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43316044 WVS |
1 | /* |
2 | * watchdog_core.c | |
3 | * | |
4 | * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>, | |
5 | * All Rights Reserved. | |
6 | * | |
7 | * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>. | |
8 | * | |
9 | * This source code is part of the generic code that can be used | |
10 | * by all the watchdog timer drivers. | |
11 | * | |
12 | * Based on source code of the following authors: | |
13 | * Matt Domsch <Matt_Domsch@dell.com>, | |
14 | * Rob Radez <rob@osinvestor.com>, | |
15 | * Rusty Lynch <rusty@linux.co.intel.com> | |
16 | * Satyam Sharma <satyam@infradead.org> | |
17 | * Randy Dunlap <randy.dunlap@oracle.com> | |
18 | * | |
19 | * This program is free software; you can redistribute it and/or | |
20 | * modify it under the terms of the GNU General Public License | |
21 | * as published by the Free Software Foundation; either version | |
22 | * 2 of the License, or (at your option) any later version. | |
23 | * | |
24 | * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw. | |
25 | * admit liability nor provide warranty for any of this software. | |
26 | * This material is provided "AS-IS" and at no charge. | |
27 | */ | |
28 | ||
29 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
30 | ||
31 | #include <linux/module.h> /* For EXPORT_SYMBOL/module stuff/... */ | |
32 | #include <linux/types.h> /* For standard types */ | |
33 | #include <linux/errno.h> /* For the -ENODEV/... values */ | |
34 | #include <linux/kernel.h> /* For printk/panic/... */ | |
35 | #include <linux/watchdog.h> /* For watchdog specific items */ | |
36 | #include <linux/init.h> /* For __init/__exit/... */ | |
45f5fed3 | 37 | #include <linux/idr.h> /* For ida_* macros */ |
d6b469d9 | 38 | #include <linux/err.h> /* For IS_ERR macros */ |
3048253e | 39 | #include <linux/of.h> /* For of_get_timeout_sec */ |
43316044 | 40 | |
6cfb5aa8 | 41 | #include "watchdog_core.h" /* For watchdog_dev_register/... */ |
43316044 | 42 | |
45f5fed3 | 43 | static DEFINE_IDA(watchdog_ida); |
d6b469d9 | 44 | static struct class *watchdog_class; |
45f5fed3 | 45 | |
ef90174f JBT |
46 | /* |
47 | * Deferred Registration infrastructure. | |
48 | * | |
49 | * Sometimes watchdog drivers needs to be loaded as soon as possible, | |
50 | * for example when it's impossible to disable it. To do so, | |
51 | * raising the initcall level of the watchdog driver is a solution. | |
52 | * But in such case, the miscdev is maybe not ready (subsys_initcall), and | |
53 | * watchdog_core need miscdev to register the watchdog as a char device. | |
54 | * | |
55 | * The deferred registration infrastructure offer a way for the watchdog | |
56 | * subsystem to register a watchdog properly, even before miscdev is ready. | |
57 | */ | |
58 | ||
59 | static DEFINE_MUTEX(wtd_deferred_reg_mutex); | |
60 | static LIST_HEAD(wtd_deferred_reg_list); | |
61 | static bool wtd_deferred_reg_done; | |
62 | ||
63 | static int watchdog_deferred_registration_add(struct watchdog_device *wdd) | |
64 | { | |
65 | list_add_tail(&wdd->deferred, | |
66 | &wtd_deferred_reg_list); | |
67 | return 0; | |
68 | } | |
69 | ||
70 | static void watchdog_deferred_registration_del(struct watchdog_device *wdd) | |
71 | { | |
72 | struct list_head *p, *n; | |
73 | struct watchdog_device *wdd_tmp; | |
74 | ||
75 | list_for_each_safe(p, n, &wtd_deferred_reg_list) { | |
76 | wdd_tmp = list_entry(p, struct watchdog_device, | |
77 | deferred); | |
78 | if (wdd_tmp == wdd) { | |
79 | list_del(&wdd_tmp->deferred); | |
80 | break; | |
81 | } | |
82 | } | |
83 | } | |
84 | ||
3048253e FP |
85 | static void watchdog_check_min_max_timeout(struct watchdog_device *wdd) |
86 | { | |
87 | /* | |
88 | * Check that we have valid min and max timeout values, if | |
89 | * not reset them both to 0 (=not used or unknown) | |
90 | */ | |
91 | if (wdd->min_timeout > wdd->max_timeout) { | |
