A sysfs interface for PowerOP that allows operating points to be created and activated from userspace. The platform-specific backend provides the code to read and write sysfs attributes for each power parameter; the core sysfs interface has no knowledge of the struct powerop_point contents. This interface could be seen as possible extension of cpufreq sysfs. It is not an integral part of PowerOP and is provided in part to facilitate discussion and experimentation with PowerOP, but could serve as a basis for a basic userspace power policy management stack. Operating points are created by writing the name of the operating point to /sys/powerop/new. This may be a job for configfs. /sys/powerop/<op>/ will contain an attribute for each power parameter that may be written to set the associated parameter for the new operating point. An operating point may be activated by writing its name to /sys/powerop/active. The hardware power parameters currently set may be read and written via /sys/powerop/hw/, a special operating point that reads and writes parameter attribute values immediately, primarily for diagnostic purposes. Buried in this interface is also the notion of a registry of "named operating points", allowing operating points created by some other interface (such as cpufreq or loading a module with the definitions as suggested previously by David Brownell) to be activated from userspace via /sys/powerop/active. Please note that the interface is not hooked up with the rest of the code yet and is provided just for reference/review.
