mmc: add hs400 enhanced strobe support for mmc subsystem

HS400 enhanced strobe is a new feature introduced by eMMC
spec 5.1, let's implement it and enjoy it!

please note that currently I have no much bandwith to split this
big patch into patchset. So please use, test and applied! Thanks.

Change-Id: I874f18a617a1b69e3ff56f5c134feb817b6985b9
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>

3 files changed, 82 insertions, 8 deletions

diff --git a/drivers/mmc/core/bus.c b/drivers/mmc/core/bus.c
index 972ff844cf5a..c40d700d424d 100644
--- a/drivers/mmc/core/bus.c
+++ b/drivers/mmc/core/bus.c
@@ -332,12 +332,13 @@ int mmc_add_card(struct mmc_card *card)
 			mmc_card_ddr52(card) ? "DDR " : "",
 			type);
 	} else {
-		pr_info("%s: new %s%s%s%s%s card at address %04x\n",
+		pr_info("%s: new %s%s%s%s%s%s card at address %04x\n",
 			mmc_hostname(card->host),
 			mmc_card_uhs(card) ? "ultra high speed " :
 			(mmc_card_hs(card) ? "high speed " : ""),
 			mmc_card_hs400(card) ? "HS400 " :
 			(mmc_card_hs200(card) ? "HS200 " : ""),
+			mmc_card_hs400es(card) ? "Enhanced strobe " : "",
 			mmc_card_ddr52(card) ? "DDR " : "",
 			uhs_bus_speed_mode, type, card->rca);
 	}
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 871989e7c228..71bb2372f71d 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -289,6 +289,8 @@ int mmc_of_parse(struct mmc_host *host)
 		host->caps2 |= MMC_CAP2_HS400_1_8V | MMC_CAP2_HS200_1_8V_SDR;
 	if (of_property_read_bool(np, "mmc-hs400-1_2v"))
 		host->caps2 |= MMC_CAP2_HS400_1_2V | MMC_CAP2_HS200_1_2V_SDR;
+	if (of_property_read_bool(np, "mmc-hs400-enhanced-strobe"))
+		host->caps2 |= MMC_CAP2_HS400_ENHANCED_STROBE;
 
 	if (of_property_read_bool(np, "supports-sd"))
 		host->restrict_caps |= RESTRICT_CARD_TYPE_SD;
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 3d5087b03999..94bde1d5dae8 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -235,6 +235,12 @@ static void mmc_select_card_type(struct mmc_card *card)
 		avail_type |= EXT_CSD_CARD_TYPE_HS400_1_2V;
 	}
 
+	if ((caps2 & MMC_CAP2_HS400_ENHANCED_STROBE) &&
+		card->ext_csd.strobe_support &&
+		((card_type & EXT_CSD_CARD_TYPE_HS400_1_2V) ||
+		(card_type & EXT_CSD_CARD_TYPE_HS400_1_8V)))
+		avail_type |= EXT_CSD_CARD_TYPE_HS400ES;
+
 	card->ext_csd.hs_max_dtr = hs_max_dtr;
 	card->ext_csd.hs200_max_dtr = hs200_max_dtr;
 	card->mmc_avail_type = avail_type;
@@ -383,6 +389,13 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
 			mmc_card_set_blockaddr(card);
 	}
 
+	/*
+	 * Enhance Strobe is supported since v5.1 which rev should be
+	 * 8 but some eMMC devices can support it with rev 7. So handle
+	 * Enhance Strobe here.
+	 */
+	card->ext_csd.strobe_support = ext_csd[EXT_CSD_STROBE_SUPPORT];
+
 	card->ext_csd.raw_card_type = ext_csd[EXT_CSD_CARD_TYPE];
 	mmc_select_card_type(card);
 
@@ -1062,10 +1075,11 @@ static int mmc_select_hs400(struct mmc_card *card)
 	u8 val;
 
