drivers/watchdog/watchdog_dev.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *      watchdog_dev.c
   4  *
   5  *      (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
   6  *                                              All Rights Reserved.
   7  *
   8  *      (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
   9  *
  10  *      (c) Copyright 2021 Hewlett Packard Enterprise Development LP.
  11  *
  12  *      This source code is part of the generic code that can be used
  13  *      by all the watchdog timer drivers.
  14  *
  15  *      This part of the generic code takes care of the following
  16  *      misc device: /dev/watchdog.
  17  *
  18  *      Based on source code of the following authors:
  19  *        Matt Domsch <Matt_Domsch@dell.com>,
  20  *        Rob Radez <rob@osinvestor.com>,
  21  *        Rusty Lynch <rusty@linux.co.intel.com>
  22  *        Satyam Sharma <satyam@infradead.org>
  23  *        Randy Dunlap <randy.dunlap@oracle.com>
  24  *
  25  *      Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
  26  *      admit liability nor provide warranty for any of this software.
  27  *      This material is provided "AS-IS" and at no charge.
  28  */
  29
  30 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  31
  32 #include <linux/cdev.h>         /* For character device */
  33 #include <linux/errno.h>        /* For the -ENODEV/... values */
  34 #include <linux/fs.h>           /* For file operations */
  35 #include <linux/init.h>         /* For __init/__exit/... */
  36 #include <linux/hrtimer.h>      /* For hrtimers */
  37 #include <linux/kernel.h>       /* For printk/panic/... */
  38 #include <linux/kthread.h>      /* For kthread_work */
  39 #include <linux/miscdevice.h>   /* For handling misc devices */
  40 #include <linux/module.h>       /* For module stuff/... */
  41 #include <linux/mutex.h>        /* For mutexes */
  42 #include <linux/slab.h>         /* For memory functions */
  43 #include <linux/types.h>        /* For standard types (like size_t) */
  44 #include <linux/watchdog.h>     /* For watchdog specific items */
  45 #include <linux/uaccess.h>      /* For copy_to_user/put_user/... */
  46
  47 #include "watchdog_core.h"
  48 #include "watchdog_pretimeout.h"
  49
  50 /* the dev_t structure to store the dynamically allocated watchdog devices */
  51 static dev_t watchdog_devt;
  52 /* Reference to watchdog device behind /dev/watchdog */
  53 static struct watchdog_core_data *old_wd_data;
  54
  55 static struct kthread_worker *watchdog_kworker;
  56
  57 static bool handle_boot_enabled =
  58         IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
  59
  60 static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT;
  61
  62 static bool watchdog_past_open_deadline(struct watchdog_core_data *data)
  63 {
  64         return ktime_after(ktime_get(), data->open_deadline);
  65 }
  66
  67 static void watchdog_set_open_deadline(struct watchdog_core_data *data)
  68 {
  69         data->open_deadline = open_timeout ?
  70                 ktime_get() + ktime_set(open_timeout, 0) : KTIME_MAX;
  71 }
  72
  73 static inline bool watchdog_need_worker(struct watchdog_device *wdd)
  74 {
  75         /* All variables in milli-seconds */
  76         unsigned int hm = wdd->max_hw_heartbeat_ms;
  77         unsigned int t = wdd->timeout * 1000;
  78
  79         /*
  80          * A worker to generate heartbeat requests is needed if all of the
  81          * following conditions are true.
  82          * - Userspace activated the watchdog.
  83          * - The driver provided a value for the maximum hardware timeout, and
  84          *   thus is aware that the framework supports generating heartbeat
  85          *   requests.
  86          * - Userspace requests a longer timeout than the hardware can handle.
  87          *
  88          * Alternatively, if userspace has not opened the watchdog
  89          * device, we take care of feeding the watchdog if it is
  90          * running.
  91          */
  92         return (hm && watchdog_active(wdd) && t > hm) ||
  93                 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
  94 }
  95
  96 static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd)
  97 {
  98         struct watchdog_core_data *wd_data = wdd->wd_data;
  99         unsigned int timeout_ms = wdd->timeout * 1000;
 100         ktime_t keepalive_interval;
 101         ktime_t last_heartbeat, latest_heartbeat;
 102         ktime_t virt_timeout;
 103         unsigned int hw_heartbeat_ms;
 104
 105         if (watchdog_active(wdd))
 106                 virt_timeout = ktime_add(wd_data->last_keepalive,
 107                                          ms_to_ktime(timeout_ms));
 108         else
 109                 virt_timeout = wd_data->open_deadline;
 110
 111         hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
 112         keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);
 113
 114         /*
 115          * To ensure that the watchdog times out wdd->timeout seconds
 116          * after the most recent ping from userspace, the last
 117          * worker ping has to come in hw_heartbeat_ms before this timeout.
