0x20;
                        diskinfo[2] = rscsi_disks[DEVICE_NR(dev)].capacity >> 11;

                        /* override with calculated, extended default, or driver values */

                        if(host->hostt->bios_param != NULL)
                                host->hostt->bios_param(&rscsi_disks[DEVICE_NR(dev)],
                                            dev,
                                            &diskinfo[0]);
                        else scsicam_bios_param(&rscsi_disks[DEVICE_NR(dev)],
                                        dev, &diskinfo[0]);

                        if (put_user(diskinfo[0], &loc->heads) ||
                                put_user(diskinfo[1], &loc->sectors) ||
                                put_user(diskinfo[2], (unsigned int *) &loc->cylinders) ||
                                put_user(sd[SD_PARTITION(inode->i_rdev)].start_sect, &loc->start))
                                return -EFAULT;
                        return 0;
                }
                case BLKGETSIZE:   /* Return device size */
                        if (!arg)
                                return -EINVAL;
                        return put_user(sd[SD_PARTITION(inode->i_rdev)].nr_sects, (long *) arg);

                case BLKROSET:
                case BLKROGET:
                case BLKRASET:
                case BLKRAGET:
                case BLKFLSBUF:
                case BLKSSZGET:
                case BLKPG:
                case BLKELVGET:
                case BLKELVSET:
                        return blk_ioctl(inode->i_rdev, cmd, arg);

                case BLKRRPART: /* Re-read partition tables */
                        if (!capable(CAP_SYS_ADMIN))
                                return -EACCES;
                        return revalidate_scsidisk(dev, 1);

                default:
                        return scsi_ioctl(rscsi_disks[DEVICE_NR(dev)].device , cmd, (void *) arg);
        }
}

static void sd_devname(unsigned int disknum, char *buffer)
{
        if (disknum < 26)
                sprintf(buffer, "sd%c", 'a' + disknum);
        else {
                unsigned int min1;
                unsigned int min2;
                /*
                 * For larger numbers of disks, we need to go to a new
                 * naming scheme.
                 */
                min1 = disknum / 26;
                min2 = disknum % 26;
                sprintf(buffer, "sd%c%c", 'a' + min1 - 1, 'a' + min2);
        }
}

struct Scsi_Device_Template sd_template = {
        name:"disk",
        tag:"sd",
        scsi_type:TYPE_DISK,
        major:SCSI_DISK0_MAJOR,
        /*
         * Secondary range of majors that this driver handles.
         */
        min_major:SCSI_DISK1_MAJOR,
        max_major:SCSI_DISK7_MAJOR,
        blk:1,
        detect:sd_detect,
        init:sd_init,
        finish:sd_finish,
        attach:sd_attach,
        detach:sd_detach,
        init_command:sd_init_command,
};

static request_queue_t *sd_find_queue(kdev_t dev)
{
        Scsi_Disk *dpnt;
        int target;
        target = DEVICE_NR(dev);

        dpnt = &rscsi_disks[target];
        if (!dpnt)
                return NULL;    /* No such device */
        return &dpnt->device->request_queue;
}

static int sd_init_command(Scsi_Cmnd * SCpnt)
{
        int dev, devm, block, this_count;
        Scsi_Disk *dpnt;
#if CONFIG_SCSI_LOGGING
        char nbuff[6];
#endif

        devm = SD_PARTITION(SCpnt->request.rq_dev);
        dev = DEVICE_NR(SCpnt->request.rq_dev);

        block = SCpnt->request.sector;
        this_count = SCpnt->request_bufflen >> 9;

        SCSI_LOG_HLQUEUE(1, printk("Doing sd request, dev = %d, block = %d\n", devm, block));

        dpnt = &rscsi_disks[dev];
        if (devm >= (sd_template.dev_max << 4) ||
            !dpnt ||
            !dpnt->device->online ||
            block + SCpnt->request.nr_sectors > sd[devm].nr_sects) {
                SCSI_LOG_HLQUEUE(2, printk("Finishing %ld sectors\n", SCpnt->request.nr_sectors));
                SCSI_LOG_HLQUEUE(2, printk("Retry with 0x%p\n", SCpnt));
                return 0;
        }
        block += sd[devm].start_sect;
        if (dpnt->device->changed) {
                /*
                 * quietly refuse to do anything to a changed disc until the changed
                 * bit has been reset
                 */
                /* printk("SCSI disk has been changed. Prohibiting further I/O.\n"); */
                return 0;
        }
        SCSI_LOG_HLQUEUE(2, sd_devname(devm, nbuff));
        SCSI_LOG_HLQUEUE(2, printk("%s : real dev = /dev/%d, block = %d\n",
                                   nbuff, dev, block));

