power: regulator: Add support for gpio regulators

Add support for gpio regulators. As of now this driver caters
to gpio regulators with one gpio. Supports setting voltage values to gpio
regulators and retrieving the values.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/power/regulator/Kconfig

@@ -68,6 +68,14 @@ config DM_REGULATOR_FIXED
 	features for fixed value regulators. The driver implements get/set api
 	for enable and get only for voltage value.
 
+config DM_REGULATOR_GPIO
+	bool "Enable Driver Model for GPIO REGULATOR"
+	depends on DM_REGULATOR
+	---help---
+	This config enables implementation of driver-model regulator uclass
+	features for gpio regulators. The driver implements get/set for
+	voltage value.
+
 config REGULATOR_RK808
 	bool "Enable driver for RK808 regulators"
 	depends on DM_REGULATOR && PMIC_RK808

drivers/power/regulator/Makefile

@@ -11,6 +11,7 @@ obj-$(CONFIG_DM_REGULATOR_MAX77686) += max77686.o
 obj-$(CONFIG_DM_REGULATOR_PFUZE100) += pfuze100.o
 obj-$(CONFIG_REGULATOR_PWM) += pwm_regulator.o
 obj-$(CONFIG_$(SPL_)DM_REGULATOR_FIXED) += fixed.o
+obj-$(CONFIG_$(SPL_)DM_REGULATOR_GPIO) += gpio-regulator.o
 obj-$(CONFIG_REGULATOR_RK808) += rk808.o
 obj-$(CONFIG_REGULATOR_S5M8767) += s5m8767.o
 obj-$(CONFIG_DM_REGULATOR_SANDBOX) += sandbox.o

drivers/power/regulator/gpio-regulator.c

@@ -0,0 +1,137 @@
+/*
+ * (C) Copyright 2016 Texas Instruments Incorporated, <www.ti.com>
+ * Keerthy <j-keerthy@ti.com>
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#include <common.h>
+#include <fdtdec.h>
+#include <errno.h>
+#include <dm.h>
+#include <i2c.h>
+#include <asm/gpio.h>
+#include <power/pmic.h>
+#include <power/regulator.h>
+
+#define GPIO_REGULATOR_MAX_STATES	2
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct gpio_regulator_platdata {
+	struct gpio_desc gpio; /* GPIO for regulator voltage control */
+	int states[GPIO_REGULATOR_MAX_STATES];
+	int voltages[GPIO_REGULATOR_MAX_STATES];
+};
+
+static int gpio_regulator_ofdata_to_platdata(struct udevice *dev)
+{
+	struct dm_regulator_uclass_platdata *uc_pdata;
+	struct gpio_regulator_platdata *dev_pdata;
+	struct gpio_desc *gpio;
+	const void *blob = gd->fdt_blob;
+	int node = dev->of_offset;
+	int ret, count, i, j;
+	u32 states_array[8];
+
+	dev_pdata = dev_get_platdata(dev);
+	uc_pdata = dev_get_uclass_platdata(dev);
+	if (!uc_pdata)
+		return -ENXIO;
+
+	/* Set type to gpio */
+	uc_pdata->type = REGULATOR_TYPE_GPIO;
+
+	/*
+	 * Get gpio regulator gpio desc
+	 * Assuming one GPIO per regulator.
+	 * Can be extended later to multiple GPIOs
+	 * per gpio-regulator. As of now no instance with multiple
+	 * gpios is presnt
+	 */
+	gpio = &dev_pdata->gpio;
+	ret = gpio_request_by_name(dev, "gpios", 0, gpio, GPIOD_IS_OUT);
+	if (ret)
+		debug("regulator gpio - not found! Error: %d", ret);
+
+	count = fdtdec_get_int_array_count(blob, node, "states",
+					   states_array, 8);
+
+	if (!count)
+		return -EINVAL;
+
+	for (i = 0, j = 0; i < count; i += 2) {
+		dev_pdata->voltages[j] = states_array[i];
+		dev_pdata->states[j] = states_array[i + 1];
+		j++;
+	}
+
+	return 0;
+}
+
+static int gpio_regulator_get_value(struct udevice *dev)
+{
+	struct dm_regulator_uclass_platdata *uc_pdata;
+	struct gpio_regulator_platdata *dev_pdata = dev_get_platdata(dev);
+	int enable;
+
+	if (!dev_pdata->gpio.dev)
+		return -ENOSYS;
+
+	uc_pdata = dev_get_uclass_platdata(dev);
+	if (uc_pdata->min_uV > uc_pdata->max_uV) {
+		debug("Invalid constraints for: %s\n", uc_pdata->name);
+		return -EINVAL;
+	}
+
+	enable = dm_gpio_get_value(&dev_pdata->gpio);
+	if (enable == dev_pdata->states[0])
+		return dev_pdata->voltages[0];
+	else
+		return dev_pdata->voltages[1];
+}
+
+static int gpio_regulator_set_value(struct udevice *dev, int uV)
+{
+	struct gpio_regulator_platdata *dev_pdata = dev_get_platdata(dev);
+	int ret;
+	bool enable;
+
+	if (!dev_pdata->gpio.dev)
+		return -ENOSYS;
+
+	if (uV == dev_pdata->voltages[0])
+		enable = dev_pdata->states[0];
+	else if (uV == dev_pdata->voltages[1])
+		enable = dev_pdata->states[1];
+	else
+		return -EINVAL;
+
+	ret = dm_gpio_set_value(&dev_pdata->gpio, enable);
+	if (ret) {
+		error("Can't set regulator : %s gpio to: %d\n", dev->name,
+		      enable);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct dm_regulator_ops gpio_regulator_ops = {
+	.get_value	= gpio_regulator_get_value,
+	.set_value	= gpio_regulator_set_value,
+};
+
+static const struct udevice_id gpio_regulator_ids[] = {
+	{ .compatible = "regulator-gpio" },
+	{ },
+};
+
+U_BOOT_DRIVER(gpio_regulator) = {
+	.name = "gpio regulator",
+	.id = UCLASS_REGULATOR,
+	.ops = &gpio_regulator_ops,
+	.of_match = gpio_regulator_ids,
+	.ofdata_to_platdata = gpio_regulator_ofdata_to_platdata,
+	.platdata_auto_alloc_size = sizeof(struct gpio_regulator_platdata),
+};

include/power/regulator.h

@@ -108,6 +108,7 @@ enum regulator_type {
 	REGULATOR_TYPE_BUCK,
 	REGULATOR_TYPE_DVS,
 	REGULATOR_TYPE_FIXED,
+	REGULATOR_TYPE_GPIO,
 	REGULATOR_TYPE_OTHER,
 };