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

The MMC startup process currently handles 4 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>

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 3002b72..822b66b 100644 (file)
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -202,6 +202,7 @@ static int mmc_select_mode(struct mmc *mmc, enum bus_mode mode)
 {
        mmc->selected_mode = mode;
        mmc->tran_speed = mmc_mode2freq(mmc, mode);
+       mmc->ddr_mode = mmc_is_mode_ddr(mode);
        debug("selecting mode %s (freq : %d MHz)\n", mmc_mode_name(mode),
              mmc->tran_speed / 1000000);
        return 0;
@@ -605,11 +606,47 @@ int mmc_switch(struct mmc *mmc, u8 set, u8 index, u8 value)
 
 }
 
-static int mmc_change_freq(struct mmc *mmc)
+static int mmc_set_card_speed(struct mmc *mmc, enum bus_mode mode)
 {
-       ALLOC_CACHE_ALIGN_BUFFER(u8, ext_csd, MMC_MAX_BLOCK_LEN);
-       char cardtype;
        int err;
+       int speed_bits;
+
+       ALLOC_CACHE_ALIGN_BUFFER(u8, test_csd, MMC_MAX_BLOCK_LEN);
+
+       switch (mode) {
+       case MMC_HS:
+       case MMC_HS_52:
+       case MMC_DDR_52:
+               speed_bits = EXT_CSD_TIMING_HS;
+       case MMC_LEGACY:
+               speed_bits = EXT_CSD_TIMING_LEGACY;
+               break;
+       default:
+               return -EINVAL;
+       }
+       err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_HS_TIMING,
+                        speed_bits);
+       if (err)
+               return err;
+
+       if ((mode == MMC_HS) || (mode == MMC_HS_52)) {
+               /* Now check to see that it worked */
+               err = mmc_send_ext_csd(mmc, test_csd);
+               if (err)
+                       return err;
+
+               /* No high-speed support */
+               if (!test_csd[EXT_CSD_HS_TIMING])
+                       return -ENOTSUPP;
+       }
+
+       return 0;
+}
+
+static int mmc_get_capabilities(struct mmc *mmc)
+{
+       u8 *ext_csd = mmc->ext_csd;
+       char cardtype;
 
        mmc->card_caps = MMC_MODE_1BIT;
 
@@ -620,38 +657,23 @@ static int mmc_change_freq(struct mmc *mmc)
        if (mmc->version < MMC_VERSION_4)
                return 0;
 
-       mmc->card_caps |= MMC_MODE_4BIT | MMC_MODE_8BIT;
-
-       err = mmc_send_ext_csd(mmc, ext_csd);
+       if (!ext_csd) {
+               printf("No ext_csd found!\n"); /* this should enver happen */
+               return -ENOTSUPP;
+       }
 
-       if (err)
-               return err;
+       mmc->card_caps |= MMC_MODE_4BIT | MMC_MODE_8BIT;
 
        cardtype = ext_csd[EXT_CSD_CARD_TYPE] & 0xf;
 
-       err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_HS_TIMING, 1);
-
-       if (err)
-               return err;
-
-       /* Now check to see that it worked */
-       err = mmc_send_ext_csd(mmc, ext_csd);
-
-       if (err)
-               return err;
-
-       /* No high-speed support */
-       if (!ext_csd[EXT_CSD_HS_TIMING])
-               return 0;
-
        /* High Speed is set, there are two types: 52MHz and 26MHz */
        if (cardtype & EXT_CSD_CARD_TYPE_52) {
-               if (cardtype & EXT_CSD_CARD_TYPE_DDR_1_8V)
+               if (cardtype & EXT_CSD_CARD_TYPE_DDR_52)
                        mmc->card_caps |= MMC_MODE_DDR_52MHz;
-               mmc->card_caps |= MMC_MODE_HS_52MHz | MMC_MODE_HS;
-       } else {
-               mmc->card_caps |= MMC_MODE_HS;
+               mmc->card_caps |= MMC_MODE_HS_52MHz;
        }
+       if (cardtype & EXT_CSD_CARD_TYPE_26)
+               mmc->card_caps |= MMC_MODE_HS;
 
        return 0;
 }
@@ -1334,33 +1356,60 @@ static int mmc_read_and_compare_ext_csd(struct mmc *mmc)
        return -EBADMSG;
 }
 
