drivers/leds/trigger/ledtrig-heartbeat.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * LED Heartbeat Trigger
   4  *
   5  * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
   6  *
   7  * Based on Richard Purdie's ledtrig-timer.c and some arch's
   8  * CONFIG_HEARTBEAT code.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/init.h>
  14 #include <linux/panic_notifier.h>
  15 #include <linux/slab.h>
  16 #include <linux/timer.h>
  17 #include <linux/sched.h>
  18 #include <linux/sched/loadavg.h>
  19 #include <linux/leds.h>
  20 #include <linux/reboot.h>
  21 #include "../leds.h"
  22
  23 static int panic_heartbeats;
  24
  25 struct heartbeat_trig_data {
  26         struct led_classdev *led_cdev;
  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(struct timer_list *t)
  34 {
  35         struct heartbeat_trig_data *heartbeat_data =
  36                 from_timer(heartbeat_data, t, timer);
  37         struct led_classdev *led_cdev;
  38         unsigned long brightness = LED_OFF;
  39         unsigned long delay = 0;
  40
  41         led_cdev = heartbeat_data->led_cdev;
  42
  43         if (unlikely(panic_heartbeats)) {
  44                 led_set_brightness_nosleep(led_cdev, LED_OFF);
  45                 return;
  46         }
  47
  48         if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags))
  49                 led_cdev->blink_brightness = led_cdev->new_blink_brightness;
  50
  51         /* acts like an actual heart beat -- ie thump-thump-pause... */
  52         switch (heartbeat_data->phase) {
  53         case 0:
  54                 /*
  55                  * The hyperbolic function below modifies the
  56                  * heartbeat period length in dependency of the
  57                  * current (1min) load. It goes through the points
  58                  * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300.
  59                  */
  60                 heartbeat_data->period = 300 +
  61                         (6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
  62                 heartbeat_data->period =
  63                         msecs_to_jiffies(heartbeat_data->period);
  64                 delay = msecs_to_jiffies(70);
  65                 heartbeat_data->phase++;
  66                 if (!heartbeat_data->invert)
  67                         brightness = led_cdev->blink_brightness;
  68                 break;
  69         case 1:
  70                 delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
  71                 heartbeat_data->phase++;
  72                 if (heartbeat_data->invert)
  73                         brightness = led_cdev->blink_brightness;
  74                 break;
  75         case 2:
  76                 delay = msecs_to_jiffies(70);
  77                 heartbeat_data->phase++;
  78                 if (!heartbeat_data->invert)
  79                         brightness = led_cdev->blink_brightness;
  80                 break;
  81         default:
  82                 delay = heartbeat_data->period - heartbeat_data->period / 4 -
  83                         msecs_to_jiffies(70);
  84                 heartbeat_data->phase = 0;
  85                 if (heartbeat_data->invert)
  86                         brightness = led_cdev->blink_brightness;
  87                 break;
  88         }
  89
  90         led_set_brightness_nosleep(led_cdev, brightness);
  91         mod_timer(&heartbeat_data->timer, jiffies + delay);
  92 }
  93
  94 static ssize_t led_invert_show(struct device *dev,
  95                 struct device_attribute *attr, char *buf)
  96 {
  97         struct heartbeat_trig_data *heartbeat_data =
  98                 led_trigger_get_drvdata(dev);
  99
 100         return sprintf(buf, "%u\n", heartbeat_data->invert);
 101 }
 102
 103 static ssize_t led_invert_store(struct device *dev,
 104                 struct device_attribute *attr, const char *buf, size_t size)
 105 {
 106         struct heartbeat_trig_data *heartbeat_data =
 107                 led_trigger_get_drvdata(dev);
 108         unsigned long state;
 109         int ret;
 110
 111         ret = kstrtoul(buf, 0, &state);
 112         if (ret)
 113                 return ret;
 114
 115         heartbeat_data->invert = !!state;
 116
 117         return size;
 118 }
 119
 120 static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);
 121
 122 static struct attribute *heartbeat_trig_attrs[] = {
 123         &dev_attr_invert.attr,
 124         NULL
 125 };
 126 ATTRIBUTE_GROUPS(heartbeat_trig);
 127
 128 static int heartbeat_trig_activate(struct led_classdev *led_cdev)
 129 {
 130         struct heartbeat_trig_data *heartbeat_data;
 131
 132         heartbeat_data = kzalloc(sizeof(*heartbeat_data), GFP_KERNEL);
 133         if (!heartbeat_data)
 134                 return -ENOMEM;
 135
 136         led_set_trigger_data(led_cdev, heartbeat_data);
 137         heartbeat_data->led_cdev = led_cdev;
 138
 139         timer_setup(&heartbeat_data->timer, led_heartbeat_function, 0);
 140         heartbeat_data->phase = 0;
 141         if (!led_cdev->blink_brightness)
 142                 led_cdev->blink_brightness = led_cdev->max_brightness;
 143         led_heartbeat_function(&heartbeat_data->timer);
 144         set_bit(LED_BLINK_SW, &led_cdev->work_flags);
 145
 146         return 0;
 147 }
 148
 149 static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
 150 {
 151         struct heartbeat_trig_data *heartbeat_data =
 152                 led_get_trigger_data(led_cdev);
 153
 154         del_timer_sync(&heartbeat_data->timer);
 155         kfree(heartbeat_data);
 156         clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
 157 }
 158
 159 static struct led_trigger heartbeat_led_trigger = {
 160         .name     = "heartbeat",
 161         .activate = heartbeat_trig_activate,
 162         .deactivate = heartbeat_trig_deactivate,
 163         .groups = heartbeat_trig_groups,
 164 };
 165
 166 static int heartbeat_reboot_notifier(struct notifier_block *nb,
 167                                      unsigned long code, void *unused)
 168 {
 169         led_trigger_unregister(&heartbeat_led_trigger);
 170         return NOTIFY_DONE;
 171 }
 172
 173 static int heartbeat_panic_notifier(struct notifier_block *nb,
 174                                      unsigned long code, void *unused)
 175 {
 176         panic_heartbeats = 1;
 177         return NOTIFY_DONE;
 178 }
 179
 180 static struct notifier_block heartbeat_reboot_nb = {
 181         .notifier_call = heartbeat_reboot_notifier,
 182 };
 183
 184 static struct notifier_block heartbeat_panic_nb = {
 185         .notifier_call = heartbeat_panic_notifier,
 186 };
 187
 188 static int __init heartbeat_trig_init(void)
 189 {
 190         int rc = led_trigger_register(&heartbeat_led_trigger);
 191
 192         if (!rc) {
 193                 atomic_notifier_chain_register(&panic_notifier_list,
 194                                                &heartbeat_panic_nb);
 195                 register_reboot_notifier(&heartbeat_reboot_nb);
 196         }
 197         return rc;
 198 }
 199
 200 static void __exit heartbeat_trig_exit(void)
 201 {
 202         unregister_reboot_notifier(&heartbeat_reboot_nb);
 203         atomic_notifier_chain_unregister(&panic_notifier_list,
 204                                          &heartbeat_panic_nb);
 205         led_trigger_unregister(&heartbeat_led_trigger);
 206 }
 207
 208 module_init(heartbeat_trig_init);
 209 module_exit(heartbeat_trig_exit);
 210
 211 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 212 MODULE_DESCRIPTION("Heartbeat LED trigger");
 213 MODULE_LICENSE("GPL v2");