mmc: core: Add host specific tuning support for eMMC HS400 mode

This adds a ->execute_hs400_tuning() host callback to enable optional
support for host specific tuning for eMMC HS400 mode. Additionally, share
mmc_get_ext_csd() through the public host headerfile, to allow it to be
used by the host drivers, which is needed to support the HS400 tuning.
Signed-off-by: Wenbin Mei <wenbin.mei@mediatek.com>
Link: https://lore.kernel.org/r/20210917124803.22871-3-wenbin.mei@mediatek.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/mmc.c

@@ -1224,6 +1224,14 @@ static int mmc_select_hs400(struct mmc_card *card)
 	mmc_set_timing(host, MMC_TIMING_MMC_HS400);
 	mmc_set_bus_speed(card);
 
+	if (host->ops->execute_hs400_tuning) {
+		mmc_retune_disable(host);
+		err = host->ops->execute_hs400_tuning(host, card);
+		mmc_retune_enable(host);
+		if (err)
+			goto out_err;
+	}
+
 	if (host->ops->hs400_complete)
 		host->ops->hs400_complete(host);
 

drivers/mmc/core/mmc_ops.h

@@ -38,7 +38,6 @@ 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);
 int mmc_bus_test(struct mmc_card *card, u8 bus_width);
 int mmc_can_ext_csd(struct mmc_card *card);
-int mmc_get_ext_csd(struct mmc_card *card, u8 **new_ext_csd);
 int mmc_switch_status(struct mmc_card *card, bool crc_err_fatal);
 bool mmc_prepare_busy_cmd(struct mmc_host *host, struct mmc_command *cmd,
 			  unsigned int timeout_ms);

include/linux/mmc/host.h

@@ -162,6 +162,9 @@ struct mmc_host_ops {
 	/* Prepare HS400 target operating frequency depending host driver */
 	int	(*prepare_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios);
 
+	/* Execute HS400 tuning depending host driver */
+	int	(*execute_hs400_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);
 
@@ -634,5 +637,6 @@ static inline enum dma_data_direction mmc_get_dma_dir(struct mmc_data *data)
 
 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);
 
 #endif /* LINUX_MMC_HOST_H */