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Message-Id: <1223374230-18413-2-git-send-email-giometti@enneenne.com>
Date: Tue, 7 Oct 2008 12:10:30 +0200
From: Rodolfo Giometti <giometti@...eenne.com>
To: linux-kernel@...r.kernel.org
Cc: Richard Purdie <rpurdie@...ys.net>,
Rodolfo Giometti <giometti@...ux.it>
Subject: [PATCH 1/1] led: add a backlight emulation trigger.
From: Rodolfo Giometti <giometti@...ux.it>
This allows LEDs to be controlled as a backlight device: they turn off
and on when the display is blanked and unblanked.
Signed-off-by: Rodolfo Giometti <giometti@...ux.it>
---
drivers/leds/Kconfig | 9 +++
drivers/leds/Makefile | 1 +
drivers/leds/ledtrig-backlight.c | 110 ++++++++++++++++++++++++++++++++++++++
3 files changed, 120 insertions(+), 0 deletions(-)
create mode 100644 drivers/leds/ledtrig-backlight.c
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 9556262..7f2294c 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -199,6 +199,15 @@ config LEDS_TRIGGER_HEARTBEAT
load average.
If unsure, say Y.
+config LEDS_TRIGGER_BACKLIGHT
+ tristate "LED backlight Trigger"
+ depends on LEDS_TRIGGERS
+ help
+ This allows LEDs to be controlled as a backlight device: they
+ turn off and on when the display is blanked and unblanked.
+
+ If unsure, say N.
+
config LEDS_TRIGGER_DEFAULT_ON
tristate "LED Default ON Trigger"
depends on LEDS_TRIGGERS
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index ff7982b..78d07ba 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -28,4 +28,5 @@ obj-$(CONFIG_LEDS_PCA955X) += leds-pca955x.o
obj-$(CONFIG_LEDS_TRIGGER_TIMER) += ledtrig-timer.o
obj-$(CONFIG_LEDS_TRIGGER_IDE_DISK) += ledtrig-ide-disk.o
obj-$(CONFIG_LEDS_TRIGGER_HEARTBEAT) += ledtrig-heartbeat.o
+obj-$(CONFIG_LEDS_TRIGGER_BACKLIGHT) += ledtrig-backlight.o
obj-$(CONFIG_LEDS_TRIGGER_DEFAULT_ON) += ledtrig-default-on.o
diff --git a/drivers/leds/ledtrig-backlight.c b/drivers/leds/ledtrig-backlight.c
new file mode 100644
index 0000000..d3dfcfb
--- /dev/null
+++ b/drivers/leds/ledtrig-backlight.c
@@ -0,0 +1,110 @@
+/*
+ * Backlight emulation LED trigger
+ *
+ * Copyright 2008 (C) Rodolfo Giometti <giometti@...ux.it>
+ * Copyright 2008 (C) Eurotech S.p.A. <info@...otech.it>
+ *
+ * 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 <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/fb.h>
+#include <linux/leds.h>
+#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 <giometti@...ux.it>");
+MODULE_DESCRIPTION("Backlight emulation LED trigger");
+MODULE_LICENSE("GPL v2");
--
1.5.4.3
--
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