Beagle: FDT support in BSP as a GSoC project?

[Joel Sherrill]

On Sun, Aug 11, 2019, 5:47 PM Chris Johns <chrisj at rtems.org> wrote:

> On 12/8/19 3:28 am, Joel Sherrill wrote:
> > On Sun, Aug 11, 2019, 10:59 AM Christian Mauderer <list at c-mauderer.de
> > <mailto:list at c-mauderer.de>> wrote:
> >
> >     Hello,
> >
> >     while mentoring Vijays GSoC project this year I noted that some
> drivers
> >     in the Beagle BSPs have quite horrible hard coded values for things
> like
> >     pinmux initialization. Maybe it would be a nice GSoC project for next
> >     year to replace this stuff with a fdt based initialization. I would
> like
> >     to ask for feedback before creating a ticket for it because it would
> >     mean a quite big change for the BSP (maybe even the name - see
> below).
> >
> >     Basically such a project would include the following parts:
> >
> >     - Parse the pinmux settings from FDT and create a two part driver
> for a
> >     'pinctrl-single' compatible FDT entry. One part generic, one device
> >     specific (similar to FreeBSD or Linux).
> >
> >     - Remove pinmux initialization from all drivers.
> >
> >     - Initialize drivers based on the FDT (instead of functions like
> >     bbb_register_i2c_1(...))
> >
> >     - Taking a more detailed look at the FDT what else could be
> initialized
> >     from it (maybe clocks?)
> >
> >     It could be a quite nice project for a RTEMS beginner. Due to the
> >     distributed initialization a lot of drivers have to be touched (at
> least
> >     i2c, spi and pwm). So a potential student would get a nice overview
> over
> >     the parts.
> >
> >     Note that this would be a big change for the BSP. Currently the BSP
> can
> >     be used without an FDT (as far as I know). Only libbsd needs one.
> After
> >     that a FDT would be mandatory. Despite that, I think that it would
> be an
> >     improvement.
> >
> >     Maybe it would be possible to merge the four beagle* BSPs that we
> have
> >     into only one "beagle" or "am33xx" BSP with that change. That would
> >     allow to support new Beagle variants like the Pocket Beagle without
> much
> >     effort (most likely only a change in the FDT).
> >
> >     What do you think? Should I create a ticket for it?
> >
>
> I love it. Yes please create a ticket.
>
> > I think this is a good idea if we can still avoid bloating apps with all
> > drivers. Make sure it has the right tags and shows up on the project
> page.
>
> The beagle has a lot of RAM. Is this as important for this BSP?
>

Not really but we don't want bad patterns starting.


> > There must be a good diagnostic if the device tree doesn't meet minimum
> > requirements. We don't want a failure to be hard to figure out. This is a
> > general statement for all device tree bsps.
>
> +1
>
> Chris
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.rtems.org/pipermail/devel/attachments/20190811/0b1e0f69/attachment.html>