[PATCH V2 2/2] mmc: mmci: add variant property to send stop cmd if a command fail

[Ludovic Barre <ludovic.Barre@st.com>]

From: Ludovic Barre <ludovic.barre@st.com>

The mmc framework follows the requirement of SD_Specification:
the STOP_TRANSMISSION is sent on multiple write/read commands
and the stop command (alone), not needed on other ADTC commands.

But, if an error happens on command or data transmission, some
variants require a stop command "STOP_TRANSMISION" to clear the DPSM
"Data Path State Machine". If it's not done the next data
command freezes hardware block.
Needed to support the STM32 sdmmc variant.

Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
---
 drivers/mmc/host/mmci.c | 33 +++++++++++++++++++++++++++++++++
 drivers/mmc/host/mmci.h |  4 ++++
 2 files changed, 37 insertions(+)

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index 13fa640..47b865d 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -21,6 +21,7 @@
 #include <linux/err.h>
 #include <linux/highmem.h>
 #include <linux/log2.h>
+#include <linux/mmc/mmc.h>
 #include <linux/mmc/pm.h>
 #include <linux/mmc/host.h>
 #include <linux/mmc/card.h>
@@ -57,6 +58,8 @@ void sdmmc_variant_init(struct mmci_host *host);
 #else
 static inline void sdmmc_variant_init(struct mmci_host *host) {}
 #endif
+static void
+mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c);
 
 static unsigned int fmax = 515633;
 
@@ -274,6 +277,7 @@ static struct variant_data variant_stm32_sdmmc = {
 	.cmdreg_lrsp_crc	= MCI_CPSM_STM32_LRSP_CRC,
 	.cmdreg_srsp_crc	= MCI_CPSM_STM32_SRSP_CRC,
 	.cmdreg_srsp		= MCI_CPSM_STM32_SRSP,
+	.cmdreg_stop		= MCI_CPSM_STM32_CMDSTOP,
 	.data_cmd_enable	= MCI_CPSM_STM32_CMDTRANS,
 	.irq_pio_mask		= MCI_IRQ_PIO_STM32_MASK,
 	.datactrl_first		= true,
@@ -573,6 +577,24 @@ void mmci_dma_error(struct mmci_host *host)
 static void
 mmci_request_end(struct mmci_host *host, struct mmc_request *mrq)
 {
+	/*
+	 * If an error happens on command or data transmission, some variants
+	 * require a stop command to reinit the DPSM.
+	 * If it's not done the next data command freeze hardware block.
+	 */
+	if (host->variant->cmdreg_stop) {
+		u32 dpsm;
+
+		dpsm = readl_relaxed(host->base + MMCISTATUS);
+		dpsm &= MCI_STM32_DPSMACTIVE;
+
+		if (dpsm && ((mrq->cmd && mrq->cmd->error) ||
+			     (mrq->data && mrq->data->error))) {
+			mmci_start_command(host, &host->stop_abort, 0);
+			return;
+		}
+	}
+
 	writel(0, host->base + MMCICOMMAND);
 
 	BUG_ON(host->data);
@@ -1100,6 +1122,10 @@ mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c)
 		mmci_reg_delay(host);
 	}
 
+	if (host->variant->cmdreg_stop &&
+	    cmd->opcode == MMC_STOP_TRANSMISSION)
+		c |= host->variant->cmdreg_stop;
+
 	c |= cmd->opcode | host->variant->cmdreg_cpsm_enable;
 	if (cmd->flags & MMC_RSP_PRESENT) {
 		if (cmd->flags & MMC_RSP_136)
@@ -1950,6 +1976,13 @@ static int mmci_probe(struct amba_device *dev,
 		mmc->max_busy_timeout = 0;
 	}
 
+	/* prepare the stop command, used to abort and reinitialized the DPSM */
+	if (variant->cmdreg_stop) {
+		host->stop_abort.opcode = MMC_STOP_TRANSMISSION;
+		host->stop_abort.arg = 0;
+		host->stop_abort.flags = MMC_RSP_R1B | MMC_CMD_AC;
+	}
+
 	mmc->ops = &mmci_ops;
 
 	/* We support these PM capabilities. */
diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
index 550dd39..35372cd 100644
--- a/drivers/mmc/host/mmci.h
+++ b/drivers/mmc/host/mmci.h
@@ -161,6 +161,7 @@
 #define MCI_ST_CEATAEND		(1 << 23)
 #define MCI_ST_CARDBUSY		(1 << 24)
 /* Extended status bits for the STM32 variants */
+#define MCI_STM32_DPSMACTIVE	BIT(12)
 #define MCI_STM32_BUSYD0	BIT(20)
 
 #define MMCICLEAR		0x038
@@ -264,6 +265,7 @@ struct mmci_host;
  * @cmdreg_lrsp_crc: enable value for long response with crc
  * @cmdreg_srsp_crc: enable value for short response with crc
  * @cmdreg_srsp: enable value for short response without crc
+ * @cmdreg_stop: enable value for stop and abort transmission
  * @datalength_bits: number of bits in the MMCIDATALENGTH register
  * @fifosize: number of bytes that can be written when MMCI_TXFIFOEMPTY
  *	      is asserted (likewise for RX)
@@ -316,6 +318,7 @@ struct variant_data {
 	unsigned int		cmdreg_lrsp_crc;
 	unsigned int		cmdreg_srsp_crc;
 	unsigned int		cmdreg_srsp;
+	unsigned int		cmdreg_stop;
 	unsigned int		datalength_bits;
 	unsigned int		fifosize;
 	unsigned int		fifohalfsize;
@@ -375,6 +378,7 @@ struct mmci_host {
 	void __iomem		*base;
 	struct mmc_request	*mrq;
 	struct mmc_command	*cmd;
+	struct mmc_command	stop_abort;
 	struct mmc_data		*data;
 	struct mmc_host		*mmc;
 	struct clk		*clk;
-- 
2.7.4