// SPDX-License-Identifier: GPL-2.0+
/*
* watchdog_dev.c
*
* (c) Copyright 2008-2011 Alan Cox <[email protected]>,
* All Rights Reserved.
*
* (c) Copyright 2008-2011 Wim Van Sebroeck <[email protected]>.
*
* (c) Copyright 2021 Hewlett Packard Enterprise Development LP.
*
* This source code is part of the generic code that can be used
* by all the watchdog timer drivers.
*
* This part of the generic code takes care of the following
* misc device: /dev/watchdog.
*
* Based on source code of the following authors:
* Matt Domsch <[email protected]>,
* Rob Radez <[email protected]>,
* Rusty Lynch <[email protected]>
* Satyam Sharma <[email protected]>
* Randy Dunlap <[email protected]>
*
* Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
* admit liability nor provide warranty for any of this software.
* This material is provided "AS-IS" and at no charge.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/cdev.h> /* For character device */
#include <linux/errno.h> /* For the -ENODEV/... values */
#include <linux/fs.h> /* For file operations */
#include <linux/init.h> /* For __init/__exit/... */
#include <linux/hrtimer.h> /* For hrtimers */
#include <linux/kernel.h> /* For printk/panic/... */
#include <linux/kstrtox.h> /* For kstrto* */
#include <linux/kthread.h> /* For kthread_work */
#include <linux/miscdevice.h> /* For handling misc devices */
#include <linux/module.h> /* For module stuff/... */
#include <linux/mutex.h> /* For mutexes */
#include <linux/slab.h> /* For memory functions */
#include <linux/types.h> /* For standard types (like size_t) */
#include <linux/watchdog.h> /* For watchdog specific items */
#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
#include "watchdog_core.h"
#include "watchdog_pretimeout.h"
#include <trace/events/watchdog.h>
/* the dev_t structure to store the dynamically allocated watchdog devices */
static dev_t watchdog_devt;
/* Reference to watchdog device behind /dev/watchdog */
static struct watchdog_core_data *old_wd_data;
static struct kthread_worker *watchdog_kworker;
static bool handle_boot_enabled =
IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT;
static bool watchdog_past_open_deadline(struct watchdog_core_data *data)
{
return ktime_after(ktime_get(), data->open_deadline);
}
static void watchdog_set_open_deadline(struct watchdog_core_data *data)
{
data->open_deadline = open_timeout ?
ktime_get() + ktime_set(open_timeout, 0) : KTIME_MAX;
}
static inline bool watchdog_need_worker(struct watchdog_device *wdd)
{
/* All variables in milli-seconds */
unsigned int hm = wdd->max_hw_heartbeat_ms;
unsigned int t = wdd->timeout * 1000;
/*
* A worker to generate heartbeat requests is needed if all of the
* following conditions are true.
* - Userspace activated the watchdog.
* - The driver provided a value for the maximum hardware timeout, and
* thus is aware that the framework supports generating heartbeat
* requests.
* - Userspace requests a longer timeout than the hardware can handle.
*
* Alternatively, if userspace has not opened the watchdog
* device, we take care of feeding the watchdog if it is
* running.
*/
return (hm && watchdog_active(wdd) && t > hm) ||
(t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
}
static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd)
{
struct watchdog_core_data *wd_data = wdd->wd_data;
unsigned int timeout_ms = wdd->timeout * 1000;
ktime_t keepalive_interval;
ktime_t last_heartbeat, latest_heartbeat;
ktime_t virt_timeout;
unsigned int hw_heartbeat_ms;
if (watchdog_active(wdd))
virt_timeout = ktime_add(wd_data->last_keepalive,
ms_to_ktime(timeout_ms));
else
virt_timeout = wd_data->open_deadline;
hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);
/*
* To ensure that the watchdog times out wdd->timeout seconds
* after the most recent ping from userspace, the last
* worker ping has to come in hw_heartbeat_ms before this timeout.
