[PATCH] Remove useless check in drivers/net/pcmcia/xirc2ps_cs.c
[linux-2.6] / drivers / leds / led-triggers.c
1 /*
2  * LED Triggers Core
3  *
4  * Copyright 2005-2006 Openedhand Ltd.
5  *
6  * Author: Richard Purdie <rpurdie@openedhand.com>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  *
12  */
13
14 #include <linux/config.h>
15 #include <linux/module.h>
16 #include <linux/kernel.h>
17 #include <linux/init.h>
18 #include <linux/list.h>
19 #include <linux/spinlock.h>
20 #include <linux/device.h>
21 #include <linux/sysdev.h>
22 #include <linux/timer.h>
23 #include <linux/leds.h>
24 #include "leds.h"
25
26 /*
27  * Nests outside led_cdev->trigger_lock
28  */
29 static rwlock_t triggers_list_lock = RW_LOCK_UNLOCKED;
30 static LIST_HEAD(trigger_list);
31
32 ssize_t led_trigger_store(struct class_device *dev, const char *buf,
33                         size_t count)
34 {
35         struct led_classdev *led_cdev = class_get_devdata(dev);
36         char trigger_name[TRIG_NAME_MAX];
37         struct led_trigger *trig;
38         size_t len;
39
40         trigger_name[sizeof(trigger_name) - 1] = '\0';
41         strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
42         len = strlen(trigger_name);
43
44         if (len && trigger_name[len - 1] == '\n')
45                 trigger_name[len - 1] = '\0';
46
47         if (!strcmp(trigger_name, "none")) {
48                 write_lock(&led_cdev->trigger_lock);
49                 led_trigger_set(led_cdev, NULL);
50                 write_unlock(&led_cdev->trigger_lock);
51                 return count;
52         }
53
54         read_lock(&triggers_list_lock);
55         list_for_each_entry(trig, &trigger_list, next_trig) {
56                 if (!strcmp(trigger_name, trig->name)) {
57                         write_lock(&led_cdev->trigger_lock);
58                         led_trigger_set(led_cdev, trig);
59                         write_unlock(&led_cdev->trigger_lock);
60
61                         read_unlock(&triggers_list_lock);
62                         return count;
63                 }
64         }
65         read_unlock(&triggers_list_lock);
66
67         return -EINVAL;
68 }
69
70
71 ssize_t led_trigger_show(struct class_device *dev, char *buf)
72 {
73         struct led_classdev *led_cdev = class_get_devdata(dev);
74         struct led_trigger *trig;
75         int len = 0;
76
77         read_lock(&triggers_list_lock);
78         read_lock(&led_cdev->trigger_lock);
79
80         if (!led_cdev->trigger)
81                 len += sprintf(buf+len, "[none] ");
82         else
83                 len += sprintf(buf+len, "none ");
84
85         list_for_each_entry(trig, &trigger_list, next_trig) {
86                 if (led_cdev->trigger && !strcmp(led_cdev->trigger->name,
87                                                         trig->name))
88                         len += sprintf(buf+len, "[%s] ", trig->name);
89                 else
90                         len += sprintf(buf+len, "%s ", trig->name);
91         }
92         read_unlock(&led_cdev->trigger_lock);
93         read_unlock(&triggers_list_lock);
94
95         len += sprintf(len+buf, "\n");
96         return len;
97 }
98
99 void led_trigger_event(struct led_trigger *trigger,
100                         enum led_brightness brightness)
101 {
102         struct list_head *entry;
103
104         if (!trigger)
105                 return;
106
107         read_lock(&trigger->leddev_list_lock);
108         list_for_each(entry, &trigger->led_cdevs) {
109                 struct led_classdev *led_cdev;
110
111                 led_cdev = list_entry(entry, struct led_classdev, trig_list);
112                 led_set_brightness(led_cdev, brightness);
113         }
114         read_unlock(&trigger->leddev_list_lock);
115 }
116
117 /* Caller must ensure led_cdev->trigger_lock held */
118 void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trigger)
119 {
120         unsigned long flags;
121
122         /* Remove any existing trigger */
123         if (led_cdev->trigger) {
124                 write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
125                 list_del(&led_cdev->trig_list);
