linux/drivers/watchdog/wdrtas.c
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   1/*
   2 * FIXME: add wdrtas_get_status and wdrtas_get_boot_status as soon as
   3 * RTAS calls are available
   4 */
   5
   6/*
   7 * RTAS watchdog driver
   8 *
   9 * (C) Copyright IBM Corp. 2005
  10 * device driver to exploit watchdog RTAS functions
  11 *
  12 * Authors : Utz Bacher <utz.bacher@de.ibm.com>
  13 *
  14 * This program is free software; you can redistribute it and/or modify
  15 * it under the terms of the GNU General Public License as published by
  16 * the Free Software Foundation; either version 2, or (at your option)
  17 * any later version.
  18 *
  19 * This program is distributed in the hope that it will be useful,
  20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22 * GNU General Public License for more details.
  23 *
  24 * You should have received a copy of the GNU General Public License
  25 * along with this program; if not, write to the Free Software
  26 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  27 */
  28
  29#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  30
  31#include <linux/fs.h>
  32#include <linux/init.h>
  33#include <linux/kernel.h>
  34#include <linux/miscdevice.h>
  35#include <linux/module.h>
  36#include <linux/notifier.h>
  37#include <linux/reboot.h>
  38#include <linux/types.h>
  39#include <linux/watchdog.h>
  40#include <linux/uaccess.h>
  41
  42#include <asm/rtas.h>
  43
  44#define WDRTAS_MAGIC_CHAR               42
  45#define WDRTAS_SUPPORTED_MASK           (WDIOF_SETTIMEOUT | \
  46                                         WDIOF_MAGICCLOSE)
  47
  48MODULE_AUTHOR("Utz Bacher <utz.bacher@de.ibm.com>");
  49MODULE_DESCRIPTION("RTAS watchdog driver");
  50MODULE_LICENSE("GPL");
  51MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  52MODULE_ALIAS_MISCDEV(TEMP_MINOR);
  53
  54static bool wdrtas_nowayout = WATCHDOG_NOWAYOUT;
  55static atomic_t wdrtas_miscdev_open = ATOMIC_INIT(0);
  56static char wdrtas_expect_close;
  57
  58static int wdrtas_interval;
  59
  60#define WDRTAS_THERMAL_SENSOR           3
  61static int wdrtas_token_get_sensor_state;
  62#define WDRTAS_SURVEILLANCE_IND         9000
  63static int wdrtas_token_set_indicator;
  64#define WDRTAS_SP_SPI                   28
  65static int wdrtas_token_get_sp;
  66static int wdrtas_token_event_scan;
  67
  68#define WDRTAS_DEFAULT_INTERVAL         300
  69
  70#define WDRTAS_LOGBUFFER_LEN            128
  71static char wdrtas_logbuffer[WDRTAS_LOGBUFFER_LEN];
  72
  73
  74/*** watchdog access functions */
  75
  76/**
  77 * wdrtas_set_interval - sets the watchdog interval
  78 * @interval: new interval
  79 *
  80 * returns 0 on success, <0 on failures
  81 *
  82 * wdrtas_set_interval sets the watchdog keepalive interval by calling the
  83 * RTAS function set-indicator (surveillance). The unit of interval is
  84 * seconds.
  85 */
  86
  87static int wdrtas_set_interval(int interval)
  88{
  89        long result;
  90        static int print_msg = 10;
  91
  92        /* rtas uses minutes */
  93        interval = (interval + 59) / 60;
  94
  95        result = rtas_call(wdrtas_token_set_indicator, 3, 1, NULL,
  96                           WDRTAS_SURVEILLANCE_IND, 0, interval);
  97        if (result < 0 && print_msg) {
  98                pr_err("setting the watchdog to %i timeout failed: %li\n",
  99                       interval, result);
 100                print_msg--;
 101        }
 102
 103        return result;
 104}
 105
 106#define WDRTAS_SP_SPI_LEN 4
 107
 108/**
 109 * wdrtas_get_interval - returns the current watchdog interval
 110 * @fallback_value: value (in seconds) to use, if the RTAS call fails
 111 *
 112 * returns the interval
 113 *
 114 * wdrtas_get_interval returns the current watchdog keepalive interval
 115 * as reported by the RTAS function ibm,get-system-parameter. The unit
 116 * of the return value is seconds.
