mmc: mmci: Add support to data commands via variant structure.

On some SOCs like Qcom there are explicit bits in the command register
to specify if its a data transfer command or not. So this patch adds
support to such bits in variant data, giving more flexibility to the
driver.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/mmci.c

@@ -59,6 +59,7 @@ static unsigned int fmax = 515633;
  *	      is asserted (likewise for RX)
  * @fifohalfsize: number of bytes that can be written when MCI_TXFIFOHALFEMPTY
  *		  is asserted (likewise for RX)
+ * @data_cmd_enable: enable value for data commands.
  * @sdio: variant supports SDIO
  * @st_clkdiv: true if using a ST-specific clock divider algorithm
  * @datactrl_mask_ddrmode: ddr mode mask in datactrl register.
@@ -79,6 +80,7 @@ struct variant_data {
 	unsigned int		datalength_bits;
 	unsigned int		fifosize;
 	unsigned int		fifohalfsize;
+	unsigned int		data_cmd_enable;
 	unsigned int		datactrl_mask_ddrmode;
 	bool			sdio;
 	bool			st_clkdiv;
@@ -841,6 +843,9 @@ mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c)
 	if (/*interrupt*/0)
 		c |= MCI_CPSM_INTERRUPT;
 
+	if (mmc_cmd_type(cmd) == MMC_CMD_ADTC)
+		c |= host->variant->data_cmd_enable;
+
 	host->cmd = cmd;
 
 	writel(cmd->arg, base + MMCIARGUMENT);