tcl: Add support for the Numato Lab Mimas A7 board

The Mimas A7 FPGA board has FTDI FT2232 whose channel B is connected to
Artix-7 FPGA's JTAG interface. Hence, OpenOCD can easily interface with
it via the its ftdi driver interface. Tested to be working great up to
30 MHz.

Change-Id: Ieda015fbc6135bf95ad5a069cbf38650da45911e
Signed-off-by: Rohit Singh <rohit91.2008@gmail.com>
Reviewed-on: http://openocd.zylin.com/4720
Tested-by: jenkins
Reviewed-by: Tim "mithro" Ansell <me@mith.ro>
Reviewed-by: Robert Jordens <jordens@gmail.com>
Reviewed-by: Paul Fertser <fercerpav@gmail.com>

tcl/board/numato_mimas_a7.cfg

@@ -0,0 +1,36 @@
+#
+# Numato Mimas A7 - Artix 7 FPGA Board
+#
+# https://numato.com/product/mimas-a7-artix-7-fpga-development-board-with-ddr-sdram-and-gigabit-ethernet
+#
+# Note: Connect external DC power supply if programming a heavy design onto FPGA.
+#       Programming while powering via USB may lead to programming failure.
+#       Therefore, prefer external power supply.
+
+interface ftdi
+ftdi_device_desc "Mimas Artix 7 FPGA Module"
+ftdi_vid_pid 0x2a19 0x1009
+
+# channel 0 is for custom purpose by users (like uart, fifo etc)
+# channel 1 is reserved for JTAG (by-default) or SPI (possible via changing solder jumpers)
+ftdi_channel 1
+ftdi_tdo_sample_edge falling
+
+
+# FTDI Pin Layout
+#
+# +--------+-------+-------+-------+-------+-------+-------+-------+
+# | DBUS7  | DBUS6 | DBUS5 | DBUS4 | DBUS3 | DBUS2 | DBUS1 | DBUS0 |
+# +--------+-------+-------+-------+-------+-------+-------+-------+
+# | PROG_B | OE_N  |  NC   |  NC   |  TMS  |  TDO  |  TDI  |  TCK  |
+# +--------+-------+-------+-------+-------+-------+-------+-------+
+#
+# OE_N is JTAG buffer output enable signal (active-low)
+# PROG_B is not used, so left as input to FTDI.
+#
+ftdi_layout_init 0x0008 0x004b
+reset_config none
+adapter_khz 30000
+
+source [find cpld/xilinx-xc7.cfg]
+source [find cpld/jtagspi.cfg]