 117 */
 118static int wdrtas_get_interval(int fallback_value)
 119{
 120        long result;
 121        char value[WDRTAS_SP_SPI_LEN];
 122
 123        spin_lock(&rtas_data_buf_lock);
 124        memset(rtas_data_buf, 0, WDRTAS_SP_SPI_LEN);
 125        result = rtas_call(wdrtas_token_get_sp, 3, 1, NULL,
 126                           WDRTAS_SP_SPI, __pa(rtas_data_buf),
 127                           WDRTAS_SP_SPI_LEN);
 128
 129        memcpy(value, rtas_data_buf, WDRTAS_SP_SPI_LEN);
 130        spin_unlock(&rtas_data_buf_lock);
 131
 132        if (value[0] != 0 || value[1] != 2 || value[3] != 0 || result < 0) {
 133                pr_warn("could not get sp_spi watchdog timeout (%li). Continuing\n",
 134                        result);
 135                return fallback_value;
 136        }
 137
 138        /* rtas uses minutes */
 139        return ((int)value[2]) * 60;
 140}
 141
 142/**
 143 * wdrtas_timer_start - starts watchdog
 144 *
 145 * wdrtas_timer_start starts the watchdog by calling the RTAS function
 146 * set-interval (surveillance)
 147 */
 148static void wdrtas_timer_start(void)
 149{
 150        wdrtas_set_interval(wdrtas_interval);
 151}
 152
 153/**
 154 * wdrtas_timer_stop - stops watchdog
 155 *
 156 * wdrtas_timer_stop stops the watchdog timer by calling the RTAS function
 157 * set-interval (surveillance)
 158 */
 159static void wdrtas_timer_stop(void)
 160{
 161        wdrtas_set_interval(0);
 162}
 163
 164/**
 165 * wdrtas_timer_keepalive - resets watchdog timer to keep system alive
 166 *
 167 * wdrtas_timer_keepalive restarts the watchdog timer by calling the
 168 * RTAS function event-scan and repeats these calls as long as there are
 169 * events available. All events will be dumped.
 170 */
 171static void wdrtas_timer_keepalive(void)
 172{
 173        long result;
 174
 175        do {
 176                result = rtas_call(wdrtas_token_event_scan, 4, 1, NULL,
 177                                   RTAS_EVENT_SCAN_ALL_EVENTS, 0,
 178                                   (void *)__pa(wdrtas_logbuffer),
 179                                   WDRTAS_LOGBUFFER_LEN);
 180                if (result < 0)
 181                        pr_err("event-scan failed: %li\n", result);
 182                if (result == 0)
 183                        print_hex_dump(KERN_INFO, "dumping event, data: ",
 184                                DUMP_PREFIX_OFFSET, 16, 1,
 185                                wdrtas_logbuffer, WDRTAS_LOGBUFFER_LEN, false);
 186        } while (result == 0);
 187}
 188
 189/**
 190 * wdrtas_get_temperature - returns current temperature
 191 *
 192 * returns temperature or <0 on failures
 193 *
 194 * wdrtas_get_temperature returns the current temperature in Fahrenheit. It
 195 * uses the RTAS call get-sensor-state, token 3 to do so
 196 */
 197static int wdrtas_get_temperature(void)
 198{
 199        int result;
 200        int temperature = 0;
 201
 202        result = rtas_get_sensor(WDRTAS_THERMAL_SENSOR, 0, &temperature);
 203
 204        if (result < 0)
 205                pr_warn("reading the thermal sensor failed: %i\n", result);
 206        else
 207                temperature = ((temperature * 9) / 5) + 32; /* fahrenheit */
 208
 209        return temperature;
 210}
 211
 212/**
 213 * wdrtas_get_status - returns the status of the watchdog
 214 *
 215 * returns a bitmask of defines WDIOF_... as defined in
 216 * include/linux/watchdog.h
 217 */
 218static int wdrtas_get_status(void)
 219{
 220        return 0; /* TODO */
 221}
 222
 223/**
 224 * wdrtas_get_boot_status - returns the reason for the last boot
 225 *
 226 * returns a bitmask of defines WDIOF_... as defined in
 227 * include/linux/watchdog.h, indicating why the watchdog rebooted the system
 228 */
 229static int wdrtas_get_boot_status(void)
 230{
 231        return 0; /* TODO */
 232}
 233
 234/*** watchdog API and operations stuff */
 235
 236/* wdrtas_write - called when watchdog device is written to
 237 * @file: file structure
 238 * @buf: user buffer with data
 239 * @len: amount to data written
 240 * @ppos: position in file
 241 *
 242 * returns the number of successfully processed characters, which is always
 243 * the number of bytes passed to this function
 244 *
 245 * wdrtas_write processes all the data given to it and looks for the magic
 246 * character 'V'. This character allows the watchdog device to be closed
 247 * properly.
