[MMC] MMCI: use bio_kmap_irq() rather than req->buffer

This is in preparation for SG data IO.

drivers/mmc/mmci.c

@@ -196,7 +196,7 @@ static int mmci_pio_read(struct mmci_host *host, struct request *req, u32 status
 	int ret = 0;
 
 	do {
-		unsigned int count;
+		unsigned long flags;
 		char *buffer;
 
 		/*
@@ -205,8 +205,13 @@ static int mmci_pio_read(struct mmci_host *host, struct request *req, u32 status
 		if (!(status & MCI_RXDATAAVLBL))
 			break;
 
-		buffer = req->buffer;
-		count = host->size - (readl(base + MMCIFIFOCNT) << 2);
+		/*
+		 * Map the BIO buffer.
+		 */
+		buffer = bio_kmap_irq(req->bio, &flags);
+
+		do {
+			int count = host->size - (readl(base + MMCIFIFOCNT) << 2);
 
 			if (count > 0) {
 				ret = 1;
@@ -216,7 +221,11 @@ static int mmci_pio_read(struct mmci_host *host, struct request *req, u32 status
 			}
 
 			status = readl(base + MMCISTATUS);
-	} while (status & MCI_RXDATAAVLBL);
+		} while (status & MCI_RXDATAAVLBL && host->size);
+
+		bio_kunmap_irq(buffer, &flags);
+		break;
+	} while (1);
 
 	return ret;
 }
@@ -227,7 +236,7 @@ static int mmci_pio_write(struct mmci_host *host, struct request *req, u32 statu
 	int ret = 0;
 
 	do {
-		unsigned int count, maxcnt;
+		unsigned long flags;
 		char *buffer;
 
 		/*
@@ -238,20 +247,30 @@ static int mmci_pio_write(struct mmci_host *host, struct request *req, u32 statu
 		if (!(status & MCI_TXFIFOHALFEMPTY))
 			break;
 
-		buffer = req->buffer;
+		/*
+		 * Map the BIO buffer.
+		 */
+		buffer = bio_kmap_irq(req->bio, &flags);
+
+		do {
+			unsigned int count, maxcnt;
+
 			maxcnt = status & MCI_TXFIFOEMPTY ?
 				 MCI_FIFOSIZE : MCI_FIFOHALFSIZE;
 			count = min(host->size, maxcnt);
 
 			writesl(base + MMCIFIFO, buffer + host->offset, count >> 2);
-
 			host->offset += count;
 			host->size -= count;
 
 			ret = 1;
 
 			status = readl(base + MMCISTATUS);
-	} while (status & MCI_TXFIFOHALFEMPTY);
+		} while (status & MCI_TXFIFOHALFEMPTY && host->size);
+
+		bio_kunmap_irq(buffer, &flags);
+		break;
+	} while (1);
 
 	return ret;
 }