| /* |
| * SoftDog 0.05: A Software Watchdog Device |
| * |
| * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved. |
| * http://www.redhat.com |
| * |
| * 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 Alan Cox nor CymruNet Ltd. admit liability nor provide |
| * warranty for any of this software. This material is provided |
| * "AS-IS" and at no charge. |
| * |
| * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk> |
| * |
| * Software only watchdog driver. Unlike its big brother the WDT501P |
| * driver this won't always recover a failed machine. |
| * |
| * 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> : |
| * Modularised. |
| * Added soft_margin; use upon insmod to change the timer delay. |
| * NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate |
| * minors. |
| * |
| * 19980911 Alan Cox |
| * Made SMP safe for 2.3.x |
| * |
| * 20011127 Joel Becker (jlbec@evilplan.org> |
| * Added soft_noboot; Allows testing the softdog trigger without |
| * requiring a recompile. |
| * Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT. |
| * |
| * 20020530 Joel Becker <joel.becker@oracle.com> |
| * Added Matt Domsch's nowayout module option. |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/config.h> |
| #include <linux/types.h> |
| #include <linux/kernel.h> |
| #include <linux/fs.h> |
| #include <linux/mm.h> |
| #include <linux/miscdevice.h> |
| #include <linux/watchdog.h> |
| #include <linux/reboot.h> |
| #include <linux/smp_lock.h> |
| #include <linux/init.h> |
| #include <asm/uaccess.h> |
| |
| #define TIMER_MARGIN 60 /* (secs) Default is 1 minute */ |
| |
| static int expect_close = 0; |
| static int soft_margin = TIMER_MARGIN; /* in seconds */ |
| #ifdef ONLY_TESTING |
| static int soft_noboot = 1; |
| #else |
| static int soft_noboot = 0; |
| #endif /* ONLY_TESTING */ |
| |
| MODULE_PARM(soft_margin,"i"); |
| MODULE_PARM(soft_noboot,"i"); |
| MODULE_LICENSE("GPL"); |
| |
| #ifdef CONFIG_WATCHDOG_NOWAYOUT |
| static int nowayout = 1; |
| #else |
| static int nowayout = 0; |
| #endif |
| |
| MODULE_PARM(nowayout,"i"); |
| MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)"); |
| |
| /* |
| * Our timer |
| */ |
| |
| static void watchdog_fire(unsigned long); |
| |
| static struct timer_list watchdog_ticktock = { |
| function: watchdog_fire, |
| }; |
| static unsigned long timer_alive; |
| |
| |
| /* |
| * If the timer expires.. |
| */ |
| |
| static void watchdog_fire(unsigned long data) |
| { |
| if (soft_noboot) |
| printk(KERN_CRIT "SOFTDOG: Triggered - Reboot ignored.\n"); |
| else |
| { |
| printk(KERN_CRIT "SOFTDOG: Initiating system reboot.\n"); |
| machine_restart(NULL); |
| printk("SOFTDOG: Reboot didn't ?????\n"); |
| } |
| } |
| |
| /* |
| * Allow only one person to hold it open |
| */ |
| |
| static int softdog_open(struct inode *inode, struct file *file) |
| { |
| if(test_and_set_bit(0, &timer_alive)) |
| return -EBUSY; |
| if (nowayout) { |
| MOD_INC_USE_COUNT; |
| } |
| /* |
| * Activate timer |
| */ |
| mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ)); |
| return 0; |
| } |
| |
| static int softdog_release(struct inode *inode, struct file *file) |
| { |
| /* |
| * Shut off the timer. |
| * Lock it in if it's a module and we set nowayout |
| */ |
| if (expect_close && nowayout == 0) { |
| del_timer(&watchdog_ticktock); |
| } else { |
| printk(KERN_CRIT "SOFTDOG: WDT device closed unexpectedly. WDT will not stop!\n"); |
| } |
| clear_bit(0, &timer_alive); |
| return 0; |
| } |
| |
| static ssize_t softdog_write(struct file *file, const char *data, size_t len, loff_t *ppos) |
| { |
| /* Can't seek (pwrite) on this device */ |
| if (ppos != &file->f_pos) |
| return -ESPIPE; |
| |
| /* |
| * Refresh the timer. |
| */ |
| 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 = 1; |
| } |
| } |
| mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ)); |
| return 1; |
| } |
| return 0; |
| } |
| |
| static int softdog_ioctl(struct inode *inode, struct file *file, |
| unsigned int cmd, unsigned long arg) |
| { |
| int new_margin; |
| static struct watchdog_info ident = { |
| WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, |
| 0, |
| "Software Watchdog" |
| }; |
| switch (cmd) { |
| default: |
| return -ENOTTY; |
| case WDIOC_GETSUPPORT: |
| if(copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident))) |
| return -EFAULT; |
| return 0; |
| case WDIOC_GETSTATUS: |
| case WDIOC_GETBOOTSTATUS: |
| return put_user(0,(int *)arg); |
| case WDIOC_KEEPALIVE: |
| mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ)); |
| return 0; |
| case WDIOC_SETTIMEOUT: |
| if (get_user(new_margin, (int *)arg)) |
| return -EFAULT; |
| if (new_margin < 1) |
| return -EINVAL; |
| soft_margin = new_margin; |
| mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ)); |
| /* Fall */ |
| case WDIOC_GETTIMEOUT: |
| return put_user(soft_margin, (int *)arg); |
| } |
| } |
| |
| static struct file_operations softdog_fops = { |
| owner: THIS_MODULE, |
| write: softdog_write, |
| ioctl: softdog_ioctl, |
| open: softdog_open, |
| release: softdog_release, |
| }; |
| |
| static struct miscdevice softdog_miscdev = { |
| minor: WATCHDOG_MINOR, |
| name: "watchdog", |
| fops: &softdog_fops, |
| }; |
| |
| static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.05, timer margin: %d sec\n"; |
| |
| static int __init watchdog_init(void) |
| { |
| int ret; |
| |
| ret = misc_register(&softdog_miscdev); |
| |
| if (ret) |
| return ret; |
| |
| printk(banner, soft_margin); |
| |
| return 0; |
| } |
| |
| static void __exit watchdog_exit(void) |
| { |
| misc_deregister(&softdog_miscdev); |
| } |
| |
| module_init(watchdog_init); |
| module_exit(watchdog_exit); |