// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * reg-virtual-consumer.c
 *
 * Copyright 2008 Wolfson Microelectronics PLC.
 *
 * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
 */

#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/of.h>

struct virtual_consumer_data {
        struct mutex lock;
        struct regulator *regulator;
        bool enabled;
        int min_uV;
        int max_uV;
        int min_uA;
        int max_uA;
        unsigned int mode;
};

static void update_voltage_constraints(struct device *dev,
                                       struct virtual_consumer_data *data)
{
        int ret;

        if (data->min_uV && data->max_uV
            && data->min_uV <= data->max_uV) {
                dev_dbg(dev, "Requesting %d-%duV\n",
                        data->min_uV, data->max_uV);
                ret = regulator_set_voltage(data->regulator,
                                        data->min_uV, data->max_uV);
                if (ret != 0) {
                        dev_err(dev,
                                "regulator_set_voltage() failed: %d\n", ret);
                        return;
                }
        }

        if (data->min_uV && data->max_uV && !data->enabled) {
                dev_dbg(dev, "Enabling regulator\n");
                ret = regulator_enable(data->regulator);
                if (ret == 0)
                        data->enabled = true;
                else
                        dev_err(dev, "regulator_enable() failed: %d\n",
                                ret);
        }

        if (!(data->min_uV && data->max_uV) && data->enabled) {
                dev_dbg(dev, "Disabling regulator\n");
                ret = regulator_disable(data->regulator);
                if (ret == 0)
                        data->enabled = false;
                else
                        dev_err(dev, "regulator_disable() failed: %d\n",
                                ret);
        }
}

static void update_current_limit_constraints(struct device *dev,
                                          struct virtual_consumer_data *data)
{
        int ret;

        if (data->max_uA
            && data->min_uA <= data->max_uA) {
                dev_dbg(dev, "Requesting %d-%duA\n",
                        data->min_uA, data->max_uA);
                ret = regulator_set_current_limit(data->regulator,
                                        data->min_uA, data->max_uA);
                if (ret != 0) {
                        dev_err(dev,
                                "regulator_set_current_limit() failed: %d\n",
                                ret);
                        return;
                }
        }

        if (data->max_uA && !data->enabled) {
                dev_dbg(dev, "Enabling regulator\n");
                ret = regulator_enable(data->regulator);
                if (ret == 0)
                        data->enabled = true;
                else
                        dev_err(dev, "regulator_enable() failed: %d\n",
                                ret);
        }

        if (!(data->min_uA && data->max_uA) && data->enabled) {
                dev_dbg(dev, "Disabling regulator\n");
                ret = regulator_disable(data->regulator);
                if (ret == 0)
                        data->enabled = false;
                else
                        dev_err(dev, "regulator_disable() failed: %d\n",
                                ret);
        }
}

static ssize_t show_min_uV(struct device *dev,
                           struct device_attribute *attr, char *buf)
{
        struct virtual_consumer_data *data = dev_get_drvdata(dev);
        return sprintf(buf, "%d\n", data->min_uV);
}

static ssize_t set_min_uV(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count)
{
        struct virtual_consumer_data *data = dev_get_drvdata(dev);
        long val;

        if (kstrtol(buf, 10, &val) != 0)
                return count;

        mutex_lock(&data->lock);

        data->min_uV = val;
        update_voltage_constraints(dev, data);

        mutex_unlock(&data->lock);

        return count;
}

static ssize_t show_max_uV(struct device *dev,
                           struct device_attribute *attr, char *buf)
{
        struct virtual_consumer_data *data = dev_get_drvdata(dev);
        return sprintf(buf, "%d\n", data->max_uV);
}

static ssize_t set_max_uV(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count)
{
        struct virtual_consumer_data *data = dev_get_drvdata(dev);
        long val;

        if (kstrtol(buf, 10, &val) != 0)
                return count;

        mutex_lock(&data->lock);

        data->max_uV = val;
        update_voltage_constraints(dev, data);

        mutex_unlock(&data->lock);

        return count;
}

static ssize_t show_min_uA(struct device *dev,
                           struct device_attribute *attr, char *buf)
{
        struct virtual_consumer_data *data = dev_get_drvdata(dev);
        return sprintf(buf, "%d\n", data->min_uA);
}

static ssize_t set_min_uA(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count)
{
        struct virtual_consumer_data *data = dev_get_drvdata(dev);
        long val;

        if (kstrtol(buf, 10, &val) != 0)
                return count;

        mutex_lock(&data->lock);

        data->min_uA = val;
        update_current_limit_constraints(dev, data);

        mutex_unlock(&data->lock);

        return count;
}

static ssize_t show_max_uA(struct device *dev,
                           struct device_attribute *attr, char *buf)
{
        struct virtual_consumer_data *data = dev_get_drvdata(dev);
        return sprintf(buf, "%d\n", data->max_uA);
}

static ssize_t set_max_uA(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count)
{
        struct virtual_consumer_data *data = dev_get_drvdata(dev);
        long val;

        if (kstrtol(buf, 10, &val) != 0)
                return count;

        mutex_lock(&data->lock);

        data->max_uA = val;
        update_current_limit_constraints(dev, data);

        mutex_unlock(&data->lock);

        return count;
}

static ssize_t show_mode(struct device *dev,
                         struct device_attribute *attr, char *buf)
{
        struct virtual_consumer_data *data = dev_get_drvdata(dev);

        switch (data->mode) {
        case REGULATOR_MODE_FAST:
                return sprintf(buf, "fast\n");
        case REGULATOR_MODE_NORMAL:
                return sprintf(buf, "normal\n");
        case REGULATOR_MODE_IDLE:
                return sprintf(buf, "idle\n");
        case REGULATOR_MODE_STANDBY:
                return sprintf(buf, "standby\n");
        default:
                return sprintf(buf, "unknown\n");
        }
}

static ssize_t set_mode(struct device *dev, struct device_attribute *attr,
                        const char *buf, size_t count)
{
        struct virtual_consumer_data *data = dev_get_drvdata(dev);
        unsigned int mode;
        int ret;