        /*
         * If we have a 1K hardware sectorsize, prevent access to single
         * 512 byte sectors.  In theory we could handle this - in fact
         * the scsi cdrom driver must be able to handle this because
         * we typically use 1K blocksizes, and cdroms typically have
         * 2K hardware sectorsizes.  Of course, things are simpler
         * with the cdrom, since it is read-only.  For performance
         * reasons, the filesystems should be able to handle this
         * and not force the scsi disk driver to use bounce buffers
         * for this.
         */
        if (dpnt->device->sector_size == 1024) {
                if ((block & 1) || (SCpnt->request.nr_sectors & 1)) {
                        printk("sd.c:Bad block number requested");
                        return 0;
                } else {
                        block = block >> 1;
                        this_count = this_count >> 1;
                }
        }
        if (dpnt->device->sector_size == 2048) {
                if ((block & 3) || (SCpnt->request.nr_sectors & 3)) {
                        printk("sd.c:Bad block number requested");
                        return 0;
                } else {
                        block = block >> 2;
                        this_count = this_count >> 2;
                }
        }
        if (dpnt->device->sector_size == 4096) {
                if ((block & 7) || (SCpnt->request.nr_sectors & 7)) {
                        printk("sd.c:Bad block number requested");
                        return 0;
                } else {
                        block = block >> 3;
                        this_count = this_count >> 3;
                }
        }
        switch (SCpnt->request.cmd) {
        case WRITE:
                if (!dpnt->device->writeable) {
                        return 0;
                }
                SCpnt->cmnd[0] = WRITE_6;
                SCpnt->sc_data_direction = SCSI_DATA_WRITE;
                break;
        case READ:
                SCpnt->cmnd[0] = READ_6;
                SCpnt->sc_data_direction = SCSI_DATA_READ;
                break;
        default:
                panic("Unknown sd command %d\n", SCpnt->request.cmd);
        }

        SCSI_LOG_HLQUEUE(2, printk("%s : %s %d/%ld 512 byte blocks.\n",
                                   nbuff,
                   (SCpnt->request.cmd == WRITE) ? "writing" : "reading",
                                 this_count, SCpnt->request.nr_sectors));

        SCpnt->cmnd[1] = (SCpnt->lun << 5) & 0xe0;

        if (((this_count > 0xff) || (block > 0x1fffff)) || SCpnt->device->ten) {
                if (this_count > 0xffff)
                        this_count = 0xffff;

                SCpnt->cmnd[0] += READ_10 - READ_6;
                SCpnt->cmnd[2] = (unsigned char) (block >> 24) & 0xff;
                SCpnt->cmnd[3] = (unsigned char) (block >> 16) & 0xff;
                SCpnt->cmnd[4] = (unsigned char) (block >> 8) & 0xff;
                SCpnt->cmnd[5] = (unsigned char) block & 0xff;
                SCpnt->cmnd[6] = SCpnt->cmnd[9] = 0;
                SCpnt->cmnd[7] = (unsigned char) (this_count >> 8) & 0xff;
                SCpnt->cmnd[8] = (unsigned char) this_count & 0xff;
        } else {
                if (this_count > 0xff)
                        this_count = 0xff;

                SCpnt->cmnd[1] |= (unsigned char) ((block >> 16) & 0x1f);
                SCpnt->cmnd[2] = (unsigned char) ((block >> 8) & 0xff);
                SCpnt->cmnd[3] = (unsigned char) block & 0xff;
                SCpnt->cmnd[4] = (unsigned char) this_count;
                SCpnt->cmnd[5] = 0;
        }

        /*
         * We shouldn't disconnect in the middle of a sector, so with a dumb
         * host adapter, it's safe to assume that we can at least transfer
         * this many bytes between each connect / disconnect.
         */
        SCpnt->transfersize = dpnt->device->sector_size;
        SCpnt->underflow = this_count << 9;

        SCpnt->allowed = MAX_RETRIES;
        SCpnt->timeout_per_command = (SCpnt->device->type == TYPE_DISK ?
                                      SD_TIMEOUT : SD_MOD_TIMEOUT);

        /*
         * This is the completion routine we use.  This is matched in terms
         * of capability to this function.
         */
        SCpnt->done = rw_intr;

        /*
         * This indicates that the command is ready from our end to be
         * queued.
         */
        return 1;
}

static int sd_open(struct inode *inode, struct file *filp)
{
        int target;
        Scsi_Device * SDev;
        target = DEVICE_NR(inode->i_rdev);

        SCSI_LOG_HLQUEUE(1, printk("target=%d, max=%d\n", target, sd_template.dev_max));

        if (target >= sd_template.dev_max || !rscsi_disks[target].device)
                return -ENXIO;  /* No such device */

        /*
         * If the device is in error recovery, wait until it is done.
         * If the device is offline, then disallow any access to it.
         */
        if (!scsi_block_when_processing_errors(rscsi_disks[target].device)) {
                return -ENXIO;
        }
        /*
         * Make sure that only one process can do a check_change_disk at one time.
         * This is also used to lock out further access when the partition table
         * is being re-read.
         */

        while (rscsi_disks[target].device->busy)
                barrier();
        if (rscsi_disks[target].device->removable) {
                check_disk_change(inode->i_rdev);

                /*
                 * If the drive is empty, just let the open fail.
                 */
                if (!rscsi_disks[target].ready)
                        return -ENXIO;

                /*
                 * Similarly, if the device has the write protect tab set,
                 * have the open fail if the user expects to be able to write
                 * to the thing.
                 */
                if ((rscsi_disks[target].write_prot) && (filp->f_mode & 2))
                        return -EROFS;
        }
        SDev = rscsi_disks[target].device;
        /*
         * It is possible that the disk changing stuff resulted in the device
         * being taken offline.  If this is the case, report this to the user,
         * and don't pretend that
         * the open actually succeeded.
         */
        if (!SDev->online) {
                return -ENXIO;
        }
        /*
         * See if we are requesting a non-existent partition.  Do this
         * after checking for disk change.
         */
        if (sd_sizes[SD_PARTITION(inode->i_rdev)] == 0)
                return -ENXIO;

        if (SDev->removable)
                if (!SDev->access_count)
                        if (scsi_block_when_processing_errors(SDev))
                                scsi_ioctl(SDev, SCSI_IOCTL_DOORLOCK, NULL);

