Writing device drivers in Linux: A brief tutorial (2006) (opens in new tab)

Does anyone have any suggestions for books/learning materials related to the pre requisites mentioned in the article, specifically Microprocessor programming? I've tried to find some in the past but having no prior EE experience I find even some of the basics challenging.

I have experience with C, but don't really know where to start with the lower level stuff.

I'm thinking I should start with a simple book like Electrical Engineering 101 (http://www.amazon.com/Electrical-Engineering-101-Third-Schoo...). Once I have a grasp on some EE basics I might be able to step into the Microprocessor programming a bit better, knowing a bit of what's happening behind the scenes.

Any thoughts/suggestions?

If you're like me and read comments before you read the post, then I urge you to take a look at this how-to. Not only is it well written and informative but it makes fairly complicated concepts easy to understand. If you like the idea of writing drivers and want that kind of control over hardware but don't have a clue where to start, this is pretty much it.

Article is from 2006.

Why wasn't I aware of this guide last week when I had to write a kernel driver for my OS class?!

One thing that's surprised me with Linux development is how nice the APIs are to work with. Things like the file_operations struct, and the linked list stuff are very well thought out and easy to use (as easy as they could be for C programming).

My only complaint is that a lot of the written documentation is out of date about a number of topics. As the kernel has evolved it's gained and lost a number of APIs and depending on when resources were published they may say a number of conflicting things about how to carry out a task (registering a character device and getting it in /dev is the big one that comes to mind).

The way it's written almost makes me believe that kernel modules are that easy to write.

I really recommend a book called Linux Device Drivers (Third Edition) [1]. It's free, and split according to the major kernel subsystems. I used it many times as a reference when I had to recall some obscure API.

Another a great tool while developing for the kernel is the LXR [2] which is a browser-based indexer of the kernel source, for each of the kernel versions. Again great for checking out how to interface with a subsystem or how different calls are used.

[1] http://lwn.net/Kernel/LDD3/ [2] http://lxr.linux.no/

I worked as a linux kernel programmer for a time. All I really did was work slowly on bugs. It seems that there are always neat features that need implementing but the number of engineers with the now specialized skills required is relatively small compared to the general population of embedded engineers. It seems rare to find someone willing to cultivate an embedded engineer into a kernel developer. They're not hard and fast separations, but still, this division remains.

So, if you can, try to connect with actual kernel engineers, do an interesting project in school for a professor doing hardware work, etc.

One project that might help out is to re-write the 8150 USB network adapter project. The devices that have this chipset are easy and cheap to find and the data sheet is easily available. There's a PCI version of this chip, the 8139, too.

Wonderful - showing how little magic there really is in kernel programming. I recommend that everyone who does Linux programming go through this tutorial, even if just for fun - and for the sake of seeing how different the world on the other side of the syscall is. When writing a kernel-mode driver, a single bug usually means a reboot: either because you screwed up some refcount, so the module cannot be unloaded anymore - or because you clobbered something badly and the kernel is toast.

Having a driver-writing background, I silently laugh at the recent unit testing hype - I simply know from experience there are areas where you need much more care, gut and skill than def test_something(). And besides, you just can't unit-test a DMA transfer.

Speaking of 2006, is it still a releveant article? I'm sure that internal Linux structure didn't changed that much?

If you give this a try, take note: the drivers include the <linux/config.h> header file which was removed in 2.6.19. You should be able to remove it from the source with no ill effects (a quick test of the "memory" driver worked)...

They left out the bit about begging hardware manufacturers to release specifications.

I haven't bothered to check the docs, but isn't that a race condition in memory_init, registering the device before allocating the buffer?

Or are drivers loaded while holding a global lock? Even though driver (un)loading probably is fairly rare, that seems a bit heavy to me.

Worse, the 'goto fail' path, if it is ever hit, seems to leak a register_chrdev call.

I have zero experience with microprocessor programming , any recommendations in terms of resources and hardware to get for absolute beginners?

This is really a good introduction to device driver programming. Thanks for sharing this.

really good

I remember, this was my tutorial when my lead had told me to practice writing some dummy device drivers as our team was supposed to merge into kernel team. Well, the merge didn't happen and this was my first and last device driver.

I liked the clarity and ease it offered to a first timer. I was somehow miffed about moving to kernel team from Java(app dev) but after this tut and some more articles I was disappointed when finally I didn't. This was one of the articles that changed my leaning towards learning C in a positive way. C is now my interview language :-).