// SPDX-License-Identifier: GPL-2.0+
/*
 * Retu watchdog driver
 *
 * Copyright (C) 2004, 2005 Nokia Corporation
 *
 * Based on code written by Amit Kucheria and Michael Buesch.
 * Rewritten by Aaro Koskinen.
 */

#include <linux/devm-helpers.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mfd/retu.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>

/* Watchdog timer values in seconds */
#define RETU_WDT_MAX_TIMER      63

struct retu_wdt_dev {
        struct retu_dev         *rdev;
        struct device           *dev;
        struct delayed_work     ping_work;
};

/*
 * Since Retu watchdog cannot be disabled in hardware, we must kick it
 * with a timer until userspace watchdog software takes over. If
 * CONFIG_WATCHDOG_NOWAYOUT is set, we never start the feeding.
 */
static void retu_wdt_ping_enable(struct retu_wdt_dev *wdev)
{
        retu_write(wdev->rdev, RETU_REG_WATCHDOG, RETU_WDT_MAX_TIMER);
        schedule_delayed_work(&wdev->ping_work,
                        round_jiffies_relative(RETU_WDT_MAX_TIMER * HZ / 2));
}

static void retu_wdt_ping_disable(struct retu_wdt_dev *wdev)
{
        retu_write(wdev->rdev, RETU_REG_WATCHDOG, RETU_WDT_MAX_TIMER);
        cancel_delayed_work_sync(&wdev->ping_work);
}

static void retu_wdt_ping_work(struct work_struct *work)
{
        struct retu_wdt_dev *wdev = container_of(to_delayed_work(work),
                                                struct retu_wdt_dev, ping_work);
        retu_wdt_ping_enable(wdev);
}

static int retu_wdt_start(struct watchdog_device *wdog)
{
        struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);

        retu_wdt_ping_disable(wdev);

        return retu_write(wdev->rdev, RETU_REG_WATCHDOG, wdog->timeout);
}

static int retu_wdt_stop(struct watchdog_device *wdog)
{
        struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);

        retu_wdt_ping_enable(wdev);

        return 0;
}

static int retu_wdt_ping(struct watchdog_device *wdog)
{
        struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);

        return retu_write(wdev->rdev, RETU_REG_WATCHDOG, wdog->timeout);
}

static int retu_wdt_set_timeout(struct watchdog_device *wdog,
                                unsigned int timeout)
{
        struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);

        wdog->timeout = timeout;
        return retu_write(wdev->rdev, RETU_REG_WATCHDOG, wdog->timeout);
}

static const struct watchdog_info retu_wdt_info = {
        .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
        .identity = "Retu watchdog",
};

static const struct watchdog_ops retu_wdt_ops = {
        .owner          = THIS_MODULE,
        .start          = retu_wdt_start,
        .stop           = retu_wdt_stop,
        .ping           = retu_wdt_ping,
        .set_timeout    = retu_wdt_set_timeout,
};

static int retu_wdt_probe(struct platform_device *pdev)
{
        struct retu_dev *rdev = dev_get_drvdata(pdev->dev.parent);
        bool nowayout = WATCHDOG_NOWAYOUT;
        struct watchdog_device *retu_wdt;
        struct retu_wdt_dev *wdev;
        int ret;

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

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

        retu_wdt->info          = &retu_wdt_info;
        retu_wdt->ops           = &retu_wdt_ops;
        retu_wdt->timeout       = RETU_WDT_MAX_TIMER;
        retu_wdt->min_timeout   = 0;
        retu_wdt->max_timeout   = RETU_WDT_MAX_TIMER;
        retu_wdt->parent        = &pdev->dev;

        watchdog_set_drvdata(retu_wdt, wdev);
        watchdog_set_nowayout(retu_wdt, nowayout);

        wdev->rdev              = rdev;
        wdev->dev               = &pdev->dev;

        ret = devm_delayed_work_autocancel(&pdev->dev, &wdev->ping_work,
                                           retu_wdt_ping_work);
        if (ret)
                return ret;

        ret = devm_watchdog_register_device(&pdev->dev, retu_wdt);
        if (ret < 0)
                return ret;

        if (nowayout)
                retu_wdt_ping(retu_wdt);
        else
                retu_wdt_ping_enable(wdev);

        return 0;
}

static struct platform_driver retu_wdt_driver = {
        .probe          = retu_wdt_probe,
        .driver         = {
                .name   = "retu-wdt",
        },
};
module_platform_driver(retu_wdt_driver);

MODULE_ALIAS("platform:retu-wdt");
MODULE_DESCRIPTION("Retu watchdog");
MODULE_AUTHOR("Amit Kucheria");
MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
MODULE_LICENSE("GPL");