1/* 2 * SMsC 37B787 Watchdog Timer driver for Linux 2.6.x.x 3 * 4 * Based on acquirewdt.c by Alan Cox <alan@redhat.com> 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/watchdog.txt 44 */ 45 46#include <linux/module.h> 47#include <linux/moduleparam.h> 48#include <linux/types.h> 49#include <linux/miscdevice.h> 50#include <linux/watchdog.h> 51#include <linux/delay.h> 52#include <linux/fs.h> 53#include <linux/ioport.h> 54#include <linux/notifier.h> 55#include <linux/reboot.h> 56#include <linux/init.h> 57#include <linux/spinlock.h> 58 59#include <asm/io.h> 60#include <asm/uaccess.h> 61#include <asm/system.h> 62 63/* enable support for minutes as units? */ 64/* (does not always work correctly, so disabled by default!) */ 65#define SMSC_SUPPORT_MINUTES 66#undef SMSC_SUPPORT_MINUTES 67 68#define MAX_TIMEOUT 255 69 70#define UNIT_SECOND 0 71#define UNIT_MINUTE 1 72 73#define MODNAME "smsc37b787_wdt: " 74#define VERSION "1.1" 75 76#define IOPORT 0x3F0 77#define IOPORT_SIZE 2 78#define IODEV_NO 8 79 80static int unit = UNIT_SECOND; /* timer's unit */ 81static int timeout = 60; /* timeout value: default is 60 "units" */ 82static unsigned long timer_enabled = 0; /* is the timer enabled? */ 83 84static char expect_close; /* is the close expected? */ 85 86static spinlock_t io_lock; /* to guard the watchdog from io races */ 87 88static int nowayout = WATCHDOG_NOWAYOUT; 89 90/* -- Low level function ----------------------------------------*/ 91 92/* unlock the IO chip */ 93 94static 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 */ 102static inline void close_io_config(void) 103{ 104 outb(0xAA, IOPORT); 105} 106 107/* select the IO device */ 108static 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 */ 115static 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 */ 122static 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 130static 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 write_io_cr(0xE2, reg); 141} 142 143static inline void gpio_bit13(unsigned char reg) 144{ 145 // -- General Purpose I/O Bit 1.3 -- 146 // Bit 0, In/Out: 0 = Output, 1 = Input 147 // Bit 1, Polarity: 0 = No Invert, 1 = Invert 148 // Bit 2, Group Enable Intr.: 0 = Disable, 1 = Enable 149 // Bit 3, Function select: 0 = GPI/O, 1 = LED 150 // Bit 4-6 (Reserved) 151 // Bit 7, Output Type: 0 = Push Pull Bit, 1 = Open Drain 152 write_io_cr(0xE3, reg); 153} 154 155static inline void wdt_timer_units(unsigned char new_units) 156{ 157 // -- Watchdog timer units -- 158 // Bit 0-6 (Reserved) 159 // Bit 7, WDT Time-out Value Units Select 160 // (0 = Minutes, 1 = Seconds) 161 write_io_cr(0xF1, new_units); 162} 163 164static inline void wdt_timeout_value(unsigned char new_timeout) 165{ 166 // -- Watchdog Timer Time-out Value -- 167 // Bit 0-7 Binary coded units (0=Disabled, 1..255) 168 write_io_cr(0xF2, new_timeout); 169} 170 171static inline void wdt_timer_conf(unsigned char conf) 172{ 173 // -- Watchdog timer configuration -- 174 // Bit 0 Joystick enable: 0* = No Reset, 1 = Reset WDT upon Gameport I/O 175 // Bit 1 Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr. 176 // Bit 2 Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr. 177 // Bit 3 Reset the timer 178 // (Wrong in SMsC documentation? Given as: PowerLED Timout Enabled) 179 // Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled, 180 // 0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15) 181 write_io_cr(0xF3, conf); 182} 183 184static inline void wdt_timer_ctrl(unsigned char reg) 185{ 186 // -- Watchdog timer control -- 187 // Bit 0 Status Bit: 0 = Timer counting, 1 = Timeout occured 188 // Bit 1 Power LED Toggle: 0 = Disable Toggle, 1 = Toggle at 1 Hz 189 // Bit 2 Force Timeout: 1 = Forces WD timeout event (self-cleaning) 190 // Bit 3 P20 Force Timeout enabled: 191 // 0 = P20 activity does not generate the WD timeout event 192 // 1 = P20 Allows rising edge of P20, from the keyboard 193 // controller, to force the WD timeout event. 