summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/watchdog_pretimeout.c
blob: 01ca84be240f6cfaffd61e722b9c70bf0c27c293 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
// 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);
}