The AMD CS5536 Geode companion on the ALIX.3D3 board has several general purpose input/output pins. Most of them have different functions as well, and there are some registers to set if they should be used as special function GPIO pins. The ALIX.3D3 uses 4 GPIO pins for 3 LEDs and 1 mode switch. Accessing the leds is very easy using the leds-alix2 driver, but they can be addressed as GPIO as well. There is already a driver for the GPIO pins in the kernel named cs5535_gpio.c, but it uses a non standard interface to communicate with kernel. So, I wrote a new kernel driver using the GPIO interface. Continue reading

Kernel 2.6.29: Kernel Mode Setting with Intel GM965

Kernel 2.6.29 introduced the Kernel Mode Setting feature, meaning the kernel to be able to change resolution and adresse other outputs. For example kernels pre 2.6.29 always actived the external DVI device (if connected) on my macbook and showed boot screens there. This is now configurable. Also switching between X11 and console is much faster. Continue reading