mmc: support hs400 enhanced strobe mode

eMMC 5.1+ supports HS400 Enhances Strobe mode without the need for
tuning procedure.
The flow is as following:
 - set HS_TIMIMG (Highspeed)
 - Host change freq to <= 52Mhz
 - set the bus width to Enhanced strobe and DDR8Bit(CMD6),
   EXT_CSD[183] = 0x86 instead of 0x80
 - set HS_TIMING to 0x3 (HS400)
 - Host change freq to <= 200Mhz
 - Host select HS400 enhanced strobe complete

Signed-off-by: Peng Fan <peng.fan@nxp.com>

4 files changed, 115 insertions, 1 deletions

diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
index a4a6a6c085..890ef358a0 100644
--- a/drivers/mmc/Kconfig
+++ b/drivers/mmc/Kconfig
@@ -135,6 +135,18 @@ config SPL_MMC_UHS_SUPPORT
 	  cards. The IO voltage must be switchable from 3.3v to 1.8v. The bus
 	  frequency can go up to 208MHz (SDR104)
 
+config MMC_HS400_ES_SUPPORT
+	bool "enable HS400 Enhanced Strobe support"
+	help
+	  The HS400 Enhanced Strobe mode is support by some eMMC. The bus
+	  frequency is up to 200MHz. This mode does not tune the IO.
+
+config SPL_MMC_HS400_ES_SUPPORT
+	bool "enable HS400 Enhanced Strobe support in SPL"
+	help
+	  The HS400 Enhanced Strobe mode is support by some eMMC. The bus
+	  frequency is up to 200MHz. This mode does not tune the IO.
+
 config MMC_HS400_SUPPORT
 	bool "enable HS400 support"
 	select MMC_HS200_SUPPORT
diff --git a/drivers/mmc/mmc-uclass.c b/drivers/mmc/mmc-uclass.c
index 9327c8302d..8bf63bbd9c 100644
--- a/drivers/mmc/mmc-uclass.c
+++ b/drivers/mmc/mmc-uclass.c
@@ -105,6 +105,23 @@ int mmc_execute_tuning(struct mmc *mmc, uint opcode)
 }
 #endif
 
+#if CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)
+int dm_mmc_set_enhanced_strobe(struct udevice *dev)
+{
+	struct dm_mmc_ops *ops = mmc_get_ops(dev);
+
+	if (ops->set_enhanced_strobe)
+		return ops->set_enhanced_strobe(dev);
+
+	return -ENOTSUPP;
+}
+
+int mmc_set_enhanced_strobe(struct mmc *mmc)
+{
+	return dm_mmc_set_enhanced_strobe(mmc->dev);
+}
+#endif
+
 int mmc_of_parse(struct udevice *dev, struct mmc_config *cfg)
 {
 	int val;
diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 2a1ba6e51d..c9aa13b409 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -148,6 +148,7 @@ const char *mmc_mode_name(enum bus_mode mode)
 	      [MMC_DDR_52]	= "MMC DDR52 (52MHz)",
 	      [MMC_HS_200]	= "HS200 (200MHz)",
 	      [MMC_HS_400]	= "HS400 (200MHz)",
+	      [MMC_HS_400_ES]	= "HS400ES (200MHz)",
 	};
 
 	if (mode >= MMC_MODES_END)
@@ -173,6 +174,7 @@ static uint mmc_mode2freq(struct mmc *mmc, enum bus_mode mode)
 	      [UHS_SDR104]	= 208000000,
 	      [MMC_HS_200]	= 200000000,
 	      [MMC_HS_400]	= 200000000,
+	      [MMC_HS_400_ES]	= 200000000,
 	};
 
