[U-Boot] [PATCH] i.MX28: Enable SD DMA only if DCache enabled

[Marek Vasut]

This SD DMA function of i.MX28 is still apparently too experimental to be
enabled by default in 2012.04 release. Enable this feature only if the user
plans to tinker with DCache or explicitly enables it.

Signed-off-by: Marek Vasut <marex at denx.de>
Cc: Stefano Babic <sbabic at denx.de>
Cc: Wolfgang Denk <wd at denx.de>
Cc: Detlev Zundel <dzu at denx.de>
Cc: Fabio Estevam <fabio.estevam at freescale.com>
---
 drivers/mmc/mxsmmc.c |   46 +++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 45 insertions(+), 1 deletions(-)

diff --git a/drivers/mmc/mxsmmc.c b/drivers/mmc/mxsmmc.c
index e8bad9d..10b9d34 100644
--- a/drivers/mmc/mxsmmc.c
+++ b/drivers/mmc/mxsmmc.c
@@ -55,6 +55,11 @@ struct mxsmmc_priv {
 
 #define	MXSMMC_MAX_TIMEOUT	10000
 
+/* Enable DMA transfers only if DCache is on. */
+#ifndef CONFIG_SYS_DCACHE_OFF
+#define CONFIG_MXS_MMC_DMA
+#endif
+
 /*
  * Sends a command out on the bus.  Takes the mmc pointer,
  * a command pointer, and an optional data pointer.
@@ -66,8 +71,13 @@ mxsmmc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data)
 	struct mx28_ssp_regs *ssp_regs = priv->regs;
 	uint32_t reg;
 	int timeout;
-	uint32_t data_count, cache_data_count;
+	uint32_t data_count;
 	uint32_t ctrl0;
+#ifndef CONFIG_MXS_MMC_DMA
+	uint32_t *data_ptr;
+#else
+	uint32_t cache_data_count;
+#endif
 
 	debug("MMC%d: CMD%d\n", mmc->block_dev.dev, cmd->cmdidx);
 
@@ -185,7 +195,9 @@ mxsmmc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data)
 		return 0;
 
 	data_count = data->blocksize * data->blocks;
+	timeout = MXSMMC_MAX_TIMEOUT;
 
+#ifdef CONFIG_MXS_MMC_DMA
 	if (data_count % ARCH_DMA_MINALIGN)
 		cache_data_count = roundup(data_count, ARCH_DMA_MINALIGN);
 	else
@@ -218,6 +230,38 @@ mxsmmc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data)
 		invalidate_dcache_range((uint32_t)priv->desc->cmd.address,
 			(uint32_t)(priv->desc->cmd.address + cache_data_count));
 	}
+#else
+	if (data->flags & MMC_DATA_READ) {
+		data_ptr = (uint32_t *)data->dest;
+		while (data_count && --timeout) {
+			reg = readl(&ssp_regs->hw_ssp_status);
+			if (!(reg & SSP_STATUS_FIFO_EMPTY)) {
+				*data_ptr++ = readl(&ssp_regs->hw_ssp_data);
+				data_count -= 4;
+				timeout = MXSMMC_MAX_TIMEOUT;
+			} else
+				udelay(1000);
+		}
+	} else {
+		data_ptr = (uint32_t *)data->src;
+		timeout *= 100;
+		while (data_count && --timeout) {
+			reg = readl(&ssp_regs->hw_ssp_status);
+			if (!(reg & SSP_STATUS_FIFO_FULL)) {
+				writel(*data_ptr++, &ssp_regs->hw_ssp_data);
+				data_count -= 4;
+				timeout = MXSMMC_MAX_TIMEOUT;
+			} else
+				udelay(1000);
+		}
+	}
+
+	if (!timeout) {
+		printf("MMC%d: Data timeout with command %d (status 0x%08x)!\n",
+			mmc->block_dev.dev, cmd->cmdidx, reg);
+		return COMM_ERR;
+	}
+#endif
 
 	/* Check data errors */
 	reg = readl(&ssp_regs->hw_ssp_status);
-- 
1.7.9.1