v4.19.13 snapshot.
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
new file mode 100644
index 0000000..ffbdc46
--- /dev/null
+++ b/drivers/watchdog/watchdog_dev.c
@@ -0,0 +1,1183 @@
+/*
+ * watchdog_dev.c
+ *
+ * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
+ * All Rights Reserved.
+ *
+ * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
+ *
+ *
+ * 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 <Matt_Domsch@dell.com>,
+ * Rob Radez <rob@osinvestor.com>,
+ * Rusty Lynch <rusty@linux.co.intel.com>
+ * Satyam Sharma <satyam@infradead.org>
+ * Randy Dunlap <randy.dunlap@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * 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/kref.h> /* For data references */
+#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/reboot.h> /* For reboot notifier */
+#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 <uapi/linux/sched/types.h> /* For struct sched_param */
+
+#include "watchdog_core.h"
+#include "watchdog_pretimeout.h"
+
+/*
+ * struct watchdog_core_data - watchdog core internal data
+ * @kref: Reference count.
+ * @cdev: The watchdog's Character device.
+ * @wdd: Pointer to watchdog device.
+ * @lock: Lock for watchdog core.
+ * @status: Watchdog core internal status bits.
+ */
+struct watchdog_core_data {
+ struct kref kref;
+ struct cdev cdev;
+ struct watchdog_device *wdd;
+ struct mutex lock;
+ ktime_t last_keepalive;
+ ktime_t last_hw_keepalive;
+ struct hrtimer timer;
+ struct kthread_work work;
+ unsigned long status; /* Internal status bits */
+#define _WDOG_DEV_OPEN 0 /* Opened ? */
+#define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */
+#define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */
+};
+
+/* 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 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;
+
+ virt_timeout = ktime_add(wd_data->last_keepalive,
+ ms_to_ktime(timeout_ms));
+ hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
+ keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);
+
+ if (!watchdog_active(wdd))
+ return keepalive_interval;
+
+ /*
+ * 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);
+ } 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);
+ return 0;
+ }
+
+ wd_data->last_hw_keepalive = now;
+
+ if (wdd->ops->ping)
+ err = wdd->ops->ping(wdd); /* ping the watchdog */
+ else
+ err = wdd->ops->start(wdd); /* restart watchdog */
+
+ watchdog_update_worker(wdd);
+
+ return err;
+}
+
+/*
+ * watchdog_ping: ping the watchdog.
+ * @wdd: the watchdog device to ping
+ *
+ * The caller must hold wd_data->lock.
+ *
+ * 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.
+ */
+
+static int watchdog_ping(struct watchdog_device *wdd)
+{
+ struct watchdog_core_data *wd_data = wdd->wd_data;
+
+ if (!watchdog_active(wdd) && !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;
+
+ return wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd));
+}
+
+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
+ *
+ * The caller must hold wd_data->lock.
+ *
+ * Start the watchdog if it is not active and mark it active.
+ * This function returns zero 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 = wdd->ops->ping(wdd);
+ else
+ err = wdd->ops->start(wdd);
+ if (err == 0) {
+ set_bit(WDOG_ACTIVE, &wdd->status);
+ wd_data->last_keepalive = started_at;
+ watchdog_update_worker(wdd);
+ }
+
+ return err;
+}
+
+/*
+ * watchdog_stop: wrapper to stop the watchdog.
+ * @wdd: the watchdog device to stop
+ *
+ * The caller must hold wd_data->lock.
+ *
+ * Stop the watchdog if it is still active and unmark it active.
+ * This function returns zero on success or a negative errno code for
+ * failure.
+ * If the 'nowayout' feature was set, the watchdog cannot be stopped.
+ */
+
+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);
+ } else {
+ set_bit(WDOG_HW_RUNNING, &wdd->status);
+ }
+
+ if (err == 0) {
+ clear_bit(WDOG_ACTIVE, &wdd->status);
+ watchdog_update_worker(wdd);
+ }
+
+ return err;
+}
+
+/*
+ * watchdog_get_status: wrapper to get the watchdog status
+ * @wdd: the watchdog device to get the status from
+ *
+ * The caller must hold wd_data->lock.
+ *
+ * Get the 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;
+
+ 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.
+ */
+
+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);
+ } 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
+ */
+
+static int watchdog_set_pretimeout(struct watchdog_device *wdd,
+ unsigned int timeout)
+{
+ int err = 0;
+
+ if (!(wdd->info->options & WDIOF_PRETIMEOUT))
+ return -EOPNOTSUPP;
+
+ if (watchdog_pretimeout_invalid(wdd, timeout))
+ return -EINVAL;
+
+ if (wdd->ops->set_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
+ *
+ * The caller must hold wd_data->lock.
+ *
+ * Get the time before a watchdog will reboot (if not pinged).
+ */
+
+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 sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
+}
+static DEVICE_ATTR_RO(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 sprintf(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 sprintf(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 = sprintf(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 sprintf(buf, "%u\n", wdd->timeout);
+}
+static DEVICE_ATTR_RO(timeout);
+
+static ssize_t pretimeout_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+ return sprintf(buf, "%u\n", wdd->pretimeout);
+}
+static DEVICE_ATTR_RO(pretimeout);
+
+static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+ return sprintf(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 sprintf(buf, "active\n");
+
+ return sprintf(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 = container_of(kobj, struct device, 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 &&
+ !(wdd->info->options & WDIOF_PRETIMEOUT))
+ mode = 0;
+ else if ((attr == &dev_attr_pretimeout_governor.attr ||
+ attr == &dev_attr_pretimeout_available_governors.attr) &&
+ (!(wdd->info->options & WDIOF_PRETIMEOUT) ||
+ !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
+ mode = 0;
+
+ return mode;
+}
+static struct attribute *wdt_attrs[] = {
+ &dev_attr_state.attr,
+ &dev_attr_identity.attr,
+ &dev_attr_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.
