Hi,
In our System on chip we have several power domains. As such there is no generic framework for the Power Domains in linux , and I find huge potential in the software to control the domains and exploit the power management capabilities.
There is one very small model that I could think of, something on the lines of clock framework.
1. Essentially the model would be based on defining the attributes of a power domain ( name, current state: on/off, usage count, wake up sources, list head etc) and the operations to be performed on a typical power domain ( Current State Check, Target State to be moved into etc) maintained in software data structures, that would be mapped onto hardware registers in the architecture specific code.
2. Maintain a list of the different power domains present.
3. The devices in a specific power domain, as per the requirements would get the power domain handler ( which would increment the usage count of the power domain) and would release it when not in need.
4. Typically a usage count of zero for any power domain -> switch off the power domain removing static power dissipation.
5. The same could be mapped on to the PM framework, where the devices would release their power handlers at the time of suspend and reaquire at time of resume operations.
6. The model could further be build upon to check any dependency in the power domains, eg DDR in on power domain should have the power domain on, if any of the devices in other power domain is trying to access DDR. This could be more architecture specific.
7. The advantages of the framework could be leveraged in the CPU idle time, by switching off the Power domains with zero usage counts.
The model could be build upon, but seek lot more inputs if there exists any provision on which we can build upon OR develop a generic power domain framework.
Regards
Deepak
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