[PATCH] LED: add LED heartbeat trigger

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>
Acked-by: Richard Purdie <rpurdie@rpsys.net>
Cc: "Nish Aravamudan" <nish.aravamudan@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 118 insertions, 0 deletions

diff --git a/drivers/leds/ledtrig-heartbeat.c b/drivers/leds/ledtrig-heartbeat.c
new file mode 100644
index 000000000000..4bf8cec8b8c1
--- /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 (1min) load. It goes through the points
+                 * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300.
+                 */
+                heartbeat_data->period = 300 +
+                        (6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
+                heartbeat_data->period =
+                        msecs_to_jiffies(heartbeat_data->period);
+                delay = msecs_to_jiffies(70);
+                heartbeat_data->phase++;
+                brightness = LED_FULL;
+                break;
+        case 1:
+                delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
+                heartbeat_data->phase++;
+                break;
+        case 2:
+                delay = msecs_to_jiffies(70);
+                heartbeat_data->phase++;
+                brightness = LED_FULL;
+                break;
+        default:
+                delay = heartbeat_data->period - heartbeat_data->period / 4 -
+                        msecs_to_jiffies(70);
+                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;
+        setup_timer(&heartbeat_data->timer,
+                    led_heartbeat_function, (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");