Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6
[linux-2.6.git] / drivers / leds / ledtrig-heartbeat.c
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/timer.h>
18 #include <linux/sched.h>
19 #include <linux/leds.h>
20 #include "leds.h"
21
22 struct heartbeat_trig_data {
23         unsigned int phase;
24         unsigned int period;
25         struct timer_list timer;
26 };
27
28 static void led_heartbeat_function(unsigned long data)
29 {
30         struct led_classdev *led_cdev = (struct led_classdev *) data;
31         struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
32         unsigned long brightness = LED_OFF;
33         unsigned long delay = 0;
34
35         /* acts like an actual heart beat -- ie thump-thump-pause... */
36         switch (heartbeat_data->phase) {
37         case 0:
38                 /*
39                  * The hyperbolic function below modifies the
40                  * heartbeat period length in dependency of the
41                  * current (1min) load. It goes through the points
42                  * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300.
43                  */
44                 heartbeat_data->period = 300 +
45                         (6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
46                 heartbeat_data->period =
47                         msecs_to_jiffies(heartbeat_data->period);
48                 delay = msecs_to_jiffies(70);
49                 heartbeat_data->phase++;
50                 brightness = led_cdev->max_brightness;
51                 break;
52         case 1:
53                 delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
54                 heartbeat_data->phase++;
55                 break;
56         case 2:
57                 delay = msecs_to_jiffies(70);
58                 heartbeat_data->phase++;
59                 brightness = led_cdev->max_brightness;
60                 break;
61         default:
62                 delay = heartbeat_data->period - heartbeat_data->period / 4 -
63                         msecs_to_jiffies(70);
64                 heartbeat_data->phase = 0;
65                 break;
66         }
67
68         led_set_brightness(led_cdev, brightness);
69         mod_timer(&heartbeat_data->timer, jiffies + delay);
70 }
71
72 static void heartbeat_trig_activate(struct led_classdev *led_cdev)
73 {
74         struct heartbeat_trig_data *heartbeat_data;
75
76         heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL);
77         if (!heartbeat_data)
78                 return;
79
80         led_cdev->trigger_data = heartbeat_data;
81         setup_timer(&heartbeat_data->timer,
82                     led_heartbeat_function, (unsigned long) led_cdev);
83         heartbeat_data->phase = 0;
84         led_heartbeat_function(heartbeat_data->timer.data);
85 }
86
87 static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
88 {
89         struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
90
91         if (heartbeat_data) {
92                 del_timer_sync(&heartbeat_data->timer);
93                 kfree(heartbeat_data);
94         }
95 }
96
97 static struct led_trigger heartbeat_led_trigger = {
98         .name     = "heartbeat",
99         .activate = heartbeat_trig_activate,
100         .deactivate = heartbeat_trig_deactivate,
101 };
102
103 static int __init heartbeat_trig_init(void)
104 {
105         return led_trigger_register(&heartbeat_led_trigger);
106 }
107
108 static void __exit heartbeat_trig_exit(void)
109 {
110         led_trigger_unregister(&heartbeat_led_trigger);
111 }
112
113 module_init(heartbeat_trig_init);
114 module_exit(heartbeat_trig_exit);
115
116 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
117 MODULE_DESCRIPTION("Heartbeat LED trigger");
118 MODULE_LICENSE("GPL");