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 */ 57struct 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 */ 74static dev_t watchdog_devt; 75/* Reference to watchdog device behind /dev/watchdog */ 76static struct watchdog_core_data *old_wd_data; 77 78static struct kthread_worker *watchdog_kworker; 79 80static bool handle_boot_enabled = 81 IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED); 82 83static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT; 84 85static bool watchdog_past_open_deadline(struct watchdog_core_data *data) 86{ 87 return ktime_after(ktime_get(), data->open_deadline); 88} 89 90static 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 96static 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 119static 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 149static 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 164static 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 205static 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 218static 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 231static 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 243static 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 264static 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 305static 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 342static 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 375static 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 406static 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 435static 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 449static 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 457static 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} 475static DEVICE_ATTR_RW(nowayout); 476 477static 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} 490static DEVICE_ATTR_RO(status); 491 492static 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} 499static DEVICE_ATTR_RO(bootstatus); 500 501static 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} 517static DEVICE_ATTR_RO(timeleft); 518 519static 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} 526static DEVICE_ATTR_RO(timeout); 527 528static ssize_t pretimeout_show(struct device *dev, 529 struct device_attribute *attr, char *buf) 530{ 531 struct watchdog_device *wdd = dev_get_drvdata(dev); 532 533 return sprintf(buf, "%u\n", wdd->pretimeout); 534} 535static DEVICE_ATTR_RO(pretimeout); 536 537static ssize_t identity_show(struct device *dev, struct device_attribute *attr, 538 char *buf) 539{ 540 struct watchdog_device *wdd = dev_get_drvdata(dev); 541 542 return sprintf(buf, "%s\n", wdd->info->identity); 543} 544static DEVICE_ATTR_RO(identity); 545 546static ssize_t state_show(struct device *dev, struct device_attribute *attr, 547 char *buf) 548{ 549 struct watchdog_device *wdd = dev_get_drvdata(dev); 550 551 if (watchdog_active(wdd)) 552 return sprintf(buf, "active\n"); 553 554 return sprintf(buf, "inactive\n"); 555} 556static DEVICE_ATTR_RO(state); 557 558static ssize_t pretimeout_available_governors_show(struct device *dev, 559 struct device_attribute *attr, char *buf) 560{ 561 return watchdog_pretimeout_available_governors_get(buf); 562} 563static DEVICE_ATTR_RO(pretimeout_available_governors); 564 565static ssize_t pretimeout_governor_show(struct device *dev, 566 struct device_attribute *attr, 567 char *buf) 568{ 569 struct watchdog_device *wdd = dev_get_drvdata(dev); 570 571 return watchdog_pretimeout_governor_get(wdd, buf); 572} 573 574static ssize_t pretimeout_governor_store(struct device *dev, 575 struct