imm.c

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/* imm.c   --  low level driver for the IOMEGA MatchMaker
 * parallel port SCSI host adapter.
 * 
 * (The IMM is the embedded controller in the ZIP Plus drive.)
 * 
 * My unofficial company acronym list is 21 pages long:
 *      FLA:    Four letter acronym with built in facility for
 *              future expansion to five letters.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/parport.h>
#include <linux/workqueue.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <asm/io.h>

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

/* The following #define is to avoid a clash with hosts.c */
#define IMM_PROBE_SPP   0x0001
#define IMM_PROBE_PS2   0x0002
#define IMM_PROBE_ECR   0x0010
#define IMM_PROBE_EPP17 0x0100
#define IMM_PROBE_EPP19 0x0200


typedef struct {
    struct pardevice *dev;  /* Parport device entry         */
    int base;       /* Actual port address          */
    int base_hi;        /* Hi Base address for ECP-ISA chipset */
    int mode;       /* Transfer mode                */
    struct scsi_cmnd *cur_cmd;  /* Current queued command       */
    struct delayed_work imm_tq; /* Polling interrupt stuff       */
    unsigned long jstart;   /* Jiffies at start             */
    unsigned failed:1;  /* Failure flag                 */
    unsigned dp:1;      /* Data phase present           */
    unsigned rd:1;      /* Read data in data phase      */
    unsigned wanted:1;  /* Parport sharing busy flag    */
    wait_queue_head_t *waiting;
    struct Scsi_Host *host;
    struct list_head list;
} imm_struct;

static void imm_reset_pulse(unsigned int base);
static int device_check(imm_struct *dev);

#include "imm.h"

static inline imm_struct *imm_dev(struct Scsi_Host *host)
{
    return *(imm_struct **)&host->hostdata;
}

static DEFINE_SPINLOCK(arbitration_lock);

static void got_it(imm_struct *dev)
{
    dev->base = dev->dev->port->base;
    if (dev->cur_cmd)
        dev->cur_cmd->SCp.phase = 1;
    else
        wake_up(dev->waiting);
}

static void imm_wakeup(void *ref)
{
    imm_struct *dev = (imm_struct *) ref;
    unsigned long flags;

    spin_lock_irqsave(&arbitration_lock, flags);
    if (dev->wanted) {
        parport_claim(dev->dev);
        got_it(dev);
        dev->wanted = 0;
    }
    spin_unlock_irqrestore(&arbitration_lock, flags);
}

static int imm_pb_claim(imm_struct *dev)
{
    unsigned long flags;
    int res = 1;
    spin_lock_irqsave(&arbitration_lock, flags);
    if (parport_claim(dev->dev) == 0) {
        got_it(dev);
        res = 0;
    }
    dev->wanted = res;
    spin_unlock_irqrestore(&arbitration_lock, flags);
    return res;
}

static void imm_pb_dismiss(imm_struct *dev)
{
    unsigned long flags;
    int wanted;
    spin_lock_irqsave(&arbitration_lock, flags);
    wanted = dev->wanted;
    dev->wanted = 0;
    spin_unlock_irqrestore(&arbitration_lock, flags);
    if (!wanted)
        parport_release(dev->dev);
}

static inline void imm_pb_release(imm_struct *dev)
{
    parport_release(dev->dev);
}

/* This is to give the imm driver a way to modify the timings (and other
 * parameters) by writing to the /proc/scsi/imm/0 file.
 * Very simple method really... (Too simple, no error checking :( )
 * Reason: Kernel hackers HATE having to unload and reload modules for
 * testing...
 * Also gives a method to use a script to obtain optimum timings (TODO)
 */
static inline int imm_proc_write(imm_struct *dev, char *buffer, int length)
{
    unsigned long x;

    if ((length > 5) && (strncmp(buffer, "mode=", 5) == 0)) {
        x = simple_strtoul(buffer + 5, NULL, 0);
        dev->mode = x;
        return length;
    }
    printk("imm /proc: invalid variable\n");
    return (-EINVAL);
}

static int imm_proc_info(struct Scsi_Host *host, char *buffer, char **start,
            off_t offset, int length, int inout)
{
    imm_struct *dev = imm_dev(host);
    int len = 0;

    if (inout)
        return imm_proc_write(dev, buffer, length);

    len += sprintf(buffer + len, "Version : %s\n", IMM_VERSION);
    len +=
        sprintf(buffer + len, "Parport : %s\n",
            dev->dev->port->name);
    len +=
        sprintf(buffer + len, "Mode    : %s\n",
            IMM_MODE_STRING[dev->mode]);

    /* Request for beyond end of buffer */
    if (offset > len)
        return 0;

    *start = buffer + offset;
    len -= offset;
    if (len > length)
        len = length;
    return len;
}

