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/sched/loadavg.h>
  21 #include <linux/leds.h>
  22 #include <linux/reboot.h>
  23 #include "../leds.h"
  24
  25 static int panic_heartbeats;
  26
  27 struct heartbeat_trig_data {
  28         struct led_classdev *led_cdev;
  29         unsigned int phase;
  30         unsigned int period;
  31         struct timer_list timer;
  32         unsigned int invert;
  33 };
  34
  35 static void led_heartbeat_function(struct timer_list *t)
  36 {
  37         struct heartbeat_trig_data *heartbeat_data =
  38                 from_timer(heartbeat_data, t, timer);
  39         struct led_classdev *led_cdev;
  40         unsigned long brightness = LED_OFF;
  41         unsigned long delay = 0;
  42
  43         led_cdev = heartbeat_data->led_cdev;
  44
  45         if (unlikely(panic_heartbeats)) {
  46                 led_set_brightness_nosleep(led_cdev, LED_OFF);
  47                 return;
  48         }
  49
  50         if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags))
  51                 led_cdev->blink_brightness = led_cdev->new_blink_brightness;
  52
  53         /* acts like an actual heart beat -- ie thump-thump-pause... */
  54         switch (heartbeat_data->phase) {
  55         case 0:
  56                 /*
  57                  * The hyperbolic function below modifies the
  58                  * heartbeat period length in dependency of the
  59                  * current (1min) load. It goes through the points
  60                  * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300.
  61                  */
  62                 heartbeat_data->period = 300 +
  63                         (6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
  64                 heartbeat_data->period =
  65                         msecs_to_jiffies(heartbeat_data->period);
  66                 delay = msecs_to_jiffies(70);
  67                 heartbeat_data->phase++;
  68                 if (!heartbeat_data->invert)
  69                         brightness = led_cdev->blink_brightness;
  70                 break;
  71         case 1:
  72                 delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
  73                 heartbeat_data->phase++;
  74                 if (heartbeat_data->invert)
  75                         brightness = led_cdev->blink_brightness;
  76                 break;
  77         case 2:
  78                 delay = msecs_to_jiffies(70);
  79                 heartbeat_data->phase++;
  80                 if (!heartbeat_data->invert)
  81                         brightness = led_cdev->blink_brightness;
  82                 break;
  83         default:
  84                 delay = heartbeat_data->period - heartbeat_data->period / 4 -
  85                         msecs_to_jiffies(70);
  86                 heartbeat_data->phase = 0;
  87                 if (heartbeat_data->invert)
  88                         brightness = led_cdev->blink_brightness;
  89                 break;
  90         }
  91
  92         led_set_brightness_nosleep(led_cdev, brightness);
  93         mod_timer(&heartbeat_data->timer, jiffies + delay);
  94 }
  95
  96 static ssize_t led_invert_show(struct device *dev,
  97                 struct device_attribute *attr, char *buf)
  98 {
  99         struct heartbeat_trig_data *heartbeat_data =
 100                 led_trigger_get_drvdata(dev);
 101
 102         return sprintf(buf, "%u\n", heartbeat_data->invert);
 103 }
 104
 105 static ssize_t led_invert_store(struct device *dev,
 106                 struct device_attribute *attr, const char *buf, size_t size)
 107 {
 108         struct heartbeat_trig_data *heartbeat_data =
 109                 led_trigger_get_drvdata(dev);
 110         unsigned long state;
 111         int ret;
 112
 113         ret = kstrtoul(buf, 0, &state);
 114         if (ret)
 115                 return ret;
 116
 117         heartbeat_data->invert = !!state;
 118
 119         return size;
 120 }
 121
 122 static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);
 123
 124 static struct attribute *heartbeat_trig_attrs[] = {
 125         &dev_attr_invert.attr,
 126         NULL
 127 };
 128 ATTRIBUTE_GROUPS(heartbeat_trig);
 129
 130 static int heartbeat_trig_activate(struct led_classdev *led_cdev)
 131 {
 132         struct heartbeat_trig_data *heartbeat_data;
 133
 134         heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL);
 135         if (!heartbeat_data)
 136                 return -ENOMEM;
 137
 138         led_set_trigger_data(led_cdev, heartbeat_data);
 139         heartbeat_data->led_cdev = led_cdev;
 140
 141         timer_setup(&heartbeat_data->timer, led_heartbeat_function, 0);
 142         heartbeat_data->phase = 0;
 143         if (!led_cdev->blink_brightness)
 144                 led_cdev->blink_brightness = led_cdev->max_brightness;
 145         led_heartbeat_function(&heartbeat_data->timer);
 146         set_bit(LED_BLINK_SW, &led_cdev->work_flags);
 147
 148         return 0;
 149 }
 150
 151 static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
 152 {
 153         struct heartbeat_trig_data *heartbeat_data =
 154                 led_get_trigger_data(led_cdev);
 155
 156         del_timer_sync(&heartbeat_data->timer);
 157         kfree(heartbeat_data);
 158         clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
 159 }
 160
 161 static struct led_trigger heartbeat_led_trigger = {
 162         .name     = "heartbeat",
 163         .activate = heartbeat_trig_activate,
 164         .deactivate = heartbeat_trig_deactivate,
 165         .groups = heartbeat_trig_groups,
 166 };
 167
 168 static int heartbeat_reboot_notifier(struct notifier_block *nb,
 169                                      unsigned long code, void *unused)
 170 {
 171         led_trigger_unregister(&heartbeat_led_trigger);
 172         return NOTIFY_DONE;
 173 }
 174
 175 static int heartbeat_panic_notifier(struct notifier_block *nb,
 176                                      unsigned long code, void *unused)
 177 {
 178         panic_heartbeats = 1;
 179         return NOTIFY_DONE;
 180 }
 181
 182 static struct notifier_block heartbeat_reboot_nb = {
 183         .notifier_call = heartbeat_reboot_notifier,
 184 };
 185
 186 static struct notifier_block heartbeat_panic_nb = {
 187         .notifier_call = heartbeat_panic_notifier,
 188 };
 189
 190 static int __init heartbeat_trig_init(void)
 191 {
 192         int rc = led_trigger_register(&heartbeat_led_trigger);
 193
 194         if (!rc) {
 195                 atomic_notifier_chain_register(&panic_notifier_list,
 196                                                &heartbeat_panic_nb);
 197                 register_reboot_notifier(&heartbeat_reboot_nb);
 198         }
 199         return rc;
 200 }
 201
 202 static void __exit heartbeat_trig_exit(void)
 203 {
 204         unregister_reboot_notifier(&heartbeat_reboot_nb);
 205         atomic_notifier_chain_unregister(&panic_notifier_list,
 206                                          &heartbeat_panic_nb);
 207         led_trigger_unregister(&heartbeat_led_trigger);
 208 }
 209
 210 module_init(heartbeat_trig_init);
 211 module_exit(heartbeat_trig_exit);
 212
 213 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 214 MODULE_DESCRIPTION("Heartbeat LED trigger");
 215 MODULE_LICENSE("GPL v2");