Because I work on an awesome company, I could spend the last few days doing upstream kernel work for the OMAP3 SoC based embedded board I maintain.
Now that SPL/U-Boot and the kernel supports the latest version of the board, the natural next step was to add support for Device Tree (DT).
I didn’t know too much about DT besides it was the new shiny way to describe hardware (instead of the infamous board files) and that it could allow to boot most ARM board using a single kernel image.
So, after spending some time learning about DT, I posted a patch-set that adds DT support for IGEP technology devices (IGEPv2 and IGEP COM Module). Hopefully the patches won’t need too much love before they get merged.
DT is a hot topic on the Linux kernel community right now and it’s been actively developed. Support for it is still premature on some platforms (such as OMAP3). So, these DT don’t have all the hardware support for IGEP that is already implemented using board files.
Currently is working (tested with latest Linux v3.7-rc7 kernel on an IGEPv2 board):
– GPIO LEDs
– TWL4030 codec audio
– pinmux/pinconf pinctrl
There are still peripherals not yet supported such as Ethernet, Flash memory and Wifi/BT. Some of these are connected to the OMAP processor through its General Purpose Memory Controller (GPMC) interface and patches to add DT bindings for OMAP GPMC are still flying around. So support for them should be easily added once these patches hit mainline.
It should also work on an IGEP COM Module but since I don’t have this hardware it has been just “compile tested”.
Many thanks to Enric who provided me his initial DT that booted the board, reviewed my patches and gave me lots of feedback and suggestions. Enric’s initial DT and a great explanation on how to boot a kernel with DT can be found on his blog entry.
Also, I’ve updated the oe-core/poky/yocto meta-igep layer to include a mainline Linux kernel recipe. This will make easier to test IGEP support on upstream and to add any remaining hardware enablement bits.
Pingback: An update on Device Tree support for IGEP boards | Blog | Javier Martinez Canillas