// SPDX-License-Identifier: GPL-2.0-only
/*
 * Watchdog driver for Cirrus Logic EP93xx family of devices.
 *
 * Copyright (c) 2004 Ray Lehtiniemi
 * Copyright (c) 2006 Tower Technologies
 * Based on ep93xx driver, bits from alim7101_wdt.c
 *
 * Authors: Ray Lehtiniemi <rayl@mail.com>,
 *      Alessandro Zummo <a.zummo@towertech.it>
 *
 * Copyright (c) 2012 H Hartley Sweeten <hsweeten@visionengravers.com>
 *      Convert to a platform device and use the watchdog framework API
 *
 * This watchdog fires after 250msec, which is a too short interval
 * for us to rely on the user space daemon alone. So we ping the
 * wdt each ~200msec and eventually stop doing it if the user space
 * daemon dies.
 */

#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/watchdog.h>
#include <linux/io.h>

/* default timeout (secs) */
#define WDT_TIMEOUT 30

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

static unsigned int timeout;
module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds.");

#define EP93XX_WATCHDOG         0x00
#define EP93XX_WDSTATUS         0x04

struct ep93xx_wdt_priv {
        void __iomem *mmio;
        struct watchdog_device wdd;
};

static int ep93xx_wdt_start(struct watchdog_device *wdd)
{
        struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);

        writel(0xaaaa, priv->mmio + EP93XX_WATCHDOG);

        return 0;
}

static int ep93xx_wdt_stop(struct watchdog_device *wdd)
{
        struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);

        writel(0xaa55, priv->mmio + EP93XX_WATCHDOG);

        return 0;
}

static int ep93xx_wdt_ping(struct watchdog_device *wdd)
{
        struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);

        writel(0x5555, priv->mmio + EP93XX_WATCHDOG);

        return 0;
}

static const struct watchdog_info ep93xx_wdt_ident = {
        .options        = WDIOF_CARDRESET |
                          WDIOF_SETTIMEOUT |
                          WDIOF_MAGICCLOSE |
                          WDIOF_KEEPALIVEPING,
        .identity       = "EP93xx Watchdog",
};

static const struct watchdog_ops ep93xx_wdt_ops = {
        .owner          = THIS_MODULE,
        .start          = ep93xx_wdt_start,
        .stop           = ep93xx_wdt_stop,
        .ping           = ep93xx_wdt_ping,
};

static int ep93xx_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct ep93xx_wdt_priv *priv;
        struct watchdog_device *wdd;
        unsigned long val;
        int ret;

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

        priv->mmio = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(priv->mmio))
                return PTR_ERR(priv->mmio);

        val = readl(priv->mmio + EP93XX_WATCHDOG);

        wdd = &priv->wdd;
        wdd->bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
        wdd->info = &ep93xx_wdt_ident;
        wdd->ops = &ep93xx_wdt_ops;
        wdd->min_timeout = 1;
        wdd->max_hw_heartbeat_ms = 200;
        wdd->parent = dev;

        watchdog_set_nowayout(wdd, nowayout);

        wdd->timeout = WDT_TIMEOUT;
        watchdog_init_timeout(wdd, timeout, dev);

        watchdog_set_drvdata(wdd, priv);

        ret = devm_watchdog_register_device(dev, wdd);
        if (ret)
                return ret;

        dev_info(dev, "EP93XX watchdog driver %s\n",
                 (val & 0x08) ? " (nCS1 disable detected)" : "");

        return 0;
}

static struct platform_driver ep93xx_wdt_driver = {
        .driver         = {
                .name   = "ep93xx-wdt",
        },
        .probe          = ep93xx_wdt_probe,
};

module_platform_driver(ep93xx_wdt_driver);

MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>");
MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
MODULE_DESCRIPTION("EP93xx Watchdog");
MODULE_LICENSE("GPL");