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.
Table of Contents (14 chapters)
10
Additional Information: Managing Interrupts and Concurrency

Exchanging data with a char driver

Exchanging data with a peripheral means sending or receiving data to and from it, and, to do so, we have already seen that we have to use the write() and read() system calls, whose prototypes are defined in the kernel, as follows:

ssize_t write(struct file *filp,
const char __user *buf, size_t count,
loff_t *ppos);
ssize_t read(struct file *filp,
char __user *buf, size_t count,
loff_t *ppos);

On the other hand, their counterparts in user space look like the following:

ssize_t write(int fd, const void *buf, size_t count);
ssize_t read(int fd, void *buf, size_t count);

The preceding prototypes (both in the kernel or user space) look similar but, of course, they have different meanings and, as driver developers we must know perfectly what these meanings are to do our job accurately.

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