// SPDX-License-Identifier: GPL-2.0+
/*
 * Watchdog driver for the wm831x PMICs
 *
 * Copyright (C) 2009 Wolfson Microelectronics
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/uaccess.h>

#include <linux/mfd/wm831x/core.h>
#include <linux/mfd/wm831x/pdata.h>
#include <linux/mfd/wm831x/watchdog.h>

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) ")");

struct wm831x_wdt_drvdata {
        struct watchdog_device wdt;
        struct wm831x *wm831x;
        struct mutex lock;
        int update_state;
};

/* We can't use the sub-second values here but they're included
 * for completeness.  */
static struct {
        unsigned int time;  /* Seconds */
        u16 val;            /* WDOG_TO value */
} wm831x_wdt_cfgs[] = {
        {  1, 2 },
        {  2, 3 },
        {  4, 4 },
        {  8, 5 },
        { 16, 6 },
        { 32, 7 },
        { 33, 7 },  /* Actually 32.768s so include both, others round down */
};

static int wm831x_wdt_start(struct watchdog_device *wdt_dev)
{
        struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
        struct wm831x *wm831x = driver_data->wm831x;
        int ret;

        mutex_lock(&driver_data->lock);

        ret = wm831x_reg_unlock(wm831x);
        if (ret == 0) {
                ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
                                      WM831X_WDOG_ENA, WM831X_WDOG_ENA);
                wm831x_reg_lock(wm831x);
        } else {
                dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
                        ret);
        }

        mutex_unlock(&driver_data->lock);

        return ret;
}

static int wm831x_wdt_stop(struct watchdog_device *wdt_dev)
{
        struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
        struct wm831x *wm831x = driver_data->wm831x;
        int ret;

        mutex_lock(&driver_data->lock);

        ret = wm831x_reg_unlock(wm831x);
        if (ret == 0) {
                ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
                                      WM831X_WDOG_ENA, 0);
                wm831x_reg_lock(wm831x);
        } else {
                dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
                        ret);
        }

        mutex_unlock(&driver_data->lock);

        return ret;
}

static int wm831x_wdt_ping(struct watchdog_device *wdt_dev)
{
        struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
        struct wm831x *wm831x = driver_data->wm831x;
        int ret;
        u16 reg;

        mutex_lock(&driver_data->lock);

        reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);

        if (!(reg & WM831X_WDOG_RST_SRC)) {
                dev_err(wm831x->dev, "Hardware watchdog update unsupported\n");
                ret = -EINVAL;
                goto out;
        }

        reg |= WM831X_WDOG_RESET;

        ret = wm831x_reg_unlock(wm831x);
        if (ret == 0) {
                ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
                wm831x_reg_lock(wm831x);
        } else {
                dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
                        ret);
        }

out:
        mutex_unlock(&driver_data->lock);

        return ret;
}

static int wm831x_wdt_set_timeout(struct watchdog_device *wdt_dev,
                                  unsigned int timeout)
{
        struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
        struct wm831x *wm831x = driver_data->wm831x;
        int ret, i;

        for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
                if (wm831x_wdt_cfgs[i].time == timeout)
                        break;
        if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
                return -EINVAL;

        ret = wm831x_reg_unlock(wm831x);
        if (ret == 0) {
                ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
                                      WM831X_WDOG_TO_MASK,
                                      wm831x_wdt_cfgs[i].val);
                wm831x_reg_lock(wm831x);
        } else {
                dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
                        ret);
        }

        wdt_dev->timeout = timeout;

        return ret;
}

static const struct watchdog_info wm831x_wdt_info = {
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
        .identity = "WM831x Watchdog",
};

static const struct watchdog_ops wm831x_wdt_ops = {
        .owner = THIS_MODULE,
        .start = wm831x_wdt_start,
        .stop = wm831x_wdt_stop,
        .ping = wm831x_wdt_ping,
        .set_timeout = wm831x_wdt_set_timeout,
};

static int wm831x_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct wm831x *wm831x = dev_get_drvdata(dev->parent);
        struct wm831x_pdata *chip_pdata = dev_get_platdata(dev->parent);
        struct wm831x_watchdog_pdata *pdata;
        struct wm831x_wdt_drvdata *driver_data;
        struct watchdog_device *wm831x_wdt;
        int reg, ret, i;

        ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
        if (ret < 0) {
                dev_err(wm831x->dev, "Failed to read watchdog status: %d\n",
                        ret);
                return ret;
        }
        reg = ret;

        if (reg & WM831X_WDOG_DEBUG)
                dev_warn(wm831x->dev, "Watchdog is paused\n");

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

        mutex_init(&driver_data->lock);
        driver_data->wm831x = wm831x;

        wm831x_wdt = &driver_data->wdt;

        wm831x_wdt->info = &wm831x_wdt_info;
        wm831x_wdt->ops = &wm831x_wdt_ops;
        wm831x_wdt->parent = dev;
        watchdog_set_nowayout(wm831x_wdt, nowayout);
        watchdog_set_drvdata(wm831x_wdt, driver_data);

        reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
        reg &= WM831X_WDOG_TO_MASK;
        for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
                if (wm831x_wdt_cfgs[i].val == reg)
                        break;
        if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
                dev_warn(wm831x->dev,
                         "Unknown watchdog timeout: %x\n", reg);
        else
                wm831x_wdt->timeout = wm831x_wdt_cfgs[i].time;

        /* Apply any configuration */
        if (chip_pdata)
                pdata = chip_pdata->watchdog;
        else
                pdata = NULL;

        if (pdata) {
                reg &= ~(WM831X_WDOG_SECACT_MASK | WM831X_WDOG_PRIMACT_MASK |
                         WM831X_WDOG_RST_SRC);

                reg |= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT;
                reg |= pdata->secondary << WM831X_WDOG_SECACT_SHIFT;
                reg |= pdata->software << WM831X_WDOG_RST_SRC_SHIFT;

                ret = wm831x_reg_unlock(wm831x);
                if (ret == 0) {
                        ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
                        wm831x_reg_lock(wm831x);
                } else {
                        dev_err(wm831x->dev,
                                "Failed to unlock security key: %d\n", ret);
                        return ret;
                }
        }

        return devm_watchdog_register_device(dev, &driver_data->wdt);
}

static struct platform_driver wm831x_wdt_driver = {
        .probe = wm831x_wdt_probe,
        .driver = {
                .name = "wm831x-watchdog",
        },
};

module_platform_driver(wm831x_wdt_driver);

MODULE_AUTHOR("Mark Brown");
MODULE_DESCRIPTION("WM831x Watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:wm831x-watchdog");