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 struct led_trigger *trig;
25
26 list_for_each_entry(trig, &trigger_list, next_trig) {
27 if (strcmp("panic", trig->name))
28 continue;
29 if (led_cdev->trigger)
30 list_del(&led_cdev->trig_list);
31 list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
32
33 /* Avoid the delayed blink path */
34 led_cdev->blink_delay_on = 0;
35 led_cdev->blink_delay_off = 0;
36
37 led_cdev->trigger = trig;
38 if (trig->activate)
39 trig->activate(led_cdev);
40 break;
41 }
42 }
43
led_trigger_panic_notifier(struct notifier_block * nb,unsigned long code,void * unused)44 static int led_trigger_panic_notifier(struct notifier_block *nb,
45 unsigned long code, void *unused)
46 {
47 struct led_classdev *led_cdev;
48
49 list_for_each_entry(led_cdev, &leds_list, node)
50 if (led_cdev->flags & LED_PANIC_INDICATOR)
51 led_trigger_set_panic(led_cdev);
52 return NOTIFY_DONE;
53 }
54
55 static struct notifier_block led_trigger_panic_nb = {
56 .notifier_call = led_trigger_panic_notifier,
57 };
58
led_panic_blink(int state)59 static long led_panic_blink(int state)
60 {
61 led_trigger_event(trigger, state ? LED_FULL : LED_OFF);
62 return 0;
63 }
64
ledtrig_panic_init(void)65 static int __init ledtrig_panic_init(void)
66 {
67 atomic_notifier_chain_register(&panic_notifier_list,
68 &led_trigger_panic_nb);
69
70 led_trigger_register_simple("panic", &trigger);
71 panic_blink = led_panic_blink;
72 return 0;
73 }
74 device_initcall(ledtrig_panic_init);
75