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ff84136c VZ |
1 | /* |
2 | * Copyright (C) 2015-2016 Mentor Graphics | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | */ | |
10 | ||
11 | #include <linux/list.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/spinlock.h> | |
53f96cee | 14 | #include <linux/string.h> |
ff84136c VZ |
15 | #include <linux/watchdog.h> |
16 | ||
17 | #include "watchdog_pretimeout.h" | |
18 | ||
19 | /* Default watchdog pretimeout governor */ | |
20 | static struct watchdog_governor *default_gov; | |
21 | ||
22 | /* The spinlock protects default_gov, wdd->gov and pretimeout_list */ | |
23 | static DEFINE_SPINLOCK(pretimeout_lock); | |
24 | ||
25 | /* List of watchdog devices, which can generate a pretimeout event */ | |
26 | static LIST_HEAD(pretimeout_list); | |
27 | ||
28 | struct watchdog_pretimeout { | |
29 | struct watchdog_device *wdd; | |
30 | struct list_head entry; | |
31 | }; | |
32 | ||
53f96cee VZ |
33 | /* The mutex protects governor list and serializes external interfaces */ |
34 | static DEFINE_MUTEX(governor_lock); | |
35 | ||
36 | /* List of the registered watchdog pretimeout governors */ | |
37 | static LIST_HEAD(governor_list); | |
38 | ||
39 | struct governor_priv { | |
40 | struct watchdog_governor *gov; | |
41 | struct list_head entry; | |
42 | }; | |
43 | ||
44 | static struct governor_priv *find_governor_by_name(const char *gov_name) | |
45 | { | |
46 | struct governor_priv *priv; | |
47 | ||
48 | list_for_each_entry(priv, &governor_list, entry) | |
49 | if (sysfs_streq(gov_name, priv->gov->name)) | |
50 | return priv; | |
51 | ||
52 | return NULL; | |
53 | } | |
54 | ||
89873a71 VZ |
55 | int watchdog_pretimeout_available_governors_get(char *buf) |
56 | { | |
57 | struct governor_priv *priv; | |
58 | int count = 0; | |
59 | ||
60 | mutex_lock(&governor_lock); | |
61 | ||
62 | list_for_each_entry(priv, &governor_list, entry) | |
63 | count += sprintf(buf + count, "%s\n", priv->gov->name); | |
64 | ||
65 | mutex_unlock(&governor_lock); | |
66 | ||
67 | return count; | |
68 | } | |
69 | ||
ff84136c VZ |
70 | int watchdog_pretimeout_governor_get(struct watchdog_device *wdd, char *buf) |
71 | { | |
72 | int count = 0; | |
73 | ||
74 | spin_lock_irq(&pretimeout_lock); | |
75 | if (wdd->gov) | |
76 | count = sprintf(buf, "%s\n", wdd->gov->name); | |
77 | spin_unlock_irq(&pretimeout_lock); | |
78 | ||
79 | return count; | |
80 | } | |
81 | ||
53f96cee VZ |
82 | int watchdog_pretimeout_governor_set(struct watchdog_device *wdd, |
83 | const char *buf) | |
84 | { | |
85 | struct governor_priv *priv; | |
86 | ||
87 | mutex_lock(&governor_lock); | |
88 | ||
89 | priv = find_governor_by_name(buf); | |
90 | if (!priv) { | |
91 | mutex_unlock(&governor_lock); | |
92 | return -EINVAL; | |
93 | } | |
94 | ||
95 | spin_lock_irq(&pretimeout_lock); | |
96 | wdd->gov = priv->gov; | |
97 | spin_unlock_irq(&pretimeout_lock); | |
98 | ||
99 | mutex_unlock(&governor_lock); | |
100 | ||
101 | return 0; | |
102 | } | |
103 | ||
ff84136c VZ |
104 | void watchdog_notify_pretimeout(struct watchdog_device *wdd) |
105 | { | |
106 | unsigned long flags; | |
107 | ||
108 | spin_lock_irqsave(&pretimeout_lock, flags); | |
109 | if (!wdd->gov) { | |
110 | spin_unlock_irqrestore(&pretimeout_lock, flags); | |
111 | return; | |
