drivers/scsi/seagate.c

/*
 *	seagate.c Copyright (C) 1992, 1993 Drew Eckhardt 
 *	low level scsi driver for ST01/ST02, Future Domain TMC-885, 
 *	TMC-950  by
 *
 *		Drew Eckhardt 
 *
 *	<drew@colorado.edu>
 *
 * 	Note : TMC-880 boards don't work because they have two bits in 
 *		the status register flipped, I'll fix this "RSN"
 *
 *      This card does all the I/O via memory mapped I/O, so there is no need
 *      to check or snarf a region of the I/O address space.
 */

/*
 * Configuration : 
 * To use without BIOS -DOVERRIDE=base_address -DCONTROLLER=FD or SEAGATE
 * -DIRQ will overide the default of 5.
 * Note: You can now set these options from the kernel's "command line".
 * The syntax is:
 *
 *     st0x=ADDRESS,IRQ                (for a Seagate controller)
 * or:
 *     tmc8xx=ADDRESS,IRQ              (for a TMC-8xx or TMC-950 controller)
 * eg:
 *     tmc8xx=0xC8000,15
 *
 * will configure the driver for a TMC-8xx style controller using IRQ 15
 * with a base address of 0xC8000.
 * 
 * -DFAST or -DFAST32 will use blind transfers where possible
 *
 * -DARBITRATE will cause the host adapter to arbitrate for the 
 *	bus for better SCSI-II compatability, rather than just 
 *	waiting for BUS FREE and then doing its thing.  Should
 *	let us do one command per Lun when I integrate my 
 *	reorganization changes into the distribution sources.
 *
 * -DSLOW_HANDSHAKE will allow compatability with broken devices that don't 
 *	handshake fast enough (ie, some CD ROM's) for the Seagate
 * 	code.
 *
 * -DSLOW_RATE=x, x some number will let you specify a default 
 *	transfer rate if handshaking isn't working correctly.
 */

#include <linux/config.h>

#if defined(CONFIG_SCSI_SEAGATE) || defined(CONFIG_SCSI_FD_8xx) 
#include <asm/io.h>
#include <asm/system.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/string.h>
#include "../block/blk.h"
#include "scsi.h"
#include "hosts.h"
#include "seagate.h"
#include "constants.h"


#ifndef IRQ
#define IRQ 5
#endif

#if (defined(FAST32) && !defined(FAST))
#define FAST
#endif

#if defined(SLOW_RATE) && !defined(SLOW_HANDSHAKE)
#define SLOW_HANDSHAKE
#endif

#if defined(SLOW_HANDSHAKE) && !defined(SLOW_RATE)
#define SLOW_RATE 50
#endif


#if defined(LINKED)
#undef LINKED		/* Linked commands are currently broken ! */
#endif

static int internal_command(unsigned char target, unsigned char lun,
			    const void *cmnd,
			 void *buff, int bufflen, int reselect);

static int incommand;			/*
						set if arbitration has finished and we are 
						in some command phase.
					*/

static void *base_address = NULL;	/*
						Where the card ROM starts,
						used to calculate memory mapped
						register location.
					*/
static volatile int abort_confirm = 0;

static volatile void *st0x_cr_sr;       /*
						control register write,
						status register read.
						256 bytes in length.

						Read is status of SCSI BUS,
						as per STAT masks.

					*/


static volatile void *st0x_dr;         /*
						data register, read write
						256 bytes in length.
					*/


static volatile int st0x_aborted=0;	/* 
						set when we are aborted, ie by a time out, etc.
					*/

static unsigned char controller_type = 0; /* set to SEAGATE for ST0x boards or FD for TMC-8xx boards */
static unsigned char irq = IRQ;
			
#define retcode(result) (((result) << 16) | (message << 8) | status) 			
#define STATUS (*(volatile unsigned char *) st0x_cr_sr)
#define CONTROL STATUS 
#define DATA (*(volatile unsigned char *) st0x_dr)

void st0x_setup (char *str, int *ints) {
    controller_type = SEAGATE;
    base_address = (void *) ints[1];
    irq = ints[2];
}

void tmc8xx_setup (char *str, int *ints) {
    controller_type = FD;
    base_address = (void *) ints[1];
    irq = ints[2];
}
    

#ifndef OVERRIDE		
static const char *  seagate_bases[] = {
	(char *) 0xc8000, (char *) 0xca000, (char *) 0xcc000,
	(char *) 0xce000, (char *) 0xdc000, (char *) 0xde000
};

typedef struct {
	char *signature ;
	unsigned offset;
	unsigned length;
	unsigned char type;
} Signature;
	
static const Signature signatures[] = {
#ifdef CONFIG_SCSI_SEAGATE
{"ST01 v1.7  (C) Copyright 1987 Seagate", 15, 37, SEAGATE},
{"SCSI BIOS 2.00  (C) Copyright 1987 Seagate", 15, 40, SEAGATE},

/*
 * The following two lines are NOT mistakes.  One detects ROM revision 
 * 3.0.0, the other 3.2.  Since seagate has only one type of SCSI adapter, 
 * and this is not going to change, the "SEAGATE" and "SCSI" together
 * are probably "good enough"
 */

{"SEAGATE SCSI BIOS ",16, 17, SEAGATE},
{"SEAGATE SCSI BIOS ",17, 17, SEAGATE},

/*
 * However, future domain makes several incompatable SCSI boards, so specific
 * signatures must be used.
 */

{"FUTURE DOMAIN CORP. (C) 1986-1989 V5.0C2/14/89", 5, 46, FD},
{"FUTURE DOMAIN CORP. (C) 1986-1989 V6.0A7/28/89", 5, 46, FD},
{"FUTURE DOMAIN CORP. (C) 1986-1990 V6.0105/31/90",5, 47, FD},
{"FUTURE DOMAIN CORP. (C) 1986-1990 V6.0209/18/90",5, 47, FD},
{"FUTURE DOMAIN CORP. (C) 1986-1990 V7.009/18/90", 5, 46, FD},
{"FUTURE DOMAIN CORP. (C) 1992 V8.00.004/02/92",   5, 44, FD},
{"FUTURE DOMAIN TMC-950",                        5, 21, FD},
#endif /* CONFIG_SCSI_SEAGATE */
}
;

#define NUM_SIGNATURES (sizeof(signatures) / sizeof(Signature))
#endif /* n OVERRIDE */

/*
 * hostno stores the hostnumber, as told to us by the init routine.
 */

static int hostno = -1;
static void seagate_reconnect_intr(int);

