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Subject[PATCH] LED: add LED heartbeat trigger
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Add an LED trigger acts like a heart beat.  This can be used as a
replacement of CONFIG_HEARTBEAT code exists in some arch's timer code.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 6265062..21bb7e8 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -87,5 +87,14 @@ config LEDS_TRIGGER_IDE_DISK
This allows LEDs to be controlled by IDE disk activity.
If unsure, say Y.

+config LEDS_TRIGGER_HEARTBEAT
+ tristate "LED Heartbeat Trigger"
+ depends LEDS_TRIGGERS
+ help
+ This allows LEDs to be controlled by a CPU load average.
+ The flash frequency is a hyperbolic function of the 5-minute
+ load average.
+ If unsure, say Y.
+
endmenu

diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 40f0426..1dc79b5 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -15,3 +15,4 @@ obj-$(CONFIG_LEDS_S3C24XX) += leds-s3c2
# LED Triggers
obj-$(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
diff --git a/drivers/leds/ledtrig-heartbeat.c b/drivers/leds/ledtrig-heartbeat.c
new file mode 100644
index 0000000..07ac645
--- /dev/null
+++ b/drivers/leds/ledtrig-heartbeat.c
@@ -0,0 +1,118 @@
+/*
+ * LED Heartbeat Trigger
+ *
+ * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
+ *
+ * Based on Richard Purdie's ledtrig-timer.c and some arch's
+ * CONFIG_HEARTBEAT code.
+ *
+ * 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/timer.h>
+#include <linux/sched.h>
+#include <linux/leds.h>
+#include "leds.h"
+
+struct heartbeat_trig_data {
+ unsigned int phase;
+ unsigned int period;
+ struct timer_list timer;
+};
+
+static void led_heartbeat_function(unsigned long data)
+{
+ struct led_classdev *led_cdev = (struct led_classdev *) data;
+ struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
+ unsigned long brightness = LED_OFF;
+ unsigned long delay = 0;
+
+ /* acts like an actual heart beat -- ie thump-thump-pause... */
+ switch (heartbeat_data->phase) {
+ case 0:
+ /*
+ * The hyperbolic function below modifies the
+ * heartbeat period length in dependency of the
+ * current (5min) load. It goes through the points
+ * f(0)=126, f(1)=86, f(5)=51, f(inf)->30.
+ */
+ heartbeat_data->period = 30 +
+ (672 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
+ heartbeat_data->period = heartbeat_data->period * HZ / 100;
+ delay = 7 * HZ / 100;
+ heartbeat_data->phase++;
+ brightness = LED_FULL;
+ break;
+ case 1:
+ delay = heartbeat_data->period / 4 - 7 * HZ / 100;
+ heartbeat_data->phase++;
+ break;
+ case 2:
+ delay = 7 * HZ / 100;
+ heartbeat_data->phase++;
+ brightness = LED_FULL;
+ break;
+ default:
+ delay = heartbeat_data->period - heartbeat_data->period / 4 -
+ 7 * HZ / 100;
+ heartbeat_data->phase = 0;
+ break;
+ }
+
+ led_set_brightness(led_cdev, brightness);
+ mod_timer(&heartbeat_data->timer, jiffies + delay);
+}
+
+static void heartbeat_trig_activate(struct led_classdev *led_cdev)
+{
+ struct heartbeat_trig_data *heartbeat_data;
+
+ heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL);
+ if (!heartbeat_data)
+ return;
+
+ led_cdev->trigger_data = heartbeat_data;
+ init_timer(&heartbeat_data->timer);
+ heartbeat_data->timer.function = led_heartbeat_function;
+ heartbeat_data->timer.data = (unsigned long) led_cdev;
+ heartbeat_data->phase = 0;
+ led_heartbeat_function(heartbeat_data->timer.data);
+}
+
+static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
+{
+ struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
+
+ if (heartbeat_data) {
+ del_timer_sync(&heartbeat_data->timer);
+ kfree(heartbeat_data);
+ }
+}
+
+static struct led_trigger heartbeat_led_trigger = {
+ .name = "heartbeat",
+ .activate = heartbeat_trig_activate,
+ .deactivate = heartbeat_trig_deactivate,
+};
+
+static int __init heartbeat_trig_init(void)
+{
+ return led_trigger_register(&heartbeat_led_trigger);
+}
+
+static void __exit heartbeat_trig_exit(void)
+{
+ led_trigger_unregister(&heartbeat_led_trigger);
+}
+
+module_init(heartbeat_trig_init);
+module_exit(heartbeat_trig_exit);
+
+MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
+MODULE_DESCRIPTION("Heartbeat LED trigger");
+MODULE_LICENSE("GPL");
-
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