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 <asm/uaccess.h> 49 #include "mconsole.h" 50 51 MODULE_LICENSE("GPL"); 52 53 static DEFINE_MUTEX(harddog_mutex); 54 static DEFINE_SPINLOCK(lock); 55 static int timer_alive; 56 static int harddog_in_fd = -1; 57 static int harddog_out_fd = -1; 58 59 /* 60 * Allow only one person to hold it open 61 */ 62 63 extern int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock); 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 nonseekable_open(inode, file); 89 err: 90 spin_unlock(&lock); 91 mutex_unlock(&harddog_mutex); 92 return err; 93 } 94 95 extern void stop_watchdog(int in_fd, int out_fd); 96 97 static int harddog_release(struct inode *inode, struct file *file) 98 { 99 /* 100 * Shut off the timer. 101 */ 102 103 spin_lock(&lock); 104 105 stop_watchdog(harddog_in_fd, harddog_out_fd); 106 harddog_in_fd = -1; 107 harddog_out_fd = -1; 108 109 timer_alive=0; 110 spin_unlock(&lock); 111 112 return 0; 113 } 114 115 extern int ping_watchdog(int fd); 116 117 static ssize_t harddog_write(struct file *file, const char __user *data, size_t len, 118 loff_t *ppos) 119 { 120 /* 121 * Refresh the timer. 122 */ 123 if(len) 124 return ping_watchdog(harddog_out_fd); 125 return 0; 126 } 127 128 static int harddog_ioctl_unlocked(struct file *file, 129 unsigned int cmd, unsigned long arg) 130 { 131 void __user *argp= (void __user *)arg; 132 static struct watchdog_info ident = { 133 WDIOC_SETTIMEOUT, 134 0, 135 "UML Hardware Watchdog" 136 }; 137 switch (cmd) { 138 default: 139 return -ENOTTY; 140 case WDIOC_GETSUPPORT: 141 if(copy_to_user(argp, &ident, sizeof(ident))) 142 return -EFAULT; 143 return 0; 144 case WDIOC_GETSTATUS: 145 case WDIOC_GETBOOTSTATUS: 146 return put_user(0,(int __user *)argp); 147 case WDIOC_KEEPALIVE: 148 return ping_watchdog(harddog_out_fd); 149 } 150 } 151 152 static long harddog_ioctl(struct file *file, 153 unsigned int cmd, unsigned long arg) 154 { 155 long ret; 156 157 mutex_lock(&harddog_mutex); 158 ret = harddog_ioctl_unlocked(file, cmd, arg); 159 mutex_unlock(&harddog_mutex); 160 161 return ret; 162 } 163 164 static const struct file_operations harddog_fops = { 165 .owner = THIS_MODULE, 166 .write = harddog_write, 167 .unlocked_ioctl = harddog_ioctl, 168 .open = harddog_open, 169 .release = harddog_release, 170 .llseek = no_llseek, 171 }; 172 173 static struct miscdevice harddog_miscdev = { 174 .minor = WATCHDOG_MINOR, 175 .name = "watchdog", 176 .fops = &harddog_fops, 177 }; 178 179 static char banner[] __initdata = KERN_INFO "UML Watchdog Timer\n"; 180 181 static int __init harddog_init(void) 182 { 183 int ret; 184 185 ret = misc_register(&harddog_miscdev); 186 187 if (ret) 188 return ret; 189 190 printk(banner); 191 192 return 0; 193 } 194 195 static void __exit harddog_exit(void) 196 { 197 misc_deregister(&harddog_miscdev); 198 } 199 200 module_init(harddog_init); 201 module_exit(harddog_exit); 202