ppa.c

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/* 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, [email protected],
 * under the terms of the GNU General Public License.
 * 
 */

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

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


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                */
    struct scsi_cmnd *cur_cmd;  /* Current queued command       */
    struct delayed_work ppa_tq; /* Polling interrupt stuff       */
    unsigned long jstart;   /* Jiffies at start             */
    unsigned long recon_tmo;    /* How many usecs to wait for reconnection (6th bit) */
    unsigned int failed:1;  /* Failure flag                 */
    unsigned wanted:1;  /* Parport sharing busy flag    */
    wait_queue_head_t *waiting;
    struct Scsi_Host *host;
    struct list_head list;
} ppa_struct;

#include  "ppa.h"

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

static DEFINE_SPINLOCK(arbitration_lock);

static void got_it(ppa_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 ppa_wakeup(void *ref)
{
    ppa_struct *dev = (ppa_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);
    return;
}

static int ppa_pb_claim(ppa_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 ppa_pb_dismiss(ppa_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 ppa_pb_release(ppa_struct *dev)
{
    parport_release(dev->dev);
}

/*
 * Start of Chipset kludges
 */

/* 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(ppa_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;
    }
    if ((length > 10) && (strncmp(buffer, "recon_tmo=", 10) == 0)) {
        x = simple_strtoul(buffer + 10, NULL, 0);
        dev->recon_tmo = x;
        printk(KERN_INFO "ppa: recon_tmo set to %ld\n", x);
        return length;
    }
    printk(KERN_WARNING "ppa /proc: invalid variable\n");
    return -EINVAL;
}

static int ppa_proc_info(struct Scsi_Host *host, char *buffer, char **start, off_t offset, int length, int inout)
{
    int len = 0;
    ppa_struct *dev = ppa_dev(host);

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

    len += sprintf(buffer + len, "Version : %s\n", PPA_VERSION);
    len +=
        sprintf(buffer + len, "Parport : %s\n",
            dev->dev->port->name);
    len +=
        sprintf(buffer + len, "Mode    : %s\n",
            PPA_MODE_STRING[dev->mode]);
#if PPA_DEBUG > 0
    len +=
        sprintf(buffer + len, "recon_tmo : %lu\n", dev->recon_tmo);
#endif

    /* 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(ppa_struct *dev);

#if PPA_DEBUG > 0
#define ppa_fail(x,y) printk("ppa: ppa_fail(%i) from %s at line %d\n",\
       y, __func__, __LINE__); ppa_fail_func(x,y);
static inline void ppa_fail_func(ppa_struct *dev, int error_code)
#else
static inline void ppa_fail(ppa_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 ppa_wait(ppa_struct *dev)
{
    int k;
    unsigned short ppb = dev->base;
    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(dev, DID_TIME_OUT);
    printk(KERN_WARNING "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(ppa_struct *dev)
{
    int i, ppb_hi = dev->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(KERN_WARNING "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(ppa_struct *dev, char *buffer, int len)
{
    int r;
    unsigned short ppb = dev->base;

    r = ppa_wait(dev);

    if ((r & 0x50) != 0x40) {
        ppa_fail(dev, DID_ERROR);
        return 0;
    }
    switch (dev->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(dev);
        break;

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

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

    r = ppa_wait(dev);

    if ((r & 0x50) != 0x50) {
        ppa_fail(dev, DID_ERROR);
        return 0;
    }
    switch (dev->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(dev);
        break;

    default:
        printk(KERN_ERR "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(ppa_struct *dev)
{
    unsigned short ppb = dev->base;

    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(ppa_struct *dev, int flag)
{
    unsigned short ppb = dev->base;

    ppa_c_pulse(ppb, 0);
    ppa_c_pulse(ppb, 0x3c);
    ppa_c_pulse(ppb, 0x20);
    if ((flag == CONNECT_EPP_MAYBE) && IN_EPP_MODE(dev->mode))
        ppa_c_pulse(ppb, 0xcf);
    else
        ppa_c_pulse(ppb, 0x8f);
}

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

    /*
     * 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--;
        udelay(1);
    } 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--;
        udelay(1);
    }
    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(ppa_struct *dev)
{
    int retv;
    unsigned short ppb = dev->base;

    ppa_disconnect(dev);
    ppa_connect(dev, 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(dev);
    udelay(1000);       /* Another delay to allow devices to settle */

    if (retv)
        return -EIO;

    return device_check(dev);
}

static inline int ppa_send_command(struct scsi_cmnd *cmd)
{
    ppa_struct *dev = ppa_dev(cmd->device->host);
    int k;

    w_ctr(dev->base, 0x0c);

    for (k = 0; k < cmd->cmd_len; k++)
        if (!ppa_out(dev, &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(struct scsi_cmnd *cmd)
{
    /* Return codes:
     * -1     Error
     *  0     Told to schedule
     *  1     Finished data transfer
     */
    ppa_struct *dev = ppa_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 ppa_wait.
     */
    r = (r_str(ppb) & 0xf0);