        /*
         * sysfs_streq() doesn't need the \n's, but we add them so the strings
         * will be shared with show_mode(), above.
         */
        if (sysfs_streq(buf, "fast\n"))
                mode = REGULATOR_MODE_FAST;
        else if (sysfs_streq(buf, "normal\n"))
                mode = REGULATOR_MODE_NORMAL;
        else if (sysfs_streq(buf, "idle\n"))
                mode = REGULATOR_MODE_IDLE;
        else if (sysfs_streq(buf, "standby\n"))
                mode = REGULATOR_MODE_STANDBY;
        else {
                dev_err(dev, "Configuring invalid mode\n");
                return count;
        }

        mutex_lock(&data->lock);
        ret = regulator_set_mode(data->regulator, mode);
        if (ret == 0)
                data->mode = mode;
        else
                dev_err(dev, "Failed to configure mode: %d\n", ret);
        mutex_unlock(&data->lock);

        return count;
}

static DEVICE_ATTR(min_microvolts, 0664, show_min_uV, set_min_uV);
static DEVICE_ATTR(max_microvolts, 0664, show_max_uV, set_max_uV);
static DEVICE_ATTR(min_microamps, 0664, show_min_uA, set_min_uA);
static DEVICE_ATTR(max_microamps, 0664, show_max_uA, set_max_uA);
static DEVICE_ATTR(mode, 0664, show_mode, set_mode);

static struct attribute *regulator_virtual_attributes[] = {
        &dev_attr_min_microvolts.attr,
        &dev_attr_max_microvolts.attr,
        &dev_attr_min_microamps.attr,
        &dev_attr_max_microamps.attr,
        &dev_attr_mode.attr,
        NULL
};

static const struct attribute_group regulator_virtual_attr_group = {
        .attrs  = regulator_virtual_attributes,
};

#ifdef CONFIG_OF
static const struct of_device_id regulator_virtual_consumer_of_match[] = {
        { .compatible = "regulator-virtual-consumer" },
        {},
};
MODULE_DEVICE_TABLE(of, regulator_virtual_consumer_of_match);
#endif

static int regulator_virtual_probe(struct platform_device *pdev)
{
        char *reg_id = dev_get_platdata(&pdev->dev);
        struct virtual_consumer_data *drvdata;
        static bool warned;
        int ret;

        if (!warned) {
                warned = true;
                pr_warn("**********************************************************\n");
                pr_warn("**   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **\n");
                pr_warn("**                                                      **\n");
                pr_warn("** regulator-virtual-consumer is only for testing and   **\n");
                pr_warn("** debugging.  Do not use it in a production kernel.    **\n");
                pr_warn("**                                                      **\n");
                pr_warn("**   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **\n");
                pr_warn("**********************************************************\n");
        }

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

        /*
         * This virtual consumer does not have any hardware-defined supply
         * name, so just allow the regulator to be specified in a property
         * named "default-supply" when we're being probed from devicetree.
         */
        if (!reg_id && pdev->dev.of_node)
                reg_id = "default";

        mutex_init(&drvdata->lock);

        drvdata->regulator = devm_regulator_get(&pdev->dev, reg_id);
        if (IS_ERR(drvdata->regulator))
                return dev_err_probe(&pdev->dev, PTR_ERR(drvdata->regulator),
                                     "Failed to obtain supply '%s'\n",
                                     reg_id);

        ret = sysfs_create_group(&pdev->dev.kobj,
                                 &regulator_virtual_attr_group);
        if (ret != 0) {
                dev_err(&pdev->dev,
                        "Failed to create attribute group: %d\n", ret);
                return ret;
        }

        drvdata->mode = regulator_get_mode(drvdata->regulator);

        platform_set_drvdata(pdev, drvdata);

        return 0;
}

static void regulator_virtual_remove(struct platform_device *pdev)
{
        struct virtual_consumer_data *drvdata = platform_get_drvdata(pdev);

        sysfs_remove_group(&pdev->dev.kobj, &regulator_virtual_attr_group);

        if (drvdata->enabled)
                regulator_disable(drvdata->regulator);
}

static struct platform_driver regulator_virtual_consumer_driver = {
        .probe          = regulator_virtual_probe,
        .remove         = regulator_virtual_remove,
        .driver         = {
                .name           = "reg-virt-consumer",
                .probe_type     = PROBE_PREFER_ASYNCHRONOUS,
                .of_match_table = of_match_ptr(regulator_virtual_consumer_of_match),
        },
};

module_platform_driver(regulator_virtual_consumer_driver);

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