spi: Add Socionext F_OSPI SPI flash controller driver

Introduce Socionext F_OSPI controller driver. This controller is used to
communicate with slave devices such as SPI Flash memories. It supports
4 slave devices and up to 8-bit wide bus, but supports master mode only.

This driver uses spi-mem framework for SPI flash memory access, and
can only operate indirect access mode and single data rate mode.
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Link: https://lore.kernel.org/r/20221124003351.7792-3-hayashi.kunihiko@socionext.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/Kconfig

@@ -906,6 +906,15 @@ config SPI_SLAVE_MT27XX
 	  say Y or M here.If you are not sure, say N.
 	  SPI slave drivers for Mediatek MT27XX series ARM SoCs.
 
+config SPI_SN_F_OSPI
+	tristate "Socionext F_OSPI SPI flash controller"
+	depends on OF && HAS_IOMEM
+	depends on SPI_MEM
+	help
+	  This enables support for the Socionext F_OSPI controller
+	  for connecting an SPI Flash memory over up to 8-bit wide bus.
+	  It supports indirect access mode only.
+
 config SPI_SPRD
 	tristate "Spreadtrum SPI controller"
 	depends on ARCH_SPRD || COMPILE_TEST

drivers/spi/Makefile

@@ -121,6 +121,7 @@ obj-$(CONFIG_SPI_SH_MSIOF)		+= spi-sh-msiof.o
 obj-$(CONFIG_SPI_SH_SCI)		+= spi-sh-sci.o
 obj-$(CONFIG_SPI_SIFIVE)		+= spi-sifive.o
 obj-$(CONFIG_SPI_SLAVE_MT27XX)          += spi-slave-mt27xx.o
+obj-$(CONFIG_SPI_SN_F_OSPI)		+= spi-sn-f-ospi.o
 obj-$(CONFIG_SPI_SPRD)			+= spi-sprd.o
 obj-$(CONFIG_SPI_SPRD_ADI)		+= spi-sprd-adi.o
 obj-$(CONFIG_SPI_STM32) 		+= spi-stm32.o