92 | pr_info("Invalid min and max timeout values, resetting to 0!\n"); | |
93 | wdd->min_timeout = 0; | |
94 | wdd->max_timeout = 0; | |
95 | } | |
96 | } | |
97 | ||
98 | /** | |
99 | * watchdog_init_timeout() - initialize the timeout field | |
100 | * @timeout_parm: timeout module parameter | |
101 | * @dev: Device that stores the timeout-sec property | |
102 | * | |
103 | * Initialize the timeout field of the watchdog_device struct with either the | |
104 | * timeout module parameter (if it is valid value) or the timeout-sec property | |
105 | * (only if it is a valid value and the timeout_parm is out of bounds). | |
106 | * If none of them are valid then we keep the old value (which should normally | |
107 | * be the default timeout value. | |
108 | * | |
109 | * A zero is returned on success and -EINVAL for failure. | |
110 | */ | |
111 | int watchdog_init_timeout(struct watchdog_device *wdd, | |
112 | unsigned int timeout_parm, struct device *dev) | |
113 | { | |
114 | unsigned int t = 0; | |
115 | int ret = 0; | |
116 | ||
117 | watchdog_check_min_max_timeout(wdd); | |
118 | ||
6ffcff93 | 119 | /* try to get the timeout module parameter first */ |
2c34d599 | 120 | if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) { |
3048253e FP |
121 | wdd->timeout = timeout_parm; |
122 | return ret; | |
123 | } | |
124 | if (timeout_parm) | |
125 | ret = -EINVAL; | |
126 | ||
127 | /* try to get the timeout_sec property */ | |
128 | if (dev == NULL || dev->of_node == NULL) | |
129 | return ret; | |
130 | of_property_read_u32(dev->of_node, "timeout-sec", &t); | |
2c34d599 | 131 | if (!watchdog_timeout_invalid(wdd, t) && t) |
3048253e FP |
132 | wdd->timeout = t; |
133 | else | |
134 | ret = -EINVAL; | |
135 | ||
136 | return ret; | |
137 | } | |
138 | EXPORT_SYMBOL_GPL(watchdog_init_timeout); | |
139 | ||
ef90174f | 140 | static int __watchdog_register_device(struct watchdog_device *wdd) |
43316044 | 141 | { |
d6b469d9 | 142 | int ret, id, devno; |
43316044 WVS |
143 | |
144 | if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL) | |
145 | return -EINVAL; | |
146 | ||
147 | /* Mandatory operations need to be supported */ | |
148 | if (wdd->ops->start == NULL || wdd->ops->stop == NULL) | |
149 | return -EINVAL; | |
150 | ||
3048253e | 151 | watchdog_check_min_max_timeout(wdd); |
3f43f68e | 152 | |
43316044 WVS |
153 | /* |
154 | * Note: now that all watchdog_device data has been verified, we | |
155 | * will not check this anymore in other functions. If data gets | |
156 | * corrupted in a later stage then we expect a kernel panic! | |
157 | */ | |
158 | ||
f4e9c82f | 159 | mutex_init(&wdd->lock); |
45f5fed3 AC |
160 | id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL); |
161 | if (id < 0) | |
162 | return id; | |
163 | wdd->id = id; | |
164 | ||
43316044 WVS |
165 | ret = watchdog_dev_register(wdd); |
166 | if (ret) { | |
45f5fed3 AC |
167 | ida_simple_remove(&watchdog_ida, id); |
168 | if (!(id == 0 && ret == -EBUSY)) | |
169 | return ret; | |
170 | ||
171 | /* Retry in case a legacy watchdog module exists */ | |
172 | id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL); | |
173 | if (id < 0) | |
174 | return id; | |
175 | wdd->id = id; | |
176 | ||
177 | ret = watchdog_dev_register(wdd); | |
178 | if (ret) { | |
179 | ida_simple_remove(&watchdog_ida, id); | |
180 | return ret; | |
181 | } | |
43316044 WVS |
182 | } |
183 | ||
d6b469d9 AC |
184 | devno = wdd->cdev.dev; |
185 | wdd->dev = device_create(watchdog_class, wdd->parent, devno, | |
186 | NULL, "watchdog%d", wdd->id); | |
187 | if (IS_ERR(wdd->dev)) { | |
188 | watchdog_dev_unregister(wdd); | |
189 | ida_simple_remove(&watchdog_ida, id); | |
190 | ret = PTR_ERR(wdd->dev); | |
191 | return ret; | |
192 | } | |
193 | ||
43316044 WVS |
194 | return 0; |
195 | } | |
43316044 WVS |
196 | |
197 | /** | |
ef90174f JBT |
198 | * watchdog_register_device() - register a watchdog device |
