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
24 static int panic_heartbeats;
25
26 struct heartbeat_trig_data {
27 unsigned int phase;
28 unsigned int period;
29 struct timer_list timer;
30 };
31
led_heartbeat_function(unsigned long data)32 static 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
heartbeat_trig_activate(struct led_classdev * led_cdev)81 static 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
heartbeat_trig_deactivate(struct led_classdev * led_cdev)97 static 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
108 static struct led_trigger heartbeat_led_trigger = {
109 .name = "heartbeat",
110 .activate = heartbeat_trig_activate,
111 .deactivate = heartbeat_trig_deactivate,
112 };
113
heartbeat_reboot_notifier(struct notifier_block * nb,unsigned long code,void * unused)114 static 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
heartbeat_panic_notifier(struct notifier_block * nb,unsigned long code,void * unused)121 static 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
128 static struct notifier_block heartbeat_reboot_nb = {
129 .notifier_call = heartbeat_reboot_notifier,
130 };
131
132 static struct notifier_block heartbeat_panic_nb = {
133 .notifier_call = heartbeat_panic_notifier,
134 };
135
heartbeat_trig_init(void)136 static 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
heartbeat_trig_exit(void)148 static 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
156 module_init(heartbeat_trig_init);
157 module_exit(heartbeat_trig_exit);
158
159 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
160 MODULE_DESCRIPTION("Heartbeat LED trigger");
161 MODULE_LICENSE("GPL");
162