flash/nor: add DesignWare SPI controller driver

Driver for DesignWare SPI controller, found on many SoCs (see compatible
list in Linux device tree bindings
Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml). This
implementation only supports MIPS as it was the only one available for the
tests, however, adding support for other architectures should require only
few adjustments. Driver relies on flash/nor/spi.h to find Flash chip info.
Driver internal functions support 24bit addressing mode, but due to
limitations of flash/nor/spi.h, it is not used. The reported writing speed
is about 60kb/s.
Lint, sanitizer and valgrind reported warnings were not related to the
driver.

Change-Id: Id3df5626ab88055f034f74f274823051dedefeb1
Signed-off-by: Sergey Matsievskiy <matsievskiysv@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8400
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

contrib/loaders/flash/dw-spi/Makefile

@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+TOOLCHAIN:=mipsel-linux-gnu-
+CC:=$(TOOLCHAIN)gcc
+OBJCOPY:=$(TOOLCHAIN)objcopy
+CFLAGS:=-O2 -Wall -Wextra -fpic -Wno-int-to-pointer-cast
+SRC=dw-spi.c
+OBJ=$(patsubst %.c, %.o,$(SRC))
+
+# sparx-iv
+ifeq ($(TOOLCHAIN),mipsel-linux-gnu-)
+	CFLAGS+= -march=24kec
+endif
+
+all: \
+	$(TOOLCHAIN)transaction.inc \
+	$(TOOLCHAIN)erase.inc \
+	$(TOOLCHAIN)check_fill.inc \
+	$(TOOLCHAIN)program.inc \
+	$(TOOLCHAIN)read.inc
+
+$(TOOLCHAIN)%.bin: $(OBJ)
+	$(OBJCOPY) --dump-section .$*=$@ $<
+
+%.inc: %.bin
+	xxd -i > $@ < $<
+
+.PHONY: clean
+clean:
+	rm -rf .ccls-cache
+	find . \( \
+	-iname "*.o" \
+	-o -iname "*.bin" \
+	-o -iname "*.inc" \
+	\) -delete