linux/drivers/leds/ledtrig-heartbeat.c
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   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
  24static int panic_heartbeats;
  25
  26struct heartbeat_trig_data {
  27        unsigned int phase;
  28        unsigned int period;
  29        struct timer_list timer;
  30};
  31
  32static void led_heartbeat_function(unsigned long data)
  33{
  34        struct led_classdev *led_cdev = (struct led_classdev *) data;
  35        struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
  36        unsigned long brightness = LED_OFF;
  37        unsigned long delay = 0;
  38
  39        if (unlikely(panic_heartbeats)) {
  40                led_set_brightness(led_cdev, LED_OFF);
  41                return;
  42        }
  43
  44        /* acts like an actual heart beat -- ie thump-thump-pause... */
  45        switch (heartbeat_data->phase) {
  46        case 0:
  47                /*
  48                 * The hyperbolic function below modifies the
  49                 * heartbeat period length in dependency of the
  50                 * current (1min) load. It goes through the points
  51                 * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300.
  52                 */
  53                heartbeat_data->period = 300 +
  54                        (6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
  55                heartbeat_data->period =
  56                        msecs_to_jiffies(heartbeat_data->period);
  57                delay = msecs_to_jiffies(70);
  58                heartbeat_data->phase++;
  59                brightness = led_cdev->max_brightness;
  60                break;
  61        case 1:
  62                delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
  63                heartbeat_data->phase++;
  64                break;
  65        case 2:
  66                delay = msecs_to_jiffies(70);
  67                heartbeat_data->phase++;
  68                brightness = led_cdev->max_brightness;
  69                break;
  70        default:
  71                delay = heartbeat_data->period - heartbeat_data->period / 4 -
  72                        msecs_to_jiffies(70);
  73                heartbeat_data->phase = 0;
  74                break;
  75        }
  76
  77        __led_set_brightness(led_cdev, brightness);
  78        mod_timer(&heartbeat_data->timer, jiffies + delay);
  79}
  80
  81static void heartbeat_trig_activate(struct led_classdev *led_cdev)
  82{
  83        struct heartbeat_trig_data *heartbeat_data;
  84
  85        heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL);
  86        if (!heartbeat_data)
  87                return;
  88
  89        led_cdev->trigger_data = heartbeat_data;
  90        setup_timer(&heartbeat_data->timer,
  91                    led_heartbeat_function, (unsigned long) led_cdev);
  92        heartbeat_data->phase = 0;
  93        led_heartbeat_function(heartbeat_data->timer.data);
  94        led_cdev->activated = true;
  95}
  96
  97static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
  98{
  99        struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
 100
 101        if (led_cdev->activated) {
 102                del_timer_sync(&heartbeat_data->timer);
 103                kfree(heartbeat_data);
 104                led_cdev->activated = false;
 105        }
 106}
 107
 108static struct led_trigger heartbeat_led_trigger = {
 109        .name     = "heartbeat",
 110        .activate = heartbeat_trig_activate,
 111        .deactivate = heartbeat_trig_deactivate,
 112};
 113
 114static int heartbeat_reboot_notifier(struct notifier_block *nb,
 115                                     unsigned long code, void *unused)
 116{
 117        led_trigger_unregister(&heartbeat_led_trigger);
 118        return NOTIFY_DONE;
 119}
 120
 121static int heartbeat_panic_notifier(struct notifier_block *nb,
 122                                     unsigned long code, void *unused)
 123{
 124        panic_heartbeats = 1;
 125        return NOTIFY_DONE;
 126}
 127
 128static struct notifier_block heartbeat_reboot_nb = {
 129        .notifier_call = heartbeat_reboot_notifier,
 130};
 131
 132static struct notifier_block heartbeat_panic_nb = {
 133        .notifier_call = heartbeat_panic_notifier,
 134};
 135
 136static int __init heartbeat_trig_init(void)
 137{
 138        int rc = led_trigger_register(&heartbeat_led_trigger);
 139
 140        if (!rc) {
 141                atomic_notifier_chain_register(&panic_notifier_list,
 142                                               &heartbeat_panic_nb);
 143                register_reboot_notifier(&heartbeat_reboot_nb);
 144        }
 145        return rc;
 146}
 147
 148static void __exit heartbeat_trig_exit(void)
 149{
 150        unregister_reboot_notifier(&heartbeat_reboot_nb);
 151        atomic_notifier_chain_unregister(&panic_notifier_list,
 152                                         &heartbeat_panic_nb);
 153        led_trigger_unregister(&heartbeat_led_trigger);
 154}
 155
 156module_init(heartbeat_trig_init);
 157module_exit(heartbeat_trig_exit);
 158
 159MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 160MODULE_DESCRIPTION("Heartbeat LED trigger");
 161MODULE_LICENSE("GPL");
 162
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