moving Tegra30 to the common clock framework

[Peter De Schrijver]

Hi,

I started looking into what would be needed to move our tegra30 clock code
to the common clock framework. The tegra30 clocktree is rather flat. Basically
there are a bunch of sources (13 PLLs, external audio clocks, osc and 32Khz)
and peripheral clocks which have a mux (with 4 or more inputs), a divider and
a gate. So almost every peripheral clock can have multiple parents.

Some questions:

1) should these peripheral clocks be modelled as 3 different clocks
   (mux -> divider -> gate) or would it be better to make a new clock type for
   this?

2) how to define the default parent? in many cases the hw reset value isn't
   a very sensible choice, so the kernel probably needs to set a parent of
   many of them if we don't want to rely on bootloader configuration.

Cheers,

Peter.