1 /* 2 * 60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x 3 * 4 * Based on acquirewdt.c by Alan Cox. 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 * 11 * The author does NOT admit liability nor provide warranty for 12 * any of this software. This material is provided "AS-IS" in 13 * the hope that it may be useful for others. 14 * 15 * (c) Copyright 2000 Jakob Oestergaard <jakob@unthought.net> 16 * 17 * 12/4 - 2000 [Initial revision] 18 * 25/4 - 2000 Added /dev/watchdog support 19 * 09/5 - 2001 [smj@oro.net] fixed fop_write to "return 1" on success 20 * 12/4 - 2002 [rob@osinvestor.com] eliminate fop_read 21 * fix possible wdt_is_open race 22 * add CONFIG_WATCHDOG_NOWAYOUT support 23 * remove lock_kernel/unlock_kernel pairs 24 * added KERN_* to printk's 25 * got rid of extraneous comments 26 * changed watchdog_info to correctly reflect what the driver offers 27 * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, WDIOC_SETTIMEOUT, 28 * WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls 29 * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces 30 * use module_param 31 * made timeout (the emulated heartbeat) a module_param 32 * made the keepalive ping an internal subroutine 33 * made wdt_stop and wdt_start module params 34 * added extra printk's for startup problems 35 * added MODULE_AUTHOR and MODULE_DESCRIPTION info 36 * 37 * 38 * This WDT driver is different from the other Linux WDT 39 * drivers in the following ways: 40 * *) The driver will ping the watchdog by itself, because this 41 * particular WDT has a very short timeout (one second) and it 42 * would be insane to count on any userspace daemon always 43 * getting scheduled within that time frame. 44 * 45 */ 46 47 #include <linux/module.h> 48 #include <linux/moduleparam.h> 49 #include <linux/types.h> 50 #include <linux/timer.h> 51 #include <linux/jiffies.h> 52 #include <linux/miscdevice.h> 53 #include <linux/watchdog.h> 54 #include <linux/fs.h> 55 #include <linux/ioport.h> 56 #include <linux/notifier.h> 57 #include <linux/reboot.h> 58 #include <linux/init.h> 59 60 #include <asm/io.h> 61 #include <asm/uaccess.h> 62 #include <asm/system.h> 63 64 #define OUR_NAME "sbc60xxwdt" 65 #define PFX OUR_NAME ": " 66 67 /* 68 * You must set these - The driver cannot probe for the settings 69 */ 70 71 static int wdt_stop = 0x45; 72 module_param(wdt_stop, int, 0); 73 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)"); 74 75 static int wdt_start = 0x443; 76 module_param(wdt_start, int, 0); 77 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)"); 78 79 /* 80 * The 60xx board can use watchdog timeout values from one second 81 * to several minutes. The default is one second, so if we reset 82 * the watchdog every ~250ms we should be safe. 83 */ 84 85 #define WDT_INTERVAL (HZ/4+1) 86 87 /* 88 * We must not require too good response from the userspace daemon. 89 * Here we require the userspace daemon to send us a heartbeat 90 * char to /dev/watchdog every 30 seconds. 91 * If the daemon pulses us every 25 seconds, we can still afford 92 * a 5 second scheduling delay on the (high priority) daemon. That 93 * should be sufficient for a box under any load. 94 */ 95 96 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ 97 static int timeout = WATCHDOG_TIMEOUT; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */ 98 module_param(timeout, int, 0); 99 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); 100 101 static int nowayout = WATCHDOG_NOWAYOUT; 102 module_param(nowayout, int, 0); 103 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 104 105 static void wdt_timer_ping(unsigned long); 106 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0); 107 static unsigned long next_heartbeat; 108 static unsigned long wdt_is_open; 109 static char wdt_expect_close; 110 111 /* 112 * Whack the dog 113 */ 114 115 static void wdt_timer_ping(unsigned long data) 116 { 117 /* If we got a heartbeat pulse within the WDT_US_INTERVAL 118 * we agree to ping the WDT 119 */ 120 if(time_before(jiffies, next_heartbeat)) 121 { 122 /* Ping the WDT by reading from wdt_start */ 123 inb_p(wdt_start); 124 /* Re-set the timer interval */ 125 mod_timer(&timer, jiffies + WDT_INTERVAL); 126 } else { 127 printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n"); 128 } 129 } 130 131 /* 132 * Utility routines 133 */ 134 135 static void wdt_startup(void) 136 { 137 next_heartbeat = jiffies + (timeout * HZ); 138 139 /* Start the timer */ 140 mod_timer(&timer, jiffies + WDT_INTERVAL); 141 printk(KERN_INFO PFX "Watchdog timer is now enabled.\n"); 142 } 143 144 static void wdt_turnoff(void) 145 { 146 /* Stop the timer */ 147 del_timer(&timer); 148 inb_p(wdt_stop); 149 printk(KERN_INFO PFX "Watchdog timer is now disabled...