Input: export LEDs as class devices in sysfs

This change creates a new input handler called "leds" that exports LEDs on input
devices as standard LED class devices in sysfs and allows controlling their
state via sysfs or via any of the standard LED triggers. This allows to
re-purpose and reassign LDEs on the keyboards to represent states other
than the standard keyboard states (CapsLock, NumLock, etc).

The old API of controlling input LEDs by writing into /dev/input/eventX
devices is still present and will take precedence over accessing via LEDs
subsystem (i.e. it may override state set by a trigger). If input device is
"grabbed" then requests coming through LED subsystem will be ignored.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Tested-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Samuel Thibault 2015-03-16 21:19:56 -07:00 committed by Dmitry Torokhov
parent cf99289d67
commit f60c8ba77d
5 changed files with 226 additions and 6 deletions

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@ -2,9 +2,6 @@
LED handling under Linux
========================
If you're reading this and thinking about keyboard leds, these are
handled by the input subsystem and the led class is *not* needed.
In its simplest form, the LED class just allows control of LEDs from
userspace. LEDs appear in /sys/class/leds/. The maximum brightness of the
LED is defined in max_brightness file. The brightness file will set the brightness

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@ -25,6 +25,19 @@ config INPUT
if INPUT
config INPUT_LEDS
tristate "Export input device LEDs in sysfs"
depends on LEDS_CLASS
default INPUT
help
Say Y here if you would like to export LEDs on input devices
as standard LED class devices in sysfs.
If unsure, say Y.
To compile this driver as a module, choose M here: the
module will be called input-leds.
config INPUT_FF_MEMLESS
tristate "Support for memoryless force-feedback devices"
help

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@ -12,6 +12,7 @@ obj-$(CONFIG_INPUT_POLLDEV) += input-polldev.o
obj-$(CONFIG_INPUT_SPARSEKMAP) += sparse-keymap.o
obj-$(CONFIG_INPUT_MATRIXKMAP) += matrix-keymap.o
obj-$(CONFIG_INPUT_LEDS) += input-leds.o
obj-$(CONFIG_INPUT_MOUSEDEV) += mousedev.o
obj-$(CONFIG_INPUT_JOYDEV) += joydev.o
obj-$(CONFIG_INPUT_EVDEV) += evdev.o

