mmc: detect boot sectors using EXT_CSD_BOOT_MULT too

Some eMMC devices contain boot partitions, but do not set the PART_SUPPORT
bit in EXT_CSD_PARTITIONING_SUPPORT. Allow partition selection on such
devices, by enabling partition switching when EXT_CSD_BOOT_MULT is set.

Note that the Linux kernel enables access to boot partitions solely based
on the value of EXT_CSD_BOOT_MULT; EXT_CSD_PARTITIONING_SUPPORT only
influences access to "general" partitions.

eMMC devices affected by this issue exist on various NVIDIA Tegra
platforms (and presumably many others too), such as Harmony (plug-in eMMC),
Seaboard, Springbank, and Whistler (plug-in eMMC).

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>

drivers/mmc/mmc.c

@@ -1137,7 +1137,8 @@ int mmc_startup(struct mmc *mmc)
 		}
 
 		/* store the partition info of emmc */
-		if (ext_csd[EXT_CSD_PARTITIONING_SUPPORT] & PART_SUPPORT)
+		if ((ext_csd[EXT_CSD_PARTITIONING_SUPPORT] & PART_SUPPORT) ||
+		    ext_csd[EXT_CSD_BOOT_MULT])
 			mmc->part_config = ext_csd[EXT_CSD_PART_CONF];
 	}
 

include/mmc.h

@@ -160,6 +160,7 @@
 #define EXT_CSD_CARD_TYPE		196	/* RO */
 #define EXT_CSD_SEC_CNT			212	/* RO, 4 bytes */
 #define EXT_CSD_HC_ERASE_GRP_SIZE	224	/* RO */
+#define EXT_CSD_BOOT_MULT		226	/* RO */
 
 /*
  * EXT_CSD field definitions