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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 | |
3048253e FP |
46 | static void watchdog_check_min_max_timeout(struct watchdog_device *wdd) |
47 | { | |
48 | /* | |
49 | * Check that we have valid min and max timeout values, if | |
50 | * not reset them both to 0 (=not used or unknown) | |
51 | */ | |
52 | if (wdd->min_timeout > wdd->max_timeout) { | |
53 | pr_info("Invalid min and max timeout values, resetting to 0!\n"); | |
54 | wdd->min_timeout = 0; | |
55 | wdd->max_timeout = 0; | |
56 | } | |
57 | } | |
58 | ||
59 | /** | |
60 | * watchdog_init_timeout() - initialize the timeout field | |
61 | * @timeout_parm: timeout module parameter | |
62 | * @dev: Device that stores the timeout-sec property | |
63 | * | |
64 | * Initialize the timeout field of the watchdog_device struct with either the | |
65 | * timeout module parameter (if it is valid value) or the timeout-sec property | |
66 | * (only if it is a valid value and the timeout_parm is out of bounds). | |
67 | * If none of them are valid then we keep the old value (which should normally | |
68 | * be the default timeout value. | |
69 | * | |
70 | * A zero is returned on success and -EINVAL for failure. | |
71 | */ | |
72 | int watchdog_init_timeout(struct watchdog_device *wdd, | |
73 | unsigned int timeout_parm, struct device *dev) | |
74 | { | |
75 | unsigned int t = 0; | |
76 | int ret = 0; | |
77 | ||
78 | watchdog_check_min_max_timeout(wdd); | |
79 | ||
80 | /* try to get the tiemout module parameter first */ | |
81 | if (!watchdog_timeout_invalid(wdd, timeout_parm)) { | |
82 | wdd->timeout = timeout_parm; | |
83 | return ret; | |
84 | } | |
85 | if (timeout_parm) | |
86 | ret = -EINVAL; | |
87 | ||
88 | /* try to get the timeout_sec property */ | |
89 | if (dev == NULL || dev->of_node == NULL) | |
90 | return ret; | |
91 | of_property_read_u32(dev->of_node, "timeout-sec", &t); | |
92 | if (!watchdog_timeout_invalid(wdd, t)) | |
93 | wdd->timeout = t; | |
94 | else | |
95 | ret = -EINVAL; | |
96 | ||
97 | return ret; | |
98 | } | |
99 | EXPORT_SYMBOL_GPL(watchdog_init_timeout); | |
100 | ||
43316044 WVS |
101 | /** |
102 | * watchdog_register_device() - register a watchdog device | |
103 | * @wdd: watchdog device | |
104 | * | |
105 | * Register a watchdog device with the kernel so that the | |
106 | * watchdog timer can be accessed from userspace. | |
107 | * | |
108 | * A zero is returned on success and a negative errno code for | |
109 | * failure. | |
110 | */ | |
111 | int watchdog_register_device(struct watchdog_device *wdd) | |
112 | { | |
d6b469d9 | 113 | int ret, id, devno; |
43316044 WVS |
114 | |
115 | if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL) | |
116 | return -EINVAL; | |
117 | ||
118 | /* Mandatory operations need to be supported */ | |
119 | if (wdd->ops->start == NULL || wdd->ops->stop == NULL) | |
120 | return -EINVAL; | |
121 | ||
3048253e | 122 | watchdog_check_min_max_timeout(wdd); |
3f43f68e | 123 | |
43316044 WVS |
124 | /* |
125 | * Note: now that all watchdog_device data has been verified, we | |
126 | * will not check this anymore in other functions. If data gets | |
127 | * corrupted in a later stage then we expect a kernel panic! | |
128 | */ | |
129 | ||