-static int mmc_select_bus_freq_width(struct mmc *mmc)
+static const struct mode_width_tuning mmc_modes_by_pref[] = {
+       {
+               .mode = MMC_HS_200,
+               .widths = MMC_MODE_8BIT | MMC_MODE_4BIT,
+       },
+       {
+               .mode = MMC_DDR_52,
+               .widths = MMC_MODE_8BIT | MMC_MODE_4BIT,
+       },
+       {
+               .mode = MMC_HS_52,
+               .widths = MMC_MODE_8BIT | MMC_MODE_4BIT | MMC_MODE_1BIT,
+       },
+       {
+               .mode = MMC_HS,
+               .widths = MMC_MODE_8BIT | MMC_MODE_4BIT | MMC_MODE_1BIT,
+       },
+       {
+               .mode = MMC_LEGACY,
+               .widths = MMC_MODE_8BIT | MMC_MODE_4BIT | MMC_MODE_1BIT,
+       }
+};
+
+#define for_each_mmc_mode_by_pref(caps, mwt) \
+       for (mwt = mmc_modes_by_pref;\
+           mwt < mmc_modes_by_pref + ARRAY_SIZE(mmc_modes_by_pref);\
+           mwt++) \
+               if (caps & MMC_CAP(mwt->mode))
+
+static const struct ext_csd_bus_width {
+       uint cap;
+       bool is_ddr;
+       uint ext_csd_bits;
+} ext_csd_bus_width[] = {
+       {MMC_MODE_8BIT, true, EXT_CSD_DDR_BUS_WIDTH_8},
+       {MMC_MODE_4BIT, true, EXT_CSD_DDR_BUS_WIDTH_4},
+       {MMC_MODE_8BIT, false, EXT_CSD_BUS_WIDTH_8},
+       {MMC_MODE_4BIT, false, EXT_CSD_BUS_WIDTH_4},
+       {MMC_MODE_1BIT, false, EXT_CSD_BUS_WIDTH_1},
+};
+
+#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);\
+           ecbv++) \
+               if ((ddr == ecbv->is_ddr) && (caps & ecbv->cap))
+
+static int mmc_select_mode_and_width(struct mmc *mmc)
 {
-       /* An array of possible bus widths in order of preference */
-       static const unsigned int ext_csd_bits[] = {
-               EXT_CSD_DDR_BUS_WIDTH_8,
-               EXT_CSD_DDR_BUS_WIDTH_4,
-               EXT_CSD_BUS_WIDTH_8,
-               EXT_CSD_BUS_WIDTH_4,
-               EXT_CSD_BUS_WIDTH_1,
-       };
-       /* An array to map CSD bus widths to host cap bits */
-       static const unsigned int ext_to_hostcaps[] = {
-               [EXT_CSD_DDR_BUS_WIDTH_4] =
-                       MMC_MODE_DDR_52MHz | MMC_MODE_4BIT,
-               [EXT_CSD_DDR_BUS_WIDTH_8] =
-                       MMC_MODE_DDR_52MHz | MMC_MODE_8BIT,
-               [EXT_CSD_BUS_WIDTH_4] = MMC_MODE_4BIT,
-               [EXT_CSD_BUS_WIDTH_8] = MMC_MODE_8BIT,
-       };
-       /* An array to map chosen bus width to an integer */
-       static const unsigned int widths[] = {
-               8, 4, 8, 4, 1,
-       };
        int err;
-       int idx;
+       const struct mode_width_tuning *mwt;
+       const struct ext_csd_bus_width *ecbw;
 
-       err = mmc_change_freq(mmc);
+       err = mmc_get_capabilities(mmc);
        if (err)
                return err;
 
@@ -1376,54 +1425,58 @@ static int mmc_select_bus_freq_width(struct mmc *mmc)
                return -ENOTSUPP;
        }
 
-       for (idx = 0; idx < ARRAY_SIZE(ext_csd_bits); idx++) {
-               unsigned int extw = ext_csd_bits[idx];
-               unsigned int caps = ext_to_hostcaps[extw];
-               /*
-                * If the bus width is still not changed,
-                * don't try to set the default again.
-                * Otherwise, recover from switch attempts
-                * by switching to 1-bit bus width.
-                */
-               if (extw == EXT_CSD_BUS_WIDTH_1 &&
-                   mmc->bus_width == 1) {
-                       err = 0;
-                       break;
-               }
-
-               /*
-                * Check to make sure the card and controller support
-                * these capabilities
-                */
-               if ((mmc->card_caps & caps) != caps)
-                       continue;
-
-               err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
-                                EXT_CSD_BUS_WIDTH, extw);
+       for_each_mmc_mode_by_pref(mmc->card_caps, mwt) {
+               for_each_supported_width(mmc->card_caps & mwt->widths,
+                                        mmc_is_mode_ddr(mwt->mode), ecbw) {
+                       debug("trying mode %s width %d (at %d MHz)\n",
+                             mmc_mode_name(mwt->mode),
+                             bus_width(ecbw->cap),
+                             mmc_mode2freq(mmc, mwt->mode) / 1000000);
+                       /* configure the bus width (card + host) */
+                       err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
+                                   EXT_CSD_BUS_WIDTH,
+                                   ecbw->ext_csd_bits & ~EXT_CSD_DDR_FLAG);
+                       if (err)
+                               goto error;
+                       mmc_set_bus_width(mmc, bus_width(ecbw->cap));
 
