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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/... */ |
37 | #include <linux/idr.h> /* For ida_* macros */ |
38 | #include <linux/err.h> /* For IS_ERR macros */ |
39 | #include <linux/of.h> /* For of_get_timeout_sec */ |
40 | |
41 | #include "watchdog_core.h" /* For watchdog_dev_register/... */ |
42 | |
43 | static DEFINE_IDA(watchdog_ida); |
44 | static struct class *watchdog_class; |
45 | |
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 | |
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 | { |
113 | int ret, id, devno; |
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 | |
122 | watchdog_check_min_max_timeout(wdd); |
123 | |
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 | |
130 | mutex_init(&wdd->lock); |
131 | id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL); |
132 | if (id < 0) |
133 | return id; |
134 | wdd->id = id; |
135 | |
136 | ret = watchdog_dev_register(wdd); |
137 | if (ret) { |
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 | } |
153 | } |
154 | |
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 | |
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; |
179 | int devno; |
180 | |
181 | if (wdd == NULL) |
182 | return; |
183 | |
184 | devno = wdd->cdev.dev; |
185 | ret = watchdog_dev_unregister(wdd); |
186 | if (ret) |
187 | pr_err("error unregistering /dev/watchdog (err=%d)\n", ret); |
188 | device_destroy(watchdog_class, devno); |
189 | ida_simple_remove(&watchdog_ida, wdd->id); |
190 | wdd->dev = NULL; |
191 | } |
192 | EXPORT_SYMBOL_GPL(watchdog_unregister_device); |
193 | |
194 | static int __init watchdog_init(void) |
195 | { |
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; |
211 | } |
212 | |
213 | static void __exit watchdog_exit(void) |
214 | { |
215 | watchdog_dev_exit(); |
216 | class_destroy(watchdog_class); |
217 | ida_destroy(&watchdog_ida); |
218 | } |
219 | |
220 | subsys_initcall(watchdog_init); |
221 | module_exit(watchdog_exit); |
222 | |
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"); |
227 |
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