[PATCH v4 03/10] mmc: enable CMD23 for multi-block transfers

[Eric Chung]

Enable the support for the CMD23 (SET_BLOCK_COUNT) command to
manage multi-block read/write operations. This allows the MMC
core to use CMD23 in preference to the legacy CMD18/CMD25 plus
CMD12 sequence, reducing command overhead and improving I/O
performance on multi-block transfers.

Signed-off-by: Eric Chung <eric.chung at riscstar.com>
Signed-off-by: Tanmay Kathpalia <tanmay.kathpalia at altera.com>

---
v4:
- Add CMD23 on write.
- Fix on using CMD23 only for CMD18/CMD25.
v3:
- Avoid to use quirk to enable CMD23. Use capability instead.
---
 drivers/mmc/mmc.c       | 16 +++++++++++++++-
 drivers/mmc/mmc_write.c | 19 +++++++++++++++----
 include/mmc.h           |  3 +++
 3 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index f0e38efb262..9cd9307c8cd 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -461,6 +461,14 @@ static int mmc_read_blocks(struct mmc *mmc, void *dst, lbaint_t start,
 	struct mmc_cmd cmd;
 	struct mmc_data data;
 
+	if (blkcnt > 1 && mmc->host_caps & MMC_CAP_CMD23) {
+		cmd.cmdidx = MMC_CMD_SET_BLOCK_COUNT;
+		cmd.cmdarg = blkcnt & 0x0000ffff;
+		cmd.resp_type = MMC_RSP_R1;
+		if (mmc_send_cmd(mmc, &cmd, NULL))
+			return 0;
+	}
+
 	if (blkcnt > 1)
 		cmd.cmdidx = MMC_CMD_READ_MULTIPLE_BLOCK;
 	else
@@ -481,7 +489,7 @@ static int mmc_read_blocks(struct mmc *mmc, void *dst, lbaint_t start,
 	if (mmc_send_cmd(mmc, &cmd, &data))
 		return 0;
 
-	if (blkcnt > 1) {
+	if (blkcnt > 1 && !(mmc->host_caps & MMC_CAP_CMD23)) {
 		if (mmc_send_stop_transmission(mmc, false)) {
 #if !defined(CONFIG_XPL_BUILD) || defined(CONFIG_SPL_LIBCOMMON_SUPPORT)
 			log_err("mmc fail to send stop cmd\n");
@@ -1037,6 +1045,10 @@ static int mmc_get_capabilities(struct mmc *mmc)
 
 	mmc->card_caps = MMC_MODE_1BIT | MMC_CAP(MMC_LEGACY);
 
+	/* CMD23(SET_BLOCK_COUNT) requires eMMC spec v3.1 or above */
+	if (mmc->version < MMC_VERSION_3)
+		mmc->host_caps &= ~MMC_CAP_CMD23;
+
 	if (mmc_host_is_spi(mmc))
 		return 0;
 
@@ -1436,6 +1448,8 @@ static int sd_get_capabilities(struct mmc *mmc)
 
 	if (mmc->scr[0] & SD_DATA_4BIT)
 		mmc->card_caps |= MMC_MODE_4BIT;
+	if (!(mmc->scr[0] & SD_SCR_CMD23_SUPPORT))
+		mmc->host_caps &= ~MMC_CAP_CMD23;
 
 	/* Version 1.0 doesn't support switching */
 	if (mmc->version == SD_VERSION_1_0)
diff --git a/drivers/mmc/mmc_write.c b/drivers/mmc/mmc_write.c
index 928c05872ca..971e61295a1 100644
--- a/drivers/mmc/mmc_write.c
+++ b/drivers/mmc/mmc_write.c
@@ -165,7 +165,15 @@ static ulong mmc_write_blocks(struct mmc *mmc, lbaint_t start,
 
 	if (blkcnt == 0)
 		return 0;
-	else if (blkcnt == 1)
+	if (blkcnt > 1 && mmc->host_caps & MMC_CAP_CMD23) {
+		cmd.cmdidx = MMC_CMD_SET_BLOCK_COUNT;
+		cmd.cmdarg = blkcnt & 0x0000ffff;
+		cmd.resp_type = MMC_RSP_R1;
+		if (mmc_send_cmd(mmc, &cmd, NULL))
+			return 0;
+	}
+
+	if (blkcnt == 1)
 		cmd.cmdidx = MMC_CMD_WRITE_SINGLE_BLOCK;
 	else
 		cmd.cmdidx = MMC_CMD_WRITE_MULTIPLE_BLOCK;
@@ -191,10 +199,13 @@ static ulong mmc_write_blocks(struct mmc *mmc, lbaint_t start,
 		 */
 	}
 
-	/* SPI multiblock writes terminate using a special
-	 * token, not a STOP_TRANSMISSION request.
+	/*
+	 * SPI multiblock writes terminate using a special token, not CMD12.
+	 * When CMD23 was issued the card auto-terminates, so CMD12 is also
+	 * skipped in that case.
 	 */
-	if (!mmc_host_is_spi(mmc) && blkcnt > 1) {
+	if (!mmc_host_is_spi(mmc) && blkcnt > 1 &&
+	    !(mmc->host_caps & MMC_CAP_CMD23)) {
 		cmd.cmdidx = MMC_CMD_STOP_TRANSMISSION;
 		cmd.cmdarg = 0;
 		cmd.resp_type = MMC_RSP_R1b;
diff --git a/include/mmc.h b/include/mmc.h
index 9509c9e9543..4bda44ea220 100644
--- a/include/mmc.h
+++ b/include/mmc.h
@@ -67,6 +67,7 @@ struct bd_info;
 #define MMC_CAP_NONREMOVABLE	BIT(14)
 #define MMC_CAP_NEEDS_POLL	BIT(15)
 #define MMC_CAP_CD_ACTIVE_HIGH  BIT(16)
+#define MMC_CAP_CMD23		BIT(17)
 
 #define MMC_MODE_8BIT		BIT(30)
 #define MMC_MODE_4BIT		BIT(29)
@@ -141,6 +142,8 @@ static inline bool mmc_is_tuning_cmd(uint cmdidx)
 #define SD_HIGHSPEED_BUSY	0x00020000
 #define SD_HIGHSPEED_SUPPORTED	0x00020000
 
+#define SD_SCR_CMD23_SUPPORT	BIT(1)
+
 #define UHS_SDR12_BUS_SPEED	0
 #define HIGH_SPEED_BUS_SPEED	1
 #define UHS_SDR25_BUS_SPEED	1

-- 
2.51.0