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1// SPDX-License-Identifier: GPL-2.0+2/*3 * watchdog_dev.c4 *5 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,6 * All Rights Reserved.7 *8 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.9 *10 * (c) Copyright 2021 Hewlett Packard Enterprise Development LP.11 *12 * This source code is part of the generic code that can be used13 * by all the watchdog timer drivers.14 *15 * This part of the generic code takes care of the following16 * misc device: /dev/watchdog.17 *18 * Based on source code of the following authors:19 * Matt Domsch <Matt_Domsch@dell.com>,20 * Rob Radez <rob@osinvestor.com>,21 * Rusty Lynch <rusty@linux.co.intel.com>22 * Satyam Sharma <satyam@infradead.org>23 * Randy Dunlap <randy.dunlap@oracle.com>24 *25 * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.26 * admit liability nor provide warranty for any of this software.27 * This material is provided "AS-IS" and at no charge.28 */29 30#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt31 32#include <linux/cdev.h> /* For character device */33#include <linux/errno.h> /* For the -ENODEV/... values */34#include <linux/fs.h> /* For file operations */35#include <linux/init.h> /* For __init/__exit/... */36#include <linux/hrtimer.h> /* For hrtimers */37#include <linux/kernel.h> /* For printk/panic/... */38#include <linux/kstrtox.h> /* For kstrto* */39#include <linux/kthread.h> /* For kthread_work */40#include <linux/miscdevice.h> /* For handling misc devices */41#include <linux/module.h> /* For module stuff/... */42#include <linux/mutex.h> /* For mutexes */43#include <linux/slab.h> /* For memory functions */44#include <linux/types.h> /* For standard types (like size_t) */45#include <linux/watchdog.h> /* For watchdog specific items */46#include <linux/uaccess.h> /* For copy_to_user/put_user/... */47 48#include "watchdog_core.h"49#include "watchdog_pretimeout.h"50 51#include <trace/events/watchdog.h>52 53/* the dev_t structure to store the dynamically allocated watchdog devices */54static dev_t watchdog_devt;55/* Reference to watchdog device behind /dev/watchdog */56static struct watchdog_core_data *old_wd_data;57 58static struct kthread_worker *watchdog_kworker;59 60static bool handle_boot_enabled =61 IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);62 63static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT;64 65static bool watchdog_past_open_deadline(struct watchdog_core_data *data)66{67 return ktime_after(ktime_get(), data->open_deadline);68}69 70static void watchdog_set_open_deadline(struct watchdog_core_data *data)71{72 data->open_deadline = open_timeout ?73 ktime_get() + ktime_set(open_timeout, 0) : KTIME_MAX;74}75 76static inline bool watchdog_need_worker(struct watchdog_device *wdd)77{78 /* All variables in milli-seconds */79 unsigned int hm = wdd->max_hw_heartbeat_ms;80 unsigned int t = wdd->timeout * 1000;81 82 /*83 * A worker to generate heartbeat requests is needed if all of the84 * following conditions are true.85 * - Userspace activated the watchdog.86 * - The driver provided a value for the maximum hardware timeout, and87 * thus is aware that the framework supports generating heartbeat88 * requests.89 * - Userspace requests a longer timeout than the hardware can handle.90 *91 * Alternatively, if userspace has not opened the watchdog92 * device, we take care of feeding the watchdog if it is93 * running.94 */95 return (hm && watchdog_active(wdd) && t > hm) ||96 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));97}98 99static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd)100{101 struct watchdog_core_data *wd_data = wdd->wd_data;102 unsigned int timeout_ms = wdd->timeout * 1000;103 ktime_t keepalive_interval;104 ktime_t last_heartbeat, latest_heartbeat;105 ktime_t virt_timeout;106 unsigned int hw_heartbeat_ms;107 108 if (watchdog_active(wdd))109 virt_timeout = ktime_add(wd_data->last_keepalive,110 ms_to_ktime(timeout_ms));111 else112 virt_timeout = wd_data->open_deadline;113 114 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);115 keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);116 117 /*118 * To ensure that the watchdog times out wdd->timeout seconds119 * after the most recent ping from userspace, the last120 * worker ping has to come in hw_heartbeat_ms before this timeout.121 */122 last_heartbeat = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms));123 latest_heartbeat = ktime_sub(last_heartbeat, ktime_get());124 if (ktime_before(latest_heartbeat, keepalive_interval))125 return