OPAL_PCI_GET_PRESENCE_STATE
===========================

Get PCI slot presence state

Parameters
----------

``uint64_t id``
  PCI slot ID

``uint64_t data``
  memory buffer pointer for presence state

Calling
-------

Retrieve PCI slot's presence state. The detected presence means there are
adapters inserted to the PCI slot. Otherwise, the PCI slot is regarded as
an empty one. The typical use is to ensure there are adapters existing
before probing the PCI slot in PCI hot add path. The retrieved presence
state is stored in buffer pointed by @data.

Return Codes
------------
OPAL_SUCCESS
  PCI slot's presence state is retrieved successfully

OPAL_PARAMETER
  The indicated PCI slot isn't found

OPAL_UNSUPPORTED
  Presence retrieval not supported on the PCI slot