#if IMM_DEBUG > 0
#define imm_fail(x,y) printk("imm: imm_fail(%i) from %s at line %d\n",\
       y, __func__, __LINE__); imm_fail_func(x,y);
static inline void
imm_fail_func(imm_struct *dev, int error_code)
#else
static inline void
imm_fail(imm_struct *dev, int error_code)
#endif
{
    /* If we fail a device then we trash status / message bytes */
    if (dev->cur_cmd) {
        dev->cur_cmd->result = error_code << 16;
        dev->failed = 1;
    }
}

/*
 * Wait for the high bit to be set.
 * 
 * In principle, this could be tied to an interrupt, but the adapter
 * doesn't appear to be designed to support interrupts.  We spin on
 * the 0x80 ready bit. 
 */
static unsigned char imm_wait(imm_struct *dev)
{
    int k;
    unsigned short ppb = dev->base;
    unsigned char r;

    w_ctr(ppb, 0x0c);

    k = IMM_SPIN_TMO;
    do {
        r = r_str(ppb);
        k--;
        udelay(1);
    }
    while (!(r & 0x80) && (k));

    /*
     * STR register (LPT base+1) to SCSI mapping:
     *
     * STR      imm     imm
     * ===================================
     * 0x80     S_REQ   S_REQ
     * 0x40     !S_BSY  (????)
     * 0x20     !S_CD   !S_CD
     * 0x10     !S_IO   !S_IO
     * 0x08     (????)  !S_BSY
     *
     * imm      imm     meaning
     * ==================================
     * 0xf0     0xb8    Bit mask
     * 0xc0     0x88    ZIP wants more data
     * 0xd0     0x98    ZIP wants to send more data
     * 0xe0     0xa8    ZIP is expecting SCSI command data
     * 0xf0     0xb8    end of transfer, ZIP is sending status
     */
    w_ctr(ppb, 0x04);
    if (k)
        return (r & 0xb8);

    /* Counter expired - Time out occurred */
    imm_fail(dev, DID_TIME_OUT);
    printk("imm timeout in imm_wait\n");
    return 0;       /* command timed out */
}

static int imm_negotiate(imm_struct * tmp)
{
    /*
     * The following is supposedly the IEEE 1284-1994 negotiate
     * sequence. I have yet to obtain a copy of the above standard
     * so this is a bit of a guess...
     *
     * A fair chunk of this is based on the Linux parport implementation
     * of IEEE 1284.
     *
     * Return 0 if data available
     *        1 if no data available
     */

    unsigned short base = tmp->base;
    unsigned char a, mode;

    switch (tmp->mode) {
    case IMM_NIBBLE:
        mode = 0x00;
        break;
    case IMM_PS2:
        mode = 0x01;
        break;
    default:
        return 0;
    }

    w_ctr(base, 0x04);
    udelay(5);
    w_dtr(base, mode);
    udelay(100);
    w_ctr(base, 0x06);
    udelay(5);
    a = (r_str(base) & 0x20) ? 0 : 1;
    udelay(5);
    w_ctr(base, 0x07);
    udelay(5);
    w_ctr(base, 0x06);

    if (a) {
        printk
            ("IMM: IEEE1284 negotiate indicates no data available.\n");
        imm_fail(tmp, DID_ERROR);
    }
    return a;
}

/* 
 * Clear EPP timeout bit. 
 */
static inline void epp_reset(unsigned short ppb)
{
    int i;

    i = r_str(ppb);
    w_str(ppb, i);
    w_str(ppb, i & 0xfe);
}

/* 
 * Wait for empty ECP fifo (if we are in ECP fifo mode only)
 */
static inline void ecp_sync(imm_struct *dev)
{
    int i, ppb_hi = dev->base_hi;

    if (ppb_hi == 0)
        return;

    if ((r_ecr(ppb_hi) & 0xe0) == 0x60) {   /* mode 011 == ECP fifo mode */
        for (i = 0; i < 100; i++) {
            if (r_ecr(ppb_hi) & 0x01)
                return;
            udelay(5);
        }
        printk("imm: ECP sync failed as data still present in FIFO.\n");
    }
}

static int imm_byte_out(unsigned short base, const char *buffer, int len)
{
    int i;

    w_ctr(base, 0x4);   /* apparently a sane mode */
    for (i = len >> 1; i; i--) {
        w_dtr(base, *buffer++);
        w_ctr(base, 0x5);   /* Drop STROBE low */
        w_dtr(base, *buffer++);
        w_ctr(base, 0x0);   /* STROBE high + INIT low */
    }
    w_ctr(base, 0x4);   /* apparently a sane mode */
    return 1;       /* All went well - we hope! */
}

static int imm_nibble_in(unsigned short base, char *buffer, int len)
{
    unsigned char l;
    int i;

