1 /* 2 * SMsC 37B787 Watchdog Timer driver for Linux 2.6.x.x 3 * 4 * Based on acquirewdt.c by Alan Cox <alan@lxorguk.ukuu.org.uk> 5 * and some other existing drivers 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 2003-2006 Sven Anders <anders@anduras.de> 17 * 18 * History: 19 * 2003 - Created version 1.0 for Linux 2.4.x. 20 * 2006 - Ported to Linux 2.6, added nowayout and MAGICCLOSE 21 * features. Released version 1.1 22 * 23 * Theory of operation: 24 * 25 * A Watchdog Timer (WDT) is a hardware circuit that can 26 * reset the computer system in case of a software fault. 27 * You probably knew that already. 28 * 29 * Usually a userspace daemon will notify the kernel WDT driver 30 * via the /dev/watchdog special device file that userspace is 31 * still alive, at regular intervals. When such a notification 32 * occurs, the driver will usually tell the hardware watchdog 33 * that everything is in order, and that the watchdog should wait 34 * for yet another little while to reset the system. 35 * If userspace fails (RAM error, kernel bug, whatever), the 36 * notifications cease to occur, and the hardware watchdog will 37 * reset the system (causing a reboot) after the timeout occurs. 38 * 39 * Create device with: 40 * mknod /dev/watchdog c 10 130 41 * 42 * For an example userspace keep-alive daemon, see: 43 * Documentation/watchdog/wdt.txt 44 */ 45 46 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 47 48 #include <linux/module.h> 49 #include <linux/moduleparam.h> 50 #include <linux/types.h> 51 #include <linux/miscdevice.h> 52 #include <linux/watchdog.h> 53 #include <linux/delay.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/spinlock.h> 60 #include <linux/io.h> 61 #include <linux/uaccess.h> 62 63 64 /* enable support for minutes as units? */ 65 /* (does not always work correctly, so disabled by default!) */ 66 #define SMSC_SUPPORT_MINUTES 67 #undef SMSC_SUPPORT_MINUTES 68 69 #define MAX_TIMEOUT 255 70 71 #define UNIT_SECOND 0 72 #define UNIT_MINUTE 1 73 74 #define VERSION "1.1" 75 76 #define IOPORT 0x3F0 77 #define IOPORT_SIZE 2 78 #define IODEV_NO 8 79 80 static int unit = UNIT_SECOND; /* timer's unit */ 81 static int timeout = 60; /* timeout value: default is 60 "units" */ 82 static unsigned long timer_enabled; /* is the timer enabled? */ 83 84 static char expect_close; /* is the close expected? */ 85 86 static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */ 87 88 static bool nowayout = WATCHDOG_NOWAYOUT; 89 90 /* -- Low level function ----------------------------------------*/ 91 92 /* unlock the IO chip */ 93 94 static inline void open_io_config(void) 95 { 96 outb(0x55, IOPORT); 97 mdelay(1); 98 outb(0x55, IOPORT); 99 } 100 101 /* lock the IO chip */ 102 static inline void close_io_config(void) 103 { 104 outb(0xAA, IOPORT); 105 } 106 107 /* select the IO device */ 108 static inline void select_io_device(unsigned char devno) 109 { 110 outb(0x07, IOPORT); 111 outb(devno, IOPORT+1); 112 } 113 114 /* write to the control register */ 115 static inline void write_io_cr(unsigned char reg, unsigned char data) 116 { 117 outb(reg, IOPORT); 118 outb(data, IOPORT+1); 119 } 120 121 /* read from the control register */ 122 static inline char read_io_cr(unsigned char reg) 123 { 124 outb(reg, IOPORT); 125 return inb(IOPORT+1); 126 } 127 128 /* -- Medium level functions ------------------------------------*/ 129 130 static inline void gpio_bit12(unsigned char reg) 131 { 132 /* -- General Purpose I/O Bit 1.2 -- 133 * Bit 0, In/Out: 0 = Output, 1 = Input 134 * Bit 1, Polarity: 0 = No Invert, 1 = Invert 135 * Bit 2, Group Enable Intr.: 0 = Disable, 1 = Enable 136 * Bit 3/4, Function select: 00 = GPI/O, 01 = WDT, 10 = P17, 137 * 11 = Either Edge Triggered Intr. 2 138 * Bit 5/6 (Reserved) 139 * Bit 7, Output Type: 0 = Push Pull Bit, 1 = Open Drain 140 */ 141 write_io_cr(0xE2, reg); 142 } 143 144 static inline void gpio_bit13(unsigned char reg) 145 { 146 /* -- General Purpose I/O Bit 1.3 -- 147 * Bit 0, In/Out: 0 = Output, 1 = Input 148 * Bit 1, Polarity: 0 = No Invert, 1 = Invert 149 * Bit 2, Group Enable Intr.: 0 = Disable, 1 = Enable 150 * Bit 3, Function select: 0 = GPI/O, 1 = LED 151 * Bit 4-6 (Reserved) 152 * Bit 7, Output Type: 0 = Push Pull Bit, 1 = Open Drain 153 */ 154 write_io_cr(0xE3, reg); 155 } 156 157 static inline void wdt_timer_units(unsigned char new_units) 158 { 159 /* -- Watchdog timer units -- 160 * Bit 0-6 (Reserved) 161 * Bit 7, WDT Time-out Value Units Select 162 * (0 = Minutes, 1 = Seconds) 163 */ 164 write_io_cr(0xF1, new_units); 165 } 166 167 static inline void wdt_timeout_value(unsigned char new_timeout) 168 { 169 /* -- Watchdog Timer Time-out Value -- 170 * Bit 0-7 Binary coded units (0=Disabled, 1..255) 171 */ 172 write_io_cr(0xF2, new_timeout); 173 } 174 175 static inline void wdt_timer_conf(unsigned char conf) 176 { 177 /* -- Watchdog timer configuration -- 178 * Bit 0 Joystick enable: 0* = No Reset, 1 = Reset WDT upon 179 * Gameport I/O 180 * Bit 1 Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr. 181 * Bit 2 Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr 182 * Bit 3 Reset the timer 183 * (Wrong in SMsC documentation? Given as: PowerLED Timout 184 * Enabled) 185 * Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled, 186 * 0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15) 187 */ 188 write_io_cr(0xF3, conf); 189 } 190 191 static inline void wdt_timer_ctrl(unsigned char reg) 192 { 193 /* -- Watchdog timer control -- 194 * Bit 0 Status Bit: 0 = Timer counting, 1 = Timeout occurred 195 * Bit 1 Power LED Toggle: 0 = Disable Toggle, 1 = Toggle at 1 Hz 196 * Bit 2 Force Timeout: 1 = Forces WD timeout event (self-cleaning) 197 * Bit 3 P20 Force Timeout enabled: 198 * 0 = P20 activity does not generate the WD timeout event 199 * 1 = P20 Allows rising edge of P20, from the keyboard 200 * controller, to force the WD timeout event. 201 * Bit 4 (Reserved) 202 * -- Soft power management -- 203 * Bit 5 Stop Counter: 1 = Stop software power down counter 204 * set via register 0xB8, (self-cleaning) 205 * (Upon read: 0 = Counter running, 1 = Counter stopped) 206 * Bit 6 Restart Counter: 1 = Restart software power down counter 207 * set via register 0xB8, (self-cleaning) 208 * Bit 7 SPOFF: 1 = Force software power down (self-cleaning) 209 */ 210 write_io_cr(0xF4, reg); 211 } 212 213 /* -- Higher level functions ------------------------------------*/ 214 215 /* initialize watchdog */ 216 217 static void wb_smsc_wdt_initialize(void) 218 { 219 unsigned char old; 220 221 spin_lock(&io_lock); 222 open_io_config(); 223 select_io_device(IODEV_NO); 