// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * 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 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/module.h>
#include <linux/platform_device.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>
#include <linux/regulator/of_regulator.h>
#include <linux/regulator/gpio-regulator.h>
#include <linux/gpio/consumer.h>
#include <linux/slab.h>
#include <linux/of.h>

struct gpio_regulator_data {
        struct regulator_desc desc;

        struct gpio_desc **gpiods;
        int nr_gpios;

        struct gpio_regulator_state *states;
        int nr_states;

        int state;
};

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_voltage(struct regulator_dev *dev,
                                        int min_uV, int max_uV,
                                        unsigned *selector)
{
        struct gpio_regulator_data *data = rdev_get_drvdata(dev);
        int ptr, target = 0, state, best_val = INT_MAX;

        for (ptr = 0; ptr < data->nr_states; ptr++)
                if (data->states[ptr].value < best_val &&
                    data->states[ptr].value >= min_uV &&
                    data->states[ptr].value <= max_uV) {
                        target = data->states[ptr].gpios;
                        best_val = data->states[ptr].value;
                        if (selector)
                                *selector = ptr;
                }

        if (best_val == INT_MAX)
                return -EINVAL;

        for (ptr = 0; ptr < data->nr_gpios; ptr++) {
                state = (target & (1 << ptr)) >> ptr;
                gpiod_set_value_cansleep(data->gpiods[ptr], state);
        }
        data->state = target;

        return 0;
}

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)
{
        struct gpio_regulator_data *data = rdev_get_drvdata(dev);
        int ptr, target = 0, state, best_val = 0;

        for (ptr = 0; ptr < data->nr_states; ptr++)
                if (data->states[ptr].value > best_val &&
                    data->states[ptr].value >= min_uA &&
                    data->states[ptr].value <= max_uA) {
                        target = data->states[ptr].gpios;
                        best_val = data->states[ptr].value;
                }

        if (best_val == 0)
                return -EINVAL;

        for (ptr = 0; ptr < data->nr_gpios; ptr++) {
                state = (target & (1 << ptr)) >> ptr;
                gpiod_set_value_cansleep(data->gpiods[ptr], state);
        }
        data->state = target;

        return 0;
}

static const struct regulator_ops gpio_regulator_voltage_ops = {
        .get_voltage = gpio_regulator_get_value,
        .set_voltage = gpio_regulator_set_voltage,
        .list_voltage = gpio_regulator_list_voltage,
};

static struct gpio_regulator_config *
of_get_gpio_regulator_config(struct device *dev, struct device_node *np,
                             const struct regulator_desc *desc)
{
        struct gpio_regulator_config *config;
        const char *regtype;
        int proplen, i;
        int ngpios;
        int ret;

        config = devm_kzalloc(dev,
                        sizeof(struct gpio_regulator_config),
                        GFP_KERNEL);
        if (!config)
                return ERR_PTR(-ENOMEM);

        config->init_data = of_get_regulator_init_data(dev, np, desc);
        if (!config->init_data)
                return ERR_PTR(-EINVAL);

        config->supply_name = config->init_data->constraints.name;

        if (config->init_data->constraints.boot_on)
                config->enabled_at_boot = true;

        /*
         * Do not use: undocumented device tree property.
         * This is kept around solely for device tree ABI stability.
         */
        if (of_property_read_bool(np, "enable-at-boot"))
                config->enabled_at_boot = true;

        of_property_read_u32(np, "startup-delay-us", &config->startup_delay);

        /* Fetch GPIO init levels */
        ngpios = gpiod_count(dev, NULL);
        if (ngpios > 0) {
                config->gflags = devm_kzalloc(dev,
                                              sizeof(enum gpiod_flags)
                                              * ngpios,
                                              GFP_KERNEL);
                if (!config->gflags)
                        return ERR_PTR(-ENOMEM);

                for (i = 0; i < ngpios; i++) {
                        u32 val;

                        ret = of_property_read_u32_index(np, "gpios-states", i,
                                                         &val);

                        /* Default to high per specification */
                        if (ret)
                                config->gflags[i] = GPIOD_OUT_HIGH;
                        else
                                config->gflags[i] =
                                        val ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
                }
        }
        config->ngpios = ngpios;

        /* Fetch states. */
        proplen = of_property_count_u32_elems(np, "states");
        if (proplen < 0) {
                dev_err(dev, "No 'states' property found\n");
                return ERR_PTR(-EINVAL);
        }

        config->states = devm_kcalloc(dev,
                                proplen / 2,
                                sizeof(struct gpio_regulator_state),
                                GFP_KERNEL);
        if (!config->states)
                return ERR_PTR(-ENOMEM);

        for (i = 0; i < proplen / 2; i++) {
                of_property_read_u32_index(np, "states", i * 2,
                                           &config->states[i].value);
                of_property_read_u32_index(np, "states", i * 2 + 1,
                                           &config->states[i].gpios);
        }
        config->nr_states = i;