        SDev->access_count++;
        if (SDev->host->hostt->module)
                __MOD_INC_USE_COUNT(SDev->host->hostt->module);
        if (sd_template.module)
                __MOD_INC_USE_COUNT(sd_template.module);
        return 0;
}

static int sd_release(struct inode *inode, struct file *file)
{
        int target;
        Scsi_Device * SDev;

        target = DEVICE_NR(inode->i_rdev);
        SDev = rscsi_disks[target].device;

        SDev->access_count--;

        if (SDev->removable) {
                if (!SDev->access_count)
                        if (scsi_block_when_processing_errors(SDev))
                                scsi_ioctl(SDev, SCSI_IOCTL_DOORUNLOCK, NULL);
        }
        if (SDev->host->hostt->module)
                __MOD_DEC_USE_COUNT(SDev->host->hostt->module);
        if (sd_template.module)
                __MOD_DEC_USE_COUNT(sd_template.module);
        return 0;
}

static struct block_device_operations sd_fops =
{
        open:                   sd_open,
        release:                sd_release,
        ioctl:                  sd_ioctl,
        check_media_change:     check_scsidisk_media_change,
        revalidate:             fop_revalidate_scsidisk
};

/*
 *    If we need more than one SCSI disk major (i.e. more than
 *      16 SCSI disks), we'll have to kmalloc() more gendisks later.
 */

static struct gendisk sd_gendisk =
{
        SCSI_DISK0_MAJOR,       /* Major number */
        "sd",                   /* Major name */
        4,                      /* Bits to shift to get real from partition */
        1 << 4,                 /* Number of partitions per real */
        NULL,                   /* hd struct */
        NULL,                   /* block sizes */
        0,                      /* number */
        NULL,                   /* internal */
        NULL,                   /* next */
        &sd_fops,               /* file operations */
};

static struct gendisk *sd_gendisks = &sd_gendisk;

#define SD_GENDISK(i)    sd_gendisks[(i) / SCSI_DISKS_PER_MAJOR]
#define LAST_SD_GENDISK  sd_gendisks[N_USED_SD_MAJORS - 1]

/*
 * rw_intr is the interrupt routine for the device driver.
 * It will be notified on the end of a SCSI read / write, and
 * will take one of several actions based on success or failure.
 */

static void rw_intr(Scsi_Cmnd * SCpnt)
{
        int result = SCpnt->result;
#if CONFIG_SCSI_LOGGING
        char nbuff[6];
#endif
        int this_count = SCpnt->bufflen >> 9;
        int good_sectors = (result == 0 ? this_count : 0);
        int block_sectors = 1;

        SCSI_LOG_HLCOMPLETE(1, sd_devname(DEVICE_NR(SCpnt->request.rq_dev), nbuff));

        SCSI_LOG_HLCOMPLETE(1, printk("%s : rw_intr(%d, %x [%x %x])\n", nbuff,
                                      SCpnt->host->host_no,
                                      result,
                                      SCpnt->sense_buffer[0],
                                      SCpnt->sense_buffer[2]));

        /*
           Handle MEDIUM ERRORs that indicate partial success.  Since this is a
           relatively rare error condition, no care is taken to avoid
           unnecessary additional work such as memcpy's that could be avoided.
         */

        /* An error occurred */
        if (driver_byte(result) != 0) {
                /* Sense data is valid */
                if (SCpnt->sense_buffer[0] == 0xF0 && SCpnt->sense_buffer[2] == MEDIUM_ERROR) {
                        long error_sector = (SCpnt->sense_buffer[3] << 24) |
                        (SCpnt->sense_buffer[4] << 16) |
                        (SCpnt->sense_buffer[5] << 8) |
                        SCpnt->sense_buffer[6];
                        if (SCpnt->request.bh != NULL)
                                block_sectors = SCpnt->request.bh->b_size >> 9;
                        switch (SCpnt->device->sector_size) {
                        case 1024:
                                error_sector <<= 1;
                                if (block_sectors < 2)
                                        block_sectors = 2;
                                break;
                        case 2048:
                                error_sector <<= 2;
                                if (block_sectors < 4)
                                        block_sectors = 4;
                                break;
                        case 4096:
                                error_sector <<=3;
                                if (block_sectors < 8)
                                        block_sectors = 8;
                                break;
                        case 256:
                                error_sector >>= 1;
                                break;
                        default:
                                break;
                        }
                        error_sector -= sd[SD_PARTITION(SCpnt->request.rq_dev)].start_sect;
                        error_sector &= ~(block_sectors - 1);
                        good_sectors = error_sector - SCpnt->request.sector;
                        if (good_sectors < 0 || good_sectors >= this_count)
                                good_sectors = 0;
                }
                if (SCpnt->sense_buffer[2] == ILLEGAL_REQUEST) {
                        if (SCpnt->device->ten == 1) {
                                if (SCpnt->cmnd[0] == READ_10 ||
                                    SCpnt->cmnd[0] == WRITE_10)
                                        SCpnt->device->ten = 0;
                        }
                }
        }
        /*
         * This calls the generic completion function, now that we know
         * how many actual sectors finished, and how many sectors we need
         * to say have failed.
         */
        scsi_io_completion(SCpnt, good_sectors, block_sectors);
}
/*
 * requeue_sd_request() is the request handler function for the sd driver.
 * Its function in life is to take block device requests, and translate
 * them to SCSI commands.
 */


static int check_scsidisk_media_change(kdev_t full_dev)
{
        int retval;
        int target;
        int flag = 0;
        Scsi_Device * SDev;

        target = DEVICE_NR(full_dev);
        SDev = rscsi_disks[target].device;

        if (target >= sd_template.dev_max || !SDev) {
                printk("SCSI disk request error: invalid device.\n");
                return 0;
        }
        if (!SDev->removable)
                return 0;

