regulator: pwm: Support for enable GPIO

Add an optional enable GPIO to the pwm-regulator driver.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/pwm-regulator.txt

@@ -38,13 +38,18 @@ NB: To be clear, if voltage-table is provided, then the device will be used
 in Voltage Table Mode.  If no voltage-table is provided, then the device will
 be used in Continuous Voltage Mode.
 
+Optional properties:
+--------------------
+- enable-gpios:		GPIO to use to enable/disable the regulator
+
 Any property defined as part of the core regulator binding can also be used.
 (See: ../regulator/regulator.txt)
 
-Continuous Voltage Example:
+Continuous Voltage With Enable GPIO Example:
 	pwm_regulator {
 		compatible = "pwm-regulator;
 		pwms = <&pwm1 0 8448 0>;
+		enable-gpios = <&gpio0 23 GPIO_ACTIVE_HIGH>;
 		regulator-min-microvolt = <1016000>;
 		regulator-max-microvolt = <1114000>;
 		regulator-name = "vdd_logic";

drivers/regulator/pwm-regulator.c

@@ -20,6 +20,7 @@
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/pwm.h>
+#include <linux/gpio/consumer.h>
 
 struct pwm_regulator_data {
 	/*  Shared */
@@ -38,6 +39,9 @@ struct pwm_regulator_data {
 
 	/* Continuous voltage */
 	int volt_uV;
+
+	/* Enable GPIO */
+	struct gpio_desc *enb_gpio;
 };
 
 struct pwm_voltages {
@@ -94,6 +98,9 @@ static int pwm_regulator_enable(struct regulator_dev *dev)
 {
 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
 
+	if (drvdata->enb_gpio)
+		gpiod_set_value_cansleep(drvdata->enb_gpio, 1);
+
 	return pwm_enable(drvdata->pwm);
 }
 
@@ -103,6 +110,9 @@ static int pwm_regulator_disable(struct regulator_dev *dev)
 
 	pwm_disable(drvdata->pwm);
 
+	if (drvdata->enb_gpio)
+		gpiod_set_value_cansleep(drvdata->enb_gpio, 0);
+
 	return 0;
 }
 
@@ -110,6 +120,9 @@ static int pwm_regulator_is_enabled(struct regulator_dev *dev)
 {
 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
 
+	if (drvdata->enb_gpio && !gpiod_get_value_cansleep(drvdata->enb_gpio))
+		return false;
+
 	return pwm_is_enabled(drvdata->pwm);
 }
 
@@ -248,6 +261,7 @@ static int pwm_regulator_probe(struct platform_device *pdev)
 	struct regulator_dev *regulator;
 	struct regulator_config config = { };
 	struct device_node *np = pdev->dev.of_node;
+	enum gpiod_flags gpio_flags;
 	int ret;
 
 	if (!np) {
@@ -285,6 +299,18 @@ static int pwm_regulator_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	if (init_data->constraints.boot_on || init_data->constraints.always_on)
+		gpio_flags = GPIOD_OUT_HIGH;
+	else
+		gpio_flags = GPIOD_OUT_LOW;
+	drvdata->enb_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
+						    gpio_flags);
+	if (IS_ERR(drvdata->enb_gpio)) {
+		ret = PTR_ERR(drvdata->enb_gpio);
+		dev_err(&pdev->dev, "Failed to get enable GPIO: %d\n", ret);
+		return ret;
+	}
+
 	/*
 	 * FIXME: pwm_apply_args() should be removed when switching to the
 	 * atomic PWM API.