/* 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/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
  ", x);

  		return length;
  	}

  	printk(KERN_WARNING "ppa /proc: invalid variable
  ");
  	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
  ", PPA_VERSION);
  	len +=
  	    sprintf(buffer + len, "Parport : %s
  ",
  		    dev->dev->port->name);
  	len +=
  	    sprintf(buffer + len, "Mode    : %s
  ",
  		    PPA_MODE_STRING[dev->mode]);
  #if PPA_DEBUG > 0
  	len +=
  	    sprintf(buffer + len, "recon_tmo : %lu
  ", 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
  ",\

  	   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
  ");

  	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.
  ");

  	}
  }
  
  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()
  ");

  		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()
  ");

  		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
  ");

  		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
  ", cmd->device->target);

  		break;
  	case DID_BUS_BUSY:

  		printk(KERN_DEBUG "ppa: BUS BUSY - EPP timeout detected
  ");

  		break;
  	case DID_TIME_OUT:

  		printk(KERN_DEBUG "ppa: unknown timeout
  ");

  		break;
  	case DID_ABORT:

  		printk(KERN_DEBUG "ppa: told to abort
  ");

  		break;
  	case DID_PARITY:

  		printk(KERN_DEBUG "ppa: parity error (???)
  ");

  		break;
  	case DID_ERROR:

  		printk(KERN_DEBUG "ppa: internal driver error
  ");

  		break;
  	case DID_RESET:

  		printk(KERN_DEBUG "ppa: told to reset device
  ");

  		break;
  	case DID_BAD_INTR:

  		printk(KERN_WARNING "ppa: bad interrupt (???)
  ");

  		break;
  	default:

  		printk(KERN_WARNING "ppa: bad return code (%02x)
  ",

  		       (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.
  ");

  					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
  ");

  	}
  	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
  ");

  		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
  ",

  		       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
  ",

  		       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!
  ", 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
  ", 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");