mmc: sdhci: Add a callback to select drive strength

Add a callbak to let host drivers select drive
strength.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci.c

@@ -2048,6 +2048,18 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
 	return err;
 }
 
+static int sdhci_select_drive_strength(struct mmc_card *card,
+				       unsigned int max_dtr, int host_drv,
+				       int card_drv, int *drv_type)
+{
+	struct sdhci_host *host = mmc_priv(card->host);
+
+	if (!host->ops->select_drive_strength)
+		return 0;
+
+	return host->ops->select_drive_strength(host, card, max_dtr, host_drv,
+						card_drv, drv_type);
+}
 
 static void sdhci_enable_preset_value(struct sdhci_host *host, bool enable)
 {
@@ -2192,6 +2204,7 @@ static const struct mmc_host_ops sdhci_ops = {
 	.start_signal_voltage_switch	= sdhci_start_signal_voltage_switch,
 	.prepare_hs400_tuning		= sdhci_prepare_hs400_tuning,
 	.execute_tuning			= sdhci_execute_tuning,
+	.select_drive_strength		= sdhci_select_drive_strength,
 	.card_event			= sdhci_card_event,
 	.card_busy	= sdhci_card_busy,
 };

drivers/mmc/host/sdhci.h

@@ -538,6 +538,10 @@ struct sdhci_ops {
 	void	(*platform_init)(struct sdhci_host *host);
 	void    (*card_event)(struct sdhci_host *host);
 	void	(*voltage_switch)(struct sdhci_host *host);
+	int	(*select_drive_strength)(struct sdhci_host *host,
+					 struct mmc_card *card,
+					 unsigned int max_dtr, int host_drv,
+					 int card_drv, int *drv_type);
 };
 
 #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS