pipistrello: ftdi-jtag/spartan6/jtagspi board

The Pipistrello is a low cost FPGA board with a Xilinx
Spartan6 LX45, a SPI flash and onboard FTDI JTAG.
This board is a good example use case for the jtagspi
flash driver talking through a proxy bitstream.

Change-Id: I04a80610ff825c36ebcb67b879507028eed141ad
Signed-off-by: Robert Jordens <jordens@gmail.com>
Reviewed-on: http://openocd.zylin.com/2846
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

tcl/board/pipistrello.cfg

@@ -0,0 +1,14 @@
+# http://pipistrello.saanlima.com/
+
+source [find interface/ftdi/pipistrello.cfg]
+source [find cpld/xilinx-xc6s.cfg]
+source [find cpld/jtagspi.cfg]
+
+# example command to write bitstream, soft-cpu bios and runtime:
+# openocd -f board/pipistrello.cfg -c "init;\
+# jtagspi_init 0 bscan_spi_xc6slx45.bit;\
+# jtagspi_program bitstream-pistrello.bin 0;\
+# jtagspi_program bios.bin 0x170000;\
+# jtagspi_program runtime.fbi 0x180000;\
+# xc6s_program xc6s.tap;\
+# exit"

tcl/cpld/xilinx-xc6s.cfg

@@ -0,0 +1,54 @@
+# xilinx spartan6
+# http://www.xilinx.com/support/documentation/user_guides/ug380.pdf
+
+if { [info exists CHIPNAME] } {
+	set _CHIPNAME $CHIPNAME
+} else {
+	set _CHIPNAME xc6s
+}
+
+# the 4 top bits (28:31) are the die stepping. ignore it.
+jtag newtap $_CHIPNAME tap -irlen 6 -ignore-version \
+	-expected-id 0x04000093 \
+	-expected-id 0x04001093 \
+	-expected-id 0x04002093 \
+	-expected-id 0x04004093 \
+	-expected-id 0x04024093 \
+	-expected-id 0x04008093 \
+	-expected-id 0x04028093 \
+	-expected-id 0x0400E093 \
+	-expected-id 0x0402E093 \
+	-expected-id 0x04011093 \
+	-expected-id 0x04031093 \
+	-expected-id 0x0401D093 \
+	-expected-id 0x0403D093
+
+pld device virtex2 $_CHIPNAME.tap
+
+set XC6S_CFG_IN 0x05
+set XC6S_JSHUTDOWN 0x0d
+set XC6S_JPROGRAM 0x0b
+set XC6S_JSTART 0x0c
+set XC6S_BYPASS 0x3f
+
+proc xc6s_program {tap} {
+	global XC6S_JSHUTDOWN XC6S_JPROGRAM XC6S_JSTART XC6S_BYPASS
+	irscan $tap $XC6S_JSHUTDOWN
+	irscan $tap $XC6S_JPROGRAM
+	irscan $tap $XC6S_JSTART
+	irscan $tap $XC6S_BYPASS
+}
+
+#xtp038 and xc3sprog approach
+proc xc6s_program_iprog {tap} {
+	global XC6S_JSHUTDOWN XC6S_JSTART XC6S_BYPASS XC6S_CFG_IN
+	irscan $tap $XC6S_JSHUTDOWN
+	runtest 16
+	irscan $tap $XC6S_CFG_IN
+	# xtp038 IPROG 16bit flipped
+	drscan $tap 16 0xffff 16 0x9955 16 0x66aa 16 0x850c 16 0x7000 16 0x0004
+	irscan $tap $XC6S_JSTART
+	runtest 32
+	irscan $tap $XC6S_BYPASS
+	runtest 1
+}

tcl/interface/ftdi/pipistrello.cfg

@@ -0,0 +1,13 @@
+# http://pipistrello.saanlima.com/
+# http://www.saanlima.com/download/pipistrello-v2.0/pipistrello_v2_schematic.pdf
+interface ftdi
+ftdi_device_desc "Pipistrello LX45"
+ftdi_vid_pid 0x0403 0x6010
+# interface 1 is the uart
+ftdi_channel 0
+# just TCK TDI TDO TMS, no reset
+ftdi_layout_init 0x0008 0x000b
+reset_config none
+# this generally works fast: the fpga can handle 30MHz, the spi flash can handle
+# 54MHz with simple read, no dummy cycles, and wait-for-write-completion
+adapter_khz 30000