atari_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.
     */

    local_irq_save(flags);
    /* ++guenther: now that the issue queue is being set up, we can lock ST-DMA.
     * Otherwise a running NCR5380_main may steal the lock.
     * Lock before actually inserting due to fairness reasons explained in
     * atari_scsi.c. If we insert first, then it's impossible for this driver
     * to release the lock.
     * Stop timer for this command while waiting for the lock, or timeouts
     * may happen (and they really do), and it's no good if the command doesn't
     * appear in any of the queues.
     * ++roman: Just disabling the NCR interrupt isn't sufficient here,
     * because also a timer int can trigger an abort or reset, which would
     * alter queues and touch the lock.
     */
    if (!IS_A_TT()) {
	oldto = atari_scsi_update_timeout(cmd, 0);
	falcon_get_lock();
	atari_scsi_update_timeout(cmd, oldto);
    }
    if (!(hostdata->issue_queue) || (cmd->cmnd[0] == REQUEST_SENSE)) {
	LIST(cmd, hostdata->issue_queue);
	NEXT(cmd) = hostdata->issue_queue;
	hostdata->issue_queue = cmd;
    } else {
	for (tmp = (Scsi_Cmnd *)hostdata->issue_queue;
	     NEXT(tmp); tmp = NEXT(tmp))
	    ;
	LIST(cmd, tmp);
	NEXT(tmp) = cmd;
    }
    local_irq_restore(flags);

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

    /* If queue_command() is called from an interrupt (real one or bottom
     * half), we let queue_main() do the job of taking care about main. If it
     * is already running, this is a no-op, else main will be queued.
     *
     * If we're not in an interrupt, we can call NCR5380_main()
     * unconditionally, because it cannot be already running.
     */
    if (in_interrupt() || ((flags >> 8) & 7) >= 6)
	queue_main();
    else
	NCR5380_main(NULL);
    return 0;
}

/*
 * Function : NCR5380_main (void) 
 *
 * Purpose : 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.
 * 
 * NOTE : NCR5380_main exits with interrupts *disabled*, the caller should 
 *  reenable them.  This prevents reentrancy and kernel stack overflow.
 */ 	
    
static void NCR5380_main (void *bl)
{
    Scsi_Cmnd *tmp, *prev;
    struct Scsi_Host *instance = first_instance;
    struct NCR5380_hostdata *hostdata = HOSTDATA(instance);
    int done;
    unsigned long flags;
    
    /*
     * We run (with interrupts disabled) until we're sure that none of 
     * the host adapters have anything that can be done, at which point 
     * we set main_running to 0 and exit.
     *
     * Interrupts are enabled before doing various other internal 
     * instructions, after we've decided that we need to run through
     * the loop again.
     *
     * this should prevent any race conditions.
     * 
     * ++roman: Just disabling the NCR interrupt isn't sufficient here,
     * because also a timer int can trigger an abort or reset, which can
     * alter queues and touch the Falcon lock.
     */

    /* Tell int handlers main() is now already executing.  Note that
       no races are possible here. If an int comes in before
       'main_running' is set here, and queues/executes main via the
       task queue, it doesn't do any harm, just this instance of main
       won't find any work left to do. */
    if (main_running)
    	return;
    main_running = 1;

    local_save_flags(flags);
    do {
	local_irq_disable(); /* Freeze request queues */
	done = 1;
	
	if (!hostdata->connected) {
	    MAIN_PRINTK( "scsi%d: not connected\n", HOSTNO );
	    /*
	     * Search through the issue_queue for a command destined
	     * for a target that's not busy.
	     */
#if (NDEBUG & NDEBUG_LISTS)
	    for (tmp = (Scsi_Cmnd *) hostdata->issue_queue, prev = NULL;
		 tmp && (tmp != prev); prev = tmp, tmp = NEXT(tmp))
		;
		/*printk("%p  ", tmp);*/
	    if ((tmp == prev) && tmp) printk(" LOOP\n");/* else printk("\n");*/
#endif
	    for (tmp = (Scsi_Cmnd *) hostdata->issue_queue, 
		 prev = NULL; tmp; prev = tmp, tmp = NEXT(tmp) ) {

