// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      sunxi Watchdog Driver
 *
 *      Copyright (c) 2013 Carlo Caione
 *                    2012 Henrik Nordstrom
 *
 *      Based on xen_wdt.c
 *      (c) Copyright 2010 Novell, Inc.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#include <linux/watchdog.h>

#define WDT_MAX_TIMEOUT         16
#define WDT_MIN_TIMEOUT         1
#define WDT_TIMEOUT_MASK        0x0F

#define WDT_CTRL_RELOAD         ((1 << 0) | (0x0a57 << 1))

#define WDT_MODE_EN             (1 << 0)

#define DRV_NAME                "sunxi-wdt"
#define DRV_VERSION             "1.0"

static bool nowayout = WATCHDOG_NOWAYOUT;
static unsigned int timeout;

/*
 * This structure stores the register offsets for different variants
 * of Allwinner's watchdog hardware.
 */
struct sunxi_wdt_reg {
        u8 wdt_ctrl;
        u8 wdt_cfg;
        u8 wdt_mode;
        u8 wdt_timeout_shift;
        u8 wdt_reset_mask;
        u8 wdt_reset_val;
        u32 wdt_key_val;
};

struct sunxi_wdt_dev {
        struct watchdog_device wdt_dev;
        void __iomem *wdt_base;
        const struct sunxi_wdt_reg *wdt_regs;
};

/*
 * wdt_timeout_map maps the watchdog timer interval value in seconds to
 * the value of the register WDT_MODE at bits .wdt_timeout_shift ~ +3
 *
 * [timeout seconds] = register value
 *
 */

static const int wdt_timeout_map[] = {
        [1] = 0x1,  /* 1s  */
        [2] = 0x2,  /* 2s  */
        [3] = 0x3,  /* 3s  */
        [4] = 0x4,  /* 4s  */
        [5] = 0x5,  /* 5s  */
        [6] = 0x6,  /* 6s  */
        [8] = 0x7,  /* 8s  */
        [10] = 0x8, /* 10s */
        [12] = 0x9, /* 12s */
        [14] = 0xA, /* 14s */
        [16] = 0xB, /* 16s */
};


static int sunxi_wdt_restart(struct watchdog_device *wdt_dev,
                             unsigned long action, void *data)
{
        struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);
        void __iomem *wdt_base = sunxi_wdt->wdt_base;
        const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs;
        u32 val;

        /* Set system reset function */
        val = readl(wdt_base + regs->wdt_cfg);
        val &= ~(regs->wdt_reset_mask);
        val |= regs->wdt_reset_val;
        val |= regs->wdt_key_val;
        writel(val, wdt_base + regs->wdt_cfg);

        /* Set lowest timeout and enable watchdog */
        val = readl(wdt_base + regs->wdt_mode);
        val &= ~(WDT_TIMEOUT_MASK << regs->wdt_timeout_shift);
        val |= WDT_MODE_EN;
        val |= regs->wdt_key_val;
        writel(val, wdt_base + regs->wdt_mode);

        /*
         * Restart the watchdog. The default (and lowest) interval
         * value for the watchdog is 0.5s.
         */
        writel(WDT_CTRL_RELOAD, wdt_base + regs->wdt_ctrl);

        while (1) {
                mdelay(5);
                val = readl(wdt_base + regs->wdt_mode);
                val |= WDT_MODE_EN;
                val |= regs->wdt_key_val;
                writel(val, wdt_base + regs->wdt_mode);
        }
        return 0;
}

static int sunxi_wdt_ping(struct watchdog_device *wdt_dev)
{
        struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);
        void __iomem *wdt_base = sunxi_wdt->wdt_base;
        const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs;

        writel(WDT_CTRL_RELOAD, wdt_base + regs->wdt_ctrl);

        return 0;
}

static int sunxi_wdt_set_timeout(struct watchdog_device *wdt_dev,
                unsigned int timeout)
{
        struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);
        void __iomem *wdt_base = sunxi_wdt->wdt_base;
        const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs;
        u32 reg;

        if (wdt_timeout_map[timeout] == 0)
                timeout++;

        sunxi_wdt->wdt_dev.timeout = timeout;

        reg = readl(wdt_base + regs->wdt_mode);
        reg &= ~(WDT_TIMEOUT_MASK << regs->wdt_timeout_shift);
        reg |= wdt_timeout_map[timeout] << regs->wdt_timeout_shift;
        reg |= regs->wdt_key_val;
        writel(reg, wdt_base + regs->wdt_mode);

        sunxi_wdt_ping(wdt_dev);

        return 0;
}

static int sunxi_wdt_stop(struct watchdog_device *wdt_dev)
{
        struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);
        void __iomem *wdt_base = sunxi_wdt->wdt_base;
        const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs;

        writel(regs->wdt_key_val, wdt_base + regs->wdt_mode);

        return 0;
}

static int sunxi_wdt_start(struct watchdog_device *wdt_dev)
{
        u32 reg;
        struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);
        void __iomem *wdt_base = sunxi_wdt->wdt_base;
        const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs;
        int ret;

        ret = sunxi_wdt_set_timeout(&sunxi_wdt->wdt_dev,
                        sunxi_wdt->wdt_dev.timeout);
        if (ret < 0)
                return ret;

