swj-dp.tcl (SWD infrastructure #1)

Provide new helper proc that can set up either an SWD or JTAG DAP
based on the transport which is in use -- mostly for SWJ-DP.

 Also update some SWJ-DP based chips/targets to use it.  The goal
is making SWD-vs-JTAG transparent in most places.  SWJ-DP based chips
really need this flexible configuration to cope with debug adapters
that support different transports, without needing new target configs
for each transport or adapter.

For JTAG-DP, callers will use "jtag newtap" directly, as today; only
one chip-level transport option exists.

For SW-DP (e.g. LPC1[13]xx or EFM32, they'll use "swd newdap" directly
(part of an upcoming SWD transport patch).  Again, only one transport
option exists, so hard-wiring is appropriate there.

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

tcl/target/stellaris.cfg

@@ -1,5 +1,12 @@
 # TI/Luminary Stellaris LM3S chip family
 
+# Luminary chips support both JTAG and SWD transports.
+# Adapt based on what transport is active.
+source [find target/swj-dp.tcl]
+
+# For now we ignore the SPI and UART options, which
+# are usable only for ISP style initial flash programming.
+
 if { [info exists CHIPNAME] } {
    set  _CHIPNAME $CHIPNAME
 } else {
@@ -18,6 +25,12 @@ if { [info exists CPUTAPID ] } {
    set _CPUTAPID 0x0ba00477
 }
 
+# SWD DAP, and JTAG TAP, take same params for now;
+# ... even though SWD ignores all except TAPID, and
+# JTAG shouldn't need anything more then irlen. (and TAPID).
+swj_newdap $_CHIPNAME cpu -irlen 4 -irmask 0xf \
+ 	-expected-id $_CPUTAPID -ignore-version
+
 if { [info exists WORKAREASIZE ] } {
    set _WORKAREASIZE $WORKAREASIZE
 } else {