#ifdef FAST
static int fast = 1;
#endif 

#ifdef SLOW_HANDSHAKE
/* 
 * Support for broken devices : 
 * The Seagate board has a handshaking problem.  Namely, a lack 
 * thereof for slow devices.  You can blast 600K/second through 
 * it if you are polling for each byte, more if you do a blind 
 * transfer.  In the first case, with a fast device, REQ will 
 * transition high-low or high-low-high before your loop restarts 
 * and you'll have no problems.  In the second case, the board 
 * will insert wait states for up to 13.2 usecs for REQ to 
 * transition low->high, and everything will work.
 *
 * However, there's nothing in the state machine that says 
 * you *HAVE* to see a high-low-high set of transitions before
 * sending the next byte, and slow things like the Trantor CD ROMS
 * will break because of this.
 * 
 * So, we need to slow things down, which isn't as simple as it 
 * seems.  We can't slow things down period, because then people
 * who don't recompile their kernels will shoot me for ruining 
 * their performance.  We need to do it on a case per case basis.
 *
 * The best for performance will be to, only for borken devices 
 * (this is stored on a per-target basis in the scsi_devices array)
 * 
 * Wait for a low->high transition before continuing with that 
 * transfer.  If we timeout, continue anyways.  We don't need 
 * a long timeout, because REQ should only be asserted until the 
 * corresponding ACK is recieved and processed.
 *
 * Note that we can't use the system timer for this, because of 
 * resolution, and we *really* can't use the timer chip since 
 * gettimeofday() and the beeper routines use that.  So,
 * the best thing for us to do will be to calibrate a timing
 * loop in the initialization code using the timer chip before
 * gettimeofday() can screw with it.
 */

static int borken_calibration = 0;
static void borken_init (void) {
  register int count = 0, start = jiffies + 1, stop = start + 25;

  while (jiffies < start);
  for (;jiffies < stop; ++count);

/* 
 * Ok, we now have a count for .25 seconds.  Convert to a 
 * count per second and divide by transer rate in K.
 */

  borken_calibration =  (count * 4) / (SLOW_RATE*1024);

  if (borken_calibration < 1)
  	borken_calibration = 1;
#if (DEBUG & DEBUG_BORKEN)
  printk("scsi%d : borken calibrated to %dK/sec, %d cycles per transfer\n", 
	hostno, BORKEN_RATE, borken_calibration);
#endif
}

static inline void borken_wait(void) {
  register int count;
  for (count = borken_calibration; count && (STATUS & STAT_REQ); 
  	--count);
  if (count)
#if (DEBUG & DEBUG_BORKEN) 
  	printk("scsi%d : borken timeout\n", hostno);
#else
	;
#endif 
}

#endif /* def SLOW_HANDSHAKE */

int seagate_st0x_detect (int hostnum)
	{
#ifndef OVERRIDE
	int i,j;
#endif 
static struct sigaction seagate_sigaction = {
	&seagate_reconnect_intr,
	0,
	SA_INTERRUPT,
	NULL
};

/*
 *	First, we try for the manual override.
 */
#ifdef DEBUG 
	printk("Autodetecting seagate ST0x\n");
#endif
	
	if (hostno != -1)
		{
		printk ("ERROR : seagate_st0x_detect() called twice.\n");
		return 0;
		}

      /* If the user specified the controller type from the command line,
         controller_type will be non-zero, so don't try and detect one */

	if (!controller_type) {
#ifdef OVERRIDE
	base_address = (void *) OVERRIDE;

/* CONTROLLER is used to override controller (SEAGATE or FD). PM: 07/01/93 */
#ifdef CONTROLLER
	controller_type = CONTROLLER;
#else
#error Please use -DCONTROLLER=SEAGATE or -DCONTROLLER=FD to override controller type
#endif /* CONTROLLER */
#ifdef DEBUG
	printk("Base address overridden to %x, controller type is %s\n",
		base_address,controller_type == SEAGATE ? "SEAGATE" : "FD");
#endif 
#else /* OVERIDE */	
/*
 *	To detect this card, we simply look for the signature
 *	from the BIOS version notice in all the possible locations
 *	of the ROM's.  This has a nice sideeffect of not trashing
 * 	any register locations that might be used by something else.
 *
 * XXX - note that we probably should be probing the address
 * space for the on-board RAM instead.
 */

	for (i = 0; i < (sizeof (seagate_bases) / sizeof (char  * )); ++i)
		for (j = 0; !base_address && j < NUM_SIGNATURES; ++j)
		if (!memcmp ((void *) (seagate_bases[i] +
		    signatures[j].offset), (void *) signatures[j].signature,
		    signatures[j].length)) {
			base_address = (void *) seagate_bases[i];
			controller_type = signatures[j].type;
		}
#endif /* OVERIDE */
	} /* (! controller_type) */
 
	scsi_hosts[hostnum].this_id = (controller_type == SEAGATE) ? 7 : 6;

	if (base_address)
		{
		st0x_cr_sr =(void *) (((unsigned char *) base_address) + (controller_type == SEAGATE ? 0x1a00 : 0x1c00)); 
		st0x_dr = (void *) (((unsigned char *) base_address ) + (controller_type == SEAGATE ? 0x1c00 : 0x1e00));
#ifdef DEBUG
		printk("ST0x detected. Base address = %x, cr = %x, dr = %x\n", base_address, st0x_cr_sr, st0x_dr);
#endif
/*
 *	At all times, we will use IRQ 5.  Should also check for IRQ3 if we 
 * 	loose our first interrupt.
 */
		hostno = hostnum;
		if (irqaction((int) irq, &seagate_sigaction)) {
			printk("scsi%d : unable to allocate IRQ%d\n",
				hostno, (int) irq);
			return 0;
		}
#ifdef SLOW_HANDSHAKE
		borken_init();
#endif
		
		return 1;
		}
	else
		{
#ifdef DEBUG
		printk("ST0x not detected.\n");
#endif
		return 0;
		}
	}
	 
const char *seagate_st0x_info(void) {
      static char buffer[256];
        sprintf(buffer, "scsi%d : %s at irq %d address %p options :"
#ifdef ARBITRATE
" ARBITRATE"
#endif
#ifdef SLOW_HANDSHAKE
" SLOW_HANDSHAKE"
#endif
#ifdef FAST
#ifdef FAST32
" FAST32"
#else
" FAST"
#endif
#endif
 
