1# SPDX-License-Identifier: GPL-2.0 2%YAML 1.2 3--- 4$id: http://devicetree.org/schemas/spi/spi-controller.yaml# 5$schema: http://devicetree.org/meta-schemas/core.yaml# 6 7title: SPI Controller Common Properties 8 9maintainers: 10 - Mark Brown <broonie@kernel.org> 11 12description: | 13 SPI busses can be described with a node for the SPI controller device 14 and a set of child nodes for each SPI slave on the bus. The system SPI 15 controller may be described for use in SPI master mode or in SPI slave mode, 16 but not for both at the same time. 17 18properties: 19 $nodename: 20 pattern: "^spi(@.*|-([0-9]|[1-9][0-9]+))?$" 21 22 "#address-cells": 23 enum: [0, 1] 24 25 "#size-cells": 26 const: 0 27 28 cs-gpios: 29 description: | 30 GPIOs used as chip selects. 31 If that property is used, the number of chip selects will be 32 increased automatically with max(cs-gpios, hardware chip selects). 33 34 So if, for example, the controller has 4 CS lines, and the 35 cs-gpios looks like this 36 cs-gpios = <&gpio1 0 0>, <0>, <&gpio1 1 0>, <&gpio1 2 0>; 37 38 Then it should be configured so that num_chipselect = 4, with 39 the following mapping 40 cs0 : &gpio1 0 0 41 cs1 : native 42 cs2 : &gpio1 1 0 43 cs3 : &gpio1 2 0 44 45 The second flag of a gpio descriptor can be GPIO_ACTIVE_HIGH (0) 46 or GPIO_ACTIVE_LOW(1). Legacy device trees often use 0. 47 48 There is a special rule set for combining the second flag of an 49 cs-gpio with the optional spi-cs-high flag for SPI slaves. 50 51 Each table entry defines how the CS pin is to be physically 52 driven (not considering potential gpio inversions by pinmux): 53 54 device node | cs-gpio | CS pin state active | Note 55 ================+===============+=====================+===== 56 spi-cs-high | - | H | 57 - | - | L | 58 spi-cs-high | ACTIVE_HIGH | H | 59 - | ACTIVE_HIGH | L | 1 60 spi-cs-high | ACTIVE_LOW | H | 2 61 - | ACTIVE_LOW | L | 62 63 Notes: 64 1) Should print a warning about polarity inversion. 65 Here it would be wise to avoid and define the gpio as 66 ACTIVE_LOW. 67 2) Should print a warning about polarity inversion 68 because ACTIVE_LOW is overridden by spi-cs-high. 69 Should be generally avoided and be replaced by 70 spi-cs-high + ACTIVE_HIGH. 71 72 num-cs: 73 $ref: /schemas/types.yaml#/definitions/uint32 74 description: 75 Total number of chip selects. 76 77 spi-slave: 78 $ref: /schemas/types.yaml#/definitions/flag 79 description: 80 The SPI controller acts as a slave, instead of a master. 81 82 slave: 83 type: object 84 85 properties: 86 compatible: 87 description: 88 Compatible of the SPI device. 89 90 required: 91 - compatible 92 93patternProperties: 94 "^.*@[0-9a-f]+$": 95 type: object 96 $ref: spi-peripheral-props.yaml 97 additionalProperties: true 98 99 properties: 100 spi-3wire: 101 $ref: /schemas/types.yaml#/definitions/flag 102 description: 103 The device requires 3-wire mode. 104 105 spi-cpha: 106 $ref: /schemas/types.yaml#/definitions/flag 107 description: 108 The device requires shifted clock phase (CPHA) mode. 109 110 spi-cpol: 111 $ref: /schemas/types.yaml#/definitions/flag 112 description: 113 The device requires inverse clock polarity (CPOL) mode. 114 115 required: 116 - compatible 117 - reg 118 119allOf: 120 - if: 121 not: 122 required: 123 - spi-slave 124 then: 125 properties: 126 "#address-cells": 127 const: 1 128 else: 129 properties: 130 "#address-cells": 131 const: 0 132 133additionalProperties: true 134 135examples: 136 - | 137 spi@80010000 { 138 #address-cells = <1>; 139 #size-cells = <0>; 140 compatible = "fsl,imx28-spi"; 141 reg = <0x80010000 0x2000>; 142 interrupts = <96>; 143 dmas = <&dma_apbh 0>; 144 dma-names = "rx-tx"; 145 146 display@0 { 147 compatible = "lg,lg4573"; 148 spi-max-frequency = <1000000>; 149 reg = <0>; 150 }; 151 152 sensor@1 { 153 compatible = "bosch,bme680"; 154 spi-max-frequency = <100000>; 155 reg = <1>; 156 }; 157 158 flash@2 { 159 compatible = "jedec,spi-nor"; 160 spi-max-frequency = <50000000>; 161 reg = <2>, <3>; 162 stacked-memories = /bits/ 64 <0x10000000 0x10000000>; 163 }; 164 }; 165