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