 	/*
-	 * HS400 mode requires 8-bit bus width
+	 * HS400(ES) mode requires 8-bit bus width
 	 */
-	if (!(card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 &&
-	      host->ios.bus_width == MMC_BUS_WIDTH_8))
+	if (!(((card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400) ||
+		(card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES)) &&
+		host->ios.bus_width == MMC_BUS_WIDTH_8))
 		return 0;
 
 	if (host->caps & MMC_CAP_WAIT_WHILE_BUSY)
@@ -1097,9 +1111,26 @@ static int mmc_select_hs400(struct mmc_card *card)
 	}
 
 	/* Switch card to DDR */
+	val = EXT_CSD_DDR_BUS_WIDTH_8;
+	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES) {
+		val |= EXT_CSD_BUS_WIDTH_STROBE;
+		/*
+		 * Make sure we are in non-enhanced strobe mode before we
+		 * actually enable it in ext_csd.
+		 */
+		if (host->ops->prepare_enhanced_strobe)
+			err = host->ops->prepare_enhanced_strobe(host, false);
+
+		if (err) {
+			pr_err("%s: unprepare_enhanced strobe failed, err:%d\n",
+				mmc_hostname(host), err);
+			return err;
+		}
+	}
+
 	err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
 			 EXT_CSD_BUS_WIDTH,
-			 EXT_CSD_DDR_BUS_WIDTH_8,
+			 val,
 			 card->ext_csd.generic_cmd6_time);
 	if (err) {
 		pr_err("%s: switch to bus width for hs400 failed, err:%d\n",
@@ -1124,6 +1155,35 @@ static int mmc_select_hs400(struct mmc_card *card)
 	mmc_set_timing(host, MMC_TIMING_MMC_HS400);
 	mmc_set_bus_speed(card);
 
+	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES) {
+		/* Controller enable enhanced strobe function */
+		if (host->ops->prepare_enhanced_strobe)
+			err = host->ops->prepare_enhanced_strobe(host, true);
+
+		if (err) {
+			pr_err("%s: prepare enhanced strobe failed, err:%d\n",
+				mmc_hostname(host), err);
+			return err;
+		}
+
+		/*
+		 * After switching to hs400 enhanced strobe mode, we expect to
+		 * verify whether it works or not. If controller can't handle
+		 * bus width test, compare ext_csd previously read in 1 bit mode
+		 * against ext_csd at new bus width
+		 */
+		if (!(host->caps & MMC_CAP_BUS_WIDTH_TEST))
+			err = mmc_compare_ext_csds(card, MMC_BUS_WIDTH_8);
+		else
+			err = mmc_bus_test(card, MMC_BUS_WIDTH_8);
+
+		if (err) {
+			pr_warn("%s: switch to enhanced strobe failed\n",
+				mmc_hostname(host));
+			return err;
+		}
+	}
+
 	if (!send_status) {
 		err = mmc_switch_status(card);
 		if (err)
@@ -1297,7 +1357,8 @@ err:
 }
 
 /*
- * Activate High Speed or HS200 mode if supported.
+ * Activate High Speed or HS200 mode if supported. For HS400
+ * with enhanced strobe mode, we should activate High Speed.
  */
 static int mmc_select_timing(struct mmc_card *card)
 {
@@ -1306,7 +1367,9 @@ static int mmc_select_timing(struct mmc_card *card)
 	if (!mmc_can_ext_csd(card))
 		goto bus_speed;
 
-	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
+	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES)
+		err = mmc_select_hs(card);
+	else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
 		err = mmc_select_hs200(card);
 	else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
 		err = mmc_select_hs(card);
@@ -1577,7 +1640,15 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
 	} else if (mmc_card_hs(card)) {
 		/* Select the desired bus width optionally */
 		err = mmc_select_bus_width(card);
-		if (!IS_ERR_VALUE(err)) {
+		if (IS_ERR_VALUE(err))
+			goto free_card;
+
+		if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES) {
+			/* Directly from HS to HS400-ES */
+			err = mmc_select_hs400(card);
+			if (err)
+				goto free_card;
+		} else {
 			err = mmc_select_hs_ddr(card);
 			if (err)
 				goto free_card;