diff options
Diffstat (limited to 'drivers/watchdog/watchdog_dev.c')
| -rw-r--r-- | drivers/watchdog/watchdog_dev.c | 1146 |
1 files changed, 1146 insertions, 0 deletions
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c new file mode 100644 index 000000000..8fe59b7d8 --- /dev/null +++ b/drivers/watchdog/watchdog_dev.c @@ -0,0 +1,1146 @@ +/* + * 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/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 <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 + * @dev: The watchdog's internal device + * @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 device dev; + 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; + wd_data->last_hw_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) + get_device(&wd_data->dev); + + /* 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 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. + */ + +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); + put_device(&wd_data->dev); + } + 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, +}; + +static struct class watchdog_class = { + .name = "watchdog", + .owner = THIS_MODULE, + .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. + */ + +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); + dev_set_name(&wd_data->dev, "watchdog%d", wdd->id); + + 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; + put_device(&wd_data->dev); + return err; + } + } + + /* Fill in the data structures */ + cdev_init(&wd_data->cdev, &watchdog_fops); + + /* 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; + } + + wd_data->cdev.owner = wdd->ops->owner; + + /* 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); + get_device(&wd_data->dev); + 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_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); + } + + 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. + */ + +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 + * @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); + 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)) ")"); |