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Using the maXTouch SPI Linux Driver

Introduction

This technical brief describes the maXTouch SPI Linux driver, the timing requirements for the Host SPI controller, and the debug options available in the kernel. An overview of how to configure and build the Linux driver on a test platform will be covered along with explanation of the various changes to the kernel drivers to support the function of the SPI Linux driver. The Linux driver can be compiled as an in-built driver or as a module.

The driver is designed to use the Linux Serial Peripheral Interface and follows the standard Linux driver model to perform input/output operations. The driver resides in the drivers/input/touchscreen directory of the kernel and interfaces with the hardware to generate 2D touch events using the Linux Input Subsystem API.

This technical brief assumes the user has a Linux based PC (either actual or a virtual machine) and has basic knowledge of the Linux OS and the use of Github. All testing has been done using the Ubuntu OS version 16.04. This technical brief will not go into detail with regards to the installation of any libraries and compilers, or the usage of tools unless critical for the operation of the maXTouch Linux driver.

The information within this document will reference the standard Linux kernel. Where possible, differences between the Linux “distributions” (for example, Android) in terms of tools, directory locations or behavior will be noted.