mmc: mmci: add variant property to set command stop bit

On cmd12 (STOP_TRANSMISSION), STM32 sdmmc variant needs to set
cmdstop bit in command register. The CPSM ("Command Path State Machine")
treats the command as a Stop Transmission command and signals
abort to the DPSM ("Data Path State Machine").

Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index 13fa640..e352f5a 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>
@@ -274,6 +275,7 @@
 	.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,
@@ -1100,6 +1102,10 @@
 		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)