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/panic_notifier.h>
12 #include <linux/leds.h>
13 #include "../leds.h"
14
15 static struct led_trigger *trigger;
16
17 /*
18 * This is called in a special context by the atomic panic
19 * notifier. This means the trigger can be changed without
20 * worrying about locking.
21 */
led_trigger_set_panic(struct led_classdev * led_cdev)22 static void led_trigger_set_panic(struct led_classdev *led_cdev)
23 {
24 if (led_cdev->trigger)
25 list_del(&led_cdev->trig_list);
26 list_add_tail(&led_cdev->trig_list, &trigger->led_cdevs);
27
28 /* Avoid the delayed blink path */
29 led_cdev->blink_delay_on = 0;
30 led_cdev->blink_delay_off = 0;
31
32 led_cdev->trigger = trigger;
33 }
34
led_trigger_panic_notifier(struct notifier_block * nb,unsigned long code,void * unused)35 static int led_trigger_panic_notifier(struct notifier_block *nb,
36 unsigned long code, void *unused)
37 {
38 struct led_classdev *led_cdev;
39
40 list_for_each_entry(led_cdev, &leds_list, node)
41 if (led_cdev->flags & LED_PANIC_INDICATOR)
42 led_trigger_set_panic(led_cdev);
43 return NOTIFY_DONE;
44 }
45
46 static struct notifier_block led_trigger_panic_nb = {
47 .notifier_call = led_trigger_panic_notifier,
48 };
49
led_panic_blink(int state)50 static long led_panic_blink(int state)
51 {
52 led_trigger_event(trigger, state ? LED_FULL : LED_OFF);
53 return 0;
54 }
55
ledtrig_panic_init(void)56 static int __init ledtrig_panic_init(void)
57 {
58 led_trigger_register_simple("panic", &trigger);
59 if (!trigger)
60 return -ENOMEM;
61
62 atomic_notifier_chain_register(&panic_notifier_list,
63 &led_trigger_panic_nb);
64
65 panic_blink = led_panic_blink;
66 return 0;
67 }
68 device_initcall(ledtrig_panic_init);
69