224 225 /* enable the watchdog */ 226 gpio_bit13(0x08); /* Select pin 80 = LED not GPIO */ 227 gpio_bit12(0x0A); /* Set pin 79 = WDT not 228 GPIO/Output/Polarity=Invert */ 229 /* disable the timeout */ 230 wdt_timeout_value(0); 231 232 /* reset control register */ 233 wdt_timer_ctrl(0x00); 234 235 /* reset configuration register */ 236 wdt_timer_conf(0x00); 237 238 /* read old (timer units) register */ 239 old = read_io_cr(0xF1) & 0x7F; 240 if (unit == UNIT_SECOND) 241 old |= 0x80; /* set to seconds */ 242 243 /* set the watchdog timer units */ 244 wdt_timer_units(old); 245 246 close_io_config(); 247 spin_unlock(&io_lock); 248 } 249 250 /* shutdown the watchdog */ 251 252 static void wb_smsc_wdt_shutdown(void) 253 { 254 spin_lock(&io_lock); 255 open_io_config(); 256 select_io_device(IODEV_NO); 257 258 /* disable the watchdog */ 259 gpio_bit13(0x09); 260 gpio_bit12(0x09); 261 262 /* reset watchdog config register */ 263 wdt_timer_conf(0x00); 264 265 /* reset watchdog control register */ 266 wdt_timer_ctrl(0x00); 267 268 /* disable timeout */ 269 wdt_timeout_value(0x00); 270 271 close_io_config(); 272 spin_unlock(&io_lock); 273 } 274 275 /* set timeout => enable watchdog */ 276 277 static void wb_smsc_wdt_set_timeout(unsigned char new_timeout) 278 { 279 spin_lock(&io_lock); 280 open_io_config(); 281 select_io_device(IODEV_NO); 282 283 /* set Power LED to blink, if we enable the timeout */ 284 wdt_timer_ctrl((new_timeout == 0) ? 0x00 : 0x02); 285 286 /* set timeout value */ 287 wdt_timeout_value(new_timeout); 288 289 close_io_config(); 290 spin_unlock(&io_lock); 291 } 292 293 /* get timeout */ 294 295 static unsigned char wb_smsc_wdt_get_timeout(void) 296 { 297 unsigned char set_timeout; 298 299 spin_lock(&io_lock); 300 open_io_config(); 301 select_io_device(IODEV_NO); 302 set_timeout = read_io_cr(0xF2); 303 close_io_config(); 304 spin_unlock(&io_lock); 305 306 return set_timeout; 307 } 308 309 /* disable watchdog */ 310 311 static void wb_smsc_wdt_disable(void) 312 { 313 /* set the timeout to 0 to disable the watchdog */ 314 wb_smsc_wdt_set_timeout(0); 315 } 316 317 /* enable watchdog by setting the current timeout */ 318 319 static void wb_smsc_wdt_enable(void) 320 { 321 /* set the current timeout... */ 322 wb_smsc_wdt_set_timeout(timeout); 323 } 324 325 /* reset the timer */ 326 327 static void wb_smsc_wdt_reset_timer(void) 328 { 329 spin_lock(&io_lock); 330 open_io_config(); 331 select_io_device(IODEV_NO); 332 333 /* reset the timer */ 334 wdt_timeout_value(timeout); 335 wdt_timer_conf(0x08); 336 337 close_io_config(); 338 spin_unlock(&io_lock); 339 } 340 341 /* return, if the watchdog is enabled (timeout is set...) */ 342 343 static int wb_smsc_wdt_status(void) 344 { 345 return (wb_smsc_wdt_get_timeout() == 0) ? 0 : WDIOF_KEEPALIVEPING; 346 } 347 348 349 /* -- File operations -------------------------------------------*/ 350 351 /* open => enable watchdog and set initial timeout */ 352 353 static int wb_smsc_wdt_open(struct inode *inode, struct file *file) 354 { 355 /* /dev/watchdog can only be opened once */ 356 357 if (test_and_set_bit(0, &timer_enabled)) 358 return -EBUSY; 359 360 if (nowayout) 361 __module_get(THIS_MODULE); 362 363 /* Reload and activate timer */ 364 wb_smsc_wdt_enable(); 365 366 pr_info("Watchdog enabled. Timeout set to %d %s\n", 367 timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)"); 368 369 return nonseekable_open(inode, file); 370 } 371 372 /* close => shut off the timer */ 373 374 static int wb_smsc_wdt_release(struct inode *inode, struct file *file) 375 { 376 /* Shut off the timer. */ 377 378 if (expect_close == 42) { 379 wb_smsc_wdt_disable(); 380 pr_info("Watchdog disabled, sleeping again...