Import 2.3.18pre1

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

/* 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.)
 * 
 * Current Maintainer: David Campbell (Perth, Western Australia)
 *                     campbell@torque.net
 *
 * My unoffical company acronym list is 21 pages long:
 *      FLA:    Four letter acronym with built in facility for
 *              future expansion to five letters.
 */

#include <linux/config.h>

/* The following #define is to avoid a clash with hosts.c */
#define IMM_CODE 1
#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

void imm_reset_pulse(unsigned int base);
static int device_check(int host_no);

#include <linux/blk.h>
#include <asm/io.h>
#include <linux/parport.h>
#include "sd.h"
#include "hosts.h"
typedef struct {
    struct pardevice *dev;      /* Parport device entry         */
    int base;                   /* Actual port address          */
    int mode;                   /* Transfer mode                */
    int host;                   /* Host number (for proc)       */
    Scsi_Cmnd *cur_cmd;         /* Current queued command       */
    struct tq_struct imm_tq;    /* Polling interupt 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 p_busy:1;          /* Parport sharing busy flag    */
} imm_struct;

#define IMM_EMPTY \
{       dev:            NULL,           \
        base:           -1,             \
        mode:           IMM_AUTODETECT, \
        host:           -1,             \
        cur_cmd:        NULL,           \
        imm_tq:         {0, 0, imm_interrupt, NULL},    \
        jstart:         0,              \
        failed:         0,              \
        dp:             0,              \
        rd:             0,              \
        p_busy:         0               \
}

#include "imm.h"
#define NO_HOSTS 4
static imm_struct imm_hosts[NO_HOSTS] =
{IMM_EMPTY, IMM_EMPTY, IMM_EMPTY, IMM_EMPTY};

#define IMM_BASE(x)     imm_hosts[(x)].base

int parbus_base[NO_HOSTS] =
{0x03bc, 0x0378, 0x0278, 0x0000};

void imm_wakeup(void *ref)
{
    imm_struct *imm_dev = (imm_struct *) ref;

    if (!imm_dev->p_busy)
        return;

    if (parport_claim(imm_dev->dev)) {
        printk("imm: bug in imm_wakeup\n");
        return;
    }
    imm_dev->p_busy = 0;
    imm_dev->base = imm_dev->dev->port->base;
    if (imm_dev->cur_cmd)
        imm_dev->cur_cmd->SCp.phase++;
    return;
}

int imm_release(struct Scsi_Host *host)
{
    int host_no = host->unique_id;

    printk("Releasing imm%i\n", host_no);
    parport_unregister_device(imm_hosts[host_no].dev);
    return 0;
}

static int imm_pb_claim(int host_no)
{
    if (parport_claim(imm_hosts[host_no].dev)) {
        imm_hosts[host_no].p_busy = 1;
        return 1;
    }
    if (imm_hosts[host_no].cur_cmd)
        imm_hosts[host_no].cur_cmd->SCp.phase++;
    return 0;
}

#define imm_pb_release(x) parport_release(imm_hosts[(x)].dev)

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

#ifdef MODULE
Scsi_Host_Template driver_template = IMM;
#include  "scsi_module.c"
#endif

int imm_detect(Scsi_Host_Template * host)
{
    struct Scsi_Host *hreg;
    int ports;
    int i, nhosts, try_again;
    struct parport *pb = parport_enumerate();

    printk("imm: Version %s\n", IMM_VERSION);
    nhosts = 0;
    try_again = 0;

    if (!pb) {
        printk("imm: parport reports no devices.\n");
        return 0;
    }
  retry_entry:
    for (i = 0; pb; i++, pb = pb->next) {
        int modes, ppb;

        imm_hosts[i].dev =
            parport_register_device(pb, "imm", NULL, imm_wakeup,
                                    NULL, 0, (void *) &imm_hosts[i]);

        if (!imm_hosts[i].dev)
            continue;

        /* Claim the bus so it remembers what we do to the control
         * registers. [ CTR and ECP ]
         */
        if (imm_pb_claim(i)) {
            unsigned long now = jiffies;
            while (imm_hosts[i].p_busy) {
                schedule();     /* We are safe to schedule here */
                if (time_after(jiffies, now + 3 * HZ)) {
                    printk(KERN_ERR "imm%d: failed to claim parport because a "
                      "pardevice is owning the port for too longtime!\n",
                           i);
                    return 0;
                }
            }
        }
        ppb = IMM_BASE(i) = imm_hosts[i].dev->port->base;
        w_ctr(ppb, 0x0c);
        modes = imm_hosts[i].dev->port->modes;

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

        if (modes & PARPORT_MODE_PCPS2)
            imm_hosts[i].mode = IMM_PS2;

        if (modes & PARPORT_MODE_PCECPPS2) {
            w_ecr(ppb, 0x20);
            imm_hosts[i].mode = IMM_PS2;
        }
        if (modes & PARPORT_MODE_PCECPEPP)
            w_ecr(ppb, 0x80);

