GPIO_CLIENT_QUERY_ACTIVE_INTERRUPTS callback function (gpioclx.h)

Article
10/21/2021

The CLIENT_QueryActiveInterrupts event callback function queries the state of a set of general-purpose I/O (GPIO) pins that are configured as interrupt inputs.

Syntax

GPIO_CLIENT_QUERY_ACTIVE_INTERRUPTS GpioClientQueryActiveInterrupts;

NTSTATUS GpioClientQueryActiveInterrupts(
  [in]      PVOID Context,
  [in, out] PGPIO_QUERY_ACTIVE_INTERRUPTS_PARAMETERS QueryActiveParameters
)
{...}

Parameters

[in] Context

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

[in, out] QueryActiveParameters

A pointer to a GPIO_QUERY_ACTIVE_INTERRUPTS_PARAMETERS structure that, on entry, describes the GPIO interrupt pins to query, and, on exit, contains the active and enabled interrupt state of these pins.

Return value

The CLIENT_QueryActiveInterrupts 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 query a set of GPIO pins that are configured as interrupt request inputs.

The QueryActiveParameters parameter points to a caller-allocated GPIO_QUERY_ACTIVE_INTERRUPTS_PARAMETERS structure. The caller sets the values of the BankId and EnabledMask members of this structure. The CLIENT_QueryActiveInterrupts function writes to the ActiveMask member of the structure.

On entry, the bits that are set in the EnabledMask member should match the set of currently enabled interrupts in the bank. On return, the bits that are set in the ActiveMask member should correspond to interrupts that are both enabled and active. Thus, if a bit in EnabledMask is zero, the corresponding bit in ActiveMask must be zero.

To register your driver's CLIENT_QueryActiveInterrupts 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_QueryActiveInterrupts function pointer.

GpioClx calls the CLIENT_QueryActiveInterrupts callback function 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, GpioClx calls the CLIENT_QueryActiveInterrupts function at DIRQL, which is the IRQL at which the ISR in GpioClx runs. Otherwise, this function is called at PASSIVE_LEVEL. For more information about this flag bit, see Optional and Required GPIO Callback Functions.

Examples

To define a CLIENT_QueryActiveInterrupts 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_QueryActiveInterrupts callback function that is named MyEvtGpioQueryActiveInterrupts, use the GPIO_CLIENT_QUERY_ACTIVE_INTERRUPTS function type, as shown in this code example:

GPIO_CLIENT_QUERY_ACTIVE_INTERRUPTS MyEvtGpioQueryActiveInterrupts;

Then, implement your callback function as follows:

_Use_decl_annotations_
NTSTATUS
  MyEvtGpioQueryActiveInterrupts(
    PVOID Context,
    PGPIO_QUERY_ACTIVE_INTERRUPTS_PARAMETERS QueryActiveParameters
    )
{ ... }

The GPIO_CLIENT_QUERY_ACTIVE_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_QUERY_ACTIVE_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.