        /*
         * If the device is offline, don't send any commands - just pretend as
         * if the command failed.  If the device ever comes back online, we
         * can deal with it then.  It is only because of unrecoverable errors
         * that we would ever take a device offline in the first place.
         */
        if (SDev->online == FALSE) {
                rscsi_disks[target].ready = 0;
                SDev->changed = 1;
                return 1;       /* This will force a flush, if called from
                                 * check_disk_change */
        }

        /* Using Start/Stop enables differentiation between drive with
         * no cartridge loaded - NOT READY, drive with changed cartridge -
         * UNIT ATTENTION, or with same cartridge - GOOD STATUS.
         * This also handles drives that auto spin down. eg iomega jaz 1GB
         * as this will spin up the drive.
         */
        retval = -ENODEV;
        if (scsi_block_when_processing_errors(SDev))
                retval = scsi_ioctl(SDev, SCSI_IOCTL_START_UNIT, NULL);

        if (retval) {           /* Unable to test, unit probably not ready.
                                 * This usually means there is no disc in the
                                 * drive.  Mark as changed, and we will figure
                                 * it out later once the drive is available
                                 * again.  */

                rscsi_disks[target].ready = 0;
                SDev->changed = 1;
                return 1;       /* This will force a flush, if called from
                                 * check_disk_change */
        }
        /*
         * for removable scsi disk ( FLOPTICAL ) we have to recognise the
         * presence of disk in the drive. This is kept in the Scsi_Disk
         * struct and tested at open !  Daniel Roche ( dan@lectra.fr )
         */

        rscsi_disks[target].ready = 1;  /* FLOPTICAL */

        retval = SDev->changed;
        if (!flag)
                SDev->changed = 0;
        return retval;
}

static int sd_init_onedisk(int i)
{
        unsigned char cmd[10];
        char nbuff[6];
        unsigned char *buffer;
        unsigned long spintime_value = 0;
        int the_result, retries, spintime;
        int sector_size;
        Scsi_Request *SRpnt;

        /*
         * Get the name of the disk, in case we need to log it somewhere.
         */
        sd_devname(i, nbuff);

        /*
         * If the device is offline, don't try and read capacity or any of the other
         * nicities.
         */
        if (rscsi_disks[i].device->online == FALSE) {
                return i;
        }
        /* We need to retry the READ_CAPACITY because a UNIT_ATTENTION is
         * considered a fatal error, and many devices report such an error
         * just after a scsi bus reset.
         */

        SRpnt = scsi_allocate_request(rscsi_disks[i].device);

        buffer = (unsigned char *) scsi_malloc(512);

        spintime = 0;

        /* Spin up drives, as required.  Only do this at boot time */
        /* Spinup needs to be done for module loads too. */
        do {
                retries = 0;

                while (retries < 3) {
                        cmd[0] = TEST_UNIT_READY;
                        cmd[1] = (rscsi_disks[i].device->lun << 5) & 0xe0;
                        memset((void *) &cmd[2], 0, 8);
                        SRpnt->sr_cmd_len = 0;
                        SRpnt->sr_sense_buffer[0] = 0;
                        SRpnt->sr_sense_buffer[2] = 0;
                        SRpnt->sr_data_direction = SCSI_DATA_READ;

                        scsi_wait_req (SRpnt, (void *) cmd, (void *) buffer,
                                0/*512*/, SD_TIMEOUT, MAX_RETRIES);

                        the_result = SRpnt->sr_result;
                        retries++;
                        if (the_result == 0
                            || SRpnt->sr_sense_buffer[2] != UNIT_ATTENTION)
                                break;
                }

                /*
                 * If the drive has indicated to us that it doesn't have
                 * any media in it, don't bother with any of the rest of
                 * this crap.
                 */
                if( the_result != 0
                    && ((driver_byte(the_result) & DRIVER_SENSE) != 0)
                    && SRpnt->sr_sense_buffer[2] == UNIT_ATTENTION
                    && SRpnt->sr_sense_buffer[12] == 0x3A ) {
                        rscsi_disks[i].capacity = 0x1fffff;
                        sector_size = 512;
                        rscsi_disks[i].device->changed = 1;
                        rscsi_disks[i].ready = 0;
                        break;
                }

                /* Look for non-removable devices that return NOT_READY.
                 * Issue command to spin up drive for these cases. */
                if (the_result && !rscsi_disks[i].device->removable &&
                    SRpnt->sr_sense_buffer[2] == NOT_READY) {
                        unsigned long time1;
                        if (!spintime) {
                                printk("%s: Spinning up disk...", nbuff);
                                cmd[0] = START_STOP;
                                cmd[1] = (rscsi_disks[i].device->lun << 5) & 0xe0;
                                cmd[1] |= 1;    /* Return immediately */
                                memset((void *) &cmd[2], 0, 8);
                                cmd[4] = 1;     /* Start spin cycle */
                                SRpnt->sr_cmd_len = 0;
                                SRpnt->sr_sense_buffer[0] = 0;
                                SRpnt->sr_sense_buffer[2] = 0;

