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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 */
Fabio Porcedda30482532013-01-08 11:04:10 +010039#include <linux/of.h> /* For of_get_timeout_sec */
Wim Van Sebroeck43316042011-07-22 18:55:18 +000040
Wim Van Sebroeck6cfb5aa2012-05-21 15:31:06 +020041#include "watchdog_core.h" /* For watchdog_dev_register/... */
Wim Van Sebroeck43316042011-07-22 18:55:18 +000042
Alan Cox45f5fed2012-05-10 21:48:59 +020043static DEFINE_IDA(watchdog_ida);
Alan Coxd6b469d2012-05-11 12:00:20 +020044static struct class *watchdog_class;
Alan Cox45f5fed2012-05-10 21:48:59 +020045
Jean-Baptiste Theouef901742015-06-09 09:55:02 -070046/*
47 * Deferred Registration infrastructure.
48 *
49 * Sometimes watchdog drivers needs to be loaded as soon as possible,
50 * for example when it's impossible to disable it. To do so,
51 * raising the initcall level of the watchdog driver is a solution.
52 * But in such case, the miscdev is maybe not ready (subsys_initcall), and
53 * watchdog_core need miscdev to register the watchdog as a char device.
54 *
55 * The deferred registration infrastructure offer a way for the watchdog
56 * subsystem to register a watchdog properly, even before miscdev is ready.
57 */
58
59static DEFINE_MUTEX(wtd_deferred_reg_mutex);
60static LIST_HEAD(wtd_deferred_reg_list);
61static bool wtd_deferred_reg_done;
62
63static int watchdog_deferred_registration_add(struct watchdog_device *wdd)
64{
65 list_add_tail(&wdd->deferred,
66 &wtd_deferred_reg_list);
67 return 0;
68}
69
70static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
71{
72 struct list_head *p, *n;
73 struct watchdog_device *wdd_tmp;
74
75 list_for_each_safe(p, n, &wtd_deferred_reg_list) {
76 wdd_tmp = list_entry(p, struct watchdog_device,
77 deferred);
78 if (wdd_tmp == wdd) {
79 list_del(&wdd_tmp->deferred);
80 break;
81 }
82 }
83}
84
Fabio Porcedda30482532013-01-08 11:04:10 +010085static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
86{
87 /*
88 * Check that we have valid min and max timeout values, if
89 * not reset them both to 0 (=not used or unknown)
90 */
91 if (wdd->min_timeout > wdd->max_timeout) {
92 pr_info("Invalid min and max timeout values, resetting to 0!\n");
93 wdd->min_timeout = 0;
94 wdd->max_timeout = 0;
95 }
96}
97
98/**
99 * watchdog_init_timeout() - initialize the timeout field
100 * @timeout_parm: timeout module parameter
101 * @dev: Device that stores the timeout-sec property
102 *
103 * Initialize the timeout field of the watchdog_device struct with either the
104 * timeout module parameter (if it is valid value) or the timeout-sec property
105 * (only if it is a valid value and the timeout_parm is out of bounds).
106 * If none of them are valid then we keep the old value (which should normally
107 * be the default timeout value.
108 *
109 * A zero is returned on success and -EINVAL for failure.
