drivers/scsi/NCR5380.c

/* 
 * NCR 5380 generic driver routines.  These should make it *trivial*
 *      to implement 5380 SCSI drivers under Linux with a non-trantor
 *      architecture.
 *
 *      Note that these routines also work with NR53c400 family chips.
 *
 * Copyright 1993, Drew Eckhardt
 *      Visionary Computing 
 *      (Unix and Linux consulting and custom programming)
 *      drew@colorado.edu
 *      +1 (303) 666-5836
 *
 * For more information, please consult 
 *
 * NCR 5380 Family
 * SCSI Protocol Controller
 * Databook
 *
 * NCR Microelectronics
 * 1635 Aeroplaza Drive
 * Colorado Springs, CO 80916
 * 1+ (719) 578-3400
 * 1+ (800) 334-5454
 */

/*
 * Revision 1.10 1998/9/2	Alan Cox
 *				(alan@lxorguk.ukuu.org.uk)
 * Fixed up the timer lockups reported so far. Things still suck. Looking 
 * forward to 2.3 and per device request queues. Then it'll be possible to
 * SMP thread this beast and improve life no end.
 
 * Revision 1.9  1997/7/27	Ronald van Cuijlenborg
 *				(ronald.van.cuijlenborg@tip.nl or nutty@dds.nl)
 * (hopefully) fixed and enhanced USLEEP
 * added support for DTC3181E card (for Mustek scanner)
 *

 * Revision 1.8			Ingmar Baumgart
 *				(ingmar@gonzo.schwaben.de)
 * added support for NCR53C400a card
 *

 * Revision 1.7  1996/3/2       Ray Van Tassle (rayvt@comm.mot.com)
 * added proc_info
 * added support needed for DTC 3180/3280
 * fixed a couple of bugs
 *

 * Revision 1.5  1994/01/19  09:14:57  drew
 * Fixed udelay() hack that was being used on DATAOUT phases
 * instead of a proper wait for the final handshake.
 *
 * Revision 1.4  1994/01/19  06:44:25  drew
 * *** empty log message ***
 *
 * Revision 1.3  1994/01/19  05:24:40  drew
 * Added support for TCR LAST_BYTE_SENT bit.
 *
 * Revision 1.2  1994/01/15  06:14:11  drew
 * REAL DMA support, bug fixes.
 *
 * Revision 1.1  1994/01/15  06:00:54  drew
 * Initial revision
 *
 */

/*
 * Further development / testing that should be done : 
 * 1.  Cleanup the NCR5380_transfer_dma function and DMA operation complete
 *     code so that everything does the same thing that's done at the 
 *     end of a pseudo-DMA read operation.
 *
 * 2.  Fix REAL_DMA (interrupt driven, polled works fine) -
 *     basically, transfer size needs to be reduced by one 
 *     and the last byte read as is done with PSEUDO_DMA.
 * 
 * 4.  Test SCSI-II tagged queueing (I have no devices which support 
 *      tagged queueing)
 */
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_transport_spi.h>

#if (NDEBUG & NDEBUG_LISTS)
#define LIST(x,y) {printk("LINE:%d   Adding %p to %p\n", __LINE__, (void*)(x), (void*)(y)); if ((x)==(y)) udelay(5); }
#define REMOVE(w,x,y,z) {printk("LINE:%d   Removing: %p->%p  %p->%p \n", __LINE__, (void*)(w), (void*)(x), (void*)(y), (void*)(z)); if ((x)==(y)) udelay(5); }
#else
#define LIST(x,y)
#define REMOVE(w,x,y,z)
#endif

#ifndef notyet
#undef REAL_DMA
#endif

#ifdef REAL_DMA_POLL
#undef READ_OVERRUNS
#define READ_OVERRUNS
#endif

#ifdef BOARD_REQUIRES_NO_DELAY
#define io_recovery_delay(x)
#else
#define io_recovery_delay(x)	udelay(x)
#endif

/*
 * Design
 *
 * This is a generic 5380 driver.  To use it on a different platform, 
 * one simply writes appropriate system specific macros (ie, data
 * transfer - some PC's will use the I/O bus, 68K's must use 
 * memory mapped) and drops this file in their 'C' wrapper.
 *
 * (Note from hch:  unfortunately it was not enough for the different
 * m68k folks and instead of improving this driver they copied it
 * and hacked it up for their needs.  As a consequence they lost
 * most updates to this driver.  Maybe someone will fix all these
 * drivers to use a common core one day..)
 *
 * As far as command queueing, two queues are maintained for 
 * each 5380 in the system - commands that haven't been issued yet,
 * and commands that are currently executing.  This means that an 
 * unlimited number of commands may be queued, letting 
 * more commands propagate from the higher driver levels giving higher 
 * throughput.  Note that both I_T_L and I_T_L_Q nexuses are supported, 
 * allowing multiple commands to propagate all the way to a SCSI-II device 
 * while a command is already executing.
 *
 *
 * Issues specific to the NCR5380 : 
 *
 * When used in a PIO or pseudo-dma mode, the NCR5380 is a braindead 
 * piece of hardware that requires you to sit in a loop polling for 
 * the REQ signal as long as you are connected.  Some devices are 
 * brain dead (ie, many TEXEL CD ROM drives) and won't disconnect 
 * while doing long seek operations. [...] These
 * broken devices are the exception rather than the rule and I'd rather
 * spend my time optimizing for the normal case.
 *
 * Architecture :
 *
 * At the heart of the design is a coroutine, NCR5380_main,
 * which is started from a workqueue for each NCR5380 host in the
 * system.  It attempts to establish I_T_L or I_T_L_Q nexuses by
 * removing the commands from the issue queue and calling
 * NCR5380_select() if a nexus is not established. 
 *
 * Once a nexus is established, the NCR5380_information_transfer()
 * phase goes through the various phases as instructed by the target.
 * if the target goes into MSG IN and sends a DISCONNECT message,
 * the command structure is placed into the per instance disconnected
 * queue, and NCR5380_main tries to find more work.  If the target is 
 * idle for too long, the system will try to sleep.
 *
 * If a command has disconnected, eventually an interrupt will trigger,
 * calling NCR5380_intr()  which will in turn call NCR5380_reselect
 * to reestablish a nexus.  This will run main if necessary.
 *
 * On command termination, the done function will be called as 
 * appropriate.
 *
 * SCSI pointers are maintained in the SCp field of SCSI command 
 * structures, being initialized after the command is connected
 * in NCR5380_select, and set as appropriate in NCR5380_information_transfer.
 * Note that in violation of the standard, an implicit SAVE POINTERS operation
 * is done, since some BROKEN disks fail to issue an explicit SAVE POINTERS.
 */

/*
 * Using this file :
 * This file a skeleton Linux SCSI driver for the NCR 5380 series
 * of chips.  To use it, you write an architecture specific functions 
 * and macros and include this file in your driver.
 *
 * These macros control options : 
 * AUTOPROBE_IRQ - if defined, the NCR5380_probe_irq() function will be 
 *      defined.
 * 
 * AUTOSENSE - if defined, REQUEST SENSE will be performed automatically
 *      for commands that return with a CHECK CONDITION status. 
 *
 * DIFFERENTIAL - if defined, NCR53c81 chips will use external differential
 *      transceivers. 
 *
 * DONT_USE_INTR - if defined, never use interrupts, even if we probe or
 *      override-configure an IRQ.
 *
 * PSEUDO_DMA - if defined, PSEUDO DMA is used during the data transfer phases.
 *
 * REAL_DMA - if defined, REAL DMA is used during the data transfer phases.
 *
 * REAL_DMA_POLL - if defined, REAL DMA is used but the driver doesn't
 *      rely on phase mismatch and EOP interrupts to determine end 
 *      of phase.
 *
 * UNSAFE - leave interrupts enabled during pseudo-DMA transfers.  You
 *          only really want to use this if you're having a problem with
 *          dropped characters during high speed communications, and even
 *          then, you're going to be better off twiddling with transfersize
 *          in the high level code.
 *
 * Defaults for these will be provided although the user may want to adjust 
 * these to allocate CPU resources to the SCSI driver or "real" code.
 * 
 * These macros MUST be defined :
 * 
 * NCR5380_read(register)  - read from the specified register
 *
 * NCR5380_write(register, value) - write to the specific register 
 *
 * NCR5380_implementation_fields  - additional fields needed for this 
 *      specific implementation of the NCR5380
 *
 * Either real DMA *or* pseudo DMA may be implemented
 * REAL functions : 
 * NCR5380_REAL_DMA should be defined if real DMA is to be used.
 * Note that the DMA setup functions should return the number of bytes 
 *      that they were able to program the controller for.
 *
 * Also note that generic i386/PC versions of these macros are 
 *      available as NCR5380_i386_dma_write_setup,
 *      NCR5380_i386_dma_read_setup, and NCR5380_i386_dma_residual.
 *
 * NCR5380_dma_write_setup(instance, src, count) - initialize
 * NCR5380_dma_read_setup(instance, dst, count) - initialize
 * NCR5380_dma_residual(instance); - residual count
 *
 * PSEUDO functions :
 * NCR5380_pwrite(instance, src, count)
 * NCR5380_pread(instance, dst, count);
 *
 * The generic driver is initialized by calling NCR5380_init(instance),
 * after setting the appropriate host specific fields and ID.  If the 
 * driver wishes to autoprobe for an IRQ line, the NCR5380_probe_irq(instance,
 * possible) function may be used.
 */

static int do_abort(struct Scsi_Host *);
static void do_reset(struct Scsi_Host *);

/*
 *	initialize_SCp		-	init the scsi pointer field
 *	@cmd: command block to set up
 *
 *	Set up the internal fields in the SCSI command.
 */

static inline void initialize_SCp(struct scsi_cmnd *cmd)
{
	/* 
	 * Initialize the Scsi Pointer field so that all of the commands in the 
	 * various queues are valid.
	 */

	if (scsi_bufflen(cmd)) {
		cmd->SCp.buffer = scsi_sglist(cmd);
		cmd->SCp.buffers_residual = scsi_sg_count(cmd) - 1;
		cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
		cmd->SCp.this_residual = cmd->SCp.buffer->length;
	} else {
		cmd->SCp.buffer = NULL;
		cmd->SCp.buffers_residual = 0;
		cmd->SCp.ptr = NULL;
		cmd->SCp.this_residual = 0;
	}
}

/**
 * NCR5380_poll_politely - wait for chip register value
 * @instance: controller to poll
 * @reg: 5380 register to poll
 * @bit: Bitmask to check
 * @val: Value required to exit
 * @wait: Time-out in jiffies
 *
 * Polls the chip in a reasonably efficient manner waiting for an
 * event to occur. After a short quick poll we begin to yield the CPU
 * (if possible). In irq contexts the time-out is arbitrarily limited.
 * Callers may hold locks as long as they are held in irq mode.
 *
 * Returns 0 if event occurred otherwise -ETIMEDOUT.
 */

static int NCR5380_poll_politely(struct Scsi_Host *instance,
                                 int reg, int bit, int val, int wait)
{
	struct NCR5380_hostdata *hostdata = shost_priv(instance);
	unsigned long deadline = jiffies + wait;
	unsigned long n;

	/* Busy-wait for up to 10 ms */
	n = min(10000U, jiffies_to_usecs(wait));
	n *= hostdata->accesses_per_ms;
	n /= 1000;
	do {
		if ((NCR5380_read(reg) & bit) == val)
			return 0;
		cpu_relax();
	} while (n--);

	if (irqs_disabled() || in_interrupt())
		return -ETIMEDOUT;