 248 */
 249static ssize_t wdrtas_write(struct file *file, const char __user *buf,
 250             size_t len, loff_t *ppos)
 251{
 252        int i;
 253        char c;
 254
 255        if (!len)
 256                goto out;
 257
 258        if (!wdrtas_nowayout) {
 259                wdrtas_expect_close = 0;
 260                /* look for 'V' */
 261                for (i = 0; i < len; i++) {
 262                        if (get_user(c, buf + i))
 263                                return -EFAULT;
 264                        /* allow to close device */
 265                        if (c == 'V')
 266                                wdrtas_expect_close = WDRTAS_MAGIC_CHAR;
 267                }
 268        }
 269
 270        wdrtas_timer_keepalive();
 271
 272out:
 273        return len;
 274}
 275
 276/**
 277 * wdrtas_ioctl - ioctl function for the watchdog device
 278 * @file: file structure
 279 * @cmd: command for ioctl
 280 * @arg: argument pointer
 281 *
 282 * returns 0 on success, <0 on failure
 283 *
 284 * wdrtas_ioctl implements the watchdog API ioctls
 285 */
 286
 287static long wdrtas_ioctl(struct file *file, unsigned int cmd,
 288                                                        unsigned long arg)
 289{
 290        int __user *argp = (void __user *)arg;
 291        int i;
 292        static const struct watchdog_info wdinfo = {
 293                .options = WDRTAS_SUPPORTED_MASK,
 294                .firmware_version = 0,
 295                .identity = "wdrtas",
 296        };
 297
 298        switch (cmd) {
 299        case WDIOC_GETSUPPORT:
 300                if (copy_to_user(argp, &wdinfo, sizeof(wdinfo)))
 301                        return -EFAULT;
 302                return 0;
 303
 304        case WDIOC_GETSTATUS:
 305                i = wdrtas_get_status();
 306                return put_user(i, argp);
 307
 308        case WDIOC_GETBOOTSTATUS:
 309                i = wdrtas_get_boot_status();
 310                return put_user(i, argp);
 311
 312        case WDIOC_GETTEMP:
 313                if (wdrtas_token_get_sensor_state == RTAS_UNKNOWN_SERVICE)
 314                        return -EOPNOTSUPP;
 315
 316                i = wdrtas_get_temperature();
 317                return put_user(i, argp);
 318
 319        case WDIOC_SETOPTIONS:
 320                if (get_user(i, argp))
 321                        return -EFAULT;
 322                if (i & WDIOS_DISABLECARD)
 323                        wdrtas_timer_stop();
 324                if (i & WDIOS_ENABLECARD) {
 325                        wdrtas_timer_keepalive();
 326                        wdrtas_timer_start();
 327                }
 328                /* not implemented. Done by H8
 329                if (i & WDIOS_TEMPPANIC) {
 330                } */
 331                return 0;
 332
 333        case WDIOC_KEEPALIVE:
 334                wdrtas_timer_keepalive();
 335                return 0;
 336
 337        case WDIOC_SETTIMEOUT:
 338                if (get_user(i, argp))
 339                        return -EFAULT;
 340
 341                if (wdrtas_set_interval(i))
 342                        return -EINVAL;
 343
 344                wdrtas_timer_keepalive();
 345
 346                if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE)
 347                        wdrtas_interval = i;
 348                else
 349                        wdrtas_interval = wdrtas_get_interval(i);
 350                /* fallthrough */
 351
 352        case WDIOC_GETTIMEOUT:
 353                return put_user(wdrtas_interval, argp);
 354
 355        default:
 356                return -ENOTTY;
 357        }
 358}
 359
 360/**
 361 * wdrtas_open - open function of watchdog device
 362 * @inode: inode structure
 363 * @file: file structure
 364 *
 365 * returns 0 on success, -EBUSY if the file has been opened already, <0 on
 366 * other failures
 367 *
 368 * function called when watchdog device is opened
 369 */
 370static int wdrtas_open(struct inode *inode, struct file *file)
 371{
 372        /* only open once */
 373        if (atomic_inc_return(&wdrtas_miscdev_open) > 1) {
 374                atomic_dec(&wdrtas_miscdev_open);
 375                return -EBUSY;
 376        }
 377
 378        wdrtas_timer_start();
 379        wdrtas_timer_keepalive();
 380
 381        return nonseekable_open(inode, file);
 382}
