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- ==============
- 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.
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