 118          */
 119         last_heartbeat = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms));
 120         latest_heartbeat = ktime_sub(last_heartbeat, ktime_get());
 121         if (ktime_before(latest_heartbeat, keepalive_interval))
 122                 return latest_heartbeat;
 123         return keepalive_interval;
 124 }
 125
 126 static inline void watchdog_update_worker(struct watchdog_device *wdd)
 127 {
 128         struct watchdog_core_data *wd_data = wdd->wd_data;
 129
 130         if (watchdog_need_worker(wdd)) {
 131                 ktime_t t = watchdog_next_keepalive(wdd);
 132
 133                 if (t > 0)
 134                         hrtimer_start(&wd_data->timer, t,
 135                                       HRTIMER_MODE_REL_HARD);
 136         } else {
 137                 hrtimer_cancel(&wd_data->timer);
 138         }
 139 }
 140
 141 static int __watchdog_ping(struct watchdog_device *wdd)
 142 {
 143         struct watchdog_core_data *wd_data = wdd->wd_data;
 144         ktime_t earliest_keepalive, now;
 145         int err;
 146
 147         earliest_keepalive = ktime_add(wd_data->last_hw_keepalive,
 148                                        ms_to_ktime(wdd->min_hw_heartbeat_ms));
 149         now = ktime_get();
 150
 151         if (ktime_after(earliest_keepalive, now)) {
 152                 hrtimer_start(&wd_data->timer,
 153                               ktime_sub(earliest_keepalive, now),
 154                               HRTIMER_MODE_REL_HARD);
 155                 return 0;
 156         }
 157
 158         wd_data->last_hw_keepalive = now;
 159
 160         if (wdd->ops->ping)
 161                 err = wdd->ops->ping(wdd);  /* ping the watchdog */
 162         else
 163                 err = wdd->ops->start(wdd); /* restart watchdog */
 164
 165         if (err == 0)
 166                 watchdog_hrtimer_pretimeout_start(wdd);
 167
 168         watchdog_update_worker(wdd);
 169
 170         return err;
 171 }
 172
 173 /*
 174  * watchdog_ping - ping the watchdog
 175  * @wdd: The watchdog device to ping
 176  *
 177  * If the watchdog has no own ping operation then it needs to be
 178  * restarted via the start operation. This wrapper function does
 179  * exactly that.
 180  * We only ping when the watchdog device is running.
 181  * The caller must hold wd_data->lock.
 182  *
 183  * Return: 0 on success, error otherwise.
 184  */
 185 static int watchdog_ping(struct watchdog_device *wdd)
 186 {
 187         struct watchdog_core_data *wd_data = wdd->wd_data;
 188
 189         if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
 190                 return 0;
 191
 192         set_bit(_WDOG_KEEPALIVE, &wd_data->status);
 193
 194         wd_data->last_keepalive = ktime_get();
 195         return __watchdog_ping(wdd);
 196 }
 197
 198 static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data)
 199 {
 200         struct watchdog_device *wdd = wd_data->wdd;
 201
 202         if (!wdd)
 203                 return false;
 204
 205         if (watchdog_active(wdd))
 206                 return true;
 207
 208         return watchdog_hw_running(wdd) && !watchdog_past_open_deadline(wd_data);
 209 }
 210
 211 static void watchdog_ping_work(struct kthread_work *work)
 212 {
 213         struct watchdog_core_data *wd_data;
 214
 215         wd_data = container_of(work, struct watchdog_core_data, work);
 216
 217         mutex_lock(&wd_data->lock);
 218         if (watchdog_worker_should_ping(wd_data))
 219                 __watchdog_ping(wd_data->wdd);
 220         mutex_unlock(&wd_data->lock);
 221 }
 222
 223 static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer)
 224 {
 225         struct watchdog_core_data *wd_data;
 226
 227         wd_data = container_of(timer, struct watchdog_core_data, timer);
 228
 229         kthread_queue_work(watchdog_kworker, &wd_data->work);
 230         return HRTIMER_NORESTART;
 231 }
 232
 233 /*
 234  * watchdog_start - wrapper to start the watchdog
 235  * @wdd: The watchdog device to start
 236  *
 237  * Start the watchdog if it is not active and mark it active.
 238  * The caller must hold wd_data->lock.
 239  *
 240  * Return: 0 on success or a negative errno code for failure.
 241  */
 242 static int watchdog_start(struct watchdog_device *wdd)
 243 {
 244         struct watchdog_core_data *wd_data = wdd->wd_data;
 245         ktime_t started_at;
 246         int err;
 247
 248         if (watchdog_active(wdd))
 249                 return 0;
 250
 251         set_bit(_WDOG_KEEPALIVE, &wd_data->status);
 252
 253         started_at = ktime_get();
 254         if (watchdog_hw_running(wdd) && wdd->ops->ping) {
 255                 err = __watchdog_ping(wdd);
 256                 if (err == 0) {
 257                         set_bit(WDOG_ACTIVE, &wdd->status);
 258                         watchdog_hrtimer_pretimeout_start(wdd);
 259                 }
 260         } else {
 261                 err = wdd->ops->start(wdd);
 262                 if (err == 0) {
 263                         set_bit(WDOG_ACTIVE, &wdd->status);
 264                         wd_data->last_keepalive = started_at;
 265                         wd_data->last_hw_keepalive = started_at;
 266                         watchdog_update_worker(wdd);
 267                         watchdog_hrtimer_pretimeout_start(wdd);
 268                 }
 269         }
 270
 271         return err;
 272 }
 273
 274 /*
 275  * watchdog_stop - wrapper to stop the watchdog
 276  * @wdd: The watchdog device to stop
 277  *
 278  * Stop the watchdog if it is still active and unmark it active.
 279  * If the 'nowayout' feature was set, the watchdog cannot be stopped.
 280  * The caller must hold wd_data->lock.
 281  *
 282  * Return: 0 on success or a negative errno code for failure.
 283  */
 284 static int watchdog_stop(struct watchdog_device *wdd)
 285 {
 286         int err = 0;
 287
 288         if (!watchdog_active(wdd))
 289                 return 0;
 290
 291         if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
 292                 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
 293                         wdd->id);
 294                 return -EBUSY;
 295         }
 296
 297         if (wdd->ops->stop) {
 298                 clear_bit(WDOG_HW_RUNNING, &wdd->status);
 299                 err = wdd->ops->stop(wdd);
 300         } else {
 301                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 302         }
 303
 304         if (err == 0) {
 305                 clear_bit(WDOG_ACTIVE, &wdd->status);
 306                 watchdog_update_worker(wdd);
 307                 watchdog_hrtimer_pretimeout_stop(wdd);
 308         }
 309
 310         return err;
 311 }
 312
 313 /*
 314  * watchdog_get_status - wrapper to get the watchdog status
 315  * @wdd: The watchdog device to get the status from
 316  *
 317  * Get the watchdog's status flags.
