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 interrupt controllers and interrupt multiplexing

Having a single interrupt from the CPU is usually not enough. Most systems have tens or hundreds of them. Now comes interrupt controller, which allows them to be multiplexed. Very often, architecture or platform-specific implementations offer specific facilities, such as the following:

  • Masking/unmasking individual interrupts
  • Setting priorities
  • SMP affinity
  • Exotic features, such as wake-up interrupts

IRQ management and interrupt controller drivers both rely on the concept of the IRQ domain, which is built on top of the following structures:

  • struct irq_chip: This is the interrupt controller data structure. This structure also implements a set of methods that allow to drive the interrupt controller and that are directly called by core IRQ code.
  • struct irqdomain: This provides the following options:
    • A pointer to the interrupt controller's firmware node (fwnode)
    • A function for converting...