1 /*
2 * Kernel Panic LED Trigger
3 *
4 * Copyright 2016 Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 */
11
12 #include <linux/kernel.h>
13 #include <linux/init.h>
14 #include <linux/notifier.h>
15 #include <linux/leds.h>
16 #include "../leds.h"
17
18 static struct led_trigger *trigger;
19
20 /*
21 * This is called in a special context by the atomic panic
22 * notifier. This means the trigger can be changed without
23 * worrying about locking.
24 */
led_trigger_set_panic(struct led_classdev * led_cdev)25 static void led_trigger_set_panic(struct led_classdev *led_cdev)
26 {
27 struct led_trigger *trig;
28
29 list_for_each_entry(trig, &trigger_list, next_trig) {
30 if (strcmp("panic", trig->name))
31 continue;
32 if (led_cdev->trigger)
33 list_del(&led_cdev->trig_list);
34 list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
35
36 /* Avoid the delayed blink path */
37 led_cdev->blink_delay_on = 0;
38 led_cdev->blink_delay_off = 0;
39
40 led_cdev->trigger = trig;
41 if (trig->activate)
42 trig->activate(led_cdev);
43 break;
44 }
45 }
46
led_trigger_panic_notifier(struct notifier_block * nb,unsigned long code,void * unused)47 static int led_trigger_panic_notifier(struct notifier_block *nb,
48 unsigned long code, void *unused)
49 {
50 struct led_classdev *led_cdev;
51
52 list_for_each_entry(led_cdev, &leds_list, node)
53 if (led_cdev->flags & LED_PANIC_INDICATOR)
54 led_trigger_set_panic(led_cdev);
55 return NOTIFY_DONE;
56 }
57
58 static struct notifier_block led_trigger_panic_nb = {
59 .notifier_call = led_trigger_panic_notifier,
60 };
61
led_panic_blink(int state)62 static long led_panic_blink(int state)
63 {
64 led_trigger_event(trigger, state ? LED_FULL : LED_OFF);
65 return 0;
66 }
67
ledtrig_panic_init(void)68 static int __init ledtrig_panic_init(void)
69 {
70 atomic_notifier_chain_register(&panic_notifier_list,
71 &led_trigger_panic_nb);
72
73 led_trigger_register_simple("panic", &trigger);
74 panic_blink = led_panic_blink;
75 return 0;
76 }
77 device_initcall(ledtrig_panic_init);
78