        /* Done configuration */
        imm_pb_release(i);

        if (imm_init(i)) {
            parport_unregister_device(imm_hosts[i].dev);
            continue;
        }
        /* now the glue ... */
        switch (imm_hosts[i].mode) {
        case IMM_NIBBLE:
            ports = 3;
            break;
        case IMM_PS2:
            ports = 3;
            break;
        case IMM_EPP_8:
        case IMM_EPP_16:
        case IMM_EPP_32:
            ports = 8;
            break;
        default:                /* Never gets here */
            continue;
        }

        host->can_queue = IMM_CAN_QUEUE;
        host->sg_tablesize = imm_sg;
        hreg = scsi_register(host, 0);
        hreg->io_port = pb->base;
        hreg->n_io_port = ports;
        hreg->dma_channel = -1;
        hreg->unique_id = i;
        imm_hosts[i].host = hreg->host_no;
        nhosts++;
    }
    if (nhosts == 0) {
        if (try_again == 1)
            return 0;
        try_again = 1;
        goto retry_entry;
    } else
        return 1;               /* return number of hosts detected */
}

/* 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... (To 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(int hostno, char *buffer, int length)
{
    unsigned long x;

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

int imm_proc_info(char *buffer, char **start, off_t offset,
                  int length, int hostno, int inout)
{
    int i;
    int len = 0;

    for (i = 0; i < 4; i++)
        if (imm_hosts[i].host == hostno)
            break;

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

    len += sprintf(buffer + len, "Version : %s\n", IMM_VERSION);
    len += sprintf(buffer + len, "Parport : %s\n", imm_hosts[i].dev->port->name);
    len += sprintf(buffer + len, "Mode    : %s\n", IMM_MODE_STRING[imm_hosts[i].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, __FUNCTION__, __LINE__); imm_fail_func(x,y);
static inline void imm_fail_func(int host_no, int error_code)
#else
static inline void imm_fail(int host_no, int error_code)
#endif
{
    /* If we fail a device then we trash status / message bytes */
    if (imm_hosts[host_no].cur_cmd) {
        imm_hosts[host_no].cur_cmd->result = error_code << 16;
        imm_hosts[host_no].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(int host_no)
{
    int k;
    unsigned short ppb = IMM_BASE(host_no);
    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(host_no, 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 1248-1994 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->host, DID_ERROR);
    }
    return a;
}

static inline void epp_reset(unsigned short ppb)
{
    int i;

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

static inline void ecp_sync(unsigned short ppb)
{
    int i;

    if ((r_ecr(ppb) & 0xe0) != 0x80)
        return;

    for (i = 0; i < 100; i++) {
        if (r_ecr(ppb) & 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(int host_no, char *buffer, int len)
{
    int r;
    unsigned short ppb = IMM_BASE(host_no);

    r = imm_wait(host_no);

    /*
     * Make sure that:
     * a) the SCSI bus is BUSY (device still listening)
     * b) the device is listening
     */
    if ((r & 0x18) != 0x08) {
        imm_fail(host_no, DID_ERROR);
        printk("IMM: returned SCSI status %2x\n", r);
        return 0;
    }
    switch (imm_hosts[host_no].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(ppb);
        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(int host_no, char *buffer, int len)
{
    int r;
    unsigned short ppb = IMM_BASE(host_no);

    r = imm_wait(host_no);

    /*
     * Make sure that:
     * a) the SCSI bus is BUSY (device still listening)
     * b) the device is sending data
     */
    if ((r & 0x18) != 0x18) {
        imm_fail(host_no, DID_ERROR);
        return 0;
    }
    switch (imm_hosts[host_no].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(ppb);
        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(int host_no, int flag)
{
    unsigned short ppb = IMM_BASE(host_no);

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

    if ((imm_hosts[host_no].mode == IMM_EPP_8) ||
        (imm_hosts[host_no].mode == IMM_EPP_16) ||
        (imm_hosts[host_no].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(int host_no)
{
    unsigned short ppb = IMM_BASE(host_no);

    imm_cpp(ppb, 0x30);         /* Disconnect all devices */
}

static int imm_select(int host_no, int target)
{
    int k;
    unsigned short ppb = IMM_BASE(host_no);

    /*
     * 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(int host_no)
{
    int retv;

#if defined(CONFIG_PARPORT) || defined(CONFIG_PARPORT_MODULE)
    if (imm_pb_claim(host_no))
        while (imm_hosts[host_no].p_busy)
            schedule();         /* We can safe schedule here */
#endif
    retv = imm_connect(host_no, 0);

    if (retv == 1) {
        imm_reset_pulse(IMM_BASE(host_no));
        udelay(1000);           /* Delay to allow devices to settle */
        imm_disconnect(host_no);
        udelay(1000);           /* Another delay to allow devices to settle */
        retv = device_check(host_no);
        imm_pb_release(host_no);
        return retv;
    }
    imm_pb_release(host_no);
    return 1;
}

static inline int imm_send_command(Scsi_Cmnd * cmd)
{
    int host_no = cmd->host->unique_id;
    int k;