    /*
     * The following is based on documented timing signals
     */
    w_ctr(base, 0x4);
    for (i = len; i; i--) {
        w_ctr(base, 0x6);
        l = (r_str(base) & 0xf0) >> 4;
        w_ctr(base, 0x5);
        *buffer++ = (r_str(base) & 0xf0) | l;
        w_ctr(base, 0x4);
    }
    return 1;       /* All went well - we hope! */
}

static int imm_byte_in(unsigned short base, char *buffer, int len)
{
    int i;

    /*
     * The following is based on documented timing signals
     */
    w_ctr(base, 0x4);
    for (i = len; i; i--) {
        w_ctr(base, 0x26);
        *buffer++ = r_dtr(base);
        w_ctr(base, 0x25);
    }
    return 1;       /* All went well - we hope! */
}

static int imm_out(imm_struct *dev, char *buffer, int len)
{
    unsigned short ppb = dev->base;
    int r = imm_wait(dev);

    /*
     * Make sure that:
     * a) the SCSI bus is BUSY (device still listening)
     * b) the device is listening
     */
    if ((r & 0x18) != 0x08) {
        imm_fail(dev, DID_ERROR);
        printk("IMM: returned SCSI status %2x\n", r);
        return 0;
    }
    switch (dev->mode) {
    case IMM_EPP_32:
    case IMM_EPP_16:
    case IMM_EPP_8:
        epp_reset(ppb);
        w_ctr(ppb, 0x4);
#ifdef CONFIG_SCSI_IZIP_EPP16
        if (!(((long) buffer | len) & 0x01))
            outsw(ppb + 4, buffer, len >> 1);
#else
        if (!(((long) buffer | len) & 0x03))
            outsl(ppb + 4, buffer, len >> 2);
#endif
        else
            outsb(ppb + 4, buffer, len);
        w_ctr(ppb, 0xc);
        r = !(r_str(ppb) & 0x01);
        w_ctr(ppb, 0xc);
        ecp_sync(dev);
        break;

    case IMM_NIBBLE:
    case IMM_PS2:
        /* 8 bit output, with a loop */
        r = imm_byte_out(ppb, buffer, len);
        break;

    default:
        printk("IMM: bug in imm_out()\n");
        r = 0;
    }
    return r;
}

static int imm_in(imm_struct *dev, char *buffer, int len)
{
    unsigned short ppb = dev->base;
    int r = imm_wait(dev);

    /*
     * Make sure that:
     * a) the SCSI bus is BUSY (device still listening)
     * b) the device is sending data
     */
    if ((r & 0x18) != 0x18) {
        imm_fail(dev, DID_ERROR);
        return 0;
    }
    switch (dev->mode) {
    case IMM_NIBBLE:
        /* 4 bit input, with a loop */
        r = imm_nibble_in(ppb, buffer, len);
        w_ctr(ppb, 0xc);
        break;

    case IMM_PS2:
        /* 8 bit input, with a loop */
        r = imm_byte_in(ppb, buffer, len);
        w_ctr(ppb, 0xc);
        break;

    case IMM_EPP_32:
    case IMM_EPP_16:
    case IMM_EPP_8:
        epp_reset(ppb);
        w_ctr(ppb, 0x24);
#ifdef CONFIG_SCSI_IZIP_EPP16
        if (!(((long) buffer | len) & 0x01))
            insw(ppb + 4, buffer, len >> 1);
#else
        if (!(((long) buffer | len) & 0x03))
            insl(ppb + 4, buffer, len >> 2);
#endif
        else
            insb(ppb + 4, buffer, len);
        w_ctr(ppb, 0x2c);
        r = !(r_str(ppb) & 0x01);
        w_ctr(ppb, 0x2c);
        ecp_sync(dev);
        break;

    default:
        printk("IMM: bug in imm_ins()\n");
        r = 0;
        break;
    }
    return r;
}

static int imm_cpp(unsigned short ppb, unsigned char b)
{
    /*
     * Comments on udelay values refer to the
     * Command Packet Protocol (CPP) timing diagram.
     */

    unsigned char s1, s2, s3;
    w_ctr(ppb, 0x0c);
    udelay(2);      /* 1 usec - infinite */
    w_dtr(ppb, 0xaa);
    udelay(10);     /* 7 usec - infinite */
    w_dtr(ppb, 0x55);
    udelay(10);     /* 7 usec - infinite */
    w_dtr(ppb, 0x00);
    udelay(10);     /* 7 usec - infinite */
    w_dtr(ppb, 0xff);
    udelay(10);     /* 7 usec - infinite */
    s1 = r_str(ppb) & 0xb8;
    w_dtr(ppb, 0x87);
    udelay(10);     /* 7 usec - infinite */
    s2 = r_str(ppb) & 0xb8;
    w_dtr(ppb, 0x78);
    udelay(10);     /* 7 usec - infinite */
    s3 = r_str(ppb) & 0x38;
    /*
     * Values for b are:
     * 0000 00aa    Assign address aa to current device
     * 0010 00aa    Select device aa in EPP Winbond mode
     * 0010 10aa    Select device aa in EPP mode
     * 0011 xxxx    Deselect all devices
     * 0110 00aa    Test device aa
     * 1101 00aa    Select device aa in ECP mode
     * 1110 00aa    Select device aa in Compatible mode
     */
    w_dtr(ppb, b);
    udelay(2);      /* 1 usec - infinite */
    w_ctr(ppb, 0x0c);
    udelay(10);     /* 7 usec - infinite */
    w_ctr(ppb, 0x0d);
    udelay(2);      /* 1 usec - infinite */
    w_ctr(ppb, 0x0c);
    udelay(10);     /* 7 usec - infinite */
    w_dtr(ppb, 0xff);
    udelay(10);     /* 7 usec - infinite */

