Either way, this will require a detailed model of the system in terms of
latency, throughput, current consumption and heat generation.
Which can be provided only by the HW manufacturer.
But, should such model be available (and we have some form of it for the
OMAP3 in N900), then it can be abstracted through generic interfaces,
which accept constraints and produce the selected target state
(typically a vector of states for each sub component).