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 sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status)); 455 } 456 457 static ssize_t nowayout_store(struct device *dev, struct device_attribute *attr, 458 const char *buf, size_t len) 459 { 460 struct watchdog_device *wdd = dev_get_drvdata(dev); 461 unsigned int value; 462 int ret; 463 464 ret = kstrtouint(buf, 0, &value); 465 if (ret) 466 return ret; 467 if (value > 1) 468 return -EINVAL; 469 /* nowayout cannot be disabled once set */ 470 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status) && !value) 471 return -EPERM; 472 watchdog_set_nowayout(wdd, value); 473 return len; 474 } 475 static DEVICE_ATTR_RW(nowayout); 476 477 static ssize_t status_show(struct device *dev, struct device_attribute *attr, 478 char *buf) 479 { 480 struct watchdog_device *wdd = dev_get_drvdata(dev); 481 struct watchdog_core_data *wd_data = wdd->wd_data; 482 unsigned int status; 483 484 mutex_lock(&wd_data->lock); 485 status = watchdog_get_status(wdd); 486 mutex_unlock(&wd_data->lock); 487 488 return sprintf(buf, "0x%x\n", status); 489 } 490 static DEVICE_ATTR_RO(status); 491 492 static ssize_t bootstatus_show(struct device *dev, 493 struct device_attribute *attr, char *buf) 494 { 495 struct watchdog_device *wdd = dev_get_drvdata(dev); 496 497 return sprintf(buf, "%u\n", wdd->bootstatus); 498 } 499 static DEVICE_ATTR_RO(bootstatus); 500 501 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr, 502 char *buf) 503 { 504 struct watchdog_device *wdd = dev_get_drvdata(dev); 505 struct watchdog_core_data *wd_data = wdd->wd_data; 506 ssize_t status; 507 unsigned int val; 508 509 mutex_lock(&wd_data->lock); 510 status = watchdog_get_timeleft(wdd, &val); 511 mutex_unlock(&wd_data->lock); 512 if (!status) 513 status = sprintf(buf, "%u\n", val); 514 515 return status; 516 } 517 static DEVICE_ATTR_RO(timeleft); 518 519 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr, 520 char *buf) 521 { 522 struct watchdog_device *wdd = dev_get_drvdata(dev); 523 524 return sprintf(buf, "%u\n", wdd->timeout); 525 } 526 static DEVICE_ATTR_RO(timeout); 527 528 static ssize_t min_timeout_show(struct device *dev, 529 struct device_attribute *attr, char *buf) 530 { 531 struct watchdog_device *wdd = dev_get_drvdata(dev); 532 533 return sysfs_emit(buf, "%u\n", wdd->min_timeout); 534 } 535 static DEVICE_ATTR_RO(min_timeout); 536 537 static ssize_t max_timeout_show(struct device *dev, 538 struct device_attribute *attr, char *buf) 539 { 540 struct watchdog_device *wdd = dev_get_drvdata(dev); 541 542 return sysfs_emit(buf, "%u\n", wdd->max_timeout); 543 } 544 static DEVICE_ATTR_RO(max_timeout); 545 546 static ssize_t pretimeout_show(struct device *dev, 547 struct device_attribute *attr, char *buf) 548 { 549 struct watchdog_device *wdd = dev_get_drvdata(dev); 550 551 return sprintf(buf, "%u\n", wdd->pretimeout); 552 } 553 static DEVICE_ATTR_RO(pretimeout); 554 555 static ssize_t identity_show(struct device *dev, struct device_attribute *attr, 556 char *buf) 557 { 558 struct watchdog_device *wdd = dev_get_drvdata(dev); 559 560 return sprintf(buf, "%s\n", wdd->info->identity); 561 } 562 static DEVICE_ATTR_RO(identity); 563 564 static ssize_t state_show(struct device *dev, struct device_attribute *attr, 565 char *buf) 566 { 567 struct watchdog_device *wdd = dev_get_drvdata(dev); 568 569 if (watchdog_active(wdd)) 570 return sprintf(buf, "active\n"); 571 572 return sprintf(buf, "inactive\n"); 573 } 574 static DEVICE_ATTR_RO(state); 575 576 static ssize_t pretimeout_available_governors_show(struct device *dev, 577 struct device_attribute *attr, char *buf) 578 { 579 return watchdog_pretimeout_available_governors_get(buf); 