mac_ncr5380.c

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	}
    }
}
#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 void NCR5380_intr (int irq, void *dev_id, struct pt_regs *regs)
{
    struct Scsi_Host *instance = first_instance;
    int done = 1;
    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) */
    } /* 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();
    }
}

#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->target] += (jiffies - hostdata->timebase);
		/*hostdata->bytes_write[cmd->target] += cmd->request_bufflen;*/
		hostdata->pendingw--;
		break;
	    case READ:
	    case READ_6:
	    case READ_10:
		hostdata->time_read[cmd->target] += (jiffies - hostdata->timebase);
		/*hostdata->bytes_read[cmd->target] += 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.
     */

    save_flags(flags);
    cli();
    if (hostdata->connected) {
	restore_flags(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);

    restore_flags(flags);

    /* Wait for arbitration logic to complete */
#if 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 [e-mail] 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->target)));

    /* 
     * 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->target);

    /* 
     * 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 Kl黦ere 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->target)) {
	    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->target);

    /*
     * 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",