\n"); 381 } else { 382 pr_crit("Unexpected close, not stopping watchdog!\n"); 383 wb_smsc_wdt_reset_timer(); 384 } 385 386 clear_bit(0, &timer_enabled); 387 expect_close = 0; 388 return 0; 389 } 390 391 /* write => update the timer to keep the machine alive */ 392 393 static ssize_t wb_smsc_wdt_write(struct file *file, const char __user *data, 394 size_t len, loff_t *ppos) 395 { 396 /* See if we got the magic character 'V' and reload the timer */ 397 if (len) { 398 if (!nowayout) { 399 size_t i; 400 401 /* reset expect flag */ 402 expect_close = 0; 403 404 /* scan to see whether or not we got the 405 magic character */ 406 for (i = 0; i != len; i++) { 407 char c; 408 if (get_user(c, data + i)) 409 return -EFAULT; 410 if (c == 'V') 411 expect_close = 42; 412 } 413 } 414 415 /* someone wrote to us, we should reload the timer */ 416 wb_smsc_wdt_reset_timer(); 417 } 418 return len; 419 } 420 421 /* ioctl => control interface */ 422 423 static long wb_smsc_wdt_ioctl(struct file *file, 424 unsigned int cmd, unsigned long arg) 425 { 426 int new_timeout; 427 428 union { 429 struct watchdog_info __user *ident; 430 int __user *i; 431 } uarg; 432 433 static const struct watchdog_info ident = { 434 .options = WDIOF_KEEPALIVEPING | 435 WDIOF_SETTIMEOUT | 436 WDIOF_MAGICCLOSE, 437 .firmware_version = 0, 438 .identity = "SMsC 37B787 Watchdog", 439 }; 440 441 uarg.i = (int __user *)arg; 442 443 switch (cmd) { 444 case WDIOC_GETSUPPORT: 445 return copy_to_user(uarg.ident, &ident, sizeof(ident)) 446 ? -EFAULT : 0; 447 case WDIOC_GETSTATUS: 448 return put_user(wb_smsc_wdt_status(), uarg.i); 449 case WDIOC_GETBOOTSTATUS: 450 return put_user(0, uarg.i); 451 case WDIOC_SETOPTIONS: 452 { 453 int options, retval = -EINVAL; 454 455 if (get_user(options, uarg.i)) 456 return -EFAULT; 457 458 if (options & WDIOS_DISABLECARD) { 459 wb_smsc_wdt_disable(); 460 retval = 0; 461 } 462 if (options & WDIOS_ENABLECARD) { 463 wb_smsc_wdt_enable(); 464 retval = 0; 465 } 466 return retval; 467 } 468 case WDIOC_KEEPALIVE: 469 wb_smsc_wdt_reset_timer(); 470 return 0; 471 case WDIOC_SETTIMEOUT: 472 if (get_user(new_timeout, uarg.i)) 473 return -EFAULT; 474 /* the API states this is given in secs */ 475 if (unit == UNIT_MINUTE) 476 new_timeout /= 60; 477 if (new_timeout < 0 || new_timeout > MAX_TIMEOUT) 478 return -EINVAL; 479 timeout = new_timeout; 480 wb_smsc_wdt_set_timeout(timeout); 481 /* fall through and return the new timeout... */ 482 case WDIOC_GETTIMEOUT: 483 new_timeout = timeout; 484 if (unit == UNIT_MINUTE) 485 new_timeout *= 60; 486 return put_user(new_timeout, uarg.i); 487 default: 488 return -ENOTTY; 489 } 490 } 491 492 /* -- Notifier funtions -----------------------------------------*/ 493 494 static int wb_smsc_wdt_notify_sys(struct notifier_block *this, 495 unsigned long code, void *unused) 496 { 497 if (code == SYS_DOWN || code == SYS_HALT) { 498 /* set timeout