# hdf\_device\_desc.h - [Overview](#section2126061454165627) - [Summary](#section1232562669165627) - [Data Structures](#nested-classes) - [Macros](#define-members) - [Enumerations](#enum-members) - [Functions](#func-members) ## **Overview** **Related Modules:** [Core](Core.md) **Description:** Declares functions related to driver loading, service obtaining, and power management. **Since:** 1.0 ## **Summary** ## Data Structures

Data Structure Name	Description
HdfDeviceObject	Defines the device object.
HdfDeviceIoClient	Defines the client object structure of the I/O service.
IDeviceIoService	Defines the driver service.
SubscriberCallback	Called when the driver subscribes to other driver services.
IPowerEventListener	Defines the power management functions provided by the HDF for the driver.
HdfDriverEntry	Defines the entry structure of the driver in the HDF.

## Macros

Macro Name and Value	Description
MAX_PRIORITY_NUM 200	The maximum priority for loading the host and device.
HDF_INIT(module) HDF_DRIVER_INIT(module)	Registers the driver with the HDF.

## Enumerations

Enumeration Name	Description
ServicePolicy { SERVICE_POLICY_NONE = 0, SERVICE_POLICY_PUBLIC, SERVICE_POLICY_CAPACITY, SERVICE_POLICY_FRIENDLY, SERVICE_POLICY_PRIVATE, SERVICE_POLICY_INVALID }	Enumerates policies for releasing driver services developed based on the HDF.
DevicePreload { DEVICE_PRELOAD_ENABLE = 0, DEVICE_PRELOAD_DISABLE, DEVICE_PRELOAD_INVALID }	Enumerates driver loading policies.

## Functions

Function	Description
DevSvcManagerClntGetService (const char *svcName)	const struct HdfObject * Obtains the driver service object based on a driver service name.
HdfDeviceGetServiceName (const struct HdfDeviceObject *deviceObject)	const char * Obtains the service name of a driver.
HdfDeviceSubscribeService (struct HdfDeviceObject deviceObject, const char serviceName, struct SubscriberCallback callback)	int32_t Subscribes to a driver service.
HdfDeviceSendEvent (const struct HdfDeviceObject deviceObject, uint32_t id, const struct HdfSBuf data)	int32_t Sends event messages.
HdfDeviceSendEventToClient (const struct HdfDeviceIoClient client, uint32_t id, const struct HdfSBuf data)	int32_t Sends an event message to a specified client object.