580 } 581 static DEVICE_ATTR_RO(pretimeout_available_governors); 582 583 static ssize_t pretimeout_governor_show(struct device *dev, 584 struct device_attribute *attr, 585 char *buf) 586 { 587 struct watchdog_device *wdd = dev_get_drvdata(dev); 588 589 return watchdog_pretimeout_governor_get(wdd, buf); 590 } 591 592 static ssize_t pretimeout_governor_store(struct device *dev, 593 struct device_attribute *attr, 594 const char *buf, size_t count) 595 { 596 struct watchdog_device *wdd = dev_get_drvdata(dev); 597 int ret = watchdog_pretimeout_governor_set(wdd, buf); 598 599 if (!ret) 600 ret = count; 601 602 return ret; 603 } 604 static DEVICE_ATTR_RW(pretimeout_governor); 605 606 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr, 607 int n) 608 { 609 struct device *dev = kobj_to_dev(kobj); 610 struct watchdog_device *wdd = dev_get_drvdata(dev); 611 umode_t mode = attr->mode; 612 613 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft) 614 mode = 0; 615 else if (attr == &dev_attr_pretimeout.attr && 616 !(wdd->info->options & WDIOF_PRETIMEOUT)) 617 mode = 0; 618 else if ((attr == &dev_attr_pretimeout_governor.attr || 619 attr == &dev_attr_pretimeout_available_governors.attr) && 620 (!(wdd->info->options & WDIOF_PRETIMEOUT) || 621 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV))) 622 mode = 0; 623 624 return mode; 625 } 626 static struct attribute *wdt_attrs[] = { 627 &dev_attr_state.attr, 628 &dev_attr_identity.attr, 629 &dev_attr_timeout.attr, 630 &dev_attr_min_timeout.attr, 631 &dev_attr_max_timeout.attr, 632 &dev_attr_pretimeout.attr, 633 &dev_attr_timeleft.attr, 634 &dev_attr_bootstatus.attr, 635 &dev_attr_status.attr, 636 &dev_attr_nowayout.attr, 637 &dev_attr_pretimeout_governor.attr, 638 &dev_attr_pretimeout_available_governors.attr, 639 NULL, 640 }; 641 642 static const struct attribute_group wdt_group = { 643 .attrs = wdt_attrs, 644 .is_visible = wdt_is_visible, 645 }; 646 __ATTRIBUTE_GROUPS(wdt); 647 #else 648 #define wdt_groups NULL 649 #endif 650 651 /* 652 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined 653 * @wdd: the watchdog device to do the ioctl on 654 * @cmd: watchdog command 655 * @arg: argument pointer 656 * 657 * The caller must hold wd_data->lock. 658 */ 659 660 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd, 661 unsigned long arg) 662 { 663 if (!wdd->ops->ioctl) 664 return -ENOIOCTLCMD; 665 666 return wdd->ops->ioctl(wdd, cmd, arg); 667 } 668 669 /* 670 * watchdog_write: writes to the watchdog. 671 * @file: file from VFS 672 * @data: user address of data 673 * @len: length of data 674 * @ppos: pointer to the file offset 675 * 676 * A write to a watchdog device is defined as a keepalive ping. 677 * Writing the magic 'V' sequence allows the next close to turn 678 * off the watchdog (if 'nowayout' is not set). 679 */ 680 681 static ssize_t watchdog_write(struct file *file, const char __user *data, 682 size_t len, loff_t *ppos) 683 { 684 struct watchdog_core_data *wd_data = file->private_data; 685 struct watchdog_device *wdd; 686 int err; 687 size_t i; 688 char c; 689 690 if (len == 0) 691 return 0; 692 693 /* 694 * Note: just in case someone wrote the magic character 695 * five months ago... 696 */ 697 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status); 698 699 /* scan to see whether or not we got the magic character */ 700 for (i = 0; i != len; i++) { 701 if (get_user(c, data + i)) 702 return -EFAULT; 703 if (c == 'V') 704 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status); 705 } 706 707 /* someone wrote to us, so we send the watchdog a keepalive ping */ 708 709 err = -ENODEV; 710 mutex_lock(&wd_data->lock); 711 wdd = wd_data->wdd; 712 if (wdd) 713 err = watchdog_ping(wdd); 714 mutex_unlock(&wd_data->lock); 715 716 if (err < 0) 717 return err; 718 719 return len; 720 } 721 722 /* 723 * watchdog_ioctl: handle the different ioctl's for the watchdog device. 