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 <email@example.com>