*/
last_heartbeat = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms));
latest_heartbeat = ktime_sub(last_heartbeat, ktime_get());
if (ktime_before(latest_heartbeat, keepalive_interval))
return latest_heartbeat;
return keepalive_interval;
}
static inline void watchdog_update_worker(struct watchdog_device *wdd)
{
struct watchdog_core_data *wd_data = wdd->wd_data;
if (watchdog_need_worker(wdd)) {
ktime_t t = watchdog_next_keepalive(wdd);
if (t > 0)
hrtimer_start(&wd_data->timer, t,
HRTIMER_MODE_REL_HARD);
} else {
hrtimer_cancel(&wd_data->timer);
}
}
static int __watchdog_ping(struct watchdog_device *wdd)
{
struct watchdog_core_data *wd_data = wdd->wd_data;
ktime_t earliest_keepalive, now;
int err;
earliest_keepalive = ktime_add(wd_data->last_hw_keepalive,
ms_to_ktime(wdd->min_hw_heartbeat_ms));
now = ktime_get();
if (ktime_after(earliest_keepalive, now)) {
hrtimer_start(&wd_data->timer,
ktime_sub(earliest_keepalive, now),
HRTIMER_MODE_REL_HARD);
return 0;
}
wd_data->last_hw_keepalive = now;
if (wdd->ops->ping) {
err = wdd->ops->ping(wdd); /* ping the watchdog */
trace_watchdog_ping(wdd, err);
} else {
err = wdd->ops->start(wdd); /* restart watchdog */
trace_watchdog_start(wdd, err);
}
if (err == 0)
watchdog_hrtimer_pretimeout_start(wdd);
watchdog_update_worker(wdd);
return err;
}
/*
* watchdog_ping - ping the watchdog
* @wdd: The watchdog device to ping
*
* If the watchdog has no own ping operation then it needs to be
* restarted via the start operation. This wrapper function does
* exactly that.
* We only ping when the watchdog device is running.
* The caller must hold wd_data->lock.
*
* Return: 0 on success, error otherwise.
*/
static int watchdog_ping(struct watchdog_device *wdd)
{
struct watchdog_core_data *wd_data = wdd->wd_data;
if (!watchdog_hw_running(wdd))
return 0;
set_bit(_WDOG_KEEPALIVE, &wd_data->status);
wd_data->last_keepalive = ktime_get();
return __watchdog_ping(wdd);
}
static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data)
{
struct watchdog_device *wdd = wd_data->wdd;
if (!wdd)
return false;
if (watchdog_active(wdd))
return true;
return watchdog_hw_running(wdd) && !watchdog_past_open_deadline(wd_data);
}
static void watchdog_ping_work(struct kthread_work *work)
{
struct watchdog_core_data *wd_data;
wd_data = container_of(work, struct watchdog_core_data, work);
mutex_lock(&wd_data->lock);
if (watchdog_worker_should_ping(wd_data))
__watchdog_ping(wd_data->wdd);
mutex_unlock(&wd_data->lock);
}
static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer)
{
struct watchdog_core_data *wd_data;
wd_data = container_of(timer, struct watchdog_core_data, timer);
kthread_queue_work(watchdog_kworker, &wd_data->work);
return HRTIMER_NORESTART;
}
/*
* watchdog_start - wrapper to start the watchdog
* @wdd: The watchdog device to start
*
* Start the watchdog if it is not active and mark it active.
* The caller must hold wd_data->lock.
*
* Return: 0 on success or a negative errno code for failure.
*/
static int watchdog_start(struct watchdog_device *wdd)
{
struct watchdog_core_data *wd_data = wdd->wd_data;
ktime_t started_at;
int err;
if (watchdog_active(wdd))
return 0;
set_bit(_WDOG_KEEPALIVE, &wd_data->status);
started_at = ktime_get();
if (watchdog_hw_running(wdd) && wdd->ops->ping) {
err = __watchdog_ping(wdd);
if (err == 0) {
set_bit(WDOG_ACTIVE, &wdd->status);
watchdog_hrtimer_pretimeout_start(wdd);
}
} else {
err = wdd->ops->start(wdd);
trace_watchdog_start(wdd, err);
if (err == 0) {
set_bit(WDOG_ACTIVE, &wdd->status);
set_bit(WDOG_HW_RUNNING, &wdd->status);
wd_data->last_keepalive = started_at;
wd_data->last_hw_keepalive = started_at;
watchdog_update_worker(wdd);
watchdog_hrtimer_pretimeout_start(wdd);
}
}
return err;
}
/*
* watchdog_stop - wrapper to stop the watchdog
* @wdd: The watchdog device to stop
*
* Stop the watchdog if it is still active and unmark it active.
