jtagspi/pld: add support from xilinx driver

Provide jtagspi with information to use jtagspi for
programming spi-flash devices on xilinx devices
using a proxy bitstream.

Change-Id: I68000d71de25118ed8a8603e544cff1dc69bd9ba
Signed-off-by: Daniel Anselmi <danselmi@gmx.ch>
Reviewed-on: https://review.openocd.org/c/openocd/+/7836
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

tcl/board/digilent_cmod_s7.cfg

@@ -0,0 +1,25 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+# digilent CMOD S7
+# https://digilent.com/reference/programmable-logic/cmod-s7/reference-manual
+
+
+adapter driver ftdi
+ftdi channel 0
+ftdi layout_init 0x0008 0x008b
+ftdi vid_pid 0x0403 0x6010
+reset_config none
+transport select jtag
+
+adapter speed 10000
+
+source [find cpld/xilinx-xc7.cfg]
+
+# "ipdbg -start -tap xc7.tap -hub 0x02 -tool 0 -port 5555"
+#openocd -f board/digilent_cmod_s7.cfg -c "init" -c "pld load xc7.pld shared_folder/cmod_s7_fast.bit"
+
+set JTAGSPI_CHAIN_ID xc7.pld
+source [find cpld/jtagspi.cfg]
+
+#jtagspi_init xc7.pld "shared_folder/bscan_spi_xc7s25.bit" 0xab
+#jtagspi_program shared_folder/cmod_s7_fast.bit 0