mpc8xxx_wdt.c

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/*
 * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface
 *
 * Authors: Dave Updegraff <[email protected]>
 *      Kumar Gala <[email protected]>
 *      Attribution: from 83xx_wst: Florian Schirmer <[email protected]>
 *              ..and from sc520_wdt
 * Copyright (c) 2008  MontaVista Software, Inc.
 *                     Anton Vorontsov <[email protected]>
 *
 * Note: it appears that you can only actually ENABLE or DISABLE the thing
 * once after POR. Once enabled, you cannot disable, and vice versa.
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/miscdevice.h>
#include <linux/of_platform.h>
#include <linux/module.h>
#include <linux/watchdog.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <sysdev/fsl_soc.h>

struct mpc8xxx_wdt {
    __be32 res0;
    __be32 swcrr; /* System watchdog control register */
#define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
#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;
};

static struct mpc8xxx_wdt __iomem *wd_base;
static int mpc8xxx_wdt_init_late(void);

static u16 timeout = 0xffff;
module_param(timeout, ushort, 0);
MODULE_PARM_DESC(timeout,
    "Watchdog timeout in ticks. (0<timeout<65536, default=65535)");

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) ")");

/*
 * We always prescale, but if someone really doesn't want to they can set this
 * to 0
 */
static int prescale = 1;
static unsigned int timeout_sec;

static unsigned long wdt_is_open;
static DEFINE_SPINLOCK(wdt_spinlock);

static void mpc8xxx_wdt_keepalive(void)
{
    /* Ping the WDT */
    spin_lock(&wdt_spinlock);
    out_be16(&wd_base->swsrr, 0x556c);
    out_be16(&wd_base->swsrr, 0xaa39);
    spin_unlock(&wdt_spinlock);
}

static void mpc8xxx_wdt_timer_ping(unsigned long arg);
static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);

static void mpc8xxx_wdt_timer_ping(unsigned long arg)
{
    mpc8xxx_wdt_keepalive();
    /* We're pinging it twice faster than needed, just to be sure. */
    mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
}

static void mpc8xxx_wdt_pr_warn(const char *msg)
{
    pr_crit("%s, expect the %s soon!\n", msg,
        reset ? "reset" : "machine check exception");
}

static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
                 size_t count, loff_t *ppos)
{
    if (count)
        mpc8xxx_wdt_keepalive();
    return count;
}

static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
{
    u32 tmp = SWCRR_SWEN;
    if (test_and_set_bit(0, &wdt_is_open))
        return -EBUSY;

    /* Once we start the watchdog we can't stop it */
    if (nowayout)
        __module_get(THIS_MODULE);

    /* Good, fire up the show */
    if (prescale)
        tmp |= SWCRR_SWPR;
    if (reset)
        tmp |= SWCRR_SWRI;

    tmp |= timeout << 16;

    out_be32(&wd_base->swcrr, tmp);

    del_timer_sync(&wdt_timer);

    return nonseekable_open(inode, file);
}

static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
{
    if (!nowayout)
        mpc8xxx_wdt_timer_ping(0);
    else
        mpc8xxx_wdt_pr_warn("watchdog closed");
    clear_bit(0, &wdt_is_open);
    return 0;
}

static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    static const struct watchdog_info ident = {
        .options = WDIOF_KEEPALIVEPING,
        .firmware_version = 1,
        .identity = "MPC8xxx",
    };

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
    case WDIOC_GETSTATUS:
    case WDIOC_GETBOOTSTATUS:
        return put_user(0, p);
    case WDIOC_KEEPALIVE:
        mpc8xxx_wdt_keepalive();
        return 0;
    case WDIOC_GETTIMEOUT:
        return put_user(timeout_sec, p);
    default:
        return -ENOTTY;
    }
}

static const struct file_operations mpc8xxx_wdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = mpc8xxx_wdt_write,
    .unlocked_ioctl = mpc8xxx_wdt_ioctl,
    .open       = mpc8xxx_wdt_open,
    .release    = mpc8xxx_wdt_release,
};

static struct miscdevice mpc8xxx_wdt_miscdev = {
    .minor  = WATCHDOG_MINOR,
    .name   = "watchdog",
    .fops   = &mpc8xxx_wdt_fops,
};

static const struct of_device_id mpc8xxx_wdt_match[];
static int __devinit mpc8xxx_wdt_probe(struct platform_device *ofdev)
{
    int ret;
    const struct of_device_id *match;
    struct device_node *np = ofdev->dev.of_node;
    const struct mpc8xxx_wdt_type *wdt_type;
    u32 freq = fsl_get_sys_freq();
    bool enabled;

    match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev);
    if (!match)
        return -EINVAL;
    wdt_type = match->data;

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

    wd_base = of_iomap(np, 0);
    if (!wd_base)
        return -ENOMEM;

    enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN;
    if (!enabled && wdt_type->hw_enabled) {
        pr_info("could not be enabled in software\n");
        ret = -ENOSYS;
        goto err_unmap;
    }

    /* Calculate the timeout in seconds */
    if (prescale)
        timeout_sec = (timeout * wdt_type->prescaler) / freq;
    else
        timeout_sec = timeout / freq;

#ifdef MODULE
    ret = mpc8xxx_wdt_init_late();
    if (ret)
        goto err_unmap;
#endif

    pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n",
        reset ? "reset" : "interrupt", timeout, timeout_sec);

    /*
     * 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_timer_ping(0);
    return 0;
err_unmap:
    iounmap(wd_base);
    wd_base = NULL;
    return ret;
}

static int __devexit mpc8xxx_wdt_remove(struct platform_device *ofdev)
{
    mpc8xxx_wdt_pr_warn("watchdog removed");
    del_timer_sync(&wdt_timer);
    misc_deregister(&mpc8xxx_wdt_miscdev);
    iounmap(wd_base);

    return 0;
}

static const struct of_device_id mpc8xxx_wdt_match[] = {
    {
        .compatible = "mpc83xx_wdt",
        .data = &(struct mpc8xxx_wdt_type) {
            .prescaler = 0x10000,
        },
    },
    {
        .compatible = "fsl,mpc8610-wdt",
        .data = &(struct mpc8xxx_wdt_type) {
            .prescaler = 0x10000,
            .hw_enabled = true,
        },
    },
    {
        .compatible = "fsl,mpc823-wdt",
        .data = &(struct mpc8xxx_wdt_type) {
            .prescaler = 0x800,
        },
    },
    {},
};
MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match);

static struct platform_driver mpc8xxx_wdt_driver = {
    .probe      = mpc8xxx_wdt_probe,
    .remove     = __devexit_p(mpc8xxx_wdt_remove),
    .driver = {
        .name = "mpc8xxx_wdt",
        .owner = THIS_MODULE,
        .of_match_table = mpc8xxx_wdt_match,
    },
};

/*
 * We do wdt initialization in two steps: arch_initcall probes the wdt
 * very early to start pinging the watchdog (misc devices are not yet
 * available), and later module_init() just registers the misc device.
 */
static int mpc8xxx_wdt_init_late(void)
{
    int ret;

    if (!wd_base)
        return -ENODEV;

    ret = misc_register(&mpc8xxx_wdt_miscdev);
    if (ret) {
        pr_err("cannot register miscdev on minor=%d (err=%d)\n",
               WATCHDOG_MINOR, ret);
        return ret;
    }
    return 0;
}
#ifndef MODULE
module_init(mpc8xxx_wdt_init_late);
#endif

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");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);