2 * Backlight emulation LED trigger
4 * Copyright 2008 (C) Rodolfo Giometti <giometti@linux.it>
5 * Copyright 2008 (C) Eurotech S.p.A. <info@eurotech.it>
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.
13 #include <linux/module.h>
14 #include <linux/kernel.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
18 #include <linux/leds.h>
24 struct bl_trig_notifier {
25 struct led_classdev *led;
28 struct notifier_block notifier;
32 static int fb_notifier_callback(struct notifier_block *p,
33 unsigned long event, void *data)
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;
39 int *blank = fb_event->data;
40 int new_status = *blank ? BLANK : UNBLANK;
44 if (new_status == n->old_status)
47 if ((n->old_status == UNBLANK) ^ n->invert) {
48 n->brightness = led->brightness;
49 led_set_brightness(led, LED_OFF);
51 led_set_brightness(led, n->brightness);
54 n->old_status = new_status;
62 static ssize_t bl_trig_invert_show(struct device *dev,
63 struct device_attribute *attr, char *buf)
65 struct led_classdev *led = dev_get_drvdata(dev);
66 struct bl_trig_notifier *n = led->trigger_data;
68 return sprintf(buf, "%u\n", n->invert);
71 static ssize_t bl_trig_invert_store(struct device *dev,
72 struct device_attribute *attr, const char *buf, size_t num)
74 struct led_classdev *led = dev_get_drvdata(dev);
75 struct bl_trig_notifier *n = led->trigger_data;
79 ret = strict_strtoul(buf, 10, &invert);
88 /* After inverting, we need to update the LED. */
89 if ((n->old_status == BLANK) ^ n->invert)
90 led_set_brightness(led, LED_OFF);
92 led_set_brightness(led, n->brightness);
96 static DEVICE_ATTR(inverted, 0644, bl_trig_invert_show, bl_trig_invert_store);
98 static void bl_trig_activate(struct led_classdev *led)
102 struct bl_trig_notifier *n;
104 n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL);
105 led->trigger_data = n;
107 dev_err(led->dev, "unable to allocate backlight trigger\n");
111 ret = device_create_file(led->dev, &dev_attr_inverted);
116 n->brightness = led->brightness;
117 n->old_status = UNBLANK;
118 n->notifier.notifier_call = fb_notifier_callback;
120 ret = fb_register_client(&n->notifier);
122 dev_err(led->dev, "unable to register backlight trigger\n");
127 led->trigger_data = NULL;
131 static void bl_trig_deactivate(struct led_classdev *led)
133 struct bl_trig_notifier *n =
134 (struct bl_trig_notifier *) led->trigger_data;
137 device_remove_file(led->dev, &dev_attr_inverted);
138 fb_unregister_client(&n->notifier);
143 static struct led_trigger bl_led_trigger = {
145 .activate = bl_trig_activate,
146 .deactivate = bl_trig_deactivate
149 static int __init bl_trig_init(void)
151 return led_trigger_register(&bl_led_trigger);
154 static void __exit bl_trig_exit(void)
156 led_trigger_unregister(&bl_led_trigger);
159 module_init(bl_trig_init);
160 module_exit(bl_trig_exit);
162 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
163 MODULE_DESCRIPTION("Backlight emulation LED trigger");
164 MODULE_LICENSE("GPL v2");