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 <linux/reboot.h>
  22 #include "leds.h"
  23
  24 struct heartbeat_trig_data {
  25         unsigned int phase;
  26         unsigned int period;
  27         struct timer_list timer;
  28 };
  29
  30 static void led_heartbeat_function(unsigned long data)
  31 {
  32         struct led_classdev *led_cdev = (struct led_classdev *) data;
  33         struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
  34         unsigned long brightness = LED_OFF;
  35         unsigned long delay = 0;
  36
  37         /* acts like an actual heart beat -- ie thump-thump-pause... */
  38         switch (heartbeat_data->phase) {
  39         case 0:
  40                 /*
  41                  * The hyperbolic function below modifies the
  42                  * heartbeat period length in dependency of the
  43                  * current (1min) load. It goes through the points
  44                  * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300.
  45                  */
  46                 heartbeat_data->period = 300 +
  47                         (6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
  48                 heartbeat_data->period =
  49                         msecs_to_jiffies(heartbeat_data->period);
  50                 delay = msecs_to_jiffies(70);
  51                 heartbeat_data->phase++;
  52                 brightness = led_cdev->max_brightness;
  53                 break;
  54         case 1:
  55                 delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
  56                 heartbeat_data->phase++;
  57                 break;
  58         case 2:
  59                 delay = msecs_to_jiffies(70);
  60                 heartbeat_data->phase++;
  61                 brightness = led_cdev->max_brightness;
  62                 break;
  63         default:
  64                 delay = heartbeat_data->period - heartbeat_data->period / 4 -
  65                         msecs_to_jiffies(70);
  66                 heartbeat_data->phase = 0;
  67                 break;
  68         }
  69
  70         led_set_brightness(led_cdev, brightness);
  71         mod_timer(&heartbeat_data->timer, jiffies + delay);
  72 }
  73
  74 static void heartbeat_trig_activate(struct led_classdev *led_cdev)
  75 {
  76         struct heartbeat_trig_data *heartbeat_data;
  77
  78         heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL);
  79         if (!heartbeat_data)
  80                 return;
  81
  82         led_cdev->trigger_data = heartbeat_data;
  83         setup_timer(&heartbeat_data->timer,
  84                     led_heartbeat_function, (unsigned long) led_cdev);
  85         heartbeat_data->phase = 0;
  86         led_heartbeat_function(heartbeat_data->timer.data);
  87         led_cdev->activated = true;
  88 }
  89
  90 static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
  91 {
  92         struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
  93
  94         if (led_cdev->activated) {
  95                 del_timer_sync(&heartbeat_data->timer);
  96                 kfree(heartbeat_data);
  97                 led_cdev->activated = false;
  98         }
  99 }
 100
 101 static struct led_trigger heartbeat_led_trigger = {
 102         .name     = "heartbeat",
 103         .activate = heartbeat_trig_activate,
 104         .deactivate = heartbeat_trig_deactivate,
 105 };
 106
 107 static int heartbeat_reboot_notifier(struct notifier_block *nb,
 108                                      unsigned long code, void *unused)
 109 {
 110         led_trigger_unregister(&heartbeat_led_trigger);
 111         return NOTIFY_DONE;
 112 }
 113
 114 static struct notifier_block heartbeat_reboot_nb = {
 115         .notifier_call = heartbeat_reboot_notifier,
 116 };
 117
 118 static struct notifier_block heartbeat_panic_nb = {
 119         .notifier_call = heartbeat_reboot_notifier,
 120 };
 121
 122 static int __init heartbeat_trig_init(void)
 123 {
 124         int rc = led_trigger_register(&heartbeat_led_trigger);
 125
 126         if (!rc) {
 127                 atomic_notifier_chain_register(&panic_notifier_list,
 128                                                &heartbeat_panic_nb);
 129                 register_reboot_notifier(&heartbeat_reboot_nb);
 130         }
 131         return rc;
 132 }
 133
 134 static void __exit heartbeat_trig_exit(void)
 135 {
 136         unregister_reboot_notifier(&heartbeat_reboot_nb);
 137         atomic_notifier_chain_unregister(&panic_notifier_list,
 138                                          &heartbeat_panic_nb);
 139         led_trigger_unregister(&heartbeat_led_trigger);
 140 }
 141
 142 module_init(heartbeat_trig_init);
 143 module_exit(heartbeat_trig_exit);
 144
 145 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 146 MODULE_DESCRIPTION("Heartbeat LED trigger");
 147 MODULE_LICENSE("GPL");