* If the 'nowayout' feature was set, the watchdog cannot be stopped.
* The caller must hold wd_data->lock.
*
* Return: 0 on success or a negative errno code for failure.
*/
static int watchdog_stop(struct watchdog_device *wdd)
{
int err = 0;
if (!watchdog_active(wdd))
return 0;
if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
wdd->id);
return -EBUSY;
}
if (wdd->ops->stop) {
clear_bit(WDOG_HW_RUNNING, &wdd->status);
err = wdd->ops->stop(wdd);
trace_watchdog_stop(wdd, err);
} else {
set_bit(WDOG_HW_RUNNING, &wdd->status);
}
if (err == 0) {
clear_bit(WDOG_ACTIVE, &wdd->status);
watchdog_update_worker(wdd);
watchdog_hrtimer_pretimeout_stop(wdd);
}
return err;
}
/*
* watchdog_get_status - wrapper to get the watchdog status
* @wdd: The watchdog device to get the status from
*
* Get the watchdog's status flags.
* The caller must hold wd_data->lock.
*
* Return: watchdog's status flags.
*/
static unsigned int watchdog_get_status(struct watchdog_device *wdd)
{
struct watchdog_core_data *wd_data = wdd->wd_data;
unsigned int status;
if (wdd->ops->status)
status = wdd->ops->status(wdd);
else
status = wdd->bootstatus & (WDIOF_CARDRESET |
WDIOF_OVERHEAT |
WDIOF_FANFAULT |
WDIOF_EXTERN1 |
WDIOF_EXTERN2 |
WDIOF_POWERUNDER |
WDIOF_POWEROVER);
if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
status |= WDIOF_MAGICCLOSE;
if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
status |= WDIOF_KEEPALIVEPING;
if (IS_ENABLED(CONFIG_WATCHDOG_HRTIMER_PRETIMEOUT))
status |= WDIOF_PRETIMEOUT;
return status;
}
/*
* watchdog_set_timeout - set the watchdog timer timeout
* @wdd: The watchdog device to set the timeout for
* @timeout: Timeout to set in seconds
*
* The caller must hold wd_data->lock.
*
* Return: 0 if successful, error otherwise.
*/
static int watchdog_set_timeout(struct watchdog_device *wdd,
unsigned int timeout)
{
int err = 0;
if (!(wdd->info->options & WDIOF_SETTIMEOUT))
return -EOPNOTSUPP;
if (watchdog_timeout_invalid(wdd, timeout))
return -EINVAL;
if (wdd->ops->set_timeout) {
err = wdd->ops->set_timeout(wdd, timeout);
trace_watchdog_set_timeout(wdd, timeout, err);
} else {
wdd->timeout = timeout;
/* Disable pretimeout if it doesn't fit the new timeout */
if (wdd->pretimeout >= wdd->timeout)
wdd->pretimeout = 0;
}
watchdog_update_worker(wdd);
return err;
}
/*
* watchdog_set_pretimeout - set the watchdog timer pretimeout
* @wdd: The watchdog device to set the timeout for
* @timeout: pretimeout to set in seconds
*
* Return: 0 if successful, error otherwise.
*/
static int watchdog_set_pretimeout(struct watchdog_device *wdd,
unsigned int timeout)
{
int err = 0;
if (!watchdog_have_pretimeout(wdd))
return -EOPNOTSUPP;
if (watchdog_pretimeout_invalid(wdd, timeout))
return -EINVAL;
if (wdd->ops->set_pretimeout && (wdd->info->options & WDIOF_PRETIMEOUT))
err = wdd->ops->set_pretimeout(wdd, timeout);
else
wdd->pretimeout = timeout;
return err;
}
/*
* watchdog_get_timeleft - wrapper to get the time left before a reboot
* @wdd: The watchdog device to get the remaining time from
* @timeleft: The time that's left
*
* Get the time before a watchdog will reboot (if not pinged).
* The caller must hold wd_data->lock.
*
* Return: 0 if successful, error otherwise.
