simscsi.c

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/*
 * Simulated SCSI driver.
 *
 * Copyright (C) 1999, 2001-2003 Hewlett-Packard Co
 *  David Mosberger-Tang <[email protected]>
 *  Stephane Eranian <[email protected]>
 *
 * 02/01/15 David Mosberger Updated for v2.5.1
 * 99/12/18 David Mosberger Added support for READ10/WRITE10 needed by linux v2.3.33
 */
#include <linux/blkdev.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <asm/irq.h>
#include "hpsim_ssc.h"

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>

#define DEBUG_SIMSCSI   0

#define SIMSCSI_REQ_QUEUE_LEN   64
#define DEFAULT_SIMSCSI_ROOT    "/var/ski-disks/sd"

/* Simulator system calls: */

#define SSC_OPEN            50
#define SSC_CLOSE           51
#define SSC_READ            52
#define SSC_WRITE           53
#define SSC_GET_COMPLETION      54
#define SSC_WAIT_COMPLETION     55

#define SSC_WRITE_ACCESS        2
#define SSC_READ_ACCESS         1

#if DEBUG_SIMSCSI
  int simscsi_debug;
# define DBG    simscsi_debug
#else
# define DBG    0
#endif

static struct Scsi_Host *host;

static void simscsi_interrupt (unsigned long val);
static DECLARE_TASKLET(simscsi_tasklet, simscsi_interrupt, 0);

struct disk_req {
    unsigned long addr;
    unsigned len;
};

struct disk_stat {
    int fd;
    unsigned count;
};

static int desc[16] = {
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
};

static struct queue_entry {
    struct scsi_cmnd *sc;
} queue[SIMSCSI_REQ_QUEUE_LEN];

static int rd, wr;
static atomic_t num_reqs = ATOMIC_INIT(0);

/* base name for default disks */
static char *simscsi_root = DEFAULT_SIMSCSI_ROOT;

#define MAX_ROOT_LEN    128

/*
 * used to setup a new base for disk images
 * to use /foo/bar/disk[a-z] as disk images
 * you have to specify simscsi=/foo/bar/disk on the command line
 */
static int __init
simscsi_setup (char *s)
{
    /* XXX Fix me we may need to strcpy() ? */
    if (strlen(s) > MAX_ROOT_LEN) {
        printk(KERN_ERR "simscsi_setup: prefix too long---using default %s\n",
               simscsi_root);
    }
    simscsi_root = s;
    return 1;
}

__setup("simscsi=", simscsi_setup);

static void
simscsi_interrupt (unsigned long val)
{
    struct scsi_cmnd *sc;

    while ((sc = queue[rd].sc) != NULL) {
        atomic_dec(&num_reqs);
        queue[rd].sc = NULL;
        if (DBG)
            printk("simscsi_interrupt: done with %ld\n", sc->serial_number);
        (*sc->scsi_done)(sc);
        rd = (rd + 1) % SIMSCSI_REQ_QUEUE_LEN;
    }
}

static int
simscsi_biosparam (struct scsi_device *sdev, struct block_device *n,
        sector_t capacity, int ip[])
{
    ip[0] = 64;     /* heads */
    ip[1] = 32;     /* sectors */
    ip[2] = capacity >> 11; /* cylinders */
    return 0;
}

static void
simscsi_sg_readwrite (struct scsi_cmnd *sc, int mode, unsigned long offset)
{
    int i;
    struct scatterlist *sl;
    struct disk_stat stat;
    struct disk_req req;

    stat.fd = desc[sc->device->id];

    scsi_for_each_sg(sc, sl, scsi_sg_count(sc), i) {
        req.addr = __pa(sg_virt(sl));
        req.len  = sl->length;
        if (DBG)
            printk("simscsi_sg_%s @ %lx (off %lx) use_sg=%d len=%d\n",
                   mode == SSC_READ ? "read":"write", req.addr, offset,
                   scsi_sg_count(sc) - i, sl->length);
        ia64_ssc(stat.fd, 1, __pa(&req), offset, mode);
        ia64_ssc(__pa(&stat), 0, 0, 0, SSC_WAIT_COMPLETION);