    /* NOTE: IMM uses byte pairs */
    for (k = 0; k < cmd->cmd_len; k += 2)
        if (!imm_out(host_no, &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(Scsi_Cmnd * cmd)
{
    /* Return codes:
     * -1     Error
     *  0     Told to schedule
     *  1     Finished data transfer
     */
    int host_no = cmd->host->unique_id;
    unsigned short ppb = IMM_BASE(host_no);
    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(host_no, DID_ERROR);
            return -1;          /* ERROR_RETURN */
        }
        /* determine if we should use burst I/O */
        if (imm_hosts[host_no].rd == 0) {
            fast = (bulk && (cmd->SCp.this_residual >= IMM_BURST_SIZE)) ? IMM_BURST_SIZE : 2;
            status = imm_out(host_no, cmd->SCp.ptr, fast);
        } else {
            fast = (bulk && (cmd->SCp.this_residual >= IMM_BURST_SIZE)) ? IMM_BURST_SIZE : 1;
            status = imm_in(host_no, cmd->SCp.ptr, fast);
        }

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

        if (!status) {
            imm_fail(host_no, 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 = cmd->SCp.buffer->address;

                /*
                 * 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++;
                    printk("IMM: adjusted buffer for 16 bit transfer\n");
                }
            }
        }
        /* 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 */
}

/* deprecated synchronous interface */
int imm_command(Scsi_Cmnd * cmd)
{
    static int first_pass = 1;
    int host_no = cmd->host->unique_id;

    if (first_pass) {
        printk("imm: using non-queuing interface\n");
        first_pass = 0;
    }
    if (imm_hosts[host_no].cur_cmd) {
        printk("IMM: bug in imm_command\n");
        return 0;
    }
    imm_hosts[host_no].failed = 0;
    imm_hosts[host_no].jstart = jiffies;
    imm_hosts[host_no].cur_cmd = cmd;
    cmd->result = DID_ERROR << 16;      /* default return code */
    cmd->SCp.phase = 0;

    imm_pb_claim(host_no);

    while (imm_engine(&imm_hosts[host_no], cmd))
        schedule();

    if (cmd->SCp.phase)         /* Only disconnect if we have connected */
        imm_disconnect(cmd->host->unique_id);

    imm_pb_release(host_no);
    imm_hosts[host_no].cur_cmd = 0;
    return cmd->result;
}

/*
 * 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(void *data)
{
    imm_struct *tmp = (imm_struct *) data;
    Scsi_Cmnd *cmd = tmp->cur_cmd;
    unsigned long flags;

    if (!cmd) {
        printk("IMM: bug in imm_interrupt\n");
        return;
    }
    if (imm_engine(tmp, cmd)) {
        tmp->imm_tq.data = (void *) tmp;
        tmp->imm_tq.sync = 0;
        queue_task(&tmp->imm_tq, &tq_timer);
        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->target);
        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(cmd->host->unique_id);
    if (cmd->SCp.phase > 0)
        imm_pb_release(cmd->host->unique_id);

    spin_lock_irqsave(&io_request_lock, flags);
    tmp->cur_cmd = 0;
    cmd->scsi_done(cmd);
    spin_unlock_irqrestore(&io_request_lock, flags);
    return;
}

static int imm_engine(imm_struct * tmp, Scsi_Cmnd * cmd)
{
    int host_no = cmd->host->unique_id;
    unsigned short ppb = IMM_BASE(host_no);
    unsigned char l = 0, h = 0;
    int retv, x;

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

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

        /* Phase 2 - We are now talking to the scsi bus */
    case 2:
        if (!imm_select(host_no, cmd->target)) {
            imm_fail(host_no, 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 (cmd->use_sg) {
            /* if many buffers are available, start filling the first */
            cmd->SCp.buffer = (struct scatterlist *) cmd->request_buffer;
            cmd->SCp.this_residual = cmd->SCp.buffer->length;
            cmd->SCp.ptr = cmd->SCp.buffer->address;
        } else {
            /* else fill the only available buffer */
            cmd->SCp.buffer = NULL;
            cmd->SCp.this_residual = cmd->request_bufflen;
            cmd->SCp.ptr = cmd->request_buffer;
        }
        cmd->SCp.buffers_residual = cmd->use_sg;
        cmd->SCp.phase++;
        if (cmd->SCp.this_residual & 0x01) {
            cmd->SCp.this_residual++;
            printk("IMM: adjusted buffer for 16 bit transfer\n");
        }
        /* 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);
        tmp->rd = (x & 0x10) ? 1 : 0;
        tmp->dp = (x & 0x20) ? 0 : 1;

