Hardware Notifications

Windows provides an infrastructure for the hardware-agnostic support of notification components such as LEDs and vibration mechanisms. This support is delivered through the introduction of a Kernel-Mode Driver Framework (KMDF) class extension specifically for hardware notification components that allows for the rapid development of client drivers. A KMDF class extension is essentially a KMDF driver that provides a defined set of functionality for a given class of devices, similar to a port driver in the Windows Driver Model (WDM). This section provides an overview of the architecture of the hardware notification class extension.

For additional information about the KMDF, see Using WDF to Develop a Driver.

To provide support for hardware notifications, you need:

• hwnclx.h

Enumerations

HWN_CLX_EXPORT_INDEX Defines the position for each of the Hardware Notification exports in the export table.

Functions

HWN_CLIENT_GET_STATE Implemented by the client driver to get hardware notification component state. It is invoked when a user requests status information.
HWN_CLIENT_INITIALIZE_DEVICE Implemented by the client driver and is invoked as a result of a call to EVT_WDF_DEVICE_PREPARE_HARDWARE.
HWN_CLIENT_QUERY_DEVICE_INFORMATION Implemented by the client driver to retrieve hardware notification component attributes.
HWN_CLIENT_SET_STATE Implemented by the client driver to set hardware notification component state. It is invoked when a user wants to change the state of a driver.
HWN_CLIENT_START_DEVICE Implemented by the client driver to start the hardware notification component. It is invoked as a result of a call to EVT_WDF_DEVICE_D0_ENTRY.
HWN_CLIENT_STOP_DEVICE Implemented by the client driver TO start the hardware notification component. It is invoked as a result of a call to EVT_WDF_DEVICE_D0_EXIT.
HWN_CLIENT_UNINITIALIZE_DEVICE Implemented by the client driver and invoked as invoked as a result of a call to EVT_WDF_DEVICE_RELEASE_HARDWARE. This callback function uninitializes the hardware notification component.
HwNProcessAddDevicePostDeviceCreate Creates I/O queues. It should be called after the client driver’s EVT_WDF_DRIVER_DEVICE_ADD callback function is invoked and the device object has been created.
HwNProcessAddDevicePreDeviceCreate Supplies the device prepare/release and entry/exit callbacks to the Windows Driver Foundation (WDF) for transitioning the device into different states.
HwNRegisterClient Registers the hardware notification client driver and its callback functions with the class extension.
HwNUnregisterClient Unregisters the hardware notification client driver and its callback functions with the class extension. This function should be invoked when the client driver is unloaded.

Structures

CLIENT_DEVICE_INFORMATION The CLIENT_DEVICE_INFORMATION structure is used by the hardware notification callback HWN_CLIENT_QUERY_DEVICE_INFORMATION to return the total number of hardware notifications that the client device driver provides.
HWN_CLIENT_REGISTRATION_PACKET Hardware Notification client driver registration packet that is passed to the class extension when a client driver is registered. Contains version information and client driver callback functions.