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imm.c

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

#include <linux/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 <asm/io.h>

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

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


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

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

#include "imm.h"

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

static DEFINE_SPINLOCK(arbitration_lock);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

      w_ctr(ppb, 0x0c);

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

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

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

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

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

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

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

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

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

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

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

      if (ppb_hi == 0)
            return;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

      if (!k)
            return 0;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

      imm_pb_dismiss(dev);

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

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

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

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

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

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

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

            /* Phase 4 - Setup scatter/gather buffers */
      case 4:
            if (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++;
            if (cmd->SCp.this_residual & 0x01)
                  cmd->SCp.this_residual++;
            /* Phase 5 - Pre-Data transfer stage */
      case 5:
            /* Spin lock for BUSY */
            w_ctr(ppb, 0x0c);
            if (!(r_str(ppb) & 0x80))
                  return 1;

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

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

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

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

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

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

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

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

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

      schedule_delayed_work(&dev->imm_tq, 0);

      imm_pb_claim(dev);

      return 0;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

            l &= 0xb8;

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

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

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

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

static LIST_HEAD(imm_hosts);

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

      init_waitqueue_head(&waiting);

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


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

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

      if (!dev->dev)
            goto out;


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

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

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

      /* Done configuration */

      err = imm_init(dev);

      imm_pb_release(dev);

      if (err)
            goto out1;

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

      INIT_DELAYED_WORK(&dev->imm_tq, imm_interrupt);

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

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

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

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

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

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

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

module_init(imm_driver_init);
module_exit(imm_driver_exit);

MODULE_LICENSE("GPL");

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