root/drivers/watchdog/wdrtas.c

DEFINITIONS

1. wdrtas_set_interval
2. wdrtas_get_interval
3. wdrtas_timer_start
4. wdrtas_timer_stop
5. wdrtas_timer_keepalive
6. wdrtas_get_temperature
7. wdrtas_get_status
8. wdrtas_get_boot_status
9. wdrtas_write
10. wdrtas_ioctl
11. wdrtas_open
12. wdrtas_close
13. wdrtas_temp_read
14. wdrtas_temp_open
15. wdrtas_temp_close
16. wdrtas_reboot
17. wdrtas_get_tokens
18. wdrtas_unregister_devs
19. wdrtas_register_devs
20. wdrtas_init
21. wdrtas_exit

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * FIXME: add wdrtas_get_status and wdrtas_get_boot_status as soon as
   4  * RTAS calls are available
   5  */
   6 
   7 /*
   8  * RTAS watchdog driver
   9  *
  10  * (C) Copyright IBM Corp. 2005
  11  * device driver to exploit watchdog RTAS functions
  12  *
  13  * Authors : Utz Bacher <utz.bacher@de.ibm.com>
  14  */
  15 
  16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  17 
  18 #include <linux/fs.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/miscdevice.h>
  22 #include <linux/module.h>
  23 #include <linux/notifier.h>
  24 #include <linux/reboot.h>
  25 #include <linux/types.h>
  26 #include <linux/watchdog.h>
  27 #include <linux/uaccess.h>
  28 
  29 #include <asm/rtas.h>
  30 
  31 #define WDRTAS_MAGIC_CHAR               42
  32 #define WDRTAS_SUPPORTED_MASK           (WDIOF_SETTIMEOUT | \
  33                                          WDIOF_MAGICCLOSE)
  34 
  35 MODULE_AUTHOR("Utz Bacher <utz.bacher@de.ibm.com>");
  36 MODULE_DESCRIPTION("RTAS watchdog driver");
  37 MODULE_LICENSE("GPL");
  38 
  39 static bool wdrtas_nowayout = WATCHDOG_NOWAYOUT;
  40 static atomic_t wdrtas_miscdev_open = ATOMIC_INIT(0);
  41 static char wdrtas_expect_close;
  42 
  43 static int wdrtas_interval;
  44 
  45 #define WDRTAS_THERMAL_SENSOR           3
  46 static int wdrtas_token_get_sensor_state;
  47 #define WDRTAS_SURVEILLANCE_IND         9000
  48 static int wdrtas_token_set_indicator;
  49 #define WDRTAS_SP_SPI                   28
  50 static int wdrtas_token_get_sp;
  51 static int wdrtas_token_event_scan;
  52 
  53 #define WDRTAS_DEFAULT_INTERVAL         300
  54 
  55 #define WDRTAS_LOGBUFFER_LEN            128
  56 static char wdrtas_logbuffer[WDRTAS_LOGBUFFER_LEN];
  57 
  58 
  59 /*** watchdog access functions */
  60 
  61 /**
  62  * wdrtas_set_interval - sets the watchdog interval
  63  * @interval: new interval
  64  *
  65  * returns 0 on success, <0 on failures
  66  *
  67  * wdrtas_set_interval sets the watchdog keepalive interval by calling the
  68  * RTAS function set-indicator (surveillance). The unit of interval is
  69  * seconds.
  70  */
  71 
  72 static int wdrtas_set_interval(int interval)
  73 {
  74         long result;
  75         static int print_msg = 10;
  76 
  77         /* rtas uses minutes */
  78         interval = (interval + 59) / 60;
  79 
  80         result = rtas_call(wdrtas_token_set_indicator, 3, 1, NULL,
  81                            WDRTAS_SURVEILLANCE_IND, 0, interval);
  82         if (result < 0 && print_msg) {
  83                 pr_err("setting the watchdog to %i timeout failed: %li\n",
  84                        interval, result);
  85                 print_msg--;
  86         }
  87 
  88         return result;
  89 }
  90 
  91 #define WDRTAS_SP_SPI_LEN 4
  92 
  93 /**
  94  * wdrtas_get_interval - returns the current watchdog interval
  95  * @fallback_value: value (in seconds) to use, if the RTAS call fails
  96  *
  97  * returns the interval
  98  *
  99  * wdrtas_get_interval returns the current watchdog keepalive interval
 100  * as reported by the RTAS function ibm,get-system-parameter. The unit
 101  * of the return value is seconds.
