spi: rockchip-sfc: add rockchip serial flash controller

Add the rockchip serial flash controller (SFC) driver.
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Signed-off-by: Jon Lin <jon.lin@rock-chips.com>
Tested-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Chris Morgan <macromorgan@hotmail.com>
Link: https://lore.kernel.org/r/20210812134546.31340-3-jon.lin@rock-chips.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/Kconfig

@@ -658,6 +658,18 @@ config SPI_ROCKCHIP
 	  The main usecase of this controller is to use spi flash as boot
 	  device.
 
+config SPI_ROCKCHIP_SFC
+	tristate "Rockchip Serial Flash Controller (SFC)"
+	depends on ARCH_ROCKCHIP || COMPILE_TEST
+	depends on HAS_IOMEM && HAS_DMA
+	help
+	  This enables support for Rockchip serial flash controller. This
+	  is a specialized controller used to access SPI flash on some
+	  Rockchip SOCs.
+
+	  ROCKCHIP SFC supports DMA and PIO modes. When DMA is not available,
+	  the driver automatically falls back to PIO mode.
+
 config SPI_RB4XX
 	tristate "Mikrotik RB4XX SPI master"
 	depends on SPI_MASTER && ATH79

drivers/spi/Makefile

@@ -95,6 +95,7 @@ obj-$(CONFIG_SPI_QCOM_GENI)		+= spi-geni-qcom.o
 obj-$(CONFIG_SPI_QCOM_QSPI)		+= spi-qcom-qspi.o
 obj-$(CONFIG_SPI_QUP)			+= spi-qup.o
 obj-$(CONFIG_SPI_ROCKCHIP)		+= spi-rockchip.o
+obj-$(CONFIG_SPI_ROCKCHIP_SFC)		+= spi-rockchip-sfc.o
 obj-$(CONFIG_SPI_RB4XX)			+= spi-rb4xx.o
 obj-$(CONFIG_MACH_REALTEK_RTL)		+= spi-realtek-rtl.o
 obj-$(CONFIG_SPI_RPCIF)			+= spi-rpc-if.o