to 0, to avoid possible race-condition */ 499 timeout = 0; 500 wb_smsc_wdt_disable(); 501 } 502 return NOTIFY_DONE; 503 } 504 505 /* -- Module's structures ---------------------------------------*/ 506 507 static const struct file_operations wb_smsc_wdt_fops = { 508 .owner = THIS_MODULE, 509 .llseek = no_llseek, 510 .write = wb_smsc_wdt_write, 511 .unlocked_ioctl = wb_smsc_wdt_ioctl, 512 .open = wb_smsc_wdt_open, 513 .release = wb_smsc_wdt_release, 514 }; 515 516 static struct notifier_block wb_smsc_wdt_notifier = { 517 .notifier_call = wb_smsc_wdt_notify_sys, 518 }; 519 520 static struct miscdevice wb_smsc_wdt_miscdev = { 521 .minor = WATCHDOG_MINOR, 522 .name = "watchdog", 523 .fops = &wb_smsc_wdt_fops, 524 }; 525 526 /* -- Module init functions -------------------------------------*/ 527 528 /* module's "constructor" */ 529 530 static int __init wb_smsc_wdt_init(void) 531 { 532 int ret; 533 534 pr_info("SMsC 37B787 watchdog component driver " 535 VERSION " initialising...\n"); 536 537 if (!request_region(IOPORT, IOPORT_SIZE, "SMsC 37B787 watchdog")) { 538 pr_err("Unable to register IO port %#x\n", IOPORT); 539 ret = -EBUSY; 540 goto out_pnp; 541 } 542 543 /* set new maximum, if it's too big */ 544 if (timeout > MAX_TIMEOUT) 545 timeout = MAX_TIMEOUT; 546 547 /* init the watchdog timer */ 548 wb_smsc_wdt_initialize(); 549 550 ret = register_reboot_notifier(&wb_smsc_wdt_notifier); 551 if (ret) { 552 pr_err("Unable to register reboot notifier err = %d\n", ret); 553 goto out_io; 554 } 555 556 ret = misc_register(&wb_smsc_wdt_miscdev); 557 if (ret) { 558 pr_err("Unable to register miscdev on minor %d\n", 559 WATCHDOG_MINOR); 560 goto out_rbt; 561 } 562 563 /* output info */ 564 pr_info("Timeout set to %d %s\n", 565 timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)"); 566 pr_info("Watchdog initialized and sleeping (nowayout=%d)...\n", 567 nowayout); 568 out_clean: 569 return ret; 570 571 out_rbt: 572 unregister_reboot_notifier(&wb_smsc_wdt_notifier); 573 574 out_io: 575 release_region(IOPORT, IOPORT_SIZE); 576 577 out_pnp: 578 goto out_clean; 579 } 580 581 /* module's "destructor" */ 582 583 static void __exit wb_smsc_wdt_exit(void) 584 { 585 /* Stop the timer before we leave */ 586 if (!nowayout) { 587 wb_smsc_wdt_shutdown(); 588 pr_info("Watchdog disabled\n"); 589 } 590 591 misc_deregister(&wb_smsc_wdt_miscdev); 592 unregister_reboot_notifier(&wb_smsc_wdt_notifier); 593 release_region(IOPORT, IOPORT_SIZE); 594 595 pr_info("SMsC 37B787 watchdog component driver removed\n"); 596 } 597 598 module_init(wb_smsc_wdt_init); 599 module_exit(wb_smsc_wdt_exit); 600 601 MODULE_AUTHOR("Sven Anders <anders@anduras.de>"); 602 MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version " 603 VERSION ")"); 604 MODULE_LICENSE("GPL"); 605 606 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 607 608 #ifdef SMSC_SUPPORT_MINUTES 609 module_param(unit, int, 0); 610 MODULE_PARM_DESC(unit, 611 "set unit to use, 0=seconds or 1=minutes, default is 0"); 612 #endif 613 614 module_param(timeout, int, 0); 615 MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60"); 616 617 module_param(nowayout, bool, 0); 618 MODULE_PARM_DESC(nowayout, 619 "Watchdog cannot be stopped once started (default=" 620 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 621