 102  */
 103 static int wdrtas_get_interval(int fallback_value)
 104 {
 105         long result;
 106         char value[WDRTAS_SP_SPI_LEN];
 107 
 108         spin_lock(&rtas_data_buf_lock);
 109         memset(rtas_data_buf, 0, WDRTAS_SP_SPI_LEN);
 110         result = rtas_call(wdrtas_token_get_sp, 3, 1, NULL,
 111                            WDRTAS_SP_SPI, __pa(rtas_data_buf),
 112                            WDRTAS_SP_SPI_LEN);
 113 
 114         memcpy(value, rtas_data_buf, WDRTAS_SP_SPI_LEN);
 115         spin_unlock(&rtas_data_buf_lock);
 116 
 117         if (value[0] != 0 || value[1] != 2 || value[3] != 0 || result < 0) {
 118                 pr_warn("could not get sp_spi watchdog timeout (%li). Continuing\n",
 119                         result);
 120                 return fallback_value;
 121         }
 122 
 123         /* rtas uses minutes */
 124         return ((int)value[2]) * 60;
 125 }
 126 
 127 /**
 128  * wdrtas_timer_start - starts watchdog
 129  *
 130  * wdrtas_timer_start starts the watchdog by calling the RTAS function
 131  * set-interval (surveillance)
 132  */
 133 static void wdrtas_timer_start(void)
 134 {
 135         wdrtas_set_interval(wdrtas_interval);
 136 }
 137 
 138 /**
 139  * wdrtas_timer_stop - stops watchdog
 140  *
 141  * wdrtas_timer_stop stops the watchdog timer by calling the RTAS function
 142  * set-interval (surveillance)
 143  */
 144 static void wdrtas_timer_stop(void)
 145 {
 146         wdrtas_set_interval(0);
 147 }
 148 
 149 /**
 150  * wdrtas_timer_keepalive - resets watchdog timer to keep system alive
 151  *
 152  * wdrtas_timer_keepalive restarts the watchdog timer by calling the
 153  * RTAS function event-scan and repeats these calls as long as there are
 154  * events available. All events will be dumped.
 155  */
 156 static void wdrtas_timer_keepalive(void)
 157 {
 158         long result;
 159 
 160         do {
 161                 result = rtas_call(wdrtas_token_event_scan, 4, 1, NULL,
 162                                    RTAS_EVENT_SCAN_ALL_EVENTS, 0,
 163                                    (void *)__pa(wdrtas_logbuffer),
 164                                    WDRTAS_LOGBUFFER_LEN);
 165                 if (result < 0)
 166                         pr_err("event-scan failed: %li\n", result);
 167                 if (result == 0)
 168                         print_hex_dump(KERN_INFO, "dumping event, data: ",
 169                                 DUMP_PREFIX_OFFSET, 16, 1,
 170                                 wdrtas_logbuffer, WDRTAS_LOGBUFFER_LEN, false);
 171         } while (result == 0);
 172 }
 173 
 174 /**
 175  * wdrtas_get_temperature - returns current temperature
 176  *
 177  * returns temperature or <0 on failures
 178  *
 179  * wdrtas_get_temperature returns the current temperature in Fahrenheit. It
 180  * uses the RTAS call get-sensor-state, token 3 to do so
 181  */
 182 static int wdrtas_get_temperature(void)
 183 {
 184         int result;
 185         int temperature = 0;
 186 
 187         result = rtas_get_sensor(WDRTAS_THERMAL_SENSOR, 0, &temperature);
 188 
 189         if (result < 0)
 190                 pr_warn("reading the thermal sensor failed: %i\n", result);
 191         else
 192                 temperature = ((temperature * 9) / 5) + 32; /* fahrenheit */
 193 
 194         return temperature;
 195 }
 196 
 197 /**
 198  * wdrtas_get_status - returns the status of the watchdog
 199  *
 200  * returns a bitmask of defines WDIOF_... as defined in
 201  * include/linux/watchdog.h
 202  */
 203 static int wdrtas_get_status(void)
 204 {
 205         return 0; /* TODO */
 206 }
 207 
 208 /**
 209  * wdrtas_get_boot_status - returns the reason for the last boot
 210  *
 211  * returns a bitmask of defines WDIOF_... as defined in
 212  * include/linux/watchdog.h, indicating why the watchdog rebooted the system
 213  */
 214 static int wdrtas_get_boot_status(void)
 215 {
 216         return 0; /* TODO */
 217 }
 218 
 219 /*** watchdog API and operations stuff */
 220 
 221 /* wdrtas_write - called when watchdog device is written to
 222  * @file: file structure
 223  * @buf: user buffer with data
 224  * @len: amount to data written
 225  * @ppos: position in file
 226  *
 227  * returns the number of successfully processed characters, which is always
 228  * the number of bytes passed to this function
 229  *
 230  * wdrtas_write processes all the data given to it and looks for the magic
 231  * character 'V'. This character allows the watchdog device to be closed
 232  * properly.
