mmc: refactor SD startup to make it easier to support new modes

The SDcard startup process currently handles only 2 modes. To make it
easier to add support for more modes, let's make the process more generic
and use a list of the modes to try.
The major functional change is that when a mode fails we try the next one.
Not all modes are tried, only those supported by the card and the host.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/mmc/mmc.c

@@ -237,7 +237,8 @@ int mmc_send_status(struct mmc *mmc, int timeout)
 			    (cmd.response[0] & MMC_STATUS_CURR_STATE) !=
 			     MMC_STATE_PRG)
 				break;
-			else if (cmd.response[0] & MMC_STATUS_MASK) {
+
+			if (cmd.response[0] & MMC_STATUS_MASK) {
 #if !defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_LIBCOMMON_SUPPORT)
 				printf("Status Error: 0x%08X\n",
 					cmd.response[0]);
@@ -610,7 +611,7 @@ static int mmc_change_freq(struct mmc *mmc)
 	char cardtype;
 	int err;
 
-	mmc->card_caps = 0;
+	mmc->card_caps = MMC_MODE_1BIT;
 
 	if (mmc_host_is_spi(mmc))
 		return 0;
@@ -936,7 +937,7 @@ static int sd_switch(struct mmc *mmc, int mode, int group, u8 value, u8 *resp)
 }
 
 
-static int sd_change_freq(struct mmc *mmc)
+static int sd_get_capabilities(struct mmc *mmc)
 {
 	int err;
 	struct mmc_cmd cmd;
@@ -945,7 +946,7 @@ static int sd_change_freq(struct mmc *mmc)
 	struct mmc_data data;
 	int timeout;
 
-	mmc->card_caps = 0;
+	mmc->card_caps = MMC_MODE_1BIT;
 
 	if (mmc_host_is_spi(mmc))
 		return 0;
@@ -1022,26 +1023,53 @@ retry_scr:
 	}
 
 	/* If high-speed isn't supported, we return */
-	if (!(__be32_to_cpu(switch_status[3]) & SD_HIGHSPEED_SUPPORTED))
+	if (__be32_to_cpu(switch_status[3]) & SD_HIGHSPEED_SUPPORTED)
-		return 0;
+		mmc->card_caps |= MMC_CAP(SD_HS);
 
-	/*
+	return 0;
-	 * If the host doesn't support SD_HIGHSPEED, do not switch card to
+}
-	 * HIGHSPEED mode even if the card support SD_HIGHSPPED.
+
-	 * This can avoid furthur problem when the card runs in different
+static int sd_set_card_speed(struct mmc *mmc, enum bus_mode mode)
-	 * mode between the host.
+{
-	 */
+	int err;
-	if (!((mmc->cfg->host_caps & MMC_MODE_HS_52MHz) &&
+
-		(mmc->cfg->host_caps & MMC_MODE_HS)))
+	ALLOC_CACHE_ALIGN_BUFFER(uint, switch_status, 16);
-		return 0;
 
 	err = sd_switch(mmc, SD_SWITCH_SWITCH, 0, 1, (u8 *)switch_status);
-
 	if (err)
 		return err;
 
-	if ((__be32_to_cpu(switch_status[4]) & 0x0f000000) == 0x01000000)
+	if ((__be32_to_cpu(switch_status[4]) & 0x0f000000) != 0x01000000)
-		mmc->card_caps |= MMC_MODE_HS;
+		return -ENOTSUPP;
+
+	return 0;
+}
+
+int sd_select_bus_width(struct mmc *mmc, int w)
+{
+	int err;
+	struct mmc_cmd cmd;
+
+	if ((w != 4) && (w != 1))
+		return -EINVAL;
+
+	cmd.cmdidx = MMC_CMD_APP_CMD;
+	cmd.resp_type = MMC_RSP_R1;
+	cmd.cmdarg = mmc->rca << 16;
+
+	err = mmc_send_cmd(mmc, &cmd, NULL);
+	if (err)
+		return err;
+
+	cmd.cmdidx = SD_CMD_APP_SET_BUS_WIDTH;
+	cmd.resp_type = MMC_RSP_R1;
+	if (w == 4)
+		cmd.cmdarg = 2;
+	else if (w == 1)
+		cmd.cmdarg = 0;
+	err = mmc_send_cmd(mmc, &cmd, NULL);
+	if (err)
+		return err;
 
 	return 0;
 }
@@ -1133,6 +1161,18 @@ static const u8 multipliers[] = {
 	80,
 };
 
+static inline int bus_width(uint cap)
+{
+	if (cap == MMC_MODE_8BIT)
+		return 8;
+	if (cap == MMC_MODE_4BIT)
+		return 4;
+	if (cap == MMC_MODE_1BIT)
+		return 1;
+	printf("invalid bus witdh capability 0x%x\n", cap);
+	return 0;
+}
+
 #if !CONFIG_IS_ENABLED(DM_MMC)
 static void mmc_set_ios(struct mmc *mmc)
 {
@@ -1176,8 +1216,9 @@ void mmc_dump_capabilities(const char *text, uint caps)
 		printf("8, ");
 	if (caps & MMC_MODE_4BIT)
 		printf("4, ");
-	printf("1] modes [");
+	if (caps & MMC_MODE_1BIT)
-
+		printf("1, ");
+	printf("\b\b] modes [");
 	for (mode = MMC_LEGACY; mode < MMC_MODES_END; mode++)
 		if (MMC_CAP(mode) & caps)
 			printf("%s, ", mmc_mode_name(mode));
@@ -1185,47 +1226,81 @@ void mmc_dump_capabilities(const char *text, uint caps)
 }
 #endif
 