 318  * The caller must hold wd_data->lock.
 319  *
 320  * Return: watchdog's status flags.
 321  */
 322 static unsigned int watchdog_get_status(struct watchdog_device *wdd)
 323 {
 324         struct watchdog_core_data *wd_data = wdd->wd_data;
 325         unsigned int status;
 326
 327         if (wdd->ops->status)
 328                 status = wdd->ops->status(wdd);
 329         else
 330                 status = wdd->bootstatus & (WDIOF_CARDRESET |
 331                                             WDIOF_OVERHEAT |
 332                                             WDIOF_FANFAULT |
 333                                             WDIOF_EXTERN1 |
 334                                             WDIOF_EXTERN2 |
 335                                             WDIOF_POWERUNDER |
 336                                             WDIOF_POWEROVER);
 337
 338         if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
 339                 status |= WDIOF_MAGICCLOSE;
 340
 341         if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
 342                 status |= WDIOF_KEEPALIVEPING;
 343
 344         if (IS_ENABLED(CONFIG_WATCHDOG_HRTIMER_PRETIMEOUT))
 345                 status |= WDIOF_PRETIMEOUT;
 346
 347         return status;
 348 }
 349
 350 /*
 351  * watchdog_set_timeout - set the watchdog timer timeout
 352  * @wdd:        The watchdog device to set the timeout for
 353  * @timeout:    Timeout to set in seconds
 354  *
 355  * The caller must hold wd_data->lock.
 356  *
 357  * Return: 0 if successful, error otherwise.
 358  */
 359 static int watchdog_set_timeout(struct watchdog_device *wdd,
 360                                                         unsigned int timeout)
 361 {
 362         int err = 0;
 363
 364         if (!(wdd->info->options & WDIOF_SETTIMEOUT))
 365                 return -EOPNOTSUPP;
 366
 367         if (watchdog_timeout_invalid(wdd, timeout))
 368                 return -EINVAL;
 369
 370         if (wdd->ops->set_timeout) {
 371                 err = wdd->ops->set_timeout(wdd, timeout);
 372         } else {
 373                 wdd->timeout = timeout;
 374                 /* Disable pretimeout if it doesn't fit the new timeout */
 375                 if (wdd->pretimeout >= wdd->timeout)
 376                         wdd->pretimeout = 0;
 377         }
 378
 379         watchdog_update_worker(wdd);
 380
 381         return err;
 382 }
 383
 384 /*
 385  * watchdog_set_pretimeout - set the watchdog timer pretimeout
 386  * @wdd:        The watchdog device to set the timeout for
 387  * @timeout:    pretimeout to set in seconds
 388  *
 389  * Return: 0 if successful, error otherwise.
 390  */
 391 static int watchdog_set_pretimeout(struct watchdog_device *wdd,
 392                                    unsigned int timeout)
 393 {
 394         int err = 0;
 395
 396         if (!watchdog_have_pretimeout(wdd))
 397                 return -EOPNOTSUPP;
 398
 399         if (watchdog_pretimeout_invalid(wdd, timeout))
 400                 return -EINVAL;
 401
 402         if (wdd->ops->set_pretimeout && (wdd->info->options & WDIOF_PRETIMEOUT))
 403                 err = wdd->ops->set_pretimeout(wdd, timeout);
 404         else
 405                 wdd->pretimeout = timeout;
 406
 407         return err;
 408 }
 409
 410 /*
 411  * watchdog_get_timeleft - wrapper to get the time left before a reboot
 412  * @wdd:        The watchdog device to get the remaining time from
 413  * @timeleft:   The time that's left
 414  *
 415  * Get the time before a watchdog will reboot (if not pinged).
 416  * The caller must hold wd_data->lock.
 417  *
 418  * Return: 0 if successful, error otherwise.