                                SRpnt->sr_data_direction = SCSI_DATA_READ;
                                scsi_wait_req(SRpnt, (void *) cmd, (void *) buffer,
                                            0/*512*/, SD_TIMEOUT, MAX_RETRIES);
                        }
                        spintime = 1;
                        spintime_value = jiffies;
                        time1 = HZ;
                        /* Wait 1 second for next try */
                        do {
                                current->state = TASK_UNINTERRUPTIBLE;
                                time1 = schedule_timeout(time1);
                        } while(time1);
                        printk(".");
                }
        } while (the_result && spintime && time_after(spintime_value + 100 * HZ, jiffies));
        if (spintime) {
                if (the_result)
                        printk("not responding...\n");
                else
                        printk("ready\n");
        }
        retries = 3;
        do {
                cmd[0] = READ_CAPACITY;
                cmd[1] = (rscsi_disks[i].device->lun << 5) & 0xe0;
                memset((void *) &cmd[2], 0, 8);
                memset((void *) buffer, 0, 8);
                SRpnt->sr_cmd_len = 0;
                SRpnt->sr_sense_buffer[0] = 0;
                SRpnt->sr_sense_buffer[2] = 0;

                SRpnt->sr_data_direction = SCSI_DATA_READ;
                scsi_wait_req(SRpnt, (void *) cmd, (void *) buffer,
                            8, SD_TIMEOUT, MAX_RETRIES);

                the_result = SRpnt->sr_result;
                retries--;

        } while (the_result && retries);

        /*
         * The SCSI standard says:
         * "READ CAPACITY is necessary for self configuring software"
         *  While not mandatory, support of READ CAPACITY is strongly encouraged.
         *  We used to die if we couldn't successfully do a READ CAPACITY.
         *  But, now we go on about our way.  The side effects of this are
         *
         *  1. We can't know block size with certainty. I have said "512 bytes
         *     is it" as this is most common.
         *
         *  2. Recovery from when some one attempts to read past the end of the
         *     raw device will be slower.
         */

        if (the_result) {
                printk("%s : READ CAPACITY failed.\n"
                       "%s : status = %x, message = %02x, host = %d, driver = %02x \n",
                       nbuff, nbuff,
                       status_byte(the_result),
                       msg_byte(the_result),
                       host_byte(the_result),
                       driver_byte(the_result)
                    );
                if (driver_byte(the_result) & DRIVER_SENSE)
                        printk("%s : extended sense code = %1x \n",
                               nbuff, SRpnt->sr_sense_buffer[2] & 0xf);
                else
                        printk("%s : sense not available. \n", nbuff);

                printk("%s : block size assumed to be 512 bytes, disk size 1GB.  \n",
                       nbuff);
                rscsi_disks[i].capacity = 0x1fffff;
                sector_size = 512;

                /* Set dirty bit for removable devices if not ready - sometimes drives
                 * will not report this properly. */
                if (rscsi_disks[i].device->removable &&
                    SRpnt->sr_sense_buffer[2] == NOT_READY)
                        rscsi_disks[i].device->changed = 1;

        } else {
                /*
                 * FLOPTICAL , if read_capa is ok , drive is assumed to be ready
                 */
                rscsi_disks[i].ready = 1;

                rscsi_disks[i].capacity = 1 + ((buffer[0] << 24) |
                                               (buffer[1] << 16) |
                                               (buffer[2] << 8) |
                                               buffer[3]);

                sector_size = (buffer[4] << 24) |
                    (buffer[5] << 16) | (buffer[6] << 8) | buffer[7];

                if (sector_size == 0) {
                        sector_size = 512;
                        printk("%s : sector size 0 reported, assuming 512.\n", nbuff);
                }
                if (sector_size != 512 &&
                    sector_size != 1024 &&
                    sector_size != 2048 &&
                    sector_size != 4096 &&
                    sector_size != 256) {
                        printk("%s : unsupported sector size %d.\n",
                               nbuff, sector_size);
                        /*
                         * The user might want to re-format the drive with
                         * a supported sectorsize.  Once this happens, it
                         * would be relatively trivial to set the thing up.
                         * For this reason, we leave the thing in the table.
                         */
                        rscsi_disks[i].capacity = 0;
                }
                if (sector_size > 1024) {
                        int m;

                        /*
                         * We must fix the sd_blocksizes and sd_hardsizes
                         * to allow us to read the partition tables.
                         * The disk reading code does not allow for reading
                         * of partial sectors.
                         */
                        for (m = i << 4; m < ((i + 1) << 4); m++) {
                                sd_blocksizes[m] = sector_size;
                        }
                } {
                        /*
                         * The msdos fs needs to know the hardware sector size
                         * So I have created this table. See ll_rw_blk.c
                         * Jacques Gelinas (Jacques@solucorp.qc.ca)
                         */
                        int m, mb;
                        int sz_quot, sz_rem;
                        int hard_sector = sector_size;
                        /* There are 16 minors allocated for each major device */
                        for (m = i << 4; m < ((i + 1) << 4); m++) {
                                sd_hardsizes[m] = hard_sector;
                        }
                        mb = rscsi_disks[i].capacity / 1024 * hard_sector / 1024;
                        /* sz = div(m/100, 10);  this seems to not be in the libr */
                        m = (mb + 50) / 100;
                        sz_quot = m / 10;
                        sz_rem = m - (10 * sz_quot);
                        printk("SCSI device %s: hdwr sector= %d bytes."
                               " Sectors= %d [%d MB] [%d.%1d GB]\n",
                             nbuff, hard_sector, rscsi_disks[i].capacity,
                               mb, sz_quot, sz_rem);
                }
                if (sector_size == 4096)
                        rscsi_disks[i].capacity <<= 3;
                if (sector_size == 2048)
                        rscsi_disks[i].capacity <<= 2;  /* Change into 512 byte sectors */
                if (sector_size == 1024)
                        rscsi_disks[i].capacity <<= 1;  /* Change into 512 byte sectors */
                if (sector_size == 256)
                        rscsi_disks[i].capacity >>= 1;  /* Change into 512 byte sectors */
        }


