| Tom Rini | 53633a8 | 2024-02-29 12:33:36 -0500 | [diff] [blame] | 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. |