199 | * @wdd: watchdog device | |
43316044 | 200 | * |
ef90174f JBT |
201 | * Register a watchdog device with the kernel so that the |
202 | * watchdog timer can be accessed from userspace. | |
203 | * | |
204 | * A zero is returned on success and a negative errno code for | |
205 | * failure. | |
43316044 | 206 | */ |
ef90174f JBT |
207 | |
208 | int watchdog_register_device(struct watchdog_device *wdd) | |
209 | { | |
210 | int ret; | |
211 | ||
212 | mutex_lock(&wtd_deferred_reg_mutex); | |
213 | if (wtd_deferred_reg_done) | |
214 | ret = __watchdog_register_device(wdd); | |
215 | else | |
216 | ret = watchdog_deferred_registration_add(wdd); | |
217 | mutex_unlock(&wtd_deferred_reg_mutex); | |
218 | return ret; | |
219 | } | |
220 | EXPORT_SYMBOL_GPL(watchdog_register_device); | |
221 | ||
222 | static void __watchdog_unregister_device(struct watchdog_device *wdd) | |
43316044 WVS |
223 | { |
224 | int ret; | |
b232a70a | 225 | int devno; |
43316044 WVS |
226 | |
227 | if (wdd == NULL) | |
228 | return; | |
229 | ||
b232a70a | 230 | devno = wdd->cdev.dev; |
43316044 WVS |
231 | ret = watchdog_dev_unregister(wdd); |
232 | if (ret) | |
27c766aa | 233 | pr_err("error unregistering /dev/watchdog (err=%d)\n", ret); |
d6b469d9 | 234 | device_destroy(watchdog_class, devno); |
45f5fed3 | 235 | ida_simple_remove(&watchdog_ida, wdd->id); |
d6b469d9 | 236 | wdd->dev = NULL; |
43316044 | 237 | } |
ef90174f JBT |
238 | |
239 | /** | |
240 | * watchdog_unregister_device() - unregister a watchdog device | |
241 | * @wdd: watchdog device to unregister | |
242 | * | |
243 | * Unregister a watchdog device that was previously successfully | |
244 | * registered with watchdog_register_device(). | |
245 | */ | |
246 | ||
247 | void watchdog_unregister_device(struct watchdog_device *wdd) | |
248 | { | |
249 | mutex_lock(&wtd_deferred_reg_mutex); | |
250 | if (wtd_deferred_reg_done) | |
251 | __watchdog_unregister_device(wdd); | |
252 | else | |
253 | watchdog_deferred_registration_del(wdd); | |
254 | mutex_unlock(&wtd_deferred_reg_mutex); | |
255 | } | |
256 | ||
43316044 WVS |
257 | EXPORT_SYMBOL_GPL(watchdog_unregister_device); |
258 | ||
ef90174f JBT |
259 | static int __init watchdog_deferred_registration(void) |
260 | { | |
261 | mutex_lock(&wtd_deferred_reg_mutex); | |
262 | wtd_deferred_reg_done = true; | |
263 | while (!list_empty(&wtd_deferred_reg_list)) { | |
264 | struct watchdog_device *wdd; | |
265 | ||
266 | wdd = list_first_entry(&wtd_deferred_reg_list, | |
267 | struct watchdog_device, deferred); | |
268 | list_del(&wdd->deferred); | |
269 | __watchdog_register_device(wdd); | |
270 | } | |
271 | mutex_unlock(&wtd_deferred_reg_mutex); | |
272 | return 0; | |
273 | } | |
274 | ||
45f5fed3 AC |
275 | static int __init watchdog_init(void) |
276 | { | |
d6b469d9 AC |
277 | int err; |
278 | ||
279 | watchdog_class = class_create(THIS_MODULE, "watchdog"); | |
280 | if (IS_ERR(watchdog_class)) { | |
281 | pr_err("couldn't create class\n"); | |
282 | return PTR_ERR(watchdog_class); | |
283 | } | |
284 | ||
285 | err = watchdog_dev_init(); | |
286 | if (err < 0) { | |
287 | class_destroy(watchdog_class); | |
288 | return err; | |
289 | } | |
290 | ||
ef90174f | 291 | watchdog_deferred_registration(); |
d6b469d9 | 292 | return 0; |
45f5fed3 AC |
293 | } |
294 | ||
295 | static void __exit watchdog_exit(void) | |
296 | { | |
297 | watchdog_dev_exit(); | |
d6b469d9 | 298 | class_destroy(watchdog_class); |
45f5fed3 AC |
299 | ida_destroy(&watchdog_ida); |
300 | } | |
301 | ||
ef90174f | 302 | subsys_initcall_sync(watchdog_init); |
45f5fed3 AC |
303 | module_exit(watchdog_exit); |
304 | ||
43316044 WVS |
305 | MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>"); |
306 | MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>"); | |
307 | MODULE_DESCRIPTION("WatchDog Timer Driver Core"); | |
308 | MODULE_LICENSE("GPL"); |