drivers/char/watchdog/smsc37b787_wdt.c

   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
  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 = 0;   /* is the timer enabled? */
  83
  84 static char expect_close;       /* is the close expected? */
  85
  86 static spinlock_t io_lock;      /* to guard the watchdog from io races */
  87
  88 static int 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         write_io_cr(0xE2, reg);
 141 }
 142
 143 static 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
 155 static 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
 164 static 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
 171 static 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
 184 static 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
 210 static 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
 244 static 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
 269 static 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
 287 static 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
 303 static 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
 311 static 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
 319 static 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
 335 static 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
 345 static 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
 365 static 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
 384 static 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
 413 static 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
 500 static 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
 513 static 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
 523 static struct notifier_block wb_smsc_wdt_notifier =
 524 {
 525         .notifier_call  = wb_smsc_wdt_notify_sys,
 526 };
 527
 528 static 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
 539 static 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
 578 out_clean:
 579         return ret;
 580
 581 out_rbt:
 582         unregister_reboot_notifier(&wb_smsc_wdt_notifier);
 583
 584 out_io:
 585         release_region(IOPORT, IOPORT_SIZE);
 586
 587 out_pnp:
 588         goto out_clean;
 589 }
 590
 591 /* module's "destructor" */
 592
 593 static 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
 609 module_init(wb_smsc_wdt_init);
 610 module_exit(wb_smsc_wdt_exit);
 611
 612 MODULE_AUTHOR("Sven Anders <anders@anduras.de>");
 613 MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version " VERSION ")");
 614 MODULE_LICENSE("GPL");
 615
 616 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 617
 618 #ifdef SMSC_SUPPORT_MINUTES
 619 module_param(unit, int, 0);
 620 MODULE_PARM_DESC(unit, "set unit to use, 0=seconds or 1=minutes, default is 0");
 621 #endif
 622
 623 module_param(timeout, int, 0);
 624 MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60");
 625
 626 module_param(nowayout, int, 0);
 627 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");