bcm63xx_wdt.c

Go to the documentation of this file.

/*
 *  Broadcom BCM63xx SoC watchdog driver
 *
 *  Copyright (C) 2007, Miguel Gaio <[email protected]>
 *  Copyright (C) 2008, Florian Fainelli <[email protected]>
 *
 *  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/bitops.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/watchdog.h>
#include <linux/timer.h>
#include <linux/jiffies.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>
#include <linux/resource.h>
#include <linux/platform_device.h>

#include <bcm63xx_cpu.h>
#include <bcm63xx_io.h>
#include <bcm63xx_regs.h>
#include <bcm63xx_timer.h>

#define PFX KBUILD_MODNAME

#define WDT_HZ      50000000 /* Fclk */
#define WDT_DEFAULT_TIME    30      /* seconds */
#define WDT_MAX_TIME        256     /* seconds */

static struct {
    void __iomem *regs;
    struct timer_list timer;
    int default_ticks;
    unsigned long inuse;
    atomic_t ticks;
} bcm63xx_wdt_device;

static int expect_close;

static int wdt_time = WDT_DEFAULT_TIME;
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) ")");

/* HW functions */
static void bcm63xx_wdt_hw_start(void)
{
    bcm_writel(0xfffffffe, bcm63xx_wdt_device.regs + WDT_DEFVAL_REG);
    bcm_writel(WDT_START_1, bcm63xx_wdt_device.regs + WDT_CTL_REG);
    bcm_writel(WDT_START_2, bcm63xx_wdt_device.regs + WDT_CTL_REG);
}

static void bcm63xx_wdt_hw_stop(void)
{
    bcm_writel(WDT_STOP_1, bcm63xx_wdt_device.regs + WDT_CTL_REG);
    bcm_writel(WDT_STOP_2, bcm63xx_wdt_device.regs + WDT_CTL_REG);
}

static void bcm63xx_wdt_isr(void *data)
{
    struct pt_regs *regs = get_irq_regs();

    die(PFX " fire", regs);
}

static void bcm63xx_timer_tick(unsigned long unused)
{
    if (!atomic_dec_and_test(&bcm63xx_wdt_device.ticks)) {
        bcm63xx_wdt_hw_start();
        mod_timer(&bcm63xx_wdt_device.timer, jiffies + HZ);
    } else
        pr_crit("watchdog will restart system\n");
}

static void bcm63xx_wdt_pet(void)
{
    atomic_set(&bcm63xx_wdt_device.ticks, wdt_time);
}

static void bcm63xx_wdt_start(void)
{
    bcm63xx_wdt_pet();
    bcm63xx_timer_tick(0);
}

static void bcm63xx_wdt_pause(void)
{
    del_timer_sync(&bcm63xx_wdt_device.timer);
    bcm63xx_wdt_hw_stop();
}

static int bcm63xx_wdt_settimeout(int new_time)
{
    if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
        return -EINVAL;

    wdt_time = new_time;

    return 0;
}

static int bcm63xx_wdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(0, &bcm63xx_wdt_device.inuse))
        return -EBUSY;

    bcm63xx_wdt_start();
    return nonseekable_open(inode, file);
}

static int bcm63xx_wdt_release(struct inode *inode, struct file *file)
{
    if (expect_close == 42)
        bcm63xx_wdt_pause();
    else {
        pr_crit("Unexpected close, not stopping watchdog!\n");
        bcm63xx_wdt_start();
    }
    clear_bit(0, &bcm63xx_wdt_device.inuse);
    expect_close = 0;
    return 0;
}

static ssize_t bcm63xx_wdt_write(struct file *file, const char *data,
                size_t len, loff_t *ppos)
{
    if (len) {
        if (!nowayout) {
            size_t i;