#ifdef LINKED
" LINKED"
#endif
              "\n", hostno, (controller_type == SEAGATE) ? "seagate" : 
              "FD TMC-8xx", irq, base_address);
        return buffer;
}

/*
 * These are our saved pointers for the outstanding command that is 
 * waiting for a reconnect
 */

static unsigned char current_target, current_lun;
static unsigned char *current_cmnd, *current_data;
static int current_nobuffs;
static struct scatterlist *current_buffer;
static int current_bufflen;

#ifdef LINKED

/* 
 * linked_connected indicates weather or not we are currently connected to 
 * linked_target, linked_lun and in an INFORMATION TRANSFER phase,
 * using linked commands.
 */

static int linked_connected = 0;
static unsigned char linked_target, linked_lun;
#endif


static void (*done_fn)(Scsi_Cmnd *) = NULL;
static Scsi_Cmnd * SCint = NULL;

/*
 * These control whether or not disconnect / reconnect will be attempted,
 * or are being attempted.
 */

#define NO_RECONNECT 	0
#define RECONNECT_NOW 	1
#define CAN_RECONNECT	2

#ifdef LINKED

/*
 * LINKED_RIGHT indicates that we are currently connected to the correct target
 * for this command, LINKED_WRONG indicates that we are connected to the wrong 
 * target.  Note that these imply CAN_RECONNECT.
 */

#define LINKED_RIGHT 	3
#define LINKED_WRONG	4
#endif

/*
 * This determines if we are expecting to reconnect or not.
 */

static int should_reconnect = 0;

/*
 * The seagate_reconnect_intr routine is called when a target reselects the 
 * host adapter.  This occurs on the interrupt triggered by the target 
 * asserting SEL.
 */

static void seagate_reconnect_intr (int unused)
	{
	int temp;
	Scsi_Cmnd * SCtmp;

/* enable all other interrupts. */	
	sti();
#if (DEBUG & PHASE_RESELECT)
	printk("scsi%d : seagate_reconnect_intr() called\n", hostno);
#endif

	if (!should_reconnect)
	    printk("scsi%d: unexpected interrupt.\n", hostno);
	else {
		 should_reconnect = 0;

#if (DEBUG & PHASE_RESELECT)
		printk("scsi%d : internal_command("
		       "%d, %08x, %08x, %d, RECONNECT_NOW\n", hostno, 
			current_target, current_data, current_bufflen);
#endif
	
		temp =  internal_command (current_target, current_lun,
			current_cmnd, current_data, current_bufflen,
			RECONNECT_NOW);

		if (msg_byte(temp) != DISCONNECT) {
			if (done_fn) {
#if (DEBUG & PHASE_RESELECT)
				printk("scsi%d : done_fn(%d,%08x)", hostno, 
				hostno, temp);
#endif
				if(!SCint) panic("SCint == NULL in seagate");
				SCtmp = SCint;
				SCint = NULL;
				SCtmp->result = temp;
				done_fn (SCtmp);
			} else
				printk("done_fn() not defined.\n");
			}
		}
	} 

/* 
 * The seagate_st0x_queue_command() function provides a queued interface
 * to the seagate SCSI driver.  Basically, it just passes control onto the
 * seagate_command() function, after fixing it so that the done_fn()
 * is set to the one passed to the function.  We have to be very careful,
 * because there are some commands on some devices that do not disconnect,
 * and if we simply call the done_fn when the command is done then another
 * command is started and queue_command is called again...  We end up
 * overflowing the kernel stack, and this tends not to be such a good idea.
 */

static int recursion_depth = 0;

int seagate_st0x_queue_command (Scsi_Cmnd * SCpnt,  void (*done)(Scsi_Cmnd *))
	{
	int result, reconnect;
	Scsi_Cmnd * SCtmp;

	done_fn = done;
	current_target = SCpnt->target;
	current_lun = SCpnt->lun;
	(const void *) current_cmnd = SCpnt->cmnd;
	current_data = (unsigned char *) SCpnt->request_buffer;
	current_bufflen = SCpnt->request_bufflen;
	SCint = SCpnt;
	if(recursion_depth) {
	  return 0;
	};
	recursion_depth++;
	do{
#ifdef LINKED
/*
 * Set linked command bit in control field of SCSI command.
 */

	  current_cmnd[COMMAND_SIZE(current_cmnd[0])] |= 0x01;
	  if (linked_connected) {
#if (DEBUG & DEBUG_LINKED) 
	    printk("scsi%d : using linked commands, current I_T_L nexus is ",
	      hostno);
#endif
	    if ((linked_target == current_target) && 
	      (linked_lun == current_lun)) {
#if (DEBUG & DEBUG_LINKED) 
	    printk("correct\n");
#endif
	      reconnect = LINKED_RIGHT;
	    } else {
#if (DEBUG & DEBUG_LINKED) 
	    printk("incorrect\n");
#endif
	      reconnect = LINKED_WRONG;
	    }
	  } else 
#endif /* LINKED */
	    reconnect = CAN_RECONNECT;





	  result = internal_command (SCint->target, SCint->lun, SCint->cmnd, SCint->request_buffer,
				     SCint->request_bufflen, 
				     reconnect);
	  if (msg_byte(result) == DISCONNECT)  break;
	  SCtmp = SCint;
	  SCint = NULL;
	  SCtmp->result = result;
	  done_fn (SCtmp);
	} while(SCint);
	recursion_depth--;
	return 0;
      }

int seagate_st0x_command (Scsi_Cmnd * SCpnt) {
	return internal_command (SCpnt->target, SCpnt->lun, SCpnt->cmnd, SCpnt->request_buffer,
				 SCpnt->request_bufflen, 
				 (int) NO_RECONNECT);
}
	
static int internal_command(unsigned char target, unsigned char lun, const void *cmnd,
			 void *buff, int bufflen, int reselect) {
	int len = 0;
	unsigned char *data = NULL;	
	struct scatterlist *buffer = NULL;
	int nobuffs = 0;
	int clock;			
	int temp;
#ifdef SLOW_HANDSHAKE
	int borken;	/* Does the current target require Very Slow I/O ? */
#endif


#if (DEBUG & PHASE_DATAIN) || (DEBUG & PHASE_DATOUT) 
	int transfered = 0;
#endif

#if (((DEBUG & PHASE_ETC) == PHASE_ETC) || (DEBUG & PRINT_COMMAND) || \
	(DEBUG & PHASE_EXIT))	
	int i;
#endif

#if ((DEBUG & PHASE_ETC) == PHASE_ETC)
	int phase=0, newphase;
#endif

	int done = 0;
	unsigned char status = 0;	
	unsigned char message = 0;
	register unsigned char status_read;

	unsigned transfersize = 0, underflow = 0;

	incommand = 0;
	st0x_aborted = 0;