	/* Repeatedly sleep for 1 ms until deadline */
	while (time_is_after_jiffies(deadline)) {
		schedule_timeout_uninterruptible(1);
		if ((NCR5380_read(reg) & bit) == val)
			return 0;
	}

	return -ETIMEDOUT;
}

static struct {
	unsigned char value;
	const char *name;
} phases[] __maybe_unused = {
	{PHASE_DATAOUT, "DATAOUT"}, 
	{PHASE_DATAIN, "DATAIN"}, 
	{PHASE_CMDOUT, "CMDOUT"}, 
	{PHASE_STATIN, "STATIN"}, 
	{PHASE_MSGOUT, "MSGOUT"}, 
	{PHASE_MSGIN, "MSGIN"}, 
	{PHASE_UNKNOWN, "UNKNOWN"}
};

#if NDEBUG
static struct {
	unsigned char mask;
	const char *name;
} signals[] = { 
	{SR_DBP, "PARITY"}, 
	{SR_RST, "RST"}, 
	{SR_BSY, "BSY"}, 
	{SR_REQ, "REQ"}, 
	{SR_MSG, "MSG"}, 
	{SR_CD, "CD"}, 
	{SR_IO, "IO"}, 
	{SR_SEL, "SEL"}, 
	{0, NULL}
}, 
basrs[] = {
	{BASR_ATN, "ATN"}, 
	{BASR_ACK, "ACK"}, 
	{0, NULL}
}, 
icrs[] = { 
	{ICR_ASSERT_RST, "ASSERT RST"}, 
	{ICR_ASSERT_ACK, "ASSERT ACK"}, 
	{ICR_ASSERT_BSY, "ASSERT BSY"}, 
	{ICR_ASSERT_SEL, "ASSERT SEL"}, 
	{ICR_ASSERT_ATN, "ASSERT ATN"}, 
	{ICR_ASSERT_DATA, "ASSERT DATA"}, 
	{0, NULL}
}, 
mrs[] = { 
	{MR_BLOCK_DMA_MODE, "MODE BLOCK DMA"}, 
	{MR_TARGET, "MODE TARGET"}, 
	{MR_ENABLE_PAR_CHECK, "MODE PARITY CHECK"}, 
	{MR_ENABLE_PAR_INTR, "MODE PARITY INTR"}, 
	{MR_MONITOR_BSY, "MODE MONITOR BSY"}, 
	{MR_DMA_MODE, "MODE DMA"}, 
	{MR_ARBITRATE, "MODE ARBITRATION"}, 
	{0, NULL}
};

/**
 *	NCR5380_print	-	print scsi bus signals
 *	@instance:	adapter state to dump
 *
 *	Print the SCSI bus signals for debugging purposes
 *
 *	Locks: caller holds hostdata lock (not essential)
 */

static void NCR5380_print(struct Scsi_Host *instance)
{
	unsigned char status, data, basr, mr, icr, i;

	data = NCR5380_read(CURRENT_SCSI_DATA_REG);
	status = NCR5380_read(STATUS_REG);
	mr = NCR5380_read(MODE_REG);
	icr = NCR5380_read(INITIATOR_COMMAND_REG);
	basr = NCR5380_read(BUS_AND_STATUS_REG);

	printk("STATUS_REG: %02x ", status);
	for (i = 0; signals[i].mask; ++i)
		if (status & signals[i].mask)
			printk(",%s", signals[i].name);
	printk("\nBASR: %02x ", basr);
	for (i = 0; basrs[i].mask; ++i)
		if (basr & basrs[i].mask)
			printk(",%s", basrs[i].name);
	printk("\nICR: %02x ", icr);
	for (i = 0; icrs[i].mask; ++i)
		if (icr & icrs[i].mask)
			printk(",%s", icrs[i].name);
	printk("\nMODE: %02x ", mr);
	for (i = 0; mrs[i].mask; ++i)
		if (mr & mrs[i].mask)
			printk(",%s", mrs[i].name);
	printk("\n");
}


/* 
 *	NCR5380_print_phase	-	show SCSI phase
 *	@instance: adapter to dump
 *
 * 	Print the current SCSI phase for debugging purposes
 *
 *	Locks: none
 */

static void NCR5380_print_phase(struct Scsi_Host *instance)
{
	unsigned char status;
	int i;

	status = NCR5380_read(STATUS_REG);
	if (!(status & SR_REQ))
		printk("scsi%d : REQ not asserted, phase unknown.\n", instance->host_no);
	else {
		for (i = 0; (phases[i].value != PHASE_UNKNOWN) && (phases[i].value != (status & PHASE_MASK)); ++i);
		printk("scsi%d : phase %s\n", instance->host_no, phases[i].name);
	}
}
#endif


static int probe_irq __initdata;

/**
 *	probe_intr	-	helper for IRQ autoprobe
 *	@irq: interrupt number
 *	@dev_id: unused
 *	@regs: unused
 *
 *	Set a flag to indicate the IRQ in question was received. This is
 *	used by the IRQ probe code.
 */
 
static irqreturn_t __init probe_intr(int irq, void *dev_id)
{
	probe_irq = irq;
	return IRQ_HANDLED;
}

/**
 *	NCR5380_probe_irq	-	find the IRQ of an NCR5380
 *	@instance: NCR5380 controller
 *	@possible: bitmask of ISA IRQ lines
 *
 *	Autoprobe for the IRQ line used by the NCR5380 by triggering an IRQ
 *	and then looking to see what interrupt actually turned up.
 *
 *	Locks: none, irqs must be enabled on entry
 */

static int __init __maybe_unused NCR5380_probe_irq(struct Scsi_Host *instance,
						int possible)
{
	struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *) instance->hostdata;
	unsigned long timeout;
	int trying_irqs, i, mask;

	for (trying_irqs = 0, i = 1, mask = 2; i < 16; ++i, mask <<= 1)
		if ((mask & possible) && (request_irq(i, &probe_intr, 0, "NCR-probe", NULL) == 0))
			trying_irqs |= mask;

	timeout = jiffies + msecs_to_jiffies(250);
	probe_irq = NO_IRQ;

	/*
	 * A interrupt is triggered whenever BSY = false, SEL = true
	 * and a bit set in the SELECT_ENABLE_REG is asserted on the 
	 * SCSI bus.
	 *
	 * Note that the bus is only driven when the phase control signals
	 * (I/O, C/D, and MSG) match those in the TCR, so we must reset that
	 * to zero.
	 */

	NCR5380_write(TARGET_COMMAND_REG, 0);
	NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
	NCR5380_write(OUTPUT_DATA_REG, hostdata->id_mask);
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_DATA | ICR_ASSERT_SEL);

	while (probe_irq == NO_IRQ && time_before(jiffies, timeout))
		schedule_timeout_uninterruptible(1);
	
	NCR5380_write(SELECT_ENABLE_REG, 0);
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);

	for (i = 1, mask = 2; i < 16; ++i, mask <<= 1)
		if (trying_irqs & mask)
			free_irq(i, NULL);

	return probe_irq;
}

/**
 *	NCR58380_info - report driver and host information
 *	@instance: relevant scsi host instance
 *
 *	For use as the host template info() handler.
 *
 *	Locks: none
 */

static const char *NCR5380_info(struct Scsi_Host *instance)
{
	struct NCR5380_hostdata *hostdata = shost_priv(instance);

	return hostdata->info;
}

static void prepare_info(struct Scsi_Host *instance)
{
	struct NCR5380_hostdata *hostdata = shost_priv(instance);

	snprintf(hostdata->info, sizeof(hostdata->info),
	         "%s, io_port 0x%lx, n_io_port %d, "
	         "base 0x%lx, irq %d, "
	         "can_queue %d, cmd_per_lun %d, "
	         "sg_tablesize %d, this_id %d, "
	         "flags { %s%s%s%s}, "
	         "options { %s} ",
	         instance->hostt->name, instance->io_port, instance->n_io_port,
	         instance->base, instance->irq,
	         instance->can_queue, instance->cmd_per_lun,
	         instance->sg_tablesize, instance->this_id,
	         hostdata->flags & FLAG_NCR53C400     ? "NCR53C400 "     : "",
	         hostdata->flags & FLAG_DTC3181E      ? "DTC3181E "      : "",
	         hostdata->flags & FLAG_NO_PSEUDO_DMA ? "NO_PSEUDO_DMA " : "",
	         hostdata->flags & FLAG_TOSHIBA_DELAY ? "TOSHIBA_DELAY "  : "",
#ifdef AUTOPROBE_IRQ
	         "AUTOPROBE_IRQ "
#endif
#ifdef DIFFERENTIAL
	         "DIFFERENTIAL "
#endif
#ifdef REAL_DMA
	         "REAL_DMA "
#endif
#ifdef REAL_DMA_POLL
	         "REAL_DMA_POLL "
#endif
#ifdef PARITY
	         "PARITY "
#endif
#ifdef PSEUDO_DMA
	         "PSEUDO_DMA "
#endif
#ifdef UNSAFE
	         "UNSAFE "
#endif
	         "");
}

/**
 *	NCR5380_print_status 	-	dump controller info
 *	@instance: controller to dump
 *
 *	Print commands in the various queues, called from NCR5380_abort 
 *	and NCR5380_debug to aid debugging.
 *
 *	Locks: called functions disable irqs
 */

static void __maybe_unused NCR5380_print_status(struct Scsi_Host *instance)
{
	NCR5380_dprint(NDEBUG_ANY, instance);
	NCR5380_dprint_phase(NDEBUG_ANY, instance);
}

#ifdef PSEUDO_DMA
/******************************************/
/*
 * /proc/scsi/[dtc pas16 t128 generic]/[0-ASC_NUM_BOARD_SUPPORTED]
 *
 * *buffer: I/O buffer
 * **start: if inout == FALSE pointer into buffer where user read should start
 * offset: current offset
 * length: length of buffer
 * hostno: Scsi_Host host_no
 * inout: TRUE - user is writing; FALSE - user is reading
 *
 * Return the number of bytes read from or written
 */

static int __maybe_unused NCR5380_write_info(struct Scsi_Host *instance,
	char *buffer, int length)
{
	struct NCR5380_hostdata *hostdata = shost_priv(instance);

	hostdata->spin_max_r = 0;
	hostdata->spin_max_w = 0;
	return 0;
}
#endif

static
void lprint_Scsi_Cmnd(struct scsi_cmnd *cmd, struct seq_file *m);
static
void lprint_command(unsigned char *cmd, struct seq_file *m);
static
void lprint_opcode(int opcode, struct seq_file *m);

static int __maybe_unused NCR5380_show_info(struct seq_file *m,
	struct Scsi_Host *instance)
{
	struct NCR5380_hostdata *hostdata;
	struct scsi_cmnd *ptr;

	hostdata = (struct NCR5380_hostdata *) instance->hostdata;

#ifdef PSEUDO_DMA
	seq_printf(m, "Highwater I/O busy spin counts: write %d, read %d\n",
	        hostdata->spin_max_w, hostdata->spin_max_r);
#endif
	spin_lock_irq(instance->host_lock);
	if (!hostdata->connected)
		seq_printf(m, "scsi%d: no currently connected command\n", instance->host_no);
	else
		lprint_Scsi_Cmnd((struct scsi_cmnd *) hostdata->connected, m);
	seq_printf(m, "scsi%d: issue_queue\n", instance->host_no);
	for (ptr = (struct scsi_cmnd *) hostdata->issue_queue; ptr; ptr = (struct scsi_cmnd *) ptr->host_scribble)
		lprint_Scsi_Cmnd(ptr, m);

	seq_printf(m, "scsi%d: disconnected_queue\n", instance->host_no);
	for (ptr = (struct scsi_cmnd *) hostdata->disconnected_queue; ptr; ptr = (struct scsi_cmnd *) ptr->host_scribble)
		lprint_Scsi_Cmnd(ptr, m);
	spin_unlock_irq(instance->host_lock);
	return 0;
}

static void lprint_Scsi_Cmnd(struct scsi_cmnd *cmd, struct seq_file *m)
{
	seq_printf(m, "scsi%d : destination target %d, lun %llu\n", cmd->device->host->host_no, cmd->device->id, cmd->device->lun);
	seq_puts(m, "        command = ");
	lprint_command(cmd->cmnd, m);
}

static void lprint_command(unsigned char *command, struct seq_file *m)
{
	int i, s;
	lprint_opcode(command[0], m);
	for (i = 1, s = COMMAND_SIZE(command[0]); i < s; ++i)
		seq_printf(m, "%02x ", command[i]);
	seq_putc(m, '\n');
}

static void lprint_opcode(int opcode, struct seq_file *m)
{
	seq_printf(m, "%2d (0x%02x)", opcode, opcode);
}