latest_heartbeat;126 return keepalive_interval;127}128 129static inline void watchdog_update_worker(struct watchdog_device *wdd)130{131 struct watchdog_core_data *wd_data = wdd->wd_data;132 133 if (watchdog_need_worker(wdd)) {134 ktime_t t = watchdog_next_keepalive(wdd);135 136 if (t > 0)137 hrtimer_start(&wd_data->timer, t,138 HRTIMER_MODE_REL_HARD);139 } else {140 hrtimer_cancel(&wd_data->timer);141 }142}143 144static int __watchdog_ping(struct watchdog_device *wdd)145{146 struct watchdog_core_data *wd_data = wdd->wd_data;147 ktime_t earliest_keepalive, now;148 int err;149 150 earliest_keepalive = ktime_add(wd_data->last_hw_keepalive,151 ms_to_ktime(wdd->min_hw_heartbeat_ms));152 now = ktime_get();153 154 if (ktime_after(earliest_keepalive, now)) {155 hrtimer_start(&wd_data->timer,156 ktime_sub(earliest_keepalive, now),157 HRTIMER_MODE_REL_HARD);158 return 0;159 }160 161 wd_data->last_hw_keepalive = now;162 163 if (wdd->ops->ping) {164 err = wdd->ops->ping(wdd); /* ping the watchdog */165 trace_watchdog_ping(wdd, err);166 } else {167 err = wdd->ops->start(wdd); /* restart watchdog */168 trace_watchdog_start(wdd, err);169 }170 171 if (err == 0)172 watchdog_hrtimer_pretimeout_start(wdd);173 174 watchdog_update_worker(wdd);175 176 return err;177}178 179/*180 * watchdog_ping - ping the watchdog181 * @wdd: The watchdog device to ping182 *183 * If the watchdog has no own ping operation then it needs to be184 * restarted via the start operation. This wrapper function does185 * exactly that.186 * We only ping when the watchdog device is running.187 * The caller must hold wd_data->lock.188 *189 * Return: 0 on success, error otherwise.190 */191static int watchdog_ping(struct watchdog_device *wdd)192{193 struct watchdog_core_data *wd_data = wdd->wd_data;194 195 if (!watchdog_hw_running(wdd))196 return 0;197 198 set_bit(_WDOG_KEEPALIVE, &wd_data->status);199 200 wd_data->last_keepalive = ktime_get();201 return __watchdog_ping(wdd);202}203 204static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data)205{206 struct watchdog_device *wdd = wd_data->wdd;207 208 if (!wdd)209 return false;210 211 if (watchdog_active(wdd))212 return true;213 214 return watchdog_hw_running(wdd) && !watchdog_past_open_deadline(wd_data);215}216 217static void watchdog_ping_work(struct kthread_work *work)218{219 struct watchdog_core_data *wd_data;220 221 wd_data = container_of(work, struct watchdog_core_data, work);222 223 mutex_lock(&wd_data->lock);224 if (watchdog_worker_should_ping(wd_data))225 __watchdog_ping(wd_data->wdd);226 mutex_unlock(&wd_data->lock);227}228 229static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer)230{231 struct watchdog_core_data *wd_data;232 233 wd_data = container_of(timer, struct watchdog_core_data, timer);234 235 kthread_queue_work(watchdog_kworker, &wd_data->work);236 return HRTIMER_NORESTART;237}238 239/*240 * watchdog_start - wrapper to start the watchdog241 * @wdd: The watchdog device to start242 *243 * Start the watchdog if it is not active and mark it active.244 * The caller must hold wd_data->lock.245 *246 * Return: 0 on success or a negative errno code for failure.247 */248static int watchdog_start(struct watchdog_device *wdd)249{250 struct watchdog_core_data *wd_data = wdd->wd_data;251 ktime_t started_at;252 int err;253 254 if (watchdog_active(wdd))255 return 0;256 257 set_bit(_WDOG_KEEPALIVE, &wd_data->status);258 259 started_at = ktime_get();260 if (watchdog_hw_running(wdd) && wdd->ops->ping) {261 err = __watchdog_ping(wdd);262 if (err == 0) {263 set_bit(WDOG_ACTIVE, &wdd->status);264 watchdog_hrtimer_pretimeout_start(wdd);265 }266 } else {267 err = wdd->ops->start(wdd);268 trace_watchdog_start(wdd, err);269 if (err == 0) {270 set_bit(WDOG_ACTIVE, &wdd->status);271 set_bit(WDOG_HW_RUNNING, &wdd->status);272 wd_data->last_keepalive = started_at;273 wd_data->last_hw_keepalive = started_at;274 watchdog_update_worker(wdd);275 watchdog_hrtimer_pretimeout_start(wdd);276 }277 }278 279 return err;280}281 282/*283 * watchdog_stop - wrapper to stop the watchdog284 * @wdd: The watchdog device to stop285 *286 * Stop the watchdog if it is still active and unmark it active.287 * If the 'nowayout' feature was set, the watchdog cannot be stopped.288 * The caller must hold wd_data->lock.289 *290 * Return: 0 on success or a negative errno code for failure.291 */292static int watchdog_stop(struct watchdog_device *wdd)293{294 int err = 0;295 296 if (!watchdog_active(wdd))297 return 0;298 299 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {300 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",301 