 419  */
 420 static int watchdog_get_timeleft(struct watchdog_device *wdd,
 421                                                         unsigned int *timeleft)
 422 {
 423         *timeleft = 0;
 424
 425         if (!wdd->ops->get_timeleft)
 426                 return -EOPNOTSUPP;
 427
 428         *timeleft = wdd->ops->get_timeleft(wdd);
 429
 430         return 0;
 431 }
 432
 433 #ifdef CONFIG_WATCHDOG_SYSFS
 434 static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
 435                                 char *buf)
 436 {
 437         struct watchdog_device *wdd = dev_get_drvdata(dev);
 438
 439         return sysfs_emit(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT,
 440                                                   &wdd->status));
 441 }
 442
 443 static ssize_t nowayout_store(struct device *dev, struct device_attribute *attr,
 444                                 const char *buf, size_t len)
 445 {
 446         struct watchdog_device *wdd = dev_get_drvdata(dev);
 447         unsigned int value;
 448         int ret;
 449
 450         ret = kstrtouint(buf, 0, &value);
 451         if (ret)
 452                 return ret;
 453         if (value > 1)
 454                 return -EINVAL;
 455         /* nowayout cannot be disabled once set */
 456         if (test_bit(WDOG_NO_WAY_OUT, &wdd->status) && !value)
 457                 return -EPERM;
 458         watchdog_set_nowayout(wdd, value);
 459         return len;
 460 }
 461 static DEVICE_ATTR_RW(nowayout);
 462
 463 static ssize_t status_show(struct device *dev, struct device_attribute *attr,
 464                                 char *buf)
 465 {
 466         struct watchdog_device *wdd = dev_get_drvdata(dev);
 467         struct watchdog_core_data *wd_data = wdd->wd_data;
 468         unsigned int status;
 469
 470         mutex_lock(&wd_data->lock);
 471         status = watchdog_get_status(wdd);
 472         mutex_unlock(&wd_data->lock);
 473
 474         return sysfs_emit(buf, "0x%x\n", status);
 475 }
 476 static DEVICE_ATTR_RO(status);
 477
 478 static ssize_t bootstatus_show(struct device *dev,
 479                                 struct device_attribute *attr, char *buf)
 480 {
 481         struct watchdog_device *wdd = dev_get_drvdata(dev);
 482
 483         return sysfs_emit(buf, "%u\n", wdd->bootstatus);
 484 }
 485 static DEVICE_ATTR_RO(bootstatus);
 486
 487 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
 488                                 char *buf)
 489 {
 490         struct watchdog_device *wdd = dev_get_drvdata(dev);
 491         struct watchdog_core_data *wd_data = wdd->wd_data;
 492         ssize_t status;
 493         unsigned int val;
 494
 495         mutex_lock(&wd_data->lock);
 496         status = watchdog_get_timeleft(wdd, &val);
 497         mutex_unlock(&wd_data->lock);
 498         if (!status)
 499                 status = sysfs_emit(buf, "%u\n", val);
 500
 501         return status;
 502 }
 503 static DEVICE_ATTR_RO(timeleft);
 504
 505 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
 506                                 char *buf)
 507 {
 508         struct watchdog_device *wdd = dev_get_drvdata(dev);
 509
 510         return sysfs_emit(buf, "%u\n", wdd->timeout);
 511 }
 512 static DEVICE_ATTR_RO(timeout);
 513
 514 static ssize_t min_timeout_show(struct device *dev,
 515                                 struct device_attribute *attr, char *buf)
 516 {
 517         struct watchdog_device *wdd = dev_get_drvdata(dev);
 518
 519         return sysfs_emit(buf, "%u\n", wdd->min_timeout);
 520 }
 521 static DEVICE_ATTR_RO(min_timeout);
 522
 523 static ssize_t max_timeout_show(struct device *dev,
 524                                 struct device_attribute *attr, char *buf)
 525 {
 526         struct watchdog_device *wdd = dev_get_drvdata(dev);
 527
 528         return sysfs_emit(buf, "%u\n", wdd->max_timeout);
 529 }
 530 static DEVICE_ATTR_RO(max_timeout);
 531
 532 static ssize_t pretimeout_show(struct device *dev,
 533                                struct device_attribute *attr, char *buf)
 534 {
 535         struct watchdog_device *wdd = dev_get_drvdata(dev);
 536
 537         return sysfs_emit(buf, "%u\n", wdd->pretimeout);
 538 }
 539 static DEVICE_ATTR_RO(pretimeout);
 540
 541 static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
 542                                 char *buf)
 543 {
 544         struct watchdog_device *wdd = dev_get_drvdata(dev);
 545
 546         return sysfs_emit(buf, "%s\n", wdd->info->identity);
 547 }
 548 static DEVICE_ATTR_RO(identity);
 549
 550 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
 551                                 char *buf)
 552 {
 553         struct watchdog_device *wdd = dev_get_drvdata(dev);
 554
 555         if (watchdog_active(wdd))
 556                 return sysfs_emit(buf, "active\n");
 557
 558         return sysfs_emit(buf, "inactive\n");
 559 }
 560 static DEVICE_ATTR_RO(state);
 561
 562 static ssize_t pretimeout_available_governors_show(struct device *dev,
 563                                    struct device_attribute *attr, char *buf)
 564 {
 565         return watchdog_pretimeout_available_governors_get(buf);
 566 }
 567 static DEVICE_ATTR_RO(pretimeout_available_governors);
 568
 569 static ssize_t pretimeout_governor_show(struct device *dev,
 570                                         struct device_attribute *attr,
 571                                         char *buf)
 572 {
 573         struct watchdog_device *wdd = dev_get_drvdata(dev);
 574
 575         return watchdog_pretimeout_governor_get(wdd, buf);
 576 }
 577
 578 static ssize_t pretimeout_governor_store(struct device *dev,
 579                                          struct device_attribute *attr,
 580                                          const char *buf, size_t count)
 581 {
 582         struct watchdog_device *wdd = dev_get_drvdata(dev);
 583         int ret = watchdog_pretimeout_governor_set(wdd, buf);
 584
 585         if (!ret)
 586                 ret = count;
 587
 588         return ret;
 589 }
 590 static DEVICE_ATTR_RW(pretimeout_governor);
 591
 592 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
 593                                 int n)
 594 {
 595         struct device *dev = kobj_to_dev(kobj);
 596         struct watchdog_device *wdd = dev_get_drvdata(dev);
 597         umode_t mode = attr->mode;
 598
 599         if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
 600                 mode = 0;
 601         else if (attr == &dev_attr_pretimeout.attr && !watchdog_have_pretimeout(wdd))
 602                 mode = 0;
 603         else if ((attr == &dev_attr_pretimeout_governor.attr ||
 604                   attr == &dev_attr_pretimeout_available_governors.attr) &&
 605                  (!watchdog_have_pretimeout(wdd) || !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
 606                 mode = 0;
 607
 608         return mode;
 609 }
 610 static struct attribute *wdt_attrs[] = {
 611         &dev_attr_state.attr,
 612         &dev_attr_identity.attr,
 613         &dev_attr_timeout.attr,
 614         &dev_attr_min_timeout.attr,
 615         &dev_attr_max_timeout.attr,
 616         &dev_attr_pretimeout.attr,
 617         &dev_attr_timeleft.attr,
 618         &dev_attr_bootstatus.attr,
 619         &dev_attr_status.attr,
 620         &dev_attr_nowayout.attr,
 621         &dev_attr_pretimeout_governor.attr,
 622         &dev_attr_pretimeout_available_governors.attr,
 623         NULL,
 624 };
 625
 626 static const struct attribute_group wdt_group = {
 627         .attrs = wdt_attrs,
 628         .is_visible = wdt_is_visible,
 629 };
 630 __ATTRIBUTE_GROUPS(wdt);
 631 #else
 632 #define wdt_groups      NULL
 633 #endif
 634
 635 /*
 636  * watchdog_ioctl_op - call the watchdog drivers ioctl op if defined
 637  * @wdd: The watchdog device to do the ioctl on
 638  * @cmd: Watchdog command
 639  * @arg: Argument pointer
 640  *
 641  * The caller must hold wd_data->lock.
