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/smp_lock.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_SPINLOCK(lock); 54 static int timer_alive; 55 static int harddog_in_fd = -1; 56 static int harddog_out_fd = -1; 57 58 /* 59 * Allow only one person to hold it open 60 */ 61 62 extern int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock); 63 64 static int harddog_open(struct inode *inode, struct file *file) 65 { 66 int err = -EBUSY; 67 char *sock = NULL; 68 69 lock_kernel(); 70 spin_lock(&lock); 71 if(timer_alive) 72 goto err; 73 #ifdef CONFIG_WATCHDOG_NOWAYOUT 74 __module_get(THIS_MODULE); 75 #endif 76 77 #ifdef CONFIG_MCONSOLE 78 sock = mconsole_notify_socket(); 79 #endif 80 err = start_watchdog(&harddog_in_fd, &harddog_out_fd, sock); 81 if(err) 82 goto err; 83 84 timer_alive = 1; 85 spin_unlock(&lock); 86 unlock_kernel(); 87 return nonseekable_open(inode, file); 88 err: 89 spin_unlock(&lock); 90 unlock_kernel(); 91 return err; 92 } 93 94 extern void stop_watchdog(int in_fd, int out_fd); 95 96 static int harddog_release(struct inode *inode, struct file *file) 97 { 98 /* 99 * Shut off the timer. 100 */ 101 102 spin_lock(&lock); 103 104 stop_watchdog(harddog_in_fd, harddog_out_fd); 105 harddog_in_fd = -1; 106 harddog_out_fd = -1; 107 108 timer_alive=0; 109 spin_unlock(&lock); 110 111 return 0; 112 } 113 114 extern int ping_watchdog(int fd); 115 116 static ssize_t harddog_write(struct file *file, const char __user *data, size_t len, 117 loff_t *ppos) 118 { 119 /* 120 * Refresh the timer. 121 */ 122 if(len) 123 return ping_watchdog(harddog_out_fd); 124 return 0; 125 } 126 127 static int harddog_ioctl_unlocked(struct file *file, 128 unsigned int cmd, unsigned long arg) 129 { 130 void __user *argp= (void __user *)arg; 131 static struct watchdog_info ident = { 132 WDIOC_SETTIMEOUT, 133 0, 134 "UML Hardware Watchdog" 135 }; 136 switch (cmd) { 137 default: 138 return -ENOTTY; 139 case WDIOC_GETSUPPORT: 140 if(copy_to_user(argp, &ident, sizeof(ident))) 141 return -EFAULT; 142 return 0; 143 case WDIOC_GETSTATUS: 144 case WDIOC_GETBOOTSTATUS: 145 return put_user(0,(int __user *)argp); 146 case WDIOC_KEEPALIVE: 147 return ping_watchdog(harddog_out_fd); 148 } 149 } 150 151 static long harddog_ioctl(struct file *file, 152 unsigned int cmd, unsigned long arg) 153 { 154 long ret; 155 156 lock_kernel(); 157 ret = harddog_ioctl_unlocked(file, cmd, arg); 158 unlock_kernel(); 159 160 return ret; 161 } 162 163 static const struct file_operations harddog_fops = { 164 .owner = THIS_MODULE, 165 .write = harddog_write, 166 .unlocked_ioctl = harddog_ioctl, 167 .open = harddog_open, 168 .release = harddog_release, 169 }; 170 171 static struct miscdevice harddog_miscdev = { 172 .minor = WATCHDOG_MINOR, 173 .name = "watchdog", 174 .fops = &harddog_fops, 175 }; 176 177 static char banner[] __initdata = KERN_INFO "UML Watchdog Timer\n"; 178 179 static int __init harddog_init(void) 180 { 181 int ret; 182 183 ret = misc_register(&harddog_miscdev); 184 185 if (ret) 186 return ret; 187 188 printk(banner); 189 190 return 0; 191 } 192 193 static void __exit harddog_exit(void) 194 { 195 misc_deregister(&harddog_miscdev); 196 } 197 198 module_init(harddog_init); 199 module_exit(harddog_exit); 200