wdd->id);302 return -EBUSY;303 }304 305 if (wdd->ops->stop) {306 clear_bit(WDOG_HW_RUNNING, &wdd->status);307 err = wdd->ops->stop(wdd);308 trace_watchdog_stop(wdd, err);309 } else {310 set_bit(WDOG_HW_RUNNING, &wdd->status);311 }312 313 if (err == 0) {314 clear_bit(WDOG_ACTIVE, &wdd->status);315 watchdog_update_worker(wdd);316 watchdog_hrtimer_pretimeout_stop(wdd);317 }318 319 return err;320}321 322/*323 * watchdog_get_status - wrapper to get the watchdog status324 * @wdd: The watchdog device to get the status from325 *326 * Get the watchdog's status flags.327 * The caller must hold wd_data->lock.328 *329 * Return: watchdog's status flags.330 */331static unsigned int watchdog_get_status(struct watchdog_device *wdd)332{333 struct watchdog_core_data *wd_data = wdd->wd_data;334 unsigned int status;335 336 if (wdd->ops->status)337 status = wdd->ops->status(wdd);338 else339 status = wdd->bootstatus & (WDIOF_CARDRESET |340 WDIOF_OVERHEAT |341 WDIOF_FANFAULT |342 WDIOF_EXTERN1 |343 WDIOF_EXTERN2 |344 WDIOF_POWERUNDER |345 WDIOF_POWEROVER);346 347 if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))348 status |= WDIOF_MAGICCLOSE;349 350 if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))351 status |= WDIOF_KEEPALIVEPING;352 353 if (IS_ENABLED(CONFIG_WATCHDOG_HRTIMER_PRETIMEOUT))354 status |= WDIOF_PRETIMEOUT;355 356 return status;357}358 359/*360 * watchdog_set_timeout - set the watchdog timer timeout361 * @wdd: The watchdog device to set the timeout for362 * @timeout: Timeout to set in seconds363 *364 * The caller must hold wd_data->lock.365 *366 * Return: 0 if successful, error otherwise.367 */368static int watchdog_set_timeout(struct watchdog_device *wdd,369 unsigned int timeout)370{371 int err = 0;372 373 if (!(wdd->info->options & WDIOF_SETTIMEOUT))374 return -EOPNOTSUPP;375 376 if (watchdog_timeout_invalid(wdd, timeout))377 return -EINVAL;378 379 if (wdd->ops->set_timeout) {380 err = wdd->ops->set_timeout(wdd, timeout);381 trace_watchdog_set_timeout(wdd, timeout, err);382 } else {383 wdd->timeout = timeout;384 /* Disable pretimeout if it doesn't fit the new timeout */385 if (wdd->pretimeout >= wdd->timeout)386 wdd->pretimeout = 0;387 }388 389 watchdog_update_worker(wdd);390 391 return err;392}393 394/*395 * watchdog_set_pretimeout - set the watchdog timer pretimeout396 * @wdd: The watchdog device to set the timeout for397 * @timeout: pretimeout to set in seconds398 *399 * Return: 0 if successful, error otherwise.400 */401static int watchdog_set_pretimeout(struct watchdog_device *wdd,402 unsigned int timeout)403{404 int err = 0;405 406 if (!watchdog_have_pretimeout(wdd))407 return -EOPNOTSUPP;408 409 if (watchdog_pretimeout_invalid(wdd, timeout))410 return -EINVAL;411 412 if (wdd->ops->set_pretimeout && (wdd->info->options & WDIOF_PRETIMEOUT))413 err = wdd->ops->set_pretimeout(wdd, timeout);414 else415 wdd->pretimeout = timeout;416 417 return err;418}419 420/*421 * watchdog_get_timeleft - wrapper to get the time left before a reboot422 * @wdd: The watchdog device to get the remaining time from423 * @timeleft: The time that's left424 *425 * Get the time before a watchdog will reboot (if not pinged).426 * The caller must hold wd_data->lock.427 *428 * Return: 0 if successful, error otherwise.429 */430static int watchdog_get_timeleft(struct watchdog_device *wdd,431 unsigned int *timeleft)432{433 *timeleft = 0;434 435 if (!wdd->ops->get_timeleft)436 return -EOPNOTSUPP;437 438 *timeleft = wdd->ops->get_timeleft(wdd);439 440 return 0;441}442 443#ifdef CONFIG_WATCHDOG_SYSFS444static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,445 char *buf)446{447 struct watchdog_device *wdd = dev_get_drvdata(dev);448 449 return sysfs_emit(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT,450 &wdd->status));451}452 453static ssize_t nowayout_store(struct device *dev, struct device_attribute *attr,454 const char *buf, size_t len)455{456 struct watchdog_device *wdd = dev_get_drvdata(dev);457 unsigned int value;458 int ret;459 460 ret = kstrtouint(buf, 0, &value);461 if (ret)462 return ret;463 if (value > 1)464 return -EINVAL;465 /* nowayout cannot be disabled once set */466 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status) && !value)467 return -EPERM;468 watchdog_set_nowayout(wdd, value);469 return len;470}471static DEVICE_ATTR_RW(nowayout);472 473static ssize_t status_show(struct device *dev, struct device_attribute *attr,474 char *buf)475{476 struct watchdog_device *wdd = dev_get_drvdata(dev);477 struct watchdog_core_data *wd_data = wdd->wd_data;478 