724 * @file: file handle to the device 725 * @cmd: watchdog command 726 * @arg: argument pointer 727 * 728 * The watchdog API defines a common set of functions for all watchdogs 729 * according to their available features. 730 */ 731 732 static long watchdog_ioctl(struct file *file, unsigned int cmd, 733 unsigned long arg) 734 { 735 struct watchdog_core_data *wd_data = file->private_data; 736 void __user *argp = (void __user *)arg; 737 struct watchdog_device *wdd; 738 int __user *p = argp; 739 unsigned int val; 740 int err; 741 742 mutex_lock(&wd_data->lock); 743 744 wdd = wd_data->wdd; 745 if (!wdd) { 746 err = -ENODEV; 747 goto out_ioctl; 748 } 749 750 err = watchdog_ioctl_op(wdd, cmd, arg); 751 if (err != -ENOIOCTLCMD) 752 goto out_ioctl; 753 754 switch (cmd) { 755 case WDIOC_GETSUPPORT: 756 err = copy_to_user(argp, wdd->info, 757 sizeof(struct watchdog_info)) ? -EFAULT : 0; 758 break; 759 case WDIOC_GETSTATUS: 760 val = watchdog_get_status(wdd); 761 err = put_user(val, p); 762 break; 763 case WDIOC_GETBOOTSTATUS: 764 err = put_user(wdd->bootstatus, p); 765 break; 766 case WDIOC_SETOPTIONS: 767 if (get_user(val, p)) { 768 err = -EFAULT; 769 break; 770 } 771 if (val & WDIOS_DISABLECARD) { 772 err = watchdog_stop(wdd); 773 if (err < 0) 774 break; 775 } 776 if (val & WDIOS_ENABLECARD) 777 err = watchdog_start(wdd); 778 break; 779 case WDIOC_KEEPALIVE: 780 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) { 781 err = -EOPNOTSUPP; 782 break; 783 } 784 err = watchdog_ping(wdd); 785 break; 786 case WDIOC_SETTIMEOUT: 787 if (get_user(val, p)) { 788 err = -EFAULT; 789 break; 790 } 791 err = watchdog_set_timeout(wdd, val); 792 if (err < 0) 793 break; 794 /* If the watchdog is active then we send a keepalive ping 795 * to make sure that the watchdog keep's running (and if 796 * possible that it takes the new timeout) */ 797 err = watchdog_ping(wdd); 798 if (err < 0) 799 break; 800 fallthrough; 801 case WDIOC_GETTIMEOUT: 802 /* timeout == 0 means that we don't know the timeout */ 803 if (wdd->timeout == 0) { 804 err = -EOPNOTSUPP; 805 break; 806 } 807 err = put_user(wdd->timeout, p); 808 break; 809 case WDIOC_GETTIMELEFT: 810 err = watchdog_get_timeleft(wdd, &val); 811 if (err < 0) 812 break; 813 err = put_user(val, p); 814 break; 815 case WDIOC_SETPRETIMEOUT: 816 if (get_user(val, p)) { 817 err = -EFAULT; 818 break; 819 } 820 err = watchdog_set_pretimeout(wdd, val); 821 break; 822 case WDIOC_GETPRETIMEOUT: 823 err = put_user(wdd->pretimeout, p); 824 break; 825 default: 826 err = -ENOTTY; 827 break; 828 } 829 830 out_ioctl: 831 mutex_unlock(&wd_data->lock); 832 return err; 833 } 834 835 /* 836 * watchdog_open: open the /dev/watchdog* devices. 837 * @inode: inode of device 838 * @file: file handle to device 839 * 840 * When the /dev/watchdog* device gets opened, we start the watchdog. 841 * Watch out: the /dev/watchdog device is single open, so we make sure 842 * it can only be opened once. 843 */ 844 845 static int watchdog_open(struct inode *inode, struct file *file) 846 { 847 struct watchdog_core_data *wd_data; 848 struct watchdog_device *wdd; 849 bool hw_running; 850 int err; 851 852 /* Get the corresponding watchdog device */ 853 if (imajor(inode) == MISC_MAJOR) 854 wd_data = old_wd_data; 855 else 856 wd_data = container_of(inode->i_cdev, struct watchdog_core_data, 857 cdev); 858 859 /* the watchdog is single open! */ 860 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status)) 861 return -EBUSY; 862 863 wdd = wd_data->wdd; 864 865 /* 866 * If the /dev/watchdog device is open, we don't want the module 867 * to be unloaded. 