110 */
111int watchdog_init_timeout(struct watchdog_device *wdd,
112 unsigned int timeout_parm, struct device *dev)
113{
114 unsigned int t = 0;
115 int ret = 0;
116
117 watchdog_check_min_max_timeout(wdd);
118
Sachin Kamat6ffcff92013-10-28 14:17:17 +0530119 /* try to get the timeout module parameter first */
Doug Anderson2c34d592013-11-26 10:22:52 -0800120 if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
Fabio Porcedda30482532013-01-08 11:04:10 +0100121 wdd->timeout = timeout_parm;
122 return ret;
123 }
124 if (timeout_parm)
125 ret = -EINVAL;
126
127 /* try to get the timeout_sec property */
128 if (dev == NULL || dev->of_node == NULL)
129 return ret;
130 of_property_read_u32(dev->of_node, "timeout-sec", &t);
Doug Anderson2c34d592013-11-26 10:22:52 -0800131 if (!watchdog_timeout_invalid(wdd, t) && t)
Fabio Porcedda30482532013-01-08 11:04:10 +0100132 wdd->timeout = t;
133 else
134 ret = -EINVAL;
135
136 return ret;
137}
138EXPORT_SYMBOL_GPL(watchdog_init_timeout);
139
Jean-Baptiste Theouef901742015-06-09 09:55:02 -0700140static int __watchdog_register_device(struct watchdog_device *wdd)
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000141{
Justin Chen9dd4e172015-09-02 11:00:17 -0700142 int ret, id = -1, devno;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000143
144 if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
145 return -EINVAL;
146
147 /* Mandatory operations need to be supported */
148 if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
149 return -EINVAL;
150
Fabio Porcedda30482532013-01-08 11:04:10 +0100151 watchdog_check_min_max_timeout(wdd);
Wim Van Sebroeck3f43f682011-07-22 19:00:16 +0000152
153 /*
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000154 * Note: now that all watchdog_device data has been verified, we
155 * will not check this anymore in other functions. If data gets
156 * corrupted in a later stage then we expect a kernel panic!
157 */
158
Hans de Goedef4e9c822012-05-22 11:40:26 +0200159 mutex_init(&wdd->lock);
Justin Chen9dd4e172015-09-02 11:00:17 -0700160
161 /* Use alias for watchdog id if possible */
162 if (wdd->parent) {
163 ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
164 if (ret >= 0)
165 id = ida_simple_get(&watchdog_ida, ret,
166 ret + 1, GFP_KERNEL);
167 }
168
169 if (id < 0)
170 id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
171
Alan Cox45f5fed2012-05-10 21:48:59 +0200172 if (id < 0)
173 return id;
174 wdd->id = id;
175
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000176 ret = watchdog_dev_register(wdd);
177 if (ret) {
Alan Cox45f5fed2012-05-10 21:48:59 +0200178 ida_simple_remove(&watchdog_ida, id);
179 if (!(id == 0 && ret == -EBUSY))
180 return ret;
181
182 /* Retry in case a legacy watchdog module exists */
183 id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
184 if (id < 0)
185 return id;
186 wdd->id = id;
187
188 ret = watchdog_dev_register(wdd);
189 if (ret) {
190 ida_simple_remove(&watchdog_ida, id);
191 return ret;
192 }
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000193 }
194
Alan Coxd6b469d2012-05-11 12:00:20 +0200195 devno = wdd->cdev.dev;
196 wdd->dev = device_create(watchdog_class, wdd->parent, devno,
197 NULL, "watchdog%d", wdd->id);
198 if (IS_ERR(wdd->dev)) {
199 watchdog_dev_unregister(wdd);
200 ida_simple_remove(&watchdog_ida, id);
201 ret = PTR_ERR(wdd->dev);
202 return ret;
203 }
204
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000205 return 0;
206}
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000207
208/**
Jean-Baptiste Theouef901742015-06-09 09:55:02 -0700209 * watchdog_register_device() - register a watchdog device
210 * @wdd: watchdog device
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000211 *
Jean-Baptiste Theouef901742015-06-09 09:55:02 -0700212 * Register a watchdog device with the kernel so that the
213 * watchdog timer can be accessed from userspace.
214 *
215 * A zero is returned on success and a negative errno code for
216 * failure.
