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 14 static 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 */ 21 static 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 43 static 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 54 static struct notifier_block led_trigger_panic_nb = { 55 .notifier_call = led_trigger_panic_notifier, 56 }; 57 58 static long led_panic_blink(int state) 59 { 60 led_trigger_event(trigger, state ? LED_FULL : LED_OFF); 61 return 0; 62 } 63 64 static 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 } 73 device_initcall(ledtrig_panic_init); 74