Documentation/devicetree/bindings/pinctrl/cnxt,cx92755-pinctrl.txt

   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.