[ECOS] AT91 interrupt driven functionality

[harri dot siirtola at vtt dot fi]

1. I can't find any references to the tx & rx buffer pointers & char
counters (US_RPR, US_TPR, US_RCR, US_TCR), not even in the register address
definitions in plf_io.h. Shouldn't there be some in order to use buffered
I/O (or non-blocking transfers)?

2. start_xmit and stop_xmit exist, why not similar functions for rcv?

The reason I'm asking this: I'm losing rx chars coming from port 0 as
there's no hardware handshaking available on AT91R40807 (and xon/xoff is
somewhat undesirable in my application). If the system really uses buffers
of 128 bytes, this shouldn't be happening. So, what am I missing here?

Thanks,
	Harri