MMC: Fix for capacity calculation on eMMC

The current mmc driver returns erroneous capacity information for
  eMMC.  The capacity of eMMC devices is available only in the ext-CSD
  register.  This patch add code to read the ext-CDSD register and
  correctly calculate eMMC capacity.

Signed-off-by: Sukumar Ghorai <s-ghorai@ti.com>
Acked-by: Steve Sakoman <steve@sakoman.com>

drivers/mmc/mmc.c

@@ -627,6 +627,7 @@ int mmc_startup(struct mmc *mmc)
 	uint mult, freq;
 	u64 cmult, csize;
 	struct mmc_cmd cmd;
+	char ext_csd[512];
 
 	/* Put the Card in Identify Mode */
 	cmd.cmdidx = MMC_CMD_ALL_SEND_CID;
@@ -742,6 +743,16 @@ int mmc_startup(struct mmc *mmc)
 	if (err)
 		return err;
 
+	if (!IS_SD(mmc) && (mmc->version >= MMC_VERSION_4)) {
+		/* check  ext_csd version and capacity */
+		err = mmc_send_ext_csd(mmc, ext_csd);
+		if (!err & (ext_csd[192] >= 2)) {
+			mmc->capacity = ext_csd[212] << 0 | ext_csd[213] << 8 |
+					ext_csd[214] << 16 | ext_csd[215] << 24;
+			mmc->capacity *= 512;
+		}
+	}
+
 	if (IS_SD(mmc))
 		err = sd_change_freq(mmc);
 	else