// SPDX-License-Identifier: GPL-2.0
/*
 * Watchdog driver for the UniPhier watchdog timer
 *
 * (c) Copyright 2014 Panasonic Corporation
 * (c) Copyright 2016 Socionext Inc.
 * All rights reserved.
 */

#include <linux/bitops.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/watchdog.h>

/* WDT timer setting register */
#define WDTTIMSET                       0x3004
#define   WDTTIMSET_PERIOD_MASK         (0xf << 0)
#define   WDTTIMSET_PERIOD_1_SEC        (0x3 << 0)

/* WDT reset selection register */
#define WDTRSTSEL                       0x3008
#define   WDTRSTSEL_RSTSEL_MASK         (0x3 << 0)
#define   WDTRSTSEL_RSTSEL_BOTH         (0x0 << 0)
#define   WDTRSTSEL_RSTSEL_IRQ_ONLY     (0x2 << 0)

/* WDT control register */
#define WDTCTRL                         0x300c
#define   WDTCTRL_STATUS                BIT(8)
#define   WDTCTRL_CLEAR                 BIT(1)
#define   WDTCTRL_ENABLE                BIT(0)

#define SEC_TO_WDTTIMSET_PRD(sec) \
                (ilog2(sec) + WDTTIMSET_PERIOD_1_SEC)

#define WDTST_TIMEOUT                   1000 /* usec */

#define WDT_DEFAULT_TIMEOUT             64   /* Default is 64 seconds */
#define WDT_PERIOD_MIN                  1
#define WDT_PERIOD_MAX                  128

static unsigned int timeout = 0;
static bool nowayout = WATCHDOG_NOWAYOUT;

struct uniphier_wdt_dev {
        struct watchdog_device wdt_dev;
        struct regmap   *regmap;
};

/*
 * UniPhier Watchdog operations
 */
static int uniphier_watchdog_ping(struct watchdog_device *w)
{
        struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
        unsigned int val;
        int ret;

        /* Clear counter */
        ret = regmap_write_bits(wdev->regmap, WDTCTRL,
                                WDTCTRL_CLEAR, WDTCTRL_CLEAR);
        if (!ret)
                /*
                 * As SoC specification, after clear counter,
                 * it needs to wait until counter status is 1.
                 */
                ret = regmap_read_poll_timeout(wdev->regmap, WDTCTRL, val,
                                               (val & WDTCTRL_STATUS),
                                               0, WDTST_TIMEOUT);

        return ret;
}

static int __uniphier_watchdog_start(struct regmap *regmap, unsigned int sec)
{
        unsigned int val;
        int ret;

        ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,
                                       !(val & WDTCTRL_STATUS),
                                       0, WDTST_TIMEOUT);
        if (ret)
                return ret;

        /* Setup period */
        ret = regmap_write(regmap, WDTTIMSET,
                           SEC_TO_WDTTIMSET_PRD(sec));
        if (ret)
                return ret;

        /* Enable and clear watchdog */
        ret = regmap_write(regmap, WDTCTRL, WDTCTRL_ENABLE | WDTCTRL_CLEAR);
        if (!ret)
                /*
                 * As SoC specification, after clear counter,
                 * it needs to wait until counter status is 1.
                 */
                ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,
                                               (val & WDTCTRL_STATUS),
                                               0, WDTST_TIMEOUT);

        return ret;
}

static int __uniphier_watchdog_stop(struct regmap *regmap)
{
        /* Disable and stop watchdog */
        return regmap_write_bits(regmap, WDTCTRL, WDTCTRL_ENABLE, 0);
}

static int __uniphier_watchdog_restart(struct regmap *regmap, unsigned int sec)
{
        int ret;

        ret = __uniphier_watchdog_stop(regmap);
        if (ret)
                return ret;

        return __uniphier_watchdog_start(regmap, sec);
}

static int uniphier_watchdog_start(struct watchdog_device *w)
{
        struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
        unsigned int tmp_timeout;

        tmp_timeout = roundup_pow_of_two(w->timeout);