*/
static int watchdog_get_timeleft(struct watchdog_device *wdd,
unsigned int *timeleft)
{
*timeleft = 0;
if (!wdd->ops->get_timeleft)
return -EOPNOTSUPP;
*timeleft = wdd->ops->get_timeleft(wdd);
return 0;
}
#ifdef CONFIG_WATCHDOG_SYSFS
static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
return sysfs_emit(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT,
&wdd->status));
}
static ssize_t nowayout_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t len)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
unsigned int value;
int ret;
ret = kstrtouint(buf, 0, &value);
if (ret)
return ret;
if (value > 1)
return -EINVAL;
/* nowayout cannot be disabled once set */
if (test_bit(WDOG_NO_WAY_OUT, &wdd->status) && !value)
return -EPERM;
watchdog_set_nowayout(wdd, value);
return len;
}
static DEVICE_ATTR_RW(nowayout);
static ssize_t status_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
struct watchdog_core_data *wd_data = wdd->wd_data;
unsigned int status;
mutex_lock(&wd_data->lock);
status = watchdog_get_status(wdd);
mutex_unlock(&wd_data->lock);
return sysfs_emit(buf, "0x%x\n", status);
}
static DEVICE_ATTR_RO(status);
static ssize_t bootstatus_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
return sysfs_emit(buf, "%u\n", wdd->bootstatus);
}
static DEVICE_ATTR_RO(bootstatus);
static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
struct watchdog_core_data *wd_data = wdd->wd_data;
ssize_t status;
unsigned int val;
mutex_lock(&wd_data->lock);
status = watchdog_get_timeleft(wdd, &val);
mutex_unlock(&wd_data->lock);
if (!status)
status = sysfs_emit(buf, "%u\n", val);
return status;
}
static DEVICE_ATTR_RO(timeleft);
static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
return sysfs_emit(buf, "%u\n", wdd->timeout);
}
static DEVICE_ATTR_RO(timeout);
static ssize_t min_timeout_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
return sysfs_emit(buf, "%u\n", wdd->min_timeout);
}
static DEVICE_ATTR_RO(min_timeout);
static ssize_t max_timeout_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
return sysfs_emit(buf, "%u\n", wdd->max_timeout);
}
static DEVICE_ATTR_RO(max_timeout);
static ssize_t pretimeout_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
return sysfs_emit(buf, "%u\n", wdd->pretimeout);
}
static DEVICE_ATTR_RO(pretimeout);
static ssize_t options_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
return sysfs_emit(buf, "0x%x\n", wdd->info->options);
}
static DEVICE_ATTR_RO(options);
static ssize_t fw_version_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
return sysfs_emit(buf, "%d\n", wdd->info->firmware_version);
}
static DEVICE_ATTR_RO(fw_version);
static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
return sysfs_emit(buf, "%s\n", wdd->info->identity);
}
static DEVICE_ATTR_RO(identity);
static ssize_t state_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
if (watchdog_active(wdd))
return sysfs_emit(buf, "active\n");
return sysfs_emit(buf, "inactive\n");
}
static DEVICE_ATTR_RO(state);
static ssize_t pretimeout_available_governors_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
return watchdog_pretimeout_available_governors_get(buf);
}
static DEVICE_ATTR_RO(pretimeout_available_governors);
static ssize_t pretimeout_governor_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
return watchdog_pretimeout_governor_get(wdd, buf);
}
static ssize_t pretimeout_governor_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct watchdog_device *wdd = dev_get_drvdata(dev);
int ret = watchdog_pretimeout_governor_set(wdd, buf);
if (!ret)
ret = count;
return ret;
}
static DEVICE_ATTR_RW(pretimeout_governor);
static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
int n)
{
struct device *dev = kobj_to_dev(kobj);
struct watchdog_device *wdd = dev_get_drvdata(dev);
umode_t mode = attr->mode;
if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
mode = 0;
else if (attr == &dev_attr_pretimeout.attr && !watchdog_have_pretimeout(wdd))
mode = 0;
else if ((attr == &dev_attr_pretimeout_governor.attr ||
attr == &dev_attr_pretimeout_available_governors.attr) &&
(!watchdog_have_pretimeout(wdd) || !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
mode = 0;
return mode;
}
static struct attribute *wdt_attrs[] = {
&dev_attr_state.attr,
&dev_attr_options.attr,
&dev_attr_fw_version.attr,
&dev_attr_identity.attr,
&dev_attr_timeout.attr,
&dev_attr_min_timeout.attr,
&dev_attr_max_timeout.attr,
&dev_attr_pretimeout.attr,
&dev_attr_timeleft.attr,
&dev_attr_bootstatus.attr,
&dev_attr_status.attr,
&dev_attr_nowayout.attr,
&dev_attr_pretimeout_governor.attr,
&dev_attr_pretimeout_available_governors.attr,
NULL,
};
static const struct attribute_group wdt_group = {
.attrs = wdt_attrs,
.is_visible = wdt_is_visible,
};
__ATTRIBUTE_GROUPS(wdt);
#else
#define wdt_groups NULL
#endif
/*
* watchdog_ioctl_op - call the watchdog drivers ioctl op if defined
* @wdd: The watchdog device to do the ioctl on
* @cmd: Watchdog command
* @arg: Argument pointer
*
* The caller must hold wd_data->lock.
