// SPDX-License-Identifier: GPL-2.0-only
/*
 * Watchdog driver for Faraday Technology FTWDT010
 *
 * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
 *
 * Inspired by the out-of-tree drivers from OpenWRT:
 * Copyright (C) 2009 Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
 */

#include <linux/bitops.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/watchdog.h>

#define FTWDT010_WDCOUNTER      0x0
#define FTWDT010_WDLOAD         0x4
#define FTWDT010_WDRESTART      0x8
#define FTWDT010_WDCR           0xC

#define WDRESTART_MAGIC         0x5AB9

#define WDCR_CLOCK_5MHZ         BIT(4)
#define WDCR_WDEXT              BIT(3)
#define WDCR_WDINTR             BIT(2)
#define WDCR_SYS_RST            BIT(1)
#define WDCR_ENABLE             BIT(0)

#define WDT_CLOCK               5000000         /* 5 MHz */

struct ftwdt010_wdt {
        struct watchdog_device  wdd;
        struct device           *dev;
        void __iomem            *base;
        bool                    has_irq;
};

static inline
struct ftwdt010_wdt *to_ftwdt010_wdt(struct watchdog_device *wdd)
{
        return container_of(wdd, struct ftwdt010_wdt, wdd);
}

static void ftwdt010_enable(struct ftwdt010_wdt *gwdt,
                            unsigned int timeout,
                            bool need_irq)
{
        u32 enable;

        writel(timeout * WDT_CLOCK, gwdt->base + FTWDT010_WDLOAD);
        writel(WDRESTART_MAGIC, gwdt->base + FTWDT010_WDRESTART);
        /* set clock before enabling */
        enable = WDCR_CLOCK_5MHZ | WDCR_SYS_RST;
        writel(enable, gwdt->base + FTWDT010_WDCR);
        if (need_irq)
                enable |= WDCR_WDINTR;
        enable |= WDCR_ENABLE;
        writel(enable, gwdt->base + FTWDT010_WDCR);
}

static int ftwdt010_wdt_start(struct watchdog_device *wdd)
{
        struct ftwdt010_wdt *gwdt = to_ftwdt010_wdt(wdd);

        ftwdt010_enable(gwdt, wdd->timeout, gwdt->has_irq);
        return 0;
}

static int ftwdt010_wdt_stop(struct watchdog_device *wdd)
{
        struct ftwdt010_wdt *gwdt = to_ftwdt010_wdt(wdd);

        writel(0, gwdt->base + FTWDT010_WDCR);

        return 0;
}

static int ftwdt010_wdt_ping(struct watchdog_device *wdd)
{
        struct ftwdt010_wdt *gwdt = to_ftwdt010_wdt(wdd);

        writel(WDRESTART_MAGIC, gwdt->base + FTWDT010_WDRESTART);

        return 0;
}

static int ftwdt010_wdt_set_timeout(struct watchdog_device *wdd,
                                  unsigned int timeout)
{
        wdd->timeout = timeout;
        if (watchdog_active(wdd))
                ftwdt010_wdt_start(wdd);

        return 0;
}

static int ftwdt010_wdt_restart(struct watchdog_device *wdd,
                                unsigned long action, void *data)
{
        ftwdt010_enable(to_ftwdt010_wdt(wdd), 0, false);
        return 0;
}

static irqreturn_t ftwdt010_wdt_interrupt(int irq, void *data)
{
        struct ftwdt010_wdt *gwdt = data;

        watchdog_notify_pretimeout(&gwdt->wdd);

        return IRQ_HANDLED;
}

static const struct watchdog_ops ftwdt010_wdt_ops = {
        .start          = ftwdt010_wdt_start,
        .stop           = ftwdt010_wdt_stop,
        .ping           = ftwdt010_wdt_ping,
        .set_timeout    = ftwdt010_wdt_set_timeout,
        .restart        = ftwdt010_wdt_restart,
        .owner          = THIS_MODULE,
};

static const struct watchdog_info ftwdt010_wdt_info = {
        .options        = WDIOF_KEEPALIVEPING
                        | WDIOF_MAGICCLOSE
                        | WDIOF_SETTIMEOUT,
        .identity       = KBUILD_MODNAME,
};


static int ftwdt010_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct ftwdt010_wdt *gwdt;
        unsigned int reg;
        int irq;
        int ret;

