The End of an Era

Today I arrived at my office (which just happens to be wherever I sit down with my notebook), and was quite contented to read that Linus has seemingly decided to move on to the next major version change. This will probably also include a change in the numbering system that is currently used for kernal releases, much to the appeal of GregKH.

I have been using Linux since around the 2.2 days, and have been actively hacking / employed with Linux related projects on various architectures with both the 2.4 and 2.6 kernels. I guess you could say that I have Linus and many other kernel, arch, & subsystem maintainers to thank for that.
Sentimentally speaking, I find it immensely cool that I am currently writing this blog post using a phone running Linux/Android released by a company that leveraged the power of Linux for a significant part of their commercial success. If anyone is wondering, the phone is a Nexus S and the company is Google.

Here's to all Linux hackers, wherever your workstations may be.

update-20110529: 3.0!

Stmpe2401 Linux Driver

I just thought that I would post a message about one of my recent submissions to the Linux kernel.

The STMPE2401 is a multi-function device from ST Microelectronics intended for mobile, low-power applications. It provides an I²C interface for up to 24 extra GPIO lines, each with independent interrupt generation capabilities. Up to 20 of those lines can be used with the integrated 8x12 matrix keypad controller. Another 3 pins can be used for programmable PWM channels, and 3 other pins can be used for a rotator input. All of the subsystems can operate together, at the same time, and each subsystem also provides additional interrupt capabilities.

This device appears on the Peek handheld, among many others. I wrote this driver for another device which I am still unable to mention (sorry about that).

There's actually a newer chip, called the STMPE2403, I believe, which makes a couple of improvements over the original. Namely, it has an automatic sleep function that ensures the lowest power consumption possible, but it's still capable of running in 2401 compatibility mode.

In the linux kernel, this should eventually show up under drivers/mfd, with sub-components showing up in drivers/gpio/chip, drivers/input, and so on. Currently, I've only implemented the keypad functionality but have provided lots of structure for the other subsystems. Here is the patch.

Enjoy!

Linux-2.6.27-rc8 on the EEE 702

Although the Linux kernel version 2.6.27 has not yet been officially released, I was able to download, build and patch release-candidate-8 for my EEE PC with many notable improvements - most notably a working ath5k module. Correction: The Linux kernel version 2.6.27 was released 20081009 and you can read the changes here.

First of all, I was actually planning on using the 2.6.26-gentoo sources, which implemented the changes upstream that I had made for the 2.6.24-eee-r1 sources, because it already had the eeepc-laptop module sources included, and (limited) ath5k support.

However, when I tried to 'modprobe ath5k' with the 2.6.26-gentoo kernel, I encountered a nasty error message saying that the AR2425 chip is still under development (boo-urns!), and that support for the AR2425 chip would be included in the 2.6.27 sources. That made me revert back to my 2.6.24-eee-r1 linux kernel, but not for long!

Having never been the type to accept defeat so easily, I decided to use the vanilla-sources-2.6.27-rc8. The main difference between the vanilla and Gentoo sources are, that the Gentoo kernel sources (and subsequently the eee sources) are patched versions of the vanilla kernel, which include security fixes as well as various other features (SquashFS for example).

Now, I do need SquashFS for my squashed portage, but the security patches I could do without for the time being, until Kernel.org, and Gentoo, release their respective 2.6.27 kernel sources. Aside from that, I would need to compile external modules for the EEE pc, such as uvcvideo (webcam), eeepc-linux (Fan / CPU / FSB control).

Thanks to the inclusion of the eeepc-laptop sources, providing ACPI interfaces for all of the EEE PC Fn buttons, I could now omit the external asus-acpi module, as well as the quasi-proprietary ath_hal module provided with net-wireless/madwifi-ng.

Yes, that's right! Now the Atheros chipset on the EEE PC will work with the standard 'wext' wireless interface, allowing the unpatched version of NetworkManager to run seamlessly!!! Although I have switched to WICD since the last time I tried to use NetworkManager, but I thought I'd mention the changes anyway.

Here are a few patches that might be of interest:
eeepc-linux-2.6.27-rc8.patch
linux-2.6.27-rc8-squashfs3.4.patch
atl2-2.6.27-rc8.patch

All of these will work with sys-kernel/vanilla-sources-2.6.27_rc8.

Enjoy!