ftdi swd: disable SWD output pin during input

* Disables the data output pin while SWD is reading, so that a simple FTDI
   SWD interface can be made by connecting TCK to SWD_CLK and TDI+TDO directly
   to SWDIO. Enabled by setting SWDIO_OE to 0.

Change-Id: I7d3b71cf3f4eea163cb320aff69ed95d219190bd
Signed-off-by: Patrick Stewart <patstew@gmail.com>
Signed-off-by: Roger Lendenmann <roger.lendenmann@intel.com>
Reviewed-on: http://openocd.zylin.com/2274
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Tested-by: jenkins

src/jtag/drivers/ftdi.c

@@ -1064,8 +1064,19 @@ static int ftdi_swd_init(void)
 static void ftdi_swd_swdio_en(bool enable)
 {
 	struct signal *oe = find_signal_by_name("SWDIO_OE");
-	if (oe)
-		ftdi_set_signal(oe, enable ? '1' : '0');
+	if (oe) {
+		if (oe->data_mask)
+			ftdi_set_signal(oe, enable ? '1' : '0');
+		else {
+			/* Sets TDI/DO pin (pin 2) to input during rx when both pins are connected
+			   to SWDIO */
+			if (enable)
+				direction |= jtag_direction_init & 0x0002U;
+			else
+				direction &= ~0x0002U;
+			mpsse_set_data_bits_low_byte(mpsse_ctx, output & 0xff, direction & 0xff);
+		}
+	}
 }
 
 /**

tcl/board/nordic_nrf52_ftx232.cfg

@@ -0,0 +1,11 @@
+#
+# nordic module NRF52 (nRF52832/52840) attached to an adafruit ft232h module
+# or any FT232H/FT2232H/FT4232H based board/module
+#
+
+source [find interface/ftdi/ft232h-module-swd.cfg]
+#source [find interface/ftdi/minimodule-swd.cfg]
+
+transport select swd
+
+source [find target/nrf52.cfg]

tcl/interface/ftdi/ft232h-module-swd.cfg

@@ -0,0 +1,52 @@
+#
+# ADAFRUIT FTDI FT232H as a SWD direct connect interface
+# Any FT232H based board may work
+#
+# http://www.ftdichip.com/Products/ICs/FT232H.htm
+#
+#
+
+interface ftdi
+
+ftdi_vid_pid 0x0403 0x6014
+
+# data MSB..LSB       direction (1:out) MSB..LSB
+# 0000'0000'0011'0000 0000'0000'0011'1011
+ftdi_layout_init 0x0030 0x003b
+# 0xfff8 0xfffb
+# Those signal are only required on some platforms or may required to be
+# enabled explicitely (e.g. nrf5x chips).
+ftdi_layout_signal nSRST -data 0x0010 -oe 0x0010
+ftdi_layout_signal nTRST -data 0x0020 -oe 0x0020
+
+# swd enable
+ftdi_layout_signal SWD_EN -data 0
+# tri-state (configure as input) TDO/TIO when reading
+ftdi_layout_signal SWDIO_OE -data 0
+
+transport select swd
+
+# re-configure TDO as tri-state
+#ftdi_layout_signal TDO -data 0x0002 -oe 0x0002
+#ftdi_layout_signal TDI -data 0x0004
+
+# Adafruit      FT232H    JTAG       SWD
+# Name  Pin     Name      Func       Func
+#  D0   J1-3    ADBUS0    TCK        SWDCLK
+#  D1   J1-4    ADBUS1    TDO/DI     SWDIO
+#  D2   J1-5    ADBUS2    TDI/DO     SWDIO
+#  D3   J1-6    ADBUS3    TMS        N/A
+#  D4   J1-7    ADBUS4    (GPIOL0)   /nSRST  optional module reset
+#  D5   J1-8    ADBUS5    (GPIOL1)   /nTRST  optional target reset
+#  D6   J1-9    ADBUS6    (GPIOL2)
+#  D7   J1-10   ADBUS7    (GPIOL3)
+#  C0   J2-1    ACBUS0    (GPIOH0)
+#  C1   J2-2    ACBUS1    (GPIOH1)
+#  C2   J2-3    ACBUS2    (GPIOH2)
+#  C3   J2-4    ACBUS3    (GPIOH3)
+#  C4   J2-5    ACBUS4    (GPIOH4)
+#  C5   J2-6    ACBUS5    (GPIOH5)
+#  C6   J2-7    ACBUS6    (GPIOH6)
+#  C7   J2-8    ACBUS7    (GPIOH7)
+#  C8   J2-9    ACBUS8
+#  C9   J2-10   ACBUS9

tcl/interface/ftdi/minimodule-swd.cfg

@@ -0,0 +1,54 @@
+#
+Supports SWD using the FT2232H or FT4232H minimodule.
+# Each can support 2 SWD interfaces.
+#
+# FT2232H or FT4232H minimodule channel 0 (Channel A)
+# Connector  FTDI              Target
+# Pin        Name
+# ---------  ------            ------
+# CN2-11     VIO               VDD_IO (Or connect to CN2-5 on the minimodule instead for a 3V3 interface)
+# CN2-2      GND               GND
+# CN2-7      ADBUS0 (TCK)      SWCLK
+# CN2-9      ADBUS2 (TDI/TDO)  SWDIO
+# CN2-10     ADBUS1 (TDO/TDI)  SWDIO
+# CN2-14     ADBUS4 (GPIOL0)   nRESET
+#
+# FT2232H minimodule channel 1 (Channel B)
+# FTDI       Target
+# ----       ------
+# CN2-11  -  VDD_IO
+# CN2-2   -  GND
+# CN3-26  -  SWCLK
+# CN3-25  -  SWDIO
+# CN3-24  -  SWDIO
+# CN3-21  -  nRESET
+#
+# FT4232H minimodule channel 1 (Channel B)
+# FTDI       Target
+# ----       ------
+# CN2-11  -  VDD_IO
+# CN2-2   -  GND
+# CN2-18  -  SWCLK
+# CN2-17  -  SWDIO
+# CN2-20  -  SWDIO
+# CN2-22  -  nRESET
+#
+
+interface ftdi
+
+#Select your module type and channel
+
+#ftdi_device_desc "FT2232H MiniModule"
+ftdi_vid_pid 0x0403 0x6010
+#ftdi_channel 1
+
+#ftdi_device_desc "FT4232H MiniModule"
+#ftdi_vid_pid 0x0403 0x6011
+#ftdi_channel 1
+
+ftdi_layout_init 0x0000 0x000b
+ftdi_layout_signal nSRST -data 0x0010 -oe 0x0010
+ftdi_layout_signal SWD_EN -data 0
+ftdi_layout_signal SWDIO_OE -data 0
+
+transport select swd