-               if (err)
-                       continue;
+                       /* configure the bus speed (card) */
+                       err = mmc_set_card_speed(mmc, mwt->mode);
+                       if (err)
+                               goto error;
+
+                       /*
+                        * configure the bus width AND the ddr mode (card)
+                        * The host side will be taken care of in the next step
+                        */
+                       if (ecbw->ext_csd_bits & EXT_CSD_DDR_FLAG) {
+                               err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
+                                                EXT_CSD_BUS_WIDTH,
+                                                ecbw->ext_csd_bits);
+                               if (err)
+                                       goto error;
+                       }
 
-               mmc->ddr_mode = (caps & MMC_MODE_DDR_52MHz) ? 1 : 0;
-               mmc_set_bus_width(mmc, widths[idx]);
+                       /* configure the bus mode (host) */
+                       mmc_select_mode(mmc, mwt->mode);
+                       mmc_set_clock(mmc, mmc->tran_speed);
 
-               err = mmc_read_and_compare_ext_csd(mmc);
-               if (!err)
-                       break;
+                       /* do a transfer to check the configuration */
+                       err = mmc_read_and_compare_ext_csd(mmc);
+                       if (!err)
+                               return 0;
+error:
+                       /* if an error occured, revert to a safer bus mode */
+                       mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
+                                  EXT_CSD_BUS_WIDTH, EXT_CSD_BUS_WIDTH_1);
+                       mmc_select_mode(mmc, MMC_LEGACY);
+                       mmc_set_bus_width(mmc, 1);
+               }
        }
 
-       if (err)
-               return err;
-
-       if (mmc->card_caps & MMC_MODE_HS_52MHz) {
-               if (mmc->ddr_mode)
-                       mmc_select_mode(mmc, MMC_DDR_52);
-               else
-                       mmc_select_mode(mmc, MMC_HS_52);
-       } else if (mmc->card_caps & MMC_MODE_HS)
-               mmc_select_mode(mmc, MMC_HS);
+       printf("unable to select a mode\n");
 
-       return err;
+       return -ENOTSUPP;
 }
 
 static int mmc_startup_v4(struct mmc *mmc)
@@ -1762,7 +1815,7 @@ static int mmc_startup(struct mmc *mmc)
        if (IS_SD(mmc))
                err = sd_select_mode_and_width(mmc);
        else
-               err = mmc_select_bus_freq_width(mmc);
+               err = mmc_select_mode_and_width(mmc);
 
        if (err)
                return err;

diff --git a/include/mmc.h b/include/mmc.h
index 9fe6a87..988bf17 100644 (file)
--- a/include/mmc.h
+++ b/include/mmc.h
@@ -215,7 +215,10 @@
 #define EXT_CSD_BUS_WIDTH_8    2       /* Card is in 8 bit mode */
 #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_TIMING_LEGACY  0       /* no high speed */
+#define EXT_CSD_TIMING_HS      1       /* HS */
 #define EXT_CSD_BOOT_ACK_ENABLE                        (1 << 6)
 #define EXT_CSD_BOOT_PARTITION_ENABLE          (1 << 3)
 #define EXT_CSD_PARTITION_ACCESS_ENABLE                (1 << 0)
@@ -429,6 +432,14 @@ enum bus_mode {
 const char *mmc_mode_name(enum bus_mode mode);
 void mmc_dump_capabilities(const char *text, uint caps);
 
+static inline bool mmc_is_mode_ddr(enum bus_mode mode)
+{
+       if ((mode == MMC_DDR_52) || (mode == UHS_DDR50))
+               return true;
+       else
+               return false;
+}
+
 /*
  * With CONFIG_DM_MMC enabled, struct mmc can be accessed from the MMC device
  * with mmc_get_mmc_dev().