Book Image

Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization

By : Kaiwan N Billimoria
Book Image

Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization

By: Kaiwan N Billimoria

Overview of this book

Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization is an ideal companion guide to the Linux Kernel Programming book. This book provides a comprehensive introduction for those new to Linux device driver development and will have you up and running with writing misc class character device driver code (on the 5.4 LTS Linux kernel) in next to no time. You'll begin by learning how to write a simple and complete misc class character driver before interfacing your driver with user-mode processes via procfs, sysfs, debugfs, netlink sockets, and ioctl. You'll then find out how to work with hardware I/O memory. The book covers working with hardware interrupts in depth and helps you understand interrupt request (IRQ) allocation, threaded IRQ handlers, tasklets, and softirqs. You'll also explore the practical usage of useful kernel mechanisms, setting up delays, timers, kernel threads, and workqueues. Finally, you'll discover how to deal with the complexity of kernel synchronization with locking technologies (mutexes, spinlocks, and atomic/refcount operators), including more advanced topics such as cache effects, a primer on lock-free techniques, deadlock avoidance (with lockdep), and kernel lock debugging techniques. By the end of this Linux kernel book, you'll have learned the fundamentals of writing Linux character device driver code for real-world projects and products.
Table of Contents (11 chapters)
Section 1: Character Device Driver Basics
User-Kernel Communication Pathways
Handling Hardware Interrupts
Working with Kernel Timers, Threads, and Workqueues
Section 2: Delving Deeper

Allocating the hardware IRQ

Often, a key part of writing a device driver is really the work of trapping into and handling the hardware interrupt that the chip you're writing the driver for emits. How do you do this? The trouble is that the way that hardware interrupts are routed from the interrupt controller chip(s) to the CPU(s) varies widely; it is very platform-specific. The good news is that the Linux kernel provides an abstraction layer to abstract away all the hardware-level differences; it's referred to as thgeneric interrupt (or IRQ) handling layer. Essentially, it performs the required work under the hood and exposes APIs and data structures that are completely generic. Thus, at least theoretically, your code will work on any platform. This generic IRQ layer is what we, primarily as driver authors, shall be using, of course; all the APIs and helper routines we use fall into this category.

Recall that it's really the core kernel that,...