/**
 *	NCR5380_init	-	initialise an NCR5380
 *	@instance: adapter to configure
 *	@flags: control flags
 *
 *	Initializes *instance and corresponding 5380 chip,
 *      with flags OR'd into the initial flags value.
 *
 *	Notes : I assume that the host, hostno, and id bits have been
 *      set correctly.  I don't care about the irq and other fields. 
 *
 *	Returns 0 for success
 *
 *	Locks: interrupts must be enabled when we are called 
 */

static int NCR5380_init(struct Scsi_Host *instance, int flags)
{
	int i;
	struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *) instance->hostdata;
	unsigned long deadline;

	if(in_interrupt())
		printk(KERN_ERR "NCR5380_init called with interrupts off!\n");

	hostdata->id_mask = 1 << instance->this_id;
	for (i = hostdata->id_mask; i <= 0x80; i <<= 1)
		if (i > hostdata->id_mask)
			hostdata->id_higher_mask |= i;
	for (i = 0; i < 8; ++i)
		hostdata->busy[i] = 0;
#ifdef REAL_DMA
	hostdata->dmalen = 0;
#endif
	hostdata->connected = NULL;
	hostdata->issue_queue = NULL;
	hostdata->disconnected_queue = NULL;
	
	INIT_DELAYED_WORK(&hostdata->coroutine, NCR5380_main);
	hostdata->work_q = alloc_workqueue("ncr5380_%d",
	                        WQ_UNBOUND | WQ_MEM_RECLAIM,
	                        1, instance->host_no);
	if (!hostdata->work_q)
		return -ENOMEM;

	/* The CHECK code seems to break the 53C400. Will check it later maybe */
	if (flags & FLAG_NCR53C400)
		hostdata->flags = FLAG_HAS_LAST_BYTE_SENT | flags;
	else
		hostdata->flags = FLAG_CHECK_LAST_BYTE_SENT | flags;

	hostdata->host = instance;

	prepare_info(instance);

	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
	NCR5380_write(MODE_REG, MR_BASE);
	NCR5380_write(TARGET_COMMAND_REG, 0);
	NCR5380_write(SELECT_ENABLE_REG, 0);

	/* Calibrate register polling loop */
	i = 0;
	deadline = jiffies + 1;
	do {
		cpu_relax();
	} while (time_is_after_jiffies(deadline));
	deadline += msecs_to_jiffies(256);
	do {
		NCR5380_read(STATUS_REG);
		++i;
		cpu_relax();
	} while (time_is_after_jiffies(deadline));
	hostdata->accesses_per_ms = i / 256;

	return 0;
}

/**
 * NCR5380_maybe_reset_bus - Detect and correct bus wedge problems.
 * @instance: adapter to check
 *
 * If the system crashed, it may have crashed with a connected target and
 * the SCSI bus busy. Check for BUS FREE phase. If not, try to abort the
 * currently established nexus, which we know nothing about. Failing that
 * do a bus reset.
 *
 * Note that a bus reset will cause the chip to assert IRQ.
 *
 * Returns 0 if successful, otherwise -ENXIO.
 */

static int NCR5380_maybe_reset_bus(struct Scsi_Host *instance)
{
	struct NCR5380_hostdata *hostdata = shost_priv(instance);
	int pass;

	for (pass = 1; (NCR5380_read(STATUS_REG) & SR_BSY) && pass <= 6; ++pass) {
		switch (pass) {
		case 1:
		case 3:
		case 5:
			shost_printk(KERN_ERR, instance, "SCSI bus busy, waiting up to five seconds\n");
			NCR5380_poll_politely(instance,
			                      STATUS_REG, SR_BSY, 0, 5 * HZ);
			break;
		case 2:
			shost_printk(KERN_ERR, instance, "bus busy, attempting abort\n");
			do_abort(instance);
			break;
		case 4:
			shost_printk(KERN_ERR, instance, "bus busy, attempting reset\n");
			do_reset(instance);
			/* Wait after a reset; the SCSI standard calls for
			 * 250ms, we wait 500ms to be on the safe side.
			 * But some Toshiba CD-ROMs need ten times that.
			 */
			if (hostdata->flags & FLAG_TOSHIBA_DELAY)
				msleep(2500);
			else
				msleep(500);
			break;
		case 6:
			shost_printk(KERN_ERR, instance, "bus locked solid\n");
			return -ENXIO;
		}
	}
	return 0;
}

/**
 *	NCR5380_exit	-	remove an NCR5380
 *	@instance: adapter to remove
 */

static void NCR5380_exit(struct Scsi_Host *instance)
{
	struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *) instance->hostdata;

	cancel_delayed_work_sync(&hostdata->coroutine);
	destroy_workqueue(hostdata->work_q);
}

/**
 * NCR5380_queue_command - queue a command
 * @instance: the relevant SCSI adapter
 * @cmd: SCSI command
 *
 * cmd is added to the per-instance issue queue, with minor
 * twiddling done to the host specific fields of cmd.  If the
 * main coroutine is not running, it is restarted.
 */

static int NCR5380_queue_command(struct Scsi_Host *instance,
                                 struct scsi_cmnd *cmd)
{
	struct NCR5380_hostdata *hostdata = shost_priv(instance);
	struct scsi_cmnd *tmp;
	unsigned long flags;

#if (NDEBUG & NDEBUG_NO_WRITE)
	switch (cmd->cmnd[0]) {
	case WRITE_6:
	case WRITE_10:
		printk("scsi%d : WRITE attempted with NO_WRITE debugging flag set\n", instance->host_no);
		cmd->result = (DID_ERROR << 16);
		cmd->scsi_done(cmd);
		return 0;
	}
#endif				/* (NDEBUG & NDEBUG_NO_WRITE) */

	/* 
	 * We use the host_scribble field as a pointer to the next command  
	 * in a queue 
	 */

	cmd->host_scribble = NULL;
	cmd->result = 0;

	spin_lock_irqsave(instance->host_lock, flags);

	/* 
	 * Insert the cmd into the issue queue. Note that REQUEST SENSE 
	 * commands are added to the head of the queue since any command will
	 * clear the contingent allegiance condition that exists and the 
	 * sense data is only guaranteed to be valid while the condition exists.
	 */

	if (!(hostdata->issue_queue) || (cmd->cmnd[0] == REQUEST_SENSE)) {
		LIST(cmd, hostdata->issue_queue);
		cmd->host_scribble = (unsigned char *) hostdata->issue_queue;
		hostdata->issue_queue = cmd;
	} else {
		for (tmp = (struct scsi_cmnd *) hostdata->issue_queue; tmp->host_scribble; tmp = (struct scsi_cmnd *) tmp->host_scribble);
		LIST(cmd, tmp);
		tmp->host_scribble = (unsigned char *) cmd;
	}
	spin_unlock_irqrestore(instance->host_lock, flags);

	dprintk(NDEBUG_QUEUES, "scsi%d : command added to %s of queue\n", instance->host_no, (cmd->cmnd[0] == REQUEST_SENSE) ? "head" : "tail");

	/* Run the coroutine if it isn't already running. */
	/* Kick off command processing */
	queue_delayed_work(hostdata->work_q, &hostdata->coroutine, 0);
	return 0;
}

/**
 *	NCR5380_main	-	NCR state machines
 *
 *	NCR5380_main is a coroutine that runs as long as more work can 
 *      be done on the NCR5380 host adapters in a system.  Both 
 *      NCR5380_queue_command() and NCR5380_intr() will try to start it 
 *      in case it is not running.
 * 
 *	Locks: called as its own thread with no locks held. Takes the
 *	host lock and called routines may take the isa dma lock.
 */

static void NCR5380_main(struct work_struct *work)
{
	struct NCR5380_hostdata *hostdata =
		container_of(work, struct NCR5380_hostdata, coroutine.work);
	struct Scsi_Host *instance = hostdata->host;
	struct scsi_cmnd *tmp, *prev;
	int done;
	
	spin_lock_irq(instance->host_lock);
	do {
		/* Lock held here */
		done = 1;
		if (!hostdata->connected) {
			dprintk(NDEBUG_MAIN, "scsi%d : not connected\n", instance->host_no);
			/*
			 * Search through the issue_queue for a command destined
			 * for a target that's not busy.
			 */
			for (tmp = (struct scsi_cmnd *) hostdata->issue_queue, prev = NULL; tmp; prev = tmp, tmp = (struct scsi_cmnd *) tmp->host_scribble)
			{
				if (prev != tmp)
				    dprintk(NDEBUG_LISTS, "MAIN tmp=%p   target=%d   busy=%d lun=%llu\n", tmp, tmp->device->id, hostdata->busy[tmp->device->id], tmp->device->lun);
				/*  When we find one, remove it from the issue queue. */
				if (!(hostdata->busy[tmp->device->id] &
				      (1 << (u8)(tmp->device->lun & 0xff)))) {
					if (prev) {
						REMOVE(prev, prev->host_scribble, tmp, tmp->host_scribble);
						prev->host_scribble = tmp->host_scribble;
					} else {
						REMOVE(-1, hostdata->issue_queue, tmp, tmp->host_scribble);
						hostdata->issue_queue = (struct scsi_cmnd *) tmp->host_scribble;
					}
					tmp->host_scribble = NULL;

					/* 
					 * Attempt to establish an I_T_L nexus here. 
					 * On success, instance->hostdata->connected is set.
					 * On failure, we must add the command back to the
					 *   issue queue so we can keep trying. 
					 */
					dprintk(NDEBUG_MAIN|NDEBUG_QUEUES, "scsi%d : main() : command for target %d lun %llu removed from issue_queue\n", instance->host_no, tmp->device->id, tmp->device->lun);
	