device_attribute *attr, 576 const char *buf, size_t count) 577{ 578 struct watchdog_device *wdd = dev_get_drvdata(dev); 579 int ret = watchdog_pretimeout_governor_set(wdd, buf); 580 581 if (!ret) 582 ret = count; 583 584 return ret; 585} 586static DEVICE_ATTR_RW(pretimeout_governor); 587 588static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr, 589 int n) 590{ 591 struct device *dev = kobj_to_dev(kobj); 592 struct watchdog_device *wdd = dev_get_drvdata(dev); 593 umode_t mode = attr->mode; 594 595 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft) 596 mode = 0; 597 else if (attr == &dev_attr_pretimeout.attr && 598 !(wdd->info->options & WDIOF_PRETIMEOUT)) 599 mode = 0; 600 else if ((attr == &dev_attr_pretimeout_governor.attr || 601 attr == &dev_attr_pretimeout_available_governors.attr) && 602 (!(wdd->info->options & WDIOF_PRETIMEOUT) || 603 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV))) 604 mode = 0; 605 606 return mode; 607} 608static struct attribute *wdt_attrs[] = { 609 &dev_attr_state.attr, 610 &dev_attr_identity.attr, 611 &dev_attr_timeout.attr, 612 &dev_attr_pretimeout.attr, 613 &dev_attr_timeleft.attr, 614 &dev_attr_bootstatus.attr, 615 &dev_attr_status.attr, 616 &dev_attr_nowayout.attr, 617 &dev_attr_pretimeout_governor.attr, 618 &dev_attr_pretimeout_available_governors.attr, 619 NULL, 620}; 621 622static const struct attribute_group wdt_group = { 623 .attrs = wdt_attrs, 624 .is_visible = wdt_is_visible, 625}; 626__ATTRIBUTE_GROUPS(wdt); 627#else 628#define wdt_groups NULL 629#endif 630 631/* 632 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined 633 * @wdd: the watchdog device to do the ioctl on 634 * @cmd: watchdog command 635 * @arg: argument pointer 636 * 637 * The caller must hold wd_data->lock. 638 */ 639 640static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd, 641 unsigned long arg) 642{ 643 if (!wdd->ops->ioctl) 644 return -ENOIOCTLCMD; 645 646 return wdd->ops->ioctl(wdd, cmd, arg); 647} 648 649/* 650 * watchdog_write: writes to the watchdog. 651 * @file: file from VFS 652 * @data: user address of data 653 * @len: length of data 654 * @ppos: pointer to the file offset 655 * 656 * A write to a watchdog device is defined as a keepalive ping. 657 * Writing the magic 'V' sequence allows the next close to turn 658 * off the watchdog (if 'nowayout' is not set). 659 */ 660 661static ssize_t watchdog_write(struct file *file, const char __user *data, 662 size_t len, loff_t *ppos) 663{ 664 struct watchdog_core_data *wd_data = file->private_data; 665 struct watchdog_device *wdd; 666 int err; 667 size_t i; 668 char c; 669 670 if (len == 0) 671 return 0; 672 673 /* 674 * Note: just in case someone wrote the magic character 675 * five months ago... 676 */ 677 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status); 678 679 /* scan to see whether or not we got the magic character */ 680 for (i = 0; i != len; i++) { 681 if (get_user(c, data + i)) 682 return -EFAULT; 683 if (c == 'V') 684 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status); 685 } 686 687 /* someone wrote to us, so we send the watchdog a keepalive ping */ 688 689 err = -ENODEV; 690 mutex_lock(&wd_data->lock); 691 wdd = wd_data->wdd; 692 if (wdd) 693 err = watchdog_ping(wdd); 694 mutex_unlock(&wd_data->lock); 695 696 if (err < 0) 697 return err; 698 699 return len; 700} 701 702/* 703 * watchdog_ioctl: handle the different ioctl's for the watchdog device. 704 * @file: file handle to the device 705 * @cmd: watchdog command 706 * @arg: argument pointer 707 * 708 * The watchdog API defines a common set of functions for all watchdogs 709 * according to their available features. 