// SPDX-License-Identifier: GPL-2.0-only
/*
 * Watchdog driver for Ricoh RN5T618 PMIC
 *
 * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com>
 */

#include <linux/device.h>
#include <linux/mfd/rn5t618.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>

#define DRIVER_NAME "rn5t618-wdt"

static bool nowayout = WATCHDOG_NOWAYOUT;
static unsigned int timeout;

module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds");

module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

struct rn5t618_wdt {
        struct watchdog_device wdt_dev;
        struct rn5t618 *rn5t618;
};

/*
 * This array encodes the values of WDOGTIM field for the supported
 * watchdog expiration times. If the watchdog is not accessed before
 * the timer expiration, the PMU generates an interrupt and if the CPU
 * doesn't clear it within one second the system is restarted.
 */
static const struct {
        u8 reg_val;
        unsigned int time;
} rn5t618_wdt_map[] = {
        { 0, 1 },
        { 1, 8 },
        { 2, 32 },
        { 3, 128 },
};

static int rn5t618_wdt_set_timeout(struct watchdog_device *wdt_dev,
                                   unsigned int t)
{
        struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
        int ret, i;

        for (i = 0; i < ARRAY_SIZE(rn5t618_wdt_map); i++) {
                if (rn5t618_wdt_map[i].time + 1 >= t)
                        break;
        }

        if (i == ARRAY_SIZE(rn5t618_wdt_map))
                return -EINVAL;

        ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
                                 RN5T618_WATCHDOG_WDOGTIM_M,
                                 rn5t618_wdt_map[i].reg_val);
        if (!ret)
                wdt_dev->timeout = rn5t618_wdt_map[i].time;

        return ret;
}

static int rn5t618_wdt_start(struct watchdog_device *wdt_dev)
{
        struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
        int ret;

        ret = rn5t618_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
        if (ret)
                return ret;

        /* enable repower-on */
        ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_REPCNT,
                                 RN5T618_REPCNT_REPWRON,
                                 RN5T618_REPCNT_REPWRON);
        if (ret)
                return ret;

        /* enable watchdog */
        ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
                                 RN5T618_WATCHDOG_WDOGEN,
                                 RN5T618_WATCHDOG_WDOGEN);
        if (ret)
                return ret;

        /* enable watchdog interrupt */
        return regmap_update_bits(wdt->rn5t618->regmap, RN5T618_PWRIREN,
                                  RN5T618_PWRIRQ_IR_WDOG,
                                  RN5T618_PWRIRQ_IR_WDOG);
}

static int rn5t618_wdt_stop(struct watchdog_device *wdt_dev)
{
        struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);

        return regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
                                  RN5T618_WATCHDOG_WDOGEN, 0);
}

static int rn5t618_wdt_ping(struct watchdog_device *wdt_dev)
{
        struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
        unsigned int val;
        int ret;

        /* The counter is restarted after a R/W access to watchdog register */
        ret = regmap_read(wdt->rn5t618->regmap, RN5T618_WATCHDOG, &val);
        if (ret)
                return ret;

        ret = regmap_write(wdt->rn5t618->regmap, RN5T618_WATCHDOG, val);
        if (ret)
                return ret;

        /* Clear pending watchdog interrupt */
        return regmap_update_bits(wdt->rn5t618->regmap, RN5T618_PWRIRQ,
                                  RN5T618_PWRIRQ_IR_WDOG, 0);
}

static const struct watchdog_info rn5t618_wdt_info = {
        .options        = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
                          WDIOF_KEEPALIVEPING,
        .identity       = DRIVER_NAME,
};

static const struct watchdog_ops rn5t618_wdt_ops = {
        .owner          = THIS_MODULE,
        .start          = rn5t618_wdt_start,
        .stop           = rn5t618_wdt_stop,
        .ping           = rn5t618_wdt_ping,
        .set_timeout    = rn5t618_wdt_set_timeout,
};

static int rn5t618_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct rn5t618 *rn5t618 = dev_get_drvdata(dev->parent);
        struct rn5t618_wdt *wdt;
        int min_timeout, max_timeout;

        wdt = devm_kzalloc(dev, sizeof(struct rn5t618_wdt), GFP_KERNEL);
        if (!wdt)
                return -ENOMEM;

        min_timeout = rn5t618_wdt_map[0].time;
        max_timeout = rn5t618_wdt_map[ARRAY_SIZE(rn5t618_wdt_map) - 1].time;

        wdt->rn5t618 = rn5t618;
        wdt->wdt_dev.info = &rn5t618_wdt_info;
        wdt->wdt_dev.ops = &rn5t618_wdt_ops;
        wdt->wdt_dev.min_timeout = min_timeout;
        wdt->wdt_dev.max_timeout = max_timeout;
        wdt->wdt_dev.timeout = max_timeout;
        wdt->wdt_dev.parent = dev;

        watchdog_set_drvdata(&wdt->wdt_dev, wdt);
        watchdog_init_timeout(&wdt->wdt_dev, timeout, dev);
        watchdog_set_nowayout(&wdt->wdt_dev, nowayout);

        platform_set_drvdata(pdev, wdt);

        return watchdog_register_device(&wdt->wdt_dev);
}

static int rn5t618_wdt_remove(struct platform_device *pdev)
{
        struct rn5t618_wdt *wdt = platform_get_drvdata(pdev);

        watchdog_unregister_device(&wdt->wdt_dev);

        return 0;
}

static struct platform_driver rn5t618_wdt_driver = {
        .probe = rn5t618_wdt_probe,
        .remove = rn5t618_wdt_remove,
        .driver = {
                .name   = DRIVER_NAME,
        },
};

module_platform_driver(rn5t618_wdt_driver);

MODULE_ALIAS("platform:rn5t618-wdt");
MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
MODULE_DESCRIPTION("RN5T618 watchdog driver");
MODULE_LICENSE("GPL v2");