*
* Return: 0 if successful, error otherwise.
*/
static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
unsigned long arg)
{
if (!wdd->ops->ioctl)
return -ENOIOCTLCMD;
return wdd->ops->ioctl(wdd, cmd, arg);
}
/*
* watchdog_write - writes to the watchdog
* @file: File from VFS
* @data: User address of data
* @len: Length of data
* @ppos: Pointer to the file offset
*
* A write to a watchdog device is defined as a keepalive ping.
* Writing the magic 'V' sequence allows the next close to turn
* off the watchdog (if 'nowayout' is not set).
*
* Return: @len if successful, error otherwise.
*/
static ssize_t watchdog_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
struct watchdog_core_data *wd_data = file->private_data;
struct watchdog_device *wdd;
int err;
size_t i;
char c;
if (len == 0)
return 0;
/*
* Note: just in case someone wrote the magic character
* five months ago...
*/
clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
/* scan to see whether or not we got the magic character */
for (i = 0; i != len; i++) {
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
}
/* someone wrote to us, so we send the watchdog a keepalive ping */
err = -ENODEV;
mutex_lock(&wd_data->lock);
wdd = wd_data->wdd;
if (wdd)
err = watchdog_ping(wdd);
mutex_unlock(&wd_data->lock);
if (err < 0)
return err;
return len;
}
/*
* watchdog_ioctl - handle the different ioctl's for the watchdog device
* @file: File handle to the device
* @cmd: Watchdog command
* @arg: Argument pointer
*
* The watchdog API defines a common set of functions for all watchdogs
* according to their available features.
*
* Return: 0 if successful, error otherwise.
*/
static long watchdog_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct watchdog_core_data *wd_data = file->private_data;
void __user *argp = (void __user *)arg;
struct watchdog_device *wdd;
int __user *p = argp;
unsigned int val;
int err;
mutex_lock(&wd_data->lock);
wdd = wd_data->wdd;
if (!wdd) {
err = -ENODEV;
goto out_ioctl;
}
err = watchdog_ioctl_op(wdd, cmd, arg);
if (err != -ENOIOCTLCMD)
goto out_ioctl;
switch (cmd) {
case WDIOC_GETSUPPORT:
err = copy_to_user(argp, wdd->info,
sizeof(struct watchdog_info)) ? -EFAULT : 0;
break;
case WDIOC_GETSTATUS:
val = watchdog_get_status(wdd);
err = put_user(val, p);
break;
case WDIOC_GETBOOTSTATUS:
err = put_user(wdd->bootstatus, p);
break;
case WDIOC_SETOPTIONS:
if (get_user(val, p)) {
err = -EFAULT;
break;
}
if (val & WDIOS_DISABLECARD) {
err = watchdog_stop(wdd);
if (err < 0)
break;
}
if (val & WDIOS_ENABLECARD)
err = watchdog_start(wdd);
break;
case WDIOC_KEEPALIVE:
if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
err = -EOPNOTSUPP;
break;
}
err = watchdog_ping(wdd);
break;
case WDIOC_SETTIMEOUT:
if (get_user(val, p)) {
err = -EFAULT;
break;
}
err = watchdog_set_timeout(wdd, val);
if (err < 0)
break;
/* If the watchdog is active then we send a keepalive ping
* to make sure that the watchdog keep's running (and if
* possible that it takes the new timeout) */
err = watchdog_ping(wdd);
if (err < 0)
break;
fallthrough;
case WDIOC_GETTIMEOUT:
/* timeout == 0 means that we don't know the timeout */
if (wdd->timeout == 0) {
err = -EOPNOTSUPP;
break;
}
err = put_user(wdd->timeout, p);
break;
case WDIOC_GETTIMELEFT:
err = watchdog_get_timeleft(wdd, &val);
if (err < 0)
break;
err = put_user(val, p);
break;
case WDIOC_SETPRETIMEOUT:
if (get_user(val, p)) {
err = -EFAULT;
break;
}
err = watchdog_set_pretimeout(wdd, val);
break;
case WDIOC_GETPRETIMEOUT:
err = put_user(wdd->pretimeout, p);
break;
default:
err = -ENOTTY;
break;
}
out_ioctl:
mutex_unlock(&wd_data->lock);
return err;
}
/*
* watchdog_open - open the /dev/watchdog* devices
* @inode: Inode of device
* @file: File handle to device
*
* When the /dev/watchdog* device gets opened, we start the watchdog.