        if ((tmp->dp) && (tmp->rd))
            if (imm_negotiate(tmp))
                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 (tmp->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 ((tmp->dp) && (tmp->rd)) {
            if ((tmp->mode == IMM_NIBBLE) || (tmp->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(host_no) != (unsigned char) 0xb8) {
            imm_fail(host_no, DID_ERROR);
            return 0;
        }
        if (imm_negotiate(tmp))
            return 0;
        if (imm_in(host_no, &l, 1)) {   /* read status byte */
            /* Check for optional message byte */
            if (imm_wait(host_no) == (unsigned char) 0xb8)
                imm_in(host_no, &h, 1);
            cmd->result = (DID_OK << 16) + (l & STATUS_MASK);
        }
        if ((tmp->mode == IMM_NIBBLE) || (tmp->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;
}

int imm_queuecommand(Scsi_Cmnd * cmd, void (*done) (Scsi_Cmnd *))
{
    int host_no = cmd->host->unique_id;

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

    imm_pb_claim(host_no);

    imm_hosts[host_no].imm_tq.data = imm_hosts + host_no;
    imm_hosts[host_no].imm_tq.sync = 0;
    queue_task(&imm_hosts[host_no].imm_tq, &tq_immediate);
    mark_bh(IMMEDIATE_BH);

    return 0;
}

/*
 * Aimmrently the 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.
 */
int imm_biosparam(Disk * disk, kdev_t dev, int ip[])
{
    ip[0] = 0x40;
    ip[1] = 0x20;
    ip[2] = (disk->capacity + 1) / (ip[0] * ip[1]);
    if (ip[2] > 1024) {
        ip[0] = 0xff;
        ip[1] = 0x3f;
        ip[2] = (disk->capacity + 1) / (ip[0] * ip[1]);
        if (ip[2] > 1023)
            ip[2] = 1023;
    }
    return 0;
}

int imm_abort(Scsi_Cmnd * cmd)
{
    int host_no = cmd->host->unique_id;
    /*
     * 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 */
        imm_hosts[host_no].cur_cmd = NULL;      /* Forget the problem */
        return SUCCESS;
        break;
    default:                    /* SCSI command sent, can not abort */
        return FAILED;
        break;
    }
}

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);
}

int imm_reset(Scsi_Cmnd * cmd)
{
    int host_no = cmd->host->unique_id;

    if (cmd->SCp.phase)
        imm_disconnect(host_no);
    imm_hosts[host_no].cur_cmd = NULL;  /* Forget the problem */

    imm_connect(host_no, CONNECT_NORMAL);
    imm_reset_pulse(IMM_BASE(host_no));
    udelay(1000);               /* device settle delay */
    imm_disconnect(host_no);
    udelay(1000);               /* device settle delay */
    return SUCCESS;
}

static int device_check(int host_no)
{
    /* 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 = IMM_BASE(host_no);
    unsigned char l;

    old_mode = imm_hosts[host_no].mode;
    for (loop = 0; loop < 8; loop++) {
        /* Attempt to use EPP for Test Unit Ready */
        if ((ppb & 0x0007) == 0x0000)
            imm_hosts[host_no].mode = IMM_EPP_32;

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

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

        if (!status) {
            imm_disconnect(host_no);
            imm_connect(host_no, CONNECT_EPP_MAYBE);
            imm_reset_pulse(IMM_BASE(host_no));
            udelay(1000);
            imm_disconnect(host_no);
            udelay(1000);
            if (imm_hosts[host_no].mode == IMM_EPP_32) {
                imm_hosts[host_no].mode = old_mode;
                goto second_pass;
            }
            printk("imm: Unable to establish communication, aborting driver load.\n");
            return 1;
        }
        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(host_no);
            imm_connect(host_no, CONNECT_EPP_MAYBE);
            imm_reset_pulse(IMM_BASE(host_no));
            udelay(1000);
            imm_disconnect(host_no);
            udelay(1000);
            if (imm_hosts[host_no].mode == IMM_EPP_32) {
                imm_hosts[host_no].mode = old_mode;
                goto second_pass;
            }
            printk("imm: Unable to establish communication, aborting driver load.\n");
            return 1;
        }
        imm_disconnect(host_no);
        printk("imm: Communication established with ID %i using %s\n", loop,
               IMM_MODE_STRING[imm_hosts[host_no].mode]);
        imm_connect(host_no, CONNECT_EPP_MAYBE);
        imm_reset_pulse(IMM_BASE(host_no));
        udelay(1000);
        imm_disconnect(host_no);
        udelay(1000);
        return 0;
    }
    printk("imm: No devices found, aborting driver load.\n");
    return 1;
}