[U-Boot] [PATCH v2] ppc/85xx: PIO Support for FSL eSDHC Controller Driver

[Dipen Dudhat]

On some Freescale SoC Internal DMA of eSDHC controller has bug.

So PIO Mode has introduced to do data transfer using CPU.
In PIO mode data transfer performance will be degraded by a large extent.

Note: 
In PIO mode multiple block read/write requires delay to complete the transfer.

Signed-off-by: Dipen Dudhat <dipen.dudhat at freescale.com>
---
Changes from v1:
- Integrated comments for error handling
- Formatting errors removed
 drivers/mmc/fsl_esdhc.c |   87 +++++++++++++++++++++++++++++++++++++++++++++-
 include/fsl_esdhc.h     |    2 +
 2 files changed, 87 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c
index 27e4c48..7db8c0c 100644
--- a/drivers/mmc/fsl_esdhc.c
+++ b/drivers/mmc/fsl_esdhc.c
@@ -73,8 +73,10 @@ uint esdhc_xfertyp(struct mmc_cmd *cmd, struct mmc_data *data)
 	uint xfertyp = 0;
 
 	if (data) {
-		xfertyp |= XFERTYP_DPSEL | XFERTYP_DMAEN;
-
+		xfertyp |= XFERTYP_DPSEL;
+#ifndef CONFIG_SYS_FSL_ESDHC_USE_PIO
+		xfertyp |= XFERTYP_DMAEN;
+#endif
 		if (data->blocks > 1) {
 			xfertyp |= XFERTYP_MSBSEL;
 			xfertyp |= XFERTYP_BCEN;
@@ -98,12 +100,88 @@ uint esdhc_xfertyp(struct mmc_cmd *cmd, struct mmc_data *data)
 	return XFERTYP_CMD(cmd->cmdidx) | xfertyp;
 }
 
+#ifdef CONFIG_SYS_FSL_ESDHC_USE_PIO
+/*
+ * PIO Read/Write Mode reduce the performace as DMA is not used in this mode.
+ */
+static int
+esdhc_pio_read_write(struct mmc *mmc, struct mmc_data *data)
+{
+	struct fsl_esdhc *regs = mmc->priv;
+	uint blocks;
+	char *buffer;
+	uint databuf;
+	uint size;
+	uint irqstat;
+	uint timeout;
+
+	if (data->flags & MMC_DATA_READ) {
+		blocks = data->blocks;
+		buffer = data->dest;
+		while (blocks) {
+			timeout = MAX_TIMEOUT;
+			size = data->blocksize;
+			irqstat = in_be32(&regs->irqstat);
+			while (!(in_be32(&regs->prsstat) & PRSSTAT_BREN)
+				&& --timeout);
+			if (timeout <= 0) {
+				printf("\nData Read Failed in PIO Mode.");
+				return TIMEOUT;
+			}
+			while (size && (!(irqstat & IRQSTAT_TC))) {
+				udelay(100);
+				irqstat = in_be32(&regs->irqstat);
+				databuf = in_le32(&regs->datport);
+				*((uint *)buffer) = databuf;
+				buffer += 4;
+				size -= 4;
+			}
+			blocks--;
+		}
+	} else {
+		blocks = data->blocks;
+		buffer = data->src;
+		while (blocks) {
+			timeout = MAX_TIMEOUT;
+			size = data->blocksize;
+			irqstat = in_be32(&regs->irqstat);
+			while (!(in_be32(&regs->prsstat) & PRSSTAT_BWEN)
+				&& --timeout);
+			if (timeout <= 0) {
+				printf("\nData Write Failed in PIO Mode.");
+				return TIMEOUT;
+			}
+			while (size && (!(irqstat & IRQSTAT_TC))) {
+				udelay(100);
+				databuf = *((uint *)buffer);
+				buffer += 4;
+				size -= 4;
+				irqstat = in_be32(&regs->irqstat);
+				out_le32(&regs->datport, databuf);
+			}
+			blocks--;
+		}
+	}
+}
+#endif
+
 static int esdhc_setup_data(struct mmc *mmc, struct mmc_data *data)
 {
 	uint wml_value;
 	int timeout;
 	struct fsl_esdhc *regs = mmc->priv;
 
+#ifdef CONFIG_SYS_FSL_ESDHC_USE_PIO
+	if (!(data->flags & MMC_DATA_READ)) {
+		if ((in_be32(&regs->prsstat) & PRSSTAT_WPSPL) == 0) {
+			printf("\nThe SD card is locked. "
+				"Can not write to a locked card.\n\n");
+			return TIMEOUT;
+		}
+		out_be32(&regs->dsaddr, (u32)data->src);
+	} else
+		out_be32(&regs->dsaddr, (u32)data->dest);
+#else
 	wml_value = data->blocksize/4;
 
 	if (data->flags & MMC_DATA_READ) {
@@ -125,6 +203,7 @@ static int esdhc_setup_data(struct mmc *mmc, struct mmc_data *data)
 	}
 
 	out_be32(&regs->wml, wml_value);
+#endif
 
 	out_be32(&regs->blkattr, data->blocks << 16 | data->blocksize);
 
@@ -217,6 +296,9 @@ esdhc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data)
 
 	/* Wait until all of the blocks are transferred */
 	if (data) {
+#ifdef CONFIG_SYS_FSL_ESDHC_USE_PIO
+		esdhc_pio_read_write(mmc, data);
+#else
 		do {
 			irqstat = in_be32(&regs->irqstat);
 
@@ -227,6 +309,7 @@ esdhc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data)
 				return TIMEOUT;
 		} while (!(irqstat & IRQSTAT_TC) &&
 				(in_be32(&regs->prsstat) & PRSSTAT_DLA));
+#endif
 	}
 
 	out_be32(&regs->irqstat, -1);
diff --git a/include/fsl_esdhc.h b/include/fsl_esdhc.h
index 89b8304..5948d37 100644
--- a/include/fsl_esdhc.h
+++ b/include/fsl_esdhc.h
@@ -86,6 +86,7 @@
 #define PRSSTAT_CDPL		(0x00040000)
 #define PRSSTAT_CINS		(0x00010000)
 #define PRSSTAT_BREN		(0x00000800)
+#define PRSSTAT_BWEN		(0x00000400)
 #define PRSSTAT_DLA		(0x00000004)
 #define PRSSTAT_CICHB		(0x00000002)
 #define PRSSTAT_CIDHB		(0x00000001)
@@ -117,6 +118,7 @@
 #define XFERTYP_DMAEN		0x00000001
 
 #define CINS_TIMEOUT		1000
+#define MAX_TIMEOUT		100000
 
 #define DSADDR		0x2e004
 
-- 
1.5.6.3