spi: spi-kspi2: Add KEBA SPI controller support

The KEBA SPI controller is found in the system FPGA of KEBA PLC devices.
It is used to connect the SPI flash chip of the FPGA and some SPI
devices.

It is a simple SPI controller with configurable speed. The hardware
supports only single byte transfers. There are no FIFOs or interrupts.

Signed-off-by: Gerhard Engleder <eg@keba.com>
Link: https://patch.msgid.link/20241202194003.57679-1-gerhard@engleder-embedded.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Gerhard Engleder

drivers/spi/Kconfig

@@ -542,6 +542,18 @@ config SPI_JCORE
 	  This enables support for the SPI master controller in the J-Core
 	  synthesizable, open source SoC.
 
+config SPI_KSPI2
+	tristate "Support for KEBA SPI master type 2 hardware"
+	depends on HAS_IOMEM
+	depends on KEBA_CP500 || COMPILE_TEST
+	select AUXILIARY_BUS
+	help
+	  This driver supports KEBA SPI master type 2 FPGA implementation,
+	  as found on CP500 devices for example.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called spi-kspi2.
+
 config SPI_LM70_LLP
 	tristate "Parallel port adapter for LM70 eval board (DEVELOPMENT)"
 	depends on PARPORT

drivers/spi/Makefile

@@ -74,6 +74,7 @@ obj-$(CONFIG_SPI_INTEL_PCI)		+= spi-intel-pci.o
 obj-$(CONFIG_SPI_INTEL_PLATFORM)	+= spi-intel-platform.o
 obj-$(CONFIG_SPI_LANTIQ_SSC)		+= spi-lantiq-ssc.o
 obj-$(CONFIG_SPI_JCORE)			+= spi-jcore.o
+obj-$(CONFIG_SPI_KSPI2)			+= spi-kspi2.o
 obj-$(CONFIG_SPI_LJCA)			+= spi-ljca.o
 obj-$(CONFIG_SPI_LM70_LLP)		+= spi-lm70llp.o
 obj-$(CONFIG_SPI_LOONGSON_CORE)		+= spi-loongson-core.o