126                 write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock, flags);
127                 if (led_cdev->trigger->deactivate)
128                         led_cdev->trigger->deactivate(led_cdev);
129         }
130         if (trigger) {
131                 write_lock_irqsave(&trigger->leddev_list_lock, flags);
132                 list_add_tail(&led_cdev->trig_list, &trigger->led_cdevs);
133                 write_unlock_irqrestore(&trigger->leddev_list_lock, flags);
134                 if (trigger->activate)
135                         trigger->activate(led_cdev);
136         }
137         led_cdev->trigger = trigger;
138 }
139
140 void led_trigger_set_default(struct led_classdev *led_cdev)
141 {
142         struct led_trigger *trig;
143
144         if (!led_cdev->default_trigger)
145                 return;
146
147         read_lock(&triggers_list_lock);
148         write_lock(&led_cdev->trigger_lock);
149         list_for_each_entry(trig, &trigger_list, next_trig) {
150                 if (!strcmp(led_cdev->default_trigger, trig->name))
151                         led_trigger_set(led_cdev, trig);
152         }
153         write_unlock(&led_cdev->trigger_lock);
154         read_unlock(&triggers_list_lock);
155 }
156
157 int led_trigger_register(struct led_trigger *trigger)
158 {
159         struct led_classdev *led_cdev;
160
161         rwlock_init(&trigger->leddev_list_lock);
162         INIT_LIST_HEAD(&trigger->led_cdevs);
163
164         /* Add to the list of led triggers */
165         write_lock(&triggers_list_lock);
166         list_add_tail(&trigger->next_trig, &trigger_list);
167         write_unlock(&triggers_list_lock);
168
169         /* Register with any LEDs that have this as a default trigger */
170         read_lock(&leds_list_lock);
171         list_for_each_entry(led_cdev, &leds_list, node) {
172                 write_lock(&led_cdev->trigger_lock);
173                 if (!led_cdev->trigger && led_cdev->default_trigger &&
174                             !strcmp(led_cdev->default_trigger, trigger->name))
175                         led_trigger_set(led_cdev, trigger);
176                 write_unlock(&led_cdev->trigger_lock);
177         }
178         read_unlock(&leds_list_lock);
179
180         return 0;
181 }
182
183 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
184 {
185         struct led_trigger *trigger;
186
187         trigger = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
188
189         if (trigger) {
190                 trigger->name = name;
191                 led_trigger_register(trigger);
192         }
193         *tp = trigger;
194 }
195
196 void led_trigger_unregister(struct led_trigger *trigger)
197 {
198         struct led_classdev *led_cdev;
199
200         /* Remove from the list of led triggers */
201         write_lock(&triggers_list_lock);
202         list_del(&trigger->next_trig);
203         write_unlock(&triggers_list_lock);
204
205         /* Remove anyone actively using this trigger */
206         read_lock(&leds_list_lock);
207         list_for_each_entry(led_cdev, &leds_list, node) {
208                 write_lock(&led_cdev->trigger_lock);
209                 if (led_cdev->trigger == trigger)
210                         led_trigger_set(led_cdev, NULL);
211                 write_unlock(&led_cdev->trigger_lock);
212         }
213         read_unlock(&leds_list_lock);
214 }
215
216 void led_trigger_unregister_simple(struct led_trigger *trigger)
217 {
218         led_trigger_unregister(trigger);
219         kfree(trigger);
220 }
221
222 /* Used by LED Class */
223 EXPORT_SYMBOL_GPL(led_trigger_set);
224 EXPORT_SYMBOL_GPL(led_trigger_set_default);
225 EXPORT_SYMBOL_GPL(led_trigger_show);
226 EXPORT_SYMBOL_GPL(led_trigger_store);
227
228 /* LED Trigger Interface */
229 EXPORT_SYMBOL_GPL(led_trigger_register);
230 EXPORT_SYMBOL_GPL(led_trigger_unregister);
231
232 /* Simple LED Tigger Interface */
233 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
234 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
235 EXPORT_SYMBOL_GPL(led_trigger_event);
236
237 MODULE_AUTHOR("Richard Purdie");
238 MODULE_LICENSE("GPL");
239 MODULE_DESCRIPTION("LED Triggers Core");