[9fans] first steps with the jtag...

[Gorka Guardiola <paurea@gmail.com>]

As there seemed to be a lot of interest here on the jtag front,
I´ll report my progress to this moment.

I added some minimal endpoint initialization support to
usb/serial (patch now on sources). I have written a
small tap state machine mover and mpsse assembler that now
seem to work. I have written some code to do mainly
three things:

1) reset the machine by asserting the trst signal through the jtag
This now works, so if anyone needs a remote usb  resetter, I have one :-).
The nice thing about this is that it is hw, it is equivalent of
pressing the button,
so if the machine is really frozen, it should still work.

2) initialize the mpsse. There is no visible outcome of this, so I don't know
if it works though the fact that 1) works may imply that it does.

3) shift either the IR or the DR. This does not work yet, I am unsure why
and I am debugging it now.

If you want to take a look at the unfinished thing as it is now, it is in
contrib/paurea/jtag.tgz. As I said, it is unfinished, so if it burns down
your plug, it is your fault...

Once 3 is there, most of the jtag support is done and the next step is
embedded ice.

G.