Power +HAL Handler Tutorial

The base port must provide and register a HAL handler to handle these attributes.

The power attributes are in the EHalGroupPower HAL group. +The handler provides a kernel-side implementation to deal with the user-side +calls to HAL::Get() and HAL::Set() when +one of the following parameters is passed:

A typical application will have a user side monitor that periodically calls HAL::Get(), +passing HALData::EPowerBatteryStatus to get the charge +level of the battery.

Typically, the handler is implemented as part of a DPowerHal derived +object, which is created by the entry point of the base port power kernel +extension. The object is, therefore, part of the power controller kernel extension.

Implementation +notes

The DPowerHal derived +object constructor must register with the power manager by calling Register().
If there is some power-related +data that can be accessed via the HAL component and that persists through +power cycles (On/Off), it should be initialised here. Typically the TOnOffInfoV1 data +member of the Variant-specific TActualMachineConfig (usually +found in mconf.h file under the platform directory) contains +some of that persistent data.
The handler itself is +the function PowerHalFunction(), and must be fully implemented +in the base port.
The kernel hooks up +the handler to service the HAL functions at boot-time.
The power Hal functions +that the Handler can handle are enumerated by TPowerHalFunction. +Not all of these functions need to be handled. If not handled, the kernel +returns KErrNotSupported when the HAL function is called +with the relevant parameter. It is left to the base port to decide which functions +are relevant.