        /*
         * Unless otherwise specified, this is not write protected.
         */
        rscsi_disks[i].write_prot = 0;
        if (rscsi_disks[i].device->removable && rscsi_disks[i].ready) {
                /* FLOPTICAL */

                /*
                 * For removable scsi disk ( FLOPTICAL ) we have to recognise
                 * the Write Protect Flag. This flag is kept in the Scsi_Disk
                 * struct and tested at open !
                 * Daniel Roche ( dan@lectra.fr )
                 *
                 * Changed to get all pages (0x3f) rather than page 1 to
                 * get around devices which do not have a page 1.  Since
                 * we're only interested in the header anyway, this should
                 * be fine.
                 *   -- Matthew Dharm (mdharm-scsi@one-eyed-alien.net)
                 */

                memset((void *) &cmd[0], 0, 8);
                cmd[0] = MODE_SENSE;
                cmd[1] = (rscsi_disks[i].device->lun << 5) & 0xe0;
                cmd[2] = 0x3f;  /* Get all pages */
                cmd[4] = 8;     /* But we only want the 8 byte header */
                SRpnt->sr_cmd_len = 0;
                SRpnt->sr_sense_buffer[0] = 0;
                SRpnt->sr_sense_buffer[2] = 0;

                /* same code as READCAPA !! */
                SRpnt->sr_data_direction = SCSI_DATA_READ;
                scsi_wait_req(SRpnt, (void *) cmd, (void *) buffer,
                            512, SD_TIMEOUT, MAX_RETRIES);

                the_result = SRpnt->sr_result;

                if (the_result) {
                        printk("%s: test WP failed, assume Write Protected\n", nbuff);
                        rscsi_disks[i].write_prot = 1;
                } else {
                        rscsi_disks[i].write_prot = ((buffer[2] & 0x80) != 0);
                        printk("%s: Write Protect is %s\n", nbuff,
                               rscsi_disks[i].write_prot ? "on" : "off");
                }

        }                       /* check for write protect */
        SRpnt->sr_device->ten = 1;
        SRpnt->sr_device->remap = 1;
        SRpnt->sr_device->sector_size = sector_size;
        /* Wake up a process waiting for device */
        scsi_release_request(SRpnt);
        SRpnt = NULL;

        scsi_free(buffer, 512);
        return i;
}

/*
 * The sd_init() function looks at all SCSI drives present, determines
 * their size, and reads partition table entries for them.
 */

static int sd_registered = 0;

static int sd_init()
{
        int i;

        if (sd_template.dev_noticed == 0)
                return 0;

        if (!rscsi_disks)
                sd_template.dev_max = sd_template.dev_noticed + SD_EXTRA_DEVS;

        if (sd_template.dev_max > N_SD_MAJORS * SCSI_DISKS_PER_MAJOR)
                sd_template.dev_max = N_SD_MAJORS * SCSI_DISKS_PER_MAJOR;

        if (!sd_registered) {
                for (i = 0; i <= (sd_template.dev_max - 1) / SCSI_DISKS_PER_MAJOR; i++) {
                        if (devfs_register_blkdev(SD_MAJOR(i), "sd", &sd_fops)) {
                                printk("Unable to get major %d for SCSI disk\n", SD_MAJOR(i));
                                return 1;
                        }
                }
                sd_registered++;
        }
        /* We do not support attaching loadable devices yet. */
        if (rscsi_disks)
                return 0;

        rscsi_disks = (Scsi_Disk *)
            kmalloc(sd_template.dev_max * sizeof(Scsi_Disk), GFP_ATOMIC);
        memset(rscsi_disks, 0, sd_template.dev_max * sizeof(Scsi_Disk));

        /* for every (necessary) major: */
        sd_sizes = (int *) kmalloc((sd_template.dev_max << 4) * sizeof(int), GFP_ATOMIC);
        memset(sd_sizes, 0, (sd_template.dev_max << 4) * sizeof(int));

        sd_blocksizes = (int *) kmalloc((sd_template.dev_max << 4) * sizeof(int), GFP_ATOMIC);
        sd_hardsizes = (int *) kmalloc((sd_template.dev_max << 4) * sizeof(int), GFP_ATOMIC);

        for (i = 0; i < sd_template.dev_max << 4; i++) {
                sd_blocksizes[i] = 1024;
                sd_hardsizes[i] = 512;
        }

        for (i = 0; i < N_USED_SD_MAJORS; i++) {
                blksize_size[SD_MAJOR(i)] = sd_blocksizes + i * (SCSI_DISKS_PER_MAJOR << 4);
                hardsect_size[SD_MAJOR(i)] = sd_hardsizes + i * (SCSI_DISKS_PER_MAJOR << 4);
        }
        sd = (struct hd_struct *) kmalloc((sd_template.dev_max << 4) *
                                          sizeof(struct hd_struct),
                                          GFP_ATOMIC);
        memset(sd, 0, (sd_template.dev_max << 4) * sizeof(struct hd_struct));