        /* should not happen in our case */
        if (stat.count != req.len) {
            sc->result = DID_ERROR << 16;
            return;
        }
        offset +=  sl->length;
    }
    sc->result = GOOD;
}

/*
 * function handling both READ_6/WRITE_6 (non-scatter/gather mode)
 * commands.
 * Added 02/26/99 S.Eranian
 */
static void
simscsi_readwrite6 (struct scsi_cmnd *sc, int mode)
{
    unsigned long offset;

    offset = (((sc->cmnd[1] & 0x1f) << 16) | (sc->cmnd[2] << 8) | sc->cmnd[3])*512;
    simscsi_sg_readwrite(sc, mode, offset);
}

static size_t
simscsi_get_disk_size (int fd)
{
    struct disk_stat stat;
    size_t bit, sectors = 0;
    struct disk_req req;
    char buf[512];

    /*
     * This is a bit kludgey: the simulator doesn't provide a
     * direct way of determining the disk size, so we do a binary
     * search, assuming a maximum disk size of 128GB.
     */
    for (bit = (128UL << 30)/512; bit != 0; bit >>= 1) {
        req.addr = __pa(&buf);
        req.len = sizeof(buf);
        ia64_ssc(fd, 1, __pa(&req), ((sectors | bit) - 1)*512, SSC_READ);
        stat.fd = fd;
        ia64_ssc(__pa(&stat), 0, 0, 0, SSC_WAIT_COMPLETION);
        if (stat.count == sizeof(buf))
            sectors |= bit;
    }
    return sectors - 1; /* return last valid sector number */
}

static void
simscsi_readwrite10 (struct scsi_cmnd *sc, int mode)
{
    unsigned long offset;

    offset = (((unsigned long)sc->cmnd[2] << 24) 
        | ((unsigned long)sc->cmnd[3] << 16)
        | ((unsigned long)sc->cmnd[4] <<  8) 
        | ((unsigned long)sc->cmnd[5] <<  0))*512UL;
    simscsi_sg_readwrite(sc, mode, offset);
}

static int
simscsi_queuecommand_lck (struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
{
    unsigned int target_id = sc->device->id;
    char fname[MAX_ROOT_LEN+16];
    size_t disk_size;
    char *buf;
    char localbuf[36];
#if DEBUG_SIMSCSI
    register long sp asm ("sp");

    if (DBG)
        printk("simscsi_queuecommand: target=%d,cmnd=%u,sc=%lu,sp=%lx,done=%p\n",
               target_id, sc->cmnd[0], sc->serial_number, sp, done);
#endif

    sc->result = DID_BAD_TARGET << 16;
    sc->scsi_done = done;
    if (target_id <= 15 && sc->device->lun == 0) {
        switch (sc->cmnd[0]) {
              case INQUIRY:
            if (scsi_bufflen(sc) < 35) {
                break;
            }
            sprintf (fname, "%s%c", simscsi_root, 'a' + target_id);
            desc[target_id] = ia64_ssc(__pa(fname), SSC_READ_ACCESS|SSC_WRITE_ACCESS,
                           0, 0, SSC_OPEN);
            if (desc[target_id] < 0) {
                /* disk doesn't exist... */
                break;
            }
            buf = localbuf;
            buf[0] = 0; /* magnetic disk */
            buf[1] = 0; /* not a removable medium */
            buf[2] = 2; /* SCSI-2 compliant device */
            buf[3] = 2; /* SCSI-2 response data format */
            buf[4] = 31;    /* additional length (bytes) */
            buf[5] = 0; /* reserved */
            buf[6] = 0; /* reserved */
            buf[7] = 0; /* various flags */
            memcpy(buf + 8, "HP      SIMULATED DISK  0.00",  28);
            scsi_sg_copy_from_buffer(sc, buf, 36);
            sc->result = GOOD;
            break;

