Kernel Linux Pin Control Subsystem

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KERNEL LINUX PIN CONTROL SUBSYSTEM [email protected]

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• GPIO - (Or the various ways to turn on a led in linux) • Overview • GPIO x Pin Control • GPIOLib Kernel Space • Legacy • Parse your device tree • New Descriptor-Based API • Device tree abstracted • GPIO in User Space • sysfs - Deprecated! (Why? This is so easy) • Char Device - Why not write a device driver? • Pin Control (I really need this?) • Pin Multiplexing • Pin Configuration • Generic Pin Mutiplexing and Configuration *Maker point of view

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CASTELLO132 GPIO MUX OUT MUX IN PULL DOWN PULL UP

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ATMEGA328P PB6 / PIN13 MUX OUT MUX IN PULL UP

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ATMEGA328P PB6 / PIN13 MUX OUT MUX IN PULL UP

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GPIO PINCTRL MUX INPUT / OUTPUT REQUEST READ / WRITE PIN STATES SET MUX ALTENATES FUNCTIONS SELECT PIN CONFIGURATIONS

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GPIO PINCTRL MUX INPUT / OUTPUT REQUEST READ / WRITE PIN STATES SET MUX ALTENATES FUNCTIONS SELECT PIN CONFIGURATIONS

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Applications (Aka Distro) GNU C Library (glibc) KERNEL Architecture-Dependent Kernel Code System Call Interface KERNEL SPACE USER SPACE

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Applications (Aka Distro) GNU C Library (glibc) KERNEL Architecture-Dependent Kernel Code System Call Interface KERNEL SPACE USER SPACE ACCESS TO HARDWARE HAVE TO MADE IN KERNEL SPACE!

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• Linus Walleij • PINCTRL Subsystem • Creator • Maintainer

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This document is shared under the license: https://creativecommons.org/licenses/by-nc-sa/4.0

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REFERENCES https://elinux.org/images/b/b6/Pin_Control_Subsystem_Overview.pdf https://dflund.se/~triad/papers/Linaro_pinctrl_overview.pdf https://elinux.org/images/9/9b/GPIO_for_Engineers_and_Makers.pdf