GPIO_CLIENT_QUERY_CONTROLLER_BASIC_INFORMATION callback function (gpioclx.h)

Article
10/21/2021

The CLIENT_QueryControllerBasicInformation event callback function retrieves the hardware attributes of the general-purpose I/O (GPIO) controller.

Syntax

GPIO_CLIENT_QUERY_CONTROLLER_BASIC_INFORMATION GpioClientQueryControllerBasicInformation;

NTSTATUS GpioClientQueryControllerBasicInformation(
  [in]  PVOID Context,
  [out] PCLIENT_CONTROLLER_BASIC_INFORMATION Information
)
{...}

Parameters

[in] Context

A pointer to the GPIO controller driver's device context.

[out] Information

A pointer to a caller-allocated CLIENT_CONTROLLER_BASIC_INFORMATION structure. The CLIENT_QueryControllerBasicInformation function writes the GPIO controller hardware attributes and configuration information into this structure.

Return value

The CLIENT_QueryControllerBasicInformation function returns STATUS_SUCCESS if the call is successful. Otherwise, it returns an appropriate error code.

Remarks

This callback function is implemented by the GPIO controller driver. The GPIO framework extension (GpioClx) calls this function.

The CLIENT_QueryControllerBasicInformation callback function should set all members of the CLIENT_CONTROLLER_BASIC_INFORMATION structure, including the Version and Size members. GpioClx does not initialize the Size member before calling this function, but the buffer that the Information parameter points to is guaranteed to be large enough to contain the version of this structure that the GPIO controller driver uses.

To register your driver's CLIENT_QueryControllerBasicInformation callback function, call the GPIO_CLX_RegisterClient method. This method accepts, as an input parameter, a pointer to a GPIO_CLIENT_REGISTRATION_PACKET structure that contains a CLIENT_QueryControllerBasicInformation function pointer.

Examples

To define a CLIENT_QueryControllerBasicInformation 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 a CLIENT_QueryControllerBasicInformation callback function that is named MyEvtGpioQueryControllerBasicInformation, use the GPIO_CLIENT_QUERY_CONTROLLER_BASIC_INFORMATION function type, as shown in this code example:

GPIO_CLIENT_QUERY_CONTROLLER_BASIC_INFORMATION MyEvtGpioQueryDeviceInformation;

Then, implement your callback function as follows:

_Use_decl_annotations_
NTSTATUS
  MyEvtGpioQueryDeviceInformation(
    PVOID Context,
    PCLIENT_CONTROLLER_BASIC_INFORMATION Information
    )
{ ... }

The GPIO_CLIENT_QUERY_CONTROLLER_BASIC_INFORMATION function type is defined in the Gpioclx.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 GPIO_CLIENT_QUERY_CONTROLLER_BASIC_INFORMATION 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 more information about Use_decl_annotations, see Annotating Function Behavior.

Requirements

Requirement	Value
Minimum supported client	Supported starting with Windows 8.
Target Platform	Desktop
Header	gpioclx.h
IRQL	Called at PASSIVE_LEVEL.

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