#ifdef SLOW_HANDSHAKE
	borken = (int) scsi_devices[SCint->index].borken;
#endif

#if (DEBUG & PRINT_COMMAND)
	printk ("scsi%d : target = %d, command = ", hostno, target);
	print_command((unsigned char *) cmnd);
	printk("\n");
#endif

#if (DEBUG & PHASE_RESELECT)
	switch (reselect) {
	case RECONNECT_NOW :
		printk("scsi%d : reconnecting\n", hostno);
		break;
#ifdef LINKED
	case LINKED_RIGHT : 
		printk("scsi%d : connected, can reconnect\n", hostno);
		break;
	case LINKED_WRONG :
		printk("scsi%d : connected to wrong target, can reconnect\n",
			hostno);
		break;		
#endif
	case CAN_RECONNECT :
		printk("scsi%d : allowed to reconnect\n", hostno);
		break;
	default :
		printk("scsi%d : not allowed to reconnect\n", hostno);
	}
#endif
	

	if (target == (controller_type == SEAGATE ? 7 : 6))
		return DID_BAD_TARGET;

/*
 *	We work it differently depending on if this is is "the first time,"
 *	or a reconnect.  If this is a reselct phase, then SEL will 
 *	be asserted, and we must skip selection / arbitration phases.
 */

	switch (reselect) {
	case RECONNECT_NOW:
#if (DEBUG & PHASE_RESELECT)
		printk("scsi%d : phase RESELECT \n", hostno);
#endif

/*
 *	At this point, we should find the logical or of our ID and the original
 *	target's ID on the BUS, with BSY, SEL, and I/O signals asserted.
 *
 *	After ARBITRATION phase is completed, only SEL, BSY, and the 
 *	target ID are asserted.  A valid initator ID is not on the bus
 *	until IO is asserted, so we must wait for that.
 */
		
		for (clock = jiffies + 10, temp = 0; (jiffies < clock) &&
		     !(STATUS & STAT_IO););
		
		if (jiffies >= clock)
			{
#if (DEBUG & PHASE_RESELECT)
			printk("scsi%d : RESELECT timed out while waiting for IO .\n",
				hostno);
#endif
			return (DID_BAD_INTR << 16);
			}

/* 
 * 	After I/O is asserted by the target, we can read our ID and its
 *	ID off of the BUS.
 */
 
		if (!((temp = DATA) & (controller_type == SEAGATE ? 0x80 : 0x40)))
			{
#if (DEBUG & PHASE_RESELECT)
			printk("scsi%d : detected reconnect request to different target.\n" 
			       "\tData bus = %d\n", hostno, temp);
#endif
			return (DID_BAD_INTR << 16);
			}

		if (!(temp & (1 << current_target)))
			{
			printk("scsi%d : Unexpected reselect interrupt.  Data bus = %d\n",
				hostno, temp);
			return (DID_BAD_INTR << 16);
			}

		buffer=current_buffer;	
                cmnd=current_cmnd;      /* WDE add */
                data=current_data;      /* WDE add */
                len=current_bufflen;    /* WDE add */
		nobuffs=current_nobuffs;

/*
 * 	We have determined that we have been selected.  At this point, 
 *	we must respond to the reselection by asserting BSY ourselves
 */

#if 1
		CONTROL = (BASE_CMD | CMD_DRVR_ENABLE | CMD_BSY);
#else
		CONTROL = (BASE_CMD | CMD_BSY);
#endif

/*
 *	The target will drop SEL, and raise BSY, at which time we must drop
 *	BSY.
 */

		for (clock = jiffies + 10; (jiffies < clock) &&  (STATUS & STAT_SEL););

		if (jiffies >= clock)
			{ 
			CONTROL = (BASE_CMD | CMD_INTR);
#if (DEBUG & PHASE_RESELECT)
			printk("scsi%d : RESELECT timed out while waiting for SEL.\n",
				hostno);
#endif
			return (DID_BAD_INTR << 16);				 
			}

		CONTROL = BASE_CMD;

/*
 *	At this point, we have connected with the target and can get 
 *	on with our lives.
 */	 
		break;
	case CAN_RECONNECT:

#ifdef LINKED
/*
 * This is a bletcherous hack, just as bad as the Unix #! interpreter stuff.
 * If it turns out we are using the wrong I_T_L nexus, the easiest way to deal
 * with it is to go into our INFORMATION TRANSFER PHASE code, send a ABORT 
 * message on MESSAGE OUT phase, and then loop back to here.
 */
  
connect_loop :

#endif

#if (DEBUG & PHASE_BUS_FREE)
		printk ("scsi%d : phase = BUS FREE \n", hostno);
#endif

/*
 *	BUS FREE PHASE
 *
 * 	On entry, we make sure that the BUS is in a BUS FREE
 *	phase, by insuring that both BSY and SEL are low for
 *	at least one bus settle delay.  Several reads help
 *	eliminate wire glitch.
 */

		clock = jiffies + ST0X_BUS_FREE_DELAY;	

#if !defined (ARBITRATE) 
		while (((STATUS |  STATUS | STATUS) & 
		         (STAT_BSY | STAT_SEL)) && 
			 (!st0x_aborted) && (jiffies < clock));

		if (jiffies > clock)
			return retcode(DID_BUS_BUSY);
		else if (st0x_aborted)
			return retcode(st0x_aborted);
#endif

#if (DEBUG & PHASE_SELECTION)
		printk("scsi%d : phase = SELECTION\n", hostno);
#endif

		clock = jiffies + ST0X_SELECTION_DELAY;

/*
 * Arbitration/selection procedure : 
 * 1.  Disable drivers
 * 2.  Write HOST adapter address bit
 * 3.  Set start arbitration.
 * 4.  We get either ARBITRATION COMPLETE or SELECT at this
 *     point.
 * 5.  OR our ID and targets on bus.
 * 6.  Enable SCSI drivers and asserted SEL and ATTN
 */
		
