regulator: Add driver for gpio-controlled regulators

This patch adds support for regulators that can be controlled via gpios.

Examples for such regulators are the TI-tps65024x voltage regulators
with 4 fixed and 1 runtime-switchable voltage regulators
or the TI-bq240XX charger regulators.

The number of controlling gpios is not limited, the mapping between
voltage/current and target gpio state is done via the states map
and the driver can be used for either voltage or current regulators.

A mapping for a regulator with two GPIOs could look like:

gpios = {
	{ .gpio = GPIO1, .flags = GPIOF_OUT_INIT_HIGH, .label = "gpio name 1" },
	{ .gpio = GPIO2, .flags = GPIOF_OUT_INIT_LOW,  .label = "gpio name 2" },
}

The flags element of the gpios array determines the initial state of
the gpio, set during probe. The initial state of the regulator is also
calculated from these values

states = {
	{ .value = volt_or_cur1, .gpios = (0 << 1) | (0 << 0) },
	{ .value = volt_or_cur2, .gpios = (0 << 1) | (1 << 0) },
	{ .value = volt_or_cur3, .gpios = (1 << 1) | (0 << 0) },
	{ .value = volt_or_cur4, .gpios = (1 << 1) | (1 << 0) },
}

The target-state for the n-th gpio is determined by the n-th bit
in the bitfield of the target-value.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

3 files changed, 367 insertions, 0 deletions

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index c7fd2c0e3f2b..5e0c7b664732 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -64,6 +64,15 @@ config REGULATOR_USERSPACE_CONSUMER
 
           If unsure, say no.
 
+config REGULATOR_GPIO
+        tristate "GPIO regulator support"
+        help
+          This driver provides support for regulators that can be
+          controlled via gpios.
+          It is capable of supporting current and voltage regulators
+          and the platform has to provide a mapping of GPIO-states
+          to target volts/amps.
+
 config REGULATOR_BQ24022
         tristate "TI bq24022 Dual Input 1-Cell Li-Ion Charger IC"
         help
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index 040d5aa63535..93a6318f5328 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_REGULATOR_FIXED_VOLTAGE) += fixed.o
 obj-$(CONFIG_REGULATOR_VIRTUAL_CONSUMER) += virtual.o
 obj-$(CONFIG_REGULATOR_USERSPACE_CONSUMER) += userspace-consumer.o
 