194 // Bit 4 (Reserved) 195 // -- Soft power management -- 196 // Bit 5 Stop Counter: 1 = Stop software power down counter 197 // set via register 0xB8, (self-cleaning) 198 // (Upon read: 0 = Counter running, 1 = Counter stopped) 199 // Bit 6 Restart Counter: 1 = Restart software power down counter 200 // set via register 0xB8, (self-cleaning) 201 // Bit 7 SPOFF: 1 = Force software power down (self-cleaning) 202 203 write_io_cr(0xF4, reg); 204} 205 206/* -- Higher level functions ------------------------------------*/ 207 208/* initialize watchdog */ 209 210static void wb_smsc_wdt_initialize(void) 211{ 212 unsigned char old; 213 214 spin_lock(&io_lock); 215 open_io_config(); 216 select_io_device(IODEV_NO); 217 218 // enable the watchdog 219 gpio_bit13(0x08); // Select pin 80 = LED not GPIO 220 gpio_bit12(0x0A); // Set pin 79 = WDT not GPIO/Output/Polarity=Invert 221 222 // disable the timeout 223 wdt_timeout_value(0); 224 225 // reset control register 226 wdt_timer_ctrl(0x00); 227 228 // reset configuration register 229 wdt_timer_conf(0x00); 230 231 // read old (timer units) register 232 old = read_io_cr(0xF1) & 0x7F; 233 if (unit == UNIT_SECOND) old |= 0x80; // set to seconds 234 235 // set the watchdog timer units 236 wdt_timer_units(old); 237 238 close_io_config(); 239 spin_unlock(&io_lock); 240} 241 242/* shutdown the watchdog */ 243 244static void wb_smsc_wdt_shutdown(void) 245{ 246 spin_lock(&io_lock); 247 open_io_config(); 248 select_io_device(IODEV_NO); 249 250 // disable the watchdog 251 gpio_bit13(0x09); 252 gpio_bit12(0x09); 253 254 // reset watchdog config register 255 wdt_timer_conf(0x00); 256 257 // reset watchdog control register 258 wdt_timer_ctrl(0x00); 259 260 // disable timeout 261 wdt_timeout_value(0x00); 262 263 close_io_config(); 264 spin_unlock(&io_lock); 265} 266 267/* set timeout => enable watchdog */ 268 269static void wb_smsc_wdt_set_timeout(unsigned char new_timeout) 270{ 271 spin_lock(&io_lock); 272 open_io_config(); 273 select_io_device(IODEV_NO); 274 275 // set Power LED to blink, if we enable the timeout 276 wdt_timer_ctrl((new_timeout == 0) ? 0x00 : 0x02); 277 278 // set timeout value 279 wdt_timeout_value(new_timeout); 280 281 close_io_config(); 282 spin_unlock(&io_lock); 283} 284 285/* get timeout */ 286 287static unsigned char wb_smsc_wdt_get_timeout(void) 288{ 289 unsigned char set_timeout; 290 291 spin_lock(&io_lock); 292 open_io_config(); 293 select_io_device(IODEV_NO); 294 set_timeout = read_io_cr(0xF2); 295 close_io_config(); 296 spin_unlock(&io_lock); 297 298 return set_timeout; 299} 300 301/* disable watchdog */ 302 303static void wb_smsc_wdt_disable(void) 304{ 305 // set the timeout to 0 to disable the watchdog 306 wb_smsc_wdt_set_timeout(0); 307} 308 309/* enable watchdog by setting the current timeout */ 310 311static void wb_smsc_wdt_enable(void) 312{ 313 // set the current timeout... 314 wb_smsc_wdt_set_timeout(timeout); 315} 316 317/* reset the timer */ 318 319static void wb_smsc_wdt_reset_timer(void) 320{ 321 spin_lock(&io_lock); 322 open_io_config(); 323 select_io_device(IODEV_NO); 324 325 // reset the timer 326 wdt_timeout_value(timeout); 327 wdt_timer_conf(0x08); 328 329 close_io_config(); 330 spin_unlock(&io_lock); 331} 332 333/* return, if the watchdog is enabled (timeout is set...) */ 334 335static int wb_smsc_wdt_status(void) 336{ 337 return (wb_smsc_wdt_get_timeout() == 0) ? 