              case TEST_UNIT_READY:
            sc->result = GOOD;
            break;

              case READ_6:
            if (desc[target_id] < 0 )
                break;
            simscsi_readwrite6(sc, SSC_READ);
            break;

              case READ_10:
            if (desc[target_id] < 0 )
                break;
            simscsi_readwrite10(sc, SSC_READ);
            break;

              case WRITE_6:
            if (desc[target_id] < 0)
                break;
            simscsi_readwrite6(sc, SSC_WRITE);
            break;

              case WRITE_10:
            if (desc[target_id] < 0)
                break;
            simscsi_readwrite10(sc, SSC_WRITE);
            break;

              case READ_CAPACITY:
            if (desc[target_id] < 0 || scsi_bufflen(sc) < 8) {
                break;
            }
            buf = localbuf;
            disk_size = simscsi_get_disk_size(desc[target_id]);

            buf[0] = (disk_size >> 24) & 0xff;
            buf[1] = (disk_size >> 16) & 0xff;
            buf[2] = (disk_size >>  8) & 0xff;
            buf[3] = (disk_size >>  0) & 0xff;
            /* set block size of 512 bytes: */
            buf[4] = 0;
            buf[5] = 0;
            buf[6] = 2;
            buf[7] = 0;
            scsi_sg_copy_from_buffer(sc, buf, 8);
            sc->result = GOOD;
            break;

              case MODE_SENSE:
              case MODE_SENSE_10:
            /* sd.c uses this to determine whether disk does write-caching. */
            scsi_sg_copy_from_buffer(sc, (char *)empty_zero_page,
                         PAGE_SIZE);
            sc->result = GOOD;
            break;

              case START_STOP:
            printk(KERN_ERR "START_STOP\n");
            break;

              default:
            panic("simscsi: unknown SCSI command %u\n", sc->cmnd[0]);
        }
    }
    if (sc->result == DID_BAD_TARGET) {
        sc->result |= DRIVER_SENSE << 24;
        sc->sense_buffer[0] = 0x70;
        sc->sense_buffer[2] = 0x00;
    }
    if (atomic_read(&num_reqs) >= SIMSCSI_REQ_QUEUE_LEN) {
        panic("Attempt to queue command while command is pending!!");
    }
    atomic_inc(&num_reqs);
    queue[wr].sc = sc;
    wr = (wr + 1) % SIMSCSI_REQ_QUEUE_LEN;

    tasklet_schedule(&simscsi_tasklet);
    return 0;
}

static DEF_SCSI_QCMD(simscsi_queuecommand)

static int
simscsi_host_reset (struct scsi_cmnd *sc)
{
    printk(KERN_ERR "simscsi_host_reset: not implemented\n");
    return 0;
}

static struct scsi_host_template driver_template = {
    .name           = "simulated SCSI host adapter",
    .proc_name      = "simscsi",
    .queuecommand       = simscsi_queuecommand,
    .eh_host_reset_handler  = simscsi_host_reset,
    .bios_param     = simscsi_biosparam,
    .can_queue      = SIMSCSI_REQ_QUEUE_LEN,
    .this_id        = -1,
    .sg_tablesize       = SG_ALL,
    .max_sectors        = 1024,
    .cmd_per_lun        = SIMSCSI_REQ_QUEUE_LEN,
    .use_clustering     = DISABLE_CLUSTERING,
};

static int __init
simscsi_init(void)
{
    int error;

    host = scsi_host_alloc(&driver_template, 0);
    if (!host)
        return -ENOMEM;

    error = scsi_add_host(host, NULL);
    if (error)
        goto free_host;
    scsi_scan_host(host);
    return 0;

 free_host:
    scsi_host_put(host);
    return error;
}

static void __exit
simscsi_exit(void)
{
    scsi_remove_host(host);
    scsi_host_put(host);
}

module_init(simscsi_init);
module_exit(simscsi_exit);