+obj-$(CONFIG_REGULATOR_GPIO) += gpio-regulator.o
 obj-$(CONFIG_REGULATOR_AD5398) += ad5398.o
 obj-$(CONFIG_REGULATOR_BQ24022) += bq24022.o
 obj-$(CONFIG_REGULATOR_LP3971) += lp3971.o
diff --git a/drivers/regulator/gpio-regulator.c b/drivers/regulator/gpio-regulator.c
new file mode 100644
index 000000000000..abf32ad6f573
--- /dev/null
+++ b/drivers/regulator/gpio-regulator.c
@@ -0,0 +1,357 @@
+/*
+ * gpio-regulator.c
+ *
+ * Copyright 2011 Heiko Stuebner <heiko@sntech.de>
+ *
+ * based on fixed.c
+ *
+ * Copyright 2008 Wolfson Microelectronics PLC.
+ *
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ *
+ * Copyright (c) 2009 Nokia Corporation
+ * Roger Quadros <ext-roger.quadros@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This is useful for systems with mixed controllable and
+ * non-controllable regulators, as well as for allowing testing on
+ * systems with no controllable regulators.
+ */
+
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/gpio-regulator.h>
+#include <linux/gpio.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+
+struct gpio_regulator_data {
+        struct regulator_desc desc;
+        struct regulator_dev *dev;
+
+        int enable_gpio;
+        bool enable_high;
+        bool is_enabled;
+        unsigned startup_delay;
+
+        struct gpio *gpios;
+        int nr_gpios;
+
+        struct gpio_regulator_state *states;
+        int nr_states;
+
+        int state;
+};
+
+static int gpio_regulator_is_enabled(struct regulator_dev *dev)
+{
+        struct gpio_regulator_data *data = rdev_get_drvdata(dev);
+
+        return data->is_enabled;
+}
+
+static int gpio_regulator_enable(struct regulator_dev *dev)
+{
+        struct gpio_regulator_data *data = rdev_get_drvdata(dev);
+
+        if (gpio_is_valid(data->enable_gpio)) {
+                gpio_set_value_cansleep(data->enable_gpio, data->enable_high);
+                data->is_enabled = true;
+        }
+
+        return 0;
+}
+
+static int gpio_regulator_disable(struct regulator_dev *dev)
+{
+        struct gpio_regulator_data *data = rdev_get_drvdata(dev);
+
+        if (gpio_is_valid(data->enable_gpio)) {
+                gpio_set_value_cansleep(data->enable_gpio, !data->enable_high);
+                data->is_enabled = false;
+        }
+
+        return 0;
+}
+
+static int gpio_regulator_enable_time(struct regulator_dev *dev)
+{
+        struct gpio_regulator_data *data = rdev_get_drvdata(dev);
+
+        return data->startup_delay;
+}
+
+static int gpio_regulator_get_value(struct regulator_dev *dev)
+{
+        struct gpio_regulator_data *data = rdev_get_drvdata(dev);
+        int ptr;
+
+        for (ptr = 0; ptr < data->nr_states; ptr++)
+                if (data->states[ptr].gpios == data->state)
+                        return data->states[ptr].value;
+
+        return -EINVAL;
+}
+
+static int gpio_regulator_set_value(struct regulator_dev *dev,
+                                        int min, int max)
+{
+        struct gpio_regulator_data *data = rdev_get_drvdata(dev);
+        int ptr, target, state;
+
+        target = -1;
+        for (ptr = 0; ptr < data->nr_states; ptr++)
+                if (data->states[ptr].value >= min &&
+                    data->states[ptr].value <= max)
+                        target = data->states[ptr].gpios;
+
+        if (target < 0)
+                return -EINVAL;
+
+        for (ptr = 0; ptr < data->nr_gpios; ptr++) {
+                state = (target & (1 << ptr)) >> ptr;
+                gpio_set_value(data->gpios[ptr].gpio, state);
+        }
+        data->state = target;
+
+        return 0;
+}
+
+static int gpio_regulator_set_voltage(struct regulator_dev *dev,
+                                        int min_uV, int max_uV,
+                                        unsigned *selector)
+{
+        return gpio_regulator_set_value(dev, min_uV, max_uV);
+}
+
+static int gpio_regulator_list_voltage(struct regulator_dev *dev,
+                                      unsigned selector)
+{
+        struct gpio_regulator_data *data = rdev_get_drvdata(dev);
+
+        if (selector >= data->nr_states)
+                return -EINVAL;
+
+        return data->states[selector].value;
+}
+
+static int gpio_regulator_set_current_limit(struct regulator_dev *dev,
+                                        int min_uA, int max_uA)
+{
+        return gpio_regulator_set_value(dev, min_uA, max_uA);
+}
+
+static struct regulator_ops gpio_regulator_voltage_ops = {
+        .is_enabled = gpio_regulator_is_enabled,
+        .enable = gpio_regulator_enable,
+        .disable = gpio_regulator_disable,
+        .enable_time = gpio_regulator_enable_time,
+        .get_voltage = gpio_regulator_get_value,
+        .set_voltage = gpio_regulator_set_voltage,
+        .list_voltage = gpio_regulator_list_voltage,
+};
+
+static struct regulator_ops gpio_regulator_current_ops = {
+        .is_enabled = gpio_regulator_is_enabled,
+        .enable = gpio_regulator_enable,
+        .disable = gpio_regulator_disable,
+        .enable_time = gpio_regulator_enable_time,
+        .get_current_limit = gpio_regulator_get_value,
+        .set_current_limit = gpio_regulator_set_current_limit,
+};
+
+static int __devinit gpio_regulator_probe(struct platform_device *pdev)
+{
+        struct gpio_regulator_config *config = pdev->dev.platform_data;
+        struct gpio_regulator_data *drvdata;
+        int ptr, ret, state;
+
+        drvdata = kzalloc(sizeof(struct gpio_regulator_data), GFP_KERNEL);
+        if (drvdata == NULL) {
+                dev_err(&pdev->dev, "Failed to allocate device data\n");
+                return -ENOMEM;
+        }
+
+        drvdata->desc.name = kstrdup(config->supply_name, GFP_KERNEL);
+        if (drvdata->desc.name == NULL) {
+                dev_err(&pdev->dev, "Failed to allocate supply name\n");
+                ret = -ENOMEM;
+                goto err;
+        }
+
+        drvdata->gpios = kmemdup(config->gpios,