f4e9c82f | 130 | mutex_init(&wdd->lock); |
45f5fed3 AC |
131 | id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL); |
132 | if (id < 0) | |
133 | return id; | |
134 | wdd->id = id; | |
135 | ||
43316044 WVS |
136 | ret = watchdog_dev_register(wdd); |
137 | if (ret) { | |
45f5fed3 AC |
138 | ida_simple_remove(&watchdog_ida, id); |
139 | if (!(id == 0 && ret == -EBUSY)) | |
140 | return ret; | |
141 | ||
142 | /* Retry in case a legacy watchdog module exists */ | |
143 | id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL); | |
144 | if (id < 0) | |
145 | return id; | |
146 | wdd->id = id; | |
147 | ||
148 | ret = watchdog_dev_register(wdd); | |
149 | if (ret) { | |
150 | ida_simple_remove(&watchdog_ida, id); | |
151 | return ret; | |
152 | } | |
43316044 WVS |
153 | } |
154 | ||
d6b469d9 AC |
155 | devno = wdd->cdev.dev; |
156 | wdd->dev = device_create(watchdog_class, wdd->parent, devno, | |
157 | NULL, "watchdog%d", wdd->id); | |
158 | if (IS_ERR(wdd->dev)) { | |
159 | watchdog_dev_unregister(wdd); | |
160 | ida_simple_remove(&watchdog_ida, id); | |
161 | ret = PTR_ERR(wdd->dev); | |
162 | return ret; | |
163 | } | |
164 | ||
43316044 WVS |
165 | return 0; |
166 | } | |
167 | EXPORT_SYMBOL_GPL(watchdog_register_device); | |
168 | ||
169 | /** | |
170 | * watchdog_unregister_device() - unregister a watchdog device | |
171 | * @wdd: watchdog device to unregister | |
172 | * | |
173 | * Unregister a watchdog device that was previously successfully | |
174 | * registered with watchdog_register_device(). | |
175 | */ | |
176 | void watchdog_unregister_device(struct watchdog_device *wdd) | |
177 | { | |
178 | int ret; | |
b232a70a | 179 | int devno; |
43316044 WVS |
180 | |
181 | if (wdd == NULL) | |
182 | return; | |
183 | ||
b232a70a | 184 | devno = wdd->cdev.dev; |
43316044 WVS |
185 | ret = watchdog_dev_unregister(wdd); |
186 | if (ret) | |
27c766aa | 187 | pr_err("error unregistering /dev/watchdog (err=%d)\n", ret); |
d6b469d9 | 188 | device_destroy(watchdog_class, devno); |
45f5fed3 | 189 | ida_simple_remove(&watchdog_ida, wdd->id); |
d6b469d9 | 190 | wdd->dev = NULL; |
43316044 WVS |
191 | } |
192 | EXPORT_SYMBOL_GPL(watchdog_unregister_device); | |
193 | ||
45f5fed3 AC |
194 | static int __init watchdog_init(void) |
195 | { | |
d6b469d9 AC |
196 | int err; |
197 | ||
198 | watchdog_class = class_create(THIS_MODULE, "watchdog"); | |
199 | if (IS_ERR(watchdog_class)) { | |
200 | pr_err("couldn't create class\n"); | |
201 | return PTR_ERR(watchdog_class); | |
202 | } | |
203 | ||
204 | err = watchdog_dev_init(); | |
205 | if (err < 0) { | |
206 | class_destroy(watchdog_class); | |
207 | return err; | |
208 | } | |
209 | ||
210 | return 0; | |
45f5fed3 AC |
211 | } |
212 | ||
213 | static void __exit watchdog_exit(void) | |
214 | { | |
215 | watchdog_dev_exit(); | |
d6b469d9 | 216 | class_destroy(watchdog_class); |
45f5fed3 AC |
217 | ida_destroy(&watchdog_ida); |
218 | } | |
219 | ||
220 | subsys_initcall(watchdog_init); | |
221 | module_exit(watchdog_exit); | |
222 | ||
43316044 WVS |
223 | MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>"); |
224 | MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>"); | |
225 | MODULE_DESCRIPTION("WatchDog Timer Driver Core"); | |
226 | MODULE_LICENSE("GPL"); |