mmc: core: Add host specific tuning support for SD HS mode

To support the need for host specific tuning for SD high-speed mode, let's
add two new optional callbacks, ->prepare|execute_sd_hs_tuning() and let's
call them when switching into the SD high-speed mode.

Note that, during the tuning process it's also needed for host drivers to
send commands to the SD card to verify that the tuning process succeeds.
Therefore, let's also share the corresponding functions from the core to
allow this.

Signed-off-by: Wenchao Chen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[Ulf: Dropped unnecessary function declarations and updated the commit msg]
Signed-off-by: Ulf Hansson <[e-mail]>

drivers/mmc/core/mmc_ops.h

···
 		       u32 args, void *buf, unsigned len);
 int mmc_send_csd(struct mmc_card *card, u32 *csd);
 int __mmc_send_status(struct mmc_card *card, u32 *status, unsigned int retries);
-int mmc_send_status(struct mmc_card *card, u32 *status);
 int mmc_send_cid(struct mmc_host *host, u32 *cid);
 int mmc_spi_read_ocr(struct mmc_host *host, int highcap, u32 *ocrp);
 int mmc_spi_set_crc(struct mmc_host *host, int use_crc);

drivers/mmc/core/sd.c

···
 		 */
 		mmc_set_clock(host, mmc_sd_get_max_clock(card));
 
+		if (host->ios.timing == MMC_TIMING_SD_HS &&
+			host->ops->prepare_sd_hs_tuning) {
+			err = host->ops->prepare_sd_hs_tuning(host, card);
+			if (err)
+				goto free_card;
+		}
+
 		/*
 		 * Switch to wider bus (if supported).
 		 */
···
 				goto free_card;
 
 			mmc_set_bus_width(host, MMC_BUS_WIDTH_4);
+		}
+
+		if (host->ios.timing == MMC_TIMING_SD_HS &&
+			host->ops->execute_sd_hs_tuning) {
+			err = host->ops->execute_sd_hs_tuning(host, card);
+			if (err)
+				goto free_card;
 		}
 	}
 cont:

drivers/mmc/core/sd_ops.c

···
 	return mmc_send_adtc_data(card, card->host, SD_SWITCH, cmd_args, resp,
 				  64);
 }
+EXPORT_SYMBOL_GPL(mmc_sd_switch);
 
 int mmc_app_sd_status(struct mmc_card *card, void *ssr)
 {

drivers/mmc/core/sd_ops.h

···
 int mmc_send_if_cond_pcie(struct mmc_host *host, u32 ocr);
 int mmc_send_relative_addr(struct mmc_host *host, unsigned int *rca);
 int mmc_app_send_scr(struct mmc_card *card);
-int mmc_sd_switch(struct mmc_card *card, int mode, int group,
-	u8 value, u8 *resp);
 int mmc_app_sd_status(struct mmc_card *card, void *ssr);
 int mmc_app_cmd(struct mmc_host *host, struct mmc_card *card);
 

include/linux/mmc/host.h

···
 	/* Execute HS400 tuning depending host driver */
 	int	(*execute_hs400_tuning)(struct mmc_host *host, struct mmc_card *card);
 
+	/* Optional callback to prepare for SD high-speed tuning */
+	int	(*prepare_sd_hs_tuning)(struct mmc_host *host, struct mmc_card *card);
+
+	/* Optional callback to execute SD high-speed tuning */
+	int	(*execute_sd_hs_tuning)(struct mmc_host *host, struct mmc_card *card);
+
 	/* Prepare switch to DDR during the HS400 init sequence */
 	int	(*hs400_prepare_ddr)(struct mmc_host *host);
 
···
 	host->err_stats[stat] += 1;
 }
 
+int mmc_sd_switch(struct mmc_card *card, int mode, int group, u8 value, u8 *resp);
+int mmc_send_status(struct mmc_card *card, u32 *status);
 int mmc_send_tuning(struct mmc_host *host, u32 opcode, int *cmd_error);
 int mmc_send_abort_tuning(struct mmc_host *host, u32 opcode);
 int mmc_get_ext_csd(struct mmc_card *card, u8 **new_ext_csd);