// SPDX-License-Identifier: GPL-2.0-only /* * Kernel Panic LED Trigger * * Copyright 2016 Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> */ #include <linux/kernel.h> #include <linux/init.h> #include <linux/notifier.h> #include <linux/leds.h> #include "../leds.h" static struct led_trigger *trigger; /* * This is called in a special context by the atomic panic * notifier. This means the trigger can be changed without * worrying about locking. */ static void led_trigger_set_panic(struct led_classdev *led_cdev) { struct led_trigger *trig; list_for_each_entry(trig, &trigger_list, next_trig) { if (strcmp("panic", trig->name)) continue; if (led_cdev->trigger) list_del(&led_cdev->trig_list); list_add_tail(&led_cdev->trig_list, &trig->led_cdevs); /* Avoid the delayed blink path */ led_cdev->blink_delay_on = 0; led_cdev->blink_delay_off = 0; led_cdev->trigger = trig; if (trig->activate) trig->activate(led_cdev); break; } } static int led_trigger_panic_notifier(struct notifier_block *nb, unsigned long code, void *unused) { struct led_classdev *led_cdev; list_for_each_entry(led_cdev, &leds_list, node) if (led_cdev->flags & LED_PANIC_INDICATOR) led_trigger_set_panic(led_cdev); return NOTIFY_DONE; } static struct notifier_block led_trigger_panic_nb = { .notifier_call = led_trigger_panic_notifier, }; static long led_panic_blink(int state) { led_trigger_event(trigger, state ? LED_FULL : LED_OFF); return 0; } static int __init ledtrig_panic_init(void) { atomic_notifier_chain_register(&panic_notifier_list, &led_trigger_panic_nb); led_trigger_register_simple("panic", &trigger); panic_blink = led_panic_blink; return 0; } device_initcall(ledtrig_panic_init);