#if defined(ARBITRATE)	
	cli();
	CONTROL = 0;
	DATA = (controller_type == SEAGATE) ? 0x80 : 0x40;
	CONTROL = CMD_START_ARB; 
	sti();
	while (!((status_read = STATUS) & (STAT_ARB_CMPL | STAT_SEL)) &&
		(jiffies < clock) && !st0x_aborted);

	if (!(status_read & STAT_ARB_CMPL)) {
#if (DEBUG & PHASE_SELECTION)
		if (status_read & STAT_SEL) 
			printk("scsi%d : arbitration lost\n", hostno);
		else
			printk("scsi%d : arbitration timeout.\n", hostno);
#endif
		CONTROL = BASE_CMD;
		return retcode(DID_NO_CONNECT);
	};

#if (DEBUG & PHASE_SELECTION)
	printk("scsi%d : arbitration complete\n", hostno);
#endif
#endif


/*
 *	When the SCSI device decides that we're gawking at it, it will 
 *	respond by asserting BUSY on the bus.
 *
 * 	Note : the Seagate ST-01/02 product manual says that we should 
 * 	twiddle the DATA register before the control register.  However,
 *	this does not work reliably so we do it the other way arround.
 *
 *	Probably could be a problem with arbitration too, we really should
 *	try this with a SCSI protocol or logic analyzer to see what is 
 *	going on.
 */
	cli();
	DATA = (unsigned char) ((1 << target) | (controller_type == SEAGATE ? 0x80 : 0x40));
	CONTROL = BASE_CMD | CMD_DRVR_ENABLE | CMD_SEL | 
		(reselect ? CMD_ATTN : 0);
	sti();
		while (!((status_read = STATUS) & STAT_BSY) && 
			(jiffies < clock) && !st0x_aborted)

#if 0 && (DEBUG & PHASE_SELECTION)
		{
		temp = clock - jiffies;

		if (!(jiffies % 5))
			printk("seagate_st0x_timeout : %d            \r",temp);
	
		}
		printk("Done.                                             \n");
		printk("scsi%d : status = %02x, seagate_st0x_timeout = %d, aborted = %02x \n", 
			hostno, status_read, temp, st0x_aborted);
#else
		;
#endif
	

		if ((jiffies >= clock)  && !(status_read & STAT_BSY))
			{
#if (DEBUG & PHASE_SELECTION)
			printk ("scsi%d : NO CONNECT with target %d, status = %x \n", 
				hostno, target, STATUS);
#endif
			return retcode(DID_NO_CONNECT);
			}

/*
 *	If we have been aborted, and we have a command in progress, IE the 
 *	target still has BSY asserted, then we will reset the bus, and 
 * 	notify the midlevel driver to expect sense.
 */

		if (st0x_aborted) {
			CONTROL = BASE_CMD;
			if (STATUS & STAT_BSY) {
				printk("scsi%d : BST asserted after we've been aborted.\n",
					hostno);
				seagate_st0x_reset(NULL);
				return retcode(DID_RESET);
			}
			return retcode(st0x_aborted);
		}	

/* Establish current pointers.  Take into account scatter / gather */

        if ((nobuffs = SCint->use_sg)) {
#if (DEBUG & DEBUG_SG)
	{
	int i;
	printk("scsi%d : scatter gather requested, using %d buffers.\n",
		hostno, nobuffs);
	for (i = 0; i < nobuffs; ++i)
		printk("scsi%d : buffer %d address = %08x length = %d\n",
			hostno, i, buffer[i].address, buffer[i].length);
	}
#endif
		
                buffer = (struct scatterlist *) SCint->buffer;
                len = buffer->length;
                data = (unsigned char *) buffer->address;
        } else {
#if (DEBUG & DEBUG_SG)
	printk("scsi%d : scatter gather not requested.\n", hostno);
#endif
                buffer = NULL;
                len = SCint->request_bufflen;
                data = (unsigned char *) SCint->request_buffer;
        }

#if (DEBUG & (PHASE_DATAIN | PHASE_DATAOUT))
	printk("scsi%d : len = %d\n", hostno, len);
#endif

		break;
#ifdef LINKED
	case LINKED_RIGHT:
	    	break;
	case LINKED_WRONG:
		break;
#endif
	}

/*
 * 	There are several conditions under which we wish to send a message : 
 *	1.  When we are allowing disconnect / reconnect, and need to establish
 *	    the I_T_L nexus via an IDENTIFY with the DiscPriv bit set.
 *
 *	2.  When we are doing linked commands, are have the wrong I_T_L nexus
 *	    established and want to send an ABORT message.
 */

	
	CONTROL = BASE_CMD | CMD_DRVR_ENABLE | 
		(((reselect == CAN_RECONNECT)
#ifdef LINKED 
		|| (reselect == LINKED_WRONG)
#endif 
		)  ? CMD_ATTN : 0) ;
	
/*
 * 	INFORMATION TRANSFER PHASE
 *
 *	The nasty looking read / write inline assembler loops we use for 
 *	DATAIN and DATAOUT phases are approximately 4-5 times as fast as 
 *	the 'C' versions - since we're moving 1024 bytes of data, this
 *	really adds up.
 */

#if ((DEBUG & PHASE_ETC) == PHASE_ETC)
	printk("scsi%d : phase = INFORMATION TRANSFER\n", hostno);
#endif  

	incommand = 1;
	transfersize = SCint->transfersize;
	underflow = SCint->underflow;


/*
 * 	Now, we poll the device for status information,
 *	and handle any requests it makes.  Note that since we are unsure of 
 *	how much data will be flowing across the system, etc and cannot 
 *	make reasonable timeouts, that we will instead have the midlevel
 * 	driver handle any timeouts that occur in this phase.
 */

	while (((status_read = STATUS) & STAT_BSY) && !st0x_aborted && !done) 
		{
#ifdef PARITY
		if (status_read & STAT_PARITY)
			{
			printk("scsi%d : got parity error\n", hostno);
			st0x_aborted = DID_PARITY;
			}	
#endif

		if (status_read & STAT_REQ)
			{
#if ((DEBUG & PHASE_ETC) == PHASE_ETC)
			if ((newphase = (status_read & REQ_MASK)) != phase)
				{
				phase = newphase;
				switch (phase)
				{
				case REQ_DATAOUT: 
					printk("scsi%d : phase = DATA OUT\n",
						hostno); 
					break;
				case REQ_DATAIN : 
					printk("scsi%d : phase = DATA IN\n",
						hostno); 
					break;
				case REQ_CMDOUT : 
					printk("scsi%d : phase = COMMAND OUT\n",
						hostno); 
					break;
				case REQ_STATIN :
					 printk("scsi%d : phase = STATUS IN\n",
						hostno); 
					break;
				case REQ_MSGOUT :
					printk("scsi%d : phase = MESSAGE OUT\n",
						hostno); 
					break;
				case REQ_MSGIN :
					printk("scsi%d : phase = MESSAGE IN\n",
						hostno);
					break;
				default : 
					printk("scsi%d : phase = UNKNOWN\n",
						hostno); 
					st0x_aborted = DID_ERROR; 
				}	
				}
#endif
		switch (status_read & REQ_MASK)
		{			
		case REQ_DATAOUT : 
/*
 * If we are in fast mode, then we simply splat the data out
 * in word-sized chunks as fast as we can.
 */