#if (NDEBUG & NDEBUG_LISTS)
		if (prev != tmp)
		    printk("MAIN tmp=%p   target=%d   busy=%d lun=%d\n",
			   tmp, tmp->device->id, hostdata->busy[tmp->device->id],
			   tmp->device->lun);
#endif
		/*  When we find one, remove it from the issue queue. */
		/* ++guenther: possible race with Falcon locking */
		if (
#ifdef SUPPORT_TAGS
		    !is_lun_busy( tmp, tmp->cmnd[0] != REQUEST_SENSE)
#else
		    !(hostdata->busy[tmp->device->id] & (1 << tmp->device->lun))
#endif
		    ) {
		    /* ++guenther: just to be sure, this must be atomic */
		    local_irq_disable();
		    if (prev) {
		        REMOVE(prev, NEXT(prev), tmp, NEXT(tmp));
			NEXT(prev) = NEXT(tmp);
		    } else {
		        REMOVE(-1, hostdata->issue_queue, tmp, NEXT(tmp));
			hostdata->issue_queue = NEXT(tmp);
		    }
		    NEXT(tmp) = NULL;
		    falcon_dont_release++;
		    
		    /* reenable interrupts after finding one */
		    local_irq_restore(flags);
		    
		    /* 
		     * 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.	
		     */
		    MAIN_PRINTK("scsi%d: main(): command for target %d "
				"lun %d removed from issue_queue\n",
				HOSTNO, 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.
		     */
		    /* ++roman: ...and the standard also requires that
		     * REQUEST SENSE command are untagged.
		     */
		    
#ifdef SUPPORT_TAGS
		    cmd_get_tag( tmp, tmp->cmnd[0] != REQUEST_SENSE );
#endif
		    if (!NCR5380_select(instance, tmp, 
			    (tmp->cmnd[0] == REQUEST_SENSE) ? TAG_NONE : 
			    TAG_NEXT)) {
			falcon_dont_release--;
			/* release if target did not response! */
			falcon_release_lock_if_possible( hostdata );
			break;
		    } else {
			local_irq_disable();
			LIST(tmp, hostdata->issue_queue);
			NEXT(tmp) = hostdata->issue_queue;
			hostdata->issue_queue = tmp;
#ifdef SUPPORT_TAGS
			cmd_free_tag( tmp );
#endif
			falcon_dont_release--;
			local_irq_restore(flags);
			MAIN_PRINTK("scsi%d: main(): select() failed, "
				    "returned to issue_queue\n", HOSTNO);
			if (hostdata->connected)
			    break;
		    }
		} /* if target/lun/target queue is not busy */
	    } /* for issue_queue */
	} /* if (!hostdata->connected) */
		
	if (hostdata->connected 
#ifdef REAL_DMA
	    && !hostdata->dma_len
#endif
	    ) {
	    local_irq_restore(flags);
	    MAIN_PRINTK("scsi%d: main: performing information transfer\n",
			HOSTNO);
	    NCR5380_information_transfer(instance);
	    MAIN_PRINTK("scsi%d: main: done set false\n", HOSTNO);
	    done = 0;
	}
    } while (!done);

    /* Better allow ints _after_ 'main_running' has been cleared, else
       an interrupt could believe we'll pick up the work it left for
       us, but we won't see it anymore here... */
    main_running = 0;
    local_irq_restore(flags);
}


#ifdef REAL_DMA
/*
 * 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.
 *
 */

static void NCR5380_dma_complete( struct Scsi_Host *instance )
{
    SETUP_HOSTDATA(instance);
    int           transfered, saved_data = 0, overrun = 0, cnt, toPIO;
    unsigned char **data, p;
    volatile int  *count;

    if (!hostdata->connected) {
	printk(KERN_WARNING "scsi%d: received end of DMA interrupt with "
	       "no connected cmd\n", HOSTNO);
	return;
    }
    
    if (atari_read_overruns) {
	p = hostdata->connected->SCp.phase;
	if (p & SR_IO) {
	    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_REG);
		overrun = 1;
		DMA_PRINTK("scsi%d: read overrun handled\n", HOSTNO);
	    }
	}
    }

    DMA_PRINTK("scsi%d: real DMA transfer complete, basr 0x%X, sr 0x%X\n",
	       HOSTNO, NCR5380_read(BUS_AND_STATUS_REG),
	       NCR5380_read(STATUS_REG));

    (void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
    NCR5380_write(MODE_REG, MR_BASE);
    NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);

    transfered = hostdata->dma_len - NCR5380_dma_residual(instance);
    hostdata->dma_len = 0;

    data = (unsigned char **) &(hostdata->connected->SCp.ptr);
    count = &(hostdata->connected->SCp.this_residual);
    *data += transfered;
    *count -= transfered;

    if (atari_read_overruns) {
	if ((NCR5380_read(STATUS_REG) & PHASE_MASK) == p && (p & SR_IO)) {
	    cnt = toPIO = atari_read_overruns;
	    if (overrun) {
		DMA_PRINTK("Got an input overrun, using saved byte\n");
		*(*data)++ = saved_data;
		(*count)--;
		cnt--;
		toPIO--;
	    }
	    DMA_PRINTK("Doing %d-byte PIO to 0x%08lx\n", cnt, (long)*data);
	    NCR5380_transfer_pio(instance, &p, &cnt, data);
	    *count -= toPIO - cnt;
	}
    }
}
#endif /* REAL_DMA */


