[PATCH 4/4] mmc: core: Extend support for mmc regulators with a vqmmc2

[Ulf Hansson]

To allow an additional external regulator to be controlled by an mmc host
driver, let's add support for a vqmmc2 regulator to the mmc core.

For an SD UHS-II interface the vqmmc2 regulator may correspond to the so
called vdd2 supply, as described by the SD spec. Initially, only 1.8V is
needed, hence limit the new helper function, mmc_regulator_set_vqmmc2() to
this too.

Note that, to allow for flexibility mmc host drivers need to manage the
enable/disable of the vqmmc2 regulator themselves, while the regulator is
looked up through the common mmc_regulator_get_supply().

Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
---
 drivers/mmc/core/regulator.c | 34 ++++++++++++++++++++++++++++++++++
 include/linux/mmc/host.h     | 11 +++++++++++
 2 files changed, 45 insertions(+)

diff --git a/drivers/mmc/core/regulator.c b/drivers/mmc/core/regulator.c
index 609201a467ef..3c189682797c 100644
--- a/drivers/mmc/core/regulator.c
+++ b/drivers/mmc/core/regulator.c
@@ -223,6 +223,33 @@ int mmc_regulator_set_vqmmc(struct mmc_host *mmc, struct mmc_ios *ios)
 }
 EXPORT_SYMBOL_GPL(mmc_regulator_set_vqmmc);
 
+/**
+ * mmc_regulator_set_vqmmc2 - Set vqmmc2 as per the ios->vqmmc2_voltage
+ * @mmc: The mmc host to regulate
+ * @ios: The io bus settings
+ *
+ * Sets a new voltage level for the vqmmc2 regulator, which may correspond to
+ * the vdd2 regulator for an SD UHS-II interface. This function is expected to
+ * be called by mmc host drivers.
+ *
+ * Returns a negative error code on failure, zero if the voltage level was
+ * changed successfully or a positive value if the level didn't need to change.
+ */
+int mmc_regulator_set_vqmmc2(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+	if (IS_ERR(mmc->supply.vqmmc2))
+		return -EINVAL;
+
+	switch (ios->vqmmc2_voltage) {
+	case MMC_VQMMC2_VOLTAGE_180:
+		return mmc_regulator_set_voltage_if_supported(
+			mmc->supply.vqmmc2, 1700000, 1800000, 1950000);
+	default:
+		return -EINVAL;
+	}
+}
+EXPORT_SYMBOL_GPL(mmc_regulator_set_vqmmc2);
+
 #else
 
 static inline int mmc_regulator_get_ocrmask(struct regulator *supply)
@@ -249,6 +276,7 @@ int mmc_regulator_get_supply(struct mmc_host *mmc)
 
 	mmc->supply.vmmc = devm_regulator_get_optional(dev, "vmmc");
 	mmc->supply.vqmmc = devm_regulator_get_optional(dev, "vqmmc");
+	mmc->supply.vqmmc2 = devm_regulator_get_optional(dev, "vqmmc2");
 
 	if (IS_ERR(mmc->supply.vmmc)) {
 		if (PTR_ERR(mmc->supply.vmmc) == -EPROBE_DEFER)
@@ -268,6 +296,12 @@ int mmc_regulator_get_supply(struct mmc_host *mmc)
 		dev_dbg(dev, "No vqmmc regulator found\n");
 	}
 
+	if (IS_ERR(mmc->supply.vqmmc2)) {
+		if (PTR_ERR(mmc->supply.vqmmc2) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		dev_dbg(dev, "No vqmmc2 regulator found\n");
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(mmc_regulator_get_supply);
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 0a777caaf7f3..ac9f45e3e203 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -65,6 +65,9 @@ struct mmc_ios {
 #define MMC_TIMING_SD_EXP_1_2V	12
 #define MMC_TIMING_SD_UHS2	13
 
+	unsigned char	vqmmc2_voltage;
+#define MMC_VQMMC2_VOLTAGE_180	0
+
 	unsigned char	signal_voltage;		/* signalling voltage (1.8V or 3.3V) */
 
 #define MMC_SIGNAL_VOLTAGE_330	0
@@ -299,6 +302,7 @@ struct mmc_pwrseq;
 struct mmc_supply {
 	struct regulator *vmmc;		/* Card power supply */
 	struct regulator *vqmmc;	/* Optional Vccq supply */
+	struct regulator *vqmmc2;	/* Optional supply for phy */
 };
 
 struct mmc_ctx {
@@ -579,6 +583,7 @@ int mmc_regulator_set_ocr(struct mmc_host *mmc,
 			struct regulator *supply,
 			unsigned short vdd_bit);
 int mmc_regulator_set_vqmmc(struct mmc_host *mmc, struct mmc_ios *ios);
+int mmc_regulator_set_vqmmc2(struct mmc_host *mmc, struct mmc_ios *ios);
 #else
 static inline int mmc_regulator_set_ocr(struct mmc_host *mmc,
 				 struct regulator *supply,
@@ -592,6 +597,12 @@ static inline int mmc_regulator_set_vqmmc(struct mmc_host *mmc,
 {
 	return -EINVAL;
 }
+
+static inline int mmc_regulator_set_vqmmc2(struct mmc_host *mmc,
+					   struct mmc_ios *ios)
+{
+	return -EINVAL;
+}
 #endif
 
 int mmc_regulator_get_supply(struct mmc_host *mmc);
-- 
2.25.1