* Watch out: the /dev/watchdog device is single open, so we make sure
* it can only be opened once.
*
* Return: 0 if successful, error otherwise.
*/
static int watchdog_open(struct inode *inode, struct file *file)
{
struct watchdog_core_data *wd_data;
struct watchdog_device *wdd;
bool hw_running;
int err;
/* Get the corresponding watchdog device */
if (imajor(inode) == MISC_MAJOR)
wd_data = old_wd_data;
else
wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
cdev);
/* the watchdog is single open! */
if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
return -EBUSY;
wdd = wd_data->wdd;
/*
* If the /dev/watchdog device is open, we don't want the module
* to be unloaded.
*/
hw_running = watchdog_hw_running(wdd);
if (!hw_running && !try_module_get(wdd->ops->owner)) {
err = -EBUSY;
goto out_clear;
}
err = watchdog_start(wdd);
if (err < 0)
goto out_mod;
file->private_data = wd_data;
if (!hw_running)
get_device(&wd_data->dev);
/*
* open_timeout only applies for the first open from
* userspace. Set open_deadline to infinity so that the kernel
* will take care of an always-running hardware watchdog in
* case the device gets magic-closed or WDIOS_DISABLECARD is
* applied.
*/
wd_data->open_deadline = KTIME_MAX;
/* dev/watchdog is a virtual (and thus non-seekable) filesystem */
return stream_open(inode, file);
out_mod:
module_put(wd_data->wdd->ops->owner);
out_clear:
clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
return err;
}
static void watchdog_core_data_release(struct device *dev)
{
struct watchdog_core_data *wd_data;
wd_data = container_of(dev, struct watchdog_core_data, dev);
kfree(wd_data);
}
/*
* watchdog_release - release the watchdog device
* @inode: Inode of device
* @file: File handle to device
*
* This is the code for when /dev/watchdog gets closed. We will only
* stop the watchdog when we have received the magic char (and nowayout
* was not set), else the watchdog will keep running.
*
* Always returns 0.
*/
static int watchdog_release(struct inode *inode, struct file *file)
{
struct watchdog_core_data *wd_data = file->private_data;
struct watchdog_device *wdd;
int err = -EBUSY;
bool running;
mutex_lock(&wd_data->lock);
wdd = wd_data->wdd;
if (!wdd)
goto done;
/*
* We only stop the watchdog if we received the magic character
* or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
* watchdog_stop will fail.
*/
if (!watchdog_active(wdd))
err = 0;
else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
!(wdd->info->options & WDIOF_MAGICCLOSE))
err = watchdog_stop(wdd);
/* If the watchdog was not stopped, send a keepalive ping */
if (err < 0) {
pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
watchdog_ping(wdd);
}
watchdog_update_worker(wdd);
/* make sure that /dev/watchdog can be re-opened */
clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
done:
running = wdd && watchdog_hw_running(wdd);
mutex_unlock(&wd_data->lock);
/*
* Allow the owner module to be unloaded again unless the watchdog
* is still running. If the watchdog is still running, it can not
* be stopped, and its driver must not be unloaded.
