Syncronous Interrupt Transfer

[Chris Telting]

Just learning the USB API.

Can someone point me to a driver to use as an example of a synchronous 
call?  Do
I need to use a mutex?

I have a device that that does the equivalent of control transfers over 
an interrupt pipe.
So I need to send data, get status, send more data, get status again, 
and then finally start
retrieving data; all using interrupt transfers.  Been going over the 
drivers in the kernel
and they are all looking to be doing async or synchronous back through 
user mode.