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

        gwdt->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(gwdt->base))
                return PTR_ERR(gwdt->base);

        gwdt->dev = dev;
        gwdt->wdd.info = &ftwdt010_wdt_info;
        gwdt->wdd.ops = &ftwdt010_wdt_ops;
        gwdt->wdd.min_timeout = 1;
        gwdt->wdd.max_timeout = 0xFFFFFFFF / WDT_CLOCK;
        gwdt->wdd.parent = dev;

        /*
         * If 'timeout-sec' unspecified in devicetree, assume a 13 second
         * default.
         */
        gwdt->wdd.timeout = 13U;
        watchdog_init_timeout(&gwdt->wdd, 0, dev);

        reg = readw(gwdt->base + FTWDT010_WDCR);
        if (reg & WDCR_ENABLE) {
                /* Watchdog was enabled by the bootloader, disable it. */
                reg &= ~WDCR_ENABLE;
                writel(reg, gwdt->base + FTWDT010_WDCR);
        }

        irq = platform_get_irq(pdev, 0);
        if (irq > 0) {
                ret = devm_request_irq(dev, irq, ftwdt010_wdt_interrupt, 0,
                                       "watchdog bark", gwdt);
                if (ret)
                        return ret;
                gwdt->has_irq = true;
        }

        ret = devm_watchdog_register_device(dev, &gwdt->wdd);
        if (ret)
                return ret;

        /* Set up platform driver data */
        platform_set_drvdata(pdev, gwdt);
        dev_info(dev, "FTWDT010 watchdog driver enabled\n");

        return 0;
}

static int __maybe_unused ftwdt010_wdt_suspend(struct device *dev)
{
        struct ftwdt010_wdt *gwdt = dev_get_drvdata(dev);
        unsigned int reg;

        reg = readw(gwdt->base + FTWDT010_WDCR);
        reg &= ~WDCR_ENABLE;
        writel(reg, gwdt->base + FTWDT010_WDCR);

        return 0;
}

static int __maybe_unused ftwdt010_wdt_resume(struct device *dev)
{
        struct ftwdt010_wdt *gwdt = dev_get_drvdata(dev);
        unsigned int reg;

        if (watchdog_active(&gwdt->wdd)) {
                reg = readw(gwdt->base + FTWDT010_WDCR);
                reg |= WDCR_ENABLE;
                writel(reg, gwdt->base + FTWDT010_WDCR);
        }

        return 0;
}

static const struct dev_pm_ops ftwdt010_wdt_dev_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(ftwdt010_wdt_suspend,
                                ftwdt010_wdt_resume)
};

static const struct of_device_id ftwdt010_wdt_match[] = {
        { .compatible = "faraday,ftwdt010" },
        { .compatible = "cortina,gemini-watchdog" },
        {},
};
MODULE_DEVICE_TABLE(of, ftwdt010_wdt_match);

static struct platform_driver ftwdt010_wdt_driver = {
        .probe          = ftwdt010_wdt_probe,
        .driver         = {
                .name   = "ftwdt010-wdt",
                .of_match_table = ftwdt010_wdt_match,
                .pm = &ftwdt010_wdt_dev_pm_ops,
        },
};
module_platform_driver(ftwdt010_wdt_driver);
MODULE_AUTHOR("Linus Walleij");
MODULE_DESCRIPTION("Watchdog driver for Faraday Technology FTWDT010");
MODULE_LICENSE("GPL");