- Kai Germaschewski: ISDN update (including Makefiles)

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

/* ppa.c   --  low level driver for the IOMEGA PPA3 
 * parallel port SCSI host adapter.
 * 
 * (The PPA3 is the embedded controller in the ZIP drive.)
 * 
 * (c) 1995,1996 Grant R. Guenther, grant@torque.net,
 * under the terms of the GNU Public License.
 * 
 * Current Maintainer: David Campbell (Perth, Western Australia, GMT+0800)
 *                     campbell@torque.net
 */

#include <linux/config.h>

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

#include <linux/blk.h>
#include <asm/io.h>
#include <linux/parport.h>
#include "sd.h"
#include "hosts.h"
int ppa_release(struct Scsi_Host *);
static void ppa_reset_pulse(unsigned int base);

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 ppa_tq;    /* Polling interupt stuff       */
    unsigned long jstart;       /* Jiffies at start             */
    unsigned int failed:1;      /* Failure flag                 */
    unsigned int p_busy:1;      /* Parport sharing busy flag    */
} ppa_struct;

#define PPA_EMPTY       \
{       dev:            NULL,           \
        base:           -1,             \
        mode:           PPA_AUTODETECT, \
        host:           -1,             \
        cur_cmd:        NULL,           \
        ppa_tq:         { routine: ppa_interrupt },     \
        jstart:         0,              \
        failed:         0,              \
        p_busy:         0               \
}

#include  "ppa.h"

#define NO_HOSTS 4
static ppa_struct ppa_hosts[NO_HOSTS] =
{PPA_EMPTY, PPA_EMPTY, PPA_EMPTY, PPA_EMPTY};

#define PPA_BASE(x)     ppa_hosts[(x)].base

void ppa_wakeup(void *ref)
{
    ppa_struct *ppa_dev = (ppa_struct *) ref;

    if (!ppa_dev->p_busy)
        return;

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

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

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

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

#define ppa_pb_release(x) parport_release(ppa_hosts[(x)].dev)

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

static Scsi_Host_Template driver_template = PPA;
#include  "scsi_module.c"

/*
 * Start of Chipset kludges
 */

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

    /*
     * unlock to allow the lowlevel parport driver to probe
     * the irqs
     */
    spin_unlock_irq(&io_request_lock);
    pb = parport_enumerate();

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

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

        ppa_hosts[i].dev =
            parport_register_device(pb, "ppa", NULL, ppa_wakeup,
                                    NULL, 0, (void *) &ppa_hosts[i]);

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

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

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

        if (modes & PARPORT_MODE_TRISTATE)
            ppa_hosts[i].mode = PPA_PS2;

        if (modes & PARPORT_MODE_ECP) {
            w_ecr(ppb_hi, 0x20);
            ppa_hosts[i].mode = PPA_PS2;
        }
        if ((modes & PARPORT_MODE_EPP) && (modes & PARPORT_MODE_ECP))
            w_ecr(ppb_hi, 0x80);

        /* Done configuration */
        ppa_pb_release(i);

        if (ppa_init(i)) {
            parport_unregister_device(ppa_hosts[i].dev);
            continue;
        }
        /* now the glue ... */
        switch (ppa_hosts[i].mode) {
        case PPA_NIBBLE:
            ports = 3;
            break;
        case PPA_PS2:
            ports = 3;
            break;
        case PPA_EPP_8:
        case PPA_EPP_16:
        case PPA_EPP_32:
            ports = 8;
            break;
        default:                /* Never gets here */
            continue;
        }

        host->can_queue = PPA_CAN_QUEUE;
        host->sg_tablesize = ppa_sg;
        hreg = scsi_register(host, 0);
        if(hreg == NULL)
                continue;
        hreg->io_port = pb->base;
        hreg->n_io_port = ports;
        hreg->dma_channel = -1;
        hreg->unique_id = i;
        ppa_hosts[i].host = hreg->host_no;
        nhosts++;
    }
    if (nhosts == 0) {
        if (try_again == 1) {
            printk("WARNING - no ppa compatible devices found.\n");
            printk("  As of 31/Aug/1998 Iomega started shipping parallel\n");
            printk("  port ZIP drives with a different interface which is\n");
            printk("  supported by the imm (ZIP Plus) driver. If the\n");
            printk("  cable is marked with \"AutoDetect\", this is what has\n");
            printk("  happened.\n");
            return 0;
            spin_lock_irq(&io_request_lock);
        }
        try_again = 1;
        goto retry_entry;
    } else {
        spin_lock_irq(&io_request_lock);
        return 1;               /* return number of hosts detected */
    }
}

