1 /* 2 * W83877F Computer Watchdog Timer driver 3 * 4 * Based on acquirewdt.c by Alan Cox, 5 * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 * 12 * The authors do NOT admit liability nor provide warranty for 13 * any of this software. This material is provided "AS-IS" in 14 * the hope that it may be useful for others. 15 * 16 * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net> 17 * 18 * 4/19 - 2001 [Initial revision] 19 * 9/27 - 2001 Added spinlocking 20 * 4/12 - 2002 [rob@osinvestor.com] Eliminate extra comments 21 * Eliminate fop_read 22 * Eliminate extra spin_unlock 23 * Added KERN_* tags to printks 24 * add CONFIG_WATCHDOG_NOWAYOUT support 25 * fix possible wdt_is_open race 26 * changed watchdog_info to correctly reflect what 27 * the driver offers 28 * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, 29 * WDIOC_SETTIMEOUT, 30 * WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls 31 * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces 32 * added extra printk's for startup problems 33 * use module_param 34 * made timeout (the emulated heartbeat) a 35 * module_param 36 * made the keepalive ping an internal subroutine 37 * 38 * This WDT driver is different from most other Linux WDT 39 * drivers in that the driver will ping the watchdog by itself, 40 * because this particular WDT has a very short timeout (1.6 41 * seconds) and it would be insane to count on any userspace 42 * daemon always getting scheduled within that time frame. 43 */ 44 45 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 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 #include <linux/io.h> 60 #include <linux/uaccess.h> 61 62 #define OUR_NAME "w83877f_wdt" 63 64 #define ENABLE_W83877F_PORT 0x3F0 65 #define ENABLE_W83877F 0x87 66 #define DISABLE_W83877F 0xAA 67 #define WDT_PING 0x443 68 #define WDT_REGISTER 0x14 69 #define WDT_ENABLE 0x9C 70 #define WDT_DISABLE 0x8C 71 72 /* 73 * The W83877F seems to be fixed at 1.6s timeout (at least on the 74 * EMACS PC-104 board I'm using). If we reset the watchdog every 75 * ~250ms we should be safe. */ 76 77 #define WDT_INTERVAL (HZ/4+1) 78 79 /* 80 * We must not require too good response from the userspace daemon. 81 * Here we require the userspace daemon to send us a heartbeat 82 * char to /dev/watchdog every 30 seconds. 83 */ 84 85 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ 86 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */ 87 static int timeout = WATCHDOG_TIMEOUT; 88 module_param(timeout, int, 0); 89 MODULE_PARM_DESC(timeout, 90 "Watchdog timeout in seconds. (1<=timeout<=3600, default=" 91 __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); 92 93 94 static bool nowayout = WATCHDOG_NOWAYOUT; 95 module_param(nowayout, bool, 0); 96 MODULE_PARM_DESC(nowayout, 97 "Watchdog cannot be stopped once started (default=" 98 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 99 100 static void wdt_timer_ping(struct timer_list *); 101 static DEFINE_TIMER(timer, wdt_timer_ping); 102 static unsigned long next_heartbeat; 103 static unsigned long wdt_is_open; 104 static char wdt_expect_close; 105 static DEFINE_SPINLOCK(wdt_spinlock); 106 107 /* 108 * Whack the dog 109 */ 110 111 static void wdt_timer_ping(struct timer_list *unused) 112 { 113 /* If we got a heartbeat pulse within the WDT_US_INTERVAL 114 * we agree to ping the WDT 115 */ 116 if (time_before(jiffies, next_heartbeat)) { 