					/*
					 * REQUEST SENSE commands are issued without tagged
					 * queueing, even on SCSI-II devices because the
					 * contingent allegiance condition exists for the
					 * entire unit.
					 */

					if (!NCR5380_select(instance, tmp)) {
						/* OK or bad target */
					} else {
						/* Need to retry */
						LIST(tmp, hostdata->issue_queue);
						tmp->host_scribble = (unsigned char *) hostdata->issue_queue;
						hostdata->issue_queue = tmp;
						done = 0;
						dprintk(NDEBUG_MAIN|NDEBUG_QUEUES, "scsi%d : main(): select() failed, returned to issue_queue\n", instance->host_no);
					}
					if (hostdata->connected)
						break;
					/* lock held here still */
				}	/* if target/lun is not busy */
			}	/* for */
			/* exited locked */
		}	/* if (!hostdata->connected) */
		if (hostdata->connected
#ifdef REAL_DMA
		    && !hostdata->dmalen
#endif
		    ) {
			dprintk(NDEBUG_MAIN, "scsi%d : main() : performing information transfer\n", instance->host_no);
			NCR5380_information_transfer(instance);
			dprintk(NDEBUG_MAIN, "scsi%d : main() : done set false\n", instance->host_no);
			done = 0;
		}
	} while (!done);
	
	spin_unlock_irq(instance->host_lock);
}

#ifndef DONT_USE_INTR

/**
 * 	NCR5380_intr	-	generic NCR5380 irq handler
 *	@irq: interrupt number
 *	@dev_id: device info
 *
 *	Handle interrupts, reestablishing I_T_L or I_T_L_Q nexuses
 *      from the disconnected queue, and restarting NCR5380_main() 
 *      as required.
 *
 *	Locks: takes the needed instance locks
 */

static irqreturn_t NCR5380_intr(int dummy, void *dev_id)
{
	struct Scsi_Host *instance = dev_id;
	struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *) instance->hostdata;
	int done;
	unsigned char basr;
	unsigned long flags;

	dprintk(NDEBUG_INTR, "scsi : NCR5380 irq %d triggered\n",
		instance->irq);

	do {
		done = 1;
		spin_lock_irqsave(instance->host_lock, flags);
		/* Look for pending interrupts */
		basr = NCR5380_read(BUS_AND_STATUS_REG);
		/* XXX dispatch to appropriate routine if found and done=0 */
		if (basr & BASR_IRQ) {
			NCR5380_dprint(NDEBUG_INTR, instance);
			if ((NCR5380_read(STATUS_REG) & (SR_SEL | SR_IO)) == (SR_SEL | SR_IO)) {
				done = 0;
				dprintk(NDEBUG_INTR, "scsi%d : SEL interrupt\n", instance->host_no);
				NCR5380_reselect(instance);
				(void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
			} else if (basr & BASR_PARITY_ERROR) {
				dprintk(NDEBUG_INTR, "scsi%d : PARITY interrupt\n", instance->host_no);
				(void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
			} else if ((NCR5380_read(STATUS_REG) & SR_RST) == SR_RST) {
				dprintk(NDEBUG_INTR, "scsi%d : RESET interrupt\n", instance->host_no);
				(void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
			} else {
#if defined(REAL_DMA)
				/*
				 * We should only get PHASE MISMATCH and EOP interrupts
				 * if we have DMA enabled, so do a sanity check based on
				 * the current setting of the MODE register.
				 */

				if ((NCR5380_read(MODE_REG) & MR_DMA) && ((basr & BASR_END_DMA_TRANSFER) || !(basr & BASR_PHASE_MATCH))) {
					int transferred;

					if (!hostdata->connected)
						panic("scsi%d : received end of DMA interrupt with no connected cmd\n", instance->hostno);

					transferred = (hostdata->dmalen - NCR5380_dma_residual(instance));
					hostdata->connected->SCp.this_residual -= transferred;
					hostdata->connected->SCp.ptr += transferred;
					hostdata->dmalen = 0;

					(void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
							
					/* FIXME: we need to poll briefly then defer a workqueue task ! */
					NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG, BASR_ACK, 0, 2*HZ);

					NCR5380_write(MODE_REG, MR_BASE);
					NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
				}
#else
				dprintk(NDEBUG_INTR, "scsi : unknown interrupt, BASR 0x%X, MR 0x%X, SR 0x%x\n", basr, NCR5380_read(MODE_REG), NCR5380_read(STATUS_REG));
				(void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
#endif
			}
		}	/* if BASR_IRQ */
		spin_unlock_irqrestore(instance->host_lock, flags);
		if(!done)
			queue_delayed_work(hostdata->work_q,
			                   &hostdata->coroutine, 0);
	} while (!done);
	return IRQ_HANDLED;
}

#endif 

/* 
 * Function : int NCR5380_select(struct Scsi_Host *instance,
 *                               struct scsi_cmnd *cmd)
 *
 * Purpose : establishes I_T_L or I_T_L_Q nexus for new or existing command,
 *      including ARBITRATION, SELECTION, and initial message out for 
 *      IDENTIFY and queue messages. 
 *
 * Inputs : instance - instantiation of the 5380 driver on which this 
 *      target lives, cmd - SCSI command to execute.
 * 
 * Returns : -1 if selection failed but should be retried.
 *      0 if selection failed and should not be retried.
 *      0 if selection succeeded completely (hostdata->connected == cmd).
 *
 * Side effects : 
 *      If bus busy, arbitration failed, etc, NCR5380_select() will exit 
 *              with registers as they should have been on entry - ie
 *              SELECT_ENABLE will be set appropriately, the NCR5380
 *              will cease to drive any SCSI bus signals.
 *
 *      If successful : I_T_L or I_T_L_Q nexus will be established, 
 *              instance->connected will be set to cmd.  
 *              SELECT interrupt will be disabled.
 *
 *      If failed (no target) : cmd->scsi_done() will be called, and the 
 *              cmd->result host byte set to DID_BAD_TARGET.
 *
 *	Locks: caller holds hostdata lock in IRQ mode
 */
 
static int NCR5380_select(struct Scsi_Host *instance, struct scsi_cmnd *cmd)
{
	struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *) instance->hostdata;
	unsigned char tmp[3], phase;
	unsigned char *data;
	int len;
	int err;

	NCR5380_dprint(NDEBUG_ARBITRATION, instance);
	dprintk(NDEBUG_ARBITRATION, "scsi%d : starting arbitration, id = %d\n", instance->host_no, instance->this_id);

	/* 
	 * Set the phase bits to 0, otherwise the NCR5380 won't drive the 
	 * data bus during SELECTION.
	 */

	NCR5380_write(TARGET_COMMAND_REG, 0);

	/* 
	 * Start arbitration.
	 */

	NCR5380_write(OUTPUT_DATA_REG, hostdata->id_mask);
	NCR5380_write(MODE_REG, MR_ARBITRATE);


	/* We can be relaxed here, interrupts are on, we are
	   in workqueue context, the birds are singing in the trees */
	spin_unlock_irq(instance->host_lock);
	err = NCR5380_poll_politely(instance, INITIATOR_COMMAND_REG, ICR_ARBITRATION_PROGRESS, ICR_ARBITRATION_PROGRESS, 5*HZ);
	spin_lock_irq(instance->host_lock);
	if (err < 0) {
		printk(KERN_DEBUG "scsi: arbitration timeout at %d\n", __LINE__);
		NCR5380_write(MODE_REG, MR_BASE);
		NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
		return -1;
	}

	dprintk(NDEBUG_ARBITRATION, "scsi%d : arbitration complete\n", instance->host_no);

	/* 
	 * The arbitration delay is 2.2us, but this is a minimum and there is 
	 * no maximum so we can safely sleep for ceil(2.2) usecs to accommodate
	 * the integral nature of udelay().
	 *
	 */

	udelay(3);

	/* Check for lost arbitration */
	if ((NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST) || (NCR5380_read(CURRENT_SCSI_DATA_REG) & hostdata->id_higher_mask) || (NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST)) {
		NCR5380_write(MODE_REG, MR_BASE);
		dprintk(NDEBUG_ARBITRATION, "scsi%d : lost arbitration, deasserting MR_ARBITRATE\n", instance->host_no);
		return -1;
	}

	/* After/during arbitration, BSY should be asserted.
	 * IBM DPES-31080 Version S31Q works now
	 * Tnx to Thomas_Roesch@m2.maus.de for finding this! (Roman)
	 */
	NCR5380_write(INITIATOR_COMMAND_REG,
		      ICR_BASE | ICR_ASSERT_SEL | ICR_ASSERT_BSY);

	if (!(hostdata->flags & FLAG_DTC3181E) &&
	    /* RvC: DTC3181E has some trouble with this
	     *      so we simply removed it. Seems to work with
	     *      only Mustek scanner attached
	     */
	    (NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST)) {
		NCR5380_write(MODE_REG, MR_BASE);
		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
		dprintk(NDEBUG_ARBITRATION, "scsi%d : lost arbitration, deasserting ICR_ASSERT_SEL\n", instance->host_no);
		return -1;
	}
	/* 
	 * Again, bus clear + bus settle time is 1.2us, however, this is 
	 * a minimum so we'll udelay ceil(1.2)
	 */

	if (hostdata->flags & FLAG_TOSHIBA_DELAY)
		udelay(15);
	else
		udelay(2);

	dprintk(NDEBUG_ARBITRATION, "scsi%d : won arbitration\n", instance->host_no);

	/* 
	 * Now that we have won arbitration, start Selection process, asserting 
	 * the host and target ID's on the SCSI bus.
	 */

	NCR5380_write(OUTPUT_DATA_REG, (hostdata->id_mask | (1 << scmd_id(cmd))));

	/* 
	 * Raise ATN while SEL is true before BSY goes false from arbitration,
	 * since this is the only way to guarantee that we'll get a MESSAGE OUT
	 * phase immediately after selection.
	 */

	NCR5380_write(INITIATOR_COMMAND_REG, (ICR_BASE | ICR_ASSERT_BSY | ICR_ASSERT_DATA | ICR_ASSERT_ATN | ICR_ASSERT_SEL));
	NCR5380_write(MODE_REG, MR_BASE);

	/* 
	 * Reselect interrupts must be turned off prior to the dropping of BSY,
	 * otherwise we will trigger an interrupt.
	 */
	NCR5380_write(SELECT_ENABLE_REG, 0);

	/*
	 * The initiator shall then wait at least two deskew delays and release 
	 * the BSY signal.
	 */
	udelay(1);		/* wingel -- wait two bus deskew delay >2*45ns */

	/* Reset BSY */
	NCR5380_write(INITIATOR_COMMAND_REG, (ICR_BASE | ICR_ASSERT_DATA | ICR_ASSERT_ATN | ICR_ASSERT_SEL));

	/* 
	 * Something weird happens when we cease to drive BSY - looks
	 * like the board/chip is letting us do another read before the 
	 * appropriate propagation delay has expired, and we're confusing
	 * a BSY signal from ourselves as the target's response to SELECTION.
	 *
	 * A small delay (the 'C++' frontend breaks the pipeline with an
	 * unnecessary jump, making it work on my 386-33/Trantor T128, the
	 * tighter 'C' code breaks and requires this) solves the problem - 
	 * the 1 us delay is arbitrary, and only used because this delay will 
	 * be the same on other platforms and since it works here, it should 
	 * work there.
	 *
	 * wingel suggests that this could be due to failing to wait
	 * one deskew delay.
	 */

	udelay(1);

	dprintk(NDEBUG_SELECTION, "scsi%d : selecting target %d\n", instance->host_no, scmd_id(cmd));

	/* 
	 * The SCSI specification calls for a 250 ms timeout for the actual 
	 * selection.
	 */

	err = NCR5380_poll_politely(instance, STATUS_REG, SR_BSY, SR_BSY,
	                            msecs_to_jiffies(250));

	if ((NCR5380_read(STATUS_REG) & (SR_SEL | SR_IO)) == (SR_SEL | SR_IO)) {
		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
		NCR5380_reselect(instance);
		printk("scsi%d : reselection after won arbitration?\n", instance->host_no);
		NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
		return -1;
	}

	if (err < 0) {
		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
		cmd->result = DID_BAD_TARGET << 16;
		cmd->scsi_done(cmd);
		NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
		dprintk(NDEBUG_SELECTION, "scsi%d : target did not respond within 250ms\n",
		        instance->host_no);
		return 0;
	}

	/* 
	 * No less than two deskew delays after the initiator detects the 
	 * BSY signal is true, it shall release the SEL signal and may 
	 * change the DATA BUS.                                     -wingel
	 */

	udelay(1);

	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);

	/*
	 * Since we followed the SCSI spec, and raised ATN while SEL 
	 * was true but before BSY was false during selection, the information
	 * transfer phase should be a MESSAGE OUT phase so that we can send the
	 * IDENTIFY message.
	 * 
	 * If SCSI-II tagged queuing is enabled, we also send a SIMPLE_QUEUE_TAG
	 * message (2 bytes) with a tag ID that we increment with every command
	 * until it wraps back to 0.
	 *
	 * XXX - it turns out that there are some broken SCSI-II devices,
	 *       which claim to support tagged queuing but fail when more than
	 *       some number of commands are issued at once.
	 */

