From 132e9306beedd049bc5de037f1996731a2ca3eed Mon Sep 17 00:00:00 2001 From: Rodolfo Giometti Date: Mon, 13 Oct 2008 09:25:24 +0100 Subject: 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 Signed-off-by: Richard Purdie --- drivers/leds/ledtrig-backlight.c | 110 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 110 insertions(+) create mode 100644 drivers/leds/ledtrig-backlight.c (limited to 'drivers/leds/ledtrig-backlight.c') 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 @@ +/* + * Backlight emulation LED trigger + * + * Copyright 2008 (C) Rodolfo Giometti + * Copyright 2008 (C) Eurotech S.p.A. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#include +#include +#include +#include +#include +#include "leds.h" + +#define BLANK 1 +#define UNBLANK 0 + +struct bl_trig_notifier { + struct led_classdev *led; + int brightness; + int old_status; + struct notifier_block notifier; +}; + +static int fb_notifier_callback(struct notifier_block *p, + unsigned long event, void *data) +{ + struct bl_trig_notifier *n = container_of(p, + struct bl_trig_notifier, notifier); + struct led_classdev *led = n->led; + struct fb_event *fb_event = data; + int *blank = fb_event->data; + + switch (event) { + case FB_EVENT_BLANK : + if (*blank && n->old_status == UNBLANK) { + n->brightness = led->brightness; + led_set_brightness(led, LED_OFF); + n->old_status = BLANK; + } else if (!*blank && n->old_status == BLANK) { + led_set_brightness(led, n->brightness); + n->old_status = UNBLANK; + } + break; + } + + return 0; +} + +static void bl_trig_activate(struct led_classdev *led) +{ + int ret; + + struct bl_trig_notifier *n; + + n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL); + led->trigger_data = n; + if (!n) { + dev_err(led->dev, "unable to allocate backlight trigger\n"); + return; + } + + n->led = led; + n->brightness = led->brightness; + n->old_status = UNBLANK; + n->notifier.notifier_call = fb_notifier_callback; + + ret = fb_register_client(&n->notifier); + if (ret) + dev_err(led->dev, "unable to register backlight trigger\n"); +} + +static void bl_trig_deactivate(struct led_classdev *led) +{ + struct bl_trig_notifier *n = + (struct bl_trig_notifier *) led->trigger_data; + + if (n) { + fb_unregister_client(&n->notifier); + kfree(n); + } +} + +static struct led_trigger bl_led_trigger = { + .name = "backlight", + .activate = bl_trig_activate, + .deactivate = bl_trig_deactivate +}; + +static int __init bl_trig_init(void) +{ + return led_trigger_register(&bl_led_trigger); +} + +static void __exit bl_trig_exit(void) +{ + led_trigger_unregister(&bl_led_trigger); +} + +module_init(bl_trig_init); +module_exit(bl_trig_exit); + +MODULE_AUTHOR("Rodolfo Giometti "); +MODULE_DESCRIPTION("Backlight emulation LED trigger"); +MODULE_LICENSE("GPL v2"); -- cgit v1.2.3