From: David Brownell <dbrownell@users.sourceforge.net>
Date: Mon, 26 Oct 2009 07:36:03 +0000 (-0700)
Subject: JTAG: simple autoprobing
X-Git-Tag: v0.3.0-rc0~26
X-Git-Url: https://review.openocd.org/gitweb?p=openocd.git;a=commitdiff_plain;h=6cb1d10cdad509939e3decf089e08c289d85d5cf;hp=6cb1d10cdad509939e3decf089e08c289d85d5cf

JTAG: simple autoprobing

This patch adds basic autoprobing support for the JTAG scan chains
which cooperate.  To use, you can invoke OpenOCD with just:

 - interface spec: "-f interface/...cfg"
 - possibly with "-c 'reset_config ...'" for SRST/TRST
 - possibly with "-c 'jtag_khz ...'" for the JTAG clock

Then set up config files matching the reported TAPs.  It doesn't
declare targets ... just TAPs.  So facilities above the JTAG and
SVF/XSVF levels won't be available without a real config; this is
almost purely a way to generate diagnostics.

Autoprobe was successful with most boards I tested, except ones
incorporating C55x DSPs (which don't cooperate with this scheme
for IR length autodetection).  Here's what one multi-TAP chip
reported, with the "Warn:" prefixes removed:

 clock speed 500 kHz
 There are no enabled taps.  AUTO PROBING MIGHT NOT WORK!!
 AUTO auto0.tap - use "jtag newtap auto0 tap -expected-id 0x2b900f0f ..."
 AUTO auto1.tap - use "jtag newtap auto1 tap -expected-id 0x07926001 ..."
 AUTO auto2.tap - use "jtag newtap auto2 tap -expected-id 0x0b73b02f ..."
 AUTO auto0.tap - use "... -irlen 4"
 AUTO auto1.tap - use "... -irlen 4"
 AUTO auto2.tap - use "... -irlen 6"
 no gdb ports allocated as no target has been specified

The patch tweaks IR setup a bit, so we can represent TAPs with
undeclared IR length.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---