[PATCH RFC 01/10] mmc: core: Add support to read command queue parameters

Ritesh Harjani
2016-06-15T13:02:12Z

From: Asutosh Das <asutoshd@codeaurora.org>

eMMC cards with EXT_CSD version >= 7, optionally support command
queuing feature as defined by JEDEC eMMC5.1. Add support for probing
command queue feature for such type of cards.

Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
[subhashj@codeaurora.org: fixed trivial merge conflicts]
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
---
drivers/mmc/core/mmc.c | 18 ++++++++++++++++++
include/linux/mmc/card.h | 2 ++
include/linux/mmc/mmc.h | 3 +++
3 files changed, 23 insertions(+)

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 4dbe3df..ff560e9 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -578,6 +578,24 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
card->ext_csd.data_sector_size = 512;
}

+ if (card->ext_csd.rev >= 7) {
+ card->ext_csd.cmdq_support = ext_csd[EXT_CSD_CMDQ_SUPPORT];
+ if (card->ext_csd.cmdq_support) {
+ /*
+ * Queue Depth = N + 1,
+ * see JEDEC JESD84-B51 section 7.4.19
+ */
+ card->ext_csd.cmdq_depth =
+ ext_csd[EXT_CSD_CMDQ_DEPTH] + 1;
+ pr_info("%s: CMDQ supported: depth: %d\n",
+ mmc_hostname(card->host),
+ card->ext_csd.cmdq_depth);
+ }
+ } else {
+ card->ext_csd.cmdq_support = 0;
+ card->ext_csd.cmdq_depth = 0;
+ }
+
/* eMMC v5 or later */
if (card->ext_csd.rev >= 7) {
memcpy(card->ext_csd.fwrev, &ext_csd[EXT_CSD_FIRMWARE_VERSION],
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index eb0151b..f74db84 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -118,6 +118,8 @@ struct mmc_ext_csd {
u8 raw_pwr_cl_ddr_200_360; /* 253 */
u8 raw_bkops_status; /* 246 */
u8 raw_sectors[4]; /* 212 - 4 bytes */
+ u8 cmdq_depth; /* 307 */
+ u8 cmdq_support; /* 308 */

unsigned int feature_support;
#define MMC_DISCARD_FEATURE BIT(0) /* CMD38 feature */
diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
index 15f2c4a..1c0ae75 100644
--- a/include/linux/mmc/mmc.h
+++ b/include/linux/mmc/mmc.h
@@ -330,6 +330,9 @@ struct _mmc_csd {
#define EXT_CSD_CACHE_SIZE 249 /* RO, 4 bytes */
#define EXT_CSD_PWR_CL_DDR_200_360 253 /* RO */
#define EXT_CSD_FIRMWARE_VERSION 254 /* RO, 8 bytes */
+#define EXT_CSD_CMDQ_DEPTH 307 /* RO */
+#define EXT_CSD_CMDQ_SUPPORT 308 /* RO */
+ #define EXT_CSD_TAG_UNIT_SIZE 498 /* RO */
#define EXT_CSD_SUPPORTED_MODE 493 /* RO */
#define EXT_CSD_TAG_UNIT_SIZE 498 /* RO */
#define EXT_CSD_DATA_TAG_SUPPORT 499 /* RO */