    /*
     * The following table is electrical pin values.
     * (BSY is inverted at the CTR register)
     *
     *       BSY  ACK  POut SEL  Fault
     * S1    0    X    1    1    1
     * S2    1    X    0    1    1
     * S3    L    X    1    1    S
     *
     * L => Last device in chain
     * S => Selected
     *
     * Observered values for S1,S2,S3 are:
     * Disconnect => f8/58/78
     * Connect    => f8/58/70
     */
    if ((s1 == 0xb8) && (s2 == 0x18) && (s3 == 0x30))
        return 1;   /* Connected */
    if ((s1 == 0xb8) && (s2 == 0x18) && (s3 == 0x38))
        return 0;   /* Disconnected */

    return -1;      /* No device present */
}

static inline int imm_connect(imm_struct *dev, int flag)
{
    unsigned short ppb = dev->base;

    imm_cpp(ppb, 0xe0); /* Select device 0 in compatible mode */
    imm_cpp(ppb, 0x30); /* Disconnect all devices */

    if ((dev->mode == IMM_EPP_8) ||
        (dev->mode == IMM_EPP_16) ||
        (dev->mode == IMM_EPP_32))
        return imm_cpp(ppb, 0x28);  /* Select device 0 in EPP mode */
    return imm_cpp(ppb, 0xe0);  /* Select device 0 in compatible mode */
}

static void imm_disconnect(imm_struct *dev)
{
    imm_cpp(dev->base, 0x30);   /* Disconnect all devices */
}

static int imm_select(imm_struct *dev, int target)
{
    int k;
    unsigned short ppb = dev->base;

    /*
     * Firstly we want to make sure there is nothing
     * holding onto the SCSI bus.
     */
    w_ctr(ppb, 0xc);

    k = IMM_SELECT_TMO;
    do {
        k--;
    } while ((r_str(ppb) & 0x08) && (k));

    if (!k)
        return 0;

    /*
     * Now assert the SCSI ID (HOST and TARGET) on the data bus
     */
    w_ctr(ppb, 0x4);
    w_dtr(ppb, 0x80 | (1 << target));
    udelay(1);

    /*
     * Deassert SELIN first followed by STROBE
     */
    w_ctr(ppb, 0xc);
    w_ctr(ppb, 0xd);

    /*
     * ACK should drop low while SELIN is deasserted.
     * FAULT should drop low when the SCSI device latches the bus.
     */
    k = IMM_SELECT_TMO;
    do {
        k--;
    }
    while (!(r_str(ppb) & 0x08) && (k));

    /*
     * Place the interface back into a sane state (status mode)
     */
    w_ctr(ppb, 0xc);
    return (k) ? 1 : 0;
}

static int imm_init(imm_struct *dev)
{
    if (imm_connect(dev, 0) != 1)
        return -EIO;
    imm_reset_pulse(dev->base);
    mdelay(1);  /* Delay to allow devices to settle */
    imm_disconnect(dev);
    mdelay(1);  /* Another delay to allow devices to settle */
    return device_check(dev);
}

static inline int imm_send_command(struct scsi_cmnd *cmd)
{
    imm_struct *dev = imm_dev(cmd->device->host);
    int k;

    /* NOTE: IMM uses byte pairs */
    for (k = 0; k < cmd->cmd_len; k += 2)
        if (!imm_out(dev, &cmd->cmnd[k], 2))
            return 0;
    return 1;
}

/*
 * The bulk flag enables some optimisations in the data transfer loops,
 * it should be true for any command that transfers data in integral
 * numbers of sectors.
 * 
 * The driver appears to remain stable if we speed up the parallel port
 * i/o in this function, but not elsewhere.
 */
static int imm_completion(struct scsi_cmnd *cmd)
{
    /* Return codes:
     * -1     Error
     *  0     Told to schedule
     *  1     Finished data transfer
     */
    imm_struct *dev = imm_dev(cmd->device->host);
    unsigned short ppb = dev->base;
    unsigned long start_jiffies = jiffies;

    unsigned char r, v;
    int fast, bulk, status;

    v = cmd->cmnd[0];
    bulk = ((v == READ_6) ||
        (v == READ_10) || (v == WRITE_6) || (v == WRITE_10));

