LXR linux/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
  22struct heartbeat_trig_data {
  23        unsigned int phase;
  24        unsigned int period;
  25        struct timer_list timer;
  26};
  27
  28static 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
  72static 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
  87static 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
  97static struct led_trigger heartbeat_led_trigger = {
  98        .name     = "heartbeat",
  99        .activate = heartbeat_trig_activate,
 100        .deactivate = heartbeat_trig_deactivate,
 101};
 102
 103static int __init heartbeat_trig_init(void)
 104{
 105        return led_trigger_register(&heartbeat_led_trigger);
 106}
 107
 108static void __exit heartbeat_trig_exit(void)
 109{
 110        led_trigger_unregister(&heartbeat_led_trigger);
 111}
 112
 113module_init(heartbeat_trig_init);
 114module_exit(heartbeat_trig_exit);
 115
 116MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 117MODULE_DESCRIPTION("Heartbeat LED trigger");
 118MODULE_LICENSE("GPL");
 119