/* 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 unofficial 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 <linux/slab.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 int imm_write_info(struct Scsi_Host *host, char *buffer, int length)
  {
  	imm_struct *dev = imm_dev(host);
  
  	if ((length > 5) && (strncmp(buffer, "mode=", 5) == 0)) {
  		dev->mode = simple_strtoul(buffer + 5, NULL, 0);
  		return length;
  	}
  	printk("imm /proc: invalid variable
  ");
  	return -EINVAL;
  }
  
  static int imm_show_info(struct seq_file *m, struct Scsi_Host *host)
  {
  	imm_struct *dev = imm_dev(host);
  
  	seq_printf(m, "Version : %s
  ", IMM_VERSION);
  	seq_printf(m, "Parport : %s
  ", dev->dev->port->name);
  	seq_printf(m, "Mode    : %s
  ", IMM_MODE_STRING[dev->mode]);
  	return 0;
  }
  
  #if IMM_DEBUG > 0
  #define imm_fail(x,y) printk("imm: imm_fail(%i) from %s at line %d
  ",\
  	   y, __func__, __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
  ");
  	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.
  ");
  		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.
  ");
  	}
  }
  
  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
  ", 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()
  ");
  		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()
  ");
  		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
  ", cmd->device->id);
  		break;
  	case DID_BUS_BUSY:
  		printk("imm: BUS BUSY - EPP timeout detected
  ");
  		break;
  	case DID_TIME_OUT:
  		printk("imm: unknown timeout
  ");
  		break;
  	case DID_ABORT:
  		printk("imm: told to abort
  ");
  		break;
  	case DID_PARITY:
  		printk("imm: parity error (???)
  ");
  		break;
  	case DID_ERROR:
  		printk("imm: internal driver error
  ");
  		break;
  	case DID_RESET:
  		printk("imm: told to reset device
  ");
  		break;
  	case DID_BAD_INTR:
  		printk("imm: bad interrupt (???)
  ");
  		break;
  	default:
  		printk("imm: bad return code (%02x)
  ",
  		       (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 (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++;
  		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
  ");
  	}
  	return 0;
  }
  
  static int imm_queuecommand_lck(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
  ");
  		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;
  }
  
  static DEF_SCSI_QCMD(imm_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 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
  ",
  		       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
  ");
  			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
  ");
  			return -EIO;
  		}
  		imm_disconnect(dev);
  		printk
  		    ("imm: Communication established at 0x%x with ID %i using %s
  ",
  		     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
  ");
  	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",
  	.show_info		= imm_show_info,
  	.write_info		= imm_write_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!
  ", 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
  ", 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");