// SPDX-License-Identifier: GPL-2.0-only
/*
 * Watchdog driver for Technologic Systems TS-72xx based SBCs
 * (TS-7200, TS-7250 and TS-7260). These boards have external
 * glue logic CPLD chip, which includes programmable watchdog
 * timer.
 *
 * Copyright (c) 2009 Mika Westerberg <mika.westerberg@iki.fi>
 *
 * This driver is based on ep93xx_wdt and wm831x_wdt drivers.
 *
 */

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

#define TS72XX_WDT_DEFAULT_TIMEOUT      30

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

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");

/* priv->control_reg */
#define TS72XX_WDT_CTRL_DISABLE         0x00
#define TS72XX_WDT_CTRL_250MS           0x01
#define TS72XX_WDT_CTRL_500MS           0x02
#define TS72XX_WDT_CTRL_1SEC            0x03
#define TS72XX_WDT_CTRL_RESERVED        0x04
#define TS72XX_WDT_CTRL_2SEC            0x05
#define TS72XX_WDT_CTRL_4SEC            0x06
#define TS72XX_WDT_CTRL_8SEC            0x07

/* priv->feed_reg */
#define TS72XX_WDT_FEED_VAL             0x05

struct ts72xx_wdt_priv {
        void __iomem    *control_reg;
        void __iomem    *feed_reg;
        struct watchdog_device wdd;
        unsigned char regval;
};

static int ts72xx_wdt_start(struct watchdog_device *wdd)
{
        struct ts72xx_wdt_priv *priv = watchdog_get_drvdata(wdd);

        writeb(TS72XX_WDT_FEED_VAL, priv->feed_reg);
        writeb(priv->regval, priv->control_reg);

        return 0;
}

static int ts72xx_wdt_stop(struct watchdog_device *wdd)
{
        struct ts72xx_wdt_priv *priv = watchdog_get_drvdata(wdd);

        writeb(TS72XX_WDT_FEED_VAL, priv->feed_reg);
        writeb(TS72XX_WDT_CTRL_DISABLE, priv->control_reg);

        return 0;
}

static int ts72xx_wdt_ping(struct watchdog_device *wdd)
{
        struct ts72xx_wdt_priv *priv = watchdog_get_drvdata(wdd);

        writeb(TS72XX_WDT_FEED_VAL, priv->feed_reg);

        return 0;
}

static int ts72xx_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
{
        struct ts72xx_wdt_priv *priv = watchdog_get_drvdata(wdd);

        if (to == 1) {
                priv->regval = TS72XX_WDT_CTRL_1SEC;
        } else if (to == 2) {
                priv->regval = TS72XX_WDT_CTRL_2SEC;
        } else if (to <= 4) {
                priv->regval = TS72XX_WDT_CTRL_4SEC;
                to = 4;
        } else {
                priv->regval = TS72XX_WDT_CTRL_8SEC;
                if (to <= 8)
                        to = 8;
        }

        wdd->timeout = to;

        if (watchdog_active(wdd)) {
                ts72xx_wdt_stop(wdd);
                ts72xx_wdt_start(wdd);
        }

        return 0;
}

static const struct watchdog_info ts72xx_wdt_ident = {
        .options                = WDIOF_KEEPALIVEPING |
                                  WDIOF_SETTIMEOUT |
                                  WDIOF_MAGICCLOSE,
        .firmware_version       = 1,
        .identity               = "TS-72XX WDT",
};

static const struct watchdog_ops ts72xx_wdt_ops = {
        .owner          = THIS_MODULE,
        .start          = ts72xx_wdt_start,
        .stop           = ts72xx_wdt_stop,
        .ping           = ts72xx_wdt_ping,
        .set_timeout    = ts72xx_wdt_settimeout,
};

static int ts72xx_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct ts72xx_wdt_priv *priv;
        struct watchdog_device *wdd;
        int ret;

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

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

        priv->feed_reg = devm_platform_ioremap_resource(pdev, 1);
        if (IS_ERR(priv->feed_reg))
                return PTR_ERR(priv->feed_reg);

        wdd = &priv->wdd;
        wdd->info = &ts72xx_wdt_ident;
        wdd->ops = &ts72xx_wdt_ops;
        wdd->min_timeout = 1;
        wdd->max_hw_heartbeat_ms = 8000;
        wdd->parent = dev;

        watchdog_set_nowayout(wdd, nowayout);

        wdd->timeout = TS72XX_WDT_DEFAULT_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, "TS-72xx Watchdog driver\n");

        return 0;
}

static const struct of_device_id ts72xx_wdt_of_ids[] = {
        { .compatible = "technologic,ts7200-wdt" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, ts72xx_wdt_of_ids);

static struct platform_driver ts72xx_wdt_driver = {
        .probe          = ts72xx_wdt_probe,
        .driver         = {
                .name   = "ts72xx-wdt",
                .of_match_table = ts72xx_wdt_of_ids,
        },
};

module_platform_driver(ts72xx_wdt_driver);

MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>");
MODULE_DESCRIPTION("TS-72xx SBC Watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ts72xx-wdt");