unsigned int status;479 480 mutex_lock(&wd_data->lock);481 status = watchdog_get_status(wdd);482 mutex_unlock(&wd_data->lock);483 484 return sysfs_emit(buf, "0x%x\n", status);485}486static DEVICE_ATTR_RO(status);487 488static ssize_t bootstatus_show(struct device *dev,489 struct device_attribute *attr, char *buf)490{491 struct watchdog_device *wdd = dev_get_drvdata(dev);492 493 return sysfs_emit(buf, "%u\n", wdd->bootstatus);494}495static DEVICE_ATTR_RO(bootstatus);496 497static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,498 char *buf)499{500 struct watchdog_device *wdd = dev_get_drvdata(dev);501 struct watchdog_core_data *wd_data = wdd->wd_data;502 ssize_t status;503 unsigned int val;504 505 mutex_lock(&wd_data->lock);506 status = watchdog_get_timeleft(wdd, &val);507 mutex_unlock(&wd_data->lock);508 if (!status)509 status = sysfs_emit(buf, "%u\n", val);510 511 return status;512}513static DEVICE_ATTR_RO(timeleft);514 515static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,516 char *buf)517{518 struct watchdog_device *wdd = dev_get_drvdata(dev);519 520 return sysfs_emit(buf, "%u\n", wdd->timeout);521}522static DEVICE_ATTR_RO(timeout);523 524static ssize_t min_timeout_show(struct device *dev,525 struct device_attribute *attr, char *buf)526{527 struct watchdog_device *wdd = dev_get_drvdata(dev);528 529 return sysfs_emit(buf, "%u\n", wdd->min_timeout);530}531static DEVICE_ATTR_RO(min_timeout);532 533static ssize_t max_timeout_show(struct device *dev,534 struct device_attribute *attr, char *buf)535{536 struct watchdog_device *wdd = dev_get_drvdata(dev);537 538 return sysfs_emit(buf, "%u\n", wdd->max_timeout);539}540static DEVICE_ATTR_RO(max_timeout);541 542static ssize_t pretimeout_show(struct device *dev,543 struct device_attribute *attr, char *buf)544{545 struct watchdog_device *wdd = dev_get_drvdata(dev);546 547 return sysfs_emit(buf, "%u\n", wdd->pretimeout);548}549static DEVICE_ATTR_RO(pretimeout);550 551static ssize_t options_show(struct device *dev, struct device_attribute *attr,552 char *buf)553{554 struct watchdog_device *wdd = dev_get_drvdata(dev);555 556 return sysfs_emit(buf, "0x%x\n", wdd->info->options);557}558static DEVICE_ATTR_RO(options);559 560static ssize_t fw_version_show(struct device *dev, struct device_attribute *attr,561 char *buf)562{563 struct watchdog_device *wdd = dev_get_drvdata(dev);564 565 return sysfs_emit(buf, "%d\n", wdd->info->firmware_version);566}567static DEVICE_ATTR_RO(fw_version);568 569static ssize_t identity_show(struct device *dev, struct device_attribute *attr,570 char *buf)571{572 struct watchdog_device *wdd = dev_get_drvdata(dev);573 574 return sysfs_emit(buf, "%s\n", wdd->info->identity);575}576static DEVICE_ATTR_RO(identity);577 578static ssize_t state_show(struct device *dev, struct device_attribute *attr,579 char *buf)580{581 struct watchdog_device *wdd = dev_get_drvdata(dev);582 583 if (watchdog_active(wdd))584 return sysfs_emit(buf, "active\n");585 586 return sysfs_emit(buf, "inactive\n");587}588static DEVICE_ATTR_RO(state);589 590static ssize_t pretimeout_available_governors_show(struct device *dev,591 struct device_attribute *attr, char *buf)592{593 return watchdog_pretimeout_available_governors_get(buf);594}595static DEVICE_ATTR_RO(pretimeout_available_governors);596 597static ssize_t pretimeout_governor_show(struct device *dev,598 struct device_attribute *attr,599 char *buf)600{601 struct watchdog_device *wdd = dev_get_drvdata(dev);602 603 return watchdog_pretimeout_governor_get(wdd, buf);604}605 606static ssize_t pretimeout_governor_store(struct device *dev,607 struct device_attribute *attr,608 const char *buf, size_t count)609{610 struct watchdog_device *wdd = dev_get_drvdata(dev);611 int ret = watchdog_pretimeout_governor_set(wdd, buf);612 613 if (!ret)614 ret = count;615 616 return ret;617}618static DEVICE_ATTR_RW(pretimeout_governor);619 620static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,621 int n)622{623 struct device *dev = kobj_to_dev(kobj);624 struct watchdog_device *wdd = dev_get_drvdata(dev);625 umode_t mode = attr->mode;626 627 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)628 mode = 0;629 else if (attr == &dev_attr_pretimeout.attr && !watchdog_have_pretimeout(wdd))630 mode = 0;631 else if ((attr == &dev_attr_pretimeout_governor.attr ||632 attr == &dev_attr_pretimeout_available_governors.attr) &&633 (!watchdog_have_pretimeout(wdd) || !