tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
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>
15#include <linux/init.h>
16#include <linux/fb.h>
17#include <linux/leds.h>
18#include "leds.h"
19
20#define BLANK 1
21#define UNBLANK 0
22
23struct bl_trig_notifier {
24 struct led_classdev *led;
25 int brightness;
26 int old_status;
27 struct notifier_block notifier;
28};
29
30static int fb_notifier_callback(struct notifier_block *p,
31 unsigned long event, void *data)
32{
33 struct bl_trig_notifier *n = container_of(p,
34 struct bl_trig_notifier, notifier);
35 struct led_classdev *led = n->led;
36 struct fb_event *fb_event = data;
37 int *blank = fb_event->data;
38
39 switch (event) {
40 case FB_EVENT_BLANK :
41 if (*blank && n->old_status == UNBLANK) {
42 n->brightness = led->brightness;
43 led_set_brightness(led, LED_OFF);
44 n->old_status = BLANK;
45 } else if (!*blank && n->old_status == BLANK) {
46 led_set_brightness(led, n->brightness);
47 n->old_status = UNBLANK;
48 }
49 break;
50 }
51
52 return 0;
53}
54
55static void bl_trig_activate(struct led_classdev *led)
56{
57 int ret;
58
59 struct bl_trig_notifier *n;
60
61 n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL);
62 led->trigger_data = n;
63 if (!n) {
64 dev_err(led->dev, "unable to allocate backlight trigger\n");
65 return;
66 }
67
68 n->led = led;
69 n->brightness = led->brightness;
70 n->old_status = UNBLANK;
71 n->notifier.notifier_call = fb_notifier_callback;
72
73 ret = fb_register_client(&n->notifier);
74 if (ret)
75 dev_err(led->dev, "unable to register backlight trigger\n");
76}
77
78static void bl_trig_deactivate(struct led_classdev *led)
79{
80 struct bl_trig_notifier *n =
81 (struct bl_trig_notifier *) led->trigger_data;
82
83 if (n) {
84 fb_unregister_client(&n->notifier);
85 kfree(n);
86 }
87}
88
89static struct led_trigger bl_led_trigger = {
90 .name = "backlight",
91 .activate = bl_trig_activate,
92 .deactivate = bl_trig_deactivate
93};
94
95static int __init bl_trig_init(void)
96{
97 return led_trigger_register(&bl_led_trigger);
98}
99
100static void __exit bl_trig_exit(void)
101{
102 led_trigger_unregister(&bl_led_trigger);
103}
104
105module_init(bl_trig_init);
106module_exit(bl_trig_exit);
107
108MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
109MODULE_DESCRIPTION("Backlight emulation LED trigger");
110MODULE_LICENSE("GPL v2");