[RFC] PowerOP, Intro 0/3

[RFC] PowerOP, Intro 0/3

[Eugeny S. Mints]

What's changed highlights:

- PowerOP Core is completely arch independent
- PowerOP Core provides interface to create/destroy, get/set
  operating points
- PowerOP Core maintains list of operating points  which can
  be referenced by names
- PowerOP Core allows an upper layer to operate on arbitrary
  subset of power parameters available on a certain platform
- More integration with cpufreq and omap cpufreq driver clean up
  (hw access code is removed)

PowerOP is a system power parameter management API submitted for
discussion.

This patch set is a follow-up to the PowerOP/cpufreq integration
discussion in the PM summit back in April and the continued discussion
of the small PM group and linux-pm list.

Overall proposed PM framework picture is the following:

                                                           user space
-----------------------------------------------------------------
        ----------                                      kernel space
     | CPU freq |
       ----------        
          ^                
           |                
          v              
  ------------------------
|          PowerOP       |
  -------------------------
                                               arch independent
------------------------------------------------------------------------
                                               arch specific
 --------------------------
|         PM Core         |
 -------------------------
  ------------------------------
|     Clock/Voltage FW    |
  ------------------------------

In the whole, PowerOP is designed to be completely arch independent
and and allows to create, write and read power parameters in a
form adopted by a layer above PowerOP (cpufreq for example).

PM Core provides access to all power parameters available on a
certain platform and in a pair with PowerOP allows for a power
control layer above PowerOP operates by arbitrary subset of
power parameters (cpufreq for ex. uses 2 out of 8 power parameters
available on an omap1 platform what will be shown in follow-up
patch but one can imaging other layer which utilize from 1 upto 8
power parameters).

Nowadays Linux has clock framework - well established interface to access
hw clocks and the layer which handles clocks interdependencies. Similar
voltage framework is on the way. Such combined clock/voltage framework
provides a good interface to get/set clock and voltage hw registers.
Clock/voltage framework utilization gives significant advantage in
power management providing dynamic clocks/voltages control in
addition to "on demand" power parameters settings capability provided by
PowerOP.

This reference implementation is an example of integrating cpufreq and
PowerOP on the OMAP 1710.