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 static int panic_heartbeats;
  25
  26 struct heartbeat_trig_data {
  27         unsigned int phase;
  28         unsigned int period;
  29         struct timer_list timer;
  30 };
  31
  32 static 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
  81 static 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
  97 static 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
 108 static struct led_trigger heartbeat_led_trigger = {
 109         .name     = "heartbeat",
 110         .activate = heartbeat_trig_activate,
 111         .deactivate = heartbeat_trig_deactivate,
 112 };
 113
 114 static 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
 121 static 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
 128 static struct notifier_block heartbeat_reboot_nb = {
 129         .notifier_call = heartbeat_reboot_notifier,
 130 };
 131
 132 static struct notifier_block heartbeat_panic_nb = {
 133         .notifier_call = heartbeat_panic_notifier,
 134 };
 135
 136 static 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
 148 static 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
 156 module_init(heartbeat_trig_init);
 157 module_exit(heartbeat_trig_exit);
 158
 159 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 160 MODULE_DESCRIPTION("Heartbeat LED trigger");
 161 MODULE_LICENSE("GPL");