0 : WDIOF_KEEPALIVEPING; 338} 339 340 341/* -- File operations -------------------------------------------*/ 342 343/* open => enable watchdog and set initial timeout */ 344 345static int wb_smsc_wdt_open(struct inode *inode, struct file *file) 346{ 347 /* /dev/watchdog can only be opened once */ 348 349 if (test_and_set_bit(0, &timer_enabled)) 350 return -EBUSY; 351 352 if (nowayout) 353 __module_get(THIS_MODULE); 354 355 /* Reload and activate timer */ 356 wb_smsc_wdt_enable(); 357 358 printk(KERN_INFO MODNAME "Watchdog enabled. Timeout set to %d %s.\n", timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)"); 359 360 return nonseekable_open(inode, file); 361} 362 363/* close => shut off the timer */ 364 365static int wb_smsc_wdt_release(struct inode *inode, struct file *file) 366{ 367 /* Shut off the timer. */ 368 369 if (expect_close == 42) { 370 wb_smsc_wdt_disable(); 371 printk(KERN_INFO MODNAME "Watchdog disabled, sleeping again...\n"); 372 } else { 373 printk(KERN_CRIT MODNAME "Unexpected close, not stopping watchdog!\n"); 374 wb_smsc_wdt_reset_timer(); 375 } 376 377 clear_bit(0, &timer_enabled); 378 expect_close = 0; 379 return 0; 380} 381 382/* write => update the timer to keep the machine alive */ 383 384static ssize_t wb_smsc_wdt_write(struct file *file, const char __user *data, 385 size_t len, loff_t *ppos) 386{ 387 /* See if we got the magic character 'V' and reload the timer */ 388 if (len) { 389 if (!nowayout) { 390 size_t i; 391 392 /* reset expect flag */ 393 expect_close = 0; 394 395 /* scan to see whether or not we got the magic character */ 396 for (i = 0; i != len; i++) { 397 char c; 398 if (get_user(c, data+i)) 399 return -EFAULT; 400 if (c == 'V') 401 expect_close = 42; 402 } 403 } 404 405 /* someone wrote to us, we should reload the timer */ 406 wb_smsc_wdt_reset_timer(); 407 } 408 return len; 409} 410 411/* ioctl => control interface */ 412 413static int wb_smsc_wdt_ioctl(struct inode *inode, struct file *file, 414 unsigned int cmd, unsigned long arg) 415{ 416 int new_timeout; 417 418 union { 419 struct watchdog_info __user *ident; 420 int __user *i; 421 } uarg; 422 423 static struct watchdog_info ident = { 424 .options = WDIOF_KEEPALIVEPING | 425 WDIOF_SETTIMEOUT | 426 WDIOF_MAGICCLOSE, 427 .firmware_version = 0, 428 .identity = "SMsC 37B787 Watchdog" 429 }; 430 431 uarg.i = (int __user *)arg; 432 433 switch (cmd) { 434 default: 435 return -ENOTTY; 436 437 case WDIOC_GETSUPPORT: 438 return copy_to_user(uarg.ident, &ident, 439 sizeof(ident)) ? -EFAULT : 0; 440 441 case WDIOC_GETSTATUS: 442 return put_user(wb_smsc_wdt_status(), uarg.i); 443 444 case WDIOC_GETBOOTSTATUS: 445 return put_user(0, uarg.i); 446 447 case WDIOC_KEEPALIVE: 448 wb_smsc_wdt_reset_timer(); 449 return 0; 450 451 case WDIOC_SETTIMEOUT: 452 if (get_user(new_timeout, uarg.i)) 453 return -EFAULT; 454 455 // the API states this is given in secs 456 if (unit == UNIT_MINUTE) 457 new_timeout /= 60; 458 459 if (new_timeout < 0 || new_timeout > MAX_TIMEOUT) 460 return -EINVAL; 461 462 timeout = new_timeout; 463 wb_smsc_wdt_set_timeout(timeout); 464 465 // fall through and return the new timeout... 