[mirror_ubuntu-kernels.git] / drivers / watchdog / watchdog_pretimeout.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2015-2016 Mentor Graphics
 */

#include <linux/list.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/watchdog.h>

#include "watchdog_pretimeout.h"

/* Default watchdog pretimeout governor */
static struct watchdog_governor *default_gov;

/* The spinlock protects default_gov, wdd->gov and pretimeout_list */
static DEFINE_SPINLOCK(pretimeout_lock);

/* List of watchdog devices, which can generate a pretimeout event */
static LIST_HEAD(pretimeout_list);

struct watchdog_pretimeout {
	struct watchdog_device		*wdd;
	struct list_head		entry;
};

/* The mutex protects governor list and serializes external interfaces */
static DEFINE_MUTEX(governor_lock);

/* List of the registered watchdog pretimeout governors */
static LIST_HEAD(governor_list);

struct governor_priv {
	struct watchdog_governor	*gov;
	struct list_head		entry;
};

static struct governor_priv *find_governor_by_name(const char *gov_name)
{
	struct governor_priv *priv;

	list_for_each_entry(priv, &governor_list, entry)
		if (sysfs_streq(gov_name, priv->gov->name))
			return priv;

	return NULL;
}

int watchdog_pretimeout_available_governors_get(char *buf)
{
	struct governor_priv *priv;
	int count = 0;

	mutex_lock(&governor_lock);

	list_for_each_entry(priv, &governor_list, entry)
		count += sprintf(buf + count, "%s\n", priv->gov->name);

	mutex_unlock(&governor_lock);

	return count;
}

int watchdog_pretimeout_governor_get(struct watchdog_device *wdd, char *buf)
{
	int count = 0;

	spin_lock_irq(&pretimeout_lock);
	if (wdd->gov)
		count = sprintf(buf, "%s\n", wdd->gov->name);
	spin_unlock_irq(&pretimeout_lock);

	return count;
}

int watchdog_pretimeout_governor_set(struct watchdog_device *wdd,
				     const char *buf)
{
	struct governor_priv *priv;

	mutex_lock(&governor_lock);

	priv = find_governor_by_name(buf);
	if (!priv) {
		mutex_unlock(&governor_lock);
		return -EINVAL;
	}

	spin_lock_irq(&pretimeout_lock);
	wdd->gov = priv->gov;
	spin_unlock_irq(&pretimeout_lock);

	mutex_unlock(&governor_lock);

	return 0;
}

void watchdog_notify_pretimeout(struct watchdog_device *wdd)
{
	unsigned long flags;

	spin_lock_irqsave(&pretimeout_lock, flags);
	if (!wdd->gov) {
		spin_unlock_irqrestore(&pretimeout_lock, flags);
		return;
	}

	wdd->gov->pretimeout(wdd);
	spin_unlock_irqrestore(&pretimeout_lock, flags);
}
EXPORT_SYMBOL_GPL(watchdog_notify_pretimeout);

int watchdog_register_governor(struct watchdog_governor *gov)
{
	struct watchdog_pretimeout *p;
	struct governor_priv *priv;

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	mutex_lock(&governor_lock);

	if (find_governor_by_name(gov->name)) {
		mutex_unlock(&governor_lock);
		kfree(priv);
		return -EBUSY;
	}

	priv->gov = gov;
	list_add(&priv->entry, &governor_list);

	if (!strncmp(gov->name, WATCHDOG_PRETIMEOUT_DEFAULT_GOV,
		     WATCHDOG_GOV_NAME_MAXLEN)) {
		spin_lock_irq(&pretimeout_lock);
		default_gov = gov;

		list_for_each_entry(p, &pretimeout_list, entry)
			if (!p->wdd->gov)
				p->wdd->gov = default_gov;
		spin_unlock_irq(&pretimeout_lock);
	}

	mutex_unlock(&governor_lock);

	return 0;
}
EXPORT_SYMBOL(watchdog_register_governor);

void watchdog_unregister_governor(struct watchdog_governor *gov)
{
	struct watchdog_pretimeout *p;
	struct governor_priv *priv, *t;

	mutex_lock(&governor_lock);

	list_for_each_entry_safe(priv, t, &governor_list, entry) {
		if (priv->gov == gov) {
			list_del(&priv->entry);
			kfree(priv);
			break;
		}
	}

	spin_lock_irq(&pretimeout_lock);
	list_for_each_entry(p, &pretimeout_list, entry)
		if (p->wdd->gov == gov)
			p->wdd->gov = default_gov;
	spin_unlock_irq(&pretimeout_lock);

