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

Dynamic memory allocation

The most straightforward way to allocate memory is to use the kmalloc() function, and, to be on the safe side, it’s best to use routines that clear the allocated memory to zero, such as the kzalloc() function. On the other hand, if we need to allocate memory for an array, there are kmalloc_array() and kcalloc() dedicated functions.

Here are some snippets containing memory allocation kernel functions (and the relative kernel memory deallocation functions) as reported in the header file, linux/include/linux/slab.h:

/**
* kmalloc - allocate memory
* @size: how many bytes of memory are required.
* @flags: the type of memory to allocate.
...
*/
static __always_inline void *kmalloc(size_t size, gfp_t flags);

/**
* kzalloc - allocate memory. The memory is set to zero.
* @size: how many bytes of memory are required.
* @flags: the type of memory to allocate...