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