FreeBSD: Asynchronous USB read in usermode

[Martin Poupe]

Hello,
I am porting linux application which does both synchronous and 
asynchronously read from USB device.
Synchronous transfer is not a problem - libusb was used and it is 
working fine on FreeBSD too. Problem is the asynchronous reading, I 
cannot find any kernel call similar
to linux submit urb. I tried the aio_read() but it seems it is not 
supported on file which is actually USB device.
Function usbd_bulk_transfer() (usbdi_util.h) seems interesting, but I am 
afraid it is only for kernel usage.
Is there some method how to read from the USB device asynchronously in 
usermode ?

Thanks,
Martin