arm:use the 4 bit mmc data bus if supported by the card.

Change-Id: I55de05db23ad1766e5faec93252e8410cbf59001

diff --git a/drivers/mmc/mmchost_mmchs.c b/drivers/mmc/mmchost_mmchs.c
index 801b84ecbd9caf57ba0835eb820322547879da32..01aadfd7d7cbb61d8a4e7a52e735a9f364dfffd5 100644 (file)
--- a/drivers/mmc/mmchost_mmchs.c
+++ b/drivers/mmc/mmchost_mmchs.c
@@ -810,6 +810,75 @@ select_card(struct sd_card_regs *card)
        }
        return 0;
 }
+
+int
+card_scr(struct sd_card_regs *card)
+{
+       uint8_t buffer[8];      /* 64 bits */
+       uint8_t *p;
+       int c;
+       /* the SD CARD configuration register. This is an additional register
+        * next to the Card Specific register containing additional data we
+        * need */
+       struct mmc_command command;
+
+       log_trace(&log, "Read card scr\n");
+       /* send_csd -> r2 response */
+       command.cmd = SD_APP_SEND_SCR;
+       command.resp_type = RESP_LEN_48;
+       command.args = 0xaaaaaaaa;
+       command.data = buffer;
+       command.data_len = 8;
+
+       if (mmc_send_app_cmd(card, &command)) {
+               return 1;
+       }
+
+       p = (uint8_t *) card->scr;
+
+       /* hussle */
+       for (c = 7; c >= 0; c--) {
+               *p++ = buffer[c];
+       }
+
+       if (!SCR_SD_BUS_WIDTHS(card->scr) & SCR_SD_BUS_WIDTHS_4BIT) {
+               /* it would be very weird not to support 4 bits access */
+               log_warn(&log, "4 bit access not supported\n");
+       }
+
+       log_trace(&log, "1 bit bus width %ssupported\n",
+           (SCR_SD_BUS_WIDTHS(card->scr) & SCR_SD_BUS_WIDTHS_1BIT) ? "" :
+           "un");
+       log_trace(&log, "4 bit bus width %ssupported\n",
+           (SCR_SD_BUS_WIDTHS(card->scr) & SCR_SD_BUS_WIDTHS_4BIT) ? "" :
+           "un");
+
+       return 0;
+}
+
+int
+enable_4bit_mode(struct sd_card_regs *card)
+{
+       struct mmc_command command;
+
+       if (SCR_SD_BUS_WIDTHS(card->scr) & SCR_SD_BUS_WIDTHS_4BIT) {
+               /* set transfer width */
+               command.cmd = SD_APP_SET_BUS_WIDTH;
+               command.resp_type = RESP_LEN_48;
+               command.args = 2;       /* 4 bits */
+
+               if (mmc_send_app_cmd(card, &command)) {
+                       log_warn(&log,
+                           "SD-card does not support 4 bit transfer\n");
+                       return 1;
+               }
+               /* now configure the controller to use 4 bit access */
+               set32(base_address + MMCHS_SD_HCTL, MMCHS_SD_HCTL_DTW,
+                   MMCHS_SD_HCTL_DTW_4BIT);
+       }
+       return 0;
+}
+
 int
 read_single_block(struct sd_card_regs *card,
     uint32_t blknr, unsigned char *buf)
@@ -929,6 +998,17 @@ mmchs_card_initialize(struct sd_slot *slot)
                return NULL;
        }
 
+       if (card_scr(&slot->card.regs)) {
+               log_warn(&log,
+                   "failed to read scr (card additional specific data)\n");
+               return NULL;
+       }
+
+       if (enable_4bit_mode(&slot->card.regs)) {
+               log_warn(&log, "failed to configure 4 bit access mode\n");
+               return NULL;
+       }
+
        if (SD_CSD_READ_BL_LEN(slot->card.regs.csd) != 0x09) {
                /* for CSD version 2.0 the value is fixed to 0x09 and means a
                 * block size of 512 */
@@ -986,6 +1066,10 @@ mmchs_card_release(struct sd_card *card)
        card->state = SD_MODE_UNINITIALIZED;
        /* TODO:Set card state */
 
+       /* now configure the controller to use 4 bit access */
+       set32(base_address + MMCHS_SD_HCTL, MMCHS_SD_HCTL_DTW,
+           MMCHS_SD_HCTL_DTW_1BIT);
+
        return OK;
 }