GPIO_CLIENT_QUERY_ENABLED_INTERRUPTS callback function (gpioclx.h)

Article
10/21/2021

The CLIENT_QueryEnabledInterrupts event callback function queries the state of a set of general-purpose I/O (GPIO) pins to determine which pins are both configured as interrupt inputs and enabled for interrupts.

Syntax

GPIO_CLIENT_QUERY_ENABLED_INTERRUPTS GpioClientQueryEnabledInterrupts;

NTSTATUS GpioClientQueryEnabledInterrupts(
  [in] PVOID Context,
  [in] PGPIO_QUERY_ENABLED_INTERRUPTS_PARAMETERS QueryEnabledParameters
)
{...}

Parameters

[in] Context

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

[in] QueryEnabledParameters

A pointer to a caller-allocated GPIO_QUERY_ENABLED_INTERRUPTS_PARAMETERS structure. Before calling this function, the caller writes a bank ID to the BankId member of this structure to specify which bank of GPIO pins to query. If successful, the function writes a mask value to the EnabledMask member of this structure to indicate which interrupts are enabled in the specified bank.

Return value

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

Remarks

Starting with Windows 8.1, the GPIO controller driver can, as an option, implement a CLIENT_QueryEnabledInterrupts callback function. If implemented, this function is called by the GPIO framework extension (GpioClx) to determine which interrupts are enabled in a bank of GPIO pins.

The QueryEnabledParameters parameter points to a caller-allocated GPIO_QUERY_ENABLED_INTERRUPTS_PARAMETERS structure. The caller sets the value of the BankId member of this structure. The CLIENT_QueryEnabledInterrupts function writes to the EnabledMask member of the structure.

To register your driver's CLIENT_QueryEnabledInterrupts 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_QueryEnabledInterrupts function pointer.

The CLIENT_QueryEnabledInterrupts function is optional. If your driver does not implement this function, set the CLIENT_QueryEnabledInterrupts member of the GPIO_CLIENT_REGISTRATION_PACKET structure to NULL.

If the CLIENT_QueryEnabledInterrupts function is implemented, GpioClx uses this function to improve driver reliability and diagnostics. GpioClx calls this function to verify that the set of interrupts enabled at the GPIO controller matches what GpioClx expects. Typically, a mismatch indicates a driver bug that can potentially cause an interrupt storm. GpioClx uses this function to do more extensive state validation in checked (debug) builds, and reduces the number of calls to this function in free (retail) builds to avoid impacting performance. If implemented, this function must directly read the hardware state instead of reading a cached or software-maintained version of the state.

GpioClx calls the CLIENT_QueryEnabledInterrupts 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_QueryEnabledInterrupts 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_QueryEnabledInterrupts 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_QueryEnabledInterrupts callback function that is named MyEvtGpioQueryEnabledInterrupts, use the GPIO_CLIENT_QUERY_ENABLED_INTERRUPTS function type, as shown in this code example:

GPIO_CLIENT_QUERY_ENABLED_INTERRUPTS MyEvtGpioQueryEnabledInterrupts;

Then, implement your callback function as follows:

_Use_decl_annotations_
NTSTATUS
  MyEvtGpioQueryEnabledInterrupts(
    PVOID Context,
    PGPIO_QUERY_ENABLED_INTERRUPTS_PARAMETERS QueryEnabledParameters
    )
{ ... }

The GPIO_CLIENT_QUERY_ENABLED_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_ENABLED_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 8.1.
Target Platform	Desktop
Header	gpioclx.h
IRQL	See Remarks.

Share via