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_async(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");
162