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

Device and driver matching mechanism explained

Device drivers and devices are always registered with the bus. When it comes to exporting the devices that are supported by the driver, you can use driver.of_match_table, driver.of_match_table, or <bus>_driver.id_table (which is specific to the device type; for example, i2c_device.id_table or platform_device.id_table).

Each bus driver has the responsibility of providing its match function, which is run by the kernel whenever a new device or device driver is registered with this bus. That said, there are three matching mechanisms for platform devices, all of which consist of string comparison. Those matching mechanisms are based on the DT table, ACPI table, device, and driver name. Let's see how the pseudo-platform and i2c buses implement their matching functions using those mechanisms:

static int platform_match(struct device *dev,
               ...