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>

4 files changed, 101 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-mmc b/Documentation/ABI/testing/sysfs-devices-mmc
new file mode 100644
index 000000000000..5a50ab655843
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-mmc
@@ -0,0 +1,21 @@
+What:           /sys/devices/.../mmc_host/mmcX/mmcX:XXXX/enhanced_area_offset
+Date:           January 2011
+Contact:        Chuanxiao Dong <chuanxiao.dong@intel.com>
+Description:
+                Enhanced area is a new feature defined in eMMC4.4 standard.
+                eMMC4.4 or later card can support such feature. This kind of
+                area can help to improve the card performance. If the feature
+                is enabled, this attribute will indicate the start address of
+                enhanced data area. If not, this attribute will be -EINVAL.
+                Unit Byte. Format decimal.
+
+What:           /sys/devices/.../mmc_host/mmcX/mmcX:XXXX/enhanced_area_size
+Date:           January 2011
+Contact:        Chuanxiao Dong <chuanxiao.dong@intel.com>
+Description:
+                Enhanced area is a new feature defined in eMMC4.4 standard.
+                eMMC4.4 or later card can support such feature. This kind of
+                area can help to improve the card performance. If the feature
+                is enabled, this attribute will indicate the size of enhanced
+                data area. If not, this attribute will be -EINVAL.
+                Unit KByte. Format decimal.
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 16006ef153fe..6396c5d98e85 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -302,6 +302,44 @@ static int mmc_read_ext_csd(struct mmc_card *card)
         }
 
         if (card->ext_csd.rev >= 4) {
+                /*
+                 * Enhanced area feature support -- check whether the eMMC
+                 * card has the Enhanced area enabled.  If so, export enhanced
+                 * area offset and size to user by adding sysfs interface.
+                 */
+                if ((ext_csd[EXT_CSD_PARTITION_SUPPORT] & 0x2) &&
+                                (ext_csd[EXT_CSD_PARTITION_ATTRIBUTE] & 0x1)) {
+                        u8 hc_erase_grp_sz =
+                                ext_csd[EXT_CSD_HC_ERASE_GRP_SIZE];
+                        u8 hc_wp_grp_sz =
+                                ext_csd[EXT_CSD_HC_WP_GRP_SIZE];
+
+                        card->ext_csd.enhanced_area_en = 1;
+                        /*
+                         * calculate the enhanced data area offset, in bytes
+                         */
+                        card->ext_csd.enhanced_area_offset =
+                                (ext_csd[139] << 24) + (ext_csd[138] << 16) +
+                                (ext_csd[137] << 8) + ext_csd[136];
+                        if (mmc_card_blockaddr(card))
+                                card->ext_csd.enhanced_area_offset <<= 9;
+                        /*
+                         * calculate the enhanced data area size, in kilobytes
+                         */
+                        card->ext_csd.enhanced_area_size =
+                                (ext_csd[142] << 16) + (ext_csd[141] << 8) +
+                                ext_csd[140];
+                        card->ext_csd.enhanced_area_size *=
+                                (size_t)(hc_erase_grp_sz * hc_wp_grp_sz);
+                        card->ext_csd.enhanced_area_size <<= 9;
+                } else {
+                        /*
+                         * If the enhanced area is not enabled, disable these
+                         * device attributes.
+                         */
+                        card->ext_csd.enhanced_area_offset = -EINVAL;
+                        card->ext_csd.enhanced_area_size = -EINVAL;
+                }
                 card->ext_csd.sec_trim_mult =
                         ext_csd[EXT_CSD_SEC_TRIM_MULT];
                 card->ext_csd.sec_erase_mult =
@@ -336,6 +374,9 @@ MMC_DEV_ATTR(manfid, "0x%06x\n", card->cid.manfid);
 MMC_DEV_ATTR(name, "%s\n", card->cid.prod_name);
 MMC_DEV_ATTR(oemid, "0x%04x\n", card->cid.oemid);
 MMC_DEV_ATTR(serial, "0x%08x\n", card->cid.serial);
+MMC_DEV_ATTR(enhanced_area_offset, "%llu\n",
+                card->ext_csd.enhanced_area_offset);
+MMC_DEV_ATTR(enhanced_area_size, "%u\n", card->ext_csd.enhanced_area_size);
 
 static struct attribute *mmc_std_attrs[] = {
         &dev_attr_cid.attr,
@@ -349,6 +390,8 @@ static struct attribute *mmc_std_attrs[] = {
         &dev_attr_name.attr,
         &dev_attr_oemid.attr,
         &dev_attr_serial.attr,
+        &dev_attr_enhanced_area_offset.attr,
+        &dev_attr_enhanced_area_size.attr,
         NULL,
 };
 
@@ -484,6 +527,37 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
         }
 
         /*
+         * If enhanced_area_en is TRUE, host needs to enable ERASE_GRP_DEF
+         * bit.  This bit will be lost everytime after a reset or power off.
+         */
+        if (card->ext_csd.enhanced_area_en) {
+                err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+                                EXT_CSD_ERASE_GROUP_DEF, 1);
+
+                if (err && err != -EBADMSG)
+                        goto free_card;
+
+                if (err) {
+                        err = 0;
+                        /*
+                         * Just disable enhanced area off & sz
+                         * will try to enable ERASE_GROUP_DEF
+                         * during next time reinit
+                         */
+                        card->ext_csd.enhanced_area_offset = -EINVAL;
+                        card->ext_csd.enhanced_area_size = -EINVAL;
+                } else {
+                        card->ext_csd.erase_group_def = 1;
+                        /*
+                         * enable ERASE_GRP_DEF successfully.
+                         * This will affect the erase size, so
+                         * here need to reset erase size
+                         */
+                        mmc_set_erase_size(card);
+                }
+        }
+
+        /*
          * Activate high speed (if supported)
          */
         if ((card->ext_csd.hs_max_dtr != 0) &&
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 8ce082781ccb..4652cf9c5442 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -54,6 +54,9 @@ struct mmc_ext_csd {
         unsigned int            sec_trim_mult;  /* Secure trim multiplier  */
         unsigned int            sec_erase_mult; /* Secure erase multiplier */
         unsigned int            trim_timeout;           /* In milliseconds */
+        bool                    enhanced_area_en;       /* enable bit */
+        unsigned long long      enhanced_area_offset;   /* Units: Byte */
+        unsigned int            enhanced_area_size;     /* Units: KB */
 };
 
 struct sd_scr {
diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
index 612301f85d14..264ba5451e3b 100644
--- a/include/linux/mmc/mmc.h
+++ b/include/linux/mmc/mmc.h
@@ -253,6 +253,8 @@ struct _mmc_csd {
  * 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 @@ struct _mmc_csd {
 #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 */