drivers/scsi/atari_scsi.c

Source file repositories/reference/linux-study-clean/drivers/scsi/atari_scsi.c

File Facts

System
Linux kernel
Corpus path
drivers/scsi/atari_scsi.c
Extension
.c
Size
27515 bytes
Lines
899
Domain
Driver Families
Bucket
drivers/scsi
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

if (!scsi_dma_is_ignored_buserr(dma_stat)) {
			printk(KERN_ERR "SCSI DMA caused bus error near 0x%08lx\n",
			       SCSI_DMA_READ_P(dma_addr));
			printk(KERN_CRIT "SCSI DMA bus error -- bad DMA programming!");
		}
	}

	/* If the DMA is active but not finished, we have the case
	 * that some other 5380 interrupt occurred within the DMA transfer.
	 * This means we have residual bytes, if the desired end address
	 * is not yet reached. Maybe we have to fetch some bytes from the
	 * rest data register, too. The residual must be calculated from
	 * the address pointer, not the counter register, because only the
	 * addr reg counts bytes not yet written and pending in the rest
	 * data reg!
	 */
	if ((dma_stat & 0x02) && !(dma_stat & 0x40)) {
		atari_dma_residual = hostdata->dma_len -
			(SCSI_DMA_READ_P(dma_addr) - atari_dma_startaddr);

		dprintk(NDEBUG_DMA, "SCSI DMA: There are %ld residual bytes.\n",
			   atari_dma_residual);

		if ((signed int)atari_dma_residual < 0)
			atari_dma_residual = 0;
		if ((dma_stat & 1) == 0) {
			/*
			 * After read operations, we maybe have to
			 * transport some rest bytes
			 */
			atari_scsi_fetch_restbytes();
		} else {
			/*
			 * There seems to be a nasty bug in some SCSI-DMA/NCR
			 * combinations: If a target disconnects while a write
			 * operation is going on, the address register of the
			 * DMA may be a few bytes farer than it actually read.
			 * This is probably due to DMA prefetching and a delay
			 * between DMA and NCR.  Experiments showed that the
			 * dma_addr is 9 bytes to high, but this could vary.
			 * The problem is, that the residual is thus calculated
			 * wrong and the next transfer will start behind where
			 * it should.  So we round up the residual to the next
			 * multiple of a sector size, if it isn't already a
			 * multiple and the originally expected transfer size
			 * was.  The latter condition is there to ensure that
			 * the correction is taken only for "real" data
			 * transfers and not for, e.g., the parameters of some
			 * other command.  These shouldn't disconnect anyway.
			 */
			if (atari_dma_residual & 0x1ff) {
				dprintk(NDEBUG_DMA, "SCSI DMA: DMA bug corrected, "
					   "difference %ld bytes\n",
					   512 - (atari_dma_residual & 0x1ff));
				atari_dma_residual = (atari_dma_residual + 511) & ~0x1ff;
			}
		}
		tt_scsi_dma.dma_ctrl = 0;
	}

	/* If the DMA is finished, fetch the rest bytes and turn it off */
	if (dma_stat & 0x40) {
		atari_dma_residual = 0;
		if ((dma_stat & 1) == 0)
			atari_scsi_fetch_restbytes();
		tt_scsi_dma.dma_ctrl = 0;
	}

	NCR5380_intr(irq, dev);

	return IRQ_HANDLED;
}


static irqreturn_t scsi_falcon_intr(int irq, void *dev)
{
	struct Scsi_Host *instance = dev;
	struct NCR5380_hostdata *hostdata = shost_priv(instance);
	int dma_stat;

	/* Turn off DMA and select sector counter register before
	 * accessing the status register (Atari recommendation!)
	 */
	st_dma.dma_mode_status = 0x90;
	dma_stat = st_dma.dma_mode_status;

	/* Bit 0 indicates some error in the DMA process... don't know
	 * what happened exactly (no further docu).
	 */
	if (!(dma_stat & 0x01)) {

Annotation

Implementation Notes