/* This is to give the ppa driver a way to modify the timings (and other
 * parameters) by writing to the /proc/scsi/ppa/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 ppa_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);
        ppa_hosts[hostno].mode = x;
        return length;
    }
    printk("ppa /proc: invalid variable\n");
    return (-EINVAL);
}

int ppa_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 (ppa_hosts[i].host == hostno)
            break;

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

    len += sprintf(buffer + len, "Version : %s\n", PPA_VERSION);
    len += sprintf(buffer + len, "Parport : %s\n", ppa_hosts[i].dev->port->name);
    len += sprintf(buffer + len, "Mode    : %s\n", PPA_MODE_STRING[ppa_hosts[i].mode]);

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

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

static int device_check(int host_no);

#if PPA_DEBUG > 0
#define ppa_fail(x,y) printk("ppa: ppa_fail(%i) from %s at line %d\n",\
           y, __FUNCTION__, __LINE__); ppa_fail_func(x,y);
static inline void ppa_fail_func(int host_no, int error_code)
#else
static inline void ppa_fail(int host_no, int error_code)
#endif
{
    /* If we fail a device then we trash status / message bytes */
    if (ppa_hosts[host_no].cur_cmd) {
        ppa_hosts[host_no].cur_cmd->result = error_code << 16;
        ppa_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 ppa_wait(int host_no)
{
    int k;
    unsigned short ppb = PPA_BASE(host_no);
    unsigned char r;

    k = PPA_SPIN_TMO;
    /* Wait for bit 6 and 7 - PJC */
    for (r = r_str (ppb); ((r & 0xc0)!=0xc0) && (k); k--) {
            udelay (1);
            r = r_str (ppb);
    }

    /*
     * return some status information.
     * Semantics: 0xc0 = ZIP wants more data
     *            0xd0 = ZIP wants to send more data
     *            0xe0 = ZIP is expecting SCSI command data
     *            0xf0 = end of transfer, ZIP is sending status
     */
    if (k)
        return (r & 0xf0);

    /* Counter expired - Time out occurred */
    ppa_fail(host_no, DID_TIME_OUT);
    printk("ppa timeout in ppa_wait\n");
    return 0;                   /* command timed out */
}

/*
 * 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(unsigned short hostno)
{
    int i, ppb_hi=ppa_hosts[hostno].dev->port->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("ppa: ECP sync failed as data still present in FIFO.\n");
    }
}

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

    for (i = len; i; i--) {
        w_dtr(base, *buffer++);
        w_ctr(base, 0xe);
        w_ctr(base, 0xc);
    }
    return 1;                   /* All went well - we hope! */
}

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

    for (i = len; i; i--) {
        *buffer++ = r_dtr(base);
        w_ctr(base, 0x27);
        w_ctr(base, 0x25);
    }
    return 1;                   /* All went well - we hope! */
}

static int ppa_nibble_in(unsigned short base, char *buffer, int len)
{
    for (; len; len--) {
        unsigned char h;

        w_ctr(base, 0x4);
        h = r_str(base) & 0xf0;
        w_ctr(base, 0x6);
        *buffer++ = h | ((r_str(base) & 0xf0) >> 4);
    }
    return 1;                   /* All went well - we hope! */
}

static int ppa_out(int host_no, char *buffer, int len)
{
    int r;
    unsigned short ppb = PPA_BASE(host_no);

    r = ppa_wait(host_no);

    if ((r & 0x50) != 0x40) {
        ppa_fail(host_no, DID_ERROR);
        return 0;
    }
    switch (ppa_hosts[host_no].mode) {
    case PPA_NIBBLE:
    case PPA_PS2:
        /* 8 bit output, with a loop */
        r = ppa_byte_out(ppb, buffer, len);
        break;

    case PPA_EPP_32:
    case PPA_EPP_16:
    case PPA_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(host_no);
        break;

