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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>
Kim, Milof07fb522013-02-20 00:36:01 -080019#include "../leds.h"
Rodolfo Giometti132e9302008-10-13 09:25:24 +010020
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;
Janusz Krzysztofik9f9455a2011-01-12 16:59:20 -080029 unsigned invert;
Rodolfo Giometti132e9302008-10-13 09:25:24 +010030};
31
32static int fb_notifier_callback(struct notifier_block *p,
33 unsigned long event, void *data)
34{
35 struct bl_trig_notifier *n = container_of(p,
36 struct bl_trig_notifier, notifier);
37 struct led_classdev *led = n->led;
38 struct fb_event *fb_event = data;
Manfred Schlaeglc945cbc2013-08-13 04:17:05 -070039 int *blank;
40 int new_status;
Rodolfo Giometti132e9302008-10-13 09:25:24 +010041
Manfred Schlaeglc945cbc2013-08-13 04:17:05 -070042 /* If we aren't interested in this event, skip it immediately ... */
43 if (event != FB_EVENT_BLANK)
44 return 0;
Janusz Krzysztofik9f9455a2011-01-12 16:59:20 -080045
Manfred Schlaeglc945cbc2013-08-13 04:17:05 -070046 blank = fb_event->data;
47 new_status = *blank ? BLANK : UNBLANK;
Janusz Krzysztofik9f9455a2011-01-12 16:59:20 -080048
Manfred Schlaeglc945cbc2013-08-13 04:17:05 -070049 if (new_status == n->old_status)
50 return 0;
Janusz Krzysztofik9f9455a2011-01-12 16:59:20 -080051
Manfred Schlaeglc945cbc2013-08-13 04:17:05 -070052 if ((n->old_status == UNBLANK) ^ n->invert) {
53 n->brightness = led->brightness;
Jacek Anaszewski4d71a4a2014-11-14 02:50:18 -080054 led_set_brightness_async(led, LED_OFF);
Manfred Schlaeglc945cbc2013-08-13 04:17:05 -070055 } else {
Jacek Anaszewski4d71a4a2014-11-14 02:50:18 -080056 led_set_brightness_async(led, n->brightness);
Rodolfo Giometti132e9302008-10-13 09:25:24 +010057 }
58
Manfred Schlaeglc945cbc2013-08-13 04:17:05 -070059 n->old_status = new_status;
60
Rodolfo Giometti132e9302008-10-13 09:25:24 +010061 return 0;
62}
63
Janusz Krzysztofik9f9455a2011-01-12 16:59:20 -080064static ssize_t bl_trig_invert_show(struct device *dev,
65 struct device_attribute *attr, char *buf)
66{
67 struct led_classdev *led = dev_get_drvdata(dev);
68 struct bl_trig_notifier *n = led->trigger_data;
69
70 return sprintf(buf, "%u\n", n->invert);
71}
72
73static ssize_t bl_trig_invert_store(struct device *dev,
74 struct device_attribute *attr, const char *buf, size_t num)
75{
76 struct led_classdev *led = dev_get_drvdata(dev);
77 struct bl_trig_notifier *n = led->trigger_data;
78 unsigned long invert;
79 int ret;
80
Jingoo Han75253b32012-10-23 05:26:56 -070081 ret = kstrtoul(buf, 10, &invert);
Janusz Krzysztofik9f9455a2011-01-12 16:59:20 -080082 if (ret < 0)
83 return ret;
84
85 if (invert > 1)
86 return -EINVAL;
87
88 n->invert = invert;
89
90 /* After inverting, we need to update the LED. */
91 if ((n->old_status == BLANK) ^ n->invert)
Jacek Anaszewski4d71a4a2014-11-14 02:50:18 -080092 led_set_brightness_async(led, LED_OFF);
Janusz Krzysztofik9f9455a2011-01-12 16:59:20 -080093 else
Jacek Anaszewski4d71a4a2014-11-14 02:50:18 -080094 led_set_brightness_async(led, n->brightness);
Janusz Krzysztofik9f9455a2011-01-12 16:59:20 -080095
96 return num;
97}
98static DEVICE_ATTR(inverted, 0644, bl_trig_invert_show, bl_trig_invert_store);
99
Rodolfo Giometti132e9302008-10-13 09:25:24 +0100100static void bl_trig_activate(struct led_classdev *led)
101{
102 int ret;
103
104 struct bl_trig_notifier *n;
105
106 n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL);
107 led->trigger_data = n;
108 if (!n) {
109 dev_err(led->dev, "unable to allocate backlight trigger\n");
110 return;
111 }
112
Janusz Krzysztofik9f9455a2011-01-12 16:59:20 -0800113 ret = device_create_file(led->dev, &dev_attr_inverted);
114 if (ret)
115 goto err_invert;
116
Rodolfo Giometti132e9302008-10-13 09:25:24 +0100117 n->led = led;
118 n->brightness = led->brightness;
119 n->old_status = UNBLANK;
120 n->notifier.notifier_call = fb_notifier_callback;
121
122 ret = fb_register_client(&n->notifier);
123 if (ret)
124 dev_err(led->dev, "unable to register backlight trigger\n");
Shuah Khan03c091e2012-05-29 15:07:28 -0700125 led->activated = true;
Janusz Krzysztofik9f9455a2011-01-12 16:59:20 -0800126
127 return;
128
129err_invert:
130 led->trigger_data = NULL;
131 kfree(n);
Rodolfo Giometti132e9302008-10-13 09:25:24 +0100132}
133
134static void bl_trig_deactivate(struct led_classdev *led)
135{
136 struct bl_trig_notifier *n =
137 (struct bl_trig_notifier *) led->trigger_data;
138
Shuah Khan03c091e2012-05-29 15:07:28 -0700139 if (led->activated) {
Janusz Krzysztofik9f9455a2011-01-12 16:59:20 -0800140 device_remove_file(led->dev, &dev_attr_inverted);
Rodolfo Giometti132e9302008-10-13 09:25:24 +0100141 fb_unregister_client(&n->notifier);
142 kfree(n);
Shuah Khan03c091e2012-05-29 15:07:28 -0700143 led->activated = false;
Rodolfo Giometti132e9302008-10-13 09:25:24 +0100144 }
145}
146
147static struct led_trigger bl_led_trigger = {
148 .name = "backlight",
149 .activate = bl_trig_activate,
150 .deactivate = bl_trig_deactivate
151};
152
153static int __init bl_trig_init(void)
154{
155 return led_trigger_register(&bl_led_trigger);
156}
157
158static void __exit bl_trig_exit(void)
159{
160 led_trigger_unregister(&bl_led_trigger);
161}
162
163module_init(bl_trig_init);
164module_exit(bl_trig_exit);
165
166MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
167MODULE_DESCRIPTION("Backlight emulation LED trigger");
168MODULE_LICENSE("GPL v2");