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/config.h> 39 #include <linux/types.h> 40 #include <linux/kernel.h> 41 #include <linux/fs.h> 42 #include <linux/mm.h> 43 #include <linux/miscdevice.h> 44 #include <linux/watchdog.h> 45 #include <linux/reboot.h> 46 #include <linux/smp_lock.h> 47 #include <linux/init.h> 48 #include <asm/uaccess.h> 49 #include "helper.h" 50 #include "mconsole.h" 51 52 MODULE_LICENSE("GPL"); 53 54 /* Locked by the BKL in harddog_open and harddog_release */ 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; 68 char *sock = NULL; 69 70 lock_kernel(); 71 if(timer_alive) 72 return -EBUSY; 73 #ifdef CONFIG_HARDDOG_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) return(err); 82 83 timer_alive = 1; 84 unlock_kernel(); 85 return nonseekable_open(inode, file); 86 } 87 88 extern void stop_watchdog(int in_fd, int out_fd); 89 90 static int harddog_release(struct inode *inode, struct file *file) 91 { 92 /* 93 * Shut off the timer. 94 */ 95 lock_kernel(); 96 97 stop_watchdog(harddog_in_fd, harddog_out_fd); 98 harddog_in_fd = -1; 99 harddog_out_fd = -1; 100 101 timer_alive=0; 102 unlock_kernel(); 103 return 0; 104 } 105 106 extern int ping_watchdog(int fd); 107 108 static ssize_t harddog_write(struct file *file, const char *data, size_t len, 109 loff_t *ppos) 110 { 111 /* 112 * Refresh the timer. 113 */ 114 if(len) 115 return(ping_watchdog(harddog_out_fd)); 116 return 0; 117 } 118 119 static int harddog_ioctl(struct inode *inode, struct file *file, 120 unsigned int cmd, unsigned long arg) 121 { 122 static struct watchdog_info ident = { 123 WDIOC_SETTIMEOUT, 124 0, 125 "UML Hardware Watchdog" 126 }; 127 switch (cmd) { 128 default: 129 return -ENOTTY; 130 case WDIOC_GETSUPPORT: 131 if(copy_to_user((struct harddog_info *)arg, &ident, 132 sizeof(ident))) 133 return -EFAULT; 134 return 0; 135 case WDIOC_GETSTATUS: 136 case WDIOC_GETBOOTSTATUS: 137 return put_user(0,(int *)arg); 138 case WDIOC_KEEPALIVE: 139 return(ping_watchdog(harddog_out_fd)); 140 } 141 } 142 143 static struct file_operations harddog_fops = { 144 .owner = THIS_MODULE, 145 .write = harddog_write, 146 .ioctl = harddog_ioctl, 147 .open = harddog_open, 148 .release = harddog_release, 149 }; 150 151 static struct miscdevice harddog_miscdev = { 152 .minor = WATCHDOG_MINOR, 153 .name = "watchdog", 154 .fops = &harddog_fops, 155 }; 156 157 static char banner[] __initdata = KERN_INFO "UML Watchdog Timer\n"; 158 159 static int __init harddog_init(void) 160 { 161 int ret; 162 163 ret = misc_register(&harddog_miscdev); 164 165 if (ret) 166 return ret; 167 168 printk(banner); 169 170 return(0); 171 } 172 173 static void __exit harddog_exit(void) 174 { 175 misc_deregister(&harddog_miscdev); 176 } 177 178 module_init(harddog_init); 179 module_exit(harddog_exit); 180 181 /* 182 * Overrides for Emacs so that we follow Linus's tabbing style. 183 * Emacs will notice this stuff at the end of the file and automatically 184 * adjust the settings for this buffer only. This must remain at the end 185 * of the file. 186 * --------------------------------------------------------------------------- 187 * Local variables: 188 * c-file-style: "linux" 189 * End: 190 */ 191