 642  *
 643  * Return: 0 if successful, error otherwise.
 644  */
 645 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
 646                                                         unsigned long arg)
 647 {
 648         if (!wdd->ops->ioctl)
 649                 return -ENOIOCTLCMD;
 650
 651         return wdd->ops->ioctl(wdd, cmd, arg);
 652 }
 653
 654 /*
 655  * watchdog_write - writes to the watchdog
 656  * @file:       File from VFS
 657  * @data:       User address of data
 658  * @len:        Length of data
 659  * @ppos:       Pointer to the file offset
 660  *
 661  * A write to a watchdog device is defined as a keepalive ping.
 662  * Writing the magic 'V' sequence allows the next close to turn
 663  * off the watchdog (if 'nowayout' is not set).
 664  *
 665  * Return: @len if successful, error otherwise.
 666  */
 667 static ssize_t watchdog_write(struct file *file, const char __user *data,
 668                                                 size_t len, loff_t *ppos)
 669 {
 670         struct watchdog_core_data *wd_data = file->private_data;
 671         struct watchdog_device *wdd;
 672         int err;
 673         size_t i;
 674         char c;
 675
 676         if (len == 0)
 677                 return 0;
 678
 679         /*
 680          * Note: just in case someone wrote the magic character
 681          * five months ago...
 682          */
 683         clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
 684
 685         /* scan to see whether or not we got the magic character */
 686         for (i = 0; i != len; i++) {
 687                 if (get_user(c, data + i))
 688                         return -EFAULT;
 689                 if (c == 'V')
 690                         set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
 691         }
 692
 693         /* someone wrote to us, so we send the watchdog a keepalive ping */
 694
 695         err = -ENODEV;
 696         mutex_lock(&wd_data->lock);
 697         wdd = wd_data->wdd;
 698         if (wdd)
 699                 err = watchdog_ping(wdd);
 700         mutex_unlock(&wd_data->lock);
 701
 702         if (err < 0)
 703                 return err;
 704
 705         return len;
 706 }
 707
 708 /*
 709  * watchdog_ioctl - handle the different ioctl's for the watchdog device
 710  * @file:       File handle to the device
 711  * @cmd:        Watchdog command
 712  * @arg:        Argument pointer
 713  *
 714  * The watchdog API defines a common set of functions for all watchdogs
 715  * according to their available features.
 716  *
 717  * Return: 0 if successful, error otherwise.
 718  */
 719
 720 static long watchdog_ioctl(struct file *file, unsigned int cmd,
 721                                                         unsigned long arg)
 722 {
 723         struct watchdog_core_data *wd_data = file->private_data;
 724         void __user *argp = (void __user *)arg;
 725         struct watchdog_device *wdd;
 726         int __user *p = argp;
 727         unsigned int val;
 728         int err;
 729
 730         mutex_lock(&wd_data->lock);
 731
 732         wdd = wd_data->wdd;
 733         if (!wdd) {
 734                 err = -ENODEV;
 735                 goto out_ioctl;
 736         }
 737
 738         err = watchdog_ioctl_op(wdd, cmd, arg);
 739         if (err != -ENOIOCTLCMD)
 740                 goto out_ioctl;
 741
 742         switch (cmd) {
 743         case WDIOC_GETSUPPORT:
 744                 err = copy_to_user(argp, wdd->info,
 745                         sizeof(struct watchdog_info)) ? -EFAULT : 0;
 746                 break;
 747         case WDIOC_GETSTATUS:
 748                 val = watchdog_get_status(wdd);
 749                 err = put_user(val, p);
 750                 break;
 751         case WDIOC_GETBOOTSTATUS:
 752                 err = put_user(wdd->bootstatus, p);
 753                 break;
 754         case WDIOC_SETOPTIONS:
 755                 if (get_user(val, p)) {
 756                         err = -EFAULT;
 757                         break;
 758                 }
 759                 if (val & WDIOS_DISABLECARD) {
 760                         err = watchdog_stop(wdd);
 761                         if (err < 0)
 762                                 break;
 763                 }
 764                 if (val & WDIOS_ENABLECARD)
 765                         err = watchdog_start(wdd);
 766                 break;
 767         case WDIOC_KEEPALIVE:
 768                 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
 769                         err = -EOPNOTSUPP;
 770                         break;
 771                 }
 772                 err = watchdog_ping(wdd);
 773                 break;
 774         case WDIOC_SETTIMEOUT:
 775                 if (get_user(val, p)) {
 776                         err = -EFAULT;
 777                         break;
 778                 }
 779                 err = watchdog_set_timeout(wdd, val);
 780                 if (err < 0)
 781                         break;
 782                 /* If the watchdog is active then we send a keepalive ping
 783                  * to make sure that the watchdog keep's running (and if
 784                  * possible that it takes the new timeout) */
 785                 err = watchdog_ping(wdd);
 786                 if (err < 0)
 787                         break;
 788                 fallthrough;
 789         case WDIOC_GETTIMEOUT:
 790                 /* timeout == 0 means that we don't know the timeout */
 791                 if (wdd->timeout == 0) {
 792                         err = -EOPNOTSUPP;
 793                         break;
 794                 }
 795                 err = put_user(wdd->timeout, p);
 796                 break;
 797         case WDIOC_GETTIMELEFT:
 798                 err = watchdog_get_timeleft(wdd, &val);
 799                 if (err < 0)
 800                         break;
 801                 err = put_user(val, p);
 802                 break;
 803         case WDIOC_SETPRETIMEOUT:
 804                 if (get_user(val, p)) {
 805                         err = -EFAULT;
 806                         break;
 807                 }
 808                 err = watchdog_set_pretimeout(wdd, val);
 809                 break;
 810         case WDIOC_GETPRETIMEOUT:
 811                 err = put_user(wdd->pretimeout, p);
 812                 break;
 813         default:
 814                 err = -ENOTTY;
 815                 break;
 816         }
 817
 818 out_ioctl:
 819         mutex_unlock(&wd_data->lock);
 820         return err;
 821 }
 822
 823 /*
 824  * watchdog_open - open the /dev/watchdog* devices
 825  * @inode:      Inode of device
 826  * @file:       File handle to device
 827  *
 828  * When the /dev/watchdog* device gets opened, we start the watchdog.