 	if (mode == MMC_LEGACY)
@@ -839,6 +841,11 @@ static int mmc_set_card_speed(struct mmc *mmc, enum bus_mode mode,
 		speed_bits = EXT_CSD_TIMING_HS400;
 		break;
 #endif
+#if CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)
+	case MMC_HS_400_ES:
+		speed_bits = EXT_CSD_TIMING_HS400;
+		break;
+#endif
 	case MMC_LEGACY:
 		speed_bits = EXT_CSD_TIMING_LEGACY;
 		break;
@@ -909,7 +916,8 @@ static int mmc_get_capabilities(struct mmc *mmc)
 		mmc->card_caps |= MMC_MODE_HS200;
 	}
 #endif
-#if CONFIG_IS_ENABLED(MMC_HS400_SUPPORT)
+#if CONFIG_IS_ENABLED(MMC_HS400_SUPPORT) || \
+	CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)
 	if (cardtype & (EXT_CSD_CARD_TYPE_HS400_1_2V |
 			EXT_CSD_CARD_TYPE_HS400_1_8V)) {
 		mmc->card_caps |= MMC_MODE_HS400;
@@ -923,6 +931,13 @@ static int mmc_get_capabilities(struct mmc *mmc)
 	if (cardtype & EXT_CSD_CARD_TYPE_26)
 		mmc->card_caps |= MMC_MODE_HS;
 
+#if CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)
+	if (ext_csd[EXT_CSD_STROBE_SUPPORT] &&
+	    (mmc->card_caps & MMC_MODE_HS400)) {
+		mmc->card_caps |= MMC_MODE_HS400_ES;
+	}
+#endif
+
 	return 0;
 }
 #endif
@@ -1799,6 +1814,7 @@ static int mmc_set_lowest_voltage(struct mmc *mmc, enum bus_mode mode,
 	u32 card_mask = 0;
 
 	switch (mode) {
+	case MMC_HS_400_ES:
 	case MMC_HS_400:
 	case MMC_HS_200:
 		if (mmc->cardtype & (EXT_CSD_CARD_TYPE_HS200_1_8V |
@@ -1841,6 +1857,12 @@ static inline int mmc_set_lowest_voltage(struct mmc *mmc, enum bus_mode mode,
 #endif
 
 static const struct mode_width_tuning mmc_modes_by_pref[] = {
+#if CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)
+	{
+		.mode = MMC_HS_400_ES,
+		.widths = MMC_MODE_8BIT,
+	},
+#endif
 #if CONFIG_IS_ENABLED(MMC_HS400_SUPPORT)
 	{
 		.mode = MMC_HS_400,
@@ -1938,6 +1960,47 @@ static int mmc_select_hs400(struct mmc *mmc)
 }
 #endif
 
+#if CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)
+#if !CONFIG_IS_ENABLED(DM_MMC)
+static int mmc_set_enhanced_strobe(struct mmc *mmc)
+{
+	return -ENOTSUPP;
+}
+#endif
+static int mmc_select_hs400es(struct mmc *mmc)
+{
+	int err;
+
+	err = mmc_set_card_speed(mmc, MMC_HS, true);
+	if (err)
+		return err;
+
+	err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_BUS_WIDTH,
+			 EXT_CSD_BUS_WIDTH_8 | EXT_CSD_DDR_FLAG |
+			 EXT_CSD_BUS_WIDTH_STROBE);
+	if (err) {
+		printf("switch to bus width for hs400 failed\n");
+		return err;
+	}
+	/* TODO: driver strength */
+	err = mmc_set_card_speed(mmc, MMC_HS_400_ES, false);
+	if (err)
+		return err;
+
+	mmc_select_mode(mmc, MMC_HS_400_ES);
+	err = mmc_set_clock(mmc, mmc->tran_speed, false);
+	if (err)
+		return err;
+
+	return mmc_set_enhanced_strobe(mmc);
+}
+#else
+static int mmc_select_hs400es(struct mmc *mmc)
+{
+	return -ENOTSUPP;
+}
+#endif
+
 #define for_each_supported_width(caps, ddr, ecbv) \
 	for (ecbv = ext_csd_bus_width;\
 	    ecbv < ext_csd_bus_width + ARRAY_SIZE(ext_csd_bus_width);\
@@ -2016,6 +2079,13 @@ static int mmc_select_mode_and_width(struct mmc *mmc, uint card_caps)
 					printf("Select HS400 failed %d\n", err);
 					goto error;
 				}
+			} else if (mwt->mode == MMC_HS_400_ES) {
+				err = mmc_select_hs400es(mmc);
+				if (err) {
+					printf("Select HS400ES failed %d\n",
+					       err);
+					goto error;
+				}
 			} else {
 				/* configure the bus speed (card) */
 				err = mmc_set_card_speed(mmc, mwt->mode, false);
diff --git a/include/mmc.h b/include/mmc.h
index 0ef891f5c2..46422f41a4 100644
--- a/include/mmc.h
+++ b/include/mmc.h
@@ -65,6 +65,7 @@
 #define MMC_MODE_DDR_52MHz	MMC_CAP(MMC_DDR_52)
 #define MMC_MODE_HS200		MMC_CAP(MMC_HS_200)
 #define MMC_MODE_HS400		MMC_CAP(MMC_HS_400)
+#define MMC_MODE_HS400_ES	MMC_CAP(MMC_HS_400_ES)
 
