spi: airoha: add SPI-NAND Flash controller driver

Introduce support for SPI-NAND driver of the Airoha NAND Flash Interface
found on Airoha ARM SoCs.
Tested-by: Rajeev Kumar <Rajeev.Kumar@airoha.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/6c9db20505b01a66807995374f2af475a23ce5b2.1714377864.git.lorenzo@kernel.orgSigned-off-by: Mark Brown <broonie@kernel.org>

MAINTAINERS

@@ -653,6 +653,15 @@ S:	Supported
 F:	fs/aio.c
 F:	include/linux/*aio*.h
 
+AIROHA SPI SNFI DRIVER
+M:	Lorenzo Bianconi <lorenzo@kernel.org>
+M:	Ray Liu <ray.liu@airoha.com>
+L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
+L:	linux-spi@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/spi/airoha,en7581-snand.yaml
+F:	drivers/spi/spi-airoha.c
+
 AIRSPY MEDIA DRIVER
 L:	linux-media@vger.kernel.org
 S:	Orphan

drivers/spi/Kconfig

@@ -57,6 +57,16 @@ config SPI_MEM
 
 comment "SPI Master Controller Drivers"
 
+config SPI_AIROHA_SNFI
+	tristate "Airoha SPI NAND Flash Interface"
+	depends on ARCH_AIROHA || COMPILE_TEST
+	depends on SPI_MASTER
+	select REGMAP_MMIO
+	help
+	  This enables support for SPI-NAND mode on the Airoha NAND
+	  Flash Interface found on Airoha ARM SoCs. This controller
+	  is implemented as a SPI-MEM controller.
+
 config SPI_ALTERA
 	tristate "Altera SPI Controller platform driver"
 	select SPI_ALTERA_CORE

drivers/spi/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_SPI_SPIDEV)		+= spidev.o
 obj-$(CONFIG_SPI_LOOPBACK_TEST)		+= spi-loopback-test.o
 
 # SPI master controller drivers (bus)
+obj-$(CONFIG_SPI_AIROHA_SNFI)		+= spi-airoha-snfi.o
 obj-$(CONFIG_SPI_ALTERA)		+= spi-altera-platform.o
 obj-$(CONFIG_SPI_ALTERA_CORE)		+= spi-altera-core.o
 obj-$(CONFIG_SPI_ALTERA_DFL)		+= spi-altera-dfl.o