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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 General Public License.
 * 
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/parport.h>
#include <linux/workqueue.h>
#include <linux/delay.h>
#include <linux/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, __FUNCTION__, __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 (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 = sg_virt(cmd->SCp.buffer);
            } 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 - 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(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;
}

/*
 * 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");

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