 #define MMC_CAP_NONREMOVABLE	BIT(14)
 #define MMC_CAP_NEEDS_POLL	BIT(15)
@@ -223,6 +224,7 @@ static inline bool mmc_is_tuning_cmd(uint cmdidx)
 #define EXT_CSD_BOOT_BUS_WIDTH		177
 #define EXT_CSD_PART_CONF		179	/* R/W */
 #define EXT_CSD_BUS_WIDTH		183	/* R/W */
+#define EXT_CSD_STROBE_SUPPORT		184	/* R/W */
 #define EXT_CSD_HS_TIMING		185	/* R/W */
 #define EXT_CSD_REV			192	/* RO */
 #define EXT_CSD_CARD_TYPE		196	/* RO */
@@ -266,11 +268,13 @@ static inline bool mmc_is_tuning_cmd(uint cmdidx)
 #define EXT_CSD_DDR_BUS_WIDTH_4	5	/* Card is in 4 bit DDR mode */
 #define EXT_CSD_DDR_BUS_WIDTH_8	6	/* Card is in 8 bit DDR mode */
 #define EXT_CSD_DDR_FLAG	BIT(2)	/* Flag for DDR mode */
+#define EXT_CSD_BUS_WIDTH_STROBE BIT(7)	/* Enhanced strobe mode */
 
 #define EXT_CSD_TIMING_LEGACY	0	/* no high speed */
 #define EXT_CSD_TIMING_HS	1	/* HS */
 #define EXT_CSD_TIMING_HS200	2	/* HS200 */
 #define EXT_CSD_TIMING_HS400	3	/* HS400 */
+#define EXT_CSD_DRV_STR_SHIFT	4	/* Driver Strength shift */
 
 #define EXT_CSD_BOOT_ACK_ENABLE			(1 << 6)
 #define EXT_CSD_BOOT_PARTITION_ENABLE		(1 << 3)
@@ -457,6 +461,11 @@ struct dm_mmc_ops {
 	 * @return 0 if dat0 is in the target state, -ve on error
 	 */
 	int (*wait_dat0)(struct udevice *dev, int state, int timeout);
+
+#if CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)
+	/* set_enhanced_strobe() - set HS400 enhanced strobe */
+	int (*set_enhanced_strobe)(struct udevice *dev);
+#endif
 };
 
 #define mmc_get_ops(dev)        ((struct dm_mmc_ops *)(dev)->driver->ops)
@@ -475,6 +484,7 @@ int mmc_getcd(struct mmc *mmc);
 int mmc_getwp(struct mmc *mmc);
 int mmc_execute_tuning(struct mmc *mmc, uint opcode);
 int mmc_wait_dat0(struct mmc *mmc, int state, int timeout);
+int mmc_set_enhanced_strobe(struct mmc *mmc);
 
 #else
 struct mmc_ops {
@@ -520,6 +530,7 @@ enum bus_mode {
 	UHS_SDR104,
 	MMC_HS_200,
 	MMC_HS_400,
+	MMC_HS_400_ES,
 	MMC_MODES_END
 };
 
@@ -538,6 +549,10 @@ static inline bool mmc_is_mode_ddr(enum bus_mode mode)
 	else if (mode == MMC_HS_400)
 		return true;
 #endif
+#if CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)
+	else if (mode == MMC_HS_400_ES)
+		return true;
+#endif
 	else
 		return false;
 }