generic clock framework

Hi all

I'm Francesco and I work in STMicroelectronics

In the last ELC-E_2009 I spoke on a generic clock framework I'm working on
(see
http://tree.celinuxforum.org/CelfPubWiki/ELCEurope2009Presentations?action=AttachFile&do=view&target=ELC_E_2009_Generic_Clock_Framework.pdf).

I wrote the gcf to manage both clocks the platform_devices during a clock operation.

The main features are:
- it's integrated in the LDM
- it tracks the clock-to-clock relationship
- it tracks the clock-to-device relationship

- it has sysfs interface
- - the user can navigate the clock tree under /sys/clocks/...

- it uses the linux API (<linux/clk.h>) with some extra functions (to
register/unregister a clock
and other utility functions as clk_for_each())

- it involves the platform_device and the platform_driver in the clock
propagation.
- - basically each clock operation is managed as a transaction which
evolves step by step.
- - all the clock rates are evaluated (before the clk operation is
actually done)
- - each platform_device can check (before the clk operation is
actually done) the clk environment
it will have at the end of clock operation and if required it can
reject the operation.
- - each clock operation is actually executed only if all the
platform_devices accept the operation it-self

Moreover a common clock framework could be used to avoid a lot of duplicated and/or similar code
just a grep of 'EXPORT_SYMBOL\(clk_enable' under arch/arm finds 22
entries.

The patch is based on a 2.6.30 kernel also if it has a preliminary integration with the PM_RUNTIME
support.

It works on our st40 (an sh4 cpu based system) no test/porting was done on other platforms.

It would be mainly a starting point for a discussion and I'm available to extend/fix/share it.

Regards
Francesco