Each USB device has an emulator. Currently this can only be found by
supplying the 'pipe' value, which contains the device number. Add a way
to find it directly from the emulated device.
Signed-off-by: Simon Glass <sjg@chromium.org>
With sandbox we want to be able to emulate USB devices so that we can test
the USB stack. Add a uclass to support this. It implements the same
operations as a normal USB device driver, but in this case passes them on
to an emulation driver.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Marek Vasut <marex@denx.de>
