To alleviate the need to bitbang SWD, I've written a SWD SPI
implementation. This code is inspired by the work of luppy@appkaki.com
as shown at github.com/lupyuen/openocd-spi but with the desire to be
more generic. This implementation makes use of the more common 4 wire
SPI port using full duplex transfers to be able to capture the SWD ACK
bits when a SWD TX operation is in progress.
TEST:
Connects successfully with the following combinations:
Hosts:
Raspberry Pi 4B
Unnamed Qualcomm SoC with QUPv3 based SPI port
Targets:
Raspberry Pi 2040
Nordic nRF52840
NXP RT500
Change-Id: Ic2f38a1806085d527e6f999a3d15aea6f32d1019
Signed-off-by: Richard Pasek <rpasek@google.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8645
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-by: zapb <dev@zapb.de>
Tested-by: jenkins
83e0293f7b