README.md
1# HDF<a name="EN-US_TOPIC_0000001078041442"></a>
2
3- [Introduction](#section11660541593)
4- [Directory Structure](#section161941989596)
5- [Usage](#section1312121216216)
6 - [HDF](