        /* Set system reset function */
        reg = readl(wdt_base + regs->wdt_cfg);
        reg &= ~(regs->wdt_reset_mask);
        reg |= regs->wdt_reset_val;
        reg |= regs->wdt_key_val;
        writel(reg, wdt_base + regs->wdt_cfg);

        /* Enable watchdog */
        reg = readl(wdt_base + regs->wdt_mode);
        reg |= WDT_MODE_EN;
        reg |= regs->wdt_key_val;
        writel(reg, wdt_base + regs->wdt_mode);

        return 0;
}

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

static const struct watchdog_ops sunxi_wdt_ops = {
        .owner          = THIS_MODULE,
        .start          = sunxi_wdt_start,
        .stop           = sunxi_wdt_stop,
        .ping           = sunxi_wdt_ping,
        .set_timeout    = sunxi_wdt_set_timeout,
        .restart        = sunxi_wdt_restart,
};

static const struct sunxi_wdt_reg sun4i_wdt_reg = {
        .wdt_ctrl = 0x00,
        .wdt_cfg = 0x04,
        .wdt_mode = 0x04,
        .wdt_timeout_shift = 3,
        .wdt_reset_mask = 0x02,
        .wdt_reset_val = 0x02,
};

static const struct sunxi_wdt_reg sun6i_wdt_reg = {
        .wdt_ctrl = 0x10,
        .wdt_cfg = 0x14,
        .wdt_mode = 0x18,
        .wdt_timeout_shift = 4,
        .wdt_reset_mask = 0x03,
        .wdt_reset_val = 0x01,
};

static const struct sunxi_wdt_reg sun20i_wdt_reg = {
        .wdt_ctrl = 0x10,
        .wdt_cfg = 0x14,
        .wdt_mode = 0x18,
        .wdt_timeout_shift = 4,
        .wdt_reset_mask = 0x03,
        .wdt_reset_val = 0x01,
        .wdt_key_val = 0x16aa0000,
};

static const struct sunxi_wdt_reg sun55i_wdt_reg = {
        .wdt_ctrl = 0x0c,
        .wdt_cfg = 0x10,
        .wdt_mode = 0x14,
        .wdt_timeout_shift = 4,
        .wdt_reset_mask = 0x03,
        .wdt_reset_val = 0x01,
        .wdt_key_val = 0x16aa0000,
};

static const struct of_device_id sunxi_wdt_dt_ids[] = {
        { .compatible = "allwinner,sun4i-a10-wdt", .data = &sun4i_wdt_reg },
        { .compatible = "allwinner,sun6i-a31-wdt", .data = &sun6i_wdt_reg },
        { .compatible = "allwinner,sun20i-d1-wdt", .data = &sun20i_wdt_reg },
        { .compatible = "allwinner,sun55i-a523-wdt", .data = &sun55i_wdt_reg },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, sunxi_wdt_dt_ids);

static int sunxi_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct sunxi_wdt_dev *sunxi_wdt;
        int err;

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

        sunxi_wdt->wdt_regs = of_device_get_match_data(dev);
        if (!sunxi_wdt->wdt_regs)
                return -ENODEV;

        sunxi_wdt->wdt_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(sunxi_wdt->wdt_base))
                return PTR_ERR(sunxi_wdt->wdt_base);

        sunxi_wdt->wdt_dev.info = &sunxi_wdt_info;
        sunxi_wdt->wdt_dev.ops = &sunxi_wdt_ops;
        sunxi_wdt->wdt_dev.timeout = WDT_MAX_TIMEOUT;
        sunxi_wdt->wdt_dev.max_timeout = WDT_MAX_TIMEOUT;
        sunxi_wdt->wdt_dev.min_timeout = WDT_MIN_TIMEOUT;
        sunxi_wdt->wdt_dev.parent = dev;

        watchdog_init_timeout(&sunxi_wdt->wdt_dev, timeout, dev);
        watchdog_set_nowayout(&sunxi_wdt->wdt_dev, nowayout);
        watchdog_set_restart_priority(&sunxi_wdt->wdt_dev, 128);

        watchdog_set_drvdata(&sunxi_wdt->wdt_dev, sunxi_wdt);

        sunxi_wdt_stop(&sunxi_wdt->wdt_dev);

        watchdog_stop_on_reboot(&sunxi_wdt->wdt_dev);
        err = devm_watchdog_register_device(dev, &sunxi_wdt->wdt_dev);
        if (unlikely(err))
                return err;

        dev_info(dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)",
                 sunxi_wdt->wdt_dev.timeout, nowayout);

        return 0;
}

static struct platform_driver sunxi_wdt_driver = {
        .probe          = sunxi_wdt_probe,
        .driver         = {
                .name           = DRV_NAME,
                .of_match_table = sunxi_wdt_dt_ids,
        },
};

module_platform_driver(sunxi_wdt_driver);

module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");

module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
                "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Carlo Caione <carlo.caione@gmail.com>");
MODULE_AUTHOR("Henrik Nordstrom <henrik@henriknordstrom.net>");
MODULE_DESCRIPTION("sunxi WatchDog Timer Driver");
MODULE_VERSION(DRV_VERSION);