pxamci: support arbitrary block size

The PXA has two transmit FIFOes, each32 byte deep.  when one FIFO is
full and the other one has been transmitted, they are automatically
swapped and DMA is triggered for another 32 byte burst.  However, when
there is less than 32 bytes left to send, the FIFO swap has to be done
manually. This is required for some SDIO transfers which are not
required to be multiples of 32 bytes.

A DMA completion interrupt is set for each descriptor which length isn't
a multiple of 32 in order to force the FIFO swap.  While at it, the DMA
interrupt handler has been made a bit more resilient against errors.

Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

drivers/mmc/host/pxamci.c

@@ -142,14 +142,17 @@ static void pxamci_setup_data(struct pxamci_host *host, struct mmc_data *data)
 				   host->dma_dir);
 
 	for (i = 0; i < host->dma_len; i++) {
+		unsigned int length = sg_dma_len(&data->sg[i]);
+		host->sg_cpu[i].dcmd = dcmd | length;
+		if (length & 31 && !(data->flags & MMC_DATA_READ))
+			host->sg_cpu[i].dcmd |= DCMD_ENDIRQEN;
 		if (data->flags & MMC_DATA_READ) {
 			host->sg_cpu[i].dsadr = host->res->start + MMC_RXFIFO;
 			host->sg_cpu[i].dtadr = sg_dma_address(&data->sg[i]);
 		} else {
 			host->sg_cpu[i].dsadr = sg_dma_address(&data->sg[i]);
 			host->sg_cpu[i].dtadr = host->res->start + MMC_TXFIFO;
 		}
-		host->sg_cpu[i].dcmd = dcmd | sg_dma_len(&data->sg[i]);
 		host->sg_cpu[i].ddadr = host->sg_dma + (i + 1) *
 					sizeof(struct pxa_dma_desc);
 	}
@@ -414,8 +417,18 @@ static const struct mmc_host_ops pxamci_ops = {
 
 static void pxamci_dma_irq(int dma, void *devid)
 {
-	printk(KERN_ERR "DMA%d: IRQ???\n", dma);
-	DCSR(dma) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
+	struct pxamci_host *host = devid;
+	int dcsr = DCSR(dma);
+	DCSR(dma) = dcsr & ~DCSR_STOPIRQEN;
+
+	if (dcsr & DCSR_ENDINTR) {
+		writel(BUF_PART_FULL, host->base + MMC_PRTBUF);
+	} else {
+		printk(KERN_ERR "%s: DMA error on channel %d (DCSR=%#x)\n",
+		       mmc_hostname(host->mmc), dma, dcsr);
+		host->data->error = -EIO;
+		pxamci_data_done(host, 0);
+	}
 }
 
 static irqreturn_t pxamci_detect_irq(int irq, void *devid)