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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Technical requirements

Following are some interesting URLs where we can get useful technical information regarding the board:

Taking a look at the technical specifications at http://espressobin.net/tech-spec/, we get the following information where we can see what the ESPRESSObin v5 can offer in terms of computational power, storage, networking, and expandability:

System on chip (SoC) Marvell Armada 3700LP (88F3720) dual core ARM Cortex A53 processor up to 1.2GHz
System memory 1 GB DDR3 or optional 2GB DDR3
Storage 1x SATA interface
1x micro SD card slot with footprint for an optional 4GB EMMC
Network connectivity 1x Topaz Networking Switch
2x GbE Ethernet LAN
1x Ethernet WAN
1x MiniPCIe slot for wireless/BLE peripherals
USB 1x USB 3.0
1x USB 2.0
1x micro USB port
Expansion 2x 46-pin GPIO headers for accessories and shields with I2C, GPIOs, PWM, UART, SPI, MMC, and so on.
Misc Reset button and JTAG interface
Power supply 12V DC jack or 5V via micro USB port
Power consumption

Less than 1W thermal dissipation at 1 GHz

In particular, the following screenshot shows the top view of the Marvell ESPRESSObin v5 (from now on, please take into account that I'm not going to explicitly add "v5" anymore):

In the preceding screenshot, we can see the following components:

  • The power connector (12V DC jack)
  • The reset switch
  • The micro USB device port (serial console)
  • The Ethernet ports
  • The USB host ports

The next screenshot shows the bottom view of the board where the microSD slot is located; this is where we should plug in the microSD we're going to create later on in this chapter:

In this book, we'll see how we can manage (and reinstall) a complete Debian distribution, something that will allow us to have a wide set of ready-to-run software packages, as in a normal PC (in fact, the Debian ARM64 version is equivalent to the Debian x86 version). Afterward, we will develop our device drivers for the board, and then, when possible, we will test them with real devices connected to the ESPRESSObin itself. A little tutorial about how to set up the host system is also present in this chapter, and you can use it to set up a GNU/Linux-based working machine or a dedicated virtual one.

The code and other files used in this chapter can be downloaded from GitHub at https://github.com/giometti/linux_device_driver_development_cookbook/tree/master/chapter_01.

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