GSOC: Adding FDT infrastructure to RTEMS

[Niteesh]

This is what I have understood till now, please correct me if I am wrong
All this explanation is in context with FreeBSD.
The drivers register themselves using* EARLY_DRIVER_MODULE*, this done with
the help of linker sets right? Where all the data structures for the
drivers stored things like
compatible strings etc. Is it also in linkerset?
At some point during initialization, the *ofwbus(fdtbus) *is initialized,
it is attached to some kind of
bus not sure which one, is it *nexus or newbus*? To which another abstract
bus called *simplebus *is
attached, all peripherals are then attached to this bus.
I couldn't find anything called *fdtbus*, in the FreeBSD code, All I could
find was *ofwbus*, but all reference
talk only about *fdtbus*, am I missing something?
After *simplebus* init is done, the *ofwbus_attach(ofwbus.c:137) *goes
through all nodes and attaches
them to *simplebus*. But I am really sure of what happens after, it would
be really helpful if someone could
explain it or at least provide some resources.

The resources that I used:
https://www.bsdcan.org/2010/schedule/attachments/136_FreeBSD_FDT-slides.pdf
https://www.semihalf.com/pub/bsdcan/2010_FreeBSD_FDT-paper.pdf
Man pages from FreeBSD.


On Mon, Jan 20, 2020 at 10:30 PM Niteesh <gsnb.gn at gmail.com> wrote:

> I interested in adding FDT infrastructure similar to FreeBSD and Linux to
> RTEMS as a GSOC project. I have very little knowledge of how all this
> works,
> but I have started learning by digging into FreeBSD code, using online
> forums and also thanks to Christian for patiently answering all my
> questions.
>
> My plan is to add a subsystem, which will parse the DTB file and
> initialize all active
> devices present in the system. It will ask for drivers that can handle the
> devices and
> the best driver is selected and attached to the driver.
> As I told before, I have very little idea of the complexity, I have no
> idea of what problems
> I would face?
>
> I will discuss what I have learned till now in a following mail, please
> correct me if I
> am wrong.
>
> What do you guys think about this? what all should be implemented in a
> GSOC timeline?
> I know this is not very detailed, but I will create a more detailed
> proposal based
> on your comments soon.
>
> Thank you,
> Niteesh
>
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