            /* In case it was set long ago */
            expect_close = 0;

            for (i = 0; i != len; i++) {
                char c;
                if (get_user(c, data + i))
                    return -EFAULT;
                if (c == 'V')
                    expect_close = 42;
            }
        }
        bcm63xx_wdt_pet();
    }
    return len;
}

static struct watchdog_info bcm63xx_wdt_info = {
    .identity       = PFX,
    .options        = WDIOF_SETTIMEOUT |
                WDIOF_KEEPALIVEPING |
                WDIOF_MAGICCLOSE,
};


static long bcm63xx_wdt_ioctl(struct file *file, unsigned int cmd,
                unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    int new_value, retval = -EINVAL;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        return copy_to_user(argp, &bcm63xx_wdt_info,
            sizeof(bcm63xx_wdt_info)) ? -EFAULT : 0;

    case WDIOC_GETSTATUS:
    case WDIOC_GETBOOTSTATUS:
        return put_user(0, p);

    case WDIOC_SETOPTIONS:
        if (get_user(new_value, p))
            return -EFAULT;

        if (new_value & WDIOS_DISABLECARD) {
            bcm63xx_wdt_pause();
            retval = 0;
        }
        if (new_value & WDIOS_ENABLECARD) {
            bcm63xx_wdt_start();
            retval = 0;
        }

        return retval;

    case WDIOC_KEEPALIVE:
        bcm63xx_wdt_pet();
        return 0;

    case WDIOC_SETTIMEOUT:
        if (get_user(new_value, p))
            return -EFAULT;

        if (bcm63xx_wdt_settimeout(new_value))
            return -EINVAL;

        bcm63xx_wdt_pet();

    case WDIOC_GETTIMEOUT:
        return put_user(wdt_time, p);

    default:
        return -ENOTTY;

    }
}

static const struct file_operations bcm63xx_wdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = bcm63xx_wdt_write,
    .unlocked_ioctl = bcm63xx_wdt_ioctl,
    .open       = bcm63xx_wdt_open,
    .release    = bcm63xx_wdt_release,
};

static struct miscdevice bcm63xx_wdt_miscdev = {
    .minor  = WATCHDOG_MINOR,
    .name   = "watchdog",
    .fops   = &bcm63xx_wdt_fops,
};


static int __devinit bcm63xx_wdt_probe(struct platform_device *pdev)
{
    int ret;
    struct resource *r;

    setup_timer(&bcm63xx_wdt_device.timer, bcm63xx_timer_tick, 0L);

    r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!r) {
        dev_err(&pdev->dev, "failed to get resources\n");
        return -ENODEV;
    }

    bcm63xx_wdt_device.regs = ioremap_nocache(r->start, resource_size(r));
    if (!bcm63xx_wdt_device.regs) {
        dev_err(&pdev->dev, "failed to remap I/O resources\n");
        return -ENXIO;
    }

    ret = bcm63xx_timer_register(TIMER_WDT_ID, bcm63xx_wdt_isr, NULL);
    if (ret < 0) {
        dev_err(&pdev->dev, "failed to register wdt timer isr\n");
        goto unmap;
    }

    if (bcm63xx_wdt_settimeout(wdt_time)) {
        bcm63xx_wdt_settimeout(WDT_DEFAULT_TIME);
        dev_info(&pdev->dev,
            ": wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
            wdt_time);
    }

    ret = misc_register(&bcm63xx_wdt_miscdev);
    if (ret < 0) {
        dev_err(&pdev->dev, "failed to register watchdog device\n");
        goto unregister_timer;
    }

    dev_info(&pdev->dev, " started, timer margin: %d sec\n",
                        WDT_DEFAULT_TIME);

    return 0;

unregister_timer:
    bcm63xx_timer_unregister(TIMER_WDT_ID);
unmap:
    iounmap(bcm63xx_wdt_device.regs);
    return ret;
}

static int __devexit bcm63xx_wdt_remove(struct platform_device *pdev)
{
    if (!nowayout)
        bcm63xx_wdt_pause();

    misc_deregister(&bcm63xx_wdt_miscdev);
    bcm63xx_timer_unregister(TIMER_WDT_ID);
    iounmap(bcm63xx_wdt_device.regs);
    return 0;
}

static void bcm63xx_wdt_shutdown(struct platform_device *pdev)
{
    bcm63xx_wdt_pause();
}

static struct platform_driver bcm63xx_wdt_driver = {
    .probe  = bcm63xx_wdt_probe,
    .remove = __devexit_p(bcm63xx_wdt_remove),
    .shutdown = bcm63xx_wdt_shutdown,
    .driver = {
        .owner = THIS_MODULE,
        .name = "bcm63xx-wdt",
    }
};

module_platform_driver(bcm63xx_wdt_driver);

MODULE_AUTHOR("Miguel Gaio <[email protected]>");
MODULE_AUTHOR("Florian Fainelli <[email protected]>");
MODULE_DESCRIPTION("Driver for the Broadcom BCM63xx SoC watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:bcm63xx-wdt");