-static int sd_select_bus_freq_width(struct mmc *mmc)
+struct mode_width_tuning {
+	enum bus_mode mode;
+	uint widths;
+};
+
+static const struct mode_width_tuning sd_modes_by_pref[] = {
+	{
+		.mode = SD_HS,
+		.widths = MMC_MODE_4BIT | MMC_MODE_1BIT,
+	},
+	{
+		.mode = SD_LEGACY,
+		.widths = MMC_MODE_4BIT | MMC_MODE_1BIT,
+	}
+};
+
+#define for_each_sd_mode_by_pref(caps, mwt) \
+	for (mwt = sd_modes_by_pref;\
+	     mwt < sd_modes_by_pref + ARRAY_SIZE(sd_modes_by_pref);\
+	     mwt++) \
+		if (caps & MMC_CAP(mwt->mode))
+
+static int sd_select_mode_and_width(struct mmc *mmc)
 {
 	int err;
-	struct mmc_cmd cmd;
+	uint widths[] = {MMC_MODE_4BIT, MMC_MODE_1BIT};
+	const struct mode_width_tuning *mwt;
 
-	err = sd_change_freq(mmc);
+	err = sd_get_capabilities(mmc);
 	if (err)
 		return err;
-
 	/* Restrict card's capabilities by what the host can do */
-	mmc->card_caps &= mmc->cfg->host_caps;
+	mmc->card_caps &= (mmc->cfg->host_caps | MMC_MODE_1BIT);
 
-	if (mmc->card_caps & MMC_MODE_4BIT) {
+	for_each_sd_mode_by_pref(mmc->card_caps, mwt) {
-		cmd.cmdidx = MMC_CMD_APP_CMD;
+		uint *w;
-		cmd.resp_type = MMC_RSP_R1;
-		cmd.cmdarg = mmc->rca << 16;
 
-		err = mmc_send_cmd(mmc, &cmd, NULL);
+		for (w = widths; w < widths + ARRAY_SIZE(widths); w++) {
-		if (err)
+			if (*w & mmc->card_caps & mwt->widths) {
-			return err;
+				debug("trying mode %s width %d (at %d MHz)\n",
+				      mmc_mode_name(mwt->mode),
+				      bus_width(*w),
+				      mmc_mode2freq(mmc, mwt->mode) / 1000000);
 
-		cmd.cmdidx = SD_CMD_APP_SET_BUS_WIDTH;
+				/* configure the bus width (card + host) */
-		cmd.resp_type = MMC_RSP_R1;
+				err = sd_select_bus_width(mmc, bus_width(*w));
-		cmd.cmdarg = 2;
+				if (err)
-		err = mmc_send_cmd(mmc, &cmd, NULL);
+					goto error;
-		if (err)
+				mmc_set_bus_width(mmc, bus_width(*w));
-			return err;
 
-		mmc_set_bus_width(mmc, 4);
+				/* configure the bus mode (card) */
+				err = sd_set_card_speed(mmc, mwt->mode);
+				if (err)
+					goto error;
+
+				/* configure the bus mode (host) */
+				mmc_select_mode(mmc, mwt->mode);
+				mmc_set_clock(mmc, mmc->tran_speed);
+
+				err = sd_read_ssr(mmc);
+				if (!err)
+					return 0;
+
+				printf("bad ssr\n");
+
+error:
+				/* revert to a safer bus speed */
+				mmc_select_mode(mmc, SD_LEGACY);
+				mmc_set_clock(mmc, mmc->tran_speed);
+			}
+		}
 	}
 
-	err = sd_read_ssr(mmc);
+	printf("unable to select a mode\n");
-	if (err)
+	return -ENOTSUPP;
-		return err;
-
-	if (mmc->card_caps & MMC_MODE_HS)
-		mmc_select_mode(mmc, SD_HS);
-	else
-		mmc_select_mode(mmc, SD_LEGACY);
-
-	return 0;
 }
 
 /*
@@ -1290,7 +1365,7 @@ static int mmc_select_bus_freq_width(struct mmc *mmc)
 		return err;
 
 	/* Restrict card's capabilities by what the host can do */
-	mmc->card_caps &= mmc->cfg->host_caps;
+	mmc->card_caps &= (mmc->cfg->host_caps | MMC_MODE_1BIT);
 
 	/* Only version 4 of MMC supports wider bus widths */
 	if (mmc->version < MMC_VERSION_4)
@@ -1685,7 +1760,7 @@ static int mmc_startup(struct mmc *mmc)
 		return err;
 
 	if (IS_SD(mmc))
-		err = sd_select_bus_freq_width(mmc);
+		err = sd_select_mode_and_width(mmc);
 	else
 		err = mmc_select_bus_freq_width(mmc);
 

include/mmc.h

@@ -59,6 +59,7 @@
 
 #define MMC_MODE_8BIT		BIT(30)
 #define MMC_MODE_4BIT		BIT(29)
+#define MMC_MODE_1BIT		BIT(28)
 #define MMC_MODE_SPI		BIT(27)