Book Image

Linux Device Driver Development - Second Edition

By : John Madieu
Book Image

Linux Device Driver Development - Second Edition

By: John Madieu

Overview of this book

Linux is by far the most-used kernel on embedded systems. Thanks to its subsystems, the Linux kernel supports almost all of the application fields in the industrial world. This updated second edition of Linux Device Driver Development is a comprehensive introduction to the Linux kernel world and the different subsystems that it is made of, and will be useful for embedded developers from any discipline. You'll learn how to configure, tailor, and build the Linux kernel. Filled with real-world examples, the book covers each of the most-used subsystems in the embedded domains such as GPIO, direct memory access, interrupt management, and I2C/SPI device drivers. This book will show you how Linux abstracts each device from a hardware point of view and how a device is bound to its driver(s). You’ll also see how interrupts are propagated in the system as the book covers the interrupt processing mechanisms in-depth and describes every kernel structure and API involved. This new edition also addresses how not to write device drivers using user space libraries for GPIO clients, I2C, and SPI drivers. By the end of this Linux book, you’ll be able to write device drivers for most of the embedded devices out there.
Table of Contents (23 chapters)
1
Section 1 -Linux Kernel Development Basics
6
Section 2 - Linux Kernel Platform Abstraction and Device Drivers
12
Section 3 - Making the Most out of Your Hardware
18
Section 4 - Misc Kernel Subsystems for the Embedded World

Understanding the SPI framework abstractions in the Linux kernel

The Linux kernel SPI framework is made up of a few data structures, the most important of which are the following:

  • spi_controller, used to abstract the SPI master device.
  • spi_device, used to abstract a slave device sitting on the SPI bus.
  • spi_driver, the driver of the slave device.
  • spi_transfer, which is the low-level representation of one segment of a protocol. It represents a single operation between the master and slave. It expects Tx and/or Rx buffers as well as the length of the data to be exchanged and an optional CS behavior.
  • spi_message, which is an atomic sequence of transfers.

Let's now introduce each of these data structures, one after the other, starting with the most complex, which represents the SPI controller's data structure.

Brief introduction to struct spi_controller

Throughout this chapter, we will reference the controller because it is deeply coupled with...