    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 ((cmd->SCp.this_residual <= 0)) {
            ppa_fail(dev, DID_ERROR);
            return -1;  /* ERROR_RETURN */
        }

        /* On some hardware we have SCSI disconnected (6th bit low)
         * for about 100usecs. It is too expensive to wait a 
         * tick on every loop so we busy wait for no more than
         * 500usecs to give the drive a chance first. We do not 
         * change things for "normal" hardware since generally 
         * the 6th bit is always high.
         * This makes the CPU load higher on some hardware 
         * but otherwise we can not get more than 50K/secs 
         * on this problem hardware.
         */
        if ((r & 0xc0) != 0xc0) {
            /* Wait for reconnection should be no more than 
             * jiffy/2 = 5ms = 5000 loops
             */
            unsigned long k = dev->recon_tmo;
            for (; k && ((r = (r_str(ppb) & 0xf0)) & 0xc0) != 0xc0;
                 k--)
                udelay(1);

            if (!k)
                return 0;
        }

        /* 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(dev, cmd->SCp.ptr, fast);
        else
            status = ppa_in(dev, cmd->SCp.ptr, fast);

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

        if (!status) {
            ppa_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);
            }
        }
        /* Now check to see if the drive is ready to comunicate */
        r = (r_str(ppb) & 0xf0);
        /* If not, drop back down to the scheduler and wait a timer tick */
        if (!(r & 0x80))
            return 0;
    }
    return 1;       /* FINISH_RETURN */
}

/*
 * 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(struct work_struct *work)
{
    ppa_struct *dev = container_of(work, ppa_struct, ppa_tq.work);
    struct scsi_cmnd *cmd = dev->cur_cmd;

    if (!cmd) {
        printk(KERN_ERR "PPA: bug in ppa_interrupt\n");
        return;
    }
    if (ppa_engine(dev, cmd)) {
        schedule_delayed_work(&dev->ppa_tq, 1);
        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(KERN_DEBUG "ppa: no device at SCSI ID %i\n", cmd->device->target);
        break;
    case DID_BUS_BUSY:
        printk(KERN_DEBUG "ppa: BUS BUSY - EPP timeout detected\n");
        break;
    case DID_TIME_OUT:
        printk(KERN_DEBUG "ppa: unknown timeout\n");
        break;
    case DID_ABORT:
        printk(KERN_DEBUG "ppa: told to abort\n");
        break;
    case DID_PARITY:
        printk(KERN_DEBUG "ppa: parity error (???)\n");
        break;
    case DID_ERROR:
        printk(KERN_DEBUG "ppa: internal driver error\n");
        break;
    case DID_RESET:
        printk(KERN_DEBUG "ppa: told to reset device\n");
        break;
    case DID_BAD_INTR:
        printk(KERN_WARNING "ppa: bad interrupt (???)\n");
        break;
    default:
        printk(KERN_WARNING "ppa: bad return code (%02x)\n",
               (cmd->result >> 16) & 0xff);
    }
#endif

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

    ppa_pb_dismiss(dev);

    dev->cur_cmd = NULL;

    cmd->scsi_done(cmd);
}

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

    /* First check for any errors that may of 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
             */
            ppa_fail(dev, 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(dev, 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 (time_after(jiffies, dev->jstart + (1 * HZ))) {
                    printk(KERN_ERR "ppa: Parallel port cable is unplugged.\n");
                    ppa_fail(dev, DID_BUS_BUSY);
                    return 0;
                } else {
                    ppa_disconnect(dev);
                    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(dev, scmd_id(cmd))) {
            ppa_fail(dev, 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 (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++;

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

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

static int ppa_queuecommand_lck(struct scsi_cmnd *cmd,
        void (*done) (struct scsi_cmnd *))
{
    ppa_struct *dev = ppa_dev(cmd->device->host);

    if (dev->cur_cmd) {
        printk(KERN_ERR "PPA: bug in ppa_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->ppa_tq, 0);

    ppa_pb_claim(dev);

    return 0;
}

static DEF_SCSI_QCMD(ppa_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 ppa_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]);
        if (ip[2] > 1023)
            ip[2] = 1023;
    }
    return 0;
}

static int ppa_abort(struct scsi_cmnd *cmd)
{
    ppa_struct *dev = ppa_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 ppa_reset_pulse(unsigned int base)
{
    w_dtr(base, 0x40);
    w_ctr(base, 0x8);
    udelay(30);
    w_ctr(base, 0xc);
}

static int ppa_reset(struct scsi_cmnd *cmd)
{
    ppa_struct *dev = ppa_dev(cmd->device->host);

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

    ppa_connect(dev, CONNECT_NORMAL);
    ppa_reset_pulse(dev->base);
    mdelay(1);      /* device settle delay */
    ppa_disconnect(dev);
    mdelay(1);      /* device settle delay */
    return SUCCESS;
}

static int device_check(ppa_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 u8 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 = PPA_EPP_32;