*/
if (!running) {
module_put(wd_data->cdev.owner);
put_device(&wd_data->dev);
}
return 0;
}
static const struct file_operations watchdog_fops = {
.owner = THIS_MODULE,
.write = watchdog_write,
.unlocked_ioctl = watchdog_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.open = watchdog_open,
.release = watchdog_release,
};
static struct miscdevice watchdog_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &watchdog_fops,
};
static const struct class watchdog_class = {
.name = "watchdog",
.dev_groups = wdt_groups,
};
/*
* watchdog_cdev_register - register watchdog character device
* @wdd: Watchdog device
*
* Register a watchdog character device including handling the legacy
* /dev/watchdog node. /dev/watchdog is actually a miscdevice and
* thus we set it up like that.
*
* Return: 0 if successful, error otherwise.
*/
static int watchdog_cdev_register(struct watchdog_device *wdd)
{
struct watchdog_core_data *wd_data;
int err;
wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
if (!wd_data)
return -ENOMEM;
mutex_init(&wd_data->lock);
wd_data->wdd = wdd;
wdd->wd_data = wd_data;
if (IS_ERR_OR_NULL(watchdog_kworker)) {
kfree(wd_data);
return -ENODEV;
}
device_initialize(&wd_data->dev);
wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id);
wd_data->dev.class = &watchdog_class;
wd_data->dev.parent = wdd->parent;
wd_data->dev.groups = wdd->groups;
wd_data->dev.release = watchdog_core_data_release;
dev_set_drvdata(&wd_data->dev, wdd);
err = dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);
if (err) {
put_device(&wd_data->dev);
return err;
}
kthread_init_work(&wd_data->work, watchdog_ping_work);
hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
wd_data->timer.function = watchdog_timer_expired;
watchdog_hrtimer_pretimeout_init(wdd);
if (wdd->id == 0) {
old_wd_data = wd_data;
watchdog_miscdev.parent = wdd->parent;
err = misc_register(&watchdog_miscdev);
if (err != 0) {
pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
wdd->info->identity, WATCHDOG_MINOR, err);
if (err == -EBUSY)
pr_err("%s: a legacy watchdog module is probably present.\n",
wdd->info->identity);
old_wd_data = NULL;
put_device(&wd_data->dev);
return err;
}
}
/* Fill in the data structures */
cdev_init(&wd_data->cdev, &watchdog_fops);
wd_data->cdev.owner = wdd->ops->owner;
/* Add the device */
err = cdev_device_add(&wd_data->cdev, &wd_data->dev);
if (err) {
pr_err("watchdog%d unable to add device %d:%d\n",
wdd->id, MAJOR(watchdog_devt), wdd->id);
if (wdd->id == 0) {
misc_deregister(&watchdog_miscdev);
old_wd_data = NULL;
}
put_device(&wd_data->dev);
return err;
}
/* Record time of most recent heartbeat as 'just before now'. */
wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1);
watchdog_set_open_deadline(wd_data);
/*
* If the watchdog is running, prevent its driver from being unloaded,
* and schedule an immediate ping.
*/
if (watchdog_hw_running(wdd)) {
__module_get(wdd->ops->owner);
get_device(&wd_data->dev);
if (handle_boot_enabled)
hrtimer_start(&wd_data->timer, 0,
HRTIMER_MODE_REL_HARD);
else
pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
wdd->id);
}
return 0;
}
/*
* watchdog_cdev_unregister - unregister watchdog character device
* @wdd: Watchdog device
*
* Unregister watchdog character device and if needed the legacy
* /dev/watchdog device.
*/
static void watchdog_cdev_unregister(struct watchdog_device *wdd)
{
struct watchdog_core_data *wd_data = wdd->wd_data;
cdev_device_del(&wd_data->cdev, &wd_data->dev);
if (wdd->id == 0) {
misc_deregister(&watchdog_miscdev);
old_wd_data = NULL;
}
if (watchdog_active(wdd) &&
test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
watchdog_stop(wdd);
}
watchdog_hrtimer_pretimeout_stop(wdd);
mutex_lock(&wd_data->lock);
wd_data->wdd = NULL;
wdd->wd_data = NULL;
mutex_unlock(&wd_data->lock);
hrtimer_cancel(&wd_data->timer);
kthread_cancel_work_sync(&wd_data->work);
put_device(&wd_data->dev);
}
/**
* watchdog_dev_register - register a watchdog device
* @wdd: Watchdog device
*
* Register a watchdog device including handling the legacy
* /dev/watchdog node. /dev/watchdog is actually a miscdevice and
* thus we set it up like that.
*
* Return: 0 if successful, error otherwise.
