mmc: sdhci-esdhc-imx: add SDHCI_TRANSFER_MODE read function

Used to read out the correct value of SDHCI_TRANSFER_MODE register
for upper layer.
Signed-off-by: NDong Aisheng <b29396@freescale.com>
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci-esdhc-imx.c

@@ -385,6 +385,22 @@ static u16 esdhc_readw_le(struct sdhci_host *host, int reg)
 		return ret;
 	}
 
+	if (unlikely(reg == SDHCI_TRANSFER_MODE)) {
+		if (esdhc_is_usdhc(imx_data)) {
+			u32 m = readl(host->ioaddr + ESDHC_MIX_CTRL);
+			ret = m & ESDHC_MIX_CTRL_SDHCI_MASK;
+			/* Swap AC23 bit */
+			if (m & ESDHC_MIX_CTRL_AC23EN) {
+				ret &= ~ESDHC_MIX_CTRL_AC23EN;
+				ret |= SDHCI_TRNS_AUTO_CMD23;
+			}
+		} else {
+			ret = readw(host->ioaddr + SDHCI_TRANSFER_MODE);
+		}
+
+		return ret;
+	}
+
 	return readw(host->ioaddr + reg);
 }