117 /* Ping the WDT */ 118 spin_lock(&wdt_spinlock); 119 120 /* Ping the WDT by reading from WDT_PING */ 121 inb_p(WDT_PING); 122 123 /* Re-set the timer interval */ 124 mod_timer(&timer, jiffies + WDT_INTERVAL); 125 126 spin_unlock(&wdt_spinlock); 127 128 } else 129 pr_warn("Heartbeat lost! Will not ping the watchdog\n"); 130 } 131 132 /* 133 * Utility routines 134 */ 135 136 static void wdt_change(int writeval) 137 { 138 unsigned long flags; 139 spin_lock_irqsave(&wdt_spinlock, flags); 140 141 /* buy some time */ 142 inb_p(WDT_PING); 143 144 /* make W83877F available */ 145 outb_p(ENABLE_W83877F, ENABLE_W83877F_PORT); 146 outb_p(ENABLE_W83877F, ENABLE_W83877F_PORT); 147 148 /* enable watchdog */ 149 outb_p(WDT_REGISTER, ENABLE_W83877F_PORT); 150 outb_p(writeval, ENABLE_W83877F_PORT+1); 151 152 /* lock the W8387FF away */ 153 outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT); 154 155 spin_unlock_irqrestore(&wdt_spinlock, flags); 156 } 157 158 static void wdt_startup(void) 159 { 160 next_heartbeat = jiffies + (timeout * HZ); 161 162 /* Start the timer */ 163 mod_timer(&timer, jiffies + WDT_INTERVAL); 164 165 wdt_change(WDT_ENABLE); 166 167 pr_info("Watchdog timer is now enabled\n"); 168 } 169 170 static void wdt_turnoff(void) 171 { 172 /* Stop the timer */ 173 del_timer(&timer); 174 175 wdt_change(WDT_DISABLE); 176 177 pr_info("Watchdog timer is now disabled...\n"); 178 } 179 180 static void wdt_keepalive(void) 181 { 182 /* user land ping */ 183 next_heartbeat = jiffies + (timeout * HZ); 184 } 185 186 /* 187 * /dev/watchdog handling 188 */ 189 190 static ssize_t fop_write(struct file *file, const char __user *buf, 191 size_t count, loff_t *ppos) 192 { 193 /* See if we got the magic character 'V' and reload the timer */ 194 if (count) { 195 if (!nowayout) { 196 size_t ofs; 197 198 /* note: just in case someone wrote the magic 199 character five months ago... */ 200 wdt_expect_close = 0; 201 202 /* scan to see whether or not we got the 203 magic character */ 204 for (ofs = 0; ofs != count; ofs++) { 205 char c; 206 if (get_user(c, buf + ofs)) 207 return -EFAULT; 208 if (c == 'V') 209 wdt_expect_close = 42; 210 } 211 } 212 213 /* someone wrote to us, we should restart timer */ 214 wdt_keepalive(); 215 } 216 return count; 217 } 218 219 static int fop_open(struct inode *inode, struct file *file) 220 { 221 /* Just in case we're already talking to someone... */ 222 if (test_and_set_bit(0, &wdt_is_open)) 223 return -EBUSY; 224 225 /* Good, fire up the show */ 226 wdt_startup(); 227 return nonseekable_open(inode, file); 228 } 229 230 static int fop_close(struct inode *inode, struct file *file) 231 { 232 if (wdt_expect_close == 42) 233 wdt_turnoff(); 234 else { 235 del_timer(&timer); 236 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n"); 237 } 238 clear_bit(0, &wdt_is_open); 239 wdt_expect_close = 0; 240 return 0; 241 } 242 243 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 244 { 245 void __user *argp = (void __user *)arg; 246 int __user *p = argp; 247 static const struct watchdog_info ident = { 248 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT 249 | WDIOF_MAGICCLOSE, 250 .firmware_version = 1, 251 .identity = "W83877F", 252 }; 253 254 switch (cmd) { 255 case WDIOC_GETSUPPORT: 256 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; 257 case WDIOC_GETSTATUS: 258 case WDIOC_GETBOOTSTATUS: 259 return put_user(0, p); 