// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface
 *
 * Authors: Dave Updegraff <dave@cray.org>
 *          Kumar Gala <galak@kernel.crashing.org>
 *              Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org>
 *                              ..and from sc520_wdt
 * Copyright (c) 2008  MontaVista Software, Inc.
 *                     Anton Vorontsov <avorontsov@ru.mvista.com>
 *
 * Note: it appears that you can only actually ENABLE or DISABLE the thing
 * once after POR. Once enabled, you cannot disable, and vice versa.
 */

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/watchdog.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <sysdev/fsl_soc.h>

#define WATCHDOG_TIMEOUT 10

struct mpc8xxx_wdt {
        __be32 res0;
        __be32 swcrr; /* System watchdog control register */
#define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
#define SWCRR_SWF  0x00000008 /* Software Watchdog Freeze (mpc8xx). */
#define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
#define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
#define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
        __be32 swcnr; /* System watchdog count register */
        u8 res1[2];
        __be16 swsrr; /* System watchdog service register */
        u8 res2[0xF0];
};

struct mpc8xxx_wdt_type {
        int prescaler;
        bool hw_enabled;
        u32 rsr_mask;
};

struct mpc8xxx_wdt_ddata {
        struct mpc8xxx_wdt __iomem *base;
        struct watchdog_device wdd;
        spinlock_t lock;
        u16 swtc;
};

static u16 timeout;
module_param(timeout, ushort, 0);
MODULE_PARM_DESC(timeout,
        "Watchdog timeout in seconds. (1<timeout<65535, default="
        __MODULE_STRING(WATCHDOG_TIMEOUT) ")");

static bool reset = 1;
module_param(reset, bool, 0);
MODULE_PARM_DESC(reset,
        "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");

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) ")");

static void mpc8xxx_wdt_keepalive(struct mpc8xxx_wdt_ddata *ddata)
{
        /* Ping the WDT */
        spin_lock(&ddata->lock);
        out_be16(&ddata->base->swsrr, 0x556c);
        out_be16(&ddata->base->swsrr, 0xaa39);
        spin_unlock(&ddata->lock);
}

static int mpc8xxx_wdt_start(struct watchdog_device *w)
{
        struct mpc8xxx_wdt_ddata *ddata =
                container_of(w, struct mpc8xxx_wdt_ddata, wdd);
        u32 tmp = in_be32(&ddata->base->swcrr);

        /* Good, fire up the show */
        tmp &= ~(SWCRR_SWTC | SWCRR_SWF | SWCRR_SWEN | SWCRR_SWRI | SWCRR_SWPR);
        tmp |= SWCRR_SWEN | SWCRR_SWPR | (ddata->swtc << 16);

        if (reset)
                tmp |= SWCRR_SWRI;

        out_be32(&ddata->base->swcrr, tmp);

        tmp = in_be32(&ddata->base->swcrr);
        if (!(tmp & SWCRR_SWEN))
                return -EOPNOTSUPP;

        ddata->swtc = tmp >> 16;
        set_bit(WDOG_HW_RUNNING, &ddata->wdd.status);

        mpc8xxx_wdt_keepalive(ddata);

        return 0;
}

static int mpc8xxx_wdt_ping(struct watchdog_device *w)
{
        struct mpc8xxx_wdt_ddata *ddata =
                container_of(w, struct mpc8xxx_wdt_ddata, wdd);

        mpc8xxx_wdt_keepalive(ddata);
        return 0;
}

static struct watchdog_info mpc8xxx_wdt_info = {
        .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT,
        .firmware_version = 1,
        .identity = "MPC8xxx",
};

static const struct watchdog_ops mpc8xxx_wdt_ops = {
        .owner = THIS_MODULE,
        .start = mpc8xxx_wdt_start,
        .ping = mpc8xxx_wdt_ping,
};

static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
{
        int ret;
        struct resource *res;
        const struct mpc8xxx_wdt_type *wdt_type;
        struct mpc8xxx_wdt_ddata *ddata;
        u32 freq = fsl_get_sys_freq();
        bool enabled;
        struct device *dev = &ofdev->dev;

        wdt_type = of_device_get_match_data(dev);
        if (!wdt_type)
                return -EINVAL;

        if (!freq || freq == -1)
                return -EINVAL;

