[PATCH RFCv2 01/10] mmc: core: Add support to read command queue parameters

[Ritesh Harjani <riteshh@codeaurora.org>]

From: Asutosh Das <asutoshd@codeaurora.org>

eMMC cards with EXT_CSD version >= 8, 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>
Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>
---
 drivers/mmc/core/mmc.c   | 15 +++++++++++++++
 include/linux/mmc/card.h |  2 ++
 include/linux/mmc/mmc.h  |  2 ++
 3 files changed, 19 insertions(+)

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 5d438ad..77734c8 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -585,6 +585,21 @@ 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 >= 8) {
+		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_debug("%s: CMDQ supported: depth: %d\n",
+				mmc_hostname(card->host),
+				card->ext_csd.cmdq_depth);
+		}
+	}
+
 	/* 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..694c189 100644
--- a/include/linux/mmc/mmc.h
+++ b/include/linux/mmc/mmc.h
@@ -330,6 +330,8 @@ 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_SUPPORTED_MODE		493	/* RO */
 #define EXT_CSD_TAG_UNIT_SIZE		498	/* RO */
 #define EXT_CSD_DATA_TAG_SUPPORT	499	/* RO */
-- 
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