1 /* UML hardware watchdog, shamelessly stolen from: 2 * 3 * SoftDog 0.05: A Software Watchdog Device 4 * 5 * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved. 6 * http://www.redhat.com 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License 10 * as published by the Free Software Foundation; either version 11 * 2 of the License, or (at your option) any later version. 12 * 13 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide 14 * warranty for any of this software. This material is provided 15 * "AS-IS" and at no charge. 16 * 17 * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk> 18 * 19 * Software only watchdog driver. Unlike its big brother the WDT501P 20 * driver this won't always recover a failed machine. 21 * 22 * 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> : 23 * Modularised. 24 * Added soft_margin; use upon insmod to change the timer delay. 25 * NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate 26 * minors. 27 * 28 * 19980911 Alan Cox 29 * Made SMP safe for 2.3.x 30 * 31 * 20011127 Joel Becker (jlbec@evilplan.org> 32 * Added soft_noboot; Allows testing the softdog trigger without 33 * requiring a recompile. 34 * Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT. 35 */ 36 37 #include <linux/module.h> 38 #include <linux/types.h> 39 #include <linux/kernel.h> 40 #include <linux/fs.h> 41 #include <linux/mm.h> 42 #include <linux/miscdevice.h> 43 #include <linux/watchdog.h> 44 #include <linux/reboot.h> 45 #include <linux/mutex.h> 46 #include <linux/init.h> 47 #include <linux/spinlock.h> 48 #include <linux/uaccess.h> 49 #include "mconsole.h" 50 #include "harddog.h" 51 52 MODULE_DESCRIPTION("UML hardware watchdog"); 53 MODULE_LICENSE("GPL"); 54 55 static DEFINE_MUTEX(harddog_mutex); 56 static DEFINE_SPINLOCK(lock); 57 static int timer_alive; 58 static int harddog_in_fd = -1; 59 static int harddog_out_fd = -1; 60 61 /* 62 * Allow only one person to hold it open 63 */ 64 65 static int harddog_open(struct inode *inode, struct file *file) 66 { 67 int err = -EBUSY; 68 char *sock = NULL; 69 70 mutex_lock(&harddog_mutex); 71 spin_lock(&lock); 72 if(timer_alive) 73 goto err; 74 #ifdef CONFIG_WATCHDOG_NOWAYOUT 75 __module_get(THIS_MODULE); 76 #endif 77 78 #ifdef CONFIG_MCONSOLE 79 sock = mconsole_notify_socket(); 80 #endif 81 err = start_watchdog(&harddog_in_fd, &harddog_out_fd, sock); 82 if(err) 83 goto err; 84 85 timer_alive = 1; 86 spin_unlock(&lock); 87 mutex_unlock(&harddog_mutex); 88 return stream_open(inode, file); 89 err: 90 spin_unlock(&lock); 91 mutex_unlock(&harddog_mutex); 92 return err; 93 } 94 95 static int harddog_release(struct inode *inode, struct file *file) 96 { 97 /* 98 * Shut off the timer. 99 */ 100 101 spin_lock(&lock); 102 103 stop_watchdog(harddog_in_fd, harddog_out_fd); 104 harddog_in_fd = -1; 105 harddog_out_fd = -1; 106 107 timer_alive=0; 108 spin_unlock(&lock); 109 110 return 0; 111 } 112 113 static ssize_t harddog_write(struct file *file, const char __user *data, size_t len, 114 loff_t *ppos) 115 { 116 /* 117 * Refresh the timer. 118 */ 119 if(len) 120 return ping_watchdog(harddog_out_fd); 121 return 0; 122 } 123 124 static int harddog_ioctl_unlocked(struct file *file, 125 unsigned int cmd, unsigned long arg) 126 { 127 void __user *argp= (void __user *)arg; 128 static struct watchdog_info ident = { 129 WDIOC_SETTIMEOUT, 130 0, 131 "UML Hardware Watchdog" 132 }; 133 switch (cmd) { 134 default: 135 return -ENOTTY; 136 case WDIOC_GETSUPPORT: 137 if(copy_to_user(argp, &ident, sizeof(ident))) 138 return -EFAULT; 139 return 0; 140 case WDIOC_GETSTATUS: 141 case WDIOC_GETBOOTSTATUS: 142 return put_user(0,(int __user *)argp); 143 case WDIOC_KEEPALIVE: 144 return ping_watchdog(harddog_out_fd); 145 } 146 } 147 148 static long harddog_ioctl(struct file *file, 149 unsigned int cmd, unsigned long arg) 150 { 151 long ret; 152 153 mutex_lock(&harddog_mutex); 154 ret = harddog_ioctl_unlocked(file, cmd, arg); 155 mutex_unlock(&harddog_mutex); 156 157 return ret; 158 } 159 160 static const struct file_operations harddog_fops = { 161 .owner = THIS_MODULE, 162 .write = harddog_write, 163 .unlocked_ioctl = harddog_ioctl, 164 .compat_ioctl = compat_ptr_ioctl, 165 .open = harddog_open, 166 .release = harddog_release, 167 .llseek = no_llseek, 168 }; 169 170 static struct miscdevice harddog_miscdev = { 171 .minor = WATCHDOG_MINOR, 172 .name = "watchdog", 173 .fops = &harddog_fops, 174 }; 175 module_misc_device(harddog_miscdev); 176