	/* Wait for start of REQ/ACK handshake */

	spin_unlock_irq(instance->host_lock);
	err = NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, SR_REQ, HZ);
	spin_lock_irq(instance->host_lock);
	
	if(err) {
		printk(KERN_ERR "scsi%d: timeout at NCR5380.c:%d\n", instance->host_no, __LINE__);
		NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
		return -1;
	}

	dprintk(NDEBUG_SELECTION, "scsi%d : target %d selected, going into MESSAGE OUT phase.\n", instance->host_no, cmd->device->id);
	tmp[0] = IDENTIFY(((instance->irq == NO_IRQ) ? 0 : 1), cmd->device->lun);

	len = 1;
	cmd->tag = 0;

	/* Send message(s) */
	data = tmp;
	phase = PHASE_MSGOUT;
	NCR5380_transfer_pio(instance, &phase, &len, &data);
	dprintk(NDEBUG_SELECTION, "scsi%d : nexus established.\n", instance->host_no);
	/* XXX need to handle errors here */
	hostdata->connected = cmd;
	hostdata->busy[cmd->device->id] |= (1 << (cmd->device->lun & 0xFF));

	initialize_SCp(cmd);

	return 0;
}

/* 
 * Function : int NCR5380_transfer_pio (struct Scsi_Host *instance, 
 *      unsigned char *phase, int *count, unsigned char **data)
 *
 * Purpose : transfers data in given phase using polled I/O
 *
 * Inputs : instance - instance of driver, *phase - pointer to 
 *      what phase is expected, *count - pointer to number of 
 *      bytes to transfer, **data - pointer to data pointer.
 * 
 * Returns : -1 when different phase is entered without transferring
 *      maximum number of bytes, 0 if all bytes or transferred or exit
 *      is in same phase.
 *
 *      Also, *phase, *count, *data are modified in place.
 *
 * XXX Note : handling for bus free may be useful.
 */

/*
 * Note : this code is not as quick as it could be, however it 
 * IS 100% reliable, and for the actual data transfer where speed
 * counts, we will always do a pseudo DMA or DMA transfer.
 */

static int NCR5380_transfer_pio(struct Scsi_Host *instance, unsigned char *phase, int *count, unsigned char **data) {
	unsigned char p = *phase, tmp;
	int c = *count;
	unsigned char *d = *data;

	if (!(p & SR_IO))
		dprintk(NDEBUG_PIO, "scsi%d : pio write %d bytes\n", instance->host_no, c);
	else
		dprintk(NDEBUG_PIO, "scsi%d : pio read %d bytes\n", instance->host_no, c);

	/* 
	 * The NCR5380 chip will only drive the SCSI bus when the 
	 * phase specified in the appropriate bits of the TARGET COMMAND
	 * REGISTER match the STATUS REGISTER
	 */

	 NCR5380_write(TARGET_COMMAND_REG, PHASE_SR_TO_TCR(p));

	do {
		/* 
		 * Wait for assertion of REQ, after which the phase bits will be 
		 * valid 
		 */

		if (NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, SR_REQ, HZ) < 0)
			break;

		dprintk(NDEBUG_HANDSHAKE, "scsi%d : REQ detected\n", instance->host_no);

		/* Check for phase mismatch */
		if ((NCR5380_read(STATUS_REG) & PHASE_MASK) != p) {
			dprintk(NDEBUG_HANDSHAKE, "scsi%d : phase mismatch\n", instance->host_no);
			NCR5380_dprint_phase(NDEBUG_HANDSHAKE, instance);
			break;
		}
		/* Do actual transfer from SCSI bus to / from memory */
		if (!(p & SR_IO))
			NCR5380_write(OUTPUT_DATA_REG, *d);
		else
			*d = NCR5380_read(CURRENT_SCSI_DATA_REG);

		++d;

		/* 
		 * The SCSI standard suggests that in MSGOUT phase, the initiator
		 * should drop ATN on the last byte of the message phase
		 * after REQ has been asserted for the handshake but before
		 * the initiator raises ACK.
		 */

		if (!(p & SR_IO)) {
			if (!((p & SR_MSG) && c > 1)) {
				NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_DATA);
				NCR5380_dprint(NDEBUG_PIO, instance);
				NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_DATA | ICR_ASSERT_ACK);
			} else {
				NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_DATA | ICR_ASSERT_ATN);
				NCR5380_dprint(NDEBUG_PIO, instance);
				NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_DATA | ICR_ASSERT_ATN | ICR_ASSERT_ACK);
			}
		} else {
			NCR5380_dprint(NDEBUG_PIO, instance);
			NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ACK);
		}

		if (NCR5380_poll_politely(instance,
		                          STATUS_REG, SR_REQ, 0, 5 * HZ) < 0)
			break;

		dprintk(NDEBUG_HANDSHAKE, "scsi%d : req false, handshake complete\n", instance->host_no);

/*
 * We have several special cases to consider during REQ/ACK handshaking : 
 * 1.  We were in MSGOUT phase, and we are on the last byte of the 
 *      message.  ATN must be dropped as ACK is dropped.
 *
 * 2.  We are in a MSGIN phase, and we are on the last byte of the  
 *      message.  We must exit with ACK asserted, so that the calling
 *      code may raise ATN before dropping ACK to reject the message.
 *
 * 3.  ACK and ATN are clear and the target may proceed as normal.
 */
		if (!(p == PHASE_MSGIN && c == 1)) {
			if (p == PHASE_MSGOUT && c > 1)
				NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);
			else
				NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
		}
	} while (--c);

	dprintk(NDEBUG_PIO, "scsi%d : residual %d\n", instance->host_no, c);

	*count = c;
	*data = d;
	tmp = NCR5380_read(STATUS_REG);
	/* The phase read from the bus is valid if either REQ is (already)
	 * asserted or if ACK hasn't been released yet. The latter applies if
	 * we're in MSG IN, DATA IN or STATUS and all bytes have been received.
	 */
	if ((tmp & SR_REQ) || ((tmp & SR_IO) && c == 0))
		*phase = tmp & PHASE_MASK;
	else
		*phase = PHASE_UNKNOWN;

	if (!c || (*phase == p))
		return 0;
	else
		return -1;
}

/**
 * do_reset - issue a reset command
 * @instance: adapter to reset
 *
 * Issue a reset sequence to the NCR5380 and try and get the bus
 * back into sane shape.
 *
 * This clears the reset interrupt flag because there may be no handler for
 * it. When the driver is initialized, the NCR5380_intr() handler has not yet
 * been installed. And when in EH we may have released the ST DMA interrupt.
 */
 
static void do_reset(struct Scsi_Host *instance)
{
	unsigned long flags;

	local_irq_save(flags);
	NCR5380_write(TARGET_COMMAND_REG,
	              PHASE_SR_TO_TCR(NCR5380_read(STATUS_REG) & PHASE_MASK));
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_RST);
	udelay(50);
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
	(void)NCR5380_read(RESET_PARITY_INTERRUPT_REG);
	local_irq_restore(flags);
}

/*
 * Function : do_abort (Scsi_Host *host)
 * 
 * Purpose : abort the currently established nexus.  Should only be 
 *      called from a routine which can drop into a 
 * 
 * Returns : 0 on success, -1 on failure.
 *
 * Locks: queue lock held by caller
 *	FIXME: sort this out and get new_eh running
 */

static int do_abort(struct Scsi_Host *instance)
{
	unsigned char *msgptr, phase, tmp;
	int len;
	int rc;

	/* Request message out phase */
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);

	/* 
	 * Wait for the target to indicate a valid phase by asserting 
	 * REQ.  Once this happens, we'll have either a MSGOUT phase 
	 * and can immediately send the ABORT message, or we'll have some 
	 * other phase and will have to source/sink data.
	 * 
	 * We really don't care what value was on the bus or what value
	 * the target sees, so we just handshake.
	 */

	rc = NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, SR_REQ, 60 * HZ);
	
	if(rc < 0)
		return -1;

	tmp = (unsigned char)rc;
	
	NCR5380_write(TARGET_COMMAND_REG, PHASE_SR_TO_TCR(tmp));

	if ((tmp & PHASE_MASK) != PHASE_MSGOUT) {
		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN | ICR_ASSERT_ACK);
		rc = NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, 0, 3 * HZ);
		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);
		if(rc == -1)
			return -1;
	}
	tmp = ABORT;
	msgptr = &tmp;
	len = 1;
	phase = PHASE_MSGOUT;
	NCR5380_transfer_pio(instance, &phase, &len, &msgptr);

	/*
	 * If we got here, and the command completed successfully,
	 * we're about to go into bus free state.
	 */

	return len ? -1 : 0;
}

#if defined(REAL_DMA) || defined(PSEUDO_DMA) || defined (REAL_DMA_POLL)
/* 
 * Function : int NCR5380_transfer_dma (struct Scsi_Host *instance, 
 *      unsigned char *phase, int *count, unsigned char **data)
 *
 * Purpose : transfers data in given phase using either real
 *      or pseudo DMA.
 *
 * Inputs : instance - instance of driver, *phase - pointer to 
 *      what phase is expected, *count - pointer to number of 
 *      bytes to transfer, **data - pointer to data pointer.
 * 
 * Returns : -1 when different phase is entered without transferring
 *      maximum number of bytes, 0 if all bytes or transferred or exit
 *      is in same phase.
 *
 *      Also, *phase, *count, *data are modified in place.
 *
 *	Locks: io_request lock held by caller
 */


static int NCR5380_transfer_dma(struct Scsi_Host *instance, unsigned char *phase, int *count, unsigned char **data) {
	register int c = *count;
	register unsigned char p = *phase;
	register unsigned char *d = *data;
	unsigned char tmp;
	int foo;
#if defined(REAL_DMA_POLL)
	int cnt, toPIO;
	unsigned char saved_data = 0, overrun = 0, residue;
#endif

	struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *) instance->hostdata;

	if ((tmp = (NCR5380_read(STATUS_REG) & PHASE_MASK)) != p) {
		*phase = tmp;
		return -1;
	}
#if defined(REAL_DMA) || defined(REAL_DMA_POLL)
#ifdef READ_OVERRUNS
	if (p & SR_IO) {
		c -= 2;
	}
#endif
	dprintk(NDEBUG_DMA, "scsi%d : initializing DMA channel %d for %s, %d bytes %s %0x\n", instance->host_no, instance->dma_channel, (p & SR_IO) ? "reading" : "writing", c, (p & SR_IO) ? "to" : "from", (unsigned) d);
	hostdata->dma_len = (p & SR_IO) ? NCR5380_dma_read_setup(instance, d, c) : NCR5380_dma_write_setup(instance, d, c);
#endif

	NCR5380_write(TARGET_COMMAND_REG, PHASE_SR_TO_TCR(p));

#ifdef REAL_DMA
	NCR5380_write(MODE_REG, MR_BASE | MR_DMA_MODE | MR_ENABLE_EOP_INTR | MR_MONITOR_BSY);
#elif defined(REAL_DMA_POLL)
	NCR5380_write(MODE_REG, MR_BASE | MR_DMA_MODE);
#else
	/*
	 * Note : on my sample board, watch-dog timeouts occurred when interrupts
	 * were not disabled for the duration of a single DMA transfer, from 
	 * before the setting of DMA mode to after transfer of the last byte.
	 */

#if defined(PSEUDO_DMA) && defined(UNSAFE)
	spin_unlock_irq(instance->host_lock);
#endif
	/* KLL May need eop and parity in 53c400 */
	if (hostdata->flags & FLAG_NCR53C400)
		NCR5380_write(MODE_REG, MR_BASE | MR_DMA_MODE |
				MR_ENABLE_PAR_CHECK | MR_ENABLE_PAR_INTR |
				MR_ENABLE_EOP_INTR | MR_MONITOR_BSY);
	else
		NCR5380_write(MODE_REG, MR_BASE | MR_DMA_MODE);
#endif				/* def REAL_DMA */

	dprintk(NDEBUG_DMA, "scsi%d : mode reg = 0x%X\n", instance->host_no, NCR5380_read(MODE_REG));

	/* 
	 *	On the PAS16 at least I/O recovery delays are not needed here.
	 *	Everyone else seems to want them.
	 */

	if (p & SR_IO) {
		io_recovery_delay(1);
		NCR5380_write(START_DMA_INITIATOR_RECEIVE_REG, 0);
	} else {
		io_recovery_delay(1);
		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_DATA);
		io_recovery_delay(1);
		NCR5380_write(START_DMA_SEND_REG, 0);
		io_recovery_delay(1);
	}

#if defined(REAL_DMA_POLL)
	do {
		tmp = NCR5380_read(BUS_AND_STATUS_REG);
	} while ((tmp & BASR_PHASE_MATCH) && !(tmp & (BASR_BUSY_ERROR | BASR_END_DMA_TRANSFER)));

/*
   At this point, either we've completed DMA, or we have a phase mismatch,
   or we've unexpectedly lost BUSY (which is a real error).

