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 <linux/reboot.h>
 22#include "leds.h"
 23
 24static int panic_heartbeats;
 25
 26struct heartbeat_trig_data {
 27	unsigned int phase;
 28	unsigned int period;
 29	struct timer_list timer;
 30};
 31
 32static void led_heartbeat_function(unsigned long data)
 33{
 34	struct led_classdev *led_cdev = (struct led_classdev *) data;
 35	struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
 36	unsigned long brightness = LED_OFF;
 37	unsigned long delay = 0;
 38
 39	if (unlikely(panic_heartbeats)) {
 40		led_set_brightness(led_cdev, LED_OFF);
 41		return;
 42	}
 43
 44	/* acts like an actual heart beat -- ie thump-thump-pause... */
 45	switch (heartbeat_data->phase) {
 46	case 0:
 47		/*
 48		 * The hyperbolic function below modifies the
 49		 * heartbeat period length in dependency of the
 50		 * current (1min) load. It goes through the points
 51		 * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300.
 52		 */
 53		heartbeat_data->period = 300 +
 54			(6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
 55		heartbeat_data->period =
 56			msecs_to_jiffies(heartbeat_data->period);
 57		delay = msecs_to_jiffies(70);
 58		heartbeat_data->phase++;
 59		brightness = led_cdev->max_brightness;
 60		break;
 61	case 1:
 62		delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
 63		heartbeat_data->phase++;
 64		break;
 65	case 2:
 66		delay = msecs_to_jiffies(70);
 67		heartbeat_data->phase++;
 68		brightness = led_cdev->max_brightness;
 69		break;
 70	default:
 71		delay = heartbeat_data->period - heartbeat_data->period / 4 -
 72			msecs_to_jiffies(70);
 73		heartbeat_data->phase = 0;
 74		break;
 75	}
 76
 77	led_set_brightness(led_cdev, brightness);
 78	mod_timer(&heartbeat_data->timer, jiffies + delay);
 79}
 80
 81static void heartbeat_trig_activate(struct led_classdev *led_cdev)
 82{
 83	struct heartbeat_trig_data *heartbeat_data;
 84
 85	heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL);
 86	if (!heartbeat_data)
 87		return;
 88
 89	led_cdev->trigger_data = heartbeat_data;
 90	setup_timer(&heartbeat_data->timer,
 91		    led_heartbeat_function, (unsigned long) led_cdev);
 92	heartbeat_data->phase = 0;
 93	led_heartbeat_function(heartbeat_data->timer.data);
 94	led_cdev->activated = true;
 95}
 96
 97static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
 98{
 99	struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
100
101	if (led_cdev->activated) {
102		del_timer_sync(&heartbeat_data->timer);
103		kfree(heartbeat_data);
104		led_cdev->activated = false;
105	}
106}
107
108static struct led_trigger heartbeat_led_trigger = {
109	.name     = "heartbeat",
110	.activate = heartbeat_trig_activate,
111	.deactivate = heartbeat_trig_deactivate,
112};
113
114static int heartbeat_reboot_notifier(struct notifier_block *nb,
115				     unsigned long code, void *unused)
116{
117	led_trigger_unregister(&heartbeat_led_trigger);
118	return NOTIFY_DONE;
119}
120
121static int heartbeat_panic_notifier(struct notifier_block *nb,
122				     unsigned long code, void *unused)
123{
124	panic_heartbeats = 1;
125	return NOTIFY_DONE;
126}
127
128static struct notifier_block heartbeat_reboot_nb = {
129	.notifier_call = heartbeat_reboot_notifier,
130};
131
132static struct notifier_block heartbeat_panic_nb = {
133	.notifier_call = heartbeat_panic_notifier,
134};
135
136static int __init heartbeat_trig_init(void)
137{
138	int rc = led_trigger_register(&heartbeat_led_trigger);
139
140	if (!rc) {
141		atomic_notifier_chain_register(&panic_notifier_list,
142					       &heartbeat_panic_nb);
143		register_reboot_notifier(&heartbeat_reboot_nb);
144	}
145	return rc;
146}
147
148static void __exit heartbeat_trig_exit(void)
149{
150	unregister_reboot_notifier(&heartbeat_reboot_nb);
151	atomic_notifier_chain_unregister(&panic_notifier_list,
152					 &heartbeat_panic_nb);
153	led_trigger_unregister(&heartbeat_led_trigger);
154}
155
156module_init(heartbeat_trig_init);
157module_exit(heartbeat_trig_exit);
158
159MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
160MODULE_DESCRIPTION("Heartbeat LED trigger");
161MODULE_LICENSE("GPL");