blob: 3796434991faa83466c85c8779a072db1278ef33 [file] [log] [blame]
Wim Van Sebroeck43316042011-07-22 18:55:18 +00001/*
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/... */
Alan Cox45f5fed2012-05-10 21:48:59 +020037#include <linux/idr.h> /* For ida_* macros */
Alan Coxd6b469d2012-05-11 12:00:20 +020038#include <linux/err.h> /* For IS_ERR macros */
Wim Van Sebroeck43316042011-07-22 18:55:18 +000039
Wim Van Sebroeck6cfb5aa2012-05-21 15:31:06 +020040#include "watchdog_core.h" /* For watchdog_dev_register/... */
Wim Van Sebroeck43316042011-07-22 18:55:18 +000041
Alan Cox45f5fed2012-05-10 21:48:59 +020042static DEFINE_IDA(watchdog_ida);
Alan Coxd6b469d2012-05-11 12:00:20 +020043static struct class *watchdog_class;
Alan Cox45f5fed2012-05-10 21:48:59 +020044
Wim Van Sebroeck43316042011-07-22 18:55:18 +000045/**
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{
Alan Coxd6b469d2012-05-11 12:00:20 +020057 int ret, id, devno;
Wim Van Sebroeck43316042011-07-22 18:55:18 +000058
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 /*
Wim Van Sebroeck3f43f682011-07-22 19:00:16 +000067 * 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 /*
Wim Van Sebroeck43316042011-07-22 18:55:18 +000077 * 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
Hans de Goedef4e9c822012-05-22 11:40:26 +020082 mutex_init(&wdd->lock);
Alan Cox45f5fed2012-05-10 21:48:59 +020083 id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
84 if (id < 0)
85 return id;
86 wdd->id = id;
87
Wim Van Sebroeck43316042011-07-22 18:55:18 +000088 ret = watchdog_dev_register(wdd);
89 if (ret) {
Alan Cox45f5fed2012-05-10 21:48:59 +020090 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 }
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000105 }
106
Alan Coxd6b469d2012-05-11 12:00:20 +0200107 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
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000117 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;
Wei Yongjunb232a702012-09-10 12:41:15 +0800131 int devno;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000132
133 if (wdd == NULL)
134 return;
135
Wei Yongjunb232a702012-09-10 12:41:15 +0800136 devno = wdd->cdev.dev;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000137 ret = watchdog_dev_unregister(wdd);
138 if (ret)
Joe Perches27c766a2012-02-15 15:06:19 -0800139 pr_err("error unregistering /dev/watchdog (err=%d)\n", ret);
Alan Coxd6b469d2012-05-11 12:00:20 +0200140 device_destroy(watchdog_class, devno);
Alan Cox45f5fed2012-05-10 21:48:59 +0200141 ida_simple_remove(&watchdog_ida, wdd->id);
Alan Coxd6b469d2012-05-11 12:00:20 +0200142 wdd->dev = NULL;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000143}
144EXPORT_SYMBOL_GPL(watchdog_unregister_device);
145
Alan Cox45f5fed2012-05-10 21:48:59 +0200146static int __init watchdog_init(void)
147{
Alan Coxd6b469d2012-05-11 12:00:20 +0200148 int err;
149
150 watchdog_class = class_create(THIS_MODULE, "watchdog");
151 if (IS_ERR(watchdog_class)) {
152 pr_err("couldn't create class\n");
153 return PTR_ERR(watchdog_class);
154 }
155
156 err = watchdog_dev_init();
157 if (err < 0) {
158 class_destroy(watchdog_class);
159 return err;
160 }
161
162 return 0;
Alan Cox45f5fed2012-05-10 21:48:59 +0200163}
164
165static void __exit watchdog_exit(void)
166{
167 watchdog_dev_exit();
Alan Coxd6b469d2012-05-11 12:00:20 +0200168 class_destroy(watchdog_class);
Alan Cox45f5fed2012-05-10 21:48:59 +0200169 ida_destroy(&watchdog_ida);
170}
171
172subsys_initcall(watchdog_init);
173module_exit(watchdog_exit);
174
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000175MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
176MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
177MODULE_DESCRIPTION("WatchDog Timer Driver Core");
178MODULE_LICENSE("GPL");