   For write DMAs, we want to wait until the last byte has been
   transferred out over the bus before we turn off DMA mode.  Alas, there
   seems to be no terribly good way of doing this on a 5380 under all
   conditions.  For non-scatter-gather operations, we can wait until REQ
   and ACK both go false, or until a phase mismatch occurs.  Gather-writes
   are nastier, since the device will be expecting more data than we
   are prepared to send it, and REQ will remain asserted.  On a 53C8[01] we
   could test LAST BIT SENT to assure transfer (I imagine this is precisely
   why this signal was added to the newer chips) but on the older 538[01]
   this signal does not exist.  The workaround for this lack is a watchdog;
   we bail out of the wait-loop after a modest amount of wait-time if
   the usual exit conditions are not met.  Not a terribly clean or
   correct solution :-%

   Reads are equally tricky due to a nasty characteristic of the NCR5380.
   If the chip is in DMA mode for an READ, it will respond to a target's
   REQ by latching the SCSI data into the INPUT DATA register and asserting
   ACK, even if it has _already_ been notified by the DMA controller that
   the current DMA transfer has completed!  If the NCR5380 is then taken
   out of DMA mode, this already-acknowledged byte is lost.

   This is not a problem for "one DMA transfer per command" reads, because
   the situation will never arise... either all of the data is DMA'ed
   properly, or the target switches to MESSAGE IN phase to signal a
   disconnection (either operation bringing the DMA to a clean halt).
   However, in order to handle scatter-reads, we must work around the
   problem.  The chosen fix is to DMA N-2 bytes, then check for the
   condition before taking the NCR5380 out of DMA mode.  One or two extra
   bytes are transferred via PIO as necessary to fill out the original
   request.
 */

	if (p & SR_IO) {
#ifdef READ_OVERRUNS
		udelay(10);
		if (((NCR5380_read(BUS_AND_STATUS_REG) & (BASR_PHASE_MATCH | BASR_ACK)) == (BASR_PHASE_MATCH | BASR_ACK))) {
			saved_data = NCR5380_read(INPUT_DATA_REGISTER);
			overrun = 1;
		}
#endif
	} else {
		int limit = 100;
		while (((tmp = NCR5380_read(BUS_AND_STATUS_REG)) & BASR_ACK) || (NCR5380_read(STATUS_REG) & SR_REQ)) {
			if (!(tmp & BASR_PHASE_MATCH))
				break;
			if (--limit < 0)
				break;
		}
	}

	dprintk(NDEBUG_DMA, "scsi%d : polled DMA transfer complete, basr 0x%X, sr 0x%X\n", instance->host_no, tmp, NCR5380_read(STATUS_REG));

	NCR5380_write(MODE_REG, MR_BASE);
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);

	residue = NCR5380_dma_residual(instance);
	c -= residue;
	*count -= c;
	*data += c;
	*phase = NCR5380_read(STATUS_REG) & PHASE_MASK;

#ifdef READ_OVERRUNS
	if (*phase == p && (p & SR_IO) && residue == 0) {
		if (overrun) {
			dprintk(NDEBUG_DMA, "Got an input overrun, using saved byte\n");
			**data = saved_data;
			*data += 1;
			*count -= 1;
			cnt = toPIO = 1;
		} else {
			printk("No overrun??\n");
			cnt = toPIO = 2;
		}
		dprintk(NDEBUG_DMA, "Doing %d-byte PIO to 0x%X\n", cnt, *data);
		NCR5380_transfer_pio(instance, phase, &cnt, data);
		*count -= toPIO - cnt;
	}
#endif

	dprintk(NDEBUG_DMA, "Return with data ptr = 0x%X, count %d, last 0x%X, next 0x%X\n", *data, *count, *(*data + *count - 1), *(*data + *count));
	return 0;

#elif defined(REAL_DMA)
	return 0;
#else				/* defined(REAL_DMA_POLL) */
	if (p & SR_IO) {
#ifdef DMA_WORKS_RIGHT
		foo = NCR5380_pread(instance, d, c);
#else
		int diff = 1;
		if (hostdata->flags & FLAG_NCR53C400) {
			diff = 0;
		}
		if (!(foo = NCR5380_pread(instance, d, c - diff))) {
			/*
			 * We can't disable DMA mode after successfully transferring 
			 * what we plan to be the last byte, since that would open up
			 * a race condition where if the target asserted REQ before 
			 * we got the DMA mode reset, the NCR5380 would have latched
			 * an additional byte into the INPUT DATA register and we'd
			 * have dropped it.
			 * 
			 * The workaround was to transfer one fewer bytes than we 
			 * intended to with the pseudo-DMA read function, wait for 
			 * the chip to latch the last byte, read it, and then disable
			 * pseudo-DMA mode.
			 * 
			 * After REQ is asserted, the NCR5380 asserts DRQ and ACK.
			 * REQ is deasserted when ACK is asserted, and not reasserted
			 * until ACK goes false.  Since the NCR5380 won't lower ACK
			 * until DACK is asserted, which won't happen unless we twiddle
			 * the DMA port or we take the NCR5380 out of DMA mode, we 
			 * can guarantee that we won't handshake another extra 
			 * byte.
			 */

			if (!(hostdata->flags & FLAG_NCR53C400)) {
				while (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_DRQ));
				/* Wait for clean handshake */
				while (NCR5380_read(STATUS_REG) & SR_REQ);
				d[c - 1] = NCR5380_read(INPUT_DATA_REG);
			}
		}
#endif
	} else {
#ifdef DMA_WORKS_RIGHT
		foo = NCR5380_pwrite(instance, d, c);
#else
		int timeout;
		dprintk(NDEBUG_C400_PWRITE, "About to pwrite %d bytes\n", c);
		if (!(foo = NCR5380_pwrite(instance, d, c))) {
			/*
			 * Wait for the last byte to be sent.  If REQ is being asserted for 
			 * the byte we're interested, we'll ACK it and it will go false.  
			 */
			if (!(hostdata->flags & FLAG_HAS_LAST_BYTE_SENT)) {
				timeout = 20000;
				while (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_DRQ) && (NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH));

				if (!timeout)
					dprintk(NDEBUG_LAST_BYTE_SENT, "scsi%d : timed out on last byte\n", instance->host_no);

				if (hostdata->flags & FLAG_CHECK_LAST_BYTE_SENT) {
					hostdata->flags &= ~FLAG_CHECK_LAST_BYTE_SENT;
					if (NCR5380_read(TARGET_COMMAND_REG) & TCR_LAST_BYTE_SENT) {
						hostdata->flags |= FLAG_HAS_LAST_BYTE_SENT;
						dprintk(NDEBUG_LAST_BYTE_SENT, "scsi%d : last byte sent works\n", instance->host_no);
					}
				}
			} else {
				dprintk(NDEBUG_C400_PWRITE, "Waiting for LASTBYTE\n");
				while (!(NCR5380_read(TARGET_COMMAND_REG) & TCR_LAST_BYTE_SENT));
				dprintk(NDEBUG_C400_PWRITE, "Got LASTBYTE\n");
			}
		}
#endif
	}
	NCR5380_write(MODE_REG, MR_BASE);
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);

	if ((!(p & SR_IO)) && (hostdata->flags & FLAG_NCR53C400)) {
		dprintk(NDEBUG_C400_PWRITE, "53C400w: Checking for IRQ\n");
		if (NCR5380_read(BUS_AND_STATUS_REG) & BASR_IRQ) {
			dprintk(NDEBUG_C400_PWRITE, "53C400w:    got it, reading reset interrupt reg\n");
			NCR5380_read(RESET_PARITY_INTERRUPT_REG);
		} else {
			printk("53C400w:    IRQ NOT THERE!\n");
		}
	}
	*data = d + c;
	*count = 0;
	*phase = NCR5380_read(STATUS_REG) & PHASE_MASK;
#if defined(PSEUDO_DMA) && defined(UNSAFE)
	spin_lock_irq(instance->host_lock);
#endif				/* defined(REAL_DMA_POLL) */
	return foo;
#endif				/* def REAL_DMA */
}
#endif				/* defined(REAL_DMA) | defined(PSEUDO_DMA) */

/*
 * Function : NCR5380_information_transfer (struct Scsi_Host *instance)
 *
 * Purpose : run through the various SCSI phases and do as the target 
 *      directs us to.  Operates on the currently connected command, 
 *      instance->connected.
 *
 * Inputs : instance, instance for which we are doing commands
 *
 * Side effects : SCSI things happen, the disconnected queue will be 
 *      modified if a command disconnects, *instance->connected will
 *      change.
 *
 * XXX Note : we need to watch for bus free or a reset condition here 
 *      to recover from an unexpected bus free condition.
 *
 * Locks: io_request_lock held by caller in IRQ mode
 */

static void NCR5380_information_transfer(struct Scsi_Host *instance) {
	struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *)instance->hostdata;
	unsigned char msgout = NOP;
	int sink = 0;
	int len;
#if defined(PSEUDO_DMA) || defined(REAL_DMA_POLL)
	int transfersize;
#endif
	unsigned char *data;
	unsigned char phase, tmp, extended_msg[10], old_phase = 0xff;
	struct scsi_cmnd *cmd = (struct scsi_cmnd *) hostdata->connected;

	while (1) {
		tmp = NCR5380_read(STATUS_REG);
		/* We only have a valid SCSI phase when REQ is asserted */
		if (tmp & SR_REQ) {
			phase = (tmp & PHASE_MASK);
			if (phase != old_phase) {
				old_phase = phase;
				NCR5380_dprint_phase(NDEBUG_INFORMATION, instance);
			}
			if (sink && (phase != PHASE_MSGOUT)) {
				NCR5380_write(TARGET_COMMAND_REG, PHASE_SR_TO_TCR(tmp));

				NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN | ICR_ASSERT_ACK);
				while (NCR5380_read(STATUS_REG) & SR_REQ);
				NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);
				sink = 0;
				continue;
			}
			switch (phase) {
			case PHASE_DATAIN:
			case PHASE_DATAOUT:
#if (NDEBUG & NDEBUG_NO_DATAOUT)
				printk("scsi%d : NDEBUG_NO_DATAOUT set, attempted DATAOUT aborted\n", instance->host_no);
				sink = 1;
				do_abort(instance);
				cmd->result = DID_ERROR << 16;
				cmd->scsi_done(cmd);
				return;
#endif
				/* 
				 * If there is no room left in the current buffer in the
				 * scatter-gather list, move onto the next one.
				 */

				if (!cmd->SCp.this_residual && cmd->SCp.buffers_residual) {
					++cmd->SCp.buffer;
					--cmd->SCp.buffers_residual;
					cmd->SCp.this_residual = cmd->SCp.buffer->length;
					cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
					dprintk(NDEBUG_INFORMATION, "scsi%d : %d bytes and %d buffers left\n", instance->host_no, cmd->SCp.this_residual, cmd->SCp.buffers_residual);
				}
				/*
				 * The preferred transfer method is going to be 
				 * PSEUDO-DMA for systems that are strictly PIO,
				 * since we can let the hardware do the handshaking.
				 *
				 * For this to work, we need to know the transfersize
				 * ahead of time, since the pseudo-DMA code will sit
				 * in an unconditional loop.
				 */

