[RFC] clocktree representation in the devicetree

[arnd@arndb.de (Arnd Bergmann)]

On Monday 17 October 2011, Sascha Hauer wrote:
> The following is an attempt to represent the clocktree of a i.MX53 in
> the devicetree. I created this to see how it would look like and to
> start a discussion whether we want to move in this direction or not.

Very good, thanks for getting this started!

> Some things to consider:
> 
> - It seems to be very flexible. A board can customize the clock tree
>   by just adding some clk-parent=<phandle> properties to the muxers.
> - clocks can easily be associated with devices.
> 
> but:
> 
> - The following example registers 127 new platform devices and it's
>   not even complete. This adds significant overhead to initialization.

I don't understand enough about the clock trees to understand if the
dts representation is good, but it I don't see a reason to represent
it as lots of platform devices in linux. We can have lots of device_nodes
in the device tree that are not a platform_device but we can still
access them through the of_*() functions. Ideally, we would encapsulate
all the clock tree parsing in the clk subsystem and provide high-level
interfaces to clkdev drivers from there.

	Arnd