112 | } | |
113 | ||
114 | wdd->gov->pretimeout(wdd); | |
115 | spin_unlock_irqrestore(&pretimeout_lock, flags); | |
116 | } | |
117 | EXPORT_SYMBOL_GPL(watchdog_notify_pretimeout); | |
118 | ||
119 | int watchdog_register_governor(struct watchdog_governor *gov) | |
120 | { | |
121 | struct watchdog_pretimeout *p; | |
53f96cee VZ |
122 | struct governor_priv *priv; |
123 | ||
124 | priv = kzalloc(sizeof(*priv), GFP_KERNEL); | |
125 | if (!priv) | |
126 | return -ENOMEM; | |
127 | ||
128 | mutex_lock(&governor_lock); | |
129 | ||
130 | if (find_governor_by_name(gov->name)) { | |
131 | mutex_unlock(&governor_lock); | |
132 | kfree(priv); | |
133 | return -EBUSY; | |
134 | } | |
135 | ||
136 | priv->gov = gov; | |
137 | list_add(&priv->entry, &governor_list); | |
ff84136c | 138 | |
da0d12ff VZ |
139 | if (!strncmp(gov->name, WATCHDOG_PRETIMEOUT_DEFAULT_GOV, |
140 | WATCHDOG_GOV_NAME_MAXLEN)) { | |
ff84136c VZ |
141 | spin_lock_irq(&pretimeout_lock); |
142 | default_gov = gov; | |
143 | ||
144 | list_for_each_entry(p, &pretimeout_list, entry) | |
145 | if (!p->wdd->gov) | |
146 | p->wdd->gov = default_gov; | |
147 | spin_unlock_irq(&pretimeout_lock); | |
148 | } | |
149 | ||
53f96cee VZ |
150 | mutex_unlock(&governor_lock); |
151 | ||
ff84136c VZ |
152 | return 0; |
153 | } | |
154 | EXPORT_SYMBOL(watchdog_register_governor); | |
155 | ||
156 | void watchdog_unregister_governor(struct watchdog_governor *gov) | |
157 | { | |
158 | struct watchdog_pretimeout *p; | |
53f96cee VZ |
159 | struct governor_priv *priv, *t; |
160 | ||
161 | mutex_lock(&governor_lock); | |
162 | ||
163 | list_for_each_entry_safe(priv, t, &governor_list, entry) { | |
164 | if (priv->gov == gov) { | |
165 | list_del(&priv->entry); | |
166 | kfree(priv); | |
167 | break; | |
168 | } | |
169 | } | |
ff84136c VZ |
170 | |
171 | spin_lock_irq(&pretimeout_lock); | |
ff84136c VZ |
172 | list_for_each_entry(p, &pretimeout_list, entry) |
173 | if (p->wdd->gov == gov) | |
174 | p->wdd->gov = default_gov; | |
175 | spin_unlock_irq(&pretimeout_lock); | |
53f96cee VZ |
176 | |
177 | mutex_unlock(&governor_lock); | |
ff84136c VZ |
178 | } |
179 | EXPORT_SYMBOL(watchdog_unregister_governor); | |
180 | ||
181 | int watchdog_register_pretimeout(struct watchdog_device *wdd) | |
182 | { | |
183 | struct watchdog_pretimeout *p; | |
184 | ||
185 | if (!(wdd->info->options & WDIOF_PRETIMEOUT)) | |
186 | return 0; | |
187 | ||
188 | p = kzalloc(sizeof(*p), GFP_KERNEL); | |
189 | if (!p) | |
190 | return -ENOMEM; | |
191 | ||
192 | spin_lock_irq(&pretimeout_lock); | |
193 | list_add(&p->entry, &pretimeout_list); | |
194 | p->wdd = wdd; | |
195 | wdd->gov = default_gov; | |
196 | spin_unlock_irq(&pretimeout_lock); | |
197 | ||
198 | return 0; | |
199 | } | |
200 | ||
201 | void watchdog_unregister_pretimeout(struct watchdog_device *wdd) | |
202 | { | |
203 | struct watchdog_pretimeout *p, *t; | |
204 | ||
205 | if (!(wdd->info->options & WDIOF_PRETIMEOUT)) | |
206 | return; | |
207 | ||
208 | spin_lock_irq(&pretimeout_lock); | |
209 | wdd->gov = NULL; | |
210 | ||
211 | list_for_each_entry_safe(p, t, &pretimeout_list, entry) { | |
212 | if (p->wdd == wdd) { | |
213 | list_del(&p->entry); | |
214 | break; | |
215 | } | |
216 | } | |
217 | spin_unlock_irq(&pretimeout_lock); | |
218 | ||
219 | kfree(p); | |
220 | } |