1# SPDX-License-Identifier: GPL-2.0-only
2%YAML 1.2
3---
4$id: http://devicetree.org/schemas/pinctrl/pinmux-node.yaml#
5$schema: http://devicetree.org/meta-schemas/core.yaml#
6
7title: Generic pin multiplexing node schema
8
9maintainers:
10  - Linus Walleij <linus.walleij@linaro.org>
11
12description: |
13  The contents of the pin configuration child nodes are defined by the binding
14  for the individual pin controller device. The pin configuration nodes need not
15  be direct children of the pin controller device; they may be grandchildren,
16  for example. Whether this is legal, and whether there is any interaction
17  between the child and intermediate parent nodes, is again defined entirely by
18  the binding for the individual pin controller device.
19
20  While not required to be used, there are 3 generic forms of pin muxing nodes
21  which pin controller devices can use.
22
23  pin multiplexing nodes:
24
25  Example:
26
27  state_0_node_a {
28    uart0 {
29      function = "uart0";
30      groups = "u0rxtx", "u0rtscts";
31    };
32  };
33  state_1_node_a {
34    spi0 {
35      function = "spi0";
36      groups = "spi0pins";
37    };
38  };
39  state_2_node_a {
40    function = "i2c0";
41    pins = "mfio29", "mfio30";
42  };
43
44  Optionally an alternative binding can be used if more suitable depending on the
45  pin controller hardware. For hardware where there is a large number of identical
46  pin controller instances, naming each pin and function can easily become
47  unmaintainable. This is especially the case if the same controller is used for
48  different pins and functions depending on the SoC revision and packaging.
49
50  For cases like this, the pin controller driver may use pinctrl-pin-array helper
51  binding with a hardware based index and a number of pin configuration values:
52
53  pincontroller {
54    ... /* Standard DT properties for the device itself elided */
55    #pinctrl-cells = <2>;
56
57    state_0_node_a {
58      pinctrl-pin-array = <
59        0 A_DELAY_PS(0) G_DELAY_PS(120)
60        4 A_DELAY_PS(0) G_DELAY_PS(360)
61        ...
62        >;
63    };
64    ...
65  };
66
67  Above #pinctrl-cells specifies the number of value cells in addition to the
68  index of the registers. This is similar to the interrupts-extended binding with
69  one exception. There is no need to specify the phandle for each entry as that
70  is already known as the defined pins are always children of the pin controller
71  node. Further having the phandle pointing to another pin controller would not
72  currently work as the pinctrl framework uses named modes to group pins for each
73  pin control device.
74
75  The index for pinctrl-pin-array must relate to the hardware for the pinctrl
76  registers, and must not be a virtual index of pin instances. The reason for
77  this is to avoid mapping of the index in the dts files and the pin controller
78  driver as it can change.
79
80  For hardware where pin multiplexing configurations have to be specified for
81  each single pin the number of required sub-nodes containing "pin" and
82  "function" properties can quickly escalate and become hard to write and
83  maintain.
84
85  For cases like this, the pin controller driver may use the pinmux helper
86  property, where the pin identifier is provided with mux configuration settings
87  in a pinmux group. A pinmux group consists of the pin identifier and mux
88  settings represented as a single integer or an array of integers.
89
90  The pinmux property accepts an array of pinmux groups, each of them describing
91  a single pin multiplexing configuration.
92
93  pincontroller {
94    state_0_node_a {
95      pinmux = <PINMUX_GROUP>, <PINMUX_GROUP>, ...;
96    };
97  };
98
99  Each individual pin controller driver bindings documentation shall specify
100  how pin IDs and pin multiplexing configuration are defined and assembled
101  together in a pinmux group.
102
103properties:
104  function:
105    $ref: /schemas/types.yaml#/definitions/string
106    description: The mux function to select
107
108  pins:
109    oneOf:
110      - $ref: /schemas/types.yaml#/definitions/uint32-array
111      - $ref: /schemas/types.yaml#/definitions/string-array
112    description:
113      The list of pin identifiers that properties in the node apply to. The
114      specific binding for the hardware defines whether the entries are integers
115      or strings, and their meaning.
116
117  groups:
118    $ref: /schemas/types.yaml#/definitions/string-array
119    description:
120      the group to apply the properties to, if the driver supports
121      configuration of whole groups rather than individual pins (either
122      this, "pins" or "pinmux" has to be specified)
123
124  pinmux:
125    description:
126      The list of numeric pin ids and their mux settings that properties in the
127      node apply to (either this, "pins" or "groups" have to be specified)
128    $ref: /schemas/types.yaml#/definitions/uint32-array
129
130  pinctrl-pin-array:
131    $ref: /schemas/types.yaml#/definitions/uint32-array
132