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 */ 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 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 59 static long led_panic_blink(int state) 60 { 61 led_trigger_event(trigger, state ? LED_FULL : LED_OFF); 62 return 0; 63 } 64 65 static int __init ledtrig_panic_init(void) 66 { 67 led_trigger_register_simple("panic", &trigger); 68 if (!trigger) 69 return -ENOMEM; 70 71 atomic_notifier_chain_register(&panic_notifier_list, 72 &led_trigger_panic_nb); 73 74 panic_blink = led_panic_blink; 75 return 0; 76 } 77 device_initcall(ledtrig_panic_init); 78