[UrJTAG-dev] Add support for a DMA-only EJTAG bus implementation

[OB <obc...@gm...>]

Hello,

This is the 3rd and last patch for the support of the "neufbox4", a platform
using the BCM6358 chipset from broadcom.

This chip cannot use the Pracc method: I couldn't ever make it work, and
apparently this is common for these chipset (maybe we just don't know how).

However, as seen in hairydairymaid, it works in DMA mode.
There is a patch that currently exists but only for initialization, not for all
access (read/write/flash/erase) which still used Pracc for theses functions.

So I rewrite one called ejtag_dma.c , it seems cleaner for me, inspired from
both hairydairymaid & the current ejtag.c.

If you mind, I would accept any comments on this implementation, knowing that
it's the first time I code for UrJtag, I might have missed some concepts either
in urjtag or within the flash system itself.

With this patch & the 2 other small ones I posted, I was able to erase &
reflash my neufbox4 through jtag only, using a Amontec JTagKey and the
following config file :

~ > cat ~/.jtag/rc
 cable JTAGkey
 #frequency 500000 # Support 6MHz after all
 detect
 endian big
 initbus ejtag_dma
 detectflash 0x1E000000

(yes the flash is in 0x1E000000 - weird)

There is a page for this box : http://www.neufbox4.org ,
with a wiki including a JTAG description (I'm working on it).

Oh, last note : this code is , of course, under the same license as UrJTAG.

Thanks !

Julien
-- 
People in the embedded space don't do prototypes. They hack something until it
works, then it's done.