[PATCH] mmc: dw_mmc: change to use recommended reset procedure

[Yuvaraj Kumar C D]

From: Sonny Rao <sonnyrao at chromium.org>

This patch changes the fifo reset code to follow the reset procedure
outlined in the documentation of Synopsys  Mobile storage host databook
7.2.13.
Without this patch, we could able to see eMMC was not detected after
multiple reboots due to driver hangs while eMMC tuning for HS200.

Signed-off-by: Sonny Rao <sonnyrao at chromium.org>
Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd at samsung.org>
---
 drivers/mmc/host/dw_mmc.c |   48 ++++++++++++++++++++++++++++++++++++++++++++-
 drivers/mmc/host/dw_mmc.h |    1 +
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 32dd81d..1d77431 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -2220,7 +2220,53 @@ static inline bool dw_mci_fifo_reset(struct dw_mci *host)
 		host->sg = NULL;
 	}
 
-	return dw_mci_ctrl_reset(host, SDMMC_CTRL_FIFO_RESET);
+	/*
+	 * The recommended method for resetting is to always reset the
+	 * controller and the fifo, but differs slightly depending on the mode.
+	 * Note that this doesn't handle the "generic DMA" (not IDMAC) case.
+	 */
+	if (dw_mci_ctrl_reset(host, SDMMC_CTRL_RESET | SDMMC_CTRL_FIFO_RESET)) {
+		unsigned long timeout = jiffies + msecs_to_jiffies(500);
+		u32 status, rint;
+
+		/* if using dma we wait for dma_req to clear */
+		if (host->using_dma) {
+			do {
+				status = mci_readl(host, STATUS);
+				if (!(status & SDMMC_STATUS_DMA_REQ))
+					break;
+				cpu_relax();
+			} while (time_before(jiffies, timeout));
+
+			if (status & SDMMC_STATUS_DMA_REQ)
+				dev_err(host->dev,
+					"%s: Timeout waiting for dma_req to "
+					"clear during reset", __func__);
+
+			/* when using DMA next we reset the fifo again */
+			dw_mci_ctrl_reset(host, SDMMC_CTRL_FIFO_RESET);
+		}
+		/*
+		 * In all cases we clear the RAWINTS register to clear any
+		 * interrupts.
+		 */
+		rint = mci_readl(host, RINTSTS);
+		rint = rint & (~mci_readl(host, MINTSTS));
+		if (rint)
+			mci_writel(host, RINTSTS, rint);
+
+	} else
+		dev_err(host->dev, "%s: Reset bits didn't clear", __func__);
+
+ #ifdef CONFIG_MMC_DW_IDMAC
+	/* It is also recommended that we reset and reprogram idmac */
+	dw_mci_idmac_reset(host);
+ #endif
+
+	/* After a CTRL reset we need to have CIU set clock registers  */
+	mci_send_cmd(host->cur_slot, SDMMC_CMD_UPD_CLK, 0);
+
+	return true;
 }
 
 static inline bool dw_mci_ctrl_all_reset(struct dw_mci *host)
diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
index 738fa24..037e47a 100644
--- a/drivers/mmc/host/dw_mmc.h
+++ b/drivers/mmc/host/dw_mmc.h
@@ -129,6 +129,7 @@
 #define SDMMC_CMD_INDX(n)		((n) & 0x1F)
 /* Status register defines */
 #define SDMMC_GET_FCNT(x)		(((x)>>17) & 0x1FFF)
+#define SDMMC_STATUS_DMA_REQ		BIT(31)
 /* FIFOTH register defines */
 #define SDMMC_SET_FIFOTH(m, r, t)	(((m) & 0x7) << 28 | \
 					 ((r) & 0xFFF) << 16 | \
-- 
1.7.10.4