ncr5380.c

GNU Mach 微内核源代码, 基于美国卡内基美隆大学的 Mach 研究项目

			 *
			 * With successful commands, we fall through
			 * and see if we can do an information transfer,
			 * with failures we will restart.
			 */

			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 {
			    cli();
			    LIST(tmp, hostdata->issue_queue);
			    tmp->host_scribble = (unsigned char *) 
				hostdata->issue_queue;
			    hostdata->issue_queue = tmp;
			    done = 0;
			    sti();
#if (NDEBUG & (NDEBUG_MAIN | NDEBUG_QUEUES))
			printk("scsi%d : main(): select() failed, returned to issue_queue\n",
			    instance->host_no);
#endif
			}
		    } /* if target/lun is not busy */
		} /* for */
	    } /* if (!hostdata->connected) */
		
	    if (hostdata->connected 
#ifdef REAL_DMA
		&& !hostdata->dmalen
#endif
#ifdef USLEEP
		&& (!hostdata->time_expires || hostdata->time_expires >= jiffies)
#endif
		) {
		sti();
#if (NDEBUG & NDEBUG_MAIN)
		printk("scsi%d : main() : performing information transfer\n",
			instance->host_no);
#endif
		NCR5380_information_transfer(instance);
#if (NDEBUG & NDEBUG_MAIN)
		printk("scsi%d : main() : done set false\n", instance->host_no);
#endif
		done = 0;
	    } else 
		break;
	} /* for instance */
    } while (!done);
    main_running = 0;
}

#ifndef DONT_USE_INTR
/*
 * 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) {
    NCR5380_local_declare(); 
    struct Scsi_Host *instance;
    int done;
    unsigned char basr;
#if (NDEBUG & NDEBUG_INTR)
    printk("scsi : NCR5380 irq %d triggered\n", irq);
#endif
    do {
	done = 1;
	for (instance = first_instance; instance && (instance->hostt == 
	    the_template); instance = instance->next)
	    if (instance->irq == irq) {
		
		/* 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) {
#if (NDEBUG & NDEBUG_INTR)
		    NCR5380_print(instance);
#endif
		    if ((NCR5380_read(STATUS_REG) & (SR_SEL | SR_IO)) == 
			(SR_SEL | SR_IO)) {
			done = 0;
			sti();
#if (NDEBUG & NDEBUG_INTR)
			printk("scsi%d : SEL interrupt\n", instance->host_no);
#endif
			NCR5380_reselect(instance);
			(void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
		    } else if (basr & BASR_PARITY_ERROR) {
#if (NDEBUG & NDEBUG_INTR)
			printk("scsi%d : PARITY interrupt\n", instance->host_no);
#endif
			(void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
 		    } else if ((NCR5380_read(STATUS_REG) & SR_RST) == SR_RST) {
#if (NDEBUG & NDEBUG_INTR)
 			printk("scsi%d : RESET interrupt\n", instance->host_no);
#endif
			(void)NCR5380_read(RESET_PARITY_INTERRUPT_REG);
		    } else {
/*  
 * XXX the rest of the interrupt conditions should *only* occur during a 
 * DMA transfer, which I haven't gotten around to fixing yet.
 */

#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);
#if NCR_TIMEOUT
			    {
			      unsigned long timeout = jiffies + NCR_TIMEOUT;

			      while (NCR5380_read(BUS_AND_STATUS_REG) & BASR_ACK
				     && jiffies < timeout)
				;
			      if (jiffies >= timeout)
			        printk("scsi%d: timeout at NCR5380.c:%d\n", 
				    host->host_no, __LINE__);
			    }
#else /* NCR_TIMEOUT */
			    while (NCR5380_read(BUS_AND_STATUS_REG) & BASR_ACK);
#endif

			    NCR5380_write(MODE_REG, MR_BASE);
			    NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
			}
#else
#if (NDEBUG & NDEBUG_INTR)
		    printk("scsi : unknown interrupt, BASR 0x%X, MR 0x%X, SR 0x%x\n", basr, NCR5380_read(MODE_REG), NCR5380_read(STATUS_REG));
#endif
		    (void) NCR5380_read(RESET_PARITY_INTERRUPT_REG);
#endif
		    } 
		} /* if BASR_IRQ */
		if (!done) 
		    run_main();
	    } /* if (instance->irq == irq) */
    } while (!done);
}
#endif

#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) {
    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;
    NCR5380_setup(instance);

    hostdata->restart_select = 0;
#if defined (NDEBUG) && (NDEBUG & NDEBUG_ARBITRATION) 
    NCR5380_print(instance);
    printk("scsi%d : starting arbitration, id = %d\n", instance->host_no,
	instance->this_id);
#endif
    cli(); 

    /* 
     * 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);

    sti();

    /* 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)
	   && jiffies < timeout)
	;
      if (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));
#endif

#if (NDEBUG & NDEBUG_ARBITRATION) 
    printk("scsi%d : arbitration complete\n", instance->host_no);
/* Avoid GCC 2.4.5 asm needs to many reloads error */
    __asm__("nop");
#endif

    /* 
     * 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); 
#if (NDEBUG & NDEBUG_ARBITRATION)
    printk("scsi%d : lost arbitration, deasserting MR_ARBITRATE\n", 
	instance->host_no);
#endif
	return -1;
    }



    NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE | ICR_ASSERT_SEL);
    
    if (NCR5380_read(INITIATOR_COMMAND_REG) & ICR_ARBITRATION_LOST) {
	NCR5380_write(MODE_REG, MR_BASE);
	NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
#if (NDEBUG & NDEBUG_ARBITRATION)
    printk("scsi%d : lost arbitration, deasserting ICR_ASSERT_SEL\n", 
	instance->host_no);
#endif
	return -1;
    }

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

    udelay(2);	

#if (NDEBUG & NDEBUG_ARBITRATION)
    printk("scsi%d : won arbitration\n", instance->host_no);
#endif


    /* 
     * 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.
     */
    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);

#if (NDEBUG & NDEBUG_SELECTION)
    printk("scsi%d : selecting target %d\n", instance->host_no, cmd->target);
#endif

    /* 
     * 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.
     */

    while ((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 ("scsi%d : reselection after won arbitration?\n",
		instance->host_no);
	    NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
	    return -1;
    }

    /*