// SPDX-License-Identifier: GPL-2.0-only
/*
 * Force-disables a regulator to power down a device
 *
 * Michael Klein <michael@fossekall.de>
 *
 * Copyright (C) 2020 Michael Klein
 *
 * Based on the gpio-poweroff driver.
 */
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/reboot.h>
#include <linux/regulator/consumer.h>

#define TIMEOUT_MS 3000

static int regulator_poweroff_do_poweroff(struct sys_off_data *data)
{
        struct regulator *cpu_regulator = data->cb_data;

        if (cpu_regulator && regulator_is_enabled(cpu_regulator))
                regulator_force_disable(cpu_regulator);

        /* give it some time */
        mdelay(TIMEOUT_MS);

        WARN_ON(1);

        return NOTIFY_DONE;
}

static int regulator_poweroff_probe(struct platform_device *pdev)
{
        struct regulator *cpu_regulator;

        cpu_regulator = devm_regulator_get(&pdev->dev, "cpu");
        if (IS_ERR(cpu_regulator))
                return PTR_ERR(cpu_regulator);

        /* Set this handler to low priority to not override an existing handler */
        return devm_register_sys_off_handler(&pdev->dev,
                                             SYS_OFF_MODE_POWER_OFF,
                                             SYS_OFF_PRIO_LOW,
                                             regulator_poweroff_do_poweroff,
                                             cpu_regulator);
}

static const struct of_device_id of_regulator_poweroff_match[] = {
        { .compatible = "regulator-poweroff", },
        {},
};
MODULE_DEVICE_TABLE(of, of_regulator_poweroff_match);

static struct platform_driver regulator_poweroff_driver = {
        .probe = regulator_poweroff_probe,
        .driver = {
                .name = "poweroff-regulator",
                .of_match_table = of_regulator_poweroff_match,
        },
};

module_platform_driver(regulator_poweroff_driver);

MODULE_AUTHOR("Michael Klein <michael@fossekall.de>");
MODULE_DESCRIPTION("Regulator poweroff driver");
MODULE_ALIAS("platform:poweroff-regulator");