        return __uniphier_watchdog_start(wdev->regmap, tmp_timeout);
}

static int uniphier_watchdog_stop(struct watchdog_device *w)
{
        struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);

        return __uniphier_watchdog_stop(wdev->regmap);
}

static int uniphier_watchdog_set_timeout(struct watchdog_device *w,
                                         unsigned int t)
{
        struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
        unsigned int tmp_timeout;
        int ret;

        tmp_timeout = roundup_pow_of_two(t);
        if (tmp_timeout == w->timeout)
                return 0;

        if (watchdog_active(w)) {
                ret = __uniphier_watchdog_restart(wdev->regmap, tmp_timeout);
                if (ret)
                        return ret;
        }

        w->timeout = tmp_timeout;

        return 0;
}

/*
 * Kernel Interfaces
 */
static const struct watchdog_info uniphier_wdt_info = {
        .identity       = "uniphier-wdt",
        .options        = WDIOF_SETTIMEOUT |
                          WDIOF_KEEPALIVEPING |
                          WDIOF_MAGICCLOSE |
                          WDIOF_OVERHEAT,
};

static const struct watchdog_ops uniphier_wdt_ops = {
        .owner          = THIS_MODULE,
        .start          = uniphier_watchdog_start,
        .stop           = uniphier_watchdog_stop,
        .ping           = uniphier_watchdog_ping,
        .set_timeout    = uniphier_watchdog_set_timeout,
};

static int uniphier_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct uniphier_wdt_dev *wdev;
        struct regmap *regmap;
        struct device_node *parent;
        int ret;

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

        parent = of_get_parent(dev->of_node); /* parent should be syscon node */
        regmap = syscon_node_to_regmap(parent);
        of_node_put(parent);
        if (IS_ERR(regmap))
                return PTR_ERR(regmap);

        wdev->regmap = regmap;
        wdev->wdt_dev.info = &uniphier_wdt_info;
        wdev->wdt_dev.ops = &uniphier_wdt_ops;
        wdev->wdt_dev.max_timeout = WDT_PERIOD_MAX;
        wdev->wdt_dev.min_timeout = WDT_PERIOD_MIN;
        wdev->wdt_dev.timeout = WDT_DEFAULT_TIMEOUT;
        wdev->wdt_dev.parent = dev;

        watchdog_init_timeout(&wdev->wdt_dev, timeout, dev);
        watchdog_set_nowayout(&wdev->wdt_dev, nowayout);
        watchdog_stop_on_reboot(&wdev->wdt_dev);

        watchdog_set_drvdata(&wdev->wdt_dev, wdev);

        uniphier_watchdog_stop(&wdev->wdt_dev);
        ret = regmap_write(wdev->regmap, WDTRSTSEL, WDTRSTSEL_RSTSEL_BOTH);
        if (ret)
                return ret;

        ret = devm_watchdog_register_device(dev, &wdev->wdt_dev);
        if (ret)
                return ret;

        dev_info(dev, "watchdog driver (timeout=%d sec, nowayout=%d)\n",
                 wdev->wdt_dev.timeout, nowayout);

        return 0;
}

static const struct of_device_id uniphier_wdt_dt_ids[] = {
        { .compatible = "socionext,uniphier-wdt" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, uniphier_wdt_dt_ids);

static struct platform_driver uniphier_wdt_driver = {
        .probe          = uniphier_wdt_probe,
        .driver         = {
                .name           = "uniphier-wdt",
                .of_match_table = uniphier_wdt_dt_ids,
        },
};

module_platform_driver(uniphier_wdt_driver);

module_param(timeout, uint, 0000);
MODULE_PARM_DESC(timeout,
        "Watchdog timeout seconds in power of 2. (0 < timeout < 128, default="
                                __MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");

module_param(nowayout, bool, 0000);
MODULE_PARM_DESC(nowayout,
        "Watchdog cannot be stopped once started (default="
                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

MODULE_AUTHOR("Keiji Hayashibara <hayashibara.keiji@socionext.com>");
MODULE_DESCRIPTION("UniPhier Watchdog Device Driver");
MODULE_LICENSE("GPL v2");