#ifdef FAST 
if (!len) {
#if 0 
        printk("scsi%d: underflow to target %d lun %d \n", 
                hostno, target, lun);
        st0x_aborted = DID_ERROR;
        fast = 0;
#endif
        break;
}

if (fast && transfersize && !(len % transfersize) && (len >= transfersize)
#ifdef FAST32
	&& !(transfersize % 4)
#endif
	) {
#if (DEBUG & DEBUG_FAST) 
        printk("scsi%d : FAST transfer, underflow = %d, transfersize = %d\n"
               "         len = %d, data = %08x\n", hostno, SCint->underflow, 
               SCint->transfersize, len, data);
#endif

        __asm__("
	cld;
"
#ifdef FAST32
"	shr $2, %%ecx;
1:	lodsl;
	movl %%eax, (%%edi);
"
#else
"1:	lodsb;
        movb %%al, (%%edi);
"
#endif
"	loop 1b;" : :
        /* input */
        "D" (st0x_dr), "S" (data), "c" (SCint->transfersize) :
        /* clobbered */
        "eax", "ecx", "esi" );

	len -= transfersize;
	data += transfersize;

#if (DEBUG & DEBUG_FAST)
	printk("scsi%d : FAST transfer complete len = %d data = %08x\n", 
		hostno, len, data);
#endif


} else 
#endif

{
/*
 * 	We loop as long as we are in a data out phase, there is data to send, 
 *	and BSY is still active.
 */
		__asm__ (

/*
	Local variables : 
	len = ecx
	data = esi
	st0x_cr_sr = ebx
	st0x_dr =  edi

	Test for any data here at all.
*/
	"\torl %%ecx, %%ecx
	jz 2f

	cld

	movl _st0x_cr_sr, %%ebx
	movl _st0x_dr, %%edi
	
1:	movb (%%ebx), %%al\n"
/*
	Test for BSY
*/

	"\ttest $1, %%al
	jz 2f\n"

/*
	Test for data out phase - STATUS & REQ_MASK should be REQ_DATAOUT, which is 0.
*/
	"\ttest $0xe, %%al
	jnz 2f	\n"
/*
	Test for REQ
*/	
	"\ttest $0x10, %%al
	jz 1b
	lodsb
	movb %%al, (%%edi) 
	loop 1b

2: 
									":
/* output */
"=S" (data), "=c" (len) :
/* input */
"0" (data), "1" (len) :
/* clobbered */
"eax", "ebx", "edi"); 
}

                        if (!len && nobuffs) {
                                --nobuffs;
                                ++buffer;
                                len = buffer->length;
                                data = (unsigned char *) buffer->address;
#if (DEBUG & DEBUG_SG)
	printk("scsi%d : next scatter-gather buffer len = %d address = %08x\n",
		hostno, len, data);
#endif
                        }
			break;

		case REQ_DATAIN : 
#ifdef SLOW_HANDSHAKE
	if (borken) {
#if (DEBUG & (PHASE_DATAIN))
		transfered += len;
#endif
		for (; len && (STATUS & (REQ_MASK | STAT_REQ)) == (REQ_DATAIN |
			STAT_REQ); --len) {
				*data++ = DATA;
				borken_wait();
}
#if (DEBUG & (PHASE_DATAIN))
		transfered -= len;
#endif
	} else
#endif
#ifdef FAST
if (fast && transfersize && !(len % transfersize) && (len >= transfersize)
#ifdef FAST32
	&& !(transfersize % 4)
#endif
	) {
#if (DEBUG & DEBUG_FAST) 
        printk("scsi%d : FAST transfer, underflow = %d, transfersize = %d\n"
               "         len = %d, data = %08x\n", hostno, SCint->underflow, 
               SCint->transfersize, len, data);
#endif
        __asm__("
	cld;
"
#ifdef FAST32
"	shr $2, %%ecx;
1:	movl (%%esi), %%eax;
	stosl;
"
#else
"1:	movb (%%esi), %%al;
        stosb;
"
#endif

"	loop 1b;" : :
        /* input */
        "S" (st0x_dr), "D" (data), "c" (SCint->transfersize) :
        /* clobbered */
        "eax", "ecx", "edi");

	len -= transfersize;
	data += transfersize;

#if (DEBUG & PHASE_DATAIN)
	printk("scsi%d: transfered += %d\n", hostno, transfersize);
	transfered += transfersize;
#endif

#if (DEBUG & DEBUG_FAST)
	printk("scsi%d : FAST transfer complete len = %d data = %08x\n", 
		hostno, len, data);
#endif

} else
#endif
{

#if (DEBUG & PHASE_DATAIN)
	printk("scsi%d: transfered += %d\n", hostno, len);
	transfered += len;	/* Assume we'll transfer it all, then
				   subtract what we *didn't* transfer */
#endif
	
/*
 * 	We loop as long as we are in a data in phase, there is room to read, 
 * 	and BSY is still active
 */
 
			__asm__ (
/*
	Local variables : 
	ecx = len
	edi = data
	esi = st0x_cr_sr
	ebx = st0x_dr

	Test for room to read
*/
	"\torl %%ecx, %%ecx
	jz 2f

	cld
	movl _st0x_cr_sr, %%esi
	movl _st0x_dr, %%ebx

1:	movb (%%esi), %%al\n"
/*
	Test for BSY
*/

	"\ttest $1, %%al 
	jz 2f\n"

/*
	Test for data in phase - STATUS & REQ_MASK should be REQ_DATAIN, = STAT_IO, which is 4.
*/
	"\tmovb $0xe, %%ah	
	andb %%al, %%ah
	cmpb $0x04, %%ah
	jne 2f\n"
		
/*
	Test for REQ
*/	
	"\ttest $0x10, %%al
	jz 1b

	movb (%%ebx), %%al	
	stosb	
	loop 1b\n"

