CLIENT_PreProcessControllerInterrupt callback function

The CLIENT_PreProcessControllerInterrupt event callback function performs any pre-processing of a general-purpose I/O (GPIO) interrupt that must be done immediately if the ISR is scheduled to run at a later time.



NTSTATUS CLIENT_PreProcessControllerInterrupt(
  _In_ PVOID   Context,
  _In_ BANK_ID BankId
{ ... }


Context [in]

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

BankId [in]

The bank that contains the interrupting GPIO pin. If N is the number of banks in the GPIO controller, BankId is an integer in the range 0 to N–1. The GPIO framework extension previously obtained the number of banks in the controller from the CLIENT_QueryControllerBasicInformation event callback function. For more information, see Remarks in CLIENT_CONTROLLER_BASIC_INFORMATION.

Return value

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


This callback function is optional. A GPIO controller driver implements this function only if it performs most of its interrupt handling at PASSIVE_LEVEL, but must do some initial processing of an interrupt at DIRQL.

Typically, a GPIO controller driver can access a memory-mapped GPIO controller at DIRQL, but can access a serially connected GPIO controller only at PASSIVE_LEVEL. However, some serially connected GPIO controllers might lose interrupt status data if they delay capture of the interrupt status bits until the IRQL drops to PASSIVE_LEVEL. When the IRQL later drops to PASSIVE_LEVEL, the GPIO framework extension (GpioClx) can call the driver's CLIENT_QueryActiveInterrupts callback function to retrieve the register contents.

The GPIO controller driver indicates whether it must handle interrupts at PASSIVE_LEVEL in the device information that it passes to GpioClx during the CLIENT_QueryControllerBasicInformation callback. If the GPIO controller is memory-mapped, so that the driver can access the controller's registers at DIRQL, the driver sets the MemoryMappedController flag bit in the Flags member of the CLIENT_CONTROLLER_BASIC_INFORMATION structure that the driver passes to GpioClx. Otherwise, the driver sets MemoryMappedController = 0 to indicate that the driver must handle interrupts at PASSIVE_LEVEL. For more information, see Passive-Level ISRs.

To register your driver's CLIENT_PreProcessControllerInterrupt 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_PreProcessControllerInterrupt function pointer.


To define a CLIENT_PreProcessControllerInterrupt 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_PreProcessControllerInterrupt callback function that is named MyEvtGpioPreProcessInterrupt, use the GPIO_CLIENT_PRE_PROCESS_CONTROLLER_INTERRUPT function type, as shown in this code example:


Then, implement your callback function as follows:

    PVOID Context
{ ... }

The GPIO_CLIENT_PRE_PROCESS_CONTROLLER_INTERRUPT 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_PRE_PROCESS_CONTROLLER_INTERRUPT 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.


Target platform



Supported starting with Windows 8.




Called at DIRQL.

See also




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