sa1100_wdt.c

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/*
 *  Watchdog driver for the SA11x0/PXA2xx
 *
 *  (c) Copyright 2000 Oleg Drokin <[email protected]>
 *      Based on SoftDog driver by Alan Cox <[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.
 *
 *  Neither Oleg Drokin nor iXcelerator.com admit liability nor provide
 *  warranty for any of this software. This material is provided
 *  "AS-IS" and at no charge.
 *
 *  (c) Copyright 2000           Oleg Drokin <[email protected]>
 *
 *  27/11/2000 Initial release
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/bitops.h>
#include <linux/uaccess.h>
#include <linux/timex.h>

#ifdef CONFIG_ARCH_PXA
#include <mach/regs-ost.h>
#endif

#include <mach/reset.h>
#include <mach/hardware.h>

static unsigned long oscr_freq;
static unsigned long sa1100wdt_users;
static unsigned int pre_margin;
static int boot_status;

/*
 *  Allow only one person to hold it open
 */
static int sa1100dog_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(1, &sa1100wdt_users))
        return -EBUSY;

    /* Activate SA1100 Watchdog timer */
    writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
    writel_relaxed(OSSR_M3, OSSR);
    writel_relaxed(OWER_WME, OWER);
    writel_relaxed(readl_relaxed(OIER) | OIER_E3, OIER);
    return nonseekable_open(inode, file);
}

/*
 * The watchdog cannot be disabled.
 *
 * Previous comments suggested that turning off the interrupt by
 * clearing OIER[E3] would prevent the watchdog timing out but this
 * does not appear to be true (at least on the PXA255).
 */
static int sa1100dog_release(struct inode *inode, struct file *file)
{
    pr_crit("Device closed - timer will not stop\n");
    clear_bit(1, &sa1100wdt_users);
    return 0;
}

static ssize_t sa1100dog_write(struct file *file, const char __user *data,
                        size_t len, loff_t *ppos)
{
    if (len)
        /* Refresh OSMR3 timer. */
        writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
    return len;
}

static const struct watchdog_info ident = {
    .options    = WDIOF_CARDRESET | WDIOF_SETTIMEOUT
                | WDIOF_KEEPALIVEPING,
    .identity   = "SA1100/PXA255 Watchdog",
    .firmware_version   = 1,
};

static long sa1100dog_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
    int ret = -ENOTTY;
    int time;
    void __user *argp = (void __user *)arg;
    int __user *p = argp;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        ret = copy_to_user(argp, &ident,
                   sizeof(ident)) ? -EFAULT : 0;
        break;

    case WDIOC_GETSTATUS:
        ret = put_user(0, p);
        break;

    case WDIOC_GETBOOTSTATUS:
        ret = put_user(boot_status, p);
        break;

    case WDIOC_KEEPALIVE:
        writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
        ret = 0;
        break;

    case WDIOC_SETTIMEOUT:
        ret = get_user(time, p);
        if (ret)
            break;

        if (time <= 0 || (oscr_freq * (long long)time >= 0xffffffff)) {
            ret = -EINVAL;
            break;
        }

        pre_margin = oscr_freq * time;
        writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
        /*fall through*/

    case WDIOC_GETTIMEOUT:
        ret = put_user(pre_margin / oscr_freq, p);
        break;
    }
    return ret;
}

static const struct file_operations sa1100dog_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = sa1100dog_write,
    .unlocked_ioctl = sa1100dog_ioctl,
    .open       = sa1100dog_open,
    .release    = sa1100dog_release,
};

static struct miscdevice sa1100dog_miscdev = {
    .minor      = WATCHDOG_MINOR,
    .name       = "watchdog",
    .fops       = &sa1100dog_fops,
};

static int margin __initdata = 60;      /* (secs) Default is 1 minute */

static int __init sa1100dog_init(void)
{
    int ret;

    oscr_freq = get_clock_tick_rate();

    /*
     * Read the reset status, and save it for later.  If
     * we suspend, RCSR will be cleared, and the watchdog
     * reset reason will be lost.
     */
    boot_status = (reset_status & RESET_STATUS_WATCHDOG) ?
                WDIOF_CARDRESET : 0;
    pre_margin = oscr_freq * margin;

    ret = misc_register(&sa1100dog_miscdev);
    if (ret == 0)
        pr_info("SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
            margin);
    return ret;
}

static void __exit sa1100dog_exit(void)
{
    misc_deregister(&sa1100dog_miscdev);
}

module_init(sa1100dog_init);
module_exit(sa1100dog_exit);

MODULE_AUTHOR("Oleg Drokin <[email protected]>");
MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");

module_param(margin, int, 0);
MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");

MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);