37 строки
1.2 KiB
Plaintext
37 строки
1.2 KiB
Plaintext
|
Userspace LEDs
|
||
|
|
==============
|
||
|
|
|
||
|
|
The uleds driver supports userspace LEDs. This can be useful for testing
|
||
|
|
triggers and can also be used to implement virtual LEDs.
|
||
|
|
|
||
|
|
|
||
|
|
Usage
|
||
|
|
=====
|
||
|
|
|
||
|
|
When the driver is loaded, a character device is created at /dev/uleds. To
|
||
|
|
create a new LED class device, open /dev/uleds and write a uleds_user_dev
|
||
|
|
structure to it (found in kernel public header file linux/uleds.h).
|
||
|
|
|
||
|
|
#define LED_MAX_NAME_SIZE 64
|
||
|
|
|
||
|
|
struct uleds_user_dev {
|
||
|
|
char name[LED_MAX_NAME_SIZE];
|
||
|
|
};
|
||
|
|
|
||
|
|
A new LED class device will be created with the name given. The name can be
|
||
|
|
any valid sysfs device node name, but consider using the LED class naming
|
||
|
|
convention of "devicename:color:function".
|
||
|
|
|
||
|
|
The current brightness is found by reading a single byte from the character
|
||
|
|
device. Values are unsigned: 0 to 255. Reading will block until the brightness
|
||
|
|
changes. The device node can also be polled to notify when the brightness value
|
||
|
|
changes.
|
||
|
|
|
||
|
|
The LED class device will be removed when the open file handle to /dev/uleds
|
||
|
|
is closed.
|
||
|
|
|
||
|
|
Multiple LED class devices are created by opening additional file handles to
|
||
|
|
/dev/uleds.
|
||
|
|
|
||
|
|
See tools/leds/uledmon.c for an example userspace program.
|