- Documentation/devicetree in the kernel sourcecode.
- PNP Device IDs
- Sun's IEEE1275 Open Firmware site
The Device Tree Compiler used to generate Open Firmware style device trees images is contained in the Fedora and openSUSE dtc rpm. You only need this package to develop device trees separate from the kernel.
The kernel source ships with its own version of dtc which is used to convert the in-tree DT files into linkable .o files so above package isn't even needed.
MIPS Platforms with Device Tree support
to DT is in progress and there is a git tree (linux-dt.git gitweb) for this project.
Firmware with Device Tree support
U-Boot pretty generic support for manipulating and passing a dtb at boot. Open Firmware doesn't currently support MIPS but is the grand daddy in the DT league and has been used for a long time on Sun SPARC systems, Apple and IBM PowerPC systems so a MIPS port may be a consideration.