#if defined(PSEUDO_DMA) || defined(REAL_DMA_POLL)
				transfersize = 0;
				if (!cmd->device->borken &&
				    !(hostdata->flags & FLAG_NO_PSEUDO_DMA))
					transfersize = NCR5380_dma_xfer_len(instance, cmd, phase);

				if (transfersize) {
					len = transfersize;
					if (NCR5380_transfer_dma(instance, &phase, &len, (unsigned char **) &cmd->SCp.ptr)) {
						/*
						 * If the watchdog timer fires, all future accesses to this
						 * device will use the polled-IO.
						 */
						scmd_printk(KERN_INFO, cmd,
							    "switching to slow handshake\n");
						cmd->device->borken = 1;
						sink = 1;
						do_abort(instance);
						cmd->result = DID_ERROR << 16;
						cmd->scsi_done(cmd);
						/* XXX - need to source or sink data here, as appropriate */
					} else
						cmd->SCp.this_residual -= transfersize - len;
				} else
#endif				/* defined(PSEUDO_DMA) || defined(REAL_DMA_POLL) */
					NCR5380_transfer_pio(instance, &phase, (int *) &cmd->SCp.this_residual, (unsigned char **)
							     &cmd->SCp.ptr);
				break;
			case PHASE_MSGIN:
				len = 1;
				data = &tmp;
				NCR5380_transfer_pio(instance, &phase, &len, &data);
				cmd->SCp.Message = tmp;

				switch (tmp) {
				case ABORT:
				case COMMAND_COMPLETE:
					/* Accept message by clearing ACK */
					sink = 1;
					NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
					hostdata->connected = NULL;
					dprintk(NDEBUG_QUEUES, "scsi%d : command for target %d, lun %llu completed\n", instance->host_no, cmd->device->id, cmd->device->lun);
					hostdata->busy[cmd->device->id] &= ~(1 << (cmd->device->lun & 0xFF));

					/* 
					 * I'm not sure what the correct thing to do here is : 
					 * 
					 * If the command that just executed is NOT a request 
					 * sense, the obvious thing to do is to set the result
					 * code to the values of the stored parameters.
					 * 
					 * If it was a REQUEST SENSE command, we need some way 
					 * to differentiate between the failure code of the original
					 * and the failure code of the REQUEST sense - the obvious
					 * case is success, where we fall through and leave the result
					 * code unchanged.
					 * 
					 * The non-obvious place is where the REQUEST SENSE failed 
					 */

					if (cmd->cmnd[0] != REQUEST_SENSE)
						cmd->result = cmd->SCp.Status | (cmd->SCp.Message << 8);
					else if (status_byte(cmd->SCp.Status) != GOOD)
						cmd->result = (cmd->result & 0x00ffff) | (DID_ERROR << 16);

					if ((cmd->cmnd[0] == REQUEST_SENSE) &&
						hostdata->ses.cmd_len) {
						scsi_eh_restore_cmnd(cmd, &hostdata->ses);
						hostdata->ses.cmd_len = 0 ;
					}

					if ((cmd->cmnd[0] != REQUEST_SENSE) && (status_byte(cmd->SCp.Status) == CHECK_CONDITION)) {
						scsi_eh_prep_cmnd(cmd, &hostdata->ses, NULL, 0, ~0);

						dprintk(NDEBUG_AUTOSENSE, "scsi%d : performing request sense\n", instance->host_no);

						LIST(cmd, hostdata->issue_queue);
						cmd->host_scribble = (unsigned char *)
						    hostdata->issue_queue;
						hostdata->issue_queue = (struct scsi_cmnd *) cmd;
						dprintk(NDEBUG_QUEUES, "scsi%d : REQUEST SENSE added to head of issue queue\n", instance->host_no);
					} else {
						cmd->scsi_done(cmd);
					}

					NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
					/* 
					 * Restore phase bits to 0 so an interrupted selection, 
					 * arbitration can resume.
					 */
					NCR5380_write(TARGET_COMMAND_REG, 0);

					while ((NCR5380_read(STATUS_REG) & SR_BSY) && !hostdata->connected)
						barrier();
					return;
				case MESSAGE_REJECT:
					/* Accept message by clearing ACK */
					NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
					switch (hostdata->last_message) {
					case HEAD_OF_QUEUE_TAG:
					case ORDERED_QUEUE_TAG:
					case SIMPLE_QUEUE_TAG:
						cmd->device->simple_tags = 0;
						hostdata->busy[cmd->device->id] |= (1 << (cmd->device->lun & 0xFF));
						break;
					default:
						break;
					}
					break;
				case DISCONNECT:{
						/* Accept message by clearing ACK */
						NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
						LIST(cmd, hostdata->disconnected_queue);
						cmd->host_scribble = (unsigned char *)
						    hostdata->disconnected_queue;
						hostdata->connected = NULL;
						hostdata->disconnected_queue = cmd;
						dprintk(NDEBUG_QUEUES, "scsi%d : command for target %d lun %llu was moved from connected to" "  the disconnected_queue\n", instance->host_no, cmd->device->id, cmd->device->lun);
						/* 
						 * Restore phase bits to 0 so an interrupted selection, 
						 * arbitration can resume.
						 */
						NCR5380_write(TARGET_COMMAND_REG, 0);

						/* Enable reselect interrupts */
						NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
						/* Wait for bus free to avoid nasty timeouts - FIXME timeout !*/
						/* NCR538_poll_politely(instance, STATUS_REG, SR_BSY, 0, 30 * HZ); */
						while ((NCR5380_read(STATUS_REG) & SR_BSY) && !hostdata->connected)
							barrier();
						return;
					}
					/* 
					 * The SCSI data pointer is *IMPLICITLY* saved on a disconnect
					 * operation, in violation of the SCSI spec so we can safely 
					 * ignore SAVE/RESTORE pointers calls.
					 *
					 * Unfortunately, some disks violate the SCSI spec and 
					 * don't issue the required SAVE_POINTERS message before
					 * disconnecting, and we have to break spec to remain 
					 * compatible.
					 */
				case SAVE_POINTERS:
				case RESTORE_POINTERS:
					/* Accept message by clearing ACK */
					NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
					break;
				case EXTENDED_MESSAGE:
/* 
 * Extended messages are sent in the following format :
 * Byte         
 * 0            EXTENDED_MESSAGE == 1
 * 1            length (includes one byte for code, doesn't 
 *              include first two bytes)
 * 2            code
 * 3..length+1  arguments
 *
 * Start the extended message buffer with the EXTENDED_MESSAGE
 * byte, since spi_print_msg() wants the whole thing.  
 */
					extended_msg[0] = EXTENDED_MESSAGE;
					/* Accept first byte by clearing ACK */
					NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
					dprintk(NDEBUG_EXTENDED, "scsi%d : receiving extended message\n", instance->host_no);

					len = 2;
					data = extended_msg + 1;
					phase = PHASE_MSGIN;
					NCR5380_transfer_pio(instance, &phase, &len, &data);

					dprintk(NDEBUG_EXTENDED, "scsi%d : length=%d, code=0x%02x\n", instance->host_no, (int) extended_msg[1], (int) extended_msg[2]);

					if (!len && extended_msg[1] <= (sizeof(extended_msg) - 1)) {
						/* Accept third byte by clearing ACK */
						NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
						len = extended_msg[1] - 1;
						data = extended_msg + 3;
						phase = PHASE_MSGIN;

						NCR5380_transfer_pio(instance, &phase, &len, &data);
						dprintk(NDEBUG_EXTENDED, "scsi%d : message received, residual %d\n", instance->host_no, len);

						switch (extended_msg[2]) {
						case EXTENDED_SDTR:
						case EXTENDED_WDTR:
						case EXTENDED_MODIFY_DATA_POINTER:
						case EXTENDED_EXTENDED_IDENTIFY:
							tmp = 0;
						}
					} else if (len) {
						printk("scsi%d: error receiving extended message\n", instance->host_no);
						tmp = 0;
					} else {
						printk("scsi%d: extended message code %02x length %d is too long\n", instance->host_no, extended_msg[2], extended_msg[1]);
						tmp = 0;
					}
					/* Fall through to reject message */

					/* 
					 * If we get something weird that we aren't expecting, 
					 * reject it.
					 */
				default:
					if (!tmp) {
						printk("scsi%d: rejecting message ", instance->host_no);
						spi_print_msg(extended_msg);
						printk("\n");
					} else if (tmp != EXTENDED_MESSAGE)
						scmd_printk(KERN_INFO, cmd,
							"rejecting unknown message %02x\n",tmp);
					else
						scmd_printk(KERN_INFO, cmd,
							"rejecting unknown extended message code %02x, length %d\n", extended_msg[1], extended_msg[0]);

					msgout = MESSAGE_REJECT;
					NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);
					break;
				}	/* switch (tmp) */
				break;
			case PHASE_MSGOUT:
				len = 1;
				data = &msgout;
				hostdata->last_message = msgout;
				NCR5380_transfer_pio(instance, &phase, &len, &data);
				if (msgout == ABORT) {
					hostdata->busy[cmd->device->id] &= ~(1 << (cmd->device->lun & 0xFF));
					hostdata->connected = NULL;
					cmd->result = DID_ERROR << 16;
					cmd->scsi_done(cmd);
					NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
					return;
				}
				msgout = NOP;
				break;
			case PHASE_CMDOUT:
				len = cmd->cmd_len;
				data = cmd->cmnd;
				/* 
				 * XXX for performance reasons, on machines with a 
				 * PSEUDO-DMA architecture we should probably 
				 * use the dma transfer function.  
				 */
				NCR5380_transfer_pio(instance, &phase, &len, &data);
				break;
			case PHASE_STATIN:
				len = 1;
				data = &tmp;
				NCR5380_transfer_pio(instance, &phase, &len, &data);
				cmd->SCp.Status = tmp;
				break;
			default:
				printk("scsi%d : unknown phase\n", instance->host_no);
				NCR5380_dprint(NDEBUG_ANY, instance);
			}	/* switch(phase) */
		} else {
			spin_unlock_irq(instance->host_lock);
			NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, SR_REQ, HZ);
			spin_lock_irq(instance->host_lock);
		}
	}			/* while (1) */
}

/*
 * Function : void NCR5380_reselect (struct Scsi_Host *instance)
 *
 * Purpose : does reselection, initializing the instance->connected 
 *      field to point to the scsi_cmnd for which the I_T_L or I_T_L_Q
 *      nexus has been reestablished,
 *      
 * Inputs : instance - this instance of the NCR5380.
 *
 * Locks: io_request_lock held by caller if IRQ driven
 */

static void NCR5380_reselect(struct Scsi_Host *instance) {
	struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *)
	 instance->hostdata;
	unsigned char target_mask;
	unsigned char lun, phase;
	int len;
	unsigned char msg[3];
	unsigned char *data;
	struct scsi_cmnd *tmp = NULL, *prev;
	int abort = 0;

	/*
	 * Disable arbitration, etc. since the host adapter obviously
	 * lost, and tell an interrupted NCR5380_select() to restart.
	 */

	NCR5380_write(MODE_REG, MR_BASE);

	target_mask = NCR5380_read(CURRENT_SCSI_DATA_REG) & ~(hostdata->id_mask);
	dprintk(NDEBUG_SELECTION, "scsi%d : reselect\n", instance->host_no);