466 467 case WDIOC_GETTIMEOUT: 468 469 new_timeout = timeout; 470 471 if (unit == UNIT_MINUTE) 472 new_timeout *= 60; 473 474 return put_user(new_timeout, uarg.i); 475 476 case WDIOC_SETOPTIONS: 477 { 478 int options, retval = -EINVAL; 479 480 if (get_user(options, uarg.i)) 481 return -EFAULT; 482 483 if (options & WDIOS_DISABLECARD) { 484 wb_smsc_wdt_disable(); 485 retval = 0; 486 } 487 488 if (options & WDIOS_ENABLECARD) { 489 wb_smsc_wdt_enable(); 490 retval = 0; 491 } 492 493 return retval; 494 } 495 } 496} 497 498/* -- Notifier funtions -----------------------------------------*/ 499 500static int wb_smsc_wdt_notify_sys(struct notifier_block *this, unsigned long code, void *unused) 501{ 502 if (code == SYS_DOWN || code == SYS_HALT) 503 { 504 // set timeout to 0, to avoid possible race-condition 505 timeout = 0; 506 wb_smsc_wdt_disable(); 507 } 508 return NOTIFY_DONE; 509} 510 511/* -- Module's structures ---------------------------------------*/ 512 513static const struct file_operations wb_smsc_wdt_fops = 514{ 515 .owner = THIS_MODULE, 516 .llseek = no_llseek, 517 .write = wb_smsc_wdt_write, 518 .ioctl = wb_smsc_wdt_ioctl, 519 .open = wb_smsc_wdt_open, 520 .release = wb_smsc_wdt_release, 521}; 522 523static struct notifier_block wb_smsc_wdt_notifier = 524{ 525 .notifier_call = wb_smsc_wdt_notify_sys, 526}; 527 528static struct miscdevice wb_smsc_wdt_miscdev = 529{ 530 .minor = WATCHDOG_MINOR, 531 .name = "watchdog", 532 .fops = &wb_smsc_wdt_fops, 533}; 534 535/* -- Module init functions -------------------------------------*/ 536 537/* module's "constructor" */ 538 539static int __init wb_smsc_wdt_init(void) 540{ 541 int ret; 542 543 spin_lock_init(&io_lock); 544 545 printk("SMsC 37B787 watchdog component driver " VERSION " initialising...\n"); 546 547 if (!request_region(IOPORT, IOPORT_SIZE, "SMsC 37B787 watchdog")) { 548 printk(KERN_ERR MODNAME "Unable to register IO port %#x\n", IOPORT); 549 ret = -EBUSY; 550 goto out_pnp; 551 } 552 553 // set new maximum, if it's too big 554 if (timeout > MAX_TIMEOUT) 555 timeout = MAX_TIMEOUT; 556 557 // init the watchdog timer 558 wb_smsc_wdt_initialize(); 559 560 ret = register_reboot_notifier(&wb_smsc_wdt_notifier); 561 if (ret) { 562 printk(KERN_ERR MODNAME "Unable to register reboot notifier err = %d\n", ret); 563 goto out_io; 564 } 565 566 ret = misc_register(&wb_smsc_wdt_miscdev); 567 if (ret) { 568 printk(KERN_ERR MODNAME "Unable to register miscdev on minor %d\n", WATCHDOG_MINOR); 569 goto out_rbt; 570 } 571 572 // output info 573 printk(KERN_INFO MODNAME "Timeout set to %d %s.\n", timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)"); 574 printk(KERN_INFO MODNAME "Watchdog initialized and sleeping (nowayout=%d)...\n", nowayout); 575 576 // ret = 0 577 578out_clean: 579 return ret; 580 581out_rbt: 582 unregister_reboot_notifier(&wb_smsc_wdt_notifier); 583 584out_io: 585 release_region(IOPORT, IOPORT_SIZE); 586 587out_pnp: 588 goto out_clean; 589} 590 591/* module's "destructor" */ 592 593static void __exit wb_smsc_wdt_exit(void) 594{ 595 /* Stop the timer before we leave */ 596 if (!nowayout) 597 { 598 wb_smsc_wdt_shutdown(); 599 printk(KERN_INFO MODNAME "Watchdog disabled.\n"); 600 } 601 602 misc_deregister(&wb_smsc_wdt_miscdev); 603 unregister_reboot_notifier(&wb_smsc_wdt_notifier); 604 release_region(IOPORT, IOPORT_SIZE); 605 606 printk("SMsC 37B787 watchdog component driver removed.\n"); 607} 608 609module_init(wb_smsc_wdt_init); 610module_exit(wb_smsc_wdt_exit); 611 612MODULE_AUTHOR("Sven Anders <anders@anduras.de>"); 613MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version " VERSION ")"); 614MODULE_LICENSE("GPL"); 615 616MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 617 618#ifdef SMSC_SUPPORT_MINUTES 619module_param(unit, int, 0); 620MODULE_PARM_DESC(unit, "set unit to use, 0=seconds or 1=minutes, default is 0"); 621#endif 622 623module_param(timeout, int, 0); 624MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60"); 625 626module_param(nowayout, int, 0); 627MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 628