u-boot/drivers/spi/Kconfig

config DM_SPI
	bool "Enable Driver Model for SPI drivers"
	depends on DM
	help
	  Enable driver model for SPI. The SPI slave interface
	  (spi_setup_slave(), spi_xfer(), etc.) is then implemented by
	  the SPI uclass. Drivers provide methods to access the SPI
	  buses that they control. The uclass interface is defined in
	  include/spi.h. The existing spi_slave structure is attached
	  as 'parent data' to every slave on each bus. Slaves
	  typically use driver-private data instead of extending the
	  spi_slave structure.

config SANDBOX_SPI
	bool "Sandbox SPI driver"
	depends on SANDBOX && DM
	help
	  Enable SPI support for sandbox. This is an emulation of a real SPI
	  bus. Devices can be attached to the bus using the device tree
	  which specifies the driver to use. As an example, see this device
	  tree fragment from sandbox.dts. It shows that the SPI bus has a
	  single flash device on chip select 0 which is emulated by the driver
	  for "sandbox,spi-flash", which is in drivers/mtd/spi/sandbox.c.

	  spi@0 {
		#address-cells = <1>;
		#size-cells = <0>;
		reg = <0>;
		compatible = "sandbox,spi";
		cs-gpios = <0>, <&gpio_a 0>;
		flash@0 {
			reg = <0>;
			compatible = "spansion,m25p16", "sandbox,spi-flash";
			spi-max-frequency = <40000000>;
			sandbox,filename = "spi.bin";
		};
	};

config DESIGNWARE_SPI
	bool "Designware SPI driver"
	depends on DM_SPI
	help
	  Enable the Designware SPI driver. This driver can be used to
	  access the SPI NOR flash on platforms embedding this Designware
	  IP core.

config CADENCE_QSPI
	bool "Cadence QSPI driver"
	depends on DM_SPI
	help
	  Enable the Cadence Quad-SPI (QSPI) driver. This driver can be
	  used to access the SPI NOR flash on platforms embedding this
	  Cadence IP core.