xref: /freebsd/sys/contrib/device-tree/Bindings/i2c/i2c-mux-gpmux.yaml (revision f81cdf24ba5436367377f7c8e8f51f6df2a75ca7) 
1# SPDX-License-Identifier: GPL-2.0
2%YAML 1.2
3---
4$id: http://devicetree.org/schemas/i2c/i2c-mux-gpmux.yaml#
5$schema: http://devicetree.org/meta-schemas/core.yaml#
6
7title: General Purpose I2C Bus Mux
8
9maintainers:
10  - Peter Rosin <peda@axentia.se>
11
12description: |+
13  This binding describes an I2C bus multiplexer that uses a mux controller
14  from the mux subsystem to route the I2C signals.
15
16                                    .-----.  .-----.
17                                    | dev |  | dev |
18      .------------.                '-----'  '-----'
19      | SoC        |                   |        |
20      |            |          .--------+--------'
21      |   .------. |  .------+    child bus A, on MUX value set to 0
22      |   | I2C  |-|--| Mux  |
23      |   '------' |  '--+---+    child bus B, on MUX value set to 1
24      |   .------. |     |    '----------+--------+--------.
25      |   | MUX- | |     |               |        |        |
26      |   | Ctrl |-|-----+            .-----.  .-----.  .-----.
27      |   '------' |                  | dev |  | dev |  | dev |
28      '------------'                  '-----'  '-----'  '-----'
29
30
31allOf:
32  - $ref: /schemas/i2c/i2c-mux.yaml#
33
34properties:
35  compatible:
36    const: i2c-mux
37
38  i2c-parent:
39    $ref: /schemas/types.yaml#/definitions/phandle
40    description:
41      The phandle of the I2C bus that this multiplexer's master-side port is
42      connected to.
43
44  mux-controls:
45    maxItems: 1
46    description:
47      The mux-controller states are the I2C sub-bus numbers.
48
49  mux-locked:
50    type: boolean
51    description: |
52      Explicitly allow unrelated I2C transactions on the parent I2C adapter at
53      these times:
54       - during setup of the multiplexer
55       - between setup of the multiplexer and the child bus I2C transaction
56       - between the child bus I2C transaction and releasing of the multiplexer
57       - during releasing of the multiplexer
58
59      However, I2C transactions to devices behind all I2C multiplexers connected
60      to the same parent adapter that this multiplexer is connected to are blocked
61      for the full duration of the complete multiplexed I2C transaction (i.e.
62      including the times covered by the above list).
63      If mux-locked is not present, the multiplexer is assumed to be parent-locked.
64      This means that no unrelated I2C transactions are allowed on the parent I2C
65      adapter for the complete multiplexed I2C transaction.
66      The properties of mux-locked and parent-locked multiplexers are discussed
67      in more detail in Documentation/i2c/i2c-topology.rst.
68
69required:
70  - compatible
71  - i2c-parent
72  - mux-controls
73
74unevaluatedProperties: false
75
76examples:
77  - |
78    #include <dt-bindings/gpio/gpio.h>
79    mux: mux-controller {
80        compatible = "gpio-mux";
81        #mux-control-cells = <0>;
82
83        mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>,
84                    <&pioA 1 GPIO_ACTIVE_HIGH>;
85    };
86
87    i2c-mux {
88        compatible = "i2c-mux";
89        mux-locked;
90        i2c-parent = <&i2c1>;
91
92        mux-controls = <&mux>;
93
94        #address-cells = <1>;
95        #size-cells = <0>;
96
97        i2c@1 {
98            reg = <1>;
99            #address-cells = <1>;
100            #size-cells = <0>;
101
102            gpio@20 {
103                compatible = "nxp,pca9555";
104                gpio-controller;
105                #gpio-cells = <2>;
106                reg = <0x20>;
107            };
108        };
109
110        i2c@3 {
111            reg = <3>;
112            #address-cells = <1>;
113            #size-cells = <0>;
114
115            gpio@20 {
116                compatible = "nxp,pca9555";
117                gpio-controller;
118                #gpio-cells = <2>;
119                reg = <0x20>;
120            };
121        };
122    };
123...
124