    /*
     * We only get here if the drive is ready to comunicate,
     * hence no need for a full imm_wait.
     */
    w_ctr(ppb, 0x0c);
    r = (r_str(ppb) & 0xb8);

    /*
     * while (device is not ready to send status byte)
     *     loop;
     */
    while (r != (unsigned char) 0xb8) {
        /*
         * If we have been running for more than a full timer tick
         * then take a rest.
         */
        if (time_after(jiffies, start_jiffies + 1))
            return 0;

        /*
         * FAIL if:
         * a) Drive status is screwy (!ready && !present)
         * b) Drive is requesting/sending more data than expected
         */
        if (((r & 0x88) != 0x88) || (cmd->SCp.this_residual <= 0)) {
            imm_fail(dev, DID_ERROR);
            return -1;  /* ERROR_RETURN */
        }
        /* determine if we should use burst I/O */
        if (dev->rd == 0) {
            fast = (bulk
                && (cmd->SCp.this_residual >=
                    IMM_BURST_SIZE)) ? IMM_BURST_SIZE : 2;
            status = imm_out(dev, cmd->SCp.ptr, fast);
        } else {
            fast = (bulk
                && (cmd->SCp.this_residual >=
                    IMM_BURST_SIZE)) ? IMM_BURST_SIZE : 1;
            status = imm_in(dev, cmd->SCp.ptr, fast);
        }

        cmd->SCp.ptr += fast;
        cmd->SCp.this_residual -= fast;

        if (!status) {
            imm_fail(dev, DID_BUS_BUSY);
            return -1;  /* ERROR_RETURN */
        }
        if (cmd->SCp.buffer && !cmd->SCp.this_residual) {
            /* if scatter/gather, advance to the next segment */
            if (cmd->SCp.buffers_residual--) {
                cmd->SCp.buffer++;
                cmd->SCp.this_residual =
                    cmd->SCp.buffer->length;
                cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);

                /*
                 * Make sure that we transfer even number of bytes
                 * otherwise it makes imm_byte_out() messy.
                 */
                if (cmd->SCp.this_residual & 0x01)
                    cmd->SCp.this_residual++;
            }
        }
        /* Now check to see if the drive is ready to comunicate */
        w_ctr(ppb, 0x0c);
        r = (r_str(ppb) & 0xb8);

        /* If not, drop back down to the scheduler and wait a timer tick */
        if (!(r & 0x80))
            return 0;
    }
    return 1;       /* FINISH_RETURN */
}

/*
 * Since the IMM itself doesn't generate interrupts, we use
 * the scheduler's task queue to generate a stream of call-backs and
 * complete the request when the drive is ready.
 */
static void imm_interrupt(struct work_struct *work)
{
    imm_struct *dev = container_of(work, imm_struct, imm_tq.work);
    struct scsi_cmnd *cmd = dev->cur_cmd;
    struct Scsi_Host *host = cmd->device->host;
    unsigned long flags;

    if (imm_engine(dev, cmd)) {
        schedule_delayed_work(&dev->imm_tq, 1);
        return;
    }
    /* Command must of completed hence it is safe to let go... */
#if IMM_DEBUG > 0
    switch ((cmd->result >> 16) & 0xff) {
    case DID_OK:
        break;
    case DID_NO_CONNECT:
        printk("imm: no device at SCSI ID %i\n", cmd->device->id);
        break;
    case DID_BUS_BUSY:
        printk("imm: BUS BUSY - EPP timeout detected\n");
        break;
    case DID_TIME_OUT:
        printk("imm: unknown timeout\n");
        break;
    case DID_ABORT:
        printk("imm: told to abort\n");
        break;
    case DID_PARITY:
        printk("imm: parity error (???)\n");
        break;
    case DID_ERROR:
        printk("imm: internal driver error\n");
        break;
    case DID_RESET:
        printk("imm: told to reset device\n");
        break;
    case DID_BAD_INTR:
        printk("imm: bad interrupt (???)\n");
        break;
    default:
        printk("imm: bad return code (%02x)\n",
               (cmd->result >> 16) & 0xff);
    }
#endif

    if (cmd->SCp.phase > 1)
        imm_disconnect(dev);

    imm_pb_dismiss(dev);

    spin_lock_irqsave(host->host_lock, flags);
    dev->cur_cmd = NULL;
    cmd->scsi_done(cmd);
    spin_unlock_irqrestore(host->host_lock, flags);
    return;
}

static int imm_engine(imm_struct *dev, struct scsi_cmnd *cmd)
{
    unsigned short ppb = dev->base;
    unsigned char l = 0, h = 0;
    int retv, x;

