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

Chapter 7: Understanding the Concept of Platform Devices and Drivers

The Linux kernel handles devices by using the concept of buses, that is, the links between the CPU and these devices. Some buses are smart enough and embed a discoverability logic to enumerate devices sitting on them. With such buses, early in the bootup phase, the Linux kernel requests these buses for the devices they have enumerated as well as the resources (such as interrupt lines and memory regions) they need to work correctly. PCI, USB, and SATA buses all come under this family of discoverable buses.

Unfortunately, the reality is not always so beautiful. There are a number of devices that the CPU is still unable to detect. Most of these non-discoverable devices are on-chip, although some of them sit on slow or dumb buses that do not support device discoverability.

As a result, the kernel must provide mechanisms for receiving information about the hardware and users must inform the kernel where these devices...