 829  * Watch out: the /dev/watchdog device is single open, so we make sure
 830  * it can only be opened once.
 831  *
 832  * Return: 0 if successful, error otherwise.
 833  */
 834 static int watchdog_open(struct inode *inode, struct file *file)
 835 {
 836         struct watchdog_core_data *wd_data;
 837         struct watchdog_device *wdd;
 838         bool hw_running;
 839         int err;
 840
 841         /* Get the corresponding watchdog device */
 842         if (imajor(inode) == MISC_MAJOR)
 843                 wd_data = old_wd_data;
 844         else
 845                 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
 846                                        cdev);
 847
 848         /* the watchdog is single open! */
 849         if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
 850                 return -EBUSY;
 851
 852         wdd = wd_data->wdd;
 853
 854         /*
 855          * If the /dev/watchdog device is open, we don't want the module
 856          * to be unloaded.
 857          */
 858         hw_running = watchdog_hw_running(wdd);
 859         if (!hw_running && !try_module_get(wdd->ops->owner)) {
 860                 err = -EBUSY;
 861                 goto out_clear;
 862         }
 863
 864         err = watchdog_start(wdd);
 865         if (err < 0)
 866                 goto out_mod;
 867
 868         file->private_data = wd_data;
 869
 870         if (!hw_running)
 871                 get_device(&wd_data->dev);
 872
 873         /*
 874          * open_timeout only applies for the first open from
 875          * userspace. Set open_deadline to infinity so that the kernel
 876          * will take care of an always-running hardware watchdog in
 877          * case the device gets magic-closed or WDIOS_DISABLECARD is
 878          * applied.
 879          */
 880         wd_data->open_deadline = KTIME_MAX;
 881
 882         /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
 883         return stream_open(inode, file);
 884
 885 out_mod:
 886         module_put(wd_data->wdd->ops->owner);
 887 out_clear:
 888         clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
 889         return err;
 890 }
 891
 892 static void watchdog_core_data_release(struct device *dev)
 893 {
 894         struct watchdog_core_data *wd_data;
 895
 896         wd_data = container_of(dev, struct watchdog_core_data, dev);
 897
 898         kfree(wd_data);
 899 }
 900
 901 /*
 902  * watchdog_release - release the watchdog device
 903  * @inode:      Inode of device
 904  * @file:       File handle to device
 905  *
 906  * This is the code for when /dev/watchdog gets closed. We will only
 907  * stop the watchdog when we have received the magic char (and nowayout
 908  * was not set), else the watchdog will keep running.
 909  *
 910  * Always returns 0.
 911  */
 912 static int watchdog_release(struct inode *inode, struct file *file)
 913 {
 914         struct watchdog_core_data *wd_data = file->private_data;
 915         struct watchdog_device *wdd;
 916         int err = -EBUSY;
 917         bool running;
 918
 919         mutex_lock(&wd_data->lock);
 920
 921         wdd = wd_data->wdd;
 922         if (!wdd)
 923                 goto done;
 924
 925         /*
 926          * We only stop the watchdog if we received the magic character
 927          * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
 928          * watchdog_stop will fail.
 929          */
 930         if (!watchdog_active(wdd))
 931                 err = 0;
 932         else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
 933                  !(wdd->info->options & WDIOF_MAGICCLOSE))
 934                 err = watchdog_stop(wdd);
 935
 936         /* If the watchdog was not stopped, send a keepalive ping */
 937         if (err < 0) {
 938                 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
 939                 watchdog_ping(wdd);
 940         }
 941
 942         watchdog_update_worker(wdd);
 943
 944         /* make sure that /dev/watchdog can be re-opened */
 945         clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
 946
 947 done:
 948         running = wdd && watchdog_hw_running(wdd);
 949         mutex_unlock(&wd_data->lock);
 950         /*
 951          * Allow the owner module to be unloaded again unless the watchdog
 952          * is still running. If the watchdog is still running, it can not
 953          * be stopped, and its driver must not be unloaded.
