tcl/target/at91sama5d2.cfg: allow choice of SWD instead of JTAG

The target supports both SWD and JTAG, but the existing cfg file
only supports JTAG.  Using the standard [using_jtag] mechanism,
the user would now have a choice.

Change-Id: Ic6adb68090422812d591f6bf5b945ac10f323c74
Signed-off-by: Peter Lawrence <majbthrd@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8020
Reviewed-by: Jörg Wunsch <openocd@uriah.heep.sax.de>
Reviewed-by: Paul Fertser <fercerpav@gmail.com>
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

tcl/target/at91sama5d2.cfg

@@ -1,5 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 #
+# SAMA5D2 devices support both JTAG and SWD transports.
+#
 # The JTAG connection is disabled at reset, and during the ROM Code execution.
 # It is re-enabled when the ROM code jumps in the boot file copied from an
 # external Flash memory into the internalSRAM, or when the ROM code launches
@@ -12,14 +14,28 @@
 # - if enabled, boundary Scan mode is activated. JTAG ID Code value is 0x05B3F03F.
 # - if disabled, ICE mode is activated. Debug Port JTAG IDCODE value is 0x5BA00477
 #
+
+source [find target/swj-dp.tcl]
+
+#jtag scan chain
+if { [info exists CPUTAPID] } {
+	set _CPUTAPID $CPUTAPID
+} else {
+	if { [using_jtag] } {
+		set _CPUTAPID 0x5ba00477
+	} else {
+		# SWD IDCODE (single drop, arm)
+		set _CPUTAPID 0x5ba02477
+	}
+}
+
 if { [info exists CHIPNAME] } {
 	set  _CHIPNAME $CHIPNAME
 } else {
 	set  _CHIPNAME at91sama5d2
 }
 
-jtag newtap $_CHIPNAME cpu -irlen 4 -ircapture 0x01 -irmask 0x0f \
-	-expected-id 0x5ba00477
+swj_newdap $_CHIPNAME cpu -irlen 4 -ircapture 0x1 -irmask 0xf -expected-id $_CPUTAPID
 
 # Cortex-A5 target
 set _TARGETNAME $_CHIPNAME.cpu_a5