	/* 
	 * At this point, we have detected that our SCSI ID is on the bus,
	 * SEL is true and BSY was false for at least one bus settle delay
	 * (400 ns).
	 *
	 * We must assert BSY ourselves, until the target drops the SEL
	 * signal.
	 */

	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_BSY);

	/* FIXME: timeout too long, must fail to workqueue */	
	if(NCR5380_poll_politely(instance, STATUS_REG, SR_SEL, 0, 2*HZ)<0)
		abort = 1;
		
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);

	/*
	 * Wait for target to go into MSGIN.
	 * FIXME: timeout needed and fail to work queeu
	 */

	if(NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, SR_REQ, 2*HZ))
		abort = 1;

	len = 1;
	data = msg;
	phase = PHASE_MSGIN;
	NCR5380_transfer_pio(instance, &phase, &len, &data);

	if (!(msg[0] & 0x80)) {
		printk(KERN_ERR "scsi%d : expecting IDENTIFY message, got ", instance->host_no);
		spi_print_msg(msg);
		abort = 1;
	} else {
		/* Accept message by clearing ACK */
		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
		lun = (msg[0] & 0x07);

		/* 
		 * We need to add code for SCSI-II to track which devices have
		 * I_T_L_Q nexuses established, and which have simple I_T_L
		 * nexuses so we can chose to do additional data transfer.
		 */

		/* 
		 * Find the command corresponding to the I_T_L or I_T_L_Q  nexus we 
		 * just reestablished, and remove it from the disconnected queue.
		 */


		for (tmp = (struct scsi_cmnd *) hostdata->disconnected_queue, prev = NULL; tmp; prev = tmp, tmp = (struct scsi_cmnd *) tmp->host_scribble)
			if ((target_mask == (1 << tmp->device->id)) && (lun == (u8)tmp->device->lun)
			    ) {
				if (prev) {
					REMOVE(prev, prev->host_scribble, tmp, tmp->host_scribble);
					prev->host_scribble = tmp->host_scribble;
				} else {
					REMOVE(-1, hostdata->disconnected_queue, tmp, tmp->host_scribble);
					hostdata->disconnected_queue = (struct scsi_cmnd *) tmp->host_scribble;
				}
				tmp->host_scribble = NULL;
				break;
			}
		if (!tmp) {
			printk(KERN_ERR "scsi%d : warning : target bitmask %02x lun %d not in disconnect_queue.\n", instance->host_no, target_mask, lun);
			/* 
			 * Since we have an established nexus that we can't do anything with,
			 * we must abort it.  
			 */
			abort = 1;
		}
	}

	if (abort) {
		do_abort(instance);
	} else {
		hostdata->connected = tmp;
		dprintk(NDEBUG_RESELECTION, "scsi%d : nexus established, target = %d, lun = %llu, tag = %d\n", instance->host_no, tmp->device->id, tmp->device->lun, tmp->tag);
	}
}

/*
 * Function : void NCR5380_dma_complete (struct Scsi_Host *instance)
 *
 * Purpose : called by interrupt handler when DMA finishes or a phase
 *      mismatch occurs (which would finish the DMA transfer).  
 *
 * Inputs : instance - this instance of the NCR5380.
 *
 * Returns : pointer to the scsi_cmnd structure for which the I_T_L
 *      nexus has been reestablished, on failure NULL is returned.
 */

#ifdef REAL_DMA
static void NCR5380_dma_complete(NCR5380_instance * instance) {
	struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *) instance->hostdata;
	int transferred;

	/*
	 * XXX this might not be right.
	 *
	 * Wait for final byte to transfer, ie wait for ACK to go false.
	 *
	 * We should use the Last Byte Sent bit, unfortunately this is 
	 * not available on the 5380/5381 (only the various CMOS chips)
	 *
	 * FIXME: timeout, and need to handle long timeout/irq case
	 */

	NCR5380_poll_politely(instance, BUS_AND_STATUS_REG, BASR_ACK, 0, 5*HZ);

	NCR5380_write(MODE_REG, MR_BASE);
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);

	/*
	 * The only places we should see a phase mismatch and have to send
	 * data from the same set of pointers will be the data transfer
	 * phases.  So, residual, requested length are only important here.
	 */

	if (!(hostdata->connected->SCp.phase & SR_CD)) {
		transferred = instance->dmalen - NCR5380_dma_residual();
		hostdata->connected->SCp.this_residual -= transferred;
		hostdata->connected->SCp.ptr += transferred;
	}
}
#endif				/* def REAL_DMA */

/*
 * Function : int NCR5380_abort (struct scsi_cmnd *cmd)
 *
 * Purpose : abort a command
 *
 * Inputs : cmd - the scsi_cmnd to abort, code - code to set the
 *      host byte of the result field to, if zero DID_ABORTED is
 *      used.
 *
 * Returns : SUCCESS - success, FAILED on failure.
 *
 *	XXX - there is no way to abort the command that is currently
 *	connected, you have to wait for it to complete.  If this is
 *	a problem, we could implement longjmp() / setjmp(), setjmp()
 *	called where the loop started in NCR5380_main().
 *
 * Locks: host lock taken by caller
 */

static int NCR5380_abort(struct scsi_cmnd *cmd)
{
	struct Scsi_Host *instance = cmd->device->host;
	struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *) instance->hostdata;
	struct scsi_cmnd *tmp, **prev;

	scmd_printk(KERN_WARNING, cmd, "aborting command\n");

	spin_lock_irq(instance->host_lock);
	NCR5380_print_status(instance);

	dprintk(NDEBUG_ABORT, "scsi%d : abort called\n", instance->host_no);
	dprintk(NDEBUG_ABORT, "        basr 0x%X, sr 0x%X\n", NCR5380_read(BUS_AND_STATUS_REG), NCR5380_read(STATUS_REG));

#if 0
/*
 * Case 1 : If the command is the currently executing command, 
 * we'll set the aborted flag and return control so that 
 * information transfer routine can exit cleanly.
 */

	if (hostdata->connected == cmd) {
		dprintk(NDEBUG_ABORT, "scsi%d : aborting connected command\n", instance->host_no);
/*
 * We should perform BSY checking, and make sure we haven't slipped
 * into BUS FREE.
 */

		NCR5380_write(INITIATOR_COMMAND_REG, ICR_ASSERT_ATN);
/* 
 * Since we can't change phases until we've completed the current 
 * handshake, we have to source or sink a byte of data if the current
 * phase is not MSGOUT.
 */

/* 
 * Return control to the executing NCR drive so we can clear the
 * aborted flag and get back into our main loop.
 */

		return SUCCESS;
	}
#endif

/* 
 * Case 2 : If the command hasn't been issued yet, we simply remove it 
 *          from the issue queue.
 */
 
	dprintk(NDEBUG_ABORT, "scsi%d : abort going into loop.\n", instance->host_no);
	for (prev = (struct scsi_cmnd **) &(hostdata->issue_queue), tmp = (struct scsi_cmnd *) hostdata->issue_queue; tmp; prev = (struct scsi_cmnd **) &(tmp->host_scribble), tmp = (struct scsi_cmnd *) tmp->host_scribble)
		if (cmd == tmp) {
			REMOVE(5, *prev, tmp, tmp->host_scribble);
			(*prev) = (struct scsi_cmnd *) tmp->host_scribble;
			tmp->host_scribble = NULL;
			spin_unlock_irq(instance->host_lock);
			tmp->result = DID_ABORT << 16;
			dprintk(NDEBUG_ABORT, "scsi%d : abort removed command from issue queue.\n", instance->host_no);
			tmp->scsi_done(tmp);
			return SUCCESS;
		}
#if (NDEBUG  & NDEBUG_ABORT)
	/* KLL */
		else if (prev == tmp)
			printk(KERN_ERR "scsi%d : LOOP\n", instance->host_no);
#endif

/* 
 * Case 3 : If any commands are connected, we're going to fail the abort
 *          and let the high level SCSI driver retry at a later time or 
 *          issue a reset.
 *
 *          Timeouts, and therefore aborted commands, will be highly unlikely
 *          and handling them cleanly in this situation would make the common
 *          case of noresets less efficient, and would pollute our code.  So,
 *          we fail.
 */

	if (hostdata->connected) {
		spin_unlock_irq(instance->host_lock);
		dprintk(NDEBUG_ABORT, "scsi%d : abort failed, command connected.\n", instance->host_no);
		return FAILED;
	}
/*
 * Case 4: If the command is currently disconnected from the bus, and 
 *      there are no connected commands, we reconnect the I_T_L or 
 *      I_T_L_Q nexus associated with it, go into message out, and send 
 *      an abort message.
 *
 * This case is especially ugly. In order to reestablish the nexus, we
 * need to call NCR5380_select().  The easiest way to implement this 
 * function was to abort if the bus was busy, and let the interrupt
 * handler triggered on the SEL for reselect take care of lost arbitrations
 * where necessary, meaning interrupts need to be enabled.
 *
 * When interrupts are enabled, the queues may change - so we 
 * can't remove it from the disconnected queue before selecting it
 * because that could cause a failure in hashing the nexus if that 
 * device reselected.
 * 
 * Since the queues may change, we can't use the pointers from when we
 * first locate it.
 *
 * So, we must first locate the command, and if NCR5380_select()
 * succeeds, then issue the abort, relocate the command and remove
 * it from the disconnected queue.
 */

	for (tmp = (struct scsi_cmnd *) hostdata->disconnected_queue; tmp; tmp = (struct scsi_cmnd *) tmp->host_scribble)
		if (cmd == tmp) {
			dprintk(NDEBUG_ABORT, "scsi%d : aborting disconnected command.\n", instance->host_no);

			if (NCR5380_select(instance, cmd)) {
				spin_unlock_irq(instance->host_lock);
				return FAILED;
			}
			dprintk(NDEBUG_ABORT, "scsi%d : nexus reestablished.\n", instance->host_no);

			do_abort(instance);

			for (prev = (struct scsi_cmnd **) &(hostdata->disconnected_queue), tmp = (struct scsi_cmnd *) hostdata->disconnected_queue; tmp; prev = (struct scsi_cmnd **) &(tmp->host_scribble), tmp = (struct scsi_cmnd *) tmp->host_scribble)
				if (cmd == tmp) {
					REMOVE(5, *prev, tmp, tmp->host_scribble);
					*prev = (struct scsi_cmnd *) tmp->host_scribble;
					tmp->host_scribble = NULL;
					spin_unlock_irq(instance->host_lock);
					tmp->result = DID_ABORT << 16;
					tmp->scsi_done(tmp);
					return SUCCESS;
				}
		}
/*
 * Case 5 : If we reached this point, the command was not found in any of 
 *          the queues.
 *
 * We probably reached this point because of an unlikely race condition
 * between the command completing successfully and the abortion code,
 * so we won't panic, but we will notify the user in case something really
 * broke.
 */
	spin_unlock_irq(instance->host_lock);
	printk(KERN_WARNING "scsi%d : warning : SCSI command probably completed successfully\n"
			"         before abortion\n", instance->host_no);
	return FAILED;
}


/**
 * NCR5380_bus_reset - reset the SCSI bus
 * @cmd: SCSI command undergoing EH
 *
 * Returns SUCCESS
 */

static int NCR5380_bus_reset(struct scsi_cmnd *cmd)
{
	struct Scsi_Host *instance = cmd->device->host;

	spin_lock_irq(instance->host_lock);

#if (NDEBUG & NDEBUG_ANY)
	scmd_printk(KERN_INFO, cmd, "performing bus reset\n");
	NCR5380_print_status(instance);
#endif

	do_reset(instance);

	spin_unlock_irq(instance->host_lock);

	return SUCCESS;
}