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000217 */
Jean-Baptiste Theouef901742015-06-09 09:55:02 -0700218
219int watchdog_register_device(struct watchdog_device *wdd)
220{
221 int ret;
222
223 mutex_lock(&wtd_deferred_reg_mutex);
224 if (wtd_deferred_reg_done)
225 ret = __watchdog_register_device(wdd);
226 else
227 ret = watchdog_deferred_registration_add(wdd);
228 mutex_unlock(&wtd_deferred_reg_mutex);
229 return ret;
230}
231EXPORT_SYMBOL_GPL(watchdog_register_device);
232
233static void __watchdog_unregister_device(struct watchdog_device *wdd)
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000234{
235 int ret;
Wei Yongjunb232a702012-09-10 12:41:15 +0800236 int devno;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000237
238 if (wdd == NULL)
239 return;
240
Wei Yongjunb232a702012-09-10 12:41:15 +0800241 devno = wdd->cdev.dev;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000242 ret = watchdog_dev_unregister(wdd);
243 if (ret)
Joe Perches27c766a2012-02-15 15:06:19 -0800244 pr_err("error unregistering /dev/watchdog (err=%d)\n", ret);
Alan Coxd6b469d2012-05-11 12:00:20 +0200245 device_destroy(watchdog_class, devno);
Alan Cox45f5fed2012-05-10 21:48:59 +0200246 ida_simple_remove(&watchdog_ida, wdd->id);
Alan Coxd6b469d2012-05-11 12:00:20 +0200247 wdd->dev = NULL;
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000248}
Jean-Baptiste Theouef901742015-06-09 09:55:02 -0700249
250/**
251 * watchdog_unregister_device() - unregister a watchdog device
252 * @wdd: watchdog device to unregister
253 *
254 * Unregister a watchdog device that was previously successfully
255 * registered with watchdog_register_device().
256 */
257
258void watchdog_unregister_device(struct watchdog_device *wdd)
259{
260 mutex_lock(&wtd_deferred_reg_mutex);
261 if (wtd_deferred_reg_done)
262 __watchdog_unregister_device(wdd);
263 else
264 watchdog_deferred_registration_del(wdd);
265 mutex_unlock(&wtd_deferred_reg_mutex);
266}
267
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000268EXPORT_SYMBOL_GPL(watchdog_unregister_device);
269
Jean-Baptiste Theouef901742015-06-09 09:55:02 -0700270static int __init watchdog_deferred_registration(void)
271{
272 mutex_lock(&wtd_deferred_reg_mutex);
273 wtd_deferred_reg_done = true;
274 while (!list_empty(&wtd_deferred_reg_list)) {
275 struct watchdog_device *wdd;
276
277 wdd = list_first_entry(&wtd_deferred_reg_list,
278 struct watchdog_device, deferred);
279 list_del(&wdd->deferred);
280 __watchdog_register_device(wdd);
281 }
282 mutex_unlock(&wtd_deferred_reg_mutex);
283 return 0;
284}
285
Alan Cox45f5fed2012-05-10 21:48:59 +0200286static int __init watchdog_init(void)
287{
Alan Coxd6b469d2012-05-11 12:00:20 +0200288 int err;
289
290 watchdog_class = class_create(THIS_MODULE, "watchdog");
291 if (IS_ERR(watchdog_class)) {
292 pr_err("couldn't create class\n");
293 return PTR_ERR(watchdog_class);
294 }
295
296 err = watchdog_dev_init();
297 if (err < 0) {
298 class_destroy(watchdog_class);
299 return err;
300 }
301
Jean-Baptiste Theouef901742015-06-09 09:55:02 -0700302 watchdog_deferred_registration();
Alan Coxd6b469d2012-05-11 12:00:20 +0200303 return 0;
Alan Cox45f5fed2012-05-10 21:48:59 +0200304}
305
306static void __exit watchdog_exit(void)
307{
308 watchdog_dev_exit();
Alan Coxd6b469d2012-05-11 12:00:20 +0200309 class_destroy(watchdog_class);
Alan Cox45f5fed2012-05-10 21:48:59 +0200310 ida_destroy(&watchdog_ida);
311}
312
Jean-Baptiste Theouef901742015-06-09 09:55:02 -0700313subsys_initcall_sync(watchdog_init);
Alan Cox45f5fed2012-05-10 21:48:59 +0200314module_exit(watchdog_exit);
315
Wim Van Sebroeck43316042011-07-22 18:55:18 +0000316MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
317MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
318MODULE_DESCRIPTION("WatchDog Timer Driver Core");
319MODULE_LICENSE("GPL");