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

static int ppa_in(int host_no, char *buffer, int len)
{
    int r;
    unsigned short ppb = PPA_BASE(host_no);

    r = ppa_wait(host_no);

    if ((r & 0x50) != 0x50) {
        ppa_fail(host_no, DID_ERROR);
        return 0;
    }
    switch (ppa_hosts[host_no].mode) {
    case PPA_NIBBLE:
        /* 4 bit input, with a loop */
        r = ppa_nibble_in(ppb, buffer, len);
        w_ctr(ppb, 0xc);
        break;

    case PPA_PS2:
        /* 8 bit input, with a loop */
        w_ctr(ppb, 0x25);
        r = ppa_byte_in(ppb, buffer, len);
        w_ctr(ppb, 0x4);
        w_ctr(ppb, 0xc);
        break;

    case PPA_EPP_32:
    case PPA_EPP_16:
    case PPA_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(host_no);
        break;

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

/* end of ppa_io.h */
static inline void ppa_d_pulse(unsigned short ppb, unsigned char b)
{
    w_dtr(ppb, b);
    w_ctr(ppb, 0xc);
    w_ctr(ppb, 0xe);
    w_ctr(ppb, 0xc);
    w_ctr(ppb, 0x4);
    w_ctr(ppb, 0xc);
}

static void ppa_disconnect(int host_no)
{
    unsigned short ppb = PPA_BASE(host_no);

    ppa_d_pulse(ppb, 0);
    ppa_d_pulse(ppb, 0x3c);
    ppa_d_pulse(ppb, 0x20);
    ppa_d_pulse(ppb, 0xf);
}

static inline void ppa_c_pulse(unsigned short ppb, unsigned char b)
{
    w_dtr(ppb, b);
    w_ctr(ppb, 0x4);
    w_ctr(ppb, 0x6);
    w_ctr(ppb, 0x4);
    w_ctr(ppb, 0xc);
}

static inline void ppa_connect(int host_no, int flag)
{
    unsigned short ppb = PPA_BASE(host_no);

    ppa_c_pulse(ppb, 0);
    ppa_c_pulse(ppb, 0x3c);
    ppa_c_pulse(ppb, 0x20);
    if ((flag == CONNECT_EPP_MAYBE) &&
        IN_EPP_MODE(ppa_hosts[host_no].mode))
        ppa_c_pulse(ppb, 0xcf);
    else
        ppa_c_pulse(ppb, 0x8f);
}

static int ppa_select(int host_no, int target)
{
    int k;
    unsigned short ppb = PPA_BASE(host_no);

    /*
     * Bit 6 (0x40) is the device selected bit.
     * First we must wait till the current device goes off line...
     */
    k = PPA_SELECT_TMO;
    do {
        k--;
    } while ((r_str(ppb) & 0x40) && (k));
    if (!k)
        return 0;

    w_dtr(ppb, (1 << target));
    w_ctr(ppb, 0xe);
    w_ctr(ppb, 0xc);
    w_dtr(ppb, 0x80);           /* This is NOT the initator */
    w_ctr(ppb, 0x8);

    k = PPA_SELECT_TMO;
    do {
        k--;
    }
    while (!(r_str(ppb) & 0x40) && (k));
    if (!k)
        return 0;

    return 1;
}

/* 
 * This is based on a trace of what the Iomega DOS 'guest' driver does.
 * I've tried several different kinds of parallel ports with guest and
 * coded this to react in the same ways that it does.
 * 
 * The return value from this function is just a hint about where the
 * handshaking failed.
 * 
 */
static int ppa_init(int host_no)
{
    int retv;
    unsigned short ppb = PPA_BASE(host_no);

#if defined(CONFIG_PARPORT) || defined(CONFIG_PARPORT_MODULE)
    if (ppa_pb_claim(host_no))
        while (ppa_hosts[host_no].p_busy)
            schedule();         /* We can safe schedule here */
#endif

    ppa_disconnect(host_no);
    ppa_connect(host_no, CONNECT_NORMAL);

    retv = 2;                   /* Failed */

    w_ctr(ppb, 0xe);
    if ((r_str(ppb) & 0x08) == 0x08)
        retv--;

    w_ctr(ppb, 0xc);
    if ((r_str(ppb) & 0x08) == 0x00)
        retv--;

    if (!retv)
        ppa_reset_pulse(ppb);
    udelay(1000);               /* Allow devices to settle down */
    ppa_disconnect(host_no);
    udelay(1000);               /* Another delay to allow devices to settle */

    if (!retv)
        retv = device_check(host_no);

    ppa_pb_release(host_no);
    return retv;
}

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

    w_ctr(PPA_BASE(host_no), 0x0c);

    for (k = 0; k < cmd->cmd_len; k++)
        if (!ppa_out(host_no, &cmd->cmnd[k], 1))
            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 ppa_completion(Scsi_Cmnd * cmd)
{
    /* Return codes:
     * -1     Error
     *  0     Told to schedule
     *  1     Finished data transfer
     */
    int host_no = cmd->host->unique_id;
    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));

