0001 ==============
0002 Userspace LEDs
0003 ==============
0004
0005 The uleds driver supports userspace LEDs. This can be useful for testing
0006 triggers and can also be used to implement virtual LEDs.
0007
0008
0009 Usage
0010 =====
0011
0012 When the driver is loaded, a character device is created at /dev/uleds. To
0013 create a new LED class device, open /dev/uleds and write a uleds_user_dev
0014 structure to it (found in kernel public header file linux/uleds.h)::
0015
0016 #define LED_MAX_NAME_SIZE 64
0017
0018 struct uleds_user_dev {
0019 char name[LED_MAX_NAME_SIZE];
0020 };
0021
0022 A new LED class device will be created with the name given. The name can be
0023 any valid sysfs device node name, but consider using the LED class naming
0024 convention of "devicename:color:function".
0025
0026 The current brightness is found by reading a single byte from the character
0027 device. Values are unsigned: 0 to 255. Reading will block until the brightness
0028 changes. The device node can also be polled to notify when the brightness value
0029 changes.
0030
0031 The LED class device will be removed when the open file handle to /dev/uleds
0032 is closed.
0033
0034 Multiple LED class devices are created by opening additional file handles to
0035 /dev/uleds.
0036
0037 See tools/leds/uledmon.c for an example userspace program.