710 */ 711 712static long watchdog_ioctl(struct file *file, unsigned int cmd, 713 unsigned long arg) 714{ 715 struct watchdog_core_data *wd_data = file->private_data; 716 void __user *argp = (void __user *)arg; 717 struct watchdog_device *wdd; 718 int __user *p = argp; 719 unsigned int val; 720 int err; 721 722 mutex_lock(&wd_data->lock); 723 724 wdd = wd_data->wdd; 725 if (!wdd) { 726 err = -ENODEV; 727 goto out_ioctl; 728 } 729 730 err = watchdog_ioctl_op(wdd, cmd, arg); 731 if (err != -ENOIOCTLCMD) 732 goto out_ioctl; 733 734 switch (cmd) { 735 case WDIOC_GETSUPPORT: 736 err = copy_to_user(argp, wdd->info, 737 sizeof(struct watchdog_info)) ? -EFAULT : 0; 738 break; 739 case WDIOC_GETSTATUS: 740 val = watchdog_get_status(wdd); 741 err = put_user(val, p); 742 break; 743 case WDIOC_GETBOOTSTATUS: 744 err = put_user(wdd->bootstatus, p); 745 break; 746 case WDIOC_SETOPTIONS: 747 if (get_user(val, p)) { 748 err = -EFAULT; 749 break; 750 } 751 if (val & WDIOS_DISABLECARD) { 752 err = watchdog_stop(wdd); 753 if (err < 0) 754 break; 755 } 756 if (val & WDIOS_ENABLECARD) 757 err = watchdog_start(wdd); 758 break; 759 case WDIOC_KEEPALIVE: 760 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) { 761 err = -EOPNOTSUPP; 762 break; 763 } 764 err = watchdog_ping(wdd); 765 break; 766 case WDIOC_SETTIMEOUT: 767 if (get_user(val, p)) { 768 err = -EFAULT; 769 break; 770 } 771 err = watchdog_set_timeout(wdd, val); 772 if (err < 0) 773 break; 774 /* If the watchdog is active then we send a keepalive ping 775 * to make sure that the watchdog keep's running (and if 776 * possible that it takes the new timeout) */ 777 err = watchdog_ping(wdd); 778 if (err < 0) 779 break; 780 fallthrough; 781 case WDIOC_GETTIMEOUT: 782 /* timeout == 0 means that we don't know the timeout */ 783 if (wdd->timeout == 0) { 784 err = -EOPNOTSUPP; 785 break; 786 } 787 err = put_user(wdd->timeout, p); 788 break; 789 case WDIOC_GETTIMELEFT: 790 err = watchdog_get_timeleft(wdd, &val); 791 if (err < 0) 792 break; 793 err = put_user(val, p); 794 break; 795 case WDIOC_SETPRETIMEOUT: 796 if (get_user(val, p)) { 797 err = -EFAULT; 798 break; 799 } 800 err = watchdog_set_pretimeout(wdd, val); 801 break; 802 case WDIOC_GETPRETIMEOUT: 803 err = put_user(wdd->pretimeout, p); 804 break; 805 default: 806 err = -ENOTTY; 807 break; 808 } 809 810out_ioctl: 811 mutex_unlock(&wd_data->lock); 812 return err; 813} 814 815/* 816 * watchdog_open: open the /dev/watchdog* devices. 817 * @inode: inode of device 818 * @file: file handle to device 819 * 820 * When the /dev/watchdog* device gets opened, we start the watchdog. 821 * Watch out: the /dev/watchdog device is single open, so we make sure 822 * it can only be opened once. 823 */ 824 825static int watchdog_open(struct inode *inode, struct file *file) 826{ 827 struct watchdog_core_data *wd_data; 828 struct watchdog_device *wdd; 829 bool hw_running; 830 int err; 831 832 /* Get the corresponding watchdog device */ 833 if (imajor(inode) == MISC_MAJOR) 834 wd_data = old_wd_data; 835 else 836 wd_data = container_of(inode->i_cdev, struct watchdog_core_data, 837 cdev); 838 839 /* the watchdog is single open! */ 840 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status)) 841 return -EBUSY; 842 843 wdd = wd_data->wdd; 844 845 /* 846 * If the /dev/watchdog device is open, we don't want the module 847 * to be unloaded. 