| xj | b04a402 | 2021-11-25 15:01:52 +0800 | [diff] [blame] | 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); |