drivers/leds/trigger/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         unsigned int invert;
  31 };
  32
  33 static void led_heartbeat_function(unsigned long data)
  34 {
  35         struct led_classdev *led_cdev = (struct led_classdev *) data;
  36         struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
  37         unsigned long brightness = LED_OFF;
  38         unsigned long delay = 0;
  39
  40         if (unlikely(panic_heartbeats)) {
  41                 led_set_brightness(led_cdev, LED_OFF);
  42                 return;
  43         }
  44
  45         /* acts like an actual heart beat -- ie thump-thump-pause... */
  46         switch (heartbeat_data->phase) {
  47         case 0:
  48                 /*
  49                  * The hyperbolic function below modifies the
  50                  * heartbeat period length in dependency of the
  51                  * current (1min) load. It goes through the points
  52                  * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300.
  53                  */
  54                 heartbeat_data->period = 300 +
  55                         (6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
  56                 heartbeat_data->period =
  57                         msecs_to_jiffies(heartbeat_data->period);
  58                 delay = msecs_to_jiffies(70);
  59                 heartbeat_data->phase++;
  60                 if (!heartbeat_data->invert)
  61                         brightness = led_cdev->max_brightness;
  62                 break;
  63         case 1:
  64                 delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
  65                 heartbeat_data->phase++;
  66                 if (heartbeat_data->invert)
  67                         brightness = led_cdev->max_brightness;
  68                 break;
  69         case 2:
  70                 delay = msecs_to_jiffies(70);
  71                 heartbeat_data->phase++;
  72                 if (!heartbeat_data->invert)
  73                         brightness = led_cdev->max_brightness;
  74                 break;
  75         default:
  76                 delay = heartbeat_data->period - heartbeat_data->period / 4 -
  77                         msecs_to_jiffies(70);
  78                 heartbeat_data->phase = 0;
  79                 if (heartbeat_data->invert)
  80                         brightness = led_cdev->max_brightness;
  81                 break;
  82         }
  83
  84         led_set_brightness_async(led_cdev, brightness);
  85         mod_timer(&heartbeat_data->timer, jiffies + delay);
  86 }
  87
  88 static ssize_t led_invert_show(struct device *dev,
  89                 struct device_attribute *attr, char *buf)
  90 {
  91         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  92         struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
  93
  94         return sprintf(buf, "%u\n", heartbeat_data->invert);
  95 }
  96
  97 static ssize_t led_invert_store(struct device *dev,
  98                 struct device_attribute *attr, const char *buf, size_t size)
  99 {
 100         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 101         struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
 102         unsigned long state;
 103         int ret;
 104
 105         ret = kstrtoul(buf, 0, &state);
 106         if (ret)
 107                 return ret;
 108
 109         heartbeat_data->invert = !!state;
 110
 111         return size;
 112 }
 113
 114 static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);
 115
 116 static void heartbeat_trig_activate(struct led_classdev *led_cdev)
 117 {
 118         struct heartbeat_trig_data *heartbeat_data;
 119         int rc;
 120
 121         heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL);
 122         if (!heartbeat_data)
 123                 return;
 124
 125         led_cdev->trigger_data = heartbeat_data;
 126         rc = device_create_file(led_cdev->dev, &dev_attr_invert);
 127         if (rc) {
 128                 kfree(led_cdev->trigger_data);
 129                 return;
 130         }
 131
 132         setup_timer(&heartbeat_data->timer,
 133                     led_heartbeat_function, (unsigned long) led_cdev);
 134         heartbeat_data->phase = 0;
 135         led_heartbeat_function(heartbeat_data->timer.data);
 136         led_cdev->activated = true;
 137 }
 138
 139 static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
 140 {
 141         struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
 142
 143         if (led_cdev->activated) {
 144                 del_timer_sync(&heartbeat_data->timer);
 145                 device_remove_file(led_cdev->dev, &dev_attr_invert);
 146                 kfree(heartbeat_data);
 147                 led_cdev->activated = false;
 148         }
 149 }
 150
 151 static struct led_trigger heartbeat_led_trigger = {
 152         .name     = "heartbeat",
 153         .activate = heartbeat_trig_activate,
 154         .deactivate = heartbeat_trig_deactivate,
 155 };
 156
 157 static int heartbeat_reboot_notifier(struct notifier_block *nb,
 158                                      unsigned long code, void *unused)
 159 {
 160         led_trigger_unregister(&heartbeat_led_trigger);
 161         return NOTIFY_DONE;
 162 }
 163
 164 static int heartbeat_panic_notifier(struct notifier_block *nb,
 165                                      unsigned long code, void *unused)
 166 {
 167         panic_heartbeats = 1;
 168         return NOTIFY_DONE;
 169 }
 170
 171 static struct notifier_block heartbeat_reboot_nb = {
 172         .notifier_call = heartbeat_reboot_notifier,
 173 };
 174
 175 static struct notifier_block heartbeat_panic_nb = {
 176         .notifier_call = heartbeat_panic_notifier,
 177 };
 178
 179 static int __init heartbeat_trig_init(void)
 180 {
 181         int rc = led_trigger_register(&heartbeat_led_trigger);
 182
 183         if (!rc) {
 184                 atomic_notifier_chain_register(&panic_notifier_list,
 185                                                &heartbeat_panic_nb);
 186                 register_reboot_notifier(&heartbeat_reboot_nb);
 187         }
 188         return rc;
 189 }
 190
 191 static void __exit heartbeat_trig_exit(void)
 192 {
 193         unregister_reboot_notifier(&heartbeat_reboot_nb);
 194         atomic_notifier_chain_unregister(&panic_notifier_list,
 195                                          &heartbeat_panic_nb);
 196         led_trigger_unregister(&heartbeat_led_trigger);
 197 }
 198
 199 module_init(heartbeat_trig_init);
 200 module_exit(heartbeat_trig_exit);
 201
 202 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 203 MODULE_DESCRIPTION("Heartbeat LED trigger");
 204 MODULE_LICENSE("GPL");