mmc: add a mmc_hs400_prepare_ddr() interface

Add a mmc_hs400_prepare_ddr() interface for controllers
which needs preparation before switching to DDR mode for
HS400 mode.
Signed-off-by: NYangbo Lu <yangbo.lu@nxp.com>

drivers/mmc/mmc-uclass.c

@@ -142,6 +142,21 @@ int mmc_set_enhanced_strobe(struct mmc *mmc)
 }
 #endif
 
+int dm_mmc_hs400_prepare_ddr(struct udevice *dev)
+{
+	struct dm_mmc_ops *ops = mmc_get_ops(dev);
+
+	if (ops->hs400_prepare_ddr)
+		return ops->hs400_prepare_ddr(dev);
+
+	return 0;
+}
+
+int mmc_hs400_prepare_ddr(struct mmc *mmc)
+{
+	return dm_mmc_hs400_prepare_ddr(mmc->dev);
+}
+
 int dm_mmc_host_power_cycle(struct udevice *dev)
 {
 	struct dm_mmc_ops *ops = mmc_get_ops(dev);

drivers/mmc/mmc.c

@@ -1993,6 +1993,10 @@ static int mmc_select_hs400(struct mmc *mmc)
 	/* Set back to HS */
 	mmc_set_card_speed(mmc, MMC_HS, true);
 
+	err = mmc_hs400_prepare_ddr(mmc);
+	if (err)
+		return err;
+
 	err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_BUS_WIDTH,
 			 EXT_CSD_BUS_WIDTH_8 | EXT_CSD_DDR_FLAG);
 	if (err)

include/mmc.h

@@ -513,6 +513,14 @@ struct dm_mmc_ops {
 	 * @return maximum number of blocks for this transfer
 	 */
 	int (*get_b_max)(struct udevice *dev, void *dst, lbaint_t blkcnt);
+
+	/**
+	 * hs400_prepare_ddr - prepare to switch to DDR mode
+	 *
+	 * @dev:	Device to check
+	 * @return 0 if success, -ve on error
+	 */
+	int (*hs400_prepare_ddr)(struct udevice *dev);
 };
 
 #define mmc_get_ops(dev)        ((struct dm_mmc_ops *)(dev)->driver->ops)
@@ -540,7 +548,7 @@ int mmc_host_power_cycle(struct mmc *mmc);
 int mmc_deferred_probe(struct mmc *mmc);
 int mmc_reinit(struct mmc *mmc);
 int mmc_get_b_max(struct mmc *mmc, void *dst, lbaint_t blkcnt);
-
+int mmc_hs400_prepare_ddr(struct mmc *mmc);
 #else
 struct mmc_ops {
 	int (*send_cmd)(struct mmc *mmc,
@@ -552,6 +560,11 @@ struct mmc_ops {
 	int (*host_power_cycle)(struct mmc *mmc);
 	int (*get_b_max)(struct mmc *mmc, void *dst, lbaint_t blkcnt);
 };
+
+static inline int mmc_hs400_prepare_ddr(struct mmc *mmc)
+{
+	return 0;
+}
 #endif
 
 struct mmc_config {