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))634 mode = 0;635 636 return mode;637}638static struct attribute *wdt_attrs[] = {639 &dev_attr_state.attr,640 &dev_attr_options.attr,641 &dev_attr_fw_version.attr,642 &dev_attr_identity.attr,643 &dev_attr_timeout.attr,644 &dev_attr_min_timeout.attr,645 &dev_attr_max_timeout.attr,646 &dev_attr_pretimeout.attr,647 &dev_attr_timeleft.attr,648 &dev_attr_bootstatus.attr,649 &dev_attr_status.attr,650 &dev_attr_nowayout.attr,651 &dev_attr_pretimeout_governor.attr,652 &dev_attr_pretimeout_available_governors.attr,653 NULL,654};655 656static const struct attribute_group wdt_group = {657 .attrs = wdt_attrs,658 .is_visible = wdt_is_visible,659};660__ATTRIBUTE_GROUPS(wdt);661#else662#define wdt_groups NULL663#endif664 665/*666 * watchdog_ioctl_op - call the watchdog drivers ioctl op if defined667 * @wdd: The watchdog device to do the ioctl on668 * @cmd: Watchdog command669 * @arg: Argument pointer670 *671 * The caller must hold wd_data->lock.672 *673 * Return: 0 if successful, error otherwise.674 */675static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,676 unsigned long arg)677{678 if (!wdd->ops->ioctl)679 return -ENOIOCTLCMD;680 681 return wdd->ops->ioctl(wdd, cmd, arg);682}683 684/*685 * watchdog_write - writes to the watchdog686 * @file: File from VFS687 * @data: User address of data688 * @len: Length of data689 * @ppos: Pointer to the file offset690 *691 * A write to a watchdog device is defined as a keepalive ping.692 * Writing the magic 'V' sequence allows the next close to turn693 * off the watchdog (if 'nowayout' is not set).694 *695 * Return: @len if successful, error otherwise.696 */697static ssize_t watchdog_write(struct file *file, const char __user *data,698 size_t len, loff_t *ppos)699{700 struct watchdog_core_data *wd_data = file->private_data;701 struct watchdog_device *wdd;702 int err;703 size_t i;704 char c;705 706 if (len == 0)707 return 0;708 709 /*710 * Note: just in case someone wrote the magic character711 * five months ago...712 */713 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);714 715 /* scan to see whether or not we got the magic character */716 for (i = 0; i != len; i++) {717 if (get_user(c, data + i))718 return -EFAULT;719 if (c == 'V')720 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);721 }722 723 /* someone wrote to us, so we send the watchdog a keepalive ping */724 725 err = -ENODEV;726 mutex_lock(&wd_data->lock);727 wdd = wd_data->wdd;728 if (wdd)729 err = watchdog_ping(wdd);730 mutex_unlock(&wd_data->lock);731 732 if (err < 0)733 return err;734 735 return len;736}737 738/*739 * watchdog_ioctl - handle the different ioctl's for the watchdog device740 * @file: File handle to the device741 * @cmd: Watchdog command742 * @arg: Argument pointer743 *744 * The watchdog API defines a common set of functions for all watchdogs745 * according to their available features.746 *747 * Return: 0 if successful, error otherwise.748 */749 750static long watchdog_ioctl(struct file *file, unsigned int cmd,751 unsigned long arg)752{753 struct watchdog_core_data *wd_data = file->private_data;754 void __user *argp = (void __user *)arg;755 struct watchdog_device *wdd;756 int __user *p = argp;757 unsigned int val;758 int err;759 760 mutex_lock(&wd_data->lock);761 762 wdd = wd_data->wdd;763 if (!wdd) {764 err = -ENODEV;765 goto out_ioctl;766 }767 768 err = watchdog_ioctl_op(wdd, cmd, arg);769 if (err != -ENOIOCTLCMD)770 goto out_ioctl;771 772 switch (cmd) {773 case WDIOC_GETSUPPORT:774 err = copy_to_user(argp, wdd->info,775 sizeof(struct watchdog_info)) ? -EFAULT : 0;776 break;777 case WDIOC_GETSTATUS:778 val = watchdog_get_status(wdd);779 err = put_user(val, p);780 break;781 case WDIOC_GETBOOTSTATUS:782 err = put_user(wdd->bootstatus, p);783 break;784 case WDIOC_SETOPTIONS:785 if (get_user(val, p)) {786 err = -EFAULT;787 break;788 }789 if (val & WDIOS_DISABLECARD) {790 err = watchdog_stop(wdd);791 if (err < 0)792 break;793 }794 if (val & WDIOS_ENABLECARD)795 err = watchdog_start(wdd);796 break;797 case WDIOC_KEEPALIVE:798 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {799 err = -EOPNOTSUPP;800 break;801 }802 err = watchdog_ping(wdd);803 break;804 case WDIOC_SETTIMEOUT:805 if (get_user(val, p)) {806 err = -EFAULT;807 break;808 }809 err = watchdog_set_timeout(wdd, val);810 if (err < 0)811 break;812 /* If the watchdog is active then we send a keepalive ping813 * to make sure that the watchdog keep's running (and if814 * possible that it takes the new timeout) */815 err = watchdog_ping(wdd);816 if (err < 0)817 break;818 fallthrough;819 case WDIOC_GETTIMEOUT:820 /* timeout == 0 means that we don't know the timeout */821 if (wdd->timeout == 0) {822 err = -EOPNOTSUPP;823 break;824 }825 err = put_user(wdd->timeout, p);826 break;827 case WDIOC_GETTIMELEFT:828 err = watchdog_get_timeleft(wdd, &val);829 if (err < 0)830 break;831 err = put_user(val, p);832 break;833 case WDIOC_SETPRETIMEOUT:834 if (get_user(val, p)) {835 err = -EFAULT;836 break;837 }838 err = watchdog_set_pretimeout(wdd, val);839 break;840 case WDIOC_GETPRETIMEOUT:841 err = put_user(wdd->pretimeout, p);842 break;843 default:844 err = -ENOTTY;845 break;846 }847 848out_ioctl:849 mutex_unlock(&wd_data->lock);850 return err;851}852 853/*854 * watchdog_open - open the /dev/watchdog* devices855 * @inode: Inode of device856 * @file: File handle to device857 *858 * When the /dev/watchdog* device gets opened, we start the watchdog.859 * Watch out: the /dev/watchdog device is single open, so we make sure860 * it can only be opened once.861 *862 * Return: 0 if successful, error otherwise.863 */864static int watchdog_open(struct inode *inode, struct file *file)865{866 struct watchdog_core_data *wd_data;867 struct watchdog_device *wdd;868 bool hw_running;869 int err;870 871 /* Get the corresponding watchdog device */872 if (imajor(inode) == MISC_MAJOR)873 wd_data = old_wd_data;874 else875 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,876 cdev);877 878 /* the watchdog is single open! */879 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))880 return -EBUSY;881 882 wdd = wd_data->wdd;883 884 /*885 * If the /dev/watchdog device is open, we don't want the module886 * to be unloaded.887 */888 hw_running = watchdog_hw_running(wdd);889 if (!hw_running && !try_module_get(wdd->ops->owner)) {890 err = -EBUSY;891 goto out_clear;892 }893 894 err = watchdog_start(wdd);895 if (err < 0)896 goto out_mod;897 898 file->private_data = wd_data;899 900 if (!hw_running)901 get_device(&wd_data->dev);902 903 /*904 * open_timeout only applies for the first open from905 * userspace. Set open_deadline to infinity so that the kernel906 * will take care of an always-running hardware watchdog in907 * case the device gets magic-closed or WDIOS_DISABLECARD is908 * applied.909 */910 wd_data->open_deadline = KTIME_MAX;911 912 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */913 return stream_open(inode, file);914 915out_mod:916 module_put(wd_data->wdd->ops->owner);917out_clear:918 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);919 return err;920}921 922static void watchdog_core_data_release(struct device *dev)923{924 struct watchdog_core_data *wd_data;925 926 wd_data = container_of(dev, struct watchdog_core_data, dev);927 928 kfree(wd_data);929}930 931/*932 * watchdog_release - release the watchdog device933 * @inode: Inode of device934 * @file: File handle to device935 *936 * This is the code for when /dev/watchdog gets closed. We will only937 * stop the watchdog when we have received the magic char (and nowayout938 * was not set), else the watchdog will keep running.939 *940 * Always returns 0.941 */942static int watchdog_release(struct inode *inode, struct file *file)943{944 struct watchdog_core_data *wd_data = file->private_data;945 struct watchdog_device *wdd;946 int err = -EBUSY;947 bool running;948 949 mutex_lock(&wd_data->lock);950 951 wdd = wd_data->wdd;952 if (!wdd)953 goto done;954 955 /*956 * We only stop the watchdog if we received the magic character957 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then958 * watchdog_stop will fail.959 */960 if (!watchdog_active(wdd))961 err = 0;962 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||963 !(wdd->info->options & WDIOF_MAGICCLOSE))964 err = watchdog_stop(wdd);965 966 /* If the watchdog was not stopped, send a keepalive ping */967 if (err < 0) {968 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);969 watchdog_ping(wdd);970 }971 972 watchdog_update_worker(wdd);973 974 /* make sure that /dev/watchdog can be re-opened */975 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);976 977done:978 running = wdd && watchdog_hw_running(wdd);979 mutex_unlock(&wd_data->lock);980 /*981 * Allow the owner module to be unloaded again unless the watchdog982 * is still running. If the watchdog is still running, it can not983 * be stopped, and its driver must not be unloaded.984 */985 if (!running) {986 module_put(wd_data->cdev.owner);987 put_device(&wd_data->dev);988 }989 return 0;990}991 992static const struct file_operations watchdog_fops = {993 .owner = THIS_MODULE,994 .write = watchdog_write,995 .unlocked_ioctl = watchdog_ioctl,996 .compat_ioctl = compat_ptr_ioctl,997 .open = watchdog_open,998 .release = watchdog_release,999};1000 1001static struct miscdevice watchdog_miscdev = {1002 .minor = WATCHDOG_MINOR,1003 .name = "watchdog",1004 .fops = &watchdog_fops,1005};1006 1007static const struct class watchdog_class = {1008 .name = "watchdog",1009 .dev_groups = wdt_groups,1010};1011 1012/*1013 * watchdog_cdev_register - register watchdog character device1014 * @wdd: Watchdog device1015 *1016 * Register a watchdog character device including handling the legacy1017 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and1018 * thus we set it up like that.1019 *1020 * Return: 0 if successful, error otherwise.1021 */1022static int watchdog_cdev_register(struct watchdog_device *wdd)1023{1024 struct watchdog_core_data *wd_data;1025 int err;1026 1027 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);1028 if (!wd_data)1029 return -ENOMEM;1030 mutex_init(&wd_data->lock);1031 1032 wd_data->wdd = wdd;1033 wdd->wd_data = wd_data;1034 1035 if (IS_ERR_OR_NULL(watchdog_kworker)) {1036 kfree(wd_data);1037 return -ENODEV;1038 }1039 1040 device_initialize(&wd_data->dev);1041 wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id);1042 wd_data->dev.class = &watchdog_class;1043 wd_data->dev.parent = wdd->parent;1044 wd_data->dev.groups = wdd->groups;1045 wd_data->dev.release = watchdog_core_data_release;1046 dev_set_drvdata(&wd_data->dev, wdd);1047 err = dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);1048 if (err) {1049 put_device(&wd_data->dev);1050 return err;1051 }1052 1053 kthread_init_work(&wd_data->work, watchdog_ping_work);1054 hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);1055 wd_data->timer.function = watchdog_timer_expired;1056 watchdog_hrtimer_pretimeout_init(wdd);1057 1058 if (wdd->id == 0) {1059 old_wd_data = wd_data;1060 watchdog_miscdev.parent = wdd->parent;1061 err = misc_register(&watchdog_miscdev);1062 if (err != 0) {1063 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",1064 wdd->info->identity, WATCHDOG_MINOR, err);1065 if (err == -EBUSY)1066 pr_err("%s: a legacy watchdog module is probably present.\n",1067 wdd->info->identity);1068 old_wd_data = NULL;1069 put_device(&wd_data->dev);1070 return err;1071 }1072 }1073 1074 /* Fill in the data structures */1075 cdev_init(&wd_data->cdev, &watchdog_fops);1076 wd_data->cdev.owner = wdd->ops->owner;1077 1078 /* Add the device */1079 err = cdev_device_add(&wd_data->cdev, &wd_data->dev);1080 if (err) {1081 pr_err("watchdog%d unable to add device %d:%d\n",1082 wdd->id, MAJOR(watchdog_devt), wdd->id);1083 if (wdd->id == 0) {1084 misc_deregister(&watchdog_miscdev);1085 old_wd_data = NULL;1086 }1087 put_device(&wd_data->dev);1088 return err;1089 }1090 1091 /* Record time of most recent heartbeat as 'just before now'. */1092 wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1);1093 watchdog_set_open_deadline(wd_data);1094 1095 /*1096 * If the watchdog is running, prevent its driver from being unloaded,1097 * and schedule an immediate ping.1098 */1099 if (watchdog_hw_running(wdd)) {1100 __module_get(wdd->ops->owner);1101 get_device(&wd_data->dev);1102 if (handle_boot_enabled)1103 hrtimer_start(&wd_data->timer, 0,1104 HRTIMER_MODE_REL_HARD);1105 else1106 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",1107 wdd->id);1108 }1109 1110 return 0;1111}1112 1113/*1114 * watchdog_cdev_unregister - unregister watchdog character device1115 * @wdd: Watchdog device1116 *1117 * Unregister watchdog character device and if needed the legacy1118 * /dev/watchdog device.1119 */1120static void watchdog_cdev_unregister(struct watchdog_device *wdd)1121{1122 struct watchdog_core_data *wd_data = wdd->wd_data;1123 1124 cdev_device_del(&wd_data->cdev, &wd_data->dev);1125 if (wdd->id == 0) {1126 misc_deregister(&watchdog_miscdev);1127 old_wd_data = NULL;1128 }1129 1130 if (watchdog_active(wdd) &&1131 test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {1132 watchdog_stop(wdd);1133 }1134 1135 watchdog_hrtimer_pretimeout_stop(wdd);1136 1137 mutex_lock(&wd_data->lock);1138 wd_data->wdd = NULL;1139 wdd->wd_data = NULL;1140 mutex_unlock(&wd_data->lock);1141 1142 hrtimer_cancel(&wd_data->timer);1143 kthread_cancel_work_sync(&wd_data->work);1144 1145 put_device(&wd_data->dev);1146}1147 1148/**1149 * watchdog_dev_register - register a watchdog device1150 * @wdd: Watchdog device1151 *1152 * Register a watchdog device including handling the legacy1153 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and1154 * thus we set it up like that.1155 *1156 * Return: 0 if successful, error otherwise.1157 */1158int watchdog_dev_register(struct