[MMC] mmci: add data cache coherency

Since MMCI currently uses PIO to read data, we have to take steps
to ensure data cache coherency on aliasing CPU caches.  Add the
necessary flush_dcache_page() calls.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/mmc/mmci.c

@@ -20,6 +20,7 @@
 #include <linux/mmc/host.h>
 #include <linux/mmc/protocol.h>
 
+#include <asm/cacheflush.h>
 #include <asm/div64.h>
 #include <asm/io.h>
 #include <asm/scatterlist.h>
@@ -157,6 +158,13 @@ mmci_data_irq(struct mmci_host *host, struct mmc_data *data,
 		else if (status & (MCI_TXUNDERRUN|MCI_RXOVERRUN))
 			data->error = MMC_ERR_FIFO;
 		status |= MCI_DATAEND;
+
+		/*
+		 * We hit an error condition.  Ensure that any data
+		 * partially written to a page is properly coherent.
+		 */
+		if (host->sg_len && data->flags & MMC_DATA_READ)
+			flush_dcache_page(host->sg_ptr->page);
 	}
 	if (status & MCI_DATAEND) {
 		mmci_stop_data(host);
@@ -301,6 +309,13 @@ static irqreturn_t mmci_pio_irq(int irq, void *dev_id, struct pt_regs *regs)
 		if (remain)
 			break;
 
+		/*
+		 * If we were reading, and we have completed this
+		 * page, ensure that the data cache is coherent.
+		 */
+		if (status & MCI_RXACTIVE)
+			flush_dcache_page(host->sg_ptr->page);
+
 		if (!mmci_next_sg(host))
 			break;