*/
int watchdog_dev_register(struct watchdog_device *wdd)
{
int ret;
ret = watchdog_cdev_register(wdd);
if (ret)
return ret;
ret = watchdog_register_pretimeout(wdd);
if (ret)
watchdog_cdev_unregister(wdd);
return ret;
}
/**
* watchdog_dev_unregister - unregister a watchdog device
* @wdd: watchdog device
*
* Unregister watchdog device and if needed the legacy
* /dev/watchdog device.
*/
void watchdog_dev_unregister(struct watchdog_device *wdd)
{
watchdog_unregister_pretimeout(wdd);
watchdog_cdev_unregister(wdd);
}
/**
* watchdog_set_last_hw_keepalive - set last HW keepalive time for watchdog
* @wdd: Watchdog device
* @last_ping_ms: Time since last HW heartbeat
*
* Adjusts the last known HW keepalive time for a watchdog timer.
* This is needed if the watchdog is already running when the probe
* function is called, and it can't be pinged immediately. This
* function must be called immediately after watchdog registration,
* and min_hw_heartbeat_ms must be set for this to be useful.
*
* Return: 0 if successful, error otherwise.
*/
int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,
unsigned int last_ping_ms)
{
struct watchdog_core_data *wd_data;
ktime_t now;
if (!wdd)
return -EINVAL;
wd_data = wdd->wd_data;
now = ktime_get();
wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms));
if (watchdog_hw_running(wdd) && handle_boot_enabled)
return __watchdog_ping(wdd);
return 0;
}
EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive);
/**
* watchdog_dev_init - init dev part of watchdog core
*
* Allocate a range of chardev nodes to use for watchdog devices.
*
* Return: 0 if successful, error otherwise.
*/
int __init watchdog_dev_init(void)
{
int err;
watchdog_kworker = kthread_create_worker(0, "watchdogd");
if (IS_ERR(watchdog_kworker)) {
pr_err("Failed to create watchdog kworker\n");
return PTR_ERR(watchdog_kworker);
}
sched_set_fifo(watchdog_kworker->task);
err = class_register(&watchdog_class);
if (err < 0) {
pr_err("couldn't register class\n");
goto err_register;
}
err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
if (err < 0) {
pr_err("watchdog: unable to allocate char dev region\n");
goto err_alloc;
}
return 0;
err_alloc:
class_unregister(&watchdog_class);
err_register:
kthread_destroy_worker(watchdog_kworker);
return err;
}
/**
* watchdog_dev_exit - exit dev part of watchdog core
*
* Release the range of chardev nodes used for watchdog devices.
*/
void __exit watchdog_dev_exit(void)
{
unregister_chrdev_region(watchdog_devt, MAX_DOGS);
class_unregister(&watchdog_class);
kthread_destroy_worker(watchdog_kworker);
}
int watchdog_dev_suspend(struct watchdog_device *wdd)
{
struct watchdog_core_data *wd_data = wdd->wd_data;
int ret = 0;
if (!wdd->wd_data)
return -ENODEV;
/* ping for the last time before suspend */
mutex_lock(&wd_data->lock);
if (watchdog_worker_should_ping(wd_data))
ret = __watchdog_ping(wd_data->wdd);
mutex_unlock(&wd_data->lock);
if (ret)
return ret;
/*
* make sure that watchdog worker will not kick in when the wdog is
* suspended
*/
hrtimer_cancel(&wd_data->timer);
kthread_cancel_work_sync(&wd_data->work);
return 0;
}
int watchdog_dev_resume(struct watchdog_device *wdd)
{
struct watchdog_core_data *wd_data = wdd->wd_data;
int ret = 0;
if (!wdd->wd_data)
return -ENODEV;
/*
* __watchdog_ping will also retrigger hrtimer and therefore restore the
* ping worker if needed.
*/
mutex_lock(&wd_data->lock);
if (watchdog_worker_should_ping(wd_data))
ret = __watchdog_ping(wd_data->wdd);
mutex_unlock(&wd_data->lock);
return ret;
}
module_param(handle_boot_enabled, bool, 0444);
MODULE_PARM_DESC(handle_boot_enabled,
"Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
__MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");
module_param(open_timeout, uint, 0644);
MODULE_PARM_DESC(open_timeout,
"Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default="
__MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")");
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