watchdog_device *wdd)1159{1160 int ret;1161 1162 ret = watchdog_cdev_register(wdd);1163 if (ret)1164 return ret;1165 1166 ret = watchdog_register_pretimeout(wdd);1167 if (ret)1168 watchdog_cdev_unregister(wdd);1169 1170 return ret;1171}1172 1173/**1174 * watchdog_dev_unregister - unregister a watchdog device1175 * @wdd: watchdog device1176 *1177 * Unregister watchdog device and if needed the legacy1178 * /dev/watchdog device.1179 */1180void watchdog_dev_unregister(struct watchdog_device *wdd)1181{1182 watchdog_unregister_pretimeout(wdd);1183 watchdog_cdev_unregister(wdd);1184}1185 1186/**1187 * watchdog_set_last_hw_keepalive - set last HW keepalive time for watchdog1188 * @wdd: Watchdog device1189 * @last_ping_ms: Time since last HW heartbeat1190 *1191 * Adjusts the last known HW keepalive time for a watchdog timer.1192 * This is needed if the watchdog is already running when the probe1193 * function is called, and it can't be pinged immediately. This1194 * function must be called immediately after watchdog registration,1195 * and min_hw_heartbeat_ms must be set for this to be useful.1196 *1197 * Return: 0 if successful, error otherwise.1198 */1199int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,1200 unsigned int last_ping_ms)1201{1202 struct watchdog_core_data *wd_data;1203 ktime_t now;1204 1205 if (!wdd)1206 return -EINVAL;1207 1208 wd_data = wdd->wd_data;1209 1210 now = ktime_get();1211 1212 wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms));1213 1214 if (watchdog_hw_running(wdd) && handle_boot_enabled)1215 return __watchdog_ping(wdd);1216 1217 return 0;1218}1219EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive);1220 1221/**1222 * watchdog_dev_init - init dev part of watchdog core1223 *1224 * Allocate a range of chardev nodes to use for watchdog devices.1225 *1226 * Return: 0 if successful, error otherwise.1227 */1228int __init watchdog_dev_init(void)1229{1230 int err;1231 1232 watchdog_kworker = kthread_create_worker(0, "watchdogd");1233 if (IS_ERR(watchdog_kworker)) {1234 pr_err("Failed to create watchdog kworker\n");1235 return PTR_ERR(watchdog_kworker);1236 }1237 sched_set_fifo(watchdog_kworker->task);1238 1239 err = class_register(&watchdog_class);1240 if (err < 0) {1241 pr_err("couldn't register class\n");1242 goto err_register;1243 }1244 1245 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");1246 if (err < 0) {1247 pr_err("watchdog: unable to allocate char dev region\n");1248 goto err_alloc;1249 }1250 1251 return 0;1252 1253err_alloc:1254 class_unregister(&watchdog_class);1255err_register:1256 kthread_destroy_worker(watchdog_kworker);1257 return err;1258}1259 1260/**1261 * watchdog_dev_exit - exit dev part of watchdog core1262 *1263 * Release the range of chardev nodes used for watchdog devices.1264 */1265void __exit watchdog_dev_exit(void)1266{1267 unregister_chrdev_region(watchdog_devt, MAX_DOGS);1268 class_unregister(&watchdog_class);1269 kthread_destroy_worker(watchdog_kworker);1270}1271 1272int watchdog_dev_suspend(struct watchdog_device *wdd)1273{1274 struct watchdog_core_data *wd_data = wdd->wd_data;1275 int ret = 0;1276 1277 if (!wdd->wd_data)1278 return -ENODEV;1279 1280 /* ping for the last time before suspend */1281 mutex_lock(&wd_data->lock);1282 if (watchdog_worker_should_ping(wd_data))1283 ret = __watchdog_ping(wd_data->wdd);1284 mutex_unlock(&wd_data->lock);1285 1286 if (ret)1287 return ret;1288 1289 /*1290 * make sure that watchdog worker will not kick in when the wdog is1291 * suspended1292 */1293 hrtimer_cancel(&wd_data->timer);1294 kthread_cancel_work_sync(&wd_data->work);1295 1296 return 0;1297}1298 1299int watchdog_dev_resume(struct watchdog_device *wdd)1300{1301 struct watchdog_core_data *wd_data = wdd->wd_data;1302 int ret = 0;1303 1304 if (!wdd->wd_data)1305 return -ENODEV;1306 1307 /*1308 * __watchdog_ping will also retrigger hrtimer and therefore restore the1309 * ping worker if needed.1310 */1311 mutex_lock(&wd_data->lock);1312 if (watchdog_worker_should_ping(wd_data))1313 ret = __watchdog_ping(wd_data->wdd);1314 mutex_unlock(&wd_data->lock);1315 1316 return ret;1317}1318 1319module_param(handle_boot_enabled, bool, 0444);1320MODULE_PARM_DESC(handle_boot_enabled,1321 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="1322 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");1323 1324module_param(open_timeout, uint, 0644);1325MODULE_PARM_DESC(open_timeout,1326 "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default="1327 __MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")");1328