NCR5380.c

	 * 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 = (Scsi_Cmnd *) hostdata->issue_queue; tmp->host_scribble; tmp = (Scsi_Cmnd *) tmp->host_scribble);
		LIST(cmd, tmp);
		tmp->host_scribble = (unsigned char *) cmd;
	}
	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 */
	schedule_delayed_work(&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;
	Scsi_Cmnd *tmp, *prev;
	int done;
	
	spin_lock_irq(instance->host_lock);
	do {
		/* Lock held here */
		done = 1;
		if (!hostdata->connected && !hostdata->selecting) {
			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 = (Scsi_Cmnd *) hostdata->issue_queue, prev = NULL; tmp; prev = tmp, tmp = (Scsi_Cmnd *) tmp->host_scribble) 
			{
				if (prev != tmp)
					dprintk(NDEBUG_LISTS, ("MAIN tmp=%p   target=%d   busy=%d lun=%d\n", tmp, tmp->target, hostdata->busy[tmp->target], tmp->lun));
				/*  When we find one, remove it from the issue queue. */
				if (!(hostdata->busy[tmp->device->id] & (1 << tmp->device->lun))) {
					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 = (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 %d removed from issue_queue\n", instance->host_no, tmp->target, tmp->lun));
	
					/*
					 * A successful selection is defined as one that 
					 * leaves us with the command connected and 
					 * in hostdata->connected, OR has terminated the
					 * command.
					 *
					 * With successful commands, we fall through
					 * and see if we can do an information transfer,
					 * with failures we will restart.
					 */
					hostdata->selecting = NULL;
					/* RvC: have to preset this to indicate a new command is being performed */

					if (!NCR5380_select(instance, tmp,
							    /* 
							     * REQUEST SENSE commands are issued without tagged
							     * queueing, even on SCSI-II devices because the 
							     * contingent allegiance condition exists for the 
							     * entire unit.
							     */
							    (tmp->cmnd[0] == REQUEST_SENSE) ? TAG_NONE : TAG_NEXT)) {
						break;
					} else {
						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));
					}
					/* lock held here still */
				}	/* if target/lun is not busy */
			}	/* for */
			/* exited locked */
		}	/* if (!hostdata->connected) */
		if (hostdata->selecting) {
			tmp = (Scsi_Cmnd *) hostdata->selecting;
			/* Selection will drop and retake the lock */
			if (!NCR5380_select(instance, tmp, (tmp->cmnd[0] == REQUEST_SENSE) ? TAG_NONE : TAG_NEXT)) {
				/* Ok ?? */
			} else {
				/* RvC: device failed, so we wait a long time
				   this is needed for Mustek scanners, that
				   do not respond to commands immediately
				   after a scan */
				printk(KERN_DEBUG "scsi%d: device %d did not respond in time\n", instance->host_no, tmp->device->id);
				LIST(tmp, hostdata->issue_queue);
				tmp->host_scribble = (unsigned char *) hostdata->issue_queue;
				hostdata->issue_queue = tmp;
				NCR5380_set_timer(hostdata, USLEEP_WAITLONG);
			}
		}	/* if hostdata->selecting */
		if (hostdata->connected
#ifdef REAL_DMA
		    && !hostdata->dmalen
#endif
		    && (!hostdata->time_expires || time_before_eq(hostdata->time_expires, jiffies))
		    ) {
			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;
		} else
			break;
	} 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 irq, void *dev_id) 
{
	NCR5380_local_declare();
	struct Scsi_Host *instance = (struct Scsi_Host *)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", irq));

	do {
		done = 1;
		spin_lock_irqsave(instance->host_lock, flags);
		/* Look for pending interrupts */
		NCR5380_setup(instance);
		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 transfered;

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

					transfered = (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)
			schedule_delayed_work(&hostdata->coroutine, 0);
	} while (!done);
	return IRQ_HANDLED;
}

#endif 

/**
 *	collect_stats		-	collect stats on a scsi command
 *	@hostdata: adapter 
 *	@cmd: command being issued
 *
 *	Update the statistical data by parsing the command in question
 */
 
static void collect_stats(struct NCR5380_hostdata *hostdata, Scsi_Cmnd * cmd) 
{
#ifdef NCR5380_STATS
	switch (cmd->cmnd[0]) {
	case WRITE:
	case WRITE_6:
	case WRITE_10:
		hostdata->time_write[scmd_id(cmd)] += (jiffies - hostdata->timebase);
		hostdata->pendingw--;
		break;
	case READ:
	case READ_6:
	case READ_10:
		hostdata->time_read[scmd_id(cmd)] += (jiffies - hostdata->timebase);
		hostdata->pendingr--;
		break;
	}
#endif
}


