mmc: core: new discard feature support at eMMC v4.5

MMC v4.5 supports the DISCARD feature (CMD38).  It's different from
trim and there's no check bit.  Currently it's only supported at v4.5.

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

2 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 711c3f8bfabd..551378508784 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -80,6 +80,9 @@ struct mmc_ext_csd {
         u8                      raw_sec_feature_support;/* 231 */
         u8                      raw_trim_mult;          /* 232 */
         u8                      raw_sectors[4];         /* 212 - 4 bytes */
+
+        unsigned int            feature_support;
+#define MMC_DISCARD_FEATURE     BIT(0)                  /* CMD38 feature */
 };
 
 struct sd_scr {
diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index 9585835cbc42..e918120235bd 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -146,6 +146,7 @@ extern int mmc_switch(struct mmc_card *, u8, u8, u8, unsigned int);
 #define MMC_ERASE_ARG           0x00000000
 #define MMC_SECURE_ERASE_ARG    0x80000000
 #define MMC_TRIM_ARG            0x00000001
+#define MMC_DISCARD_ARG         0x00000003
 #define MMC_SECURE_TRIM1_ARG    0x80000001
 #define MMC_SECURE_TRIM2_ARG    0x80008000
 
@@ -156,6 +157,7 @@ extern int mmc_erase(struct mmc_card *card, unsigned int from, unsigned int nr,
                      unsigned int arg);
 extern int mmc_can_erase(struct mmc_card *card);
 extern int mmc_can_trim(struct mmc_card *card);
+extern int mmc_can_discard(struct mmc_card *card);
 extern int mmc_can_sanitize(struct mmc_card *card);
 extern int mmc_can_secure_erase_trim(struct mmc_card *card);
 extern int mmc_erase_group_aligned(struct mmc_card *card, unsigned int from,