xref: /freebsd/sys/contrib/device-tree/Bindings/spi/spi-controller.yaml (revision b197d4b893974c9eb4d7b38704c6d5c486235d6f) 
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 Generic Binding
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  $nodename:
20    pattern: "^spi(@.*|-[0-9a-f])*$"
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
98    required:
99      - compatible
100      - reg
101
102allOf:
103  - if:
104      not:
105        required:
106          - spi-slave
107    then:
108      properties:
109        "#address-cells":
110          const: 1
111    else:
112      properties:
113        "#address-cells":
114          const: 0
115
116additionalProperties: true
117
118examples:
119  - |
120    spi@80010000 {
121        #address-cells = <1>;
122        #size-cells = <0>;
123        compatible = "fsl,imx28-spi";
124        reg = <0x80010000 0x2000>;
125        interrupts = <96>;
126        dmas = <&dma_apbh 0>;
127        dma-names = "rx-tx";
128
129        display@0 {
130            compatible = "lg,lg4573";
131            spi-max-frequency = <1000000>;
132            reg = <0>;
133        };
134
135        sensor@1 {
136            compatible = "bosch,bme680";
137            spi-max-frequency = <100000>;
138            reg = <1>;
139        };
140
141        flash@2 {
142          compatible = "jedec,spi-nor";
143          spi-max-frequency = <50000000>;
144          reg = <2>, <3>;
145          stacked-memories = /bits/ 64 <0x10000000 0x10000000>;
146        };
147    };
148