    /* First check for any errors that may have occurred
     * Here we check for internal errors
     */
    if (dev->failed)
        return 0;

    switch (cmd->SCp.phase) {
    case 0:     /* Phase 0 - Waiting for parport */
        if (time_after(jiffies, dev->jstart + HZ)) {
            /*
             * We waited more than a second
             * for parport to call us
             */
            imm_fail(dev, DID_BUS_BUSY);
            return 0;
        }
        return 1;   /* wait until imm_wakeup claims parport */
        /* Phase 1 - Connected */
    case 1:
        imm_connect(dev, CONNECT_EPP_MAYBE);
        cmd->SCp.phase++;

        /* Phase 2 - We are now talking to the scsi bus */
    case 2:
        if (!imm_select(dev, scmd_id(cmd))) {
            imm_fail(dev, DID_NO_CONNECT);
            return 0;
        }
        cmd->SCp.phase++;

        /* Phase 3 - Ready to accept a command */
    case 3:
        w_ctr(ppb, 0x0c);
        if (!(r_str(ppb) & 0x80))
            return 1;

        if (!imm_send_command(cmd))
            return 0;
        cmd->SCp.phase++;

        /* Phase 4 - Setup scatter/gather buffers */
    case 4:
        if (scsi_bufflen(cmd)) {
            cmd->SCp.buffer = scsi_sglist(cmd);
            cmd->SCp.this_residual = cmd->SCp.buffer->length;
            cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
        } else {
            cmd->SCp.buffer = NULL;
            cmd->SCp.this_residual = 0;
            cmd->SCp.ptr = NULL;
        }
        cmd->SCp.buffers_residual = scsi_sg_count(cmd) - 1;
        cmd->SCp.phase++;
        if (cmd->SCp.this_residual & 0x01)
            cmd->SCp.this_residual++;
        /* Phase 5 - Pre-Data transfer stage */
    case 5:
        /* Spin lock for BUSY */
        w_ctr(ppb, 0x0c);
        if (!(r_str(ppb) & 0x80))
            return 1;

        /* Require negotiation for read requests */
        x = (r_str(ppb) & 0xb8);
        dev->rd = (x & 0x10) ? 1 : 0;
        dev->dp = (x & 0x20) ? 0 : 1;

        if ((dev->dp) && (dev->rd))
            if (imm_negotiate(dev))
                return 0;
        cmd->SCp.phase++;

        /* Phase 6 - Data transfer stage */
    case 6:
        /* Spin lock for BUSY */
        w_ctr(ppb, 0x0c);
        if (!(r_str(ppb) & 0x80))
            return 1;

        if (dev->dp) {
            retv = imm_completion(cmd);
            if (retv == -1)
                return 0;
            if (retv == 0)
                return 1;
        }
        cmd->SCp.phase++;

        /* Phase 7 - Post data transfer stage */
    case 7:
        if ((dev->dp) && (dev->rd)) {
            if ((dev->mode == IMM_NIBBLE) || (dev->mode == IMM_PS2)) {
                w_ctr(ppb, 0x4);
                w_ctr(ppb, 0xc);
                w_ctr(ppb, 0xe);
                w_ctr(ppb, 0x4);
            }
        }
        cmd->SCp.phase++;

        /* Phase 8 - Read status/message */
    case 8:
        /* Check for data overrun */
        if (imm_wait(dev) != (unsigned char) 0xb8) {
            imm_fail(dev, DID_ERROR);
            return 0;
        }
        if (imm_negotiate(dev))
            return 0;
        if (imm_in(dev, &l, 1)) {   /* read status byte */
            /* Check for optional message byte */
            if (imm_wait(dev) == (unsigned char) 0xb8)
                imm_in(dev, &h, 1);
            cmd->result = (DID_OK << 16) + (l & STATUS_MASK);
        }
        if ((dev->mode == IMM_NIBBLE) || (dev->mode == IMM_PS2)) {
            w_ctr(ppb, 0x4);
            w_ctr(ppb, 0xc);
            w_ctr(ppb, 0xe);
            w_ctr(ppb, 0x4);
        }
        return 0;   /* Finished */
        break;

    default:
        printk("imm: Invalid scsi phase\n");
    }
    return 0;
}

static int imm_queuecommand_lck(struct scsi_cmnd *cmd,
        void (*done)(struct scsi_cmnd *))
{
    imm_struct *dev = imm_dev(cmd->device->host);

    if (dev->cur_cmd) {
        printk("IMM: bug in imm_queuecommand\n");
        return 0;
    }
    dev->failed = 0;
    dev->jstart = jiffies;
    dev->cur_cmd = cmd;
    cmd->scsi_done = done;
    cmd->result = DID_ERROR << 16;  /* default return code */
    cmd->SCp.phase = 0; /* bus free */

    schedule_delayed_work(&dev->imm_tq, 0);

    imm_pb_claim(dev);

    return 0;
}

static DEF_SCSI_QCMD(imm_queuecommand)

