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committed 127428356eddetermine the total number of legal selectors, then it will call the other functions===============================PINCTRL (PIN CONTROL) subsystem===============================This document outlines the pin control subsystem in LinuxThis subsystem deals with:- Enumerating and naming controllable pins- Multiplexing of pins, pads, fingers (etc) see below for details- Configuration of pins, pads, fingers (etc), such as software-controlled biasing and driving mode specific pins, such as pull-up/down, open drain, load capacitance etc.Top-level interface===================Definition of PIN CONTROLLER:- A pin controller is a piece of hardware, usually a set of registers, that can control PINs. It may be able to multiplex, bias, set load capacitance, set drive strength, etc. for individual pins or groups of pins.Definition of PIN:- PINS are equal to pads, fingers, balls or whatever packaging input or output line you want to control and these are denoted by unsigned integers in the range 0..maxpin. This numberspace is local to each PIN CONTROLLER, so there may be several such number spaces in a system. This pin space may be sparse - i.e. there may be gaps in the space with numbers where no pin exists.When a PIN CONTROLLER is instantiated, it will register a descriptor to thepin control framework, and this descriptor contains an array of pin descriptorsdescribing the pins handled by this specific pin controller.Here is an example of a PGA (Pin Grid Array) chip seen from underneath:: A B C D E F G H 8 o o o o o o o o 7 o o o o o o o o 6 o o o o o o o o 5 o o o o o o o o 4 o o o o o o o o 3 o o o o o o o o 2 o o o o o o o o 1 o o o o o o o oTo register a pin controller and name all the pins on this package we can dothis in our driver:: #include <linux/pinctrl/pinctrl.h>