/*
 * Function : void NCR5380_intr (int irq)
 * 
 * Purpose : handle interrupts, reestablishing I_T_L or I_T_L_Q nexuses
 *	from the disconnected queue, and restarting NCR5380_main() 
 *	as required.
 *
 * Inputs : int irq, irq that caused this interrupt.
 *
 */

static irqreturn_t NCR5380_intr (int irq, void *dev_id)
{
    struct Scsi_Host *instance = first_instance;
    int done = 1, handled = 0;
    unsigned char basr;

    INT_PRINTK("scsi%d: NCR5380 irq triggered\n", HOSTNO);

    /* Look for pending interrupts */
    basr = NCR5380_read(BUS_AND_STATUS_REG);
    INT_PRINTK("scsi%d: BASR=%02x\n", HOSTNO, basr);
    /* dispatch to appropriate routine if found and done=0 */
    if (basr & BASR_IRQ) {
	NCR_PRINT(NDEBUG_INTR);
	if ((NCR5380_read(STATUS_REG) & (SR_SEL|SR_IO)) == (SR_SEL|SR_IO)) {
	    done = 0;
	    ENABLE_IRQ();
	    INT_PRINTK("scsi%d: SEL interrupt\n", HOSTNO);
	    NCR5380_reselect(instance);
	    (void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
	}
	else if (basr & BASR_PARITY_ERROR) {
	    INT_PRINTK("scsi%d: PARITY interrupt\n", HOSTNO);
	    (void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
	}
	else if ((NCR5380_read(STATUS_REG) & SR_RST) == SR_RST) {
	    INT_PRINTK("scsi%d: RESET interrupt\n", HOSTNO);
	    (void)NCR5380_read(RESET_PARITY_INTERRUPT_REG);
	}
	else {
	    /*  
	     * The rest of the interrupt conditions can occur only during a
	     * DMA transfer
	     */

#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_MODE) &&
		((basr & BASR_END_DMA_TRANSFER) || 
		 !(basr & BASR_PHASE_MATCH))) {
		    
		INT_PRINTK("scsi%d: PHASE MISM or EOP interrupt\n", HOSTNO);
		NCR5380_dma_complete( instance );
		done = 0;
		ENABLE_IRQ();
	    } else
#endif /* REAL_DMA */
	    {
/* MS: Ignore unknown phase mismatch interrupts (caused by EOP interrupt) */
		if (basr & BASR_PHASE_MATCH)
		    printk(KERN_NOTICE "scsi%d: unknown interrupt, "
			   "BASR 0x%x, MR 0x%x, SR 0x%x\n",
			   HOSTNO, basr, NCR5380_read(MODE_REG),
			   NCR5380_read(STATUS_REG));
		(void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
	    }
	} /* if !(SELECTION || PARITY) */
	handled = 1;
    } /* BASR & IRQ */
    else {
	printk(KERN_NOTICE "scsi%d: interrupt without IRQ bit set in BASR, "
	       "BASR 0x%X, MR 0x%X, SR 0x%x\n", HOSTNO, basr,
	       NCR5380_read(MODE_REG), NCR5380_read(STATUS_REG));
	(void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
    }
    
    if (!done) {
	INT_PRINTK("scsi%d: in int routine, calling main\n", HOSTNO);
	/* Put a call to NCR5380_main() on the queue... */
	queue_main();
    }
    return IRQ_RETVAL(handled);
}

#ifdef NCR5380_STATS
static void collect_stats(struct NCR5380_hostdata* hostdata, Scsi_Cmnd* cmd)
{
# ifdef NCR5380_STAT_LIMIT
    if (cmd->request_bufflen > NCR5380_STAT_LIMIT)
# endif
	switch (cmd->cmnd[0])
	{
	    case WRITE:
	    case WRITE_6:
	    case WRITE_10:
		hostdata->time_write[cmd->device->id] += (jiffies - hostdata->timebase);
		/*hostdata->bytes_write[cmd->device->id] += cmd->request_bufflen;*/
		hostdata->pendingw--;
		break;
	    case READ:
	    case READ_6:
	    case READ_10:
		hostdata->time_read[cmd->device->id] += (jiffies - hostdata->timebase);
		/*hostdata->bytes_read[cmd->device->id] += cmd->request_bufflen;*/
		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.
 */

static int NCR5380_select (struct Scsi_Host *instance, Scsi_Cmnd *cmd, int tag)
{
    SETUP_HOSTDATA(instance);
    unsigned char tmp[3], phase;
    unsigned char *data;
    int len;
    unsigned long timeout;
    unsigned long flags;

    hostdata->restart_select = 0;
    NCR_PRINT(NDEBUG_ARBITRATION);
    ARB_PRINTK("scsi%d: starting arbitration, id = %d\n", HOSTNO,
	       instance->this_id);

