Book Image

Linux Device Driver Development Cookbook

By : Rodolfo Giometti
Book Image

Linux Device Driver Development Cookbook

By: Rodolfo Giometti

Overview of this book

Linux is a unified kernel that is widely used to develop embedded systems. As Linux has turned out to be one of the most popular operating systems worldwide, the interest in developing proprietary device drivers has also increased. Device drivers play a critical role in how the system performs and ensure that the device works in the manner intended. By exploring several examples on the development of character devices, the technique of managing a device tree, and how to use other kernel internals, such as interrupts, kernel timers, and wait queue, you’ll be able to add proper management for custom peripherals to your embedded system. You’ll begin by installing the Linux kernel and then configuring it. Once you have installed the system, you will learn to use different kernel features and character drivers. You will also cover interrupts in-depth and understand how you can manage them. Later, you will explore the kernel internals required for developing applications. As you approach the concluding chapters, you will learn to implement advanced character drivers and also discover how to write important Linux device drivers. By the end of this book, you will be equipped with the skills you need to write a custom character driver and kernel code according to your requirements.

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Table of Contents (14 chapters)
Preface
Preface
Who this book is for
What this book covers
To get the most out of this book
Sections
Get in touch
Free Chapter
1
Installing the Development System
Installing the Development System
Technical requirements
Setting up the host machine
Working with the serial console
Configuring and building the kernel
Setting up the target machine
Doing native compiling on foreign hardware
2
A Peek Inside the Kernel
A Peek Inside the Kernel
Technical requirements
Adding custom code to the sources
Using kernel messages
Working with kernel modules
Using module parameters
3
Working with Char Drivers
Working with Char Drivers
Technical requirements
Creating the simplest char driver
Exchanging data with a char driver
Using the "Everything Is a File" abstraction
4
Using the Device Tree
Using the Device Tree
Technical requirements
Using the device tree compiler and utilities
Getting application-specific data from a device tree
Using a device tree to describe a character driver
Downloading the firmware
Configuring CPU pins for specific peripherals
5
Managing Interrupts and Concurrency
Managing Interrupts and Concurrency
Technical requirements
Implementing an interrupt handler
Deferring work
Managing time with kernel timers
Waiting for an event
Performing atomic operations
6
Miscellaneous Kernel Internals
Miscellaneous Kernel Internals
Technical requirements
Using kernel data types
Managing helper functions
Dynamic memory allocation
Managing kernel linked lists
Using kernel hash tables
Getting access to I/O memory
Spending time in the kernel
7
Advanced Char Driver Operations
Advanced Char Driver Operations
Technical requirements
Going up and down within a file with lseek()
Using ioctl() for custom commands
Accessing I/O memory with mmap()
Locking with the process context
Locking (and syncing) with the interrupt context
Waiting for I/O operations with poll() and select()
Managing asynchronous notifications with fasync()
8
Additional Information: Working with Char Drivers
Additional Information: Working with Char Drivers
Exchanging data with a char driver
9
Additional Information: Using the Device Tree
Additional Information: Using the Device Tree
Device tree internals
Using the device tree compiler and utilities
Using a device tree to describe a character driver
Configuring the CPU pins for specific peripherals
Using a device tree to describe a character driver
10
Additional Information: Managing Interrupts and Concurrency
Additional Information: Managing Interrupts and Concurrency
Deferring work
Kernel timers
11
Additional Information: Miscellaneous Kernel Internals
Additional Information: Miscellaneous Kernel Internals
Dynamic memory allocation
Kernel doubly linked lists
Kernel hash tables
Getting access to I/O memory
Spending time in the kernel
12
Additional Information: Advanced Char Driver Operations
Additional Information: Advanced Char Driver Operations
Technical requirements
Going up and down within a file with lseek()
Using ioctl() for custom commands
Accessing I/O memory with mmap()
Locking with the process context
Waiting for I/O operations with poll() and select()
Managing asynchronous notifications with fasync()
13
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Managing Interrupts and Concurrency

When implementing a device driver, a developer has to resolve two main problems:

  • How to exchange data with peripherals
  • How to manage interrupts that peripherals generate to the CPU

The first point was covered (at least for char drivers) in previous chapters, while the second one (and its related matter) will be the main topic of this chapter.

In the kernel, we can consider the CPU (or the internal core executing some code) running in two main execution contexts — the interrupt context and the process context. The interrupt context is very easy to understand; in fact, the CPU is in this context each time it executes an interrupt handler (that is, special code the kernel executes each time an interrupt occurs). In addition to this, interrupts can be generated by the hardware or even by the software; that's why we talk about hardware...

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