 383
 384/**
 385 * wdrtas_close - close function of watchdog device
 386 * @inode: inode structure
 387 * @file: file structure
 388 *
 389 * returns 0 on success
 390 *
 391 * close function. Always succeeds
 392 */
 393static int wdrtas_close(struct inode *inode, struct file *file)
 394{
 395        /* only stop watchdog, if this was announced using 'V' before */
 396        if (wdrtas_expect_close == WDRTAS_MAGIC_CHAR)
 397                wdrtas_timer_stop();
 398        else {
 399                pr_warn("got unexpected close. Watchdog not stopped.\n");
 400                wdrtas_timer_keepalive();
 401        }
 402
 403        wdrtas_expect_close = 0;
 404        atomic_dec(&wdrtas_miscdev_open);
 405        return 0;
 406}
 407
 408/**
 409 * wdrtas_temp_read - gives back the temperature in fahrenheit
 410 * @file: file structure
 411 * @buf: user buffer
 412 * @count: number of bytes to be read
 413 * @ppos: position in file
 414 *
 415 * returns always 1 or -EFAULT in case of user space copy failures, <0 on
 416 * other failures
 417 *
 418 * wdrtas_temp_read gives the temperature to the users by copying this
 419 * value as one byte into the user space buffer. The unit is Fahrenheit...
 420 */
 421static ssize_t wdrtas_temp_read(struct file *file, char __user *buf,
 422                 size_t count, loff_t *ppos)
 423{
 424        int temperature = 0;
 425
 426        temperature = wdrtas_get_temperature();
 427        if (temperature < 0)
 428                return temperature;
 429
 430        if (copy_to_user(buf, &temperature, 1))
 431                return -EFAULT;
 432
 433        return 1;
 434}
 435
 436/**
 437 * wdrtas_temp_open - open function of temperature device
 438 * @inode: inode structure
 439 * @file: file structure
 440 *
 441 * returns 0 on success, <0 on failure
 442 *
 443 * function called when temperature device is opened
 444 */
 445static int wdrtas_temp_open(struct inode *inode, struct file *file)
 446{
 447        return nonseekable_open(inode, file);
 448}
 449
 450/**
 451 * wdrtas_temp_close - close function of temperature device
 452 * @inode: inode structure
 453 * @file: file structure
 454 *
 455 * returns 0 on success
 456 *
 457 * close function. Always succeeds
 458 */
 459static int wdrtas_temp_close(struct inode *inode, struct file *file)
 460{
 461        return 0;
 462}
 463
 464/**
 465 * wdrtas_reboot - reboot notifier function
 466 * @nb: notifier block structure
 467 * @code: reboot code
 468 * @ptr: unused
 469 *
 470 * returns NOTIFY_DONE
 471 *
 472 * wdrtas_reboot stops the watchdog in case of a reboot
 473 */
 474static int wdrtas_reboot(struct notifier_block *this,
 475                                        unsigned long code, void *ptr)
 476{
 477        if (code == SYS_DOWN || code == SYS_HALT)
 478                wdrtas_timer_stop();
 479
 480        return NOTIFY_DONE;
 481}
 482
 483/*** initialization stuff */
 484
 485static const struct file_operations wdrtas_fops = {
 486        .owner          = THIS_MODULE,
 487        .llseek         = no_llseek,
 488        .write          = wdrtas_write,
 489        .unlocked_ioctl = wdrtas_ioctl,
 490        .open           = wdrtas_open,
 491        .release        = wdrtas_close,
 492};
 493
 494static struct miscdevice wdrtas_miscdev = {
 495        .minor =        WATCHDOG_MINOR,
 496        .name =         "watchdog",
 497        .fops =         &wdrtas_fops,
 498};
 499
 500static const struct file_operations wdrtas_temp_fops = {
 501        .owner          = THIS_MODULE,
 502        .llseek         = no_llseek,
 503        .read           = wdrtas_temp_read,
 504        .open           = wdrtas_temp_open,
 505        .release        = wdrtas_temp_close,
 506};
 507
 508static struct miscdevice wdrtas_tempdev = {
 509        .minor =        TEMP_MINOR,
 510        .name =         "temperature",
 511        .fops =         &wdrtas_temp_fops,
 512};
 513
 514static struct notifier_block wdrtas_notifier = {
 515        .notifier_call =        wdrtas_reboot,
 516};
 517
 518/**
 519 * wdrtas_get_tokens - reads in RTAS tokens
 520 *
 521 * returns 0 on success, <0 on failure
 522 *
 523 * wdrtas_get_tokens reads in the tokens for the RTAS calls used in
 524 * this watchdog driver. It tolerates, if "get-sensor-state" and
 525 * "ibm,get-system-parameter" are not available.