        config->type = REGULATOR_VOLTAGE;
        ret = of_property_read_string(np, "regulator-type", &regtype);
        if (ret >= 0) {
                if (!strncmp("voltage", regtype, 7))
                        config->type = REGULATOR_VOLTAGE;
                else if (!strncmp("current", regtype, 7))
                        config->type = REGULATOR_CURRENT;
                else
                        dev_warn(dev, "Unknown regulator-type '%s'\n",
                                 regtype);
        }

        if (of_property_present(np, "vin-supply"))
                config->input_supply = "vin";

        return config;
}

static const struct regulator_ops gpio_regulator_current_ops = {
        .get_current_limit = gpio_regulator_get_value,
        .set_current_limit = gpio_regulator_set_current_limit,
};

static int gpio_regulator_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct gpio_regulator_config *config = dev_get_platdata(dev);
        struct device_node *np = dev->of_node;
        struct gpio_regulator_data *drvdata;
        struct regulator_config cfg = { };
        struct regulator_dev *rdev;
        enum gpiod_flags gflags;
        int ptr, state, i;

        drvdata = devm_kzalloc(dev, sizeof(struct gpio_regulator_data),
                               GFP_KERNEL);
        if (drvdata == NULL)
                return -ENOMEM;

        if (np) {
                config = of_get_gpio_regulator_config(dev, np,
                                                      &drvdata->desc);
                if (IS_ERR(config))
                        return PTR_ERR(config);
        }

        drvdata->desc.name = devm_kstrdup(dev, config->supply_name, GFP_KERNEL);
        if (drvdata->desc.name == NULL) {
                dev_err(dev, "Failed to allocate supply name\n");
                return -ENOMEM;
        }

        drvdata->gpiods = devm_kcalloc(dev, config->ngpios,
                                       sizeof(struct gpio_desc *), GFP_KERNEL);
        if (!drvdata->gpiods)
                return -ENOMEM;

        if (config->input_supply) {
                drvdata->desc.supply_name = devm_kstrdup(&pdev->dev,
                                                         config->input_supply,
                                                         GFP_KERNEL);
                if (!drvdata->desc.supply_name) {
                        dev_err(&pdev->dev,
                                "Failed to allocate input supply\n");
                        return -ENOMEM;
                }
        }

        for (i = 0; i < config->ngpios; i++) {
                drvdata->gpiods[i] = devm_gpiod_get_index(dev,
                                                          NULL,
                                                          i,
                                                          config->gflags[i]);
                if (IS_ERR(drvdata->gpiods[i]))
                        return PTR_ERR(drvdata->gpiods[i]);
                /* This is good to know */
                gpiod_set_consumer_name(drvdata->gpiods[i], drvdata->desc.name);
        }
        drvdata->nr_gpios = config->ngpios;

        drvdata->states = devm_kmemdup(dev,
                                       config->states,
                                       config->nr_states *
                                       sizeof(struct gpio_regulator_state),
                                       GFP_KERNEL);
        if (drvdata->states == NULL) {
                dev_err(dev, "Failed to allocate state data\n");
                return -ENOMEM;
        }
        drvdata->nr_states = config->nr_states;

        drvdata->desc.owner = THIS_MODULE;
        drvdata->desc.enable_time = config->startup_delay;

        /* 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(dev, "No regulator type set\n");
                return -EINVAL;
        }

        /* build initial state from gpio init data. */
        state = 0;
        for (ptr = 0; ptr < drvdata->nr_gpios; ptr++) {
                if (config->gflags[ptr] == GPIOD_OUT_HIGH)
                        state |= (1 << ptr);
        }
        drvdata->state = state;

        cfg.dev = dev;
        cfg.init_data = config->init_data;
        cfg.driver_data = drvdata;
        cfg.of_node = np;

        /*
         * The signal will be inverted by the GPIO core if flagged so in the
         * descriptor.
         */
        if (config->enabled_at_boot)
                gflags = GPIOD_OUT_HIGH | GPIOD_FLAGS_BIT_NONEXCLUSIVE;
        else
                gflags = GPIOD_OUT_LOW | GPIOD_FLAGS_BIT_NONEXCLUSIVE;

        cfg.ena_gpiod = gpiod_get_optional(dev, "enable", gflags);
        if (IS_ERR(cfg.ena_gpiod))
                return PTR_ERR(cfg.ena_gpiod);

        rdev = devm_regulator_register(dev, &drvdata->desc, &cfg);
        if (IS_ERR(rdev))
                return dev_err_probe(dev, PTR_ERR(rdev),
                                     "Failed to register regulator\n");

        platform_set_drvdata(pdev, drvdata);

        return 0;
}

#if defined(CONFIG_OF)
static const struct of_device_id regulator_gpio_of_match[] = {
        { .compatible = "regulator-gpio", },
        {},
};
MODULE_DEVICE_TABLE(of, regulator_gpio_of_match);
#endif

static struct platform_driver gpio_regulator_driver = {
        .probe          = gpio_regulator_probe,
        .driver         = {
                .name           = "gpio-regulator",
                .probe_type     = PROBE_PREFER_ASYNCHRONOUS,
                .of_match_table = of_match_ptr(regulator_gpio_of_match),
        },
};

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");