/*
 * Apparently the disk->capacity attribute is off by 1 sector 
 * for all disk drives.  We add the one here, but it should really
 * be done in sd.c.  Even if it gets fixed there, this will still
 * work.
 */
static int imm_biosparam(struct scsi_device *sdev, struct block_device *dev,
             sector_t capacity, int ip[])
{
    ip[0] = 0x40;
    ip[1] = 0x20;
    ip[2] = ((unsigned long) capacity + 1) / (ip[0] * ip[1]);
    if (ip[2] > 1024) {
        ip[0] = 0xff;
        ip[1] = 0x3f;
        ip[2] = ((unsigned long) capacity + 1) / (ip[0] * ip[1]);
    }
    return 0;
}

static int imm_abort(struct scsi_cmnd *cmd)
{
    imm_struct *dev = imm_dev(cmd->device->host);
    /*
     * There is no method for aborting commands since Iomega
     * have tied the SCSI_MESSAGE line high in the interface
     */

    switch (cmd->SCp.phase) {
    case 0:     /* Do not have access to parport */
    case 1:     /* Have not connected to interface */
        dev->cur_cmd = NULL;    /* Forget the problem */
        return SUCCESS;
        break;
    default:        /* SCSI command sent, can not abort */
        return FAILED;
        break;
    }
}

static void imm_reset_pulse(unsigned int base)
{
    w_ctr(base, 0x04);
    w_dtr(base, 0x40);
    udelay(1);
    w_ctr(base, 0x0c);
    w_ctr(base, 0x0d);
    udelay(50);
    w_ctr(base, 0x0c);
    w_ctr(base, 0x04);
}

static int imm_reset(struct scsi_cmnd *cmd)
{
    imm_struct *dev = imm_dev(cmd->device->host);

    if (cmd->SCp.phase)
        imm_disconnect(dev);
    dev->cur_cmd = NULL;    /* Forget the problem */

    imm_connect(dev, CONNECT_NORMAL);
    imm_reset_pulse(dev->base);
    mdelay(1);      /* device settle delay */
    imm_disconnect(dev);
    mdelay(1);      /* device settle delay */
    return SUCCESS;
}

static int device_check(imm_struct *dev)
{
    /* This routine looks for a device and then attempts to use EPP
       to send a command. If all goes as planned then EPP is available. */

    static char cmd[6] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
    int loop, old_mode, status, k, ppb = dev->base;
    unsigned char l;

    old_mode = dev->mode;
    for (loop = 0; loop < 8; loop++) {
        /* Attempt to use EPP for Test Unit Ready */
        if ((ppb & 0x0007) == 0x0000)
            dev->mode = IMM_EPP_32;

          second_pass:
        imm_connect(dev, CONNECT_EPP_MAYBE);
        /* Select SCSI device */
        if (!imm_select(dev, loop)) {
            imm_disconnect(dev);
            continue;
        }
        printk("imm: Found device at ID %i, Attempting to use %s\n",
               loop, IMM_MODE_STRING[dev->mode]);

        /* Send SCSI command */
        status = 1;
        w_ctr(ppb, 0x0c);
        for (l = 0; (l < 3) && (status); l++)
            status = imm_out(dev, &cmd[l << 1], 2);

        if (!status) {
            imm_disconnect(dev);
            imm_connect(dev, CONNECT_EPP_MAYBE);
            imm_reset_pulse(dev->base);
            udelay(1000);
            imm_disconnect(dev);
            udelay(1000);
            if (dev->mode == IMM_EPP_32) {
                dev->mode = old_mode;
                goto second_pass;
            }
            printk("imm: Unable to establish communication\n");
            return -EIO;
        }
        w_ctr(ppb, 0x0c);

        k = 1000000;    /* 1 Second */
        do {
            l = r_str(ppb);
            k--;
            udelay(1);
        } while (!(l & 0x80) && (k));

        l &= 0xb8;

        if (l != 0xb8) {
            imm_disconnect(dev);
            imm_connect(dev, CONNECT_EPP_MAYBE);
            imm_reset_pulse(dev->base);
            udelay(1000);
            imm_disconnect(dev);
            udelay(1000);
            if (dev->mode == IMM_EPP_32) {
                dev->mode = old_mode;
                goto second_pass;
            }
            printk
                ("imm: Unable to establish communication\n");
            return -EIO;
        }
        imm_disconnect(dev);
        printk
            ("imm: Communication established at 0x%x with ID %i using %s\n",
             ppb, loop, IMM_MODE_STRING[dev->mode]);
        imm_connect(dev, CONNECT_EPP_MAYBE);
        imm_reset_pulse(dev->base);
        udelay(1000);
        imm_disconnect(dev);
        udelay(1000);
        return 0;
    }
    printk("imm: No devices found\n");
    return -ENODEV;
}

