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Rodolfo Giometti132e9302008-10-13 09:25:24 +01001/*
2 * Backlight emulation LED trigger
3 *
4 * Copyright 2008 (C) Rodolfo Giometti <giometti@linux.it>
5 * Copyright 2008 (C) Eurotech S.p.A. <info@eurotech.it>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 */
12
13#include <linux/module.h>
14#include <linux/kernel.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090015#include <linux/slab.h>
Rodolfo Giometti132e9302008-10-13 09:25:24 +010016#include <linux/init.h>
17#include <linux/fb.h>
18#include <linux/leds.h>
19#include "leds.h"
20
21#define BLANK 1
22#define UNBLANK 0
23
24struct bl_trig_notifier {
25 struct led_classdev *led;
26 int brightness;
27 int old_status;
28 struct notifier_block notifier;
29};
30
31static int fb_notifier_callback(struct notifier_block *p,
32 unsigned long event, void *data)
33{
34 struct bl_trig_notifier *n = container_of(p,
35 struct bl_trig_notifier, notifier);
36 struct led_classdev *led = n->led;
37 struct fb_event *fb_event = data;
38 int *blank = fb_event->data;
39
40 switch (event) {
41 case FB_EVENT_BLANK :
42 if (*blank && n->old_status == UNBLANK) {
43 n->brightness = led->brightness;
44 led_set_brightness(led, LED_OFF);
45 n->old_status = BLANK;
46 } else if (!*blank && n->old_status == BLANK) {
47 led_set_brightness(led, n->brightness);
48 n->old_status = UNBLANK;
49 }
50 break;
51 }
52
53 return 0;
54}
55
56static void bl_trig_activate(struct led_classdev *led)
57{
58 int ret;
59
60 struct bl_trig_notifier *n;
61
62 n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL);
63 led->trigger_data = n;
64 if (!n) {
65 dev_err(led->dev, "unable to allocate backlight trigger\n");
66 return;
67 }
68
69 n->led = led;
70 n->brightness = led->brightness;
71 n->old_status = UNBLANK;
72 n->notifier.notifier_call = fb_notifier_callback;
73
74 ret = fb_register_client(&n->notifier);
75 if (ret)
76 dev_err(led->dev, "unable to register backlight trigger\n");
77}
78
79static void bl_trig_deactivate(struct led_classdev *led)
80{
81 struct bl_trig_notifier *n =
82 (struct bl_trig_notifier *) led->trigger_data;
83
84 if (n) {
85 fb_unregister_client(&n->notifier);
86 kfree(n);
87 }
88}
89
90static struct led_trigger bl_led_trigger = {
91 .name = "backlight",
92 .activate = bl_trig_activate,
93 .deactivate = bl_trig_deactivate
94};
95
96static int __init bl_trig_init(void)
97{
98 return led_trigger_register(&bl_led_trigger);
99}
100
101static void __exit bl_trig_exit(void)
102{
103 led_trigger_unregister(&bl_led_trigger);
104}
105
106module_init(bl_trig_init);
107module_exit(bl_trig_exit);
108
109MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
110MODULE_DESCRIPTION("Backlight emulation LED trigger");
111MODULE_LICENSE("GPL v2");