// SPDX-License-Identifier: GPL-2.0
// Copyright (C) STMicroelectronics 2018
// Author: Pascal Paillet <p.paillet@st.com> for STMicroelectronics.

#include <linux/kernel.h>
#include <linux/mfd/stpmic1.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/watchdog.h>

/* WATCHDOG CONTROL REGISTER bit */
#define WDT_START               BIT(0)
#define WDT_PING                BIT(1)
#define WDT_START_MASK          BIT(0)
#define WDT_PING_MASK           BIT(1)
#define WDT_STOP                0

#define PMIC_WDT_MIN_TIMEOUT 1
#define PMIC_WDT_MAX_TIMEOUT 256
#define PMIC_WDT_DEFAULT_TIMEOUT 30

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 stpmic1_wdt {
        struct stpmic1 *pmic;
        struct watchdog_device wdtdev;
};

static int pmic_wdt_start(struct watchdog_device *wdd)
{
        struct stpmic1_wdt *wdt = watchdog_get_drvdata(wdd);

        return regmap_update_bits(wdt->pmic->regmap,
                                  WCHDG_CR, WDT_START_MASK, WDT_START);
}

static int pmic_wdt_stop(struct watchdog_device *wdd)
{
        struct stpmic1_wdt *wdt = watchdog_get_drvdata(wdd);

        return regmap_update_bits(wdt->pmic->regmap,
                                  WCHDG_CR, WDT_START_MASK, WDT_STOP);
}

static int pmic_wdt_ping(struct watchdog_device *wdd)
{
        struct stpmic1_wdt *wdt = watchdog_get_drvdata(wdd);

        return regmap_update_bits(wdt->pmic->regmap,
                                  WCHDG_CR, WDT_PING_MASK, WDT_PING);
}

static int pmic_wdt_set_timeout(struct watchdog_device *wdd,
                                unsigned int timeout)
{
        struct stpmic1_wdt *wdt = watchdog_get_drvdata(wdd);

        wdd->timeout = timeout;
        /* timeout is equal to register value + 1 */
        return regmap_write(wdt->pmic->regmap, WCHDG_TIMER_CR, timeout - 1);
}

static const struct watchdog_info pmic_watchdog_info = {
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
        .identity = "STPMIC1 PMIC Watchdog",
};

static const struct watchdog_ops pmic_watchdog_ops = {
        .owner = THIS_MODULE,
        .start = pmic_wdt_start,
        .stop = pmic_wdt_stop,
        .ping = pmic_wdt_ping,
        .set_timeout = pmic_wdt_set_timeout,
};

static int pmic_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        int ret;
        struct stpmic1 *pmic;
        struct stpmic1_wdt *wdt;

        if (!dev->parent)
                return -EINVAL;

        pmic = dev_get_drvdata(dev->parent);
        if (!pmic)
                return -EINVAL;

        wdt = devm_kzalloc(dev, sizeof(struct stpmic1_wdt), GFP_KERNEL);
        if (!wdt)
                return -ENOMEM;

        wdt->pmic = pmic;

        wdt->wdtdev.info = &pmic_watchdog_info;
        wdt->wdtdev.ops = &pmic_watchdog_ops;
        wdt->wdtdev.min_timeout = PMIC_WDT_MIN_TIMEOUT;
        wdt->wdtdev.max_timeout = PMIC_WDT_MAX_TIMEOUT;
        wdt->wdtdev.parent = dev;

        wdt->wdtdev.timeout = PMIC_WDT_DEFAULT_TIMEOUT;
        watchdog_init_timeout(&wdt->wdtdev, 0, dev);

        watchdog_set_nowayout(&wdt->wdtdev, nowayout);
        watchdog_set_drvdata(&wdt->wdtdev, wdt);

        ret = devm_watchdog_register_device(dev, &wdt->wdtdev);
        if (ret)
                return ret;

        dev_dbg(wdt->pmic->dev, "PMIC Watchdog driver probed\n");
        return 0;
}

static const struct of_device_id of_pmic_wdt_match[] = {
        { .compatible = "st,stpmic1-wdt" },
        { },
};

MODULE_DEVICE_TABLE(of, of_pmic_wdt_match);

static struct platform_driver stpmic1_wdt_driver = {
        .probe = pmic_wdt_probe,
        .driver = {
                .name = "stpmic1-wdt",
                .of_match_table = of_pmic_wdt_match,
        },
};
module_platform_driver(stpmic1_wdt_driver);

MODULE_DESCRIPTION("Watchdog driver for STPMIC1 device");
MODULE_AUTHOR("Pascal Paillet <p.paillet@st.com>");
MODULE_LICENSE("GPL v2");