// SPDX-License-Identifier: GPL-2.0-only
/*
 * Ralink RT288x/RT3xxx/MT76xx built-in hardware watchdog timer
 *
 * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
 * Copyright (C) 2013 John Crispin <john@phrozen.org>
 *
 * This driver was based on: drivers/watchdog/softdog.c
 */

#include <linux/clk.h>
#include <linux/reset.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/watchdog.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/mod_devicetable.h>

#include <asm/mach-ralink/ralink_regs.h>

#define SYSC_RSTSTAT                    0x38
#define WDT_RST_CAUSE                   BIT(1)

#define RALINK_WDT_TIMEOUT              30
#define RALINK_WDT_PRESCALE             65536

#define TIMER_REG_TMR1LOAD              0x00
#define TIMER_REG_TMR1CTL               0x08

#define TMRSTAT_TMR1RST                 BIT(5)

#define TMR1CTL_ENABLE                  BIT(7)
#define TMR1CTL_MODE_SHIFT              4
#define TMR1CTL_MODE_MASK               0x3
#define TMR1CTL_MODE_FREE_RUNNING       0x0
#define TMR1CTL_MODE_PERIODIC           0x1
#define TMR1CTL_MODE_TIMEOUT            0x2
#define TMR1CTL_MODE_WDT                0x3
#define TMR1CTL_PRESCALE_MASK           0xf
#define TMR1CTL_PRESCALE_65536          0xf

struct rt2880_wdt_data {
        void __iomem *base;
        unsigned long freq;
        struct clk *clk;
        struct reset_control *rst;
        struct watchdog_device wdt;
};

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 inline void rt_wdt_w32(void __iomem *base, unsigned int reg, u32 val)
{
        iowrite32(val, base + reg);
}

static inline u32 rt_wdt_r32(void __iomem *base, unsigned int reg)
{
        return ioread32(base + reg);
}

static int rt288x_wdt_ping(struct watchdog_device *w)
{
        struct rt2880_wdt_data *drvdata = watchdog_get_drvdata(w);

        rt_wdt_w32(drvdata->base, TIMER_REG_TMR1LOAD, w->timeout * drvdata->freq);

        return 0;
}

static int rt288x_wdt_start(struct watchdog_device *w)
{
        struct rt2880_wdt_data *drvdata = watchdog_get_drvdata(w);
        u32 t;

        t = rt_wdt_r32(drvdata->base, TIMER_REG_TMR1CTL);
        t &= ~(TMR1CTL_MODE_MASK << TMR1CTL_MODE_SHIFT |
                TMR1CTL_PRESCALE_MASK);
        t |= (TMR1CTL_MODE_WDT << TMR1CTL_MODE_SHIFT |
                TMR1CTL_PRESCALE_65536);
        rt_wdt_w32(drvdata->base, TIMER_REG_TMR1CTL, t);

        rt288x_wdt_ping(w);

        t = rt_wdt_r32(drvdata->base, TIMER_REG_TMR1CTL);
        t |= TMR1CTL_ENABLE;
        rt_wdt_w32(drvdata->base, TIMER_REG_TMR1CTL, t);

        return 0;
}

static int rt288x_wdt_stop(struct watchdog_device *w)
{
        struct rt2880_wdt_data *drvdata = watchdog_get_drvdata(w);
        u32 t;

        rt288x_wdt_ping(w);

        t = rt_wdt_r32(drvdata->base, TIMER_REG_TMR1CTL);
        t &= ~TMR1CTL_ENABLE;
        rt_wdt_w32(drvdata->base, TIMER_REG_TMR1CTL, t);

        return 0;
}

static int rt288x_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
{
        w->timeout = t;
        rt288x_wdt_ping(w);

        return 0;
}

static int rt288x_wdt_bootcause(void)
{
        if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE)
                return WDIOF_CARDRESET;

        return 0;
}

static const struct watchdog_info rt288x_wdt_info = {
        .identity = "Ralink Watchdog",
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
};

static const struct watchdog_ops rt288x_wdt_ops = {
        .owner = THIS_MODULE,
        .start = rt288x_wdt_start,
        .stop = rt288x_wdt_stop,
        .ping = rt288x_wdt_ping,
        .set_timeout = rt288x_wdt_set_timeout,
};

static int rt288x_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct watchdog_device *wdt;
        struct rt2880_wdt_data *drvdata;
        int ret;

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

        drvdata->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(drvdata->base))
                return PTR_ERR(drvdata->base);

        drvdata->clk = devm_clk_get(dev, NULL);
        if (IS_ERR(drvdata->clk))
                return PTR_ERR(drvdata->clk);

        drvdata->rst = devm_reset_control_get_exclusive(dev, NULL);
        if (!IS_ERR(drvdata->rst))
                reset_control_deassert(drvdata->rst);

        drvdata->freq = clk_get_rate(drvdata->clk) / RALINK_WDT_PRESCALE;

        wdt = &drvdata->wdt;
        wdt->info = &rt288x_wdt_info;
        wdt->ops = &rt288x_wdt_ops;
        wdt->min_timeout = 1;
        wdt->max_timeout = (0xfffful / drvdata->freq);
        wdt->parent = dev;
        wdt->bootstatus = rt288x_wdt_bootcause();

        watchdog_init_timeout(wdt, wdt->max_timeout, dev);
        watchdog_set_nowayout(wdt, nowayout);
        watchdog_set_drvdata(wdt, drvdata);

        watchdog_stop_on_reboot(wdt);
        ret = devm_watchdog_register_device(dev, &drvdata->wdt);
        if (!ret)
                dev_info(dev, "Initialized\n");

        return 0;
}

static const struct of_device_id rt288x_wdt_match[] = {
        { .compatible = "ralink,rt2880-wdt" },
        {},
};
MODULE_DEVICE_TABLE(of, rt288x_wdt_match);

static struct platform_driver rt288x_wdt_driver = {
        .probe          = rt288x_wdt_probe,
        .driver         = {
                .name           = KBUILD_MODNAME,
                .of_match_table = rt288x_wdt_match,
        },
};

module_platform_driver(rt288x_wdt_driver);

MODULE_DESCRIPTION("MediaTek/Ralink RT288x/RT3xxx hardware watchdog driver");
MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
MODULE_LICENSE("GPL v2");