// SPDX-License-Identifier: GPL-2.0+
/*
 * Realtek RTD129x watchdog
 *
 * Copyright (c) 2017 Andreas Färber
 *
 */

#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>

#define RTD119X_TCWCR           0x0
#define RTD119X_TCWTR           0x4
#define RTD119X_TCWOV           0xc

#define RTD119X_TCWCR_WDEN_DISABLED             0xa5
#define RTD119X_TCWCR_WDEN_ENABLED              0xff
#define RTD119X_TCWCR_WDEN_MASK                 0xff

#define RTD119X_TCWTR_WDCLR                     BIT(0)

struct rtd119x_watchdog_device {
        struct watchdog_device wdt_dev;
        void __iomem *base;
        struct clk *clk;
};

static int rtd119x_wdt_start(struct watchdog_device *wdev)
{
        struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
        u32 val;

        val = readl_relaxed(data->base + RTD119X_TCWCR);
        val &= ~RTD119X_TCWCR_WDEN_MASK;
        val |= RTD119X_TCWCR_WDEN_ENABLED;
        writel(val, data->base + RTD119X_TCWCR);

        return 0;
}

static int rtd119x_wdt_stop(struct watchdog_device *wdev)
{
        struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
        u32 val;

        val = readl_relaxed(data->base + RTD119X_TCWCR);
        val &= ~RTD119X_TCWCR_WDEN_MASK;
        val |= RTD119X_TCWCR_WDEN_DISABLED;
        writel(val, data->base + RTD119X_TCWCR);

        return 0;
}

static int rtd119x_wdt_ping(struct watchdog_device *wdev)
{
        struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);

        writel_relaxed(RTD119X_TCWTR_WDCLR, data->base + RTD119X_TCWTR);

        return rtd119x_wdt_start(wdev);
}

static int rtd119x_wdt_set_timeout(struct watchdog_device *wdev, unsigned int val)
{
        struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);

        writel(val * clk_get_rate(data->clk), data->base + RTD119X_TCWOV);

        data->wdt_dev.timeout = val;

        return 0;
}

static const struct watchdog_ops rtd119x_wdt_ops = {
        .owner = THIS_MODULE,
        .start          = rtd119x_wdt_start,
        .stop           = rtd119x_wdt_stop,
        .ping           = rtd119x_wdt_ping,
        .set_timeout    = rtd119x_wdt_set_timeout,
};

static const struct watchdog_info rtd119x_wdt_info = {
        .identity = "rtd119x-wdt",
        .options = 0,
};

static const struct of_device_id rtd119x_wdt_dt_ids[] = {
         { .compatible = "realtek,rtd1295-watchdog" },
         { }
};

static int rtd119x_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct rtd119x_watchdog_device *data;

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

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

        data->clk = devm_clk_get_enabled(dev, NULL);
        if (IS_ERR(data->clk))
                return PTR_ERR(data->clk);

        data->wdt_dev.info = &rtd119x_wdt_info;
        data->wdt_dev.ops = &rtd119x_wdt_ops;
        data->wdt_dev.timeout = 120;
        data->wdt_dev.max_timeout = 0xffffffff / clk_get_rate(data->clk);
        data->wdt_dev.min_timeout = 1;
        data->wdt_dev.parent = dev;

        watchdog_stop_on_reboot(&data->wdt_dev);
        watchdog_set_drvdata(&data->wdt_dev, data);
        platform_set_drvdata(pdev, data);

        writel_relaxed(RTD119X_TCWTR_WDCLR, data->base + RTD119X_TCWTR);
        rtd119x_wdt_set_timeout(&data->wdt_dev, data->wdt_dev.timeout);
        rtd119x_wdt_stop(&data->wdt_dev);

        return devm_watchdog_register_device(dev, &data->wdt_dev);
}

static struct platform_driver rtd119x_wdt_driver = {
        .probe = rtd119x_wdt_probe,
        .driver = {
                .name = "rtd1295-watchdog",
                .of_match_table = rtd119x_wdt_dt_ids,
        },
};
builtin_platform_driver(rtd119x_wdt_driver);