/*
 * imm cannot deal with highmem, so this causes all IO pages for this host
 * to reside in low memory (hence mapped)
 */
static int imm_adjust_queue(struct scsi_device *device)
{
    blk_queue_bounce_limit(device->request_queue, BLK_BOUNCE_HIGH);
    return 0;
}

static struct scsi_host_template imm_template = {
    .module         = THIS_MODULE,
    .proc_name      = "imm",
    .proc_info      = imm_proc_info,
    .name           = "Iomega VPI2 (imm) interface",
    .queuecommand       = imm_queuecommand,
    .eh_abort_handler   = imm_abort,
    .eh_bus_reset_handler   = imm_reset,
    .eh_host_reset_handler  = imm_reset,
    .bios_param     = imm_biosparam,
    .this_id        = 7,
    .sg_tablesize       = SG_ALL,
    .cmd_per_lun        = 1,
    .use_clustering     = ENABLE_CLUSTERING,
    .can_queue      = 1,
    .slave_alloc        = imm_adjust_queue,
};

/***************************************************************************
 *                   Parallel port probing routines                        *
 ***************************************************************************/

static LIST_HEAD(imm_hosts);

static int __imm_attach(struct parport *pb)
{
    struct Scsi_Host *host;
    imm_struct *dev;
    DECLARE_WAIT_QUEUE_HEAD_ONSTACK(waiting);
    DEFINE_WAIT(wait);
    int ports;
    int modes, ppb;
    int err = -ENOMEM;

    init_waitqueue_head(&waiting);

    dev = kzalloc(sizeof(imm_struct), GFP_KERNEL);
    if (!dev)
        return -ENOMEM;


    dev->base = -1;
    dev->mode = IMM_AUTODETECT;
    INIT_LIST_HEAD(&dev->list);

    dev->dev = parport_register_device(pb, "imm", NULL, imm_wakeup,
                        NULL, 0, dev);

    if (!dev->dev)
        goto out;


    /* Claim the bus so it remembers what we do to the control
     * registers. [ CTR and ECP ]
     */
    err = -EBUSY;
    dev->waiting = &waiting;
    prepare_to_wait(&waiting, &wait, TASK_UNINTERRUPTIBLE);
    if (imm_pb_claim(dev))
        schedule_timeout(3 * HZ);
    if (dev->wanted) {
        printk(KERN_ERR "imm%d: failed to claim parport because "
            "a pardevice is owning the port for too long "
            "time!\n", pb->number);
        imm_pb_dismiss(dev);
        dev->waiting = NULL;
        finish_wait(&waiting, &wait);
        goto out1;
    }
    dev->waiting = NULL;
    finish_wait(&waiting, &wait);
    ppb = dev->base = dev->dev->port->base;
    dev->base_hi = dev->dev->port->base_hi;
    w_ctr(ppb, 0x0c);
    modes = dev->dev->port->modes;

    /* Mode detection works up the chain of speed
     * This avoids a nasty if-then-else-if-... tree
     */
    dev->mode = IMM_NIBBLE;

    if (modes & PARPORT_MODE_TRISTATE)
        dev->mode = IMM_PS2;

    /* Done configuration */

    err = imm_init(dev);

    imm_pb_release(dev);

    if (err)
        goto out1;

    /* now the glue ... */
    if (dev->mode == IMM_NIBBLE || dev->mode == IMM_PS2)
        ports = 3;
    else
        ports = 8;

    INIT_DELAYED_WORK(&dev->imm_tq, imm_interrupt);

    err = -ENOMEM;
    host = scsi_host_alloc(&imm_template, sizeof(imm_struct *));
    if (!host)
        goto out1;
    host->io_port = pb->base;
    host->n_io_port = ports;
    host->dma_channel = -1;
    host->unique_id = pb->number;
    *(imm_struct **)&host->hostdata = dev;
    dev->host = host;
    list_add_tail(&dev->list, &imm_hosts);
    err = scsi_add_host(host, NULL);
    if (err)
        goto out2;
    scsi_scan_host(host);
    return 0;

out2:
    list_del_init(&dev->list);
    scsi_host_put(host);
out1:
    parport_unregister_device(dev->dev);
out:
    kfree(dev);
    return err;
}

static void imm_attach(struct parport *pb)
{
    __imm_attach(pb);
}

static void imm_detach(struct parport *pb)
{
    imm_struct *dev;
    list_for_each_entry(dev, &imm_hosts, list) {
        if (dev->dev->port == pb) {
            list_del_init(&dev->list);
            scsi_remove_host(dev->host);
            scsi_host_put(dev->host);
            parport_unregister_device(dev->dev);
            kfree(dev);
            break;
        }
    }
}

static struct parport_driver imm_driver = {
    .name   = "imm",
    .attach = imm_attach,
    .detach = imm_detach,
};

static int __init imm_driver_init(void)
{
    printk("imm: Version %s\n", IMM_VERSION);
    return parport_register_driver(&imm_driver);
}

static void __exit imm_driver_exit(void)
{
    parport_unregister_driver(&imm_driver);
}

module_init(imm_driver_init);
module_exit(imm_driver_exit);

MODULE_LICENSE("GPL");