+ */
+
+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).
+ */
+
+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.
+ */
+
+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;
+ /* fall through */
+ 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.
+ */
+
+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)
+ kref_get(&wd_data->kref);
+
+ /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
+ return nonseekable_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 kref *kref)
+{
+ struct watchdog_core_data *wd_data;
+
+ wd_data = container_of(kref, struct watchdog_core_data, kref);
+
+ 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.
+ */
+
+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 (!test_bit(WDOG_ACTIVE, &wdd->status))
+ 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);
+ kref_put(&wd_data->kref, watchdog_core_data_release);
+ }
+ return 0;
+}
+
+static const struct file_operations watchdog_fops = {
+ .owner = THIS_MODULE,
+ .write = watchdog_write,
+ .unlocked_ioctl = watchdog_ioctl,
+ .open = watchdog_open,
+ .release = watchdog_release,
+};
+
+static struct miscdevice watchdog_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &watchdog_fops,
+};
+
+/*
+ * watchdog_cdev_register: register watchdog character device
+ * @wdd: watchdog device
+ * @devno: character device number
+ *
+ * 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.
+ */
+
+static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
+{
+ struct watchdog_core_data *wd_data;
+ int err;
+
+ wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
+ if (!wd_data)
+ return -ENOMEM;
+ kref_init(&wd_data->kref);
+ mutex_init(&wd_data->lock);
+
+ wd_data->wdd = wdd;
+ wdd->wd_data = wd_data;
+
+ if (IS_ERR_OR_NULL(watchdog_kworker))
+ return -ENODEV;
+
+ kthread_init_work(&wd_data->work, watchdog_ping_work);
+ hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ wd_data->timer.function = watchdog_timer_expired;
+
+ 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;
+ kfree(wd_data);
+ 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_add(&wd_data->cdev, devno, 1);
+ 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;
+ kref_put(&wd_data->kref, watchdog_core_data_release);
+ }
+ return err;
+ }
+
+ /* Record time of most recent heartbeat as 'just before now'. */
+ wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1);
+
+ /*
+ * 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);
+ kref_get(&wd_data->kref);
+ if (handle_boot_enabled)
+ hrtimer_start(&wd_data->timer, 0, HRTIMER_MODE_REL);
+ 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
+ * @watchdog: 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_del(&wd_data->cdev);
+ if (wdd->id == 0) {
+ misc_deregister(&watchdog_miscdev);
+ old_wd_data = NULL;
+ }
+
+ mutex_lock(&wd_data->lock);
+ wd_data->wdd = NULL;
+ wdd->wd_data = NULL;
+ mutex_unlock(&wd_data->lock);
+
+ if (watchdog_active(wdd) &&
+ test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
+ watchdog_stop(wdd);
+ }
+
+ hrtimer_cancel(&wd_data->timer);
+ kthread_cancel_work_sync(&wd_data->work);
+
+ kref_put(&wd_data->kref, watchdog_core_data_release);
+}
+
+static struct class watchdog_class = {
+ .name = "watchdog",
+ .owner = THIS_MODULE,
+ .dev_groups = wdt_groups,
+};
+
+static int watchdog_reboot_notifier(struct notifier_block *nb,
+ unsigned long code, void *data)
+{
+ struct watchdog_device *wdd;
+
+ wdd = container_of(nb, struct watchdog_device, reboot_nb);
+ if (code == SYS_DOWN || code == SYS_HALT) {
+ if (watchdog_active(wdd)) {
+ int ret;
+
+ ret = wdd->ops->stop(wdd);
+ if (ret)
+ return NOTIFY_BAD;
+ }
+ }
+
+ return NOTIFY_DONE;
+}
+
+/*
+ * 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.
+ */
+
+int watchdog_dev_register(struct watchdog_device *wdd)
+{
+ struct device *dev;
+ dev_t devno;
+ int ret;
+
+ devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
+
+ ret = watchdog_cdev_register(wdd, devno);
+ if (ret)
+ return ret;
+
+ dev = device_create_with_groups(&watchdog_class, wdd->parent,
+ devno, wdd, wdd->groups,
+ "watchdog%d", wdd->id);
+ if (IS_ERR(dev)) {
+ watchdog_cdev_unregister(wdd);
+ return PTR_ERR(dev);
+ }
+
+ ret = watchdog_register_pretimeout(wdd);
+ if (ret) {
+ device_destroy(&watchdog_class, devno);
+ watchdog_cdev_unregister(wdd);
+ return ret;
+ }
+
+ if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
+ wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
+
+ ret = devm_register_reboot_notifier(dev, &wdd->reboot_nb);
+ if (ret) {
+ pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
+ wdd->id, ret);
+ watchdog_dev_unregister(wdd);
+ }
+ }
+
+ return ret;
+}
+
+/*
+ * watchdog_dev_unregister: unregister a watchdog device
+ * @watchdog: 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);
+ device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
+ watchdog_cdev_unregister(wdd);
+}
+
+/*
+ * watchdog_dev_init: init dev part of watchdog core
+ *
+ * Allocate a range of chardev nodes to use for watchdog devices
+ */
+
+int __init watchdog_dev_init(void)
+{
+ int err;
+ struct sched_param param = {.sched_priority = MAX_RT_PRIO - 1,};
+
+ 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_setscheduler(watchdog_kworker->task, SCHED_FIFO, ¶m);
+
+ 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);
+}
+
+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)) ")");