"2:\n"
									:
/* output */
"=D" (data), "=c" (len) :
/* input */
"0" (data), "1" (len) :
/* clobbered */
"eax","ebx", "esi"); 

#if (DEBUG & PHASE_DATAIN)
	printk("scsi%d: transfered -= %d\n", hostno, len);
	transfered -= len;		/* Since we assumed all of Len got 
					 * transfered, correct our mistake */
#endif
}
	
                        if (!len && nobuffs) {
                                --nobuffs;
                                ++buffer;
                                len = buffer->length;
                                data = (unsigned char *) buffer->address;
#if (DEBUG & DEBUG_SG)
	printk("scsi%d : next scatter-gather buffer len = %d address = %08x\n",
		hostno, len, data);
#endif
                        }

			break;

		case REQ_CMDOUT : 
			while (((status_read = STATUS) & STAT_BSY) && 
			       ((status_read & REQ_MASK) == REQ_CMDOUT))
				if (status_read & STAT_REQ) {
					DATA = *(unsigned char *) cmnd;
					cmnd = 1+(unsigned char *) cmnd;
#ifdef SLOW_HANDSHAKE
					if (borken) 
						borken_wait();
#endif
				}
			break;
	
		case REQ_STATIN : 
			status = DATA;
			break;
				
		case REQ_MSGOUT : 
/*
 *	We can only have sent a MSG OUT if we requested to do this 
 *	by raising ATTN.  So, we must drop ATTN.
 */

			CONTROL = BASE_CMD | CMD_DRVR_ENABLE;
/*
 * 	If we are reconecting, then we must send an IDENTIFY message in 
 *	 response  to MSGOUT.
 */
			switch (reselect) {
			case CAN_RECONNECT:
				DATA = IDENTIFY(1, lun);

#if (DEBUG & (PHASE_RESELECT | PHASE_MSGOUT)) 
				printk("scsi%d : sent IDENTIFY message.\n", hostno);
#endif
				break;
#ifdef LINKED
			case LINKED_WRONG:
				DATA = ABORT;
				linked_connected = 0;
				reselect = CAN_RECONNECT;
				goto connect_loop;
#if (DEBUG & (PHASE_MSGOUT | DEBUG_LINKED))
				printk("scsi%d : sent ABORT message to cancle incorrect I_T_L nexus.\n", hostno);
#endif
#endif /* LINKED */
#if (DEBUG & DEBUG_LINKED) 
	    printk("correct\n");
#endif
			default:
				DATA = NOP;
				printk("scsi%d : target %d requested MSGOUT, sent NOP message.\n", hostno, target);
			}
			break;
					
		case REQ_MSGIN : 
			switch (message = DATA) {
			case DISCONNECT :
				should_reconnect = 1;
                                current_data = data;    /* WDE add */
				current_buffer = buffer;
                                current_bufflen = len;  /* WDE add */
				current_nobuffs = nobuffs;
#ifdef LINKED
				linked_connected = 0;
#endif
				done=1;
#if (DEBUG & (PHASE_RESELECT | PHASE_MSGIN))
				printk("scsi%d : disconnected.\n", hostno);
#endif
				break;

#ifdef LINKED
			case LINKED_CMD_COMPLETE:
			case LINKED_FLG_CMD_COMPLETE:
#endif
			case COMMAND_COMPLETE :
/*
 * Note : we should check for underflow here.   
 */
#if (DEBUG & PHASE_MSGIN)	
				printk("scsi%d : command complete.\n", hostno);
#endif
				done = 1;
				break;
			case ABORT :
#if (DEBUG & PHASE_MSGIN)
				printk("scsi%d : abort message.\n", hostno);
#endif
				done=1;
				break;
			case SAVE_POINTERS :
				current_buffer = buffer;
                                current_bufflen = len;  /* WDE add */
				current_data = data;	/* WDE mod */
				current_nobuffs = nobuffs;
#if (DEBUG & PHASE_MSGIN)
				printk("scsi%d : pointers saved.\n", hostno);
#endif 
				break;
			case RESTORE_POINTERS:
				buffer=current_buffer;
				cmnd=current_cmnd;
				data=current_data;	/* WDE mod */
				len=current_bufflen;
				nobuffs=current_nobuffs;
#if (DEBUG & PHASE_MSGIN)
				printk("scsi%d : pointers restored.\n", hostno);
#endif
				break;
			default:

/*
 * 	IDENTIFY distinguishes itself from the other messages by setting the
 *	high byte.
 * 	
 *	Note : we need to handle at least one outstanding command per LUN,
 *	and need to hash the SCSI command for that I_T_L nexus based on the 
 *	known ID (at this point) and LUN.
 */

				if (message & 0x80) {
#if (DEBUG & PHASE_MSGIN)
					printk("scsi%d : IDENTIFY message received from id %d, lun %d.\n",
						hostno, target, message & 7);
#endif
				} else {

/*
 *      We should go into a MESSAGE OUT phase, and send  a MESSAGE_REJECT 
 * 	if we run into a message that we don't like.  The seagate driver 
 * 	needs some serious restructuring first though.
 */

#if (DEBUG & PHASE_MSGIN)
					printk("scsi%d : unknown message %d from target %d.\n",
						hostno,  message,   target);
#endif	
				}
			}
			break;

		default : 
			printk("scsi%d : unknown phase.\n", hostno); 
			st0x_aborted = DID_ERROR; 
		}	

#ifdef SLOW_HANDSHAKE
/*
 * I really don't care to deal with borken devices in each single 
 * byte transfer case (ie, message in, message out, status), so
 * I'll do the wait here if necessary.
 */
		if (borken)
			borken_wait();
#endif
 
		} /* if ends */
		} /* while ends */

#if (DEBUG & (PHASE_DATAIN | PHASE_DATAOUT | PHASE_EXIT))
	printk("scsi%d : Transfered %d bytes\n", hostno, transfered);
#endif

#if (DEBUG & PHASE_EXIT)
#if 0		/* Doesn't work for scatter / gather */
	printk("Buffer : \n");
	for (i = 0; i < 20; ++i) 
		printk ("%02x  ", ((unsigned char *) data)[i]);	/* WDE mod */
	printk("\n");
#endif
	printk("scsi%d : status = ", hostno);
        print_status(status);
	printk("message = %02x\n", message);
#endif


/* We shouldn't reach this until *after* BSY has been deasserted */
#ifdef notyet
	if (st0x_aborted) {
		if (STATUS & STAT_BSY) {	
			seagate_st0x_reset(NULL);
			st0x_aborted = DID_RESET;
		} 
		abort_confirm = 1;
	} 
#endif

