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

Allocating and registering an input device

Before the events that are supported by an input device can be seen by the system, memory needs to be allocated for this device first using the devm_input_allocate_device() API. Then, the device needs to be registered with the system using input_device_register(). The former API will take care of freeing up the memory and unregistering the device when it leaves the system. However, non-managed allocation is still available but not recommended, input_allocate_device(). By using non-managed allocation, the driver becomes responsible for making sure that input_unregister_device() and input_free_device() are called to unregister the device and free its memory when they're on the unloading path of the driver, respectively. The following are the respective prototypes of these APIs:

struct input_dev *input_allocate_device(void)
struct input_dev *devm_input_allocate_device(
           ...