        if (N_USED_SD_MAJORS > 1)
                sd_gendisks = (struct gendisk *)
                    kmalloc(N_USED_SD_MAJORS * sizeof(struct gendisk), GFP_ATOMIC);
        for (i = 0; i < N_USED_SD_MAJORS; i++) {
                sd_gendisks[i] = sd_gendisk;
                sd_gendisks[i].de_arr = kmalloc (SCSI_DISKS_PER_MAJOR * sizeof *sd_gendisks[i].de_arr,
                                                 GFP_ATOMIC);
                memset (sd_gendisks[i].de_arr, 0,
                        SCSI_DISKS_PER_MAJOR * sizeof *sd_gendisks[i].de_arr);
                sd_gendisks[i].flags = kmalloc (SCSI_DISKS_PER_MAJOR * sizeof *sd_gendisks[i].flags,
                                                GFP_ATOMIC);
                memset (sd_gendisks[i].flags, 0,
                        SCSI_DISKS_PER_MAJOR * sizeof *sd_gendisks[i].flags);
                sd_gendisks[i].major = SD_MAJOR(i);
                sd_gendisks[i].major_name = "sd";
                sd_gendisks[i].minor_shift = 4;
                sd_gendisks[i].max_p = 1 << 4;
                sd_gendisks[i].part = sd + (i * SCSI_DISKS_PER_MAJOR << 4);
                sd_gendisks[i].sizes = sd_sizes + (i * SCSI_DISKS_PER_MAJOR << 4);
                sd_gendisks[i].nr_real = 0;
                sd_gendisks[i].next = sd_gendisks + i + 1;
                sd_gendisks[i].real_devices =
                    (void *) (rscsi_disks + i * SCSI_DISKS_PER_MAJOR);
        }

        LAST_SD_GENDISK.next = NULL;
        return 0;
}


static void sd_finish()
{
        struct gendisk *gendisk;
        int i;

        for (i = 0; i <= (sd_template.dev_max - 1) / SCSI_DISKS_PER_MAJOR; i++) {
                blk_dev[SD_MAJOR(i)].queue = sd_find_queue;
        }
        for (gendisk = gendisk_head; gendisk != NULL; gendisk = gendisk->next)
                if (gendisk == sd_gendisks)
                        break;
        if (gendisk == NULL) {
                LAST_SD_GENDISK.next = gendisk_head;
                gendisk_head = sd_gendisks;
        }
        for (i = 0; i < sd_template.dev_max; ++i)
                if (!rscsi_disks[i].capacity && rscsi_disks[i].device) {
                        sd_init_onedisk(i);
                        if (!rscsi_disks[i].has_part_table) {
                                sd_sizes[i << 4] = rscsi_disks[i].capacity;
                                register_disk(&SD_GENDISK(i), MKDEV_SD(i),
                                                1<<4, &sd_fops,
                                                rscsi_disks[i].capacity);
                                rscsi_disks[i].has_part_table = 1;
                        }
                }
        /* If our host adapter is capable of scatter-gather, then we increase
         * the read-ahead to 60 blocks (120 sectors).  If not, we use
         * a two block (4 sector) read ahead. We can only respect this with the
         * granularity of every 16 disks (one device major).
         */
        for (i = 0; i < N_USED_SD_MAJORS; i++) {
                read_ahead[SD_MAJOR(i)] =
                    (rscsi_disks[i * SCSI_DISKS_PER_MAJOR].device
                     && rscsi_disks[i * SCSI_DISKS_PER_MAJOR].device->host->sg_tablesize)
                    ? 120       /* 120 sector read-ahead */
                    : 4;        /* 4 sector read-ahead */
        }

        return;
}

static int sd_detect(Scsi_Device * SDp)
{
        char nbuff[6];
        if (SDp->type != TYPE_DISK && SDp->type != TYPE_MOD)
                return 0;

        sd_devname(sd_template.dev_noticed++, nbuff);
        printk("Detected scsi %sdisk %s at scsi%d, channel %d, id %d, lun %d\n",
               SDp->removable ? "removable " : "",
               nbuff,
               SDp->host->host_no, SDp->channel, SDp->id, SDp->lun);

        return 1;
}

static int sd_attach(Scsi_Device * SDp)
{
        unsigned int devnum;
        Scsi_Disk *dpnt;
        int i;

        if (SDp->type != TYPE_DISK && SDp->type != TYPE_MOD)
                return 0;

        if (sd_template.nr_dev >= sd_template.dev_max) {
                SDp->attached--;
                return 1;
        }
        for (dpnt = rscsi_disks, i = 0; i < sd_template.dev_max; i++, dpnt++)
                if (!dpnt->device)
                        break;

        if (i >= sd_template.dev_max)
                panic("scsi_devices corrupt (sd)");

        rscsi_disks[i].device = SDp;
        rscsi_disks[i].has_part_table = 0;
        sd_template.nr_dev++;
        SD_GENDISK(i).nr_real++;
        devnum = i % SCSI_DISKS_PER_MAJOR;
        SD_GENDISK(i).de_arr[devnum] = SDp->de;
        if (SDp->removable)
                SD_GENDISK(i).flags[devnum] |= GENHD_FL_REMOVABLE;
        return 0;
}

#define DEVICE_BUSY rscsi_disks[target].device->busy
#define USAGE rscsi_disks[target].device->access_count
#define CAPACITY rscsi_disks[target].capacity
#define MAYBE_REINIT  sd_init_onedisk(target)

