GPIO_CLIENT_DISCONNECT_IO_PINS callback function (gpioclx.h)

Article
10/21/2021

The CLIENT_DisconnectIoPins event callback function closes a logical connection to a set of general-purpose I/O (GPIO) pins that are configured for data read or write operations.

Syntax

GPIO_CLIENT_DISCONNECT_IO_PINS GpioClientDisconnectIoPins;

NTSTATUS GpioClientDisconnectIoPins(
  [in] PVOID Context,
  [in] PGPIO_DISCONNECT_IO_PINS_PARAMETERS DisconnectParameters
)
{...}

Parameters

[in] Context

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

[in] DisconnectParameters

A pointer to a GPIO_DISCONNECT_IO_PINS_PARAMETERS structure that describes the set of GPIO pins that are to be disconnected.

Return value

The CLIENT_DisconnectIoPins 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 to close a connection that was previously opened by a call to the CLIENT_ConnectIoPins callback function.

To register your driver's CLIENT_DisconnectIoPins 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_DisconnectIoPins function pointer.

Examples

To define a CLIENT_DisconnectIoPins 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_DisconnectIoPins callback function that is named MyEvtGpioDisconnectIoPins, use the GPIO_CLIENT_DISCONNECT_IO_PINS function type, as shown in this code example:

GPIO_CLIENT_DISCONNECT_IO_PINS MyEvtGpioDisconnectIoPins;

Then, implement your callback function as follows:

_Use_decl_annotations_
NTSTATUS
  MyEvtGpioDisconnectIoPins(
    PVOID Context,
    PGPIO_DISCONNECT_IO_PINS_PARAMETERS DisconnectParameters
    )
{ ... }

The GPIO_CLIENT_DISCONNECT_IO_PINS 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_DISCONNECT_IO_PINS 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.

Share via