1SPI (Serial Peripheral Interface) busses 2 3SPI busses can be described with a node for the SPI master device 4and a set of child nodes for each SPI slave on the bus. For this 5discussion, it is assumed that the system's SPI controller is in 6SPI master mode. This binding does not describe SPI controllers 7in slave mode. 8 9The SPI master node requires the following properties: 10- #address-cells - number of cells required to define a chip select 11 address on the SPI bus. 12- #size-cells - should be zero. 13- compatible - name of SPI bus controller following generic names 14 recommended practice. 15No other properties are required in the SPI bus node. It is assumed 16that a driver for an SPI bus device will understand that it is an SPI bus. 17However, the binding does not attempt to define the specific method for 18assigning chip select numbers. Since SPI chip select configuration is 19flexible and non-standardized, it is left out of this binding with the 20assumption that board specific platform code will be used to manage 21chip selects. Individual drivers can define additional properties to 22support describing the chip select layout. 23 24SPI slave nodes must be children of the SPI master node and can 25contain the following properties. 26- reg - (required) chip select address of device. 27- compatible - (required) name of SPI device following generic names 28 recommended practice 29- spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz 30- spi-cpol - (optional) Empty property indicating device requires 31 inverse clock polarity (CPOL) mode 32- spi-cpha - (optional) Empty property indicating device requires 33 shifted clock phase (CPHA) mode 34- spi-cs-high - (optional) Empty property indicating device requires 35 chip select active high 36 37SPI example for an MPC5200 SPI bus: 38 spi@f00 { 39 #address-cells = <1>; 40 #size-cells = <0>; 41 compatible = "fsl,mpc5200b-spi","fsl,mpc5200-spi"; 42 reg = <0xf00 0x20>; 43 interrupts = <2 13 0 2 14 0>; 44 interrupt-parent = <&mpc5200_pic>; 45 46 ethernet-switch@0 { 47 compatible = "micrel,ks8995m"; 48 spi-max-frequency = <1000000>; 49 reg = <0>; 50 }; 51 52 codec@1 { 53 compatible = "ti,tlv320aic26"; 54 spi-max-frequency = <100000>; 55 reg = <1>; 56 }; 57 }; 58