EvtDeviceEnableWakeAtBus function
[Applies to KMDF only]
A bus driver's EvtDeviceEnableWakeAtBus event callback function performs bus-level operations that enable one of the bus's devices to trigger a wake-up signal on the bus.
Syntax
EVT_WDF_DEVICE_ENABLE_WAKE_AT_BUS EvtDeviceEnableWakeAtBus;
NTSTATUS EvtDeviceEnableWakeAtBus(
_In_ WDFDEVICE Device,
_In_ SYSTEM_POWER_STATE PowerState
)
{ ... }
Parameters
- Device [in]
-
A handle to a framework device object.
- PowerState [in]
-
A SYSTEM_POWER_STATE-typed enumerator that identifies the system power state that the system or device will wake from.
Return value
If the EvtDeviceEnableWakeAtBus callback function encountered no errors, it must return STATUS_SUCCESS or another status value for which NT_SUCCESS(status) equals TRUE. Otherwise it must return a status value for which NT_SUCCESS(status) equals FALSE.
If NT_SUCCESS(status) equals FALSE, the framework calls the driver's EvtDeviceDisableWakeAtBus callback function.
For more information about this callback function's return values, see Reporting Device Failures.
Remarks
For more information about this callback function, see Supporting System Wake-Up.
Examples
To define an EvtDeviceEnableWakeAtBus callback function, you must first provide a function declaration that identifies the type of callback function you’re defining. Windows provides a set of callback function types for drivers. Declaring a function using the callback function types helps Code Analysis for Drivers, Static Driver Verifier (SDV), and other verification tools find errors, and it’s a requirement for writing drivers for the Windows operating system.
For example, to define an EvtDeviceEnableWakeAtBus callback function that is named MyDeviceEnableWakeAtBus, use the EVT_WDF_DEVICE_ENABLE_WAKE_AT_BUS type as shown in this code example:
EVT_WDF_DEVICE_ENABLE_WAKE_AT_BUS MyDeviceEnableWakeAtBus;
Then, implement your callback function as follows:
_Use_decl_annotations_
NTSTATUS
MyDeviceEnableWakeAtBus (
WDFDEVICE Device,
SYSTEM_POWER_STATE PowerState
)
{...}
The EVT_WDF_DEVICE_ENABLE_WAKE_AT_BUS function type is defined in the Wdfpdo.h header file. To more accurately identify errors when you run the code analysis tools, be sure to add the _Use_decl_annotations_ annotation to your function definition. The _Use_decl_annotations_ annotation ensures that the annotations that are applied to the EVT_WDF_DEVICE_ENABLE_WAKE_AT_BUS function type in the header file are used. For more information about the requirements for function declarations, see Declaring Functions by Using Function Role Types for KMDF Drivers. For information about _Use_decl_annotations_, see Annotating Function Behavior.
Requirements
|
Minimum KMDF version | 1.0 |
|---|---|
|
Header |
|
|
IRQL | PASSIVE_LEVEL |
See also
