Writing Device Drivers


In the power management model, each device is composed of zero or more power-manageable components. If a device has no components, then the device is not power manageable.

Components correspond to parts of the device that can be put into a state that requires less power than normal. The definition of which components a device implements depends on the device driver writer, with one exception: component zero must represent all parts of the device that have hardware state that would be lost if power were to be completely removed from the device.

The device driver notifies the system of the device components by calling pm_create_components(9F) in its attach(9E) entry point as part of driver initialization.