1 Conexant Digicolor CX92755 General Purpose Pin Mapping
2
3 This document describes the device tree binding of the pin mapping hardware
4 modules in the Conexant Digicolor CX92755 SoCs. The CX92755 in one of the
5 Digicolor series of SoCs.
6
7 === Pin Controller Node ===
8
9 Required Properties:
10
11 - compatible: Must be "cnxt,cx92755-pinctrl"
12 - reg: Base address of the General Purpose Pin Mapping register block and the
13 size of the block.
14 - gpio-controller: Marks the device node as a GPIO controller.
15 - #gpio-cells: Must be <2>. The first cell is the pin number and the
16 second cell is used to specify flags. See include/dt-bindings/gpio/gpio.h
17 for possible values.
18
19 For example, the following is the bare minimum node:
20
21 pinctrl: pinctrl@f0000e20 {
22 compatible = "cnxt,cx92755-pinctrl";
23 reg = <0xf0000e20 0x100>;
24 gpio-controller;
25 #gpio-cells = <2>;
26 };
27
28 As a pin controller device, in addition to the required properties, this node
29 should also contain the pin configuration nodes that client devices reference,
30 if any.
31
32 For a general description of GPIO bindings, please refer to ../gpio/gpio.txt.
33
34 === Pin Configuration Node ===
35
36 Each pin configuration node is a sub-node of the pin controller node and is a
37 container of an arbitrary number of subnodes, called pin group nodes in this
38 document.
39
40 Please refer to the pinctrl-bindings.txt in this directory for details of the
41 common pinctrl bindings used by client devices, including the definition of a
42 "pin configuration node".
43
44 === Pin Group Node ===
45
46 A pin group node specifies the desired pin mux for an arbitrary number of
47 pins. The name of the pin group node is optional and not used.
48
49 A pin group node only affects the properties specified in the node, and has no
50 effect on any properties that are omitted.
51
52 The pin group node accepts a subset of the generic pin config properties. For
53 details generic pin config properties, please refer to pinctrl-bindings.txt
54 and <include/linux/pinctrl/pinconfig-generic.h>.
55
56 Required Pin Group Node Properties:
57
58 - pins: Multiple strings. Specifies the name(s) of one or more pins to be
59 configured by this node. The format of a pin name string is "GP_xy", where x
60 is an uppercase character from 'A' to 'R', and y is a digit from 0 to 7.
61 - function: String. Specifies the pin mux selection. Values must be one of:
62 "gpio", "client_a", "client_b", "client_c"
63
64 Example:
65 pinctrl: pinctrl@f0000e20 {
66 compatible = "cnxt,cx92755-pinctrl";
67 reg = <0xf0000e20 0x100>;
68
69 uart0_default: uart0_active {
70 data_signals {
71 pins = "GP_O0", "GP_O1";
72 function = "client_b";
73 };
74 };
75 };
76
77 uart0: uart@f0000740 {
78 compatible = "cnxt,cx92755-usart";
79 ...
80 pinctrl-0 = <&uart0_default>;
81 pinctrl-names = "default";
82 };
83
84 In the example above, a single pin group configuration node defines the
85 "client select" for the Rx and Tx signals of uart0. The uart0 node references
86 that pin configuration node using the &uart0_default phandle.
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