 233  */
 234 static ssize_t wdrtas_write(struct file *file, const char __user *buf,
 235              size_t len, loff_t *ppos)
 236 {
 237         int i;
 238         char c;
 239 
 240         if (!len)
 241                 goto out;
 242 
 243         if (!wdrtas_nowayout) {
 244                 wdrtas_expect_close = 0;
 245                 /* look for 'V' */
 246                 for (i = 0; i < len; i++) {
 247                         if (get_user(c, buf + i))
 248                                 return -EFAULT;
 249                         /* allow to close device */
 250                         if (c == 'V')
 251                                 wdrtas_expect_close = WDRTAS_MAGIC_CHAR;
 252                 }
 253         }
 254 
 255         wdrtas_timer_keepalive();
 256 
 257 out:
 258         return len;
 259 }
 260 
 261 /**
 262  * wdrtas_ioctl - ioctl function for the watchdog device
 263  * @file: file structure
 264  * @cmd: command for ioctl
 265  * @arg: argument pointer
 266  *
 267  * returns 0 on success, <0 on failure
 268  *
 269  * wdrtas_ioctl implements the watchdog API ioctls
 270  */
 271 
 272 static long wdrtas_ioctl(struct file *file, unsigned int cmd,
 273                                                         unsigned long arg)
 274 {
 275         int __user *argp = (void __user *)arg;
 276         int i;
 277         static const struct watchdog_info wdinfo = {
 278                 .options = WDRTAS_SUPPORTED_MASK,
 279                 .firmware_version = 0,
 280                 .identity = "wdrtas",
 281         };
 282 
 283         switch (cmd) {
 284         case WDIOC_GETSUPPORT:
 285                 if (copy_to_user(argp, &wdinfo, sizeof(wdinfo)))
 286                         return -EFAULT;
 287                 return 0;
 288 
 289         case WDIOC_GETSTATUS:
 290                 i = wdrtas_get_status();
 291                 return put_user(i, argp);
 292 
 293         case WDIOC_GETBOOTSTATUS:
 294                 i = wdrtas_get_boot_status();
 295                 return put_user(i, argp);
 296 
 297         case WDIOC_GETTEMP:
 298                 if (wdrtas_token_get_sensor_state == RTAS_UNKNOWN_SERVICE)
 299                         return -EOPNOTSUPP;
 300 
 301                 i = wdrtas_get_temperature();
 302                 return put_user(i, argp);
 303 
 304         case WDIOC_SETOPTIONS:
 305                 if (get_user(i, argp))
 306                         return -EFAULT;
 307                 if (i & WDIOS_DISABLECARD)
 308                         wdrtas_timer_stop();
 309                 if (i & WDIOS_ENABLECARD) {
 310                         wdrtas_timer_keepalive();
 311                         wdrtas_timer_start();
 312                 }
 313                 /* not implemented. Done by H8
 314                 if (i & WDIOS_TEMPPANIC) {
 315                 } */
 316                 return 0;
 317 
 318         case WDIOC_KEEPALIVE:
 319                 wdrtas_timer_keepalive();
 320                 return 0;
 321 
 322         case WDIOC_SETTIMEOUT:
 323                 if (get_user(i, argp))
 324                         return -EFAULT;
 325 
 326                 if (wdrtas_set_interval(i))
 327                         return -EINVAL;
 328 
 329                 wdrtas_timer_keepalive();
 330 
 331                 if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE)
 332                         wdrtas_interval = i;
 333                 else
 334                         wdrtas_interval = wdrtas_get_interval(i);
 335                 /* fallthrough */
 336 
 337         case WDIOC_GETTIMEOUT:
 338                 return put_user(wdrtas_interval, argp);
 339 
 340         default:
 341                 return -ENOTTY;
 342         }
 343 }
 344 
 345 /**
 346  * wdrtas_open - open function of watchdog device
 347  * @inode: inode structure
 348  * @file: file structure
 349  *
 350  * returns 0 on success, -EBUSY if the file has been opened already, <0 on
 351  * other failures
 352  *
 353  * function called when watchdog device is opened
 354  */
 355 static int wdrtas_open(struct inode *inode, struct file *file)
 356 {
 357         /* only open once */
 358         if (atomic_inc_return(&wdrtas_miscdev_open) > 1) {
 359                 atomic_dec(&wdrtas_miscdev_open);
 360                 return -EBUSY;
 361         }
 362 
 363         wdrtas_timer_start();
 364         wdrtas_timer_keepalive();
 365 
 366         return stream_open(inode, file);
 367 }