868 */ 869 hw_running = watchdog_hw_running(wdd); 870 if (!hw_running && !try_module_get(wdd->ops->owner)) { 871 err = -EBUSY; 872 goto out_clear; 873 } 874 875 err = watchdog_start(wdd); 876 if (err < 0) 877 goto out_mod; 878 879 file->private_data = wd_data; 880 881 if (!hw_running) 882 get_device(&wd_data->dev); 883 884 /* 885 * open_timeout only applies for the first open from 886 * userspace. Set open_deadline to infinity so that the kernel 887 * will take care of an always-running hardware watchdog in 888 * case the device gets magic-closed or WDIOS_DISABLECARD is 889 * applied. 890 */ 891 wd_data->open_deadline = KTIME_MAX; 892 893 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */ 894 return stream_open(inode, file); 895 896 out_mod: 897 module_put(wd_data->wdd->ops->owner); 898 out_clear: 899 clear_bit(_WDOG_DEV_OPEN, &wd_data->status); 900 return err; 901 } 902 903 static void watchdog_core_data_release(struct device *dev) 904 { 905 struct watchdog_core_data *wd_data; 906 907 wd_data = container_of(dev, struct watchdog_core_data, dev); 908 909 kfree(wd_data); 910 } 911 912 /* 913 * watchdog_release: release the watchdog device. 914 * @inode: inode of device 915 * @file: file handle to device 916 * 917 * This is the code for when /dev/watchdog gets closed. We will only 918 * stop the watchdog when we have received the magic char (and nowayout 919 * was not set), else the watchdog will keep running. 920 */ 921 922 static int watchdog_release(struct inode *inode, struct file *file) 923 { 924 struct watchdog_core_data *wd_data = file->private_data; 925 struct watchdog_device *wdd; 926 int err = -EBUSY; 927 bool running; 928 929 mutex_lock(&wd_data->lock); 930 931 wdd = wd_data->wdd; 932 if (!wdd) 933 goto done; 934 935 /* 936 * We only stop the watchdog if we received the magic character 937 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then 938 * watchdog_stop will fail. 939 */ 940 if (!watchdog_active(wdd)) 941 err = 0; 942 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) || 943 !(wdd->info->options & WDIOF_MAGICCLOSE)) 944 err = watchdog_stop(wdd); 945 946 /* If the watchdog was not stopped, send a keepalive ping */ 947 if (err < 0) { 948 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id); 949 watchdog_ping(wdd); 950 } 951 952 watchdog_update_worker(wdd); 953 954 /* make sure that /dev/watchdog can be re-opened */ 955 clear_bit(_WDOG_DEV_OPEN, &wd_data->status); 956 957 done: 958 running = wdd && watchdog_hw_running(wdd); 959 mutex_unlock(&wd_data->lock); 960 /* 961 * Allow the owner module to be unloaded again unless the watchdog 962 * is still running. If the watchdog is still running, it can not 963 * be stopped, and its driver must not be unloaded. 964 */ 965 if (!running) { 966 module_put(wd_data->cdev.owner); 967 put_device(&wd_data->dev); 968 } 969 return 0; 970 } 971 972 static const struct file_operations watchdog_fops = { 973 .owner = THIS_MODULE, 974 .write = watchdog_write, 975 .unlocked_ioctl = watchdog_ioctl, 976 .compat_ioctl = compat_ptr_ioctl, 977 .open = watchdog_open, 978 .release = watchdog_release, 979 }; 980 981 static struct miscdevice watchdog_miscdev = { 982 .minor = WATCHDOG_MINOR, 983 .name = "watchdog", 984 .fops = &watchdog_fops, 985 }; 986 987 static struct class watchdog_class = { 988 .name = "watchdog", 989 .owner = THIS_MODULE, 990 .dev_groups = wdt_groups, 991 }; 992 993 /* 994 * watchdog_cdev_register: register watchdog character device 995 * @wdd: watchdog device 996 * 997 * Register a watchdog character device including