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

struct fixed_voltage_data {
        struct regulator_desc desc;
        struct regulator_dev *dev;
};


/**
 * of_get_fixed_voltage_config - extract fixed_voltage_config structure info
 * @dev: device requesting for fixed_voltage_config
 * @desc: regulator description
 *
 * Populates fixed_voltage_config structure by extracting data from device
 * tree node, returns a pointer to the populated structure of NULL if memory
 * alloc fails.
 */
static struct fixed_voltage_config *
of_get_fixed_voltage_config(struct device *dev,
                            const struct regulator_desc *desc)
{
        struct fixed_voltage_config *config;
        struct device_node *np = dev->of_node;
        struct regulator_init_data *init_data;

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

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

        init_data = config->init_data;
        init_data->constraints.apply_uV = 0;

        config->supply_name = init_data->constraints.name;
        if (init_data->constraints.min_uV == init_data->constraints.max_uV) {
                config->microvolts = init_data->constraints.min_uV;
        } else {
                dev_err(dev,
                         "Fixed regulator specified with variable voltages\n");
                return ERR_PTR(-EINVAL);
        }

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

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

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

        return config;
}

static struct regulator_ops fixed_voltage_ops = {
};

static int reg_fixed_voltage_probe(struct platform_device *pdev)
{
        struct fixed_voltage_config *config;
        struct fixed_voltage_data *drvdata;
        struct regulator_config cfg = { };
        enum gpiod_flags gflags;
        int ret;

        drvdata = devm_kzalloc(&pdev->dev, sizeof(struct fixed_voltage_data),
                               GFP_KERNEL);
        if (!drvdata)
                return -ENOMEM;

        if (pdev->dev.of_node) {
                config = of_get_fixed_voltage_config(&pdev->dev,
                                                     &drvdata->desc);
                if (IS_ERR(config))
                        return PTR_ERR(config);
        } else {
                config = dev_get_platdata(&pdev->dev);
        }

        if (!config)
                return -ENOMEM;

        drvdata->desc.name = devm_kstrdup(&pdev->dev,
                                          config->supply_name,
                                          GFP_KERNEL);
        if (drvdata->desc.name == NULL) {
                dev_err(&pdev->dev, "Failed to allocate supply name\n");
                return -ENOMEM;
        }
        drvdata->desc.type = REGULATOR_VOLTAGE;
        drvdata->desc.owner = THIS_MODULE;
        drvdata->desc.ops = &fixed_voltage_ops;

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

        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;
                }
        }

        if (config->microvolts)
                drvdata->desc.n_voltages = 1;

        drvdata->desc.fixed_uV = config->microvolts;

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

        /*
         * Some fixed regulators share the enable line between two
         * regulators which makes it necessary to get a handle on the
         * same descriptor for two different consumers. This will get
         * the GPIO descriptor, but only the first call will initialize
         * it so any flags such as inversion or open drain will only
         * be set up by the first caller and assumed identical on the
         * next caller.
         *
         * FIXME: find a better way to deal with this.
         */
        gflags |= GPIOD_FLAGS_BIT_NONEXCLUSIVE;

        /*
         * Do not use devm* here: the regulator core takes over the
         * lifecycle management of the GPIO descriptor.
         */
        cfg.ena_gpiod = gpiod_get_optional(&pdev->dev, NULL, gflags);
        if (IS_ERR(cfg.ena_gpiod))
                return PTR_ERR(cfg.ena_gpiod);

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

        drvdata->dev = devm_regulator_register(&pdev->dev, &drvdata->desc,
                                               &cfg);
        if (IS_ERR(drvdata->dev)) {
                ret = PTR_ERR(drvdata->dev);
                dev_err(&pdev->dev, "Failed to register regulator: %d\n", ret);
                return ret;
        }

        platform_set_drvdata(pdev, drvdata);

        dev_dbg(&pdev->dev, "%s supplying %duV\n", drvdata->desc.name,
                drvdata->desc.fixed_uV);

        return 0;
}

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

static struct platform_driver regulator_fixed_voltage_driver = {
        .probe          = reg_fixed_voltage_probe,
        .driver         = {
                .name           = "reg-fixed-voltage",
                .of_match_table = of_match_ptr(fixed_of_match),
        },
};

static int __init regulator_fixed_voltage_init(void)
{
        return platform_driver_register(&regulator_fixed_voltage_driver);
}
subsys_initcall(regulator_fixed_voltage_init);

static void __exit regulator_fixed_voltage_exit(void)
{
        platform_driver_unregister(&regulator_fixed_voltage_driver);
}
module_exit(regulator_fixed_voltage_exit);

MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
MODULE_DESCRIPTION("Fixed voltage regulator");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:reg-fixed-voltage");