tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Kernel Panic LED Trigger
4 *
5 * Copyright 2016 Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
6 */
7
8#include <linux/kernel.h>
9#include <linux/init.h>
10#include <linux/notifier.h>
11#include <linux/leds.h>
12#include "../leds.h"
13
14static struct led_trigger *trigger;
15
16/*
17 * This is called in a special context by the atomic panic
18 * notifier. This means the trigger can be changed without
19 * worrying about locking.
20 */
21static void led_trigger_set_panic(struct led_classdev *led_cdev)
22{
23 struct led_trigger *trig;
24
25 list_for_each_entry(trig, &trigger_list, next_trig) {
26 if (strcmp("panic", trig->name))
27 continue;
28 if (led_cdev->trigger)
29 list_del(&led_cdev->trig_list);
30 list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
31
32 /* Avoid the delayed blink path */
33 led_cdev->blink_delay_on = 0;
34 led_cdev->blink_delay_off = 0;
35
36 led_cdev->trigger = trig;
37 if (trig->activate)
38 trig->activate(led_cdev);
39 break;
40 }
41}
42
43static int led_trigger_panic_notifier(struct notifier_block *nb,
44 unsigned long code, void *unused)
45{
46 struct led_classdev *led_cdev;
47
48 list_for_each_entry(led_cdev, &leds_list, node)
49 if (led_cdev->flags & LED_PANIC_INDICATOR)
50 led_trigger_set_panic(led_cdev);
51 return NOTIFY_DONE;
52}
53
54static struct notifier_block led_trigger_panic_nb = {
55 .notifier_call = led_trigger_panic_notifier,
56};
57
58static long led_panic_blink(int state)
59{
60 led_trigger_event(trigger, state ? LED_FULL : LED_OFF);
61 return 0;
62}
63
64static int __init ledtrig_panic_init(void)
65{
66 atomic_notifier_chain_register(&panic_notifier_list,
67 &led_trigger_panic_nb);
68
69 led_trigger_register_simple("panic", &trigger);
70 panic_blink = led_panic_blink;
71 return 0;
72}
73device_initcall(ledtrig_panic_init);