+                                 config->nr_gpios * sizeof(struct gpio),
+                                 GFP_KERNEL);
+        if (drvdata->gpios == NULL) {
+                dev_err(&pdev->dev, "Failed to allocate gpio data\n");
+                ret = -ENOMEM;
+                goto err_name;
+        }
+
+        drvdata->states = kmemdup(config->states,
+                                  config->nr_states *
+                                         sizeof(struct gpio_regulator_state),
+                                  GFP_KERNEL);
+        if (drvdata->states == NULL) {
+                dev_err(&pdev->dev, "Failed to allocate state data\n");
+                ret = -ENOMEM;
+                goto err_memgpio;
+        }
+        drvdata->nr_states = config->nr_states;
+
+        drvdata->desc.owner = THIS_MODULE;
+
+        /* handle regulator type*/
+        switch (config->type) {
+        case REGULATOR_VOLTAGE:
+                drvdata->desc.type = REGULATOR_VOLTAGE;
+                drvdata->desc.ops = &gpio_regulator_voltage_ops;
+                drvdata->desc.n_voltages = config->nr_states;
+                break;
+        case REGULATOR_CURRENT:
+                drvdata->desc.type = REGULATOR_CURRENT;
+                drvdata->desc.ops = &gpio_regulator_current_ops;
+                break;
+        default:
+                dev_err(&pdev->dev, "No regulator type set\n");
+                ret = -EINVAL;
+                goto err_memgpio;
+                break;
+        }
+
+        drvdata->enable_gpio = config->enable_gpio;
+        drvdata->startup_delay = config->startup_delay;
+
+        if (gpio_is_valid(config->enable_gpio)) {
+                drvdata->enable_high = config->enable_high;
+
+                ret = gpio_request(config->enable_gpio, config->supply_name);
+                if (ret) {
+                        dev_err(&pdev->dev,
+                           "Could not obtain regulator enable GPIO %d: %d\n",
+                                                config->enable_gpio, ret);
+                        goto err_memstate;
+                }
+
+                /* set output direction without changing state
+                 * to prevent glitch
+                 */
+                if (config->enabled_at_boot) {
+                        drvdata->is_enabled = true;
+                        ret = gpio_direction_output(config->enable_gpio,
+                                                    config->enable_high);
+                } else {
+                        drvdata->is_enabled = false;
+                        ret = gpio_direction_output(config->enable_gpio,
+                                                    !config->enable_high);
+                }
+
+                if (ret) {
+                        dev_err(&pdev->dev,
+                           "Could not configure regulator enable GPIO %d direction: %d\n",
+                                                config->enable_gpio, ret);
+                        goto err_enablegpio;
+                }
+        } else {
+                /* Regulator without GPIO control is considered
+                 * always enabled
+                 */
+                drvdata->is_enabled = true;
+        }
+
+        drvdata->nr_gpios = config->nr_gpios;
+        ret = gpio_request_array(drvdata->gpios, drvdata->nr_gpios);
+        if (ret) {
+                dev_err(&pdev->dev,
+                   "Could not obtain regulator setting GPIOs: %d\n", ret);
+                goto err_enablegpio;
+        }
+
+        /* build initial state from gpio init data. */
+        state = 0;
+        for (ptr = 0; ptr < drvdata->nr_gpios; ptr++) {
+                if (config->gpios[ptr].flags & GPIOF_OUT_INIT_HIGH)
+                        state |= (1 << ptr);
+        }
+        drvdata->state = state;
+
+        drvdata->dev = regulator_register(&drvdata->desc, &pdev->dev,
+                                          config->init_data, drvdata);
+        if (IS_ERR(drvdata->dev)) {
+                ret = PTR_ERR(drvdata->dev);
+                dev_err(&pdev->dev, "Failed to register regulator: %d\n", ret);
+                goto err_stategpio;
+        }
+
+        platform_set_drvdata(pdev, drvdata);
+
+        return 0;
+
+err_stategpio:
+        gpio_free_array(drvdata->gpios, drvdata->nr_gpios);
+err_enablegpio:
+        if (gpio_is_valid(config->enable_gpio))
+                gpio_free(config->enable_gpio);
+err_memstate:
+        kfree(drvdata->states);
+err_memgpio:
+        kfree(drvdata->gpios);
+err_name:
+        kfree(drvdata->desc.name);
+err:
+        kfree(drvdata);
+        return ret;
+}
+
+static int __devexit gpio_regulator_remove(struct platform_device *pdev)
+{
+        struct gpio_regulator_data *drvdata = platform_get_drvdata(pdev);
+
+        regulator_unregister(drvdata->dev);
+
+        gpio_free_array(drvdata->gpios, drvdata->nr_gpios);
+
+        kfree(drvdata->states);
+        kfree(drvdata->gpios);
+
+        if (gpio_is_valid(drvdata->enable_gpio))
+                gpio_free(drvdata->enable_gpio);
+
+        kfree(drvdata->desc.name);
+        kfree(drvdata);
+
+        return 0;
+}
+
+static struct platform_driver gpio_regulator_driver = {
+        .probe          = gpio_regulator_probe,
+        .remove         = __devexit_p(gpio_regulator_remove),
+        .driver         = {
+                .name           = "gpio-regulator",
+                .owner          = THIS_MODULE,
+        },
+};
+
+static int __init gpio_regulator_init(void)
+{
+        return platform_driver_register(&gpio_regulator_driver);
+}
+subsys_initcall(gpio_regulator_init);
+
+static void __exit gpio_regulator_exit(void)
+{
+        platform_driver_unregister(&gpio_regulator_driver);
+}
+module_exit(gpio_regulator_exit);
+
+MODULE_AUTHOR("Heiko Stuebner <heiko@sntech.de>");
+MODULE_DESCRIPTION("gpio voltage regulator");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gpio-regulator");