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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/... */ | |
37 | ||
38 | #include "watchdog_dev.h" /* For watchdog_dev_register/... */ | |
39 | ||
40 | /** | |
41 | * watchdog_register_device() - register a watchdog device | |
42 | * @wdd: watchdog device | |
43 | * | |
44 | * Register a watchdog device with the kernel so that the | |
45 | * watchdog timer can be accessed from userspace. | |
46 | * | |
47 | * A zero is returned on success and a negative errno code for | |
48 | * failure. | |
49 | */ | |
50 | int watchdog_register_device(struct watchdog_device *wdd) | |
51 | { | |
52 | int ret; | |
53 | ||
54 | if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL) | |
55 | return -EINVAL; | |
56 | ||
57 | /* Mandatory operations need to be supported */ | |
58 | if (wdd->ops->start == NULL || wdd->ops->stop == NULL) | |
59 | return -EINVAL; | |
60 | ||
3f43f68e WVS |
61 | /* |
62 | * Check that we have valid min and max timeout values, if | |
63 | * not reset them both to 0 (=not used or unknown) | |
64 | */ | |
65 | if (wdd->min_timeout > wdd->max_timeout) { | |
66 | pr_info("Invalid min and max timeout values, resetting to 0!\n"); | |
67 | wdd->min_timeout = 0; | |
68 | wdd->max_timeout = 0; | |
69 | } | |
70 | ||
43316044 WVS |
71 | /* |
72 | * Note: now that all watchdog_device data has been verified, we | |
73 | * will not check this anymore in other functions. If data gets | |
74 | * corrupted in a later stage then we expect a kernel panic! | |
75 | */ | |
76 | ||
77 | /* We only support 1 watchdog device via the /dev/watchdog interface */ | |
78 | ret = watchdog_dev_register(wdd); | |
79 | if (ret) { | |
80 | pr_err("error registering /dev/watchdog (err=%d).\n", ret); | |
81 | return ret; | |
82 | } | |
83 | ||
84 | return 0; | |
85 | } | |
86 | EXPORT_SYMBOL_GPL(watchdog_register_device); | |
87 | ||
88 | /** | |
89 | * watchdog_unregister_device() - unregister a watchdog device | |
90 | * @wdd: watchdog device to unregister | |
91 | * | |
92 | * Unregister a watchdog device that was previously successfully | |
93 | * registered with watchdog_register_device(). | |
94 | */ | |
95 | void watchdog_unregister_device(struct watchdog_device *wdd) | |
96 | { | |
97 | int ret; | |
98 | ||
99 | if (wdd == NULL) | |
100 | return; | |
101 | ||
102 | ret = watchdog_dev_unregister(wdd); | |
103 | if (ret) | |
104 | pr_err("error unregistering /dev/watchdog (err=%d).\n", ret); | |
105 | } | |
106 | EXPORT_SYMBOL_GPL(watchdog_unregister_device); | |
107 | ||
108 | MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>"); | |
109 | MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>"); | |
110 | MODULE_DESCRIPTION("WatchDog Timer Driver Core"); | |
111 | MODULE_LICENSE("GPL"); |