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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
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 */
50int 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
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
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}
86EXPORT_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 */
95void 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}
106EXPORT_SYMBOL_GPL(watchdog_unregister_device);
107
108MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
109MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
110MODULE_DESCRIPTION("WatchDog Timer Driver Core");
111MODULE_LICENSE("GPL");
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
40#include "watchdog_core.h" /* For watchdog_dev_register/... */
41
42static DEFINE_IDA(watchdog_ida);
43static struct class *watchdog_class;
44
45/**
46 * watchdog_register_device() - register a watchdog device
47 * @wdd: watchdog device
48 *
49 * Register a watchdog device with the kernel so that the
50 * watchdog timer can be accessed from userspace.
51 *
52 * A zero is returned on success and a negative errno code for
53 * failure.
54 */
55int watchdog_register_device(struct watchdog_device *wdd)
56{
57 int ret, id, devno;
58
59 if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
60 return -EINVAL;
61
62 /* Mandatory operations need to be supported */
63 if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
64 return -EINVAL;
65
66 /*
67 * Check that we have valid min and max timeout values, if
68 * not reset them both to 0 (=not used or unknown)
69 */
70 if (wdd->min_timeout > wdd->max_timeout) {
71 pr_info("Invalid min and max timeout values, resetting to 0!\n");
72 wdd->min_timeout = 0;
73 wdd->max_timeout = 0;
74 }
75
76 /*
77 * Note: now that all watchdog_device data has been verified, we
78 * will not check this anymore in other functions. If data gets
79 * corrupted in a later stage then we expect a kernel panic!
80 */
81
82 mutex_init(&wdd->lock);
83 id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
84 if (id < 0)
85 return id;
86 wdd->id = id;
87
88 ret = watchdog_dev_register(wdd);
89 if (ret) {
90 ida_simple_remove(&watchdog_ida, id);
91 if (!(id == 0 && ret == -EBUSY))
92 return ret;
93
94 /* Retry in case a legacy watchdog module exists */
95 id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
96 if (id < 0)
97 return id;
98 wdd->id = id;
99
100 ret = watchdog_dev_register(wdd);
101 if (ret) {
102 ida_simple_remove(&watchdog_ida, id);
103 return ret;
104 }
105 }
106
107 devno = wdd->cdev.dev;
108 wdd->dev = device_create(watchdog_class, wdd->parent, devno,
109 NULL, "watchdog%d", wdd->id);
110 if (IS_ERR(wdd->dev)) {
111 watchdog_dev_unregister(wdd);
112 ida_simple_remove(&watchdog_ida, id);
113 ret = PTR_ERR(wdd->dev);
114 return ret;
115 }
116
117 return 0;
118}
119EXPORT_SYMBOL_GPL(watchdog_register_device);
120
121/**
122 * watchdog_unregister_device() - unregister a watchdog device
123 * @wdd: watchdog device to unregister
124 *
125 * Unregister a watchdog device that was previously successfully
126 * registered with watchdog_register_device().
127 */
128void watchdog_unregister_device(struct watchdog_device *wdd)
129{
130 int ret;
131 int devno = wdd->cdev.dev;
132
133 if (wdd == NULL)
134 return;
135
136 ret = watchdog_dev_unregister(wdd);
137 if (ret)
138 pr_err("error unregistering /dev/watchdog (err=%d)\n", ret);
139 device_destroy(watchdog_class, devno);
140 ida_simple_remove(&watchdog_ida, wdd->id);
141 wdd->dev = NULL;
142}
143EXPORT_SYMBOL_GPL(watchdog_unregister_device);
144
145static int __init watchdog_init(void)
146{
147 int err;
148
149 watchdog_class = class_create(THIS_MODULE, "watchdog");
150 if (IS_ERR(watchdog_class)) {
151 pr_err("couldn't create class\n");
152 return PTR_ERR(watchdog_class);
153 }
154
155 err = watchdog_dev_init();
156 if (err < 0) {
157 class_destroy(watchdog_class);
158 return err;
159 }
160
161 return 0;
162}
163
164static void __exit watchdog_exit(void)
165{
166 watchdog_dev_exit();
167 class_destroy(watchdog_class);
168 ida_destroy(&watchdog_ida);
169}
170
171subsys_initcall(watchdog_init);
172module_exit(watchdog_exit);
173
174MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
175MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
176MODULE_DESCRIPTION("WatchDog Timer Driver Core");
177MODULE_LICENSE("GPL");