// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (C) 2010, Paul Cercueil <paul@crapouillou.net>
 *  JZ4740 Watchdog driver
 */

#include <linux/mfd/ingenic-tcu.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/device.h>
#include <linux/clk.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/regmap.h>

#define DEFAULT_HEARTBEAT 5
#define MAX_HEARTBEAT     2048

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

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

struct jz4740_wdt_drvdata {
        struct watchdog_device wdt;
        struct regmap *map;
        struct clk *clk;
        unsigned long clk_rate;
};

static int jz4740_wdt_ping(struct watchdog_device *wdt_dev)
{
        struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);

        regmap_write(drvdata->map, TCU_REG_WDT_TCNT, 0);

        return 0;
}

static int jz4740_wdt_set_timeout(struct watchdog_device *wdt_dev,
                                    unsigned int new_timeout)
{
        struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
        u16 timeout_value = (u16)(drvdata->clk_rate * new_timeout);
        unsigned int tcer;

        regmap_read(drvdata->map, TCU_REG_WDT_TCER, &tcer);
        regmap_write(drvdata->map, TCU_REG_WDT_TCER, 0);

        regmap_write(drvdata->map, TCU_REG_WDT_TDR, timeout_value);
        regmap_write(drvdata->map, TCU_REG_WDT_TCNT, 0);

        if (tcer & TCU_WDT_TCER_TCEN)
                regmap_write(drvdata->map, TCU_REG_WDT_TCER, TCU_WDT_TCER_TCEN);

        wdt_dev->timeout = new_timeout;
        return 0;
}

static int jz4740_wdt_start(struct watchdog_device *wdt_dev)
{
        struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
        unsigned int tcer;
        int ret;

        ret = clk_prepare_enable(drvdata->clk);
        if (ret)
                return ret;

        regmap_read(drvdata->map, TCU_REG_WDT_TCER, &tcer);

        jz4740_wdt_set_timeout(wdt_dev, wdt_dev->timeout);

        /* Start watchdog if it wasn't started already */
        if (!(tcer & TCU_WDT_TCER_TCEN))
                regmap_write(drvdata->map, TCU_REG_WDT_TCER, TCU_WDT_TCER_TCEN);

        return 0;
}

static int jz4740_wdt_stop(struct watchdog_device *wdt_dev)
{
        struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);

        regmap_write(drvdata->map, TCU_REG_WDT_TCER, 0);
        clk_disable_unprepare(drvdata->clk);

        return 0;
}

static int jz4740_wdt_restart(struct watchdog_device *wdt_dev,
                              unsigned long action, void *data)
{
        wdt_dev->timeout = 0;
        jz4740_wdt_start(wdt_dev);
        return 0;
}

static const struct watchdog_info jz4740_wdt_info = {
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
        .identity = "jz4740 Watchdog",
};

static const struct watchdog_ops jz4740_wdt_ops = {
        .owner = THIS_MODULE,
        .start = jz4740_wdt_start,
        .stop = jz4740_wdt_stop,
        .ping = jz4740_wdt_ping,
        .set_timeout = jz4740_wdt_set_timeout,
        .restart = jz4740_wdt_restart,
};

#ifdef CONFIG_OF
static const struct of_device_id jz4740_wdt_of_matches[] = {
        { .compatible = "ingenic,jz4740-watchdog", },
        { .compatible = "ingenic,jz4780-watchdog", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, jz4740_wdt_of_matches);
#endif

static int jz4740_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct jz4740_wdt_drvdata *drvdata;
        struct watchdog_device *jz4740_wdt;
        long rate;
        int ret;

        drvdata = devm_kzalloc(dev, sizeof(struct jz4740_wdt_drvdata),
                               GFP_KERNEL);
        if (!drvdata)
                return -ENOMEM;

        drvdata->clk = devm_clk_get(&pdev->dev, "wdt");
        if (IS_ERR(drvdata->clk)) {
                dev_err(&pdev->dev, "cannot find WDT clock\n");
                return PTR_ERR(drvdata->clk);
        }

        /* Set smallest clock possible */
        rate = clk_round_rate(drvdata->clk, 1);
        if (rate < 0)
                return rate;

        ret = clk_set_rate(drvdata->clk, rate);
        if (ret)
                return ret;

        drvdata->clk_rate = rate;
        jz4740_wdt = &drvdata->wdt;
        jz4740_wdt->info = &jz4740_wdt_info;
        jz4740_wdt->ops = &jz4740_wdt_ops;
        jz4740_wdt->min_timeout = 1;
        jz4740_wdt->max_timeout = 0xffff / rate;
        jz4740_wdt->timeout = clamp(heartbeat,
                                    jz4740_wdt->min_timeout,
                                    jz4740_wdt->max_timeout);
        jz4740_wdt->parent = dev;
        watchdog_set_nowayout(jz4740_wdt, nowayout);
        watchdog_set_drvdata(jz4740_wdt, drvdata);

        drvdata->map = device_node_to_regmap(dev->parent->of_node);
        if (IS_ERR(drvdata->map)) {
                dev_err(dev, "regmap not found\n");
                return PTR_ERR(drvdata->map);
        }

        return devm_watchdog_register_device(dev, &drvdata->wdt);
}

static struct platform_driver jz4740_wdt_driver = {
        .probe = jz4740_wdt_probe,
        .driver = {
                .name = "jz4740-wdt",
                .of_match_table = of_match_ptr(jz4740_wdt_of_matches),
        },
};

module_platform_driver(jz4740_wdt_driver);

MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
MODULE_DESCRIPTION("jz4740 Watchdog Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:jz4740-wdt");