 954          */
 955         if (!running) {
 956                 module_put(wd_data->cdev.owner);
 957                 put_device(&wd_data->dev);
 958         }
 959         return 0;
 960 }
 961
 962 static const struct file_operations watchdog_fops = {
 963         .owner          = THIS_MODULE,
 964         .write          = watchdog_write,
 965         .unlocked_ioctl = watchdog_ioctl,
 966         .compat_ioctl   = compat_ptr_ioctl,
 967         .open           = watchdog_open,
 968         .release        = watchdog_release,
 969 };
 970
 971 static struct miscdevice watchdog_miscdev = {
 972         .minor          = WATCHDOG_MINOR,
 973         .name           = "watchdog",
 974         .fops           = &watchdog_fops,
 975 };
 976
 977 static struct class watchdog_class = {
 978         .name =         "watchdog",
 979         .owner =        THIS_MODULE,
 980         .dev_groups =   wdt_groups,
 981 };
 982
 983 /*
 984  * watchdog_cdev_register - register watchdog character device
 985  * @wdd: Watchdog device
 986  *
 987  * Register a watchdog character device including handling the legacy
 988  * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
 989  * thus we set it up like that.
 990  *
 991  * Return: 0 if successful, error otherwise.
 992  */
 993 static int watchdog_cdev_register(struct watchdog_device *wdd)
 994 {
 995         struct watchdog_core_data *wd_data;
 996         int err;
 997
 998         wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
 999         if (!wd_data)
1000                 return -ENOMEM;
1001         mutex_init(&wd_data->lock);
1002
1003         wd_data->wdd = wdd;
1004         wdd->wd_data = wd_data;
1005
1006         if (IS_ERR_OR_NULL(watchdog_kworker)) {
1007                 kfree(wd_data);
1008                 return -ENODEV;
1009         }
1010
1011         device_initialize(&wd_data->dev);
1012         wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id);
1013         wd_data->dev.class = &watchdog_class;
1014         wd_data->dev.parent = wdd->parent;
1015         wd_data->dev.groups = wdd->groups;
1016         wd_data->dev.release = watchdog_core_data_release;
1017         dev_set_drvdata(&wd_data->dev, wdd);
1018         dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);
1019
1020         kthread_init_work(&wd_data->work, watchdog_ping_work);
1021         hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
1022         wd_data->timer.function = watchdog_timer_expired;
1023         watchdog_hrtimer_pretimeout_init(wdd);
1024
1025         if (wdd->id == 0) {
1026                 old_wd_data = wd_data;
1027                 watchdog_miscdev.parent = wdd->parent;
1028                 err = misc_register(&watchdog_miscdev);
1029                 if (err != 0) {
1030                         pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
1031                                 wdd->info->identity, WATCHDOG_MINOR, err);
1032                         if (err == -EBUSY)
1033                                 pr_err("%s: a legacy watchdog module is probably present.\n",
1034                                         wdd->info->identity);
1035                         old_wd_data = NULL;
1036                         put_device(&wd_data->dev);
1037                         return err;
1038                 }
1039         }
1040
1041         /* Fill in the data structures */
1042         cdev_init(&wd_data->cdev, &watchdog_fops);
1043
1044         /* Add the device */
1045         err = cdev_device_add(&wd_data->cdev, &wd_data->dev);
1046         if (err) {
1047                 pr_err("watchdog%d unable to add device %d:%d\n",
1048                         wdd->id,  MAJOR(watchdog_devt), wdd->id);
1049                 if (wdd->id == 0) {
1050                         misc_deregister(&watchdog_miscdev);
1051                         old_wd_data = NULL;
1052                         put_device(&wd_data->dev);
1053                 }
1054                 return err;
1055         }
1056
1057         wd_data->cdev.owner = wdd->ops->owner;
1058
1059         /* Record time of most recent heartbeat as 'just before now'. */
1060         wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1);
1061         watchdog_set_open_deadline(wd_data);
1062
1063         /*
1064          * If the watchdog is running, prevent its driver from being unloaded,
1065          * and schedule an immediate ping.
1066          */
1067         if (watchdog_hw_running(wdd)) {
1068                 __module_get(wdd->ops->owner);
1069                 get_device(&wd_data->dev);
1070                 if (handle_boot_enabled)
1071                         hrtimer_start(&wd_data->timer, 0,
1072                                       HRTIMER_MODE_REL_HARD);
1073                 else
1074                         pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
1075                                 wdd->id);
1076         }
1077
1078         return 0;
1079 }
1080
1081 /*
1082  * watchdog_cdev_unregister - unregister watchdog character device
1083  * @wdd: Watchdog device
1084  *
1085  * Unregister watchdog character device and if needed the legacy
1086  * /dev/watchdog device.
1087  */
1088 static void watchdog_cdev_unregister(struct watchdog_device *wdd)
1089 {
1090         struct watchdog_core_data *wd_data = wdd->wd_data;
1091
1092         cdev_device_del(&wd_data->cdev, &wd_data->dev);
1093         if (wdd->id == 0) {
1094                 misc_deregister(&watchdog_miscdev);
1095                 old_wd_data = NULL;
1096         }
1097
1098         if (watchdog_active(wdd) &&
1099             test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
1100                 watchdog_stop(wdd);
1101         }
1102
1103         watchdog_hrtimer_pretimeout_stop(wdd);
1104
1105         mutex_lock(&wd_data->lock);
1106         wd_data->wdd = NULL;
1107         wdd->wd_data = NULL;
1108         mutex_unlock(&wd_data->lock);
1109
1110         hrtimer_cancel(&wd_data->timer);
1111         kthread_cancel_work_sync(&wd_data->work);
1112
1113         put_device(&wd_data->dev);
1114 }
1115
1116 /**
1117  * watchdog_dev_register - register a watchdog device
1118  * @wdd: Watchdog device
1119  *
1120  * Register a watchdog device including handling the legacy
1121  * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1122  * thus we set it up like that.