848 */ 849 hw_running = watchdog_hw_running(wdd); 850 if (!hw_running && !try_module_get(wdd->ops->owner)) { 851 err = -EBUSY; 852 goto out_clear; 853 } 854 855 err = watchdog_start(wdd); 856 if (err < 0) 857 goto out_mod; 858 859 file->private_data = wd_data; 860 861 if (!hw_running) 862 get_device(&wd_data->dev); 863 864 /* 865 * open_timeout only applies for the first open from 866 * userspace. Set open_deadline to infinity so that the kernel 867 * will take care of an always-running hardware watchdog in 868 * case the device gets magic-closed or WDIOS_DISABLECARD is 869 * applied. 870 */ 871 wd_data->open_deadline = KTIME_MAX; 872 873 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */ 874 return stream_open(inode, file); 875 876out_mod: 877 module_put(wd_data->wdd->ops->owner); 878out_clear: 879 clear_bit(_WDOG_DEV_OPEN, &wd_data->status); 880 return err; 881} 882 883static void watchdog_core_data_release(struct device *dev) 884{ 885 struct watchdog_core_data *wd_data; 886 887 wd_data = container_of(dev, struct watchdog_core_data, dev); 888 889 kfree(wd_data); 890} 891 892/* 893 * watchdog_release: release the watchdog device. 894 * @inode: inode of device 895 * @file: file handle to device 896 * 897 * This is the code for when /dev/watchdog gets closed. We will only 898 * stop the watchdog when we have received the magic char (and nowayout 899 * was not set), else the watchdog will keep running. 900 */ 901 902static int watchdog_release(struct inode *inode, struct file *file) 903{ 904 struct watchdog_core_data *wd_data = file->private_data; 905 struct watchdog_device *wdd; 906 int err = -EBUSY; 907 bool running; 908 909 mutex_lock(&wd_data->lock); 910 911 wdd = wd_data->wdd; 912 if (!wdd) 913 goto done; 914 915 /* 916 * We only stop the watchdog if we received the magic character 917 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then 918 * watchdog_stop will fail. 919 */ 920 if (!watchdog_active(wdd)) 921 err = 0; 922 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) || 923 !(wdd->info->options & WDIOF_MAGICCLOSE)) 924 err = watchdog_stop(wdd); 925 926 /* If the watchdog was not stopped, send a keepalive ping */ 927 if (err < 0) { 928 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id); 929 watchdog_ping(wdd); 930 } 931 932 watchdog_update_worker(wdd); 933 934 /* make sure that /dev/watchdog can be re-opened */ 935 clear_bit(_WDOG_DEV_OPEN, &wd_data->status); 936 937done: 938 running = wdd && watchdog_hw_running(wdd); 939 mutex_unlock(&wd_data->lock); 940 /* 941 * Allow the owner module to be unloaded again unless the watchdog 942 * is still running. If the watchdog is still running, it can not 943 * be stopped, and its driver must not be unloaded. 944 */ 945 if (!running) { 946 module_put(wd_data->cdev.owner); 947 put_device(&wd_data->dev); 948 } 949 return 0; 950} 951 952static const struct file_operations watchdog_fops = { 953 .owner = THIS_MODULE, 954 .write = watchdog_write, 955 .unlocked_ioctl = watchdog_ioctl, 956 .compat_ioctl = compat_ptr_ioctl, 957 .open = watchdog_open, 958 .release = watchdog_release, 959}; 960 961static struct miscdevice watchdog_miscdev = { 962 .minor = WATCHDOG_MINOR, 963 .name = "watchdog", 964 .fops = &watchdog_fops, 965}; 966 967static struct class watchdog_class = { 968 .name = "watchdog", 969 .owner = THIS_MODULE, 970 .dev_groups = wdt_groups, 971}; 972 973/* 974 * watchdog_cdev_register: register watchdog character device 975 * @wdd: watchdog device 976 * 977 * Register a watchdog character device including handling the legacy 978 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and 979 * thus we set it up like that. 980 */ 981 982static int watchdog_cdev_register(struct watchdog_device *wdd) 983{ 984 struct