260 case WDIOC_SETOPTIONS: 261 { 262 int new_options, retval = -EINVAL; 263 264 if (get_user(new_options, p)) 265 return -EFAULT; 266 267 if (new_options & WDIOS_DISABLECARD) { 268 wdt_turnoff(); 269 retval = 0; 270 } 271 272 if (new_options & WDIOS_ENABLECARD) { 273 wdt_startup(); 274 retval = 0; 275 } 276 277 return retval; 278 } 279 case WDIOC_KEEPALIVE: 280 wdt_keepalive(); 281 return 0; 282 case WDIOC_SETTIMEOUT: 283 { 284 int new_timeout; 285 286 if (get_user(new_timeout, p)) 287 return -EFAULT; 288 289 /* arbitrary upper limit */ 290 if (new_timeout < 1 || new_timeout > 3600) 291 return -EINVAL; 292 293 timeout = new_timeout; 294 wdt_keepalive(); 295 } 296 /* Fall through */ 297 case WDIOC_GETTIMEOUT: 298 return put_user(timeout, p); 299 default: 300 return -ENOTTY; 301 } 302 } 303 304 static const struct file_operations wdt_fops = { 305 .owner = THIS_MODULE, 306 .llseek = no_llseek, 307 .write = fop_write, 308 .open = fop_open, 309 .release = fop_close, 310 .unlocked_ioctl = fop_ioctl, 311 }; 312 313 static struct miscdevice wdt_miscdev = { 314 .minor = WATCHDOG_MINOR, 315 .name = "watchdog", 316 .fops = &wdt_fops, 317 }; 318 319 /* 320 * Notifier for system down 321 */ 322 323 static int wdt_notify_sys(struct notifier_block *this, unsigned long code, 324 void *unused) 325 { 326 if (code == SYS_DOWN || code == SYS_HALT) 327 wdt_turnoff(); 328 return NOTIFY_DONE; 329 } 330 331 /* 332 * The WDT needs to learn about soft shutdowns in order to 333 * turn the timebomb registers off. 334 */ 335 336 static struct notifier_block wdt_notifier = { 337 .notifier_call = wdt_notify_sys, 338 }; 339 340 static void __exit w83877f_wdt_unload(void) 341 { 342 wdt_turnoff(); 343 344 /* Deregister */ 345 misc_deregister(&wdt_miscdev); 346 347 unregister_reboot_notifier(&wdt_notifier); 348 release_region(WDT_PING, 1); 349 release_region(ENABLE_W83877F_PORT, 2); 350 } 351 352 static int __init w83877f_wdt_init(void) 353 { 354 int rc = -EBUSY; 355 356 if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */ 357 timeout = WATCHDOG_TIMEOUT; 358 pr_info("timeout value must be 1 <= x <= 3600, using %d\n", 359 timeout); 360 } 361 362 if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) { 363 pr_err("I/O address 0x%04x already in use\n", 364 ENABLE_W83877F_PORT); 365 rc = -EIO; 366 goto err_out; 367 } 368 369 if (!request_region(WDT_PING, 1, "W8387FF WDT")) { 370 pr_err("I/O address 0x%04x already in use\n", WDT_PING); 371 rc = -EIO; 372 goto err_out_region1; 373 } 374 375 rc = register_reboot_notifier(&wdt_notifier); 376 if (rc) { 377 pr_err("cannot register reboot notifier (err=%d)\n", rc); 378 goto err_out_region2; 379 } 380 381 rc = misc_register(&wdt_miscdev); 382 if (rc) { 383 pr_err("cannot register miscdev on minor=%d (err=%d)\n", 384 wdt_miscdev.minor, rc); 385 goto err_out_reboot; 386 } 387 388 pr_info("WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n", 389 timeout, nowayout); 390 391 return 0; 392 393 err_out_reboot: 394 unregister_reboot_notifier(&wdt_notifier); 395 err_out_region2: 396 release_region(WDT_PING, 1); 397 err_out_region1: 398 release_region(ENABLE_W83877F_PORT, 2); 399 err_out: 400 return rc; 401 } 402 403 module_init(w83877f_wdt_init); 404 module_exit(w83877f_wdt_unload); 405 406 MODULE_AUTHOR("Scott and Bill Jennings"); 407 MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip"); 408 MODULE_LICENSE("GPL"); 409