drivers/leds/trigger/ledtrig-input-events.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Input Events LED trigger
   4  *
   5  * Copyright (C) 2024 Hans de Goede <hansg@kernel.org>
   6  */
   7
   8 #include <linux/input.h>
   9 #include <linux/jiffies.h>
  10 #include <linux/leds.h>
  11 #include <linux/module.h>
  12 #include <linux/moduleparam.h>
  13 #include <linux/slab.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/workqueue.h>
  16 #include "../leds.h"
  17
  18 static unsigned long led_off_delay_ms = 5000;
  19 module_param(led_off_delay_ms, ulong, 0644);
  20 MODULE_PARM_DESC(led_off_delay_ms,
  21         "Specify delay in ms for turning LEDs off after last input event");
  22
  23 static struct input_events_data {
  24         struct delayed_work work;
  25         spinlock_t lock;
  26         /* To avoid repeatedly setting the brightness while there are events */
  27         bool led_on;
  28         unsigned long led_off_time;
  29 } input_events_data;
  30
  31 static struct led_trigger *input_events_led_trigger;
  32
  33 static void led_input_events_work(struct work_struct *work)
  34 {
  35         struct input_events_data *data =
  36                 container_of(work, struct input_events_data, work.work);
  37
  38         spin_lock_irq(&data->lock);
  39
  40         /*
  41          * This time_after_eq() check avoids a race where this work starts
  42          * running before a new event pushed led_off_time back.
  43          */
  44         if (time_after_eq(jiffies, data->led_off_time)) {
  45                 led_trigger_event(input_events_led_trigger, LED_OFF);
  46                 data->led_on = false;
  47         }
  48
  49         spin_unlock_irq(&data->lock);
  50 }
  51
  52 static void input_events_event(struct input_handle *handle, unsigned int type,
  53                                unsigned int code, int val)
  54 {
  55         struct input_events_data *data = &input_events_data;
  56         unsigned long led_off_delay = msecs_to_jiffies(led_off_delay_ms);
  57         unsigned long flags;
  58
  59         spin_lock_irqsave(&data->lock, flags);
  60
  61         if (!data->led_on) {
  62                 led_trigger_event(input_events_led_trigger, LED_FULL);
  63                 data->led_on = true;
  64         }
  65         data->led_off_time = jiffies + led_off_delay;
  66
  67         spin_unlock_irqrestore(&data->lock, flags);
  68
  69         mod_delayed_work(system_wq, &data->work, led_off_delay);
  70 }
  71
  72 static int input_events_connect(struct input_handler *handler, struct input_dev *dev,
  73                                 const struct input_device_id *id)
  74 {
  75         struct input_handle *handle;
  76         int ret;
  77
  78         handle = kzalloc(sizeof(*handle), GFP_KERNEL);
  79         if (!handle)
  80                 return -ENOMEM;
  81
  82         handle->dev = dev;
  83         handle->handler = handler;
  84         handle->name = KBUILD_MODNAME;
  85
  86         ret = input_register_handle(handle);
  87         if (ret)
  88                 goto err_free_handle;
  89
  90         ret = input_open_device(handle);
  91         if (ret)
  92                 goto err_unregister_handle;
  93
  94         return 0;
  95
  96 err_unregister_handle:
  97         input_unregister_handle(handle);
  98 err_free_handle:
  99         kfree(handle);
 100         return ret;
 101 }
 102
 103 static void input_events_disconnect(struct input_handle *handle)
 104 {
 105         input_close_device(handle);
 106         input_unregister_handle(handle);
 107         kfree(handle);
 108 }
 109
 110 static const struct input_device_id input_events_ids[] = {
 111         {
 112                 .flags = INPUT_DEVICE_ID_MATCH_EVBIT,
 113                 .evbit = { BIT_MASK(EV_KEY) },
 114         },
 115         {
 116                 .flags = INPUT_DEVICE_ID_MATCH_EVBIT,
 117                 .evbit = { BIT_MASK(EV_REL) },
 118         },
 119         {
 120                 .flags = INPUT_DEVICE_ID_MATCH_EVBIT,
 121                 .evbit = { BIT_MASK(EV_ABS) },
 122         },
 123         { }
 124 };
 125
 126 static struct input_handler input_events_handler = {
 127         .name = KBUILD_MODNAME,
 128         .event = input_events_event,
 129         .connect = input_events_connect,
 130         .disconnect = input_events_disconnect,
 131         .id_table = input_events_ids,
 132 };
 133
 134 static int __init input_events_init(void)
 135 {
 136         int ret;
 137
 138         INIT_DELAYED_WORK(&input_events_data.work, led_input_events_work);
 139         spin_lock_init(&input_events_data.lock);
 140
 141         led_trigger_register_simple("input-events", &input_events_led_trigger);
 142
 143         ret = input_register_handler(&input_events_handler);
 144         if (ret) {
 145                 led_trigger_unregister_simple(input_events_led_trigger);
 146                 return ret;
 147         }
 148
 149         return 0;
 150 }
 151
 152 static void __exit input_events_exit(void)
 153 {
 154         input_unregister_handler(&input_events_handler);
 155         cancel_delayed_work_sync(&input_events_data.work);
 156         led_trigger_unregister_simple(input_events_led_trigger);
 157 }
 158
 159 module_init(input_events_init);
 160 module_exit(input_events_exit);
 161
 162 MODULE_AUTHOR("Hans de Goede <hansg@kernel.org>");
 163 MODULE_DESCRIPTION("Input Events LED trigger");
 164 MODULE_LICENSE("GPL");
 165 MODULE_ALIAS("ledtrig:input-events");