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132e9306 RG |
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> | |
5a0e3ad6 | 15 | #include <linux/slab.h> |
132e9306 RG |
16 | #include <linux/init.h> |
17 | #include <linux/fb.h> | |
18 | #include <linux/leds.h> | |
f07fb521 | 19 | #include "../leds.h" |
132e9306 RG |
20 | |
21 | #define BLANK 1 | |
22 | #define UNBLANK 0 | |
23 | ||
24 | struct bl_trig_notifier { | |
25 | struct led_classdev *led; | |
26 | int brightness; | |
27 | int old_status; | |
28 | struct notifier_block notifier; | |
9f9455ae | 29 | unsigned invert; |
132e9306 RG |
30 | }; |
31 | ||
32 | static 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; | |
c945cbcf MS |
39 | int *blank; |
40 | int new_status; | |
132e9306 | 41 | |
c945cbcf MS |
42 | /* If we aren't interested in this event, skip it immediately ... */ |
43 | if (event != FB_EVENT_BLANK) | |
44 | return 0; | |
9f9455ae | 45 | |
c945cbcf MS |
46 | blank = fb_event->data; |
47 | new_status = *blank ? BLANK : UNBLANK; | |
9f9455ae | 48 | |
c945cbcf MS |
49 | if (new_status == n->old_status) |
50 | return 0; | |
9f9455ae | 51 | |
c945cbcf MS |
52 | if ((n->old_status == UNBLANK) ^ n->invert) { |
53 | n->brightness = led->brightness; | |
81fe8e5b | 54 | led_set_brightness_nosleep(led, LED_OFF); |
c945cbcf | 55 | } else { |
81fe8e5b | 56 | led_set_brightness_nosleep(led, n->brightness); |
132e9306 RG |
57 | } |
58 | ||
c945cbcf MS |
59 | n->old_status = new_status; |
60 | ||
132e9306 RG |
61 | return 0; |
62 | } | |
63 | ||
9f9455ae JK |
64 | static 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 | ||
73 | static 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 | ||
75253b3c | 81 | ret = kstrtoul(buf, 10, &invert); |
9f9455ae JK |
82 | 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) | |
81fe8e5b | 92 | led_set_brightness_nosleep(led, LED_OFF); |
9f9455ae | 93 | else |
81fe8e5b | 94 | led_set_brightness_nosleep(led, n->brightness); |
9f9455ae JK |
95 | |
96 | return num; | |
97 | } | |
98 | static DEVICE_ATTR(inverted, 0644, bl_trig_invert_show, bl_trig_invert_store); | |
99 | ||
132e9306 RG |
100 | static 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 | ||
9f9455ae JK |
113 | ret = device_create_file(led->dev, &dev_attr_inverted); |
114 | if (ret) | |
115 | goto err_invert; | |
116 | ||
132e9306 RG |
117 | 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"); | |
03c091e5 | 125 | led->activated = true; |
9f9455ae JK |
126 | |
127 | return; | |
128 | ||
129 | err_invert: | |
130 | led->trigger_data = NULL; | |
131 | kfree(n); | |
132e9306 RG |
132 | } |
133 | ||
134 | static void bl_trig_deactivate(struct led_classdev *led) | |
135 | { | |
136 | struct bl_trig_notifier *n = | |
137 | (struct bl_trig_notifier *) led->trigger_data; | |
138 | ||
03c091e5 | 139 | if (led->activated) { |
9f9455ae | 140 | device_remove_file(led->dev, &dev_attr_inverted); |
132e9306 RG |
141 | fb_unregister_client(&n->notifier); |
142 | kfree(n); | |
03c091e5 | 143 | led->activated = false; |
132e9306 RG |
144 | } |
145 | } | |
146 | ||
147 | static struct led_trigger bl_led_trigger = { | |
148 | .name = "backlight", | |
149 | .activate = bl_trig_activate, | |
150 | .deactivate = bl_trig_deactivate | |
151 | }; | |
152 | ||
153 | static int __init bl_trig_init(void) | |
154 | { | |
155 | return led_trigger_register(&bl_led_trigger); | |
156 | } | |
157 | ||
158 | static void __exit bl_trig_exit(void) | |
159 | { | |
160 | led_trigger_unregister(&bl_led_trigger); | |
161 | } | |
162 | ||
163 | module_init(bl_trig_init); | |
164 | module_exit(bl_trig_exit); | |
165 | ||
166 | MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); | |
167 | MODULE_DESCRIPTION("Backlight emulation LED trigger"); | |
168 | MODULE_LICENSE("GPL v2"); |