 368 
 369 /**
 370  * wdrtas_close - close function of watchdog device
 371  * @inode: inode structure
 372  * @file: file structure
 373  *
 374  * returns 0 on success
 375  *
 376  * close function. Always succeeds
 377  */
 378 static int wdrtas_close(struct inode *inode, struct file *file)
 379 {
 380         /* only stop watchdog, if this was announced using 'V' before */
 381         if (wdrtas_expect_close == WDRTAS_MAGIC_CHAR)
 382                 wdrtas_timer_stop();
 383         else {
 384                 pr_warn("got unexpected close. Watchdog not stopped.\n");
 385                 wdrtas_timer_keepalive();
 386         }
 387 
 388         wdrtas_expect_close = 0;
 389         atomic_dec(&wdrtas_miscdev_open);
 390         return 0;
 391 }
 392 
 393 /**
 394  * wdrtas_temp_read - gives back the temperature in fahrenheit
 395  * @file: file structure
 396  * @buf: user buffer
 397  * @count: number of bytes to be read
 398  * @ppos: position in file
 399  *
 400  * returns always 1 or -EFAULT in case of user space copy failures, <0 on
 401  * other failures
 402  *
 403  * wdrtas_temp_read gives the temperature to the users by copying this
 404  * value as one byte into the user space buffer. The unit is Fahrenheit...
 405  */
 406 static ssize_t wdrtas_temp_read(struct file *file, char __user *buf,
 407                  size_t count, loff_t *ppos)
 408 {
 409         int temperature = 0;
 410 
 411         temperature = wdrtas_get_temperature();
 412         if (temperature < 0)
 413                 return temperature;
 414 
 415         if (copy_to_user(buf, &temperature, 1))
 416                 return -EFAULT;
 417 
 418         return 1;
 419 }
 420 
 421 /**
 422  * wdrtas_temp_open - open function of temperature device
 423  * @inode: inode structure
 424  * @file: file structure
 425  *
 426  * returns 0 on success, <0 on failure
 427  *
 428  * function called when temperature device is opened
 429  */
 430 static int wdrtas_temp_open(struct inode *inode, struct file *file)
 431 {
 432         return stream_open(inode, file);
 433 }
 434 
 435 /**
 436  * wdrtas_temp_close - close function of temperature device
 437  * @inode: inode structure
 438  * @file: file structure
 439  *
 440  * returns 0 on success
 441  *
 442  * close function. Always succeeds
 443  */
 444 static int wdrtas_temp_close(struct inode *inode, struct file *file)
 445 {
 446         return 0;
 447 }
 448 
 449 /**
 450  * wdrtas_reboot - reboot notifier function
 451  * @nb: notifier block structure
 452  * @code: reboot code
 453  * @ptr: unused
 454  *
 455  * returns NOTIFY_DONE
 456  *
 457  * wdrtas_reboot stops the watchdog in case of a reboot
 458  */
 459 static int wdrtas_reboot(struct notifier_block *this,
 460                                         unsigned long code, void *ptr)
 461 {
 462         if (code == SYS_DOWN || code == SYS_HALT)
 463                 wdrtas_timer_stop();
 464 
 465         return NOTIFY_DONE;
 466 }
 467 
 468 /*** initialization stuff */
 469 
 470 static const struct file_operations wdrtas_fops = {
 471         .owner          = THIS_MODULE,
 472         .llseek         = no_llseek,
 473         .write          = wdrtas_write,
 474         .unlocked_ioctl = wdrtas_ioctl,
 475         .open           = wdrtas_open,
 476         .release        = wdrtas_close,
 477 };
 478 
 479 static struct miscdevice wdrtas_miscdev = {
 480         .minor =        WATCHDOG_MINOR,
 481         .name =         "watchdog",
 482         .fops =         &wdrtas_fops,
 483 };
 484 
 485 static const struct file_operations wdrtas_temp_fops = {
 486         .owner          = THIS_MODULE,
 487         .llseek         = no_llseek,
 488         .read           = wdrtas_temp_read,
 489         .open           = wdrtas_temp_open,
 490         .release        = wdrtas_temp_close,
 491 };
 492 
 493 static struct miscdevice wdrtas_tempdev = {
 494         .minor =        TEMP_MINOR,
 495         .name =         "temperature",
 496         .fops =         &wdrtas_temp_fops,
 497 };
 498 
 499 static struct notifier_block wdrtas_notifier = {
 500         .notifier_call =        wdrtas_reboot,
 501 };
 502 
 503 /**
 504  * wdrtas_get_tokens - reads in RTAS tokens
 505  *
 506  * returns 0 on success, <0 on failure
 507  *
 508  * wdrtas_get_tokens reads in the tokens for the RTAS calls used in
 509  * this watchdog driver. It tolerates, if "get-sensor-state" and
 510  * "ibm,get-system-parameter" are not available.
