/*
 *	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--;