xref: /linux/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.yaml (revision c532de5a67a70f8533d495f8f2aaa9a0491c3ad0) 
1# SPDX-License-Identifier: GPL-2.0-only
2%YAML 1.2
3---
4$id: http://devicetree.org/schemas/i2c/i2c-mux-pinctrl.yaml#
5$schema: http://devicetree.org/meta-schemas/core.yaml#
6
7title: Pinctrl-based I2C Bus Mux
8
9maintainers:
10  - Wolfram Sang <wsa@kernel.org>
11
12description: |
13  This binding describes an I2C bus multiplexer that uses pin multiplexing to route the I2C
14  signals, and represents the pin multiplexing configuration using the pinctrl device tree
15  bindings.
16
17                                 +-----+  +-----+
18                                 | dev |  | dev |
19    +------------------------+   +-----+  +-----+
20    | SoC                    |      |        |
21    |                   /----|------+--------+
22    |   +---+   +------+     | child bus A, on first set of pins
23    |   |I2C|---|Pinmux|     |
24    |   +---+   +------+     | child bus B, on second set of pins
25    |                   \----|------+--------+--------+
26    |                        |      |        |        |
27    +------------------------+  +-----+  +-----+  +-----+
28                                | dev |  | dev |  | dev |
29                                +-----+  +-----+  +-----+
30
31  For each named state defined in the pinctrl-names property, an I2C child bus will be created.
32  I2C child bus numbers are assigned based on the index into the pinctrl-names property.
33
34  The only exception is that no bus will be created for a state named "idle". If such a state is
35  defined, it must be the last entry in pinctrl-names. For example:
36
37    pinctrl-names = "ddc", "pta", "idle"  ->  ddc = bus 0, pta = bus 1
38    pinctrl-names = "ddc", "idle", "pta"  ->  Invalid ("idle" not last)
39    pinctrl-names = "idle", "ddc", "pta"  ->  Invalid ("idle" not last)
40
41  Whenever an access is made to a device on a child bus, the relevant pinctrl state will be
42  programmed into hardware.
43
44  If an idle state is defined, whenever an access is not being made to a device on a child bus,
45  the idle pinctrl state will be programmed into hardware.
46
47  If an idle state is not defined, the most recently used pinctrl state will be left programmed
48  into hardware whenever no access is being made of a device on a child bus.
49
50properties:
51  compatible:
52    const: i2c-mux-pinctrl
53
54  i2c-parent:
55    $ref: /schemas/types.yaml#/definitions/phandle
56    description: The phandle of the I2C bus that this multiplexer's master-side port is connected
57      to.
58
59allOf:
60  - $ref: i2c-mux.yaml
61
62unevaluatedProperties: false
63
64required:
65  - compatible
66  - i2c-parent
67
68examples:
69  - |
70    i2cmux {
71      compatible = "i2c-mux-pinctrl";
72      #address-cells = <1>;
73      #size-cells = <0>;
74
75      i2c-parent = <&i2c1>;
76
77      pinctrl-names = "ddc", "pta", "idle";
78      pinctrl-0 = <&state_i2cmux_ddc>;
79      pinctrl-1 = <&state_i2cmux_pta>;
80      pinctrl-2 = <&state_i2cmux_idle>;
81
82      i2c@0 {
83        reg = <0>;
84        #address-cells = <1>;
85        #size-cells = <0>;
86
87        eeprom@50 {
88          compatible = "atmel,24c02";
89          reg = <0x50>;
90        };
91      };
92
93      i2c@1 {
94        reg = <1>;
95        #address-cells = <1>;
96        #size-cells = <0>;
97
98        eeprom@50 {
99          compatible = "atmel,24c02";
100          reg = <0x50>;
101        };
102      };
103    };
104