    r = ppa_wait(host_no); /* Need a ppa_wait() - PJC */

    while (r != (unsigned char) 0xf0) {
        /*
         * 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;

        if (((r & 0xc0) != 0xc0) || (cmd->SCp.this_residual <= 0)) {
            ppa_fail(host_no, DID_ERROR);
            return -1;          /* ERROR_RETURN */
        }
        /* determine if we should use burst I/O */ fast = (bulk && (cmd->SCp.this_residual >= PPA_BURST_SIZE))
            ? PPA_BURST_SIZE : 1;

        if (r == (unsigned char) 0xc0)
            status = ppa_out(host_no, cmd->SCp.ptr, fast);
        else
            status = ppa_in(host_no, cmd->SCp.ptr, fast);

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

        if (!status) {
            ppa_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;
            }
        }
        /* Now check to see if the drive is ready to comunicate */
        r = ppa_wait(host_no); /* need ppa_wait() - PJC */
        /* 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 ppa_command(Scsi_Cmnd * cmd)
{
    static int first_pass = 1;
    int host_no = cmd->host->unique_id;

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

    ppa_pb_claim(host_no);

    while (ppa_engine(&ppa_hosts[host_no], cmd))
        schedule();

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

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

/*
 * Since the PPA 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 ppa_interrupt(void *data)
{
    ppa_struct *tmp = (ppa_struct *) data;
    Scsi_Cmnd *cmd = tmp->cur_cmd;
    unsigned long flags;

    if (!cmd) {
        printk("PPA: bug in ppa_interrupt\n");
        return;
    }
    if (ppa_engine(tmp, cmd)) {
        tmp->ppa_tq.data = (void *) tmp;
        tmp->ppa_tq.sync = 0;
        queue_task(&tmp->ppa_tq, &tq_timer);
        return;
    }
    /* Command must of completed hence it is safe to let go... */
#if PPA_DEBUG > 0
    switch ((cmd->result >> 16) & 0xff) {
    case DID_OK:
        break;
    case DID_NO_CONNECT:
        printk("ppa: no device at SCSI ID %i\n", cmd->target);
        break;
    case DID_BUS_BUSY:
        printk("ppa: BUS BUSY - EPP timeout detected\n");
        break;
    case DID_TIME_OUT:
        printk("ppa: unknown timeout\n");
        break;
    case DID_ABORT:
        printk("ppa: told to abort\n");
        break;
    case DID_PARITY:
        printk("ppa: parity error (???)\n");
        break;
    case DID_ERROR:
        printk("ppa: internal driver error\n");
        break;
    case DID_RESET:
        printk("ppa: told to reset device\n");
        break;
    case DID_BAD_INTR:
        printk("ppa: bad interrupt (???)\n");
        break;
    default:
        printk("ppa: bad return code (%02x)\n", (cmd->result >> 16) & 0xff);
    }
#endif

    if (cmd->SCp.phase > 1)
        ppa_disconnect(cmd->host->unique_id);
    if (cmd->SCp.phase > 0)
        ppa_pb_release(cmd->host->unique_id);

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

static int ppa_engine(ppa_struct * tmp, Scsi_Cmnd * cmd)
{
    int host_no = cmd->host->unique_id;
    unsigned short ppb = PPA_BASE(host_no);
    unsigned char l = 0, h = 0;
    int retv;

    /* 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
             */
            ppa_fail(host_no, DID_BUS_BUSY);
            return 0;
        }
        return 1;               /* wait until ppa_wakeup claims parport */
    case 1:                     /* Phase 1 - Connected */
        {                       /* Perform a sanity check for cable unplugged */
            int retv = 2;       /* Failed */

            ppa_connect(host_no, CONNECT_EPP_MAYBE);

            w_ctr(ppb, 0xe);
            if ((r_str(ppb) & 0x08) == 0x08)
                retv--;

            w_ctr(ppb, 0xc);
            if ((r_str(ppb) & 0x08) == 0x00)
                retv--;

            if (retv) {
                if ((jiffies - tmp->jstart) > (1 * HZ)) {
                    printk("ppa: Parallel port cable is unplugged!!\n");
                    ppa_fail(host_no, DID_BUS_BUSY);
                    return 0;
                } else {
                    ppa_disconnect(host_no);
                    return 1;   /* Try again in a jiffy */
                }
            }
            cmd->SCp.phase++;
        }

