[U-Boot] Merging device trees at runtime for module-based systems

[Daniel Mack <zonque@gmail.com>]

Hi,

a project I'm involved in uses a module/baseboard combo, and components
on either board are described in DT. I'm currently using separate dts
files which build upon each other with include statements, which works
fine for development.

In production though, we will certainly have running changes (and hence
different versions) over the lifetime of the product for both the
baseboard and the module, and the hardware has support for identifying
the versions of both sides at runtime.

So let's say we have n versions of the baseboard and m versions of the
module, we would much like to only prepare n + m files, instead of n * m
by pre-compiling every possible combination (some of which may actually
never occur 'in the wild').

So my question is: is it possible to do that kind of assembly of a
number of files at runtime in U-Boot? I guess all it takes is merging a
number of trees together, right? I browsed through the APIs but couldn't
yet find an clear approach to that kind of problem. If not, what would
it take to add that functionality? I can probably help with the
implementation if someone tells me what would be the right way.

Any pointer greatly appreciated.


Thanks,
Daniel