/* 
 * Function : int NCR5380_select (struct Scsi_Host *instance, Scsi_Cmnd *cmd, 
 *      int tag);
 *
 * 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, tag - set to TAG_NEXT for 
 *      new tag, TAG_NONE for untagged queueing, otherwise set to the tag for 
 *      the command that is presently connected.
 * 
 * Returns : -1 if selection could not execute for some reason,
 *      0 if selection succeeded or failed because the target 
 *      did not respond.
 *
 * 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, Scsi_Cmnd * cmd, int tag) 
{
	NCR5380_local_declare();
	struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *) instance->hostdata;
	unsigned char tmp[3], phase;
	unsigned char *data;
	int len;
	unsigned long timeout;
	unsigned char value;
	int err;
	NCR5380_setup(instance);

	if (hostdata->selecting)
		goto part2;

	hostdata->restart_select = 0;

	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);
		goto failed;
	}

	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));
		goto failed;
	}
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_SEL);

	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));
		goto failed;
	}
	/* 
	 * Again, bus clear + bus settle time is 1.2us, however, this is 
	 * a minimum so we'll udelay ceil(1.2)
	 */

	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.
	 */

	timeout = jiffies + (250 * HZ / 1000);

	/* 
	 * XXX very interesting - we're seeing a bounce where the BSY we 
	 * asserted is being reflected / still asserted (propagation delay?)
	 * and it's detecting as true.  Sigh.
	 */

	hostdata->select_time = 0;	/* we count the clock ticks at which we polled */
	hostdata->selecting = cmd;

part2:
	/* RvC: here we enter after a sleeping period, or immediately after
	   execution of part 1
	   we poll only once ech clock tick */
	value = NCR5380_read(STATUS_REG) & (SR_BSY | SR_IO);

	if (!value && (hostdata->select_time < HZ/4)) {
		/* RvC: we still must wait for a device response */
		hostdata->select_time++;	/* after 25 ticks the device has failed */
		NCR5380_set_timer(hostdata, 1);
		return 0;	/* RvC: we return here with hostdata->selecting set,
				   to go to sleep */
	}

	hostdata->selecting = NULL;/* clear this pointer, because we passed the
					   waiting period */
	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;
	}
	/* 
	 * 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);

	if (!(NCR5380_read(STATUS_REG) & SR_BSY)) {
		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
		if (hostdata->targets_present & (1 << scmd_id(cmd))) {
			printk(KERN_DEBUG "scsi%d : weirdness\n", instance->host_no);
			if (hostdata->restart_select)
				printk(KERN_DEBUG "\trestart select\n");
			NCR5380_dprint(NDEBUG_SELECTION, instance);
			NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
			return -1;
		}
		cmd->result = DID_BAD_TARGET << 16;
		collect_stats(hostdata, cmd);
		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));
		NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
		return 0;
	}
	hostdata->targets_present |= (1 << scmd_id(cmd));

	/*
	 * 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);
		goto failed;
	}

	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 == SCSI_IRQ_NONE) ? 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);

	initialize_SCp(cmd);

	return 0;

	/* Selection failed */
failed:
	return -1;

}

/* 
 * 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 transfered 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) {
	NCR5380_local_declare();
	unsigned char p = *phase, tmp;
	int c = *count;
	unsigned char *d = *data;
	/*
	 *      RvC: some administrative data to process polling time
	 */
	int break_allowed = 0;
	struct NCR5380_hostdata *hostdata = (struct NCR5380_hostdata *) instance->hostdata;
	NCR5380_setup(instance);

	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));

	/* RvC: don't know if this is necessary, but other SCSI I/O is short
	 *      so breaks are not necessary there
	 */
	if ((p == PHASE_DATAIN) || (p == PHASE_DATAOUT)) {
		break_allowed = 1;
	}
	do {
		/* 
		 * Wait for assertion of REQ, after which the phase bits will be 
		 * valid 
		 */

		/* RvC: we simply poll once, after that we stop temporarily
		 *      and let the device buffer fill up
		 *      if breaking is not allowed, we keep polling as long as needed
		 */

		/* FIXME */
		while (!((tmp = NCR5380_read(STATUS_REG)) & SR_REQ) && !break_allowed);
		if (!(tmp & SR_REQ)) {
			/* timeout condition */
			NCR5380_set_timer(hostdata, USLEEP_SLEEP);
			break;
		}

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

		/* Check for phase mismatch */
		if ((tmp & 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);
		}

		/* FIXME - if this fails bus reset ?? */
		NCR5380_poll_politely(instance, STATUS_REG, SR_REQ, 0, 5*HZ);
		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);
	if (tmp & SR_REQ)
		*phase = tmp & PHASE_MASK;
	else
		*phase = PHASE_UNKNOWN;

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

/**
 *	do_reset	-	issue a reset command
 *	@host: adapter to reset
 *
 *	Issue a reset sequence to the NCR5380 and try and get the bus
 *	back into sane shape.
 *
 *	Locks: caller holds queue lock
 */
 
static void do_reset(struct Scsi_Host *host) {
	NCR5380_local_declare();
	NCR5380_setup(host);

	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(25);
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
}

/*
 * 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 *host) {
	NCR5380_local_declare();
	unsigned char *msgptr, phase, tmp;
	int len;
	int rc;
	NCR5380_setup(host);


	/* 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(host, 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(host, 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(host, &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 transfered 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) {
	NCR5380_local_declare();
	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;

	NCR5380_setup(instance);

	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_DMA_MODE | 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