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

        ddata->base = devm_platform_ioremap_resource(ofdev, 0);
        if (IS_ERR(ddata->base))
                return PTR_ERR(ddata->base);

        enabled = in_be32(&ddata->base->swcrr) & SWCRR_SWEN;
        if (!enabled && wdt_type->hw_enabled) {
                dev_info(dev, "could not be enabled in software\n");
                return -ENODEV;
        }

        res = platform_get_resource(ofdev, IORESOURCE_MEM, 1);
        if (res) {
                bool status;
                u32 __iomem *rsr = ioremap(res->start, resource_size(res));

                if (!rsr)
                        return -ENOMEM;

                status = in_be32(rsr) & wdt_type->rsr_mask;
                ddata->wdd.bootstatus = status ? WDIOF_CARDRESET : 0;
                 /* clear reset status bits related to watchdog timer */
                out_be32(rsr, wdt_type->rsr_mask);
                iounmap(rsr);

                dev_info(dev, "Last boot was %scaused by watchdog\n",
                         status ? "" : "not ");
        }

        spin_lock_init(&ddata->lock);

        ddata->wdd.info = &mpc8xxx_wdt_info;
        ddata->wdd.ops = &mpc8xxx_wdt_ops;

        ddata->wdd.timeout = WATCHDOG_TIMEOUT;
        watchdog_init_timeout(&ddata->wdd, timeout, dev);

        watchdog_set_nowayout(&ddata->wdd, nowayout);

        ddata->swtc = min(ddata->wdd.timeout * freq / wdt_type->prescaler,
                          0xffffU);

        /*
         * If the watchdog was previously enabled or we're running on
         * MPC8xxx, we should ping the wdt from the kernel until the
         * userspace handles it.
         */
        if (enabled)
                mpc8xxx_wdt_start(&ddata->wdd);

        ddata->wdd.max_hw_heartbeat_ms = (ddata->swtc * wdt_type->prescaler) /
                                         (freq / 1000);
        ddata->wdd.min_timeout = ddata->wdd.max_hw_heartbeat_ms / 1000;
        if (ddata->wdd.timeout < ddata->wdd.min_timeout)
                ddata->wdd.timeout = ddata->wdd.min_timeout;

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

        dev_info(dev,
                 "WDT driver for MPC8xxx initialized. mode:%s timeout=%d sec\n",
                 reset ? "reset" : "interrupt", ddata->wdd.timeout);

        platform_set_drvdata(ofdev, ddata);
        return 0;
}

static const struct of_device_id mpc8xxx_wdt_match[] = {
        {
                .compatible = "mpc83xx_wdt",
                .data = &(struct mpc8xxx_wdt_type) {
                        .prescaler = 0x10000,
                        .rsr_mask = BIT(3), /* RSR Bit SWRS */
                },
        },
        {
                .compatible = "fsl,mpc8610-wdt",
                .data = &(struct mpc8xxx_wdt_type) {
                        .prescaler = 0x10000,
                        .hw_enabled = true,
                        .rsr_mask = BIT(20), /* RSTRSCR Bit WDT_RR */
                },
        },
        {
                .compatible = "fsl,mpc823-wdt",
                .data = &(struct mpc8xxx_wdt_type) {
                        .prescaler = 0x800,
                        .hw_enabled = true,
                        .rsr_mask = BIT(28), /* RSR Bit SWRS */
                },
        },
        {},
};
MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);

static struct platform_driver mpc8xxx_wdt_driver = {
        .probe          = mpc8xxx_wdt_probe,
        .driver = {
                .name = "mpc8xxx_wdt",
                .of_match_table = mpc8xxx_wdt_match,
        },
};

static int __init mpc8xxx_wdt_init(void)
{
        return platform_driver_register(&mpc8xxx_wdt_driver);
}
arch_initcall(mpc8xxx_wdt_init);

static void __exit mpc8xxx_wdt_exit(void)
{
        platform_driver_unregister(&mpc8xxx_wdt_driver);
}
module_exit(mpc8xxx_wdt_exit);

MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx "
                   "uProcessors");
MODULE_LICENSE("GPL");