1/*
  2 * LED Heartbeat Trigger
  3 *
  4 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
  5 *
  6 * Based on Richard Purdie's ledtrig-timer.c and some arch's
  7 * CONFIG_HEARTBEAT code.
  8 *
  9 * This program is free software; you can redistribute it and/or modify
 10 * it under the terms of the GNU General Public License version 2 as
 11 * published by the Free Software Foundation.
 12 *
 13 */
 14#include <linux/module.h>
 15#include <linux/kernel.h>
 16#include <linux/init.h>
 17#include <linux/slab.h>
 18#include <linux/timer.h>
 19#include <linux/sched.h>
 20#include <linux/leds.h>
 21#include "leds.h"
 22
 23struct heartbeat_trig_data {
 24	unsigned int phase;
 25	unsigned int period;
 26	struct timer_list timer;
 27};
 28
 29static void led_heartbeat_function(unsigned long data)
 30{
 31	struct led_classdev *led_cdev = (struct led_classdev *) data;
 32	struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
 33	unsigned long brightness = LED_OFF;
 34	unsigned long delay = 0;
 35
 36	/* acts like an actual heart beat -- ie thump-thump-pause... */
 37	switch (heartbeat_data->phase) {
 38	case 0:
 39		/*
 40		 * The hyperbolic function below modifies the
 41		 * heartbeat period length in dependency of the
 42		 * current (1min) load. It goes through the points
 43		 * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300.
 44		 */
 45		heartbeat_data->period = 300 +
 46			(6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
 47		heartbeat_data->period =
 48			msecs_to_jiffies(heartbeat_data->period);
 49		delay = msecs_to_jiffies(70);
 50		heartbeat_data->phase++;
 51		brightness = led_cdev->max_brightness;
 52		break;
 53	case 1:
 54		delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
 55		heartbeat_data->phase++;
 56		break;
 57	case 2:
 58		delay = msecs_to_jiffies(70);
 59		heartbeat_data->phase++;
 60		brightness = led_cdev->max_brightness;
 61		break;
 62	default:
 63		delay = heartbeat_data->period - heartbeat_data->period / 4 -
 64			msecs_to_jiffies(70);
 65		heartbeat_data->phase = 0;
 66		break;
 67	}
 68
 69	led_set_brightness(led_cdev, brightness);
 70	mod_timer(&heartbeat_data->timer, jiffies + delay);
 71}
 72
 73static void heartbeat_trig_activate(struct led_classdev *led_cdev)
 74{
 75	struct heartbeat_trig_data *heartbeat_data;
 76
 77	heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL);
 78	if (!heartbeat_data)
 79		return;
 80
 81	led_cdev->trigger_data = heartbeat_data;
 82	setup_timer(&heartbeat_data->timer,
 83		    led_heartbeat_function, (unsigned long) led_cdev);
 84	heartbeat_data->phase = 0;
 85	led_heartbeat_function(heartbeat_data->timer.data);
 86}
 87
 88static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
 89{
 90	struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
 91
 92	if (heartbeat_data) {
 93		del_timer_sync(&heartbeat_data->timer);
 94		kfree(heartbeat_data);
 95	}
 96}
 97
 98static struct led_trigger heartbeat_led_trigger = {
 99	.name     = "heartbeat",
100	.activate = heartbeat_trig_activate,
101	.deactivate = heartbeat_trig_deactivate,
102};
103
104static int __init heartbeat_trig_init(void)
105{
106	return led_trigger_register(&heartbeat_led_trigger);
107}
108
109static void __exit heartbeat_trig_exit(void)
110{
111	led_trigger_unregister(&heartbeat_led_trigger);
112}
113
114module_init(heartbeat_trig_init);
115module_exit(heartbeat_trig_exit);
116
117MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
118MODULE_DESCRIPTION("Heartbeat LED trigger");
119MODULE_LICENSE("GPL");