handling the legacy 998 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and 999 * thus we set it up like that. 1000 */ 1001 1002 static int watchdog_cdev_register(struct watchdog_device *wdd) 1003 { 1004 struct watchdog_core_data *wd_data; 1005 int err; 1006 1007 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL); 1008 if (!wd_data) 1009 return -ENOMEM; 1010 mutex_init(&wd_data->lock); 1011 1012 wd_data->wdd = wdd; 1013 wdd->wd_data = wd_data; 1014 1015 if (IS_ERR_OR_NULL(watchdog_kworker)) { 1016 kfree(wd_data); 1017 return -ENODEV; 1018 } 1019 1020 device_initialize(&wd_data->dev); 1021 wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id); 1022 wd_data->dev.class = &watchdog_class; 1023 wd_data->dev.parent = wdd->parent; 1024 wd_data->dev.groups = wdd->groups; 1025 wd_data->dev.release = watchdog_core_data_release; 1026 dev_set_drvdata(&wd_data->dev, wdd); 1027 dev_set_name(&wd_data->dev, "watchdog%d", wdd->id); 1028 1029 kthread_init_work(&wd_data->work, watchdog_ping_work); 1030 hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); 1031 wd_data->timer.function = watchdog_timer_expired; 1032 1033 if (wdd->id == 0) { 1034 old_wd_data = wd_data; 1035 watchdog_miscdev.parent = wdd->parent; 1036 err = misc_register(&watchdog_miscdev); 1037 if (err != 0) { 1038 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n", 1039 wdd->info->identity, WATCHDOG_MINOR, err); 1040 if (err == -EBUSY) 1041 pr_err("%s: a legacy watchdog module is probably present.\n", 1042 wdd->info->identity); 1043 old_wd_data = NULL; 1044 put_device(&wd_data->dev); 1045 return err; 1046 } 1047 } 1048 1049 /* Fill in the data structures */ 1050 cdev_init(&wd_data->cdev, &watchdog_fops); 1051 1052 /* Add the device */ 1053 err = cdev_device_add(&wd_data->cdev, &wd_data->dev); 1054 if (err) { 1055 pr_err("watchdog%d unable to add device %d:%d\n", 1056 wdd->id, MAJOR(watchdog_devt), wdd->id); 1057 if (wdd->id == 0) { 1058 misc_deregister(&watchdog_miscdev); 1059 old_wd_data = NULL; 1060 put_device(&wd_data->dev); 1061 } 1062 return err; 1063 } 1064 1065 wd_data->cdev.owner = wdd->ops->owner; 1066 1067 /* Record time of most recent heartbeat as 'just before now'. */ 1068 wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1); 1069 watchdog_set_open_deadline(wd_data); 1070 1071 /* 1072 * If the watchdog is running, prevent its driver from being unloaded, 1073 * and schedule an immediate ping. 1074 */ 1075 if (watchdog_hw_running(wdd)) { 1076 __module_get(wdd->ops->owner); 1077 get_device(&wd_data->dev); 1078 if (handle_boot_enabled) 1079 hrtimer_start(&wd_data->timer, 0, 1080 HRTIMER_MODE_REL_HARD); 1081 else 1082 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n", 1083 wdd->id); 1084 } 1085 1086 return 0; 1087 } 1088 1089 /* 1090 * watchdog_cdev_unregister: unregister watchdog character device 1091 * @watchdog: watchdog device 1092 * 1093 * Unregister watchdog character device and if needed the legacy 1094 * /dev/watchdog device. 1095 */ 1096 1097 static void watchdog_cdev_unregister(struct watchdog_device *wdd) 1098 { 1099 struct watchdog_core_data *wd_data = wdd->wd_data; 1100 1101 cdev_device_del(&wd_data->cdev, &wd_data->dev); 1102 if (wdd->id == 0) { 1103 misc_deregister(&watchdog_miscdev); 1104 old_wd_data = NULL; 1105 } 1106 1107 if (watchdog_active(wdd) && 1108 test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) { 1109 watchdog_stop(wdd); 1110 } 1111 1112 mutex_lock(&wd_data->lock); 1113 wd_data->wdd = NULL; 1114 wdd->wd_data = NULL; 1115 mutex_unlock(&wd_data->lock); 1116 1117 hrtimer_cancel(&wd_data->timer); 1118 kthread_cancel_work_sync(&wd_data->work); 1119 1120 put_device(&wd_data->dev); 1121 } 1122 1123 /* 1124 * watchdog_dev_register: register a watchdog device 1125 * @wdd: watchdog device 1126 * 1127 * Register a watchdog device including handling the legacy 1128 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and 1129 * thus we set it up like that. 1130 */ 1131 1132 int watchdog_dev_register(struct watchdog_device *wdd) 1133 { 1134 int ret; 1135 1136 ret = watchdog_cdev_register(wdd); 1137 if (ret) 1138 return ret; 1139 1140 ret = watchdog_register_pretimeout(wdd); 1141 if (ret) 1142 watchdog_cdev_unregister(wdd); 1143 1144 return ret; 1145 } 1146 1147 /* 1148 * watchdog_dev_unregister: unregister a watchdog device 1149 * @watchdog: watchdog device 1150 * 1151 * Unregister watchdog device and if needed the legacy 1152 * /dev/watchdog device. 1153 */ 1154 1155 void watchdog_dev_unregister(struct watchdog_device *wdd) 1156 { 1157 watchdog_unregister_pretimeout(wdd); 1158 watchdog_cdev_unregister(wdd); 1159 } 1160 1161 /* 1162 * watchdog_set_last_hw_keepalive: set last HW keepalive time for watchdog 1163 * @wdd: watchdog device 1164 * @last_ping_ms: time since last HW heartbeat 1165 * 1166 * Adjusts the last known HW keepalive time for a watchdog timer. 1167 * This is needed if the watchdog is already running when the probe 1168 * function is called, and it can't be pinged immediately. This 1169 * function must be called immediately after watchdog registration, 1170 * and min_hw_heartbeat_ms must be set for this to be useful. 1171 */ 1172 int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd, 1173 unsigned int last_ping_ms) 1174 { 1175 struct watchdog_core_data *wd_data; 1176 ktime_t now; 1177 1178 if (!wdd) 1179 return -EINVAL; 1180 1181 wd_data = wdd->wd_data; 1182 1183 now = ktime_get(); 1184 1185 wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms)); 1186 1187 return __watchdog_ping(wdd); 1188 } 1189 EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive); 1190 1191 /* 1192 * watchdog_dev_init: init dev part of watchdog core 1193 * 1194 * Allocate a range of chardev nodes to use for watchdog devices 1195 */ 1196 1197 int __init watchdog_dev_init(void) 1198 { 1199 int err; 1200 1201 watchdog_kworker = kthread_create_worker(0, "watchdogd"); 1202 if (IS_ERR(watchdog_kworker)) { 1203 pr_err("Failed to create watchdog kworker\n"); 1204 return PTR_ERR(watchdog_kworker); 1205 } 1206 sched_set_fifo(watchdog_kworker->task); 1207 1208 err = class_register(&watchdog_class); 1209 if (err < 0) { 1210 pr_err("couldn't register class\n"); 1211 goto err_register; 1212 } 1213 1214 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog"); 1215 if (err < 0) { 1216 pr_err("watchdog: unable to allocate char dev region\n"); 1217 goto err_alloc; 1218 } 1219 1220 return 0; 1221 1222 err_alloc: 1223 class_unregister(&watchdog_class); 1224 err_register: 1225 kthread_destroy_worker(watchdog_kworker); 1226 return err; 1227 } 1228 1229 /* 1230 * watchdog_dev_exit: exit dev part of watchdog core 1231 * 1232 * Release the range of chardev nodes used for watchdog devices 1233 */ 1234 1235 void __exit watchdog_dev_exit(void) 1236 { 1237 unregister_chrdev_region(watchdog_devt, MAX_DOGS); 1238 class_unregister(&watchdog_class); 1239 kthread_destroy_worker(watchdog_kworker); 1240 } 1241 1242 module_param(handle_boot_enabled, bool, 0444); 1243 MODULE_PARM_DESC(handle_boot_enabled, 1244 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default=" 1245 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")"); 1246 1247 module_param(open_timeout, uint, 0644); 1248 MODULE_PARM_DESC(open_timeout, 1249 "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default=" 1250 __MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")"); 1251