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

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

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

    case 4:                     /* Phase 4 - Setup scatter/gather buffers */
        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++;

    case 5:                     /* Phase 5 - Data transfer stage */
        w_ctr(ppb, 0x0c);
        if (!(r_str(ppb) & 0x80))
            return 1;

        retv = ppa_completion(cmd);
        if (retv == -1)
            return 0;
        if (retv == 0)
            return 1;
        cmd->SCp.phase++;

    case 6:                     /* Phase 6 - Read status/message */
        cmd->result = DID_OK << 16;
        /* Check for data overrun */
        if (ppa_wait(host_no) != (unsigned char) 0xf0) {
            ppa_fail(host_no, DID_ERROR);
            return 0;
        }
        if (ppa_in(host_no, &l, 1)) {   /* read status byte */
            /* Check for optional message byte */
            if (ppa_wait(host_no) == (unsigned char) 0xf0)
                ppa_in(host_no, &h, 1);
            cmd->result = (DID_OK << 16) + (h << 8) + (l & STATUS_MASK);
        }
        return 0;               /* Finished */
        break;

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

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

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

    ppa_pb_claim(host_no);

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

    return 0;
}

/*
 * Apparently 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 ppa_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 ppa_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 */
        ppa_hosts[host_no].cur_cmd = NULL;      /* Forget the problem */
        return SUCCESS;
        break;
    default:                    /* SCSI command sent, can not abort */
        return FAILED;
        break;
    }
}

static void ppa_reset_pulse(unsigned int base)
{
    w_dtr(base, 0x40);
    w_ctr(base, 0x8);
    udelay(30);
    w_ctr(base, 0xc);
}

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

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

    ppa_connect(host_no, CONNECT_NORMAL);
    ppa_reset_pulse(PPA_BASE(host_no));
    udelay(1000);               /* device settle delay */
    ppa_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 = PPA_BASE(host_no);
    unsigned char l;

    old_mode = ppa_hosts[host_no].mode;
    for (loop = 0; loop < 8; loop++) {
        /* Attempt to use EPP for Test Unit Ready */
        if ((ppb & 0x0007) == 0x0000)
            ppa_hosts[host_no].mode = PPA_EPP_32;

      second_pass:
        ppa_connect(host_no, CONNECT_EPP_MAYBE);
        /* Select SCSI device */
        if (!ppa_select(host_no, loop)) {
            ppa_disconnect(host_no);
            continue;
        }
        printk("ppa: Found device at ID %i, Attempting to use %s\n", loop,
               PPA_MODE_STRING[ppa_hosts[host_no].mode]);

        /* Send SCSI command */
        status = 1;
        w_ctr(ppb, 0x0c);
        for (l = 0; (l < 6) && (status); l++)
            status = ppa_out(host_no, cmd, 1);

        if (!status) {
            ppa_disconnect(host_no);
            ppa_connect(host_no, CONNECT_EPP_MAYBE);
            w_dtr(ppb, 0x40);
            w_ctr(ppb, 0x08);
            udelay(30);
            w_ctr(ppb, 0x0c);
            udelay(1000);
            ppa_disconnect(host_no);
            udelay(1000);
            if (ppa_hosts[host_no].mode == PPA_EPP_32) {
                ppa_hosts[host_no].mode = old_mode;
                goto second_pass;
            }
            printk("ppa: 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 &= 0xf0;

        if (l != 0xf0) {
            ppa_disconnect(host_no);
            ppa_connect(host_no, CONNECT_EPP_MAYBE);
            ppa_reset_pulse(ppb);
            udelay(1000);
            ppa_disconnect(host_no);
            udelay(1000);
            if (ppa_hosts[host_no].mode == PPA_EPP_32) {
                ppa_hosts[host_no].mode = old_mode;
                goto second_pass;
            }
            printk("ppa: Unable to establish communication, aborting driver load.\n");
            return 1;
        }
        ppa_disconnect(host_no);
        printk("ppa: Communication established with ID %i using %s\n", loop,
               PPA_MODE_STRING[ppa_hosts[host_no].mode]);
        ppa_connect(host_no, CONNECT_EPP_MAYBE);
        ppa_reset_pulse(ppb);
        udelay(1000);
        ppa_disconnect(host_no);
        udelay(1000);
        return 0;
    }
    printk("ppa: No devices found, aborting driver load.\n");
    return 1;
}