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