mmc: core: add support for eMMC Dual Data Rate

eMMC voltage change not required for 1.8V.  3.3V and 1.8V vcc
are capable of doing DDR. vccq of 1.8v is not required.

Signed-off-by: Philip Rakity <prakity@marvell.com>
Reviewed-by: Arindam Nath <arindam.nath@amd.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 30 insertions, 5 deletions

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index a2c795e8f9dd..0433fe66cbad 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -20,6 +20,7 @@
 #include "core.h"
 #include "bus.h"
 #include "mmc_ops.h"
+#include "sd_ops.h"
 
 static const unsigned int tran_exp[] = {
         10000,          100000,         1000000,        10000000,
@@ -633,10 +634,14 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
          */
         if (mmc_card_highspeed(card)) {
                 if ((card->ext_csd.card_type & EXT_CSD_CARD_TYPE_DDR_1_8V)
-                        && (host->caps & (MMC_CAP_1_8V_DDR)))
+                        && ((host->caps & (MMC_CAP_1_8V_DDR |
+                             MMC_CAP_UHS_DDR50))
+                                == (MMC_CAP_1_8V_DDR | MMC_CAP_UHS_DDR50)))
                                 ddr = MMC_1_8V_DDR_MODE;
                 else if ((card->ext_csd.card_type & EXT_CSD_CARD_TYPE_DDR_1_2V)
-                        && (host->caps & (MMC_CAP_1_2V_DDR)))
+                        && ((host->caps & (MMC_CAP_1_2V_DDR |
+                             MMC_CAP_UHS_DDR50))
+                                == (MMC_CAP_1_2V_DDR | MMC_CAP_UHS_DDR50)))
                                 ddr = MMC_1_2V_DDR_MODE;
         }
 
@@ -670,8 +675,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
                                          ext_csd_bits[idx][0],
                                          0);
                         if (!err) {
-                                mmc_set_bus_width_ddr(card->host,
-                                                      bus_width, MMC_SDR_MODE);
+                                mmc_set_bus_width(card->host, bus_width);
                                 /*
                                  * If controller can't handle bus width test,
                                  * use the highest bus width to maintain
@@ -697,8 +701,29 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
                                 1 << bus_width, ddr);
                         goto free_card;
                 } else if (ddr) {
+                        /*
+                         * eMMC cards can support 3.3V to 1.2V i/o (vccq)
+                         * signaling.
+                         *
+                         * EXT_CSD_CARD_TYPE_DDR_1_8V means 3.3V or 1.8V vccq.
+                         *
+                         * 1.8V vccq at 3.3V core voltage (vcc) is not required
+                         * in the JEDEC spec for DDR.
+                         *
+                         * Do not force change in vccq since we are obviously
+                         * working and no change to vccq is needed.
+                         *
+                         * WARNING: eMMC rules are NOT the same as SD DDR
+                         */
+                        if (ddr == EXT_CSD_CARD_TYPE_DDR_1_2V) {
+                                err = mmc_set_signal_voltage(host,
+                                        MMC_SIGNAL_VOLTAGE_120, 0);
+                                if (err)
+                                        goto err;
+                        }
                         mmc_card_set_ddr_mode(card);
-                        mmc_set_bus_width_ddr(card->host, bus_width, ddr);
+                        mmc_set_timing(card->host, MMC_TIMING_UHS_DDR50);
+                        mmc_set_bus_width(card->host, bus_width);
                 }
         }