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 8: Writing I2C Device Drivers

I2C stands for Inter-Integrated Circuit. It is a serial, multi-master, and asynchronous bus invented by Philips (now NXP), though multi-master mode is not widely used. I2C is a two-wire bus, respectively named Serial Data (SDA) and Serial Clock (SCL, or SCK). An I2C device is a chip that interacts with another device via an I2C bus. On this bus, both SDA and SCL are open-drain/open collectors, meaning that each can drive its output low, but neither can drive its output high without having pull-up resistors. SCL is generated by the master to synchronize data (carried by SDA) transfer over the bus. Both the slave and master can send data (not at the same time, of course), thus making SDA a bidirectional line. That said, the SCL signal is also bidirectional since the slave can stretch the clock by keeping the SCL line low. The bus is controlled by the master, which in our case is part of the System on Chip (SoC). This bus is frequently used in embedded...