212
drivers/input/input-leds.c Normal file
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@ -0,0 +1,212 @@
/*
* LED support for the input layer
*
* Copyright 2010-2015 Samuel Thibault <samuel.thibault@ens-lyon.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/leds.h>
#include <linux/input.h>
#if IS_ENABLED(CONFIG_VT)
#define VT_TRIGGER(_name) .trigger = _name
#else
#define VT_TRIGGER(_name) .trigger = NULL
#endif
static const struct {
const char *name;
const char *trigger;
} input_led_info[LED_CNT] = {
[LED_NUML] = { "numlock", VT_TRIGGER("kbd-numlock") },
[LED_CAPSL] = { "capslock", VT_TRIGGER("kbd-capslock") },
[LED_SCROLLL] = { "scrolllock", VT_TRIGGER("kbd-scrolllock") },
[LED_COMPOSE] = { "compose" },
[LED_KANA] = { "kana", VT_TRIGGER("kbd-kanalock") },
[LED_SLEEP] = { "sleep" } ,
[LED_SUSPEND] = { "suspend" },
[LED_MUTE] = { "mute" },
[LED_MISC] = { "misc" },
[LED_MAIL] = { "mail" },
[LED_CHARGING] = { "charging" },
};
struct input_led {
struct led_classdev cdev;
struct input_handle *handle;
unsigned int code; /* One of LED_* constants */
};
struct input_leds {
struct input_handle handle;
unsigned int num_leds;
struct input_led leds[];
};
static enum led_brightness input_leds_brightness_get(struct led_classdev *cdev)
{
struct input_led *led = container_of(cdev, struct input_led, cdev);
struct input_dev *input = led->handle->dev;
return test_bit(led->code, input->led) ? cdev->max_brightness : 0;
}
static void input_leds_brightness_set(struct led_classdev *cdev,
enum led_brightness brightness)
{
struct input_led *led = container_of(cdev, struct input_led, cdev);
input_inject_event(led->handle, EV_LED, led->code, !!brightness);
}
static void input_leds_event(struct input_handle *handle, unsigned int type,
unsigned int code, int value)
{
}
static int input_leds_connect(struct input_handler *handler,
struct input_dev *dev,
const struct input_device_id *id)
{
struct input_leds *leds;
unsigned int num_leds;
unsigned int led_code;
int led_no;
int error;
num_leds = bitmap_weight(dev->ledbit, LED_CNT);
if (!num_leds)
return -ENXIO;
leds = kzalloc(sizeof(*leds) + num_leds * sizeof(*leds->leds),
GFP_KERNEL);
if (!leds)
return -ENOMEM;
leds->num_leds = num_leds;
leds->handle.dev = dev;
leds->handle.handler = handler;
leds->handle.name = "leds";
leds->handle.private = leds;
error = input_register_handle(&leds->handle);
if (error)
goto err_free_mem;
error = input_open_device(&leds->handle);
if (error)
goto err_unregister_handle;
led_no = 0;
for_each_set_bit(led_code, dev->ledbit, LED_CNT) {
struct input_led *led = &leds->leds[led_no];
led->handle = &leds->handle;
led->code = led_code;
if (WARN_ON(!input_led_info[led_code].name))
continue;
led->cdev.name = kasprintf(GFP_KERNEL, "%s::%s",
dev_name(&dev->dev),
input_led_info[led_code].name);
if (!led->cdev.name) {
error = -ENOMEM;
goto err_unregister_leds;
}
led->cdev.max_brightness = 1;
led->cdev.brightness_get = input_leds_brightness_get;
led->cdev.brightness_set = input_leds_brightness_set;
led->cdev.default_trigger = input_led_info[led_code].trigger;
error = led_classdev_register(&dev->dev, &led->cdev);
if (error) {
dev_err(&dev->dev, "failed to register LED %s: %d\n",
led->cdev.name, error);
kfree(led->cdev.name);
goto err_unregister_leds;
}
led_no++;
}
return 0;
err_unregister_leds:
while (--led_no >= 0) {
struct input_led *led = &leds->leds[led_no];
led_classdev_unregister(&led->cdev);
kfree(led->cdev.name);
}
input_close_device(&leds->handle);
err_unregister_handle:
input_unregister_handle(&leds->handle);
err_free_mem:
kfree(leds);
return error;
}
static void input_leds_disconnect(struct input_handle *handle)
{
struct input_leds *leds = handle->private;
int i;
for (i = 0; i < leds->num_leds; i++) {
struct input_led *led = &leds->leds[i];
led_classdev_unregister(&led->cdev);
kfree(led->cdev.name);
}
input_close_device(handle);
input_unregister_handle(handle);
kfree(leds);
}
static const struct input_device_id input_leds_ids[] = {
{
.flags = INPUT_DEVICE_ID_MATCH_EVBIT,
.evbit = { BIT_MASK(EV_LED) },
},
{ },
};
MODULE_DEVICE_TABLE(input, input_leds_ids);
static struct input_handler input_leds_handler = {
.event = input_leds_event,
.connect = input_leds_connect,
.disconnect = input_leds_disconnect,
.name = "leds",
.id_table = input_leds_ids,
};
static int __init input_leds_init(void)
{
return input_register_handler(&input_leds_handler);
}
module_init(input_leds_init);
static void __exit input_leds_exit(void)
{
input_unregister_handler(&input_leds_handler);
}
module_exit(input_leds_exit);
MODULE_AUTHOR("Samuel Thibault <samuel.thibault@ens-lyon.org>");
MODULE_AUTHOR("Dmitry Torokhov <dmitry.torokhov@gmail.com>");
MODULE_DESCRIPTION("Input -> LEDs Bridge");
MODULE_LICENSE("GPL v2");

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@ -11,9 +11,6 @@ menuconfig NEW_LEDS
Say Y to enable Linux LED support. This allows control of supported
LEDs from both userspace and optionally, by kernel events (triggers).
This is not related to standard keyboard LEDs which are controlled
via the input system.
if NEW_LEDS
config LEDS_CLASS