	mutex_unlock(&governor_lock);
}
EXPORT_SYMBOL(watchdog_unregister_governor);

int watchdog_register_pretimeout(struct watchdog_device *wdd)
{
	struct watchdog_pretimeout *p;

	if (!(wdd->info->options & WDIOF_PRETIMEOUT))
		return 0;

	p = kzalloc(sizeof(*p), GFP_KERNEL);
	if (!p)
		return -ENOMEM;

	spin_lock_irq(&pretimeout_lock);
	list_add(&p->entry, &pretimeout_list);
	p->wdd = wdd;
	wdd->gov = default_gov;
	spin_unlock_irq(&pretimeout_lock);

	return 0;
}

void watchdog_unregister_pretimeout(struct watchdog_device *wdd)
{
	struct watchdog_pretimeout *p, *t;

	if (!(wdd->info->options & WDIOF_PRETIMEOUT))
		return;

	spin_lock_irq(&pretimeout_lock);
	wdd->gov = NULL;

	list_for_each_entry_safe(p, t, &pretimeout_list, entry) {
		if (p->wdd == wdd) {
			list_del(&p->entry);
			break;
		}
	}
	spin_unlock_irq(&pretimeout_lock);

	kfree(p);
}
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
ff84136c VZ	2	/*
ff84136c VZ	3	* Copyright (C) 2015-2016 Mentor Graphics
ff84136c VZ	4	*/
	5
	6	#include <linux/list.h>
	7	#include <linux/slab.h>
	8	#include <linux/spinlock.h>
53f96cee	9	#include <linux/string.h>
ff84136c VZ	10	#include <linux/watchdog.h>
	11
	12	#include "watchdog_pretimeout.h"
	13
	14	/* Default watchdog pretimeout governor */
	15	static struct watchdog_governor *default_gov;
	16
	17	/* The spinlock protects default_gov, wdd->gov and pretimeout_list */
	18	static DEFINE_SPINLOCK(pretimeout_lock);
	19
	20	/* List of watchdog devices, which can generate a pretimeout event */
	21	static LIST_HEAD(pretimeout_list);
	22
	23	struct watchdog_pretimeout {
	24	struct watchdog_device *wdd;
	25	struct list_head entry;
	26	};
	27
53f96cee VZ	28	/* The mutex protects governor list and serializes external interfaces */
	29	static DEFINE_MUTEX(governor_lock);
	30
	31	/* List of the registered watchdog pretimeout governors */
	32	static LIST_HEAD(governor_list);
	33
	34	struct governor_priv {
	35	struct watchdog_governor *gov;
	36	struct list_head entry;
	37	};
	38
	39	static struct governor_priv find_governor_by_name(const char gov_name)
	40	{
	41	struct governor_priv *priv;
	42
	43	list_for_each_entry(priv, &governor_list, entry)
	44	if (sysfs_streq(gov_name, priv->gov->name))
	45	return priv;
	46
	47	return NULL;
	48	}
	49
89873a71 VZ	50	int watchdog_pretimeout_available_governors_get(char *buf)
	51	{
	52	struct governor_priv *priv;
	53	int count = 0;
	54
	55	mutex_lock(&governor_lock);
	56
	57	list_for_each_entry(priv, &governor_list, entry)
	58	count += sprintf(buf + count, "%s\n", priv->gov->name);
	59
	60	mutex_unlock(&governor_lock);
	61
	62	return count;
	63	}
	64
ff84136c VZ	65	int watchdog_pretimeout_governor_get(struct watchdog_device wdd, char buf)
	66	{
	67	int count = 0;
	68
	69	spin_lock_irq(&pretimeout_lock);
	70	if (wdd->gov)
	71	count = sprintf(buf, "%s\n", wdd->gov->name);
	72	spin_unlock_irq(&pretimeout_lock);
	73
	74	return count;
	75	}
	76
53f96cee VZ	77	int watchdog_pretimeout_governor_set(struct watchdog_device *wdd,
	78	const char *buf)
	79	{
	80	struct governor_priv *priv;
	81
	82	mutex_lock(&governor_lock);
	83
	84	priv = find_governor_by_name(buf);
	85	if (!priv) {
	86	mutex_unlock(&governor_lock);
	87	return -EINVAL;
	88	}
	89
	90	spin_lock_irq(&pretimeout_lock);
