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");