1123  *
1124  * Return: 0 if successful, error otherwise.
1125  */
1126 int watchdog_dev_register(struct watchdog_device *wdd)
1127 {
1128         int ret;
1129
1130         ret = watchdog_cdev_register(wdd);
1131         if (ret)
1132                 return ret;
1133
1134         ret = watchdog_register_pretimeout(wdd);
1135         if (ret)
1136                 watchdog_cdev_unregister(wdd);
1137
1138         return ret;
1139 }
1140
1141 /**
1142  * watchdog_dev_unregister - unregister a watchdog device
1143  * @wdd: watchdog device
1144  *
1145  * Unregister watchdog device and if needed the legacy
1146  * /dev/watchdog device.
1147  */
1148 void watchdog_dev_unregister(struct watchdog_device *wdd)
1149 {
1150         watchdog_unregister_pretimeout(wdd);
1151         watchdog_cdev_unregister(wdd);
1152 }
1153
1154 /**
1155  * watchdog_set_last_hw_keepalive - set last HW keepalive time for watchdog
1156  * @wdd:                Watchdog device
1157  * @last_ping_ms:       Time since last HW heartbeat
1158  *
1159  * Adjusts the last known HW keepalive time for a watchdog timer.
1160  * This is needed if the watchdog is already running when the probe
1161  * function is called, and it can't be pinged immediately. This
1162  * function must be called immediately after watchdog registration,
1163  * and min_hw_heartbeat_ms must be set for this to be useful.
1164  *
1165  * Return: 0 if successful, error otherwise.
1166  */
1167 int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,
1168                                    unsigned int last_ping_ms)
1169 {
1170         struct watchdog_core_data *wd_data;
1171         ktime_t now;
1172
1173         if (!wdd)
1174                 return -EINVAL;
1175
1176         wd_data = wdd->wd_data;
1177
1178         now = ktime_get();
1179
1180         wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms));
1181
1182         if (watchdog_hw_running(wdd) && handle_boot_enabled)
1183                 return __watchdog_ping(wdd);
1184
1185         return 0;
1186 }
1187 EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive);
1188
1189 /**
1190  * watchdog_dev_init - init dev part of watchdog core
1191  *
1192  * Allocate a range of chardev nodes to use for watchdog devices.
1193  *
1194  * Return: 0 if successful, error otherwise.
1195  */
1196 int __init watchdog_dev_init(void)
1197 {
1198         int err;
1199
1200         watchdog_kworker = kthread_create_worker(0, "watchdogd");
1201         if (IS_ERR(watchdog_kworker)) {
1202                 pr_err("Failed to create watchdog kworker\n");
1203                 return PTR_ERR(watchdog_kworker);
1204         }
1205         sched_set_fifo(watchdog_kworker->task);
1206
1207         err = class_register(&watchdog_class);
1208         if (err < 0) {
1209                 pr_err("couldn't register class\n");
1210                 goto err_register;
1211         }
1212
1213         err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
1214         if (err < 0) {
1215                 pr_err("watchdog: unable to allocate char dev region\n");
1216                 goto err_alloc;
1217         }
1218
1219         return 0;
1220
1221 err_alloc:
1222         class_unregister(&watchdog_class);
1223 err_register:
1224         kthread_destroy_worker(watchdog_kworker);
1225         return err;
1226 }
1227
1228 /**
1229  * watchdog_dev_exit - exit dev part of watchdog core
1230  *
1231  * Release the range of chardev nodes used for watchdog devices.
1232  */
1233 void __exit watchdog_dev_exit(void)
1234 {
1235         unregister_chrdev_region(watchdog_devt, MAX_DOGS);
1236         class_unregister(&watchdog_class);
1237         kthread_destroy_worker(watchdog_kworker);
1238 }
1239
1240 int watchdog_dev_suspend(struct watchdog_device *wdd)
1241 {
1242         struct watchdog_core_data *wd_data = wdd->wd_data;
1243         int ret = 0;
1244
1245         if (!wdd->wd_data)
1246                 return -ENODEV;
1247
1248         /* ping for the last time before suspend */
1249         mutex_lock(&wd_data->lock);
1250         if (watchdog_worker_should_ping(wd_data))
1251                 ret = __watchdog_ping(wd_data->wdd);
1252         mutex_unlock(&wd_data->lock);
1253
1254         if (ret)
1255                 return ret;
1256
1257         /*
1258          * make sure that watchdog worker will not kick in when the wdog is
1259          * suspended
1260          */
1261         hrtimer_cancel(&wd_data->timer);
1262         kthread_cancel_work_sync(&wd_data->work);
1263
1264         return 0;
1265 }
1266
1267 int watchdog_dev_resume(struct watchdog_device *wdd)
1268 {
1269         struct watchdog_core_data *wd_data = wdd->wd_data;
1270         int ret = 0;
1271
1272         if (!wdd->wd_data)
1273                 return -ENODEV;
1274
1275         /*
1276          * __watchdog_ping will also retrigger hrtimer and therefore restore the
1277          * ping worker if needed.
1278          */
1279         mutex_lock(&wd_data->lock);
1280         if (watchdog_worker_should_ping(wd_data))
1281                 ret = __watchdog_ping(wd_data->wdd);
1282         mutex_unlock(&wd_data->lock);
1283
1284         return ret;
1285 }
1286
1287 module_param(handle_boot_enabled, bool, 0444);
1288 MODULE_PARM_DESC(handle_boot_enabled,
1289         "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1290         __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");
1291
1292 module_param(open_timeout, uint, 0644);
1293 MODULE_PARM_DESC(open_timeout,
1294         "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default="
1295         __MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")");