watchdog_core_data *wd_data; 985 int err; 986 987 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL); 988 if (!wd_data) 989 return -ENOMEM; 990 mutex_init(&wd_data->lock); 991 992 wd_data->wdd = wdd; 993 wdd->wd_data = wd_data; 994 995 if (IS_ERR_OR_NULL(watchdog_kworker)) { 996 kfree(wd_data); 997 return -ENODEV; 998 } 999 1000 device_initialize(&wd_data->dev); 1001 wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id); 1002 wd_data->dev.class = &watchdog_class; 1003 wd_data->dev.parent = wdd->parent; 1004 wd_data->dev.groups = wdd->groups; 1005 wd_data->dev.release = watchdog_core_data_release; 1006 dev_set_drvdata(&wd_data->dev, wdd); 1007 dev_set_name(&wd_data->dev, "watchdog%d", wdd->id); 1008 1009 kthread_init_work(&wd_data->work, watchdog_ping_work); 1010 hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); 1011 wd_data->timer.function = watchdog_timer_expired; 1012 1013 if (wdd->id == 0) { 1014 old_wd_data = wd_data; 1015 watchdog_miscdev.parent = wdd->parent; 1016 err = misc_register(&watchdog_miscdev); 1017 if (err != 0) { 1018 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n", 1019 wdd->info->identity, WATCHDOG_MINOR, err); 1020 if (err == -EBUSY) 1021 pr_err("%s: a legacy watchdog module is probably present.\n", 1022 wdd->info->identity); 1023 old_wd_data = NULL; 1024 put_device(&wd_data->dev); 1025 return err; 1026 } 1027 } 1028 1029 /* Fill in the data structures */ 1030 cdev_init(&wd_data->cdev, &watchdog_fops); 1031 wd_data->cdev.owner = wdd->ops->owner; 1032 1033 /* Add the device */ 1034 err = cdev_device_add(&wd_data->cdev, &wd_data->dev); 1035 if (err) { 1036 pr_err("watchdog%d unable to add device %d:%d\n", 1037 wdd->id, MAJOR(watchdog_devt), wdd->id); 1038 if (wdd->id == 0) { 1039 misc_deregister(&watchdog_miscdev); 1040 old_wd_data = NULL; 1041 } 1042 put_device(&wd_data->dev); 1043 return err; 1044 } 1045 1046 /* Record time of most recent heartbeat as 'just before now'. */ 1047 wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1); 1048 watchdog_set_open_deadline(wd_data); 1049 1050 /* 1051 * If the watchdog is running, prevent its driver from being unloaded, 1052 * and schedule an immediate ping. 1053 */ 1054 if (watchdog_hw_running(wdd)) { 1055 __module_get(wdd->ops->owner); 1056 get_device(&wd_data->dev); 1057 if (handle_boot_enabled) 1058 hrtimer_start(&wd_data->timer, 0, 1059 HRTIMER_MODE_REL_HARD); 1060 else 1061 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n", 1062 wdd->id); 1063 } 1064 1065 return 0; 1066} 1067 1068/* 1069 * watchdog_cdev_unregister: unregister watchdog character device 1070 * @watchdog: watchdog device 1071 * 1072 * Unregister watchdog character device and if needed the legacy 1073 * /dev/watchdog device. 1074 */ 1075 1076static void watchdog_cdev_unregister(struct watchdog_device *wdd) 1077{ 1078 struct watchdog_core_data *wd_data = wdd->wd_data; 1079 1080 cdev_device_del(&wd_data->cdev, &wd_data->dev); 1081 if (wdd->id == 0) { 1082 misc_deregister(&watchdog_miscdev); 1083 old_wd_data = NULL; 1084 } 1085 1086 if (watchdog_active(wdd) && 1087 test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) { 1088 watchdog_stop(wdd); 1089 } 1090 1091 mutex_lock(&wd_data->lock); 1092 wd_data->wdd = NULL; 1093 wdd->wd_data = NULL; 1094 mutex_unlock(&wd_data->lock); 1095 1096 hrtimer_cancel(&wd_data->timer); 1097 kthread_cancel_work_sync(&wd_data->work); 1098 1099 put_device(&wd_data->dev); 1100} 1101 1102/* 1103 * watchdog_dev_register: register a watchdog device 1104 * @wdd: watchdog device 1105 * 1106 * Register a watchdog device including handling the