/* This routine is called to flush all partitions and partition tables
 * for a changed scsi disk, and then re-read the new partition table.
 * If we are revalidating a disk because of a media change, then we
 * enter with usage == 0.  If we are using an ioctl, we automatically have
 * usage == 1 (we need an open channel to use an ioctl :-), so this
 * is our limit.
 */
int revalidate_scsidisk(kdev_t dev, int maxusage)
{
        int target;
        int max_p;
        int start;
        int i;

        target = DEVICE_NR(dev);

        if (DEVICE_BUSY || USAGE > maxusage) {
                printk("Device busy for revalidation (usage=%d)\n", USAGE);
                return -EBUSY;
        }
        DEVICE_BUSY = 1;

        max_p = sd_gendisks->max_p;
        start = target << sd_gendisks->minor_shift;

        for (i = max_p - 1; i >= 0; i--) {
                int index = start + i;
                kdev_t devi = MKDEV_SD_PARTITION(index);
                struct super_block *sb = get_super(devi);
                sync_dev(devi);
                if (sb)
                        invalidate_inodes(sb);
                invalidate_buffers(devi);
                sd_gendisks->part[index].start_sect = 0;
                sd_gendisks->part[index].nr_sects = 0;
                /*
                 * Reset the blocksize for everything so that we can read
                 * the partition table.  Technically we will determine the
                 * correct block size when we revalidate, but we do this just
                 * to make sure that everything remains consistent.
                 */
                sd_blocksizes[index] = 1024;
                if (rscsi_disks[target].device->sector_size == 2048)
                        sd_blocksizes[index] = 2048;
                else
                        sd_blocksizes[index] = 1024;
        }

#ifdef MAYBE_REINIT
        MAYBE_REINIT;
#endif

        grok_partitions(&SD_GENDISK(target), target % SCSI_DISKS_PER_MAJOR,
                        1<<4, CAPACITY);

        DEVICE_BUSY = 0;
        return 0;
}

static int fop_revalidate_scsidisk(kdev_t dev)
{
        return revalidate_scsidisk(dev, 0);
}
static void sd_detach(Scsi_Device * SDp)
{
        Scsi_Disk *dpnt;
        int i, j;
        int max_p;
        int start;

        for (dpnt = rscsi_disks, i = 0; i < sd_template.dev_max; i++, dpnt++)
                if (dpnt->device == SDp) {

                        /* If we are disconnecting a disk driver, sync and invalidate
                         * everything */
                        max_p = sd_gendisk.max_p;
                        start = i << sd_gendisk.minor_shift;

                        for (j = max_p - 1; j >= 0; j--) {
                                int index = start + j;
                                kdev_t devi = MKDEV_SD_PARTITION(index);
                                struct super_block *sb = get_super(devi);
                                sync_dev(devi);
                                if (sb)
                                        invalidate_inodes(sb);
                                invalidate_buffers(devi);
                                sd_gendisks->part[index].start_sect = 0;
                                sd_gendisks->part[index].nr_sects = 0;
                                sd_sizes[index] = 0;
                        }
                        devfs_register_partitions (&SD_GENDISK (i),
                                                   SD_MINOR_NUMBER (start), 1);
                        /* unregister_disk() */
                        dpnt->has_part_table = 0;
                        dpnt->device = NULL;
                        dpnt->capacity = 0;
                        SDp->attached--;
                        sd_template.dev_noticed--;
                        sd_template.nr_dev--;
                        SD_GENDISK(i).nr_real--;
                        return;
                }
        return;
}

#ifdef MODULE

int init_module(void)
{
        sd_template.module = &__this_module;
        return scsi_register_module(MODULE_SCSI_DEV, &sd_template);
}
void cleanup_module(void)
{
        struct gendisk **prev_sdgd_link;
        struct gendisk *sdgd;
        int i;
        int removed = 0;

        scsi_unregister_module(MODULE_SCSI_DEV, &sd_template);

        for (i = 0; i <= (sd_template.dev_max - 1) / SCSI_DISKS_PER_MAJOR; i++)
                devfs_unregister_blkdev(SD_MAJOR(i), "sd");

        sd_registered--;
        if (rscsi_disks != NULL) {
                kfree((char *) rscsi_disks);
                kfree((char *) sd_sizes);
                kfree((char *) sd_blocksizes);
                kfree((char *) sd_hardsizes);
                kfree((char *) sd);

                /*
                 * Now remove sd_gendisks from the linked list
                 */
                prev_sdgd_link = &gendisk_head;
                while ((sdgd = *prev_sdgd_link) != NULL) {
                        if (sdgd >= sd_gendisks && sdgd <= &LAST_SD_GENDISK) {
                                removed++;
                                *prev_sdgd_link = sdgd->next;
                                continue;
                        }
                        prev_sdgd_link = &sdgd->next;
                }

                if (removed != N_USED_SD_MAJORS)
                        printk("%s %d sd_gendisks in disk chain",
                               removed > N_USED_SD_MAJORS ? "total" : "just", removed);

        }
        for (i = 0; i <= (sd_template.dev_max - 1) / SCSI_DISKS_PER_MAJOR; i++) {
                blk_size[SD_MAJOR(i)] = NULL;
                hardsect_size[SD_MAJOR(i)] = NULL;
                read_ahead[SD_MAJOR(i)] = 0;
        }
        sd_template.dev_max = 0;
        if (sd_gendisks != &sd_gendisk)
                kfree(sd_gendisks);
}
#endif                          /* MODULE */

/*
 * Overrides for Emacs so that we almost follow Linus's tabbing style.
 * Emacs will notice this stuff at the end of the file and automatically
 * adjust the settings for this buffer only.  This must remain at the end
 * of the file.
 * ---------------------------------------------------------------------------
 * Local variables:
 * c-indent-level: 4
 * c-brace-imaginary-offset: 0
 * c-brace-offset: -4
 * c-argdecl-indent: 4
 * c-label-offset: -4
 * c-continued-statement-offset: 4
 * c-continued-brace-offset: 0
 * indent-tabs-mode: nil
 * tab-width: 8
 * End:
 */