 526 */
 527static int wdrtas_get_tokens(void)
 528{
 529        wdrtas_token_get_sensor_state = rtas_token("get-sensor-state");
 530        if (wdrtas_token_get_sensor_state == RTAS_UNKNOWN_SERVICE) {
 531                pr_warn("couldn't get token for get-sensor-state. Trying to continue without temperature support.\n");
 532        }
 533
 534        wdrtas_token_get_sp = rtas_token("ibm,get-system-parameter");
 535        if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE) {
 536                pr_warn("couldn't get token for ibm,get-system-parameter. Trying to continue with a default timeout value of %i seconds.\n",
 537                        WDRTAS_DEFAULT_INTERVAL);
 538        }
 539
 540        wdrtas_token_set_indicator = rtas_token("set-indicator");
 541        if (wdrtas_token_set_indicator == RTAS_UNKNOWN_SERVICE) {
 542                pr_err("couldn't get token for set-indicator. Terminating watchdog code.\n");
 543                return -EIO;
 544        }
 545
 546        wdrtas_token_event_scan = rtas_token("event-scan");
 547        if (wdrtas_token_event_scan == RTAS_UNKNOWN_SERVICE) {
 548                pr_err("couldn't get token for event-scan. Terminating watchdog code.\n");
 549                return -EIO;
 550        }
 551
 552        return 0;
 553}
 554
 555/**
 556 * wdrtas_unregister_devs - unregisters the misc dev handlers
 557 *
 558 * wdrtas_register_devs unregisters the watchdog and temperature watchdog
 559 * misc devs
 560 */
 561static void wdrtas_unregister_devs(void)
 562{
 563        misc_deregister(&wdrtas_miscdev);
 564        if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE)
 565                misc_deregister(&wdrtas_tempdev);
 566}
 567
 568/**
 569 * wdrtas_register_devs - registers the misc dev handlers
 570 *
 571 * returns 0 on success, <0 on failure
 572 *
 573 * wdrtas_register_devs registers the watchdog and temperature watchdog
 574 * misc devs
 575 */
 576static int wdrtas_register_devs(void)
 577{
 578        int result;
 579
 580        result = misc_register(&wdrtas_miscdev);
 581        if (result) {
 582                pr_err("couldn't register watchdog misc device. Terminating watchdog code.\n");
 583                return result;
 584        }
 585
 586        if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE) {
 587                result = misc_register(&wdrtas_tempdev);
 588                if (result) {
 589                        pr_warn("couldn't register watchdog temperature misc device. Continuing without temperature support.\n");
 590                        wdrtas_token_get_sensor_state = RTAS_UNKNOWN_SERVICE;
 591                }
 592        }
 593
 594        return 0;
 595}
 596
 597/**
 598 * wdrtas_init - init function of the watchdog driver
 599 *
 600 * returns 0 on success, <0 on failure
 601 *
 602 * registers the file handlers and the reboot notifier
 603 */
 604static int __init wdrtas_init(void)
 605{
 606        if (wdrtas_get_tokens())
 607                return -ENODEV;
 608
 609        if (wdrtas_register_devs())
 610                return -ENODEV;
 611
 612        if (register_reboot_notifier(&wdrtas_notifier)) {
 613                pr_err("could not register reboot notifier. Terminating watchdog code.\n");
 614                wdrtas_unregister_devs();
 615                return -ENODEV;
 616        }
 617
 618        if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE)
 619                wdrtas_interval = WDRTAS_DEFAULT_INTERVAL;
 620        else
 621                wdrtas_interval = wdrtas_get_interval(WDRTAS_DEFAULT_INTERVAL);
 622
 623        return 0;
 624}
 625
 626/**
 627 * wdrtas_exit - exit function of the watchdog driver
 628 *
 629 * unregisters the file handlers and the reboot notifier
 630 */
 631static void __exit wdrtas_exit(void)
 632{
 633        if (!wdrtas_nowayout)
 634                wdrtas_timer_stop();
 635
 636        wdrtas_unregister_devs();
 637
 638        unregister_reboot_notifier(&wdrtas_notifier);
 639}
 640
 641module_init(wdrtas_init);
 642module_exit(wdrtas_exit);
 643
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