legacy 1107 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and 1108 * thus we set it up like that. 1109 */ 1110 1111int watchdog_dev_register(struct watchdog_device *wdd) 1112{ 1113 int ret; 1114 1115 ret = watchdog_cdev_register(wdd); 1116 if (ret) 1117 return ret; 1118 1119 ret = watchdog_register_pretimeout(wdd); 1120 if (ret) 1121 watchdog_cdev_unregister(wdd); 1122 1123 return ret; 1124} 1125 1126/* 1127 * watchdog_dev_unregister: unregister a watchdog device 1128 * @watchdog: watchdog device 1129 * 1130 * Unregister watchdog device and if needed the legacy 1131 * /dev/watchdog device. 1132 */ 1133 1134void watchdog_dev_unregister(struct watchdog_device *wdd) 1135{ 1136 watchdog_unregister_pretimeout(wdd); 1137 watchdog_cdev_unregister(wdd); 1138} 1139 1140/* 1141 * watchdog_set_last_hw_keepalive: set last HW keepalive time for watchdog 1142 * @wdd: watchdog device 1143 * @last_ping_ms: time since last HW heartbeat 1144 * 1145 * Adjusts the last known HW keepalive time for a watchdog timer. 1146 * This is needed if the watchdog is already running when the probe 1147 * function is called, and it can't be pinged immediately. This 1148 * function must be called immediately after watchdog registration, 1149 * and min_hw_heartbeat_ms must be set for this to be useful. 1150 */ 1151int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd, 1152 unsigned int last_ping_ms) 1153{ 1154 struct watchdog_core_data *wd_data; 1155 ktime_t now; 1156 1157 if (!wdd) 1158 return -EINVAL; 1159 1160 wd_data = wdd->wd_data; 1161 1162 now = ktime_get(); 1163 1164 wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms)); 1165 1166 if (watchdog_hw_running(wdd) && handle_boot_enabled) 1167 return __watchdog_ping(wdd); 1168 1169 return 0; 1170} 1171EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive); 1172 1173/* 1174 * watchdog_dev_init: init dev part of watchdog core 1175 * 1176 * Allocate a range of chardev nodes to use for watchdog devices 1177 */ 1178 1179int __init watchdog_dev_init(void) 1180{ 1181 int err; 1182 1183 watchdog_kworker = kthread_create_worker(0, "watchdogd"); 1184 if (IS_ERR(watchdog_kworker)) { 1185 pr_err("Failed to create watchdog kworker\n"); 1186 return PTR_ERR(watchdog_kworker); 1187 } 1188 sched_set_fifo(watchdog_kworker->task); 1189 1190 err = class_register(&watchdog_class); 1191 if (err < 0) { 1192 pr_err("couldn't register class\n"); 1193 goto err_register; 1194 } 1195 1196 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog"); 1197 if (err < 0) { 1198 pr_err("watchdog: unable to allocate char dev region\n"); 1199 goto err_alloc; 1200 } 1201 1202 return 0; 1203 1204err_alloc: 1205 class_unregister(&watchdog_class); 1206err_register: 1207 kthread_destroy_worker(watchdog_kworker); 1208 return err; 1209} 1210 1211/* 1212 * watchdog_dev_exit: exit dev part of watchdog core 1213 * 1214 * Release the range of chardev nodes used for watchdog devices 1215 */ 1216 1217void __exit watchdog_dev_exit(void) 1218{ 1219 unregister_chrdev_region(watchdog_devt, MAX_DOGS); 1220 class_unregister(&watchdog_class); 1221 kthread_destroy_worker(watchdog_kworker); 1222} 1223 1224module_param(handle_boot_enabled, bool, 0444); 1225MODULE_PARM_DESC(handle_boot_enabled, 1226 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default=" 1227 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")"); 1228 1229module_param(open_timeout, uint, 0644); 1230MODULE_PARM_DESC(open_timeout, 1231 "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default=" 1232 __MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")"); 1233