	91	wdd->gov = priv->gov;
	92	spin_unlock_irq(&pretimeout_lock);
	93
	94	mutex_unlock(&governor_lock);
	95
	96	return 0;
	97	}
	98
ff84136c VZ	99	void watchdog_notify_pretimeout(struct watchdog_device *wdd)
	100	{
	101	unsigned long flags;
	102
	103	spin_lock_irqsave(&pretimeout_lock, flags);
	104	if (!wdd->gov) {
	105	spin_unlock_irqrestore(&pretimeout_lock, flags);
	106	return;
	107	}
	108
	109	wdd->gov->pretimeout(wdd);
	110	spin_unlock_irqrestore(&pretimeout_lock, flags);
	111	}
	112	EXPORT_SYMBOL_GPL(watchdog_notify_pretimeout);
	113
	114	int watchdog_register_governor(struct watchdog_governor *gov)
	115	{
	116	struct watchdog_pretimeout *p;
53f96cee VZ	117	struct governor_priv *priv;
	118
	119	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	120	if (!priv)
	121	return -ENOMEM;
	122
	123	mutex_lock(&governor_lock);
	124
	125	if (find_governor_by_name(gov->name)) {
	126	mutex_unlock(&governor_lock);
	127	kfree(priv);
	128	return -EBUSY;
	129	}
	130
	131	priv->gov = gov;
	132	list_add(&priv->entry, &governor_list);
ff84136c	133
da0d12ff VZ	134	if (!strncmp(gov->name, WATCHDOG_PRETIMEOUT_DEFAULT_GOV,
da0d12ff VZ	135	WATCHDOG_GOV_NAME_MAXLEN)) {
ff84136c VZ	136	spin_lock_irq(&pretimeout_lock);
	137	default_gov = gov;
	138
	139	list_for_each_entry(p, &pretimeout_list, entry)
	140	if (!p->wdd->gov)
	141	p->wdd->gov = default_gov;
	142	spin_unlock_irq(&pretimeout_lock);
	143	}
	144
53f96cee VZ	145	mutex_unlock(&governor_lock);
53f96cee VZ	146
ff84136c VZ	147	return 0;
	148	}
	149	EXPORT_SYMBOL(watchdog_register_governor);
	150
	151	void watchdog_unregister_governor(struct watchdog_governor *gov)
	152	{
	153	struct watchdog_pretimeout *p;
53f96cee VZ	154	struct governor_priv priv, t;
	155
	156	mutex_lock(&governor_lock);
	157
	158	list_for_each_entry_safe(priv, t, &governor_list, entry) {
	159	if (priv->gov == gov) {
	160	list_del(&priv->entry);
	161	kfree(priv);
	162	break;
	163	}
	164	}
ff84136c VZ	165
ff84136c VZ	166	spin_lock_irq(&pretimeout_lock);
ff84136c VZ	167	list_for_each_entry(p, &pretimeout_list, entry)
	168	if (p->wdd->gov == gov)
	169	p->wdd->gov = default_gov;
	170	spin_unlock_irq(&pretimeout_lock);
53f96cee VZ	171
53f96cee VZ	172	mutex_unlock(&governor_lock);
ff84136c VZ	173	}
	174	EXPORT_SYMBOL(watchdog_unregister_governor);
	175
	176	int watchdog_register_pretimeout(struct watchdog_device *wdd)
	177	{
	178	struct watchdog_pretimeout *p;
	179
	180	if (!(wdd->info->options & WDIOF_PRETIMEOUT))
	181	return 0;
	182
	183	p = kzalloc(sizeof(*p), GFP_KERNEL);
	184	if (!p)
	185	return -ENOMEM;
	186
	187	spin_lock_irq(&pretimeout_lock);
	188	list_add(&p->entry, &pretimeout_list);
	189	p->wdd = wdd;
	190	wdd->gov = default_gov;
	191	spin_unlock_irq(&pretimeout_lock);
	192
	193	return 0;
	194	}
	195
	196	void watchdog_unregister_pretimeout(struct watchdog_device *wdd)
	197	{
	198	struct watchdog_pretimeout p, t;
	199
	200	if (!(wdd->info->options & WDIOF_PRETIMEOUT))
	201	return;
	202
	203	spin_lock_irq(&pretimeout_lock);
	204	wdd->gov = NULL;
	205
	206	list_for_each_entry_safe(p, t, &pretimeout_list, entry) {
	207	if (p->wdd == wdd) {
	208	list_del(&p->entry);
	209	break;
	210	}
	211	}
	212	spin_unlock_irq(&pretimeout_lock);
	213
	214	kfree(p);
	215	}