\n"); 150 } 151 152 static void wdt_keepalive(void) 153 { 154 /* user land ping */ 155 next_heartbeat = jiffies + (timeout * HZ); 156 } 157 158 /* 159 * /dev/watchdog handling 160 */ 161 162 static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos) 163 { 164 /* See if we got the magic character 'V' and reload the timer */ 165 if(count) 166 { 167 if (!nowayout) 168 { 169 size_t ofs; 170 171 /* note: just in case someone wrote the magic character 172 * five months ago... */ 173 wdt_expect_close = 0; 174 175 /* scan to see whether or not we got the magic character */ 176 for(ofs = 0; ofs != count; ofs++) 177 { 178 char c; 179 if(get_user(c, buf+ofs)) 180 return -EFAULT; 181 if(c == 'V') 182 wdt_expect_close = 42; 183 } 184 } 185 186 /* Well, anyhow someone wrote to us, we should return that favour */ 187 wdt_keepalive(); 188 } 189 return count; 190 } 191 192 static int fop_open(struct inode * inode, struct file * file) 193 { 194 /* Just in case we're already talking to someone... */ 195 if(test_and_set_bit(0, &wdt_is_open)) 196 return -EBUSY; 197 198 if (nowayout) 199 __module_get(THIS_MODULE); 200 201 /* Good, fire up the show */ 202 wdt_startup(); 203 return nonseekable_open(inode, file); 204 } 205 206 static int fop_close(struct inode * inode, struct file * file) 207 { 208 if(wdt_expect_close == 42) 209 wdt_turnoff(); 210 else { 211 del_timer(&timer); 212 printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n"); 213 } 214 clear_bit(0, &wdt_is_open); 215 wdt_expect_close = 0; 216 return 0; 217 } 218 219 static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd, 220 unsigned long arg) 221 { 222 void __user *argp = (void __user *)arg; 223 int __user *p = argp; 224 static struct watchdog_info ident= 225 { 226 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, 227 .firmware_version = 1, 228 .identity = "SBC60xx", 229 }; 230 231 switch(cmd) 232 { 233 default: 234 return -ENOTTY; 235 case WDIOC_GETSUPPORT: 236 return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0; 237 case WDIOC_GETSTATUS: 238 case WDIOC_GETBOOTSTATUS: 239 return put_user(0, p); 240 case WDIOC_KEEPALIVE: 241 wdt_keepalive(); 242 return 0; 243 case WDIOC_SETOPTIONS: 244 { 245 int new_options, retval = -EINVAL; 246 247 if(get_user(new_options, p)) 248 return -EFAULT; 249 250 if(new_options & WDIOS_DISABLECARD) { 251 wdt_turnoff(); 252 retval = 0; 253 } 254 255 if(new_options & WDIOS_ENABLECARD) { 256 wdt_startup(); 257 retval = 0; 258 } 259 260 return retval; 261 } 262 case WDIOC_SETTIMEOUT: 263 { 264 int new_timeout; 265 266 if(get_user(new_timeout, p)) 267 return -EFAULT; 268 269 if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */ 270 return -EINVAL; 271 272 timeout = new_timeout; 273 wdt_keepalive(); 274 /* Fall through */ 275 } 276 case WDIOC_GETTIMEOUT: 277 return put_user(timeout, p); 278 } 279 } 280 281 static const struct file_operations wdt_fops = { 282 .owner = THIS_MODULE, 283 .llseek = no_llseek, 284 .write = fop_write, 285 .open = fop_open, 286 .release = fop_close, 287 .ioctl = fop_ioctl, 288 }; 289 290 static struct miscdevice wdt_miscdev = { 291 .minor = WATCHDOG_MINOR, 292 .name = "watchdog", 293 .fops = &wdt_fops, 294 }; 295 296 /* 297 * Notifier for system down 298 */ 299 300 static int wdt_notify_sys(struct notifier_block *this, unsigned long code, 301 void *unused) 302 { 303 if(code==SYS_DOWN || code==SYS_HALT) 304 wdt_turnoff(); 305 return NOTIFY_DONE; 306 } 307 308 /* 309 * The WDT needs to learn about soft shutdowns in order to 310 * turn the timebomb registers off. 311 */ 312 313 static struct notifier_block wdt_notifier= 314 { 315 .notifier_call = wdt_notify_sys, 316 }; 317 318 static void __exit sbc60xxwdt_unload(void) 319 { 320 wdt_turnoff(); 321 322 /* Deregister */ 323 misc_deregister(&wdt_miscdev); 324 325 unregister_reboot_notifier(&wdt_notifier); 326 if ((wdt_stop != 0x45) && (wdt_stop != wdt_start)) 327 release_region(wdt_stop,1); 328 release_region(wdt_start,1); 329 } 330 331 static int __init sbc60xxwdt_init(void) 332 { 333 int rc = -EBUSY; 334 335 if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */ 336 { 337 timeout = WATCHDOG_TIMEOUT; 338 printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n", 339 timeout); 340 } 341 342 if (!request_region(wdt_start, 1, "SBC 60XX WDT")) 343 { 344 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n", 345 wdt_start); 346 rc = -EIO; 347 goto err_out; 348 } 349 350 /* We cannot reserve 0x45 - the kernel already has! */ 351 if ((wdt_stop != 0x45) && (wdt_stop != wdt_start)) 352 { 353 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) 354 { 355 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n", 356 wdt_stop); 357 rc = -EIO; 358 goto err_out_region1; 359 } 360 } 361 362 rc = register_reboot_notifier(&wdt_notifier); 363 if (rc) 364 { 365 printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", 366 rc); 367 goto err_out_region2; 368 } 369 370 rc = misc_register(&wdt_miscdev); 371 if (rc) 372 { 373 printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n", 374 wdt_miscdev.minor, rc); 375 goto err_out_reboot; 376 } 377 378 printk(KERN_INFO PFX "WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n", 379 timeout, nowayout); 380 381 return 0; 382 383 err_out_reboot: 384 unregister_reboot_notifier(&wdt_notifier); 385 err_out_region2: 386 if ((wdt_stop != 0x45) && (wdt_stop != wdt_start)) 387 release_region(wdt_stop,1); 388 err_out_region1: 389 release_region(wdt_start,1); 390 err_out: 391 return rc; 392 } 393 394 module_init(sbc60xxwdt_init); 395 module_exit(sbc60xxwdt_unload); 396 397 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>"); 398 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver"); 399 MODULE_LICENSE("GPL"); 400 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 401