riscv-openocd/tcl/target/pxa255.cfg

# PXA255 chip ... originally from Intel, PXA line was sold to Marvell.
#  This chip is now at end-of-life.  Final orders have been taken.

if { [info exists CHIPNAME] } {
   set  _CHIPNAME $CHIPNAME
} else {
   set  _CHIPNAME pxa255
}

if { [info exists ENDIAN] } {
   set  _ENDIAN $ENDIAN
} else {
   set  _ENDIAN little
}

if { [info exists CPUTAPID ] } {
   set _CPUTAPID $CPUTAPID
} else {
   set _CPUTAPID 0x69264013
}

jtag newtap $_CHIPNAME cpu -irlen 5 -expected-id $_CPUTAPID

set _TARGETNAME $_CHIPNAME.cpu
target create $_TARGETNAME xscale -endian $_ENDIAN \
	-chain-position $_CHIPNAME.cpu

# PXA255 comes out of reset using 3.6864 MHz oscillator.
# Until the PLL kicks in, keep the JTAG clock slow enough
# that we get no errors.
jtag_khz 300
$_TARGETNAME configure -event "reset-start" { jtag_khz 300 }

# both TRST and SRST are *required* for debug
# DCSR is often accessed with SRST active
reset_config trst_and_srst separate srst_nogate

# reset processing that works with PXA
proc init_reset {mode} {
	# assert both resets; equivalent to power-on reset
	jtag_reset 1 1

	# drop TRST after at least 32 cycles
	sleep 1
	jtag_reset 0 1

	# minimum 32 TCK cycles to wake up the controller
	runtest 50

	# now the TAP will be responsive; validate scanchain
	jtag arp_init

	# ... and take it out of reset
	jtag_reset 0 0
}

proc jtag_init {} {
	init_reset startup
}