GET_SET_DEVICE_DATA callback function (wdm.h)

Article
02/25/2022

The GetBusData routine reads data from the device's configuration space.

Syntax

GET_SET_DEVICE_DATA GetSetDeviceData;

ULONG GetSetDeviceData(
  [in] PVOID Context,
  [in] ULONG DataType,
  [in] PVOID Buffer,
  [in] ULONG Offset,
  [in] ULONG Length
)
{...}

Parameters

[in] Context

A pointer to interface-specific context information. The caller passes the value that is passed as the Context member of the BUS_INTERFACE_STANDARD structure for the interface.

[in] DataType

The type of bus data to read. For more information, see the discussion of the WhichSpace parameter in IRP_MN_READ_CONFIG.

[in] Buffer

A pointer to the buffer that holds the configuration information to be read from the device's configuration space.

[in] Offset

The offset into the bus-specific device data where this read operation begins. For example, if the DataType parameter is PCI_WHICHSPACE_CONFIG, the Offset parameter value is the offset into PCI Configuration Space.

[in] Length

The length, in bytes, of data to read.

Return value

The GetBusData routine returns the length, in bytes, of the configuration data that is read after a successful read operation. If the read operation is unsuccessful, a value of zero is returned.

Remarks

Depending on the value of the DataType parameter, the GetBusData routine can be called only from the interrupt request levels (IRQLs) that are defined in the following table.

DataType value	IRQL
PCI_WHICHSPACE_CONFIG	<= DIRQL
PCI_WHICHSPACE_ROM	<= APC_LEVEL
PCCARD_COMMON_MEMORY PCCARD_COMMON_MEMORY_INDIRECT	<= DISPATCH_LEVEL
PCCARD_ATTRIBUTE_MEMORY PCCARD_ATTRIBUTE_MEMORY_INDIRECT	<= DISPATCH_LEVEL
PCCARD_PCI_CONFIGURATION_SPACE	<= DIRQL

The following remarks apply to drivers for PCI Express (PCIe) virtual functions (VFs) on devices that support the single root I/O virtualization (SR-IOV) interface:

Drivers for PCIe VFs should call the GetBusData routine at IRQL <= APC_LEVEL.
In order to read PCI Configuration data for the VF at IRQL = DISPATCH_LEVEL, the driver must issue I/O requests of IRP_MN_READ_CONFIG.

Requirements

Requirement	Value
Target Platform	Desktop
Header	wdm.h (include Ntddk.h)
IRQL	See Remarks section.