device-tree-bindings/spi/soft-spi.txt

3 The soft SPI bus implementation allows the use of GPIO pins to simulate a
4 SPI bus. No SPI host is required for this to work. The down-side is that the
9 compatible: "u-boot,soft-spi"
10 soft_spi_cs: GPIO number to use for SPI chip select (output)
11 soft_spi_sclk: GPIO number to use for SPI clock (output)
12 soft_spi_mosi: GPIO number to use for SPI MOSI line (output)
13 soft_spi_miso GPIO number to use for SPI MISO line (input)
14 spi-delay-us: Number of microseconds of delay between each CS transition
16 The GPIOs should be specified as required by the GPIO controller referenced.
18 typically holds the GPIO number.
23 	soft-spi {
24 		compatible = "u-boot,soft-spi";
25 		cs-gpio = <&gpio 235 0>;	/* Y43 */
26 		sclk-gpio = <&gpio 225 0>;	/* Y31 */
27 		mosi-gpio = <&gpio 227 0>;	/* Y33 */
28 		miso-gpio = <&gpio 224 0>;	/* Y30 */
29 		spi-delay-us = <1>;
30 		#address-cells = <1>;
31 		#size-cells = <0>;