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

    local_irq_save(flags);
    if (hostdata->connected) {
	local_irq_restore(flags);
	return -1;
    }
    NCR5380_write(TARGET_COMMAND_REG, 0);


    /* 
     * Start arbitration.
     */
    
    NCR5380_write(OUTPUT_DATA_REG, hostdata->id_mask);
    NCR5380_write(MODE_REG, MR_ARBITRATE);

    local_irq_restore(flags);

    /* Wait for arbitration logic to complete */
#if defined(NCR_TIMEOUT)
    {
      unsigned long timeout = jiffies + 2*NCR_TIMEOUT;

      while (!(NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_PROGRESS)
	   && time_before(jiffies, timeout) && !hostdata->connected)
	;
      if (time_after_eq(jiffies, timeout))
      {
	printk("scsi : arbitration timeout at %d\n", __LINE__);
	NCR5380_write(MODE_REG, MR_BASE);
	NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
	return -1;
      }
    }
#else /* NCR_TIMEOUT */
    while (!(NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_PROGRESS)
	 && !hostdata->connected);
#endif

    ARB_PRINTK("scsi%d: arbitration complete\n", HOSTNO);

    if (hostdata->connected) {
	NCR5380_write(MODE_REG, MR_BASE); 
	return -1;
    }
    /* 
     * 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) ||
	hostdata->connected) {
	NCR5380_write(MODE_REG, MR_BASE); 
	ARB_PRINTK("scsi%d: lost arbitration, deasserting MR_ARBITRATE\n",
		   HOSTNO);
	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 ((NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST) ||
	hostdata->connected) {
	NCR5380_write(MODE_REG, MR_BASE);
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
	ARB_PRINTK("scsi%d: lost arbitration, deasserting ICR_ASSERT_SEL\n",
		   HOSTNO);
	return -1;
    }

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

#ifdef CONFIG_ATARI_SCSI_TOSHIBA_DELAY
    /* ++roman: But some targets (see above :-) seem to need a bit more... */
    udelay(15);
#else
    udelay(2);
#endif
    
    if (hostdata->connected) {
	NCR5380_write(MODE_REG, MR_BASE);
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
	return -1;
    }

    ARB_PRINTK("scsi%d: won arbitration\n", HOSTNO);

    /* 
     * 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 << cmd->device->id)));

    /* 
     * 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.
     */

    if (hostdata->connected) {
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
	return -1;
    }

    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);

    SEL_PRINTK("scsi%d: selecting target %d\n", HOSTNO, cmd->device->id);

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

    timeout = jiffies + 25; 

    /* 
     * 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.
     */

#if 0
    /* ++roman: If a target conformed to the SCSI standard, it wouldn't assert
     * IO while SEL is true. But again, there are some disks out the in the
     * world that do that nevertheless. (Somebody claimed that this announces
     * reselection capability of the target.) So we better skip that test and
     * only wait for BSY... (Famous german words: Der Klügere gibt nach :-)
     */

    while (time_before(jiffies, timeout) && !(NCR5380_read(STATUS_REG) & 
	(SR_BSY | SR_IO)));

    if ((NCR5380_read(STATUS_REG) & (SR_SEL | SR_IO)) == 
	    (SR_SEL | SR_IO)) {
	    NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
	    NCR5380_reselect(instance);
	    printk (KERN_ERR "scsi%d: reselection after won arbitration?\n",
		    HOSTNO);
	    NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
	    return -1;
    }
#else
    while (time_before(jiffies, timeout) && !(NCR5380_read(STATUS_REG) & SR_BSY));
#endif

    /* 
     * 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 << cmd->device->id)) {
	    printk(KERN_ERR "scsi%d: weirdness\n", HOSTNO);
	    if (hostdata->restart_select)
		printk(KERN_NOTICE "\trestart select\n");
	    NCR_PRINT(NDEBUG_ANY);
	    NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
	    return -1;
	}
	cmd->result = DID_BAD_TARGET << 16;
#ifdef NCR5380_STATS
	collect_stats(hostdata, cmd);
#endif
#ifdef SUPPORT_TAGS
	cmd_free_tag( cmd );
#endif
	cmd->scsi_done(cmd);
	NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
	SEL_PRINTK("scsi%d: target did not respond within 250ms\n", HOSTNO);
	NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
	return 0;
    } 

    hostdata->targets_present |= (1 << cmd->device->id);