#ifdef LINKED
else {
/*
 * Fix the message byte so that unsuspecting high level drivers don't 
 * puke when they see a LINKED COMMAND message in place of the COMMAND 
 * COMPLETE they may be expecting.  Shouldn't be necessary, but it's 
 * better to be on the safe side. 
 *
 * A non LINKED* message byte will indicate that the command completed, 
 * and we are now disconnected.
 */

		switch (message) {
		case LINKED_CMD_COMPLETE :
		case LINKED_FLG_CMD_COMPLETE : 
			message = COMMAND_COMPLETE;
			linked_target = current_target;
			linked_lun = current_lun;
			linked_connected = 1;
#if (DEBUG & DEBUG_LINKED)
			printk("scsi%d : keeping I_T_L nexus established for linked command.\n", 
				hostno);
#endif
/*
 * We also will need to adjust status to accomodate intermediate conditions.
 */
			if ((status == INTERMEDIATE_GOOD) ||
				(status == INTERMEDIATE_C_GOOD))
				status = GOOD;
			
			break;
/*
 * We should also handle what are "normal" termination messages 
 * here (ABORT, BUS_DEVICE_RESET?, and COMMAND_COMPLETE individually, 
 * and flake if things aren't right.
 */

		default :
#if (DEBUG & DEBUG_LINKED)
			printk("scsi%d : closing I_T_L nexus.\n", hostno);
#endif
			linked_connected = 0;
		}
	}
#endif /* LINKED */




	if (should_reconnect) {
#if (DEBUG & PHASE_RESELECT)
		printk("scsi%d : exiting seagate_st0x_queue_command() with reconnect enabled.\n",
			hostno);
#endif
		CONTROL = BASE_CMD | CMD_INTR ;
	} else 
		CONTROL = BASE_CMD;

	return retcode (st0x_aborted);
	}

int seagate_st0x_abort (Scsi_Cmnd * SCpnt, int code)
	{
	if (code)
		st0x_aborted = code;
	else
		st0x_aborted = DID_ABORT;

		return 0;
	}

/*
	the seagate_st0x_reset function resets the SCSI bus
*/
	
int seagate_st0x_reset (Scsi_Cmnd * SCpnt)
	{
	unsigned clock;
	/*
		No timeouts - this command is going to fail because 
		it was reset.
	*/

#ifdef DEBUG
	printk("In seagate_st0x_reset()\n");
#endif


	/* assert  RESET signal on SCSI bus.  */
		
	CONTROL = BASE_CMD  | CMD_RST;
	clock=jiffies+2;

	
	/* Wait.  */
	
	while (jiffies < clock);

	CONTROL = BASE_CMD;
	
	st0x_aborted = DID_RESET;

#ifdef DEBUG
	printk("SCSI bus reset.\n");
#endif
	if(SCpnt) SCpnt->flags |= NEEDS_JUMPSTART;
	return 0;
	}

#ifdef CONFIG_BLK_DEV_SD

#include <asm/segment.h>
#include "sd.h"
#include "scsi_ioctl.h"

int seagate_st0x_biosparam(int size, int dev, int* ip) {
  unsigned char buf[256 + sizeof(int) * 2], cmd[6], *data, *page;
  int *sizes, result, formatted_sectors, total_sectors;
  int cylinders, heads, sectors;

  Scsi_Device *disk;

  disk = rscsi_disks[MINOR(dev) >> 4].device;

/*
 * Only SCSI-I CCS drives and later implement the necessary mode sense 
 * pages.  
 */

  if (disk->scsi_level < 2) 
	return -1;

  sizes = (int *) buf;
  data = (unsigned char *) (sizes + 2);

  cmd[0] = MODE_SENSE;
  cmd[1] = (disk->lun << 5) & 0xe5;
  cmd[2] = 0x04; /* Read page 4, rigid disk geometry page current values */
  cmd[3] = 0;
  cmd[4] = 255;
  cmd[5] = 0;

/*
 * We are transfering 0 bytes in the out direction, and expect to get back
 * 24 bytes for each mode page.
 */

  sizes[0] = 0;
  sizes[1] = 256;

  memcpy (data, cmd, 6);

  if (!(result = kernel_scsi_ioctl (disk, SCSI_IOCTL_SEND_COMMAND, (void *) buf))) {
/*
 * The mode page lies beyond the MODE SENSE header, with length 4, and 
 * the BLOCK DESCRIPTOR, with length header[3].
 */

    page = data + 4 + data[3];
    heads = (int) page[5];
    cylinders = (page[2] << 16) | (page[3] << 8) | page[4];

    cmd[2] = 0x03; /* Read page 3, format page current values */
    memcpy (data, cmd, 6);

    if (!(result = kernel_scsi_ioctl (disk, SCSI_IOCTL_SEND_COMMAND, (void *) buf))) {
      page = data + 4 + data[3];
      sectors = (page[10] << 8) | page[11];	

	
/*
 * Get the total number of formatted sectors from the block descriptor, 
 * so we can tell how many are being used for alternates.  
 */

      formatted_sectors = (data[4 + 1] << 16) | (data[4 + 2] << 8) |
	data[4 + 3] ;

      total_sectors = (heads * cylinders * sectors);

/*
 * Adjust the real geometry by subtracting 
 * (spare sectors / (heads * tracks)) cylinders from the number of cylinders.
 *
 * It appears that the CE cylinder CAN be a partial cylinder.
 */

     
printk("scsi%d : heads = %d cylinders = %d sectors = %d total = %d formatted = %d\n",
    hostno, heads, cylinders, sectors, total_sectors, formatted_sectors);

      if (!heads || !sectors || !cylinders)
	result = -1;
      else
	cylinders -= ((total_sectors - formatted_sectors) / (heads * sectors));

/*
 * Now, we need to do a sanity check on the geometry to see if it is 
 * BIOS compatable.  The maximum BIOS geometry is 1024 cylinders * 
 * 256 heads * 64 sectors. 
 */

      if ((cylinders > 1024) || (sectors > 64)) 
	result = -1;
      else {
	ip[0] = heads;
	ip[1] = sectors;
	ip[2] = cylinders;
      }

/* 
 * There should be an alternate mapping for things the seagate doesn't
 * understand, but I couldn't say what it is with reasonable certainty.
 */

      }
    }
    
  return result;
}
#endif /* CONFIG_BLK_DEV_SD */

#endif	/* defined(CONFIG_SCSI_SEGATE) */