[coreboot] USB POST card

Peter Stuge peter at stuge.se
Mon Sep 21 20:26:34 CEST 2009

Stefan Reinauer wrote:
> > The only USB option is a Debug Class device.
> Or the Artec LPC dongle - 

Sorry, I meant for USB connection to system being debugged. :)

> it can transport POST codes via usb-serial from the target... For
> someone with VHDL knowledge it might be possible to add a "fake
> serial port" to the dongle.

The way to get data out that I like the best is to use
reads-mean-write, where a sequence of reading from certain addresses
sends the lowest byte of the last read address via USB to the host
and the user.

Unfortunately, the dongle is already a serial device so it is
difficult to create another serial port. That would be done using a
kernel line discipline.

Ideally, the USB descriptors and USB firmware in the dongle could be
changed instead, which would allow for more channels besides the
current communication.

But I don't think it's doable with the FTDI USB chips, they are much
too simple.

It would of course be possible to use the existing USB-serial
channel, just that the dongle would need to be reset before the next
reprogram, once it has entered the reads-mean-write mode. That might
be OK.


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