Re: ARM clock API to PowerPC

[Mark Brown <broonie@sirena.org.uk>]

On Wed, Aug 12, 2009 at 05:57:05PM +1000, Benjamin Herrenschmidt wrote:

>  - From the above, question: Do we want to keep that parent pointer ?
> Does it make sense ? Will we have objects that are clock providers and
> themselves source from multiple parent ? Or we don't care and it becomes

That happens and at times one or more of the sources is off-chip.

> entirely the responsibility of a given struct clk instance to deal with
> its own parenthood ? Parenthood in the core has the advantage of making
> it potentially easier to represent clock nets in the device-tree.

> The core would thus be able to do a search in that list based on the
> clock-id passed in, or if clk_get(dev, NULL), then, use the first one.

What happens if another clock gets added or the list gets reordered for
some reason?

> Also, it would be nice to have a way to have "generic" clock provider
> drivers. For example, have a driver for the FooBar Clock chip, which is
> known to provide 4 fully programmable clocks. So there could be a
> generic driver for that, attached to the clock provider by the probe
> code or via the device-tree, the devices clock-map's just provide the
> clock ID within the chip (which output of the chip they are connected
> to), and so the remaining questions is what to program in each clocks.

Note that the present ARM implementations don't handle anything except
the core SoC normally.