// SPDX-License-Identifier: GPL-2.0
/*
 * Watchdog driver for the RTC based watchdog in STMP3xxx and i.MX23/28
 *
 * Author: Wolfram Sang <kernel@pengutronix.de>
 *
 * Copyright (C) 2011-12 Wolfram Sang, Pengutronix
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>
#include <linux/stmp3xxx_rtc_wdt.h>
#include <linux/notifier.h>
#include <linux/reboot.h>

#define WDOG_TICK_RATE 1000 /* 1 kHz clock */
#define STMP3XXX_DEFAULT_TIMEOUT 19
#define STMP3XXX_MAX_TIMEOUT (UINT_MAX / WDOG_TICK_RATE)

static int heartbeat = STMP3XXX_DEFAULT_TIMEOUT;
module_param(heartbeat, uint, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat period in seconds from 1 to "
                 __MODULE_STRING(STMP3XXX_MAX_TIMEOUT) ", default "
                 __MODULE_STRING(STMP3XXX_DEFAULT_TIMEOUT));

static int wdt_start(struct watchdog_device *wdd)
{
        struct device *dev = watchdog_get_drvdata(wdd);
        struct stmp3xxx_wdt_pdata *pdata = dev_get_platdata(dev);

        pdata->wdt_set_timeout(dev->parent, wdd->timeout * WDOG_TICK_RATE);
        return 0;
}

static int wdt_stop(struct watchdog_device *wdd)
{
        struct device *dev = watchdog_get_drvdata(wdd);
        struct stmp3xxx_wdt_pdata *pdata = dev_get_platdata(dev);

        pdata->wdt_set_timeout(dev->parent, 0);
        return 0;
}

static int wdt_set_timeout(struct watchdog_device *wdd, unsigned new_timeout)
{
        wdd->timeout = new_timeout;
        return wdt_start(wdd);
}

static const struct watchdog_info stmp3xxx_wdt_ident = {
        .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
        .identity = "STMP3XXX RTC Watchdog",
};

static const struct watchdog_ops stmp3xxx_wdt_ops = {
        .owner = THIS_MODULE,
        .start = wdt_start,
        .stop = wdt_stop,
        .set_timeout = wdt_set_timeout,
};

static struct watchdog_device stmp3xxx_wdd = {
        .info = &stmp3xxx_wdt_ident,
        .ops = &stmp3xxx_wdt_ops,
        .min_timeout = 1,
        .max_timeout = STMP3XXX_MAX_TIMEOUT,
        .status = WATCHDOG_NOWAYOUT_INIT_STATUS,
};

static int wdt_notify_sys(struct notifier_block *nb, unsigned long code,
                          void *unused)
{
        switch (code) {
        case SYS_DOWN:  /* keep enabled, system might crash while going down */
                break;
        case SYS_HALT:  /* allow the system to actually halt */
        case SYS_POWER_OFF:
                wdt_stop(&stmp3xxx_wdd);
                break;
        }

        return NOTIFY_DONE;
}

static struct notifier_block wdt_notifier = {
        .notifier_call = wdt_notify_sys,
};

static int stmp3xxx_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        int ret;

        watchdog_set_drvdata(&stmp3xxx_wdd, dev);

        stmp3xxx_wdd.timeout = clamp_t(unsigned, heartbeat, 1, STMP3XXX_MAX_TIMEOUT);
        stmp3xxx_wdd.parent = dev;

        ret = devm_watchdog_register_device(dev, &stmp3xxx_wdd);
        if (ret < 0)
                return ret;

        if (register_reboot_notifier(&wdt_notifier))
                dev_warn(dev, "cannot register reboot notifier\n");

        dev_info(dev, "initialized watchdog with heartbeat %ds\n",
                 stmp3xxx_wdd.timeout);
        return 0;
}

static void stmp3xxx_wdt_remove(struct platform_device *pdev)
{
        unregister_reboot_notifier(&wdt_notifier);
}

static int __maybe_unused stmp3xxx_wdt_suspend(struct device *dev)
{
        struct watchdog_device *wdd = &stmp3xxx_wdd;

        if (watchdog_active(wdd))
                return wdt_stop(wdd);

        return 0;
}

static int __maybe_unused stmp3xxx_wdt_resume(struct device *dev)
{
        struct watchdog_device *wdd = &stmp3xxx_wdd;

        if (watchdog_active(wdd))
                return wdt_start(wdd);

        return 0;
}

static SIMPLE_DEV_PM_OPS(stmp3xxx_wdt_pm_ops,
                         stmp3xxx_wdt_suspend, stmp3xxx_wdt_resume);

static struct platform_driver stmp3xxx_wdt_driver = {
        .driver = {
                .name = "stmp3xxx_rtc_wdt",
                .pm = &stmp3xxx_wdt_pm_ops,
        },
        .probe = stmp3xxx_wdt_probe,
        .remove = stmp3xxx_wdt_remove,
};
module_platform_driver(stmp3xxx_wdt_driver);

MODULE_DESCRIPTION("STMP3XXX RTC Watchdog Driver");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");