// SPDX-License-Identifier: GPL-2.0-only
/*
 * Toggles a GPIO pin to power down a device
 *
 * Jamie Lentin <jm@lentin.co.uk>
 * Andrew Lunn <andrew@lunn.ch>
 *
 * Copyright (C) 2012 Jamie Lentin
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/reboot.h>

#define DEFAULT_TIMEOUT_MS 3000

struct gpio_poweroff {
        struct gpio_desc *reset_gpio;
        u32 timeout_ms;
        u32 active_delay_ms;
        u32 inactive_delay_ms;
};

static int gpio_poweroff_do_poweroff(struct sys_off_data *data)
{
        struct gpio_poweroff *gpio_poweroff = data->cb_data;

        /* drive it active, also inactive->active edge */
        gpiod_direction_output(gpio_poweroff->reset_gpio, 1);
        mdelay(gpio_poweroff->active_delay_ms);

        /* drive inactive, also active->inactive edge */
        gpiod_set_value_cansleep(gpio_poweroff->reset_gpio, 0);
        mdelay(gpio_poweroff->inactive_delay_ms);

        /* drive it active, also inactive->active edge */
        gpiod_set_value_cansleep(gpio_poweroff->reset_gpio, 1);

        /* give it some time */
        mdelay(gpio_poweroff->timeout_ms);

        /*
         * If code reaches this point, it means that gpio-poweroff has failed
         * to actually power off the system.
         * Warn the user that the attempt to poweroff via gpio-poweroff
         * has gone wrong.
         */
        WARN(1, "Failed to poweroff via gpio-poweroff mechanism\n");

        return NOTIFY_DONE;
}

static int gpio_poweroff_probe(struct platform_device *pdev)
{
        struct gpio_poweroff *gpio_poweroff;
        bool input = false;
        enum gpiod_flags flags;
        int priority = SYS_OFF_PRIO_DEFAULT;
        int ret;

        gpio_poweroff = devm_kzalloc(&pdev->dev, sizeof(*gpio_poweroff), GFP_KERNEL);
        if (!gpio_poweroff)
                return -ENOMEM;

        input = device_property_read_bool(&pdev->dev, "input");
        if (input)
                flags = GPIOD_IN;
        else
                flags = GPIOD_OUT_LOW;


        gpio_poweroff->active_delay_ms = 100;
        gpio_poweroff->inactive_delay_ms = 100;
        gpio_poweroff->timeout_ms = DEFAULT_TIMEOUT_MS;

        device_property_read_u32(&pdev->dev, "active-delay-ms", &gpio_poweroff->active_delay_ms);
        device_property_read_u32(&pdev->dev, "inactive-delay-ms",
                                 &gpio_poweroff->inactive_delay_ms);
        device_property_read_u32(&pdev->dev, "timeout-ms", &gpio_poweroff->timeout_ms);
        device_property_read_u32(&pdev->dev, "priority", &priority);
        if (priority > 255) {
                dev_err(&pdev->dev, "Invalid priority property: %u\n", priority);
                return -EINVAL;
        }

        gpio_poweroff->reset_gpio = devm_gpiod_get(&pdev->dev, NULL, flags);
        if (IS_ERR(gpio_poweroff->reset_gpio))
                return PTR_ERR(gpio_poweroff->reset_gpio);

        ret = devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_POWER_OFF,
                                            priority, gpio_poweroff_do_poweroff, gpio_poweroff);
        if (ret)
                return dev_err_probe(&pdev->dev, ret, "Cannot register poweroff handler\n");

        return 0;
}

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

static struct platform_driver gpio_poweroff_driver = {
        .probe = gpio_poweroff_probe,
        .driver = {
                .name = "poweroff-gpio",
                .of_match_table = of_gpio_poweroff_match,
        },
};

module_platform_driver(gpio_poweroff_driver);

MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>");
MODULE_DESCRIPTION("GPIO poweroff driver");
MODULE_ALIAS("platform:poweroff-gpio");