"default-on" LED Trigger

The current LED subsystem always initialises LEDs in the OFF state. This is fine for most LEDs but some should be on right from boot (e.g. POWER LED). Following some discussion with the LED subsystem maintainers, a trigger was recommended as the best way to implement this functionality.

Here is a patch to add a new trigger "default-on" which will initialise an LED in the ON state. It is not compiled by default.

Particular thanks to Rod Whitby for all his help with this.

Signed-off-by: Nick Forbes <nick.forbes@incepta.com>

SVN-Revision: 10348

target/linux/generic-2.6/config-2.6.23

@@ -677,6 +677,7 @@ CONFIG_LEDS_TRIGGER_HEARTBEAT=y
 # CONFIG_LEDS_TRIGGER_IDE_DISK is not set
 # CONFIG_LEDS_TRIGGER_MORSE is not set
 CONFIG_LEDS_TRIGGER_TIMER=y
+# CONFIG_LEDS_TRIGGER_DEFAULT_ON is not set
 # CONFIG_LEGACY_PTYS is not set
 CONFIG_LIBCRC32C=m
 # CONFIG_LIBERTAS is not set

target/linux/generic-2.6/files/drivers/leds/ledtrig-default-on.c

@@ -0,0 +1,45 @@
+/*
+ * LED Kernel Default ON Trigger
+ *
+ * Copyright 2008 Nick Forbes <nick.forbes@incepta.com>
+ *
+ * Based on Richard Purdie's ledtrig-timer.c.
+ *
+ * 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/leds.h>
+#include "leds.h"
+
+static void defon_trig_activate(struct led_classdev *led_cdev)
+{
+	led_set_brightness(led_cdev, LED_FULL);
+}
+
+static struct led_trigger defon_led_trigger = {
+	.name     = "default-on",
+	.activate = defon_trig_activate,
+};
+
+static int __init defon_trig_init(void)
+{
+	return led_trigger_register(&defon_led_trigger);
+}
+
+static void __exit defon_trig_exit(void)
+{
+	led_trigger_unregister(&defon_led_trigger);
+}
+
+module_init(defon_trig_init);
+module_exit(defon_trig_exit);
+
+MODULE_AUTHOR("Nick Forbes <nick.forbes@incepta.com>");
+MODULE_DESCRIPTION("Default-ON LED trigger");
+MODULE_LICENSE("GPL");

target/linux/generic-2.6/patches-2.6.23/402-ledtrig_default_on.patch

@@ -0,0 +1,23 @@
+diff -ur linux-2.6.23.1.orig/drivers/leds/Kconfig linux-2.6.23.1/drivers/leds/Kconfig
+--- linux-2.6.23.1.orig/drivers/leds/Kconfig	2007-12-01 00:41:03.000000000 +1300
++++ linux-2.6.23.1/drivers/leds/Kconfig	2007-12-01 01:26:43.000000000 +1300
+@@ -137,4 +137,11 @@
+ 	tristate "LED Morse Trigger"
+ 	depends on LEDS_TRIGGERS
+ 
++config LEDS_TRIGGER_DEFAULT_ON
++	tristate "LED Default ON Trigger"
++	depends on LEDS_TRIGGERS
++	help
++	  This allows LEDs to be initialised in the ON state.
++	  If unsure, say Y.
++
+ endif # NEW_LEDS
+diff -ur linux-2.6.23.1.orig/drivers/leds/Makefile linux-2.6.23.1/drivers/leds/Makefile
+--- linux-2.6.23.1.orig/drivers/leds/Makefile	2007-12-01 00:41:03.000000000 +1300
++++ linux-2.6.23.1/drivers/leds/Makefile	2007-12-01 01:27:12.000000000 +1300
+@@ -23,3 +23,4 @@
+ obj-$(CONFIG_LEDS_TRIGGER_IDE_DISK)	+= ledtrig-ide-disk.o
+ obj-$(CONFIG_LEDS_TRIGGER_HEARTBEAT)	+= ledtrig-heartbeat.o
+ obj-$(CONFIG_LEDS_TRIGGER_MORSE)	+= ledtrig-morse.o
++obj-$(CONFIG_LEDS_TRIGGER_DEFAULT_ON)	+= ledtrig-default-on.o