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 */ 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 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 62 static long led_panic_blink(int state) 63 { 64 led_trigger_event(trigger, state ? LED_FULL : LED_OFF); 65 return 0; 66 } 67 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