// SPDX-License-Identifier: GPL-2.0+
/*
* 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>
*
* 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;
ktime_t open_deadline;
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 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;