 511  */
 512 static int wdrtas_get_tokens(void)
 513 {
 514         wdrtas_token_get_sensor_state = rtas_token("get-sensor-state");
 515         if (wdrtas_token_get_sensor_state == RTAS_UNKNOWN_SERVICE) {
 516                 pr_warn("couldn't get token for get-sensor-state. Trying to continue without temperature support.\n");
 517         }
 518 
 519         wdrtas_token_get_sp = rtas_token("ibm,get-system-parameter");
 520         if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE) {
 521                 pr_warn("couldn't get token for ibm,get-system-parameter. Trying to continue with a default timeout value of %i seconds.\n",
 522                         WDRTAS_DEFAULT_INTERVAL);
 523         }
 524 
 525         wdrtas_token_set_indicator = rtas_token("set-indicator");
 526         if (wdrtas_token_set_indicator == RTAS_UNKNOWN_SERVICE) {
 527                 pr_err("couldn't get token for set-indicator. Terminating watchdog code.\n");
 528                 return -EIO;
 529         }
 530 
 531         wdrtas_token_event_scan = rtas_token("event-scan");
 532         if (wdrtas_token_event_scan == RTAS_UNKNOWN_SERVICE) {
 533                 pr_err("couldn't get token for event-scan. Terminating watchdog code.\n");
 534                 return -EIO;
 535         }
 536 
 537         return 0;
 538 }
 539 
 540 /**
 541  * wdrtas_unregister_devs - unregisters the misc dev handlers
 542  *
 543  * wdrtas_register_devs unregisters the watchdog and temperature watchdog
 544  * misc devs
 545  */
 546 static void wdrtas_unregister_devs(void)
 547 {
 548         misc_deregister(&wdrtas_miscdev);
 549         if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE)
 550                 misc_deregister(&wdrtas_tempdev);
 551 }
 552 
 553 /**
 554  * wdrtas_register_devs - registers the misc dev handlers
 555  *
 556  * returns 0 on success, <0 on failure
 557  *
 558  * wdrtas_register_devs registers the watchdog and temperature watchdog
 559  * misc devs
 560  */
 561 static int wdrtas_register_devs(void)
 562 {
 563         int result;
 564 
 565         result = misc_register(&wdrtas_miscdev);
 566         if (result) {
 567                 pr_err("couldn't register watchdog misc device. Terminating watchdog code.\n");
 568                 return result;
 569         }
 570 
 571         if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE) {
 572                 result = misc_register(&wdrtas_tempdev);
 573                 if (result) {
 574                         pr_warn("couldn't register watchdog temperature misc device. Continuing without temperature support.\n");
 575                         wdrtas_token_get_sensor_state = RTAS_UNKNOWN_SERVICE;
 576                 }
 577         }
 578 
 579         return 0;
 580 }
 581 
 582 /**
 583  * wdrtas_init - init function of the watchdog driver
 584  *
 585  * returns 0 on success, <0 on failure
 586  *
 587  * registers the file handlers and the reboot notifier
 588  */
 589 static int __init wdrtas_init(void)
 590 {
 591         if (wdrtas_get_tokens())
 592                 return -ENODEV;
 593 
 594         if (wdrtas_register_devs())
 595                 return -ENODEV;
 596 
 597         if (register_reboot_notifier(&wdrtas_notifier)) {
 598                 pr_err("could not register reboot notifier. Terminating watchdog code.\n");
 599                 wdrtas_unregister_devs();
 600                 return -ENODEV;
 601         }
 602 
 603         if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE)
 604                 wdrtas_interval = WDRTAS_DEFAULT_INTERVAL;
 605         else
 606                 wdrtas_interval = wdrtas_get_interval(WDRTAS_DEFAULT_INTERVAL);
 607 
 608         return 0;
 609 }
 610 
 611 /**
 612  * wdrtas_exit - exit function of the watchdog driver
 613  *
 614  * unregisters the file handlers and the reboot notifier
 615  */
 616 static void __exit wdrtas_exit(void)
 617 {
 618         if (!wdrtas_nowayout)
 619                 wdrtas_timer_stop();
 620 
 621         wdrtas_unregister_devs();
 622 
 623         unregister_reboot_notifier(&wdrtas_notifier);
 624 }
 625 
 626 module_init(wdrtas_init);
 627 module_exit(wdrtas_exit);