mmc: core: add helpers mmc_regulator_enable/disable_vqmmc

There's a number of drivers (e.g. dw_mmc, meson-gx, mmci, sunxi) using
the same mechanism and a private flag vqmmc_enabled to deal with
enabling/disabling the vqmmc regulator.

Move this to the core and create new helpers mmc_regulator_enable_vqmmc
and mmc_regulator_disable_vqmmc.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/71586432-360f-9b92-17f6-b05a8a971bc2@gmail.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/regulator.c

@@ -274,3 +274,44 @@ int mmc_regulator_get_supply(struct mmc_host *mmc)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(mmc_regulator_get_supply);
+
+/**
+ * mmc_regulator_enable_vqmmc - enable VQMMC regulator for a host
+ * @mmc: the host to regulate
+ *
+ * Returns 0 or errno. Enables the regulator for vqmmc.
+ * Keeps track of the enable status for ensuring that calls to
+ * regulator_enable/disable are balanced.
+ */
+int mmc_regulator_enable_vqmmc(struct mmc_host *mmc)
+{
+	int ret = 0;
+
+	if (!IS_ERR(mmc->supply.vqmmc) && !mmc->vqmmc_enabled) {
+		ret = regulator_enable(mmc->supply.vqmmc);
+		if (ret < 0)
+			dev_err(mmc_dev(mmc), "enabling vqmmc regulator failed\n");
+		else
+			mmc->vqmmc_enabled = true;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mmc_regulator_enable_vqmmc);
+
+/**
+ * mmc_regulator_disable_vqmmc - disable VQMMC regulator for a host
+ * @mmc: the host to regulate
+ *
+ * Returns 0 or errno. Disables the regulator for vqmmc.
+ * Keeps track of the enable status for ensuring that calls to
+ * regulator_enable/disable are balanced.
+ */
+void mmc_regulator_disable_vqmmc(struct mmc_host *mmc)
+{
+	if (!IS_ERR(mmc->supply.vqmmc) && mmc->vqmmc_enabled) {
+		regulator_disable(mmc->supply.vqmmc);
+		mmc->vqmmc_enabled = false;
+	}
+}
+EXPORT_SYMBOL_GPL(mmc_regulator_disable_vqmmc);

include/linux/mmc/host.h

@@ -450,6 +450,7 @@ struct mmc_host {
 	unsigned int		retune_paused:1; /* re-tuning is temporarily disabled */
 	unsigned int		retune_crc_disable:1; /* don't trigger retune upon crc */
 	unsigned int		can_dma_map_merge:1; /* merging can be used */
+	unsigned int		vqmmc_enabled:1; /* vqmmc regulator is enabled */
 
 	int			rescan_disable;	/* disable card detection */
 	int			rescan_entered;	/* used with nonremovable devices */
@@ -598,6 +599,8 @@ static inline int mmc_regulator_set_vqmmc(struct mmc_host *mmc,
 #endif
 
 int mmc_regulator_get_supply(struct mmc_host *mmc);
+int mmc_regulator_enable_vqmmc(struct mmc_host *mmc);
+void mmc_regulator_disable_vqmmc(struct mmc_host *mmc);
 
 static inline int mmc_card_is_removable(struct mmc_host *host)
 {