Hi,

I have a mostly unsupported device (Creative Prodikeys PC-MIDI keyboard).
I would like to learn about driver programming under Linux, in specific USB driver programming. I am capable in C (although I'm not an ace) and I have read through the "Linux Kernel Module Programming Guide".

What I'm looking for is some documentation or perhaps a "howto" dealing with USB driver writing under Linux.


Any pointers would be appreciated.

Thanks!

You'll need a system you can trash. You'll also need this system, because as I recall (and this was many years ago), the only way to debug a device driver is through a serial connection to the target machine running your debug device driver.

You'll need to get hold of an existing USB driver, and look at its construction. That's easier in Linux, because there are so many source kits available.

Few people want to take on the task of writing a device driver. But if you must, be prepared for a lot of effort and hair pulling.

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Yea, I'm aware that it'll probably mean a lot of hair pulling... But I figure that it'll be a worthwhile exercise to gain some more knowledge of the Linux kernel..

I never thought about reading existing sources - I guess that's a good place to start. Thanks!

Device drivers are actually pretty straightforward.

Google for the O'Reilly book on Linux Device Drivers. You'll find Release 2 pretty quickly, but you really want Release 3. That one is available but is harder to find. I have a copy here that I downloaded as PDF files (I don't recall where from), and it has been a godsend for me.

The real problem you will have is if you don't have appropriate technical documentation for the device you are trying to control. Reverse engineering hardware by poking it in the interface is a simply HUGE job.

I actually placed an order for "Linux Device Drivers" 3rd Edition only today ... but it's going to take a while to arrive..

Yea.. I realise that without the technical docs things are even more complicated.. My plan is to use a USB snooping program with the device on Windows, it's after all purely an input device so it can't be that hard to figure the protocol out.. (I hope!!)

To bad Creative is of no use with the technical docs..

Yeah, you would think that a keyboard would be pretty simple. In fact, it is simple enough that you would think that some existing driver would work.

I suppose the midi portion is the issue, but if you can use the keyboard as a keyboard using any driver, then you are way ahead. Just take the driver that works and modify it to handle the midi stuff.

Yea, the midi portion is the chief issue, but not the only one..
The regular "qwerty" keys mostly work fine, except that at various stages some of them go "dead" for a while and the "ctrl" keys don't work all the time either.. it also has some extra buttons (media control, browser, email etc..) some of them do work but not all of them..

I first want to focus on getting all the regular and extended keys completely functional before I start looking at the midi stuff..

Anyway, thanks for all the tips.. I'll be sure to announce any progress on this "attempt" of mine.. (and of course I'll publicize the driver should I succeed in writing one )