tegrakernel/kernel/nvidia/Documentation/devicetree/bindings/pinctrl/pinctrl-tegra194-pexclk-padctrl.txt

Binding document for T194 PCIE PEXCLK Single/differential end selection
======================================================================

This document defines the device-specific binding for the T194 PCIE
PEXCLK pad control for single or differential ends.

Required properties:
--------------------
- compatible: Must be "nvidia,tegra194-pexclk-padctl"
- reg: Should contain a list of base address and size pairs for:
  - first entry: The base address and size of PCIE_PEXCLK_PADCTRL0
  - second entry: The base address and size of PCIE_PEXCLK_PADCTRL0

Please refer to pinctrl-bindings.txt @Documentation/devicetree/bindings/pinctrl
for details of the common pinctrl bindings used by client devices, including
the meaning of the phrase "pin configuration node".

Optional Pinmux properties:
--------------------------
Following properties are required if default setting of pins are required
at boot.
- pinctrl-names: A pinctrl state named per <pinctrl-binding.txt>.
- pinctrl[0...n]: Properties to contain the phandle for pinctrl states per
		<pinctrl-binding.txt>.

The pin configurations are defined as child of the pinctrl states node. Each
sub-node have following properties:

Required properties:
------------------
- pins: List of pins. Valid values of pins properties are:
		pexclk.

Child nodes contain the pinmux configurations following the conventions from
the pinctrl-bindings.txt document. Typically a single, static configuration is
given and applied at boot time.

Optional properties:
-------------------
nvidia,pexclk-single-end: Integer, Enable/disable single end on PCIE pexclk
			  pads. The valid values are 0 or 1.
			  0: Disable single end, means differential.
			  1: Enable single end, means single end clocks.

Optional prod nodes:
-------------------
Prod configuration can be provided per the prod DT binding for
prod initialisation. Default prod name is "prod";

Example:
========
	pinctrl@3790000 {
		compatible = "nvidia,tegra194-pexclk-padctl";
		reg = <0x0 0x03790000 0x0 0x1000>,
		      <0x0 0x037a0000 0x0 0x1000>;
		pinctrl-names = "default";
		pinctrl-0 = <&pexclk_pads_default>;

		pexclk_pads_default: pexclk_pads_default {
			pexclk {
				pins = "pexclk";
				nvidia,pexclk-single-end = <1>;
			};
		};
	};

The above DT configuration will configure pexclk in single ended.

For dynamic switching, the client node need to pass the required
phandle. Following are changes needed in the pinctrl and client
DT node.
	pinctrl@3790000 {
		compatible = "nvidia,tegra194-pexclk-padctl";
		reg = <0x0 0x03790000 0x0 0x1000>,
		      <0x0 0x037a0000 0x0 0x1000>;

		pexclk_pads_single: pexclk_pads_single {
			pexclk {
				pins = "pexclk";
				nvidia,pexclk-single-end = <1>;
			};
		};

		pexclk_pads_diff: pexclk_pads_diff {
			pexclk {
				pins = "pexclk";
				nvidia,pexclk-single-end = <0>;
			};
		};
	};


	client-node {
		/* Other properties of client node */

		pinctrl-names = "single". "differential";
		pinctrl-0 = <&pexclk_pads_single>;
		pinctrl-1 = <&pexclk_pads_diff>;
	};


Example with prod:
=================
	pinctrl@3790000 {
		compatible = "nvidia,tegra194-pexclk-padctl";
		reg = <0x0 0x03790000 0x0 0x1000>,
		      <0x0 0x037a0000 0x0 0x1000>;

		prod-settings {
			prod {
				prod = <
					/* Prod entries */
					>;
			};
		};
	};