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

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

        if (!status) {
            ppa_disconnect(dev);
            ppa_connect(dev, CONNECT_EPP_MAYBE);
            w_dtr(ppb, 0x40);
            w_ctr(ppb, 0x08);
            udelay(30);
            w_ctr(ppb, 0x0c);
            udelay(1000);
            ppa_disconnect(dev);
            udelay(1000);
            if (dev->mode == PPA_EPP_32) {
                dev->mode = old_mode;
                goto second_pass;
            }
            return -EIO;
        }
        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(dev);
            ppa_connect(dev, CONNECT_EPP_MAYBE);
            ppa_reset_pulse(ppb);
            udelay(1000);
            ppa_disconnect(dev);
            udelay(1000);
            if (dev->mode == PPA_EPP_32) {
                dev->mode = old_mode;
                goto second_pass;
            }
            return -EIO;
        }
        ppa_disconnect(dev);
        printk(KERN_INFO "ppa: Communication established with ID %i using %s\n",
               loop, PPA_MODE_STRING[dev->mode]);
        ppa_connect(dev, CONNECT_EPP_MAYBE);
        ppa_reset_pulse(ppb);
        udelay(1000);
        ppa_disconnect(dev);
        udelay(1000);
        return 0;
    }
    return -ENODEV;
}

static int ppa_adjust_queue(struct scsi_device *device)
{
    blk_queue_bounce_limit(device->request_queue, BLK_BOUNCE_HIGH);
    return 0;
}

static struct scsi_host_template ppa_template = {
    .module         = THIS_MODULE,
    .proc_name      = "ppa",
    .proc_info      = ppa_proc_info,
    .name           = "Iomega VPI0 (ppa) interface",
    .queuecommand       = ppa_queuecommand,
    .eh_abort_handler   = ppa_abort,
    .eh_bus_reset_handler   = ppa_reset,
    .eh_host_reset_handler  = ppa_reset,
    .bios_param     = ppa_biosparam,
    .this_id        = -1,
    .sg_tablesize       = SG_ALL,
    .cmd_per_lun        = 1,
    .use_clustering     = ENABLE_CLUSTERING,
    .can_queue      = 1,
    .slave_alloc        = ppa_adjust_queue,
};

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

static LIST_HEAD(ppa_hosts);

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

    dev = kzalloc(sizeof(ppa_struct), GFP_KERNEL);
    if (!dev)
        return -ENOMEM;
    dev->base = -1;
    dev->mode = PPA_AUTODETECT;
    dev->recon_tmo = PPA_RECON_TMO;
    init_waitqueue_head(&waiting);
    dev->dev = parport_register_device(pb, "ppa", NULL, ppa_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 (ppa_pb_claim(dev))
        schedule_timeout(3 * HZ);
    if (dev->wanted) {
        printk(KERN_ERR "ppa%d: failed to claim parport because "
                "a pardevice is owning the port for too long "
                "time!\n", pb->number);
        ppa_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;
    ppb_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 = PPA_NIBBLE;

    if (modes & PARPORT_MODE_TRISTATE)
        dev->mode = PPA_PS2;

    if (modes & PARPORT_MODE_ECP) {
        w_ecr(ppb_hi, 0x20);
        dev->mode = PPA_PS2;
    }
    if ((modes & PARPORT_MODE_EPP) && (modes & PARPORT_MODE_ECP))
        w_ecr(ppb_hi, 0x80);

    /* Done configuration */

    err = ppa_init(dev);
    ppa_pb_release(dev);

    if (err)
        goto out1;

    /* now the glue ... */
    if (dev->mode == PPA_NIBBLE || dev->mode == PPA_PS2)
        ports = 3;
    else
        ports = 8;

    INIT_DELAYED_WORK(&dev->ppa_tq, ppa_interrupt);

    err = -ENOMEM;
    host = scsi_host_alloc(&ppa_template, sizeof(ppa_struct *));
    if (!host)
        goto out1;
    host->io_port = pb->base;
    host->n_io_port = ports;
    host->dma_channel = -1;
    host->unique_id = pb->number;
    *(ppa_struct **)&host->hostdata = dev;
    dev->host = host;
    list_add_tail(&dev->list, &ppa_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 ppa_attach(struct parport *pb)
{
    __ppa_attach(pb);
}

static void ppa_detach(struct parport *pb)
{
    ppa_struct *dev;
    list_for_each_entry(dev, &ppa_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 ppa_driver = {
    .name   = "ppa",
    .attach = ppa_attach,
    .detach = ppa_detach,
};

static int __init ppa_driver_init(void)
{
    printk(KERN_INFO "ppa: Version %s\n", PPA_VERSION);
    return parport_register_driver(&ppa_driver);
}

static void __exit ppa_driver_exit(void)
{
    parport_unregister_driver(&ppa_driver);
}

module_init(ppa_driver_init);
module_exit(ppa_driver_exit);
MODULE_LICENSE("GPL");