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authorRodolfo Giometti <giometti@linux.it>2008-10-13 04:25:24 -0400
committerRichard Purdie <rpurdie@rpsys.net>2008-10-20 17:34:12 -0400
commit132e9306beedd049bc5de037f1996731a2ca3eed (patch)
tree74284b6fb45299ccbfa754e9297a33ad0f8ff322 /drivers/leds/ledtrig-backlight.c
parent9e84561c8c8671d9e58d1893cc524a71b20c9183 (diff)
leds: Add backlight LED trigger
This allows LEDs to be controlled as a backlight device where they turn off and on when the display is blanked and unblanked. This is useful where you need various key backlight LEDs to dim at the same time as the backlight. Signed-off-by: Rodolfo Giometti <giometti@linux.it> Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
Diffstat (limited to 'drivers/leds/ledtrig-backlight.c')
-rw-r--r--drivers/leds/ledtrig-backlight.c110
1 files changed, 110 insertions, 0 deletions
diff --git a/drivers/leds/ledtrig-backlight.c b/drivers/leds/ledtrig-backlight.c
new file mode 100644
index 000000000000..d3dfcfb417b8
--- /dev/null
+++ b/drivers/leds/ledtrig-backlight.c
@@ -0,0 +1,110 @@
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");