11.6. Thermal Zone Interface Requirements

While not all thermal zone interfaces are required to be present in each thermal zone, OSPM levies conditional requirements for the presence of specific thermal zone interfaces based on the existence of other related thermal zone interfaces. These interfaces may be implemented by thermal zone-wide objects or by OS-specific device driver exposed thermal interfaces. The requirements are outlined below:

• A thermal zone must contain at least one temperature interface; either the _TMP object or a member device temperature interface.

• A thermal zone must contain at least one trip point (critical, near critical, active, or passive).

• If _ACx is defined then an associated _ALx must be defined (e.g. defining _AC0 requires _AL0 also be defined).

• If _PSV is defined then either the _PSL or _TZD objects must exist. The _PSL and _TZD objects may both exist.

• If _PSL is defined then:

  • If a linear performance control register is defined (via either P_BLK or the _PTC, _TSS, _TPC objects) for a processor defined in _PSL or for a processor device in the zone as indicated by _TZM then the _TC1, _TC2, and objects must exist. A_TFP or _TSP object must also be defined if the device requires polling.

  • If a linear performance control register is not defined (via either P_BLK or the _PTC, _TSS, _TPC objects) for a processor defined in _PSL or for a processor device in the zone as indicated by _TZM then the processor must support processor performance states (in other words, the processor’s processor object must include _PCT, _PSS, and _PPC).

• If _PSV is defined and _PSL is not defined then at least one device in thermal zone, as indicated by either the _TZD device list or devices’ _TZM objects, must support device performance states.

• _SCP is optional.

• _TZD is optional outside of the _PSV requirement outlined above.

• If _HOT is defined then the system must support the S4 sleeping state.