    /*
     * 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 */
    while (!(NCR5380_read(STATUS_REG) & SR_REQ));

    SEL_PRINTK("scsi%d: target %d selected, going into MESSAGE OUT phase.\n",
	       HOSTNO, cmd->device->id);
    tmp[0] = IDENTIFY(1, cmd->device->lun);

#ifdef SUPPORT_TAGS
    if (cmd->tag != TAG_NONE) {
	tmp[1] = hostdata->last_message = SIMPLE_QUEUE_TAG;
	tmp[2] = cmd->tag;
	len = 3;
    } else 
	len = 1;
#else
    len = 1;
    cmd->tag=0;
#endif /* SUPPORT_TAGS */

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

    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 are 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)
{
    register unsigned char p = *phase, tmp;
    register int c = *count;
    register unsigned char *d = *data;

    /* 
     * 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 
	 */
	while (!((tmp = NCR5380_read(STATUS_REG)) & SR_REQ));

	HSH_PRINTK("scsi%d: REQ detected\n", HOSTNO);

	/* Check for phase mismatch */	
	if ((tmp & PHASE_MASK) != p) {
	    PIO_PRINTK("scsi%d: phase mismatch\n", HOSTNO);
	    NCR_PRINT_PHASE(NDEBUG_PIO);
	    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);
		NCR_PRINT(NDEBUG_PIO);
		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);
		NCR_PRINT(NDEBUG_PIO);
		NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | 
		    ICR_ASSERT_DATA | ICR_ASSERT_ATN | ICR_ASSERT_ACK);
	    }
	} else {
	    NCR_PRINT(NDEBUG_PIO);
	    NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ACK);
	}

	while (NCR5380_read(STATUS_REG) & SR_REQ);

	HSH_PRINTK("scsi%d: req false, handshake complete\n", HOSTNO);

/*
 * 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);

    PIO_PRINTK("scsi%d: residual %d\n", HOSTNO, 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 is the case if
     * we're in MSGIN and all wanted bytes have been received. */
    if ((tmp & SR_REQ) || (p == PHASE_MSGIN && c == 0))
	*phase = tmp & PHASE_MASK;
    else 
	*phase = PHASE_UNKNOWN;

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

/*
 * 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.
 */

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

    /* 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.
     */
    
    while (!(tmp = NCR5380_read(STATUS_REG)) & SR_REQ);

    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);
	while (NCR5380_read(STATUS_REG) & SR_REQ);
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_ATN);
    }
   
    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)
/* 
 * 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.
 *
 */


static int NCR5380_transfer_dma( struct Scsi_Host *instance, 
				 unsigned char *phase, int *count,
				 unsigned char **data)
{
    SETUP_HOSTDATA(instance);
    register int c = *count;
    register unsigned char p = *phase;
    register unsigned char *d = *data;
    unsigned char tmp;
    unsigned long flags;

    if ((tmp = (NCR5380_read(STATUS_REG) & PHASE_MASK)) != p) {
        *phase = tmp;
        return -1;
    }

    if (atari_read_overruns && (p & SR_IO)) {
	c -= atari_read_overruns;
    }

    DMA_PRINTK("scsi%d: initializing DMA for %s, %d bytes %s %p\n",
	       HOSTNO, (p & SR_IO) ? "reading" : "writing",
	       c, (p & SR_IO) ? "to" : "from", d);

    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);
#endif /* def REAL_DMA  */

    if (IS_A_TT()) {
	/* On the Medusa, it is a must to initialize the DMA before
	 * starting the NCR. This is also the cleaner way for the TT.
	 */
	local_irq_save(flags);
	hostdata->dma_len = (p & SR_IO) ?
	    NCR5380_dma_read_setup(instance, d, c) : 
	    NCR5380_dma_write_setup(instance, d, c);
	local_irq_restore(flags);
    }
    
    if (p & SR_IO)
	NCR5380_write(START_DMA_INITIATOR_RECEIVE_REG, 0);
    else {
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_DATA);
	NCR5380_write(START_DMA_SEND_REG, 0);
    }

    if (!IS_A_TT()) {
	/* On the Falcon, the DMA setup must be done after the last */
	/* NCR access, else the DMA setup gets trashed!
	 */