GPIO_CLIENT_MASK_INTERRUPTS callback function (gpioclx.h)

Article
10/21/2021

The CLIENT_MaskInterrupts event callback function masks interrupts on a set of general-purpose I/O (GPIO) pins that are configured as interrupt inputs.

Syntax

GPIO_CLIENT_MASK_INTERRUPTS GpioClientMaskInterrupts;

NTSTATUS GpioClientMaskInterrupts(
  [in]      PVOID Context,
  [in, out] PGPIO_MASK_INTERRUPT_PARAMETERS MaskParameters
)
{...}

Parameters

[in] Context

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

[in, out] MaskParameters

A pointer to a GPIO_MASK_INTERRUPT_PARAMETERS structure that, on entry, describes the GPIO interrupt pins to mask, and, on exit, contains the status of the mask operation.

Return value

The CLIENT_MaskInterrupts 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 mask interrupts on GPIO pins that are configured as interrupt request inputs. For more information, see GPIO Interrupt Masks.

To register your driver's CLIENT_MaskInterrupts 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_MaskInterrupts function pointer.

The CLIENT_MaskInterrupts function is called from the interrupt service routine (ISR) in GpioClx. This ISR runs either at PASSIVE_LEVEL or DIRQL, depending on the device information that the CLIENT_QueryControllerBasicInformation callback function supplies to GpioClx. The CLIENT_QueryControllerBasicInformation function provides device information in the form of a CLIENT_CONTROLLER_BASIC_INFORMATION structure. If the MemoryMappedController flag bit is set in the Flags member of this structure, the GpioClx ISR runs at DIRQL and calls the CLIENT_MaskInterrupts function at DIRQL. Otherwise, the ISR runs at PASSIVE_LEVEL and calls the function at PASSIVE_LEVEL. For more information about this flag bit, see Optional and Required GPIO Callback Functions.

A CLIENT_MaskInterrupts call that fails to set the interrupt mask to the requested value must set the FailedMask member of the GPIO_MASK_INTERRUPT_PARAMETERS structure to a nonzero value and return an appropriate error status code. The CLIENT_MaskInterrupts function for a memory-mapped GPIO controller is expected to always succeed in setting the interrupt mask to the requested value. However, the CLIENT_MaskInterrupts function for a controller that is not memory-mapped must send an I/O request to the controller to set the mask, and this request might fail. If the request fails to set the mask, the function must indicate this failure in the value that it writes to the FailedMask member.

Examples

To define a CLIENT_MaskInterrupts 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_MaskInterrupts callback function that is named MyEvtGpioMaskInterrupts, use the GPIO_CLIENT_MASK_INTERRUPTS function type, as shown in this code example:

GPIO_CLIENT_MASK_INTERRUPTS MyEvtGpioMaskInterrupts;

Then, implement your callback function as follows:

_Use_decl_annotations_
NTSTATUS
  MyEvtGpioMaskInterrupts(
    PVOID Context,
    PGPIO_MASK_INTERRUPT_PARAMETERS MaskParameters
    )
{ ... }

The GPIO_CLIENT_MASK_INTERRUPTS 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_MASK_INTERRUPTS 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	See Remarks.