mmc: export eMMC4.4 enhanced area details to sysfs

Enhanced area feature is a new feature defined in eMMC4.4 standard. This
user data area provides higher performance/reliability, at the expense
of using twice the effective media space due to the area using SLC.

The MMC driver now reads out the enhanced area offset and size and adds
them to the device attributes in sysfs. Enabling the enhanced area can
only be done once, and should be done in manufacturing. To use this
feature, bit ERASE_GRP_DEF should also be set.

Documentation/ABI/testing/sysfs-devices-mmc describes the two new
attributes.

Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Reviewed-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
index 612301f..264ba54 100644
--- a/include/linux/mmc/mmc.h
+++ b/include/linux/mmc/mmc.h
@@ -253,6 +253,8 @@
  * EXT_CSD fields
  */
 
+#define EXT_CSD_PARTITION_ATTRIBUTE	156	/* R/W */
+#define EXT_CSD_PARTITION_SUPPORT	160	/* RO */
 #define EXT_CSD_ERASE_GROUP_DEF		175	/* R/W */
 #define EXT_CSD_ERASED_MEM_CONT		181	/* RO */
 #define EXT_CSD_BUS_WIDTH		183	/* R/W */
@@ -262,6 +264,7 @@
 #define EXT_CSD_CARD_TYPE		196	/* RO */
 #define EXT_CSD_SEC_CNT			212	/* RO, 4 bytes */
 #define EXT_CSD_S_A_TIMEOUT		217	/* RO */
+#define EXT_CSD_HC_WP_GRP_SIZE		221	/* RO */
 #define EXT_CSD_ERASE_TIMEOUT_MULT	223	/* RO */
 #define EXT_CSD_HC_ERASE_GRP_SIZE	224	/* RO */
 #define EXT_CSD_SEC_TRIM_MULT		229	/* RO */