// SPDX-License-Identifier: GPL-2.0+
/*
 * Watchdog driver for TQMx86 PLD.
 *
 * The watchdog supports power of 2 timeouts from 1 to 4096sec.
 * Once started, it cannot be stopped.
 *
 * Based on the vendor code written by Vadim V.Vlasov
 * <vvlasov@dev.rtsoft.ru>
 */

#include <linux/io.h>
#include <linux/log2.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/timer.h>
#include <linux/watchdog.h>

/* default timeout (secs) */
#define WDT_TIMEOUT 32

static unsigned int timeout;
module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout,
        "Watchdog timeout in seconds. (1<=timeout<=4096, default="
                                __MODULE_STRING(WDT_TIMEOUT) ")");
struct tqmx86_wdt {
        struct watchdog_device wdd;
        void __iomem *io_base;
};

#define TQMX86_WDCFG    0x00 /* Watchdog Configuration Register */
#define TQMX86_WDCS     0x01 /* Watchdog Config/Status Register */

static int tqmx86_wdt_start(struct watchdog_device *wdd)
{
        struct tqmx86_wdt *priv = watchdog_get_drvdata(wdd);

        iowrite8(0x81, priv->io_base + TQMX86_WDCS);

        return 0;
}

static int tqmx86_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
{
        struct tqmx86_wdt *priv = watchdog_get_drvdata(wdd);
        u8 val;

        t = roundup_pow_of_two(t);
        val = ilog2(t) | 0x90;
        val += 3; /* values 0,1,2 correspond to 0.125,0.25,0.5s timeouts */
        iowrite8(val, priv->io_base + TQMX86_WDCFG);

        wdd->timeout = t;

        return 0;
}

static const struct watchdog_info tqmx86_wdt_info = {
        .options        = WDIOF_SETTIMEOUT |
                          WDIOF_KEEPALIVEPING,
        .identity       = "TQMx86 Watchdog",
};

static const struct watchdog_ops tqmx86_wdt_ops = {
        .owner          = THIS_MODULE,
        .start          = tqmx86_wdt_start,
        .set_timeout    = tqmx86_wdt_set_timeout,
};

static int tqmx86_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct tqmx86_wdt *priv;
        struct resource *res;
        int err;

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

        res = platform_get_resource(pdev, IORESOURCE_IO, 0);
        if (!res)
                return -ENODEV;

        priv->io_base = devm_ioport_map(dev, res->start, resource_size(res));
        if (!priv->io_base)
                return -ENOMEM;

        watchdog_set_drvdata(&priv->wdd, priv);

        priv->wdd.parent = dev;
        priv->wdd.info = &tqmx86_wdt_info;
        priv->wdd.ops = &tqmx86_wdt_ops;
        priv->wdd.min_timeout = 1;
        priv->wdd.max_timeout = 4096;
        priv->wdd.max_hw_heartbeat_ms = 4096*1000;
        priv->wdd.timeout = WDT_TIMEOUT;

        watchdog_init_timeout(&priv->wdd, timeout, dev);
        watchdog_set_nowayout(&priv->wdd, WATCHDOG_NOWAYOUT);

        tqmx86_wdt_set_timeout(&priv->wdd, priv->wdd.timeout);

        err = devm_watchdog_register_device(dev, &priv->wdd);
        if (err)
                return err;

        dev_info(dev, "TQMx86 watchdog\n");

        return 0;
}

static struct platform_driver tqmx86_wdt_driver = {
        .driver         = {
                .name   = "tqmx86-wdt",
        },
        .probe          = tqmx86_wdt_probe,
};

module_platform_driver(tqmx86_wdt_driver);

MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
MODULE_DESCRIPTION("TQMx86 Watchdog");
MODULE_ALIAS("platform:tqmx86-wdt");
MODULE_LICENSE("GPL");