364 lines
7.5 KiB
C
364 lines
7.5 KiB
C
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/*
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* Xen Watchdog Driver
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*
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* (c) Copyright 2010 Novell, Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#define DRV_NAME "wdt"
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#define DRV_VERSION "0.01"
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#include <linux/bug.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/hrtimer.h>
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#include <linux/kernel.h>
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#include <linux/ktime.h>
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#include <linux/init.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/platform_device.h>
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#include <linux/spinlock.h>
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#include <linux/uaccess.h>
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#include <linux/watchdog.h>
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#include <xen/xen.h>
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#include <asm/xen/hypercall.h>
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#include <xen/interface/sched.h>
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static struct platform_device *platform_device;
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static DEFINE_SPINLOCK(wdt_lock);
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static struct sched_watchdog wdt;
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static __kernel_time_t wdt_expires;
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static bool is_active, expect_release;
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#define WATCHDOG_TIMEOUT 60 /* in seconds */
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static unsigned int timeout = WATCHDOG_TIMEOUT;
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module_param(timeout, uint, S_IRUGO);
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MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
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"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
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static bool nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, bool, S_IRUGO);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
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"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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static inline __kernel_time_t set_timeout(void)
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{
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wdt.timeout = timeout;
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return ktime_to_timespec(ktime_get()).tv_sec + timeout;
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}
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static int xen_wdt_start(void)
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{
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__kernel_time_t expires;
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int err;
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spin_lock(&wdt_lock);
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expires = set_timeout();
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if (!wdt.id)
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err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
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else
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err = -EBUSY;
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if (err > 0) {
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wdt.id = err;
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wdt_expires = expires;
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err = 0;
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} else
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BUG_ON(!err);
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spin_unlock(&wdt_lock);
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return err;
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}
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static int xen_wdt_stop(void)
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{
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int err = 0;
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spin_lock(&wdt_lock);
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wdt.timeout = 0;
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if (wdt.id)
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err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
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if (!err)
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wdt.id = 0;
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spin_unlock(&wdt_lock);
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return err;
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}
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static int xen_wdt_kick(void)
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{
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__kernel_time_t expires;
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int err;
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spin_lock(&wdt_lock);
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expires = set_timeout();
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if (wdt.id)
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err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
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else
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err = -ENXIO;
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if (!err)
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wdt_expires = expires;
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spin_unlock(&wdt_lock);
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return err;
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}
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static int xen_wdt_open(struct inode *inode, struct file *file)
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{
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int err;
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/* /dev/watchdog can only be opened once */
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if (xchg(&is_active, true))
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return -EBUSY;
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err = xen_wdt_start();
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if (err == -EBUSY)
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err = xen_wdt_kick();
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return err ?: nonseekable_open(inode, file);
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}
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static int xen_wdt_release(struct inode *inode, struct file *file)
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{
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int err = 0;
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if (expect_release)
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err = xen_wdt_stop();
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else {
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pr_crit("unexpected close, not stopping watchdog!\n");
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xen_wdt_kick();
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}
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is_active = err;
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expect_release = false;
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return err;
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}
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static ssize_t xen_wdt_write(struct file *file, const char __user *data,
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size_t len, loff_t *ppos)
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{
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/* See if we got the magic character 'V' and reload the timer */
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if (len) {
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if (!nowayout) {
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size_t i;
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/* in case it was set long ago */
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expect_release = false;
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/* scan to see whether or not we got the magic
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character */
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for (i = 0; i != len; i++) {
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char c;
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if (get_user(c, data + i))
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return -EFAULT;
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if (c == 'V')
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expect_release = true;
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}
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}
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/* someone wrote to us, we should reload the timer */
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xen_wdt_kick();
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}
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return len;
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}
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static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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int new_options, retval = -EINVAL;
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int new_timeout;
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int __user *argp = (void __user *)arg;
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static const struct watchdog_info ident = {
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.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
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.firmware_version = 0,
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.identity = DRV_NAME,
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};
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
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case WDIOC_GETSTATUS:
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case WDIOC_GETBOOTSTATUS:
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return put_user(0, argp);
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case WDIOC_SETOPTIONS:
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if (get_user(new_options, argp))
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return -EFAULT;
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if (new_options & WDIOS_DISABLECARD)
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retval = xen_wdt_stop();
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if (new_options & WDIOS_ENABLECARD) {
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retval = xen_wdt_start();
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if (retval == -EBUSY)
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retval = xen_wdt_kick();
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}
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return retval;
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case WDIOC_KEEPALIVE:
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xen_wdt_kick();
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return 0;
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case WDIOC_SETTIMEOUT:
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if (get_user(new_timeout, argp))
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return -EFAULT;
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if (!new_timeout)
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return -EINVAL;
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timeout = new_timeout;
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xen_wdt_kick();
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/* fall through */
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case WDIOC_GETTIMEOUT:
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return put_user(timeout, argp);
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case WDIOC_GETTIMELEFT:
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retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
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return put_user(retval, argp);
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}
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return -ENOTTY;
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}
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static const struct file_operations xen_wdt_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.write = xen_wdt_write,
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.unlocked_ioctl = xen_wdt_ioctl,
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.open = xen_wdt_open,
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.release = xen_wdt_release,
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};
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static struct miscdevice xen_wdt_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &xen_wdt_fops,
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};
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static int xen_wdt_probe(struct platform_device *dev)
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{
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struct sched_watchdog wd = { .id = ~0 };
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int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
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switch (ret) {
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case -EINVAL:
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if (!timeout) {
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timeout = WATCHDOG_TIMEOUT;
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pr_info("timeout value invalid, using %d\n", timeout);
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}
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ret = misc_register(&xen_wdt_miscdev);
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if (ret) {
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pr_err("cannot register miscdev on minor=%d (%d)\n",
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WATCHDOG_MINOR, ret);
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break;
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}
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pr_info("initialized (timeout=%ds, nowayout=%d)\n",
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timeout, nowayout);
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break;
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case -ENOSYS:
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pr_info("not supported\n");
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ret = -ENODEV;
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break;
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default:
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pr_info("bogus return value %d\n", ret);
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break;
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}
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return ret;
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}
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static int xen_wdt_remove(struct platform_device *dev)
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{
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/* Stop the timer before we leave */
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if (!nowayout)
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xen_wdt_stop();
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misc_deregister(&xen_wdt_miscdev);
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return 0;
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}
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static void xen_wdt_shutdown(struct platform_device *dev)
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{
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xen_wdt_stop();
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}
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static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
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{
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typeof(wdt.id) id = wdt.id;
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int rc = xen_wdt_stop();
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wdt.id = id;
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return rc;
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}
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static int xen_wdt_resume(struct platform_device *dev)
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{
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if (!wdt.id)
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return 0;
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wdt.id = 0;
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return xen_wdt_start();
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}
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static struct platform_driver xen_wdt_driver = {
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.probe = xen_wdt_probe,
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.remove = xen_wdt_remove,
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.shutdown = xen_wdt_shutdown,
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.suspend = xen_wdt_suspend,
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.resume = xen_wdt_resume,
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.driver = {
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.name = DRV_NAME,
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},
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};
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static int __init xen_wdt_init_module(void)
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{
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int err;
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if (!xen_domain())
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return -ENODEV;
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pr_info("Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
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err = platform_driver_register(&xen_wdt_driver);
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if (err)
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return err;
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platform_device = platform_device_register_simple(DRV_NAME,
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-1, NULL, 0);
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if (IS_ERR(platform_device)) {
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err = PTR_ERR(platform_device);
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platform_driver_unregister(&xen_wdt_driver);
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}
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return err;
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}
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static void __exit xen_wdt_cleanup_module(void)
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{
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platform_device_unregister(platform_device);
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platform_driver_unregister(&xen_wdt_driver);
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pr_info("module unloaded\n");
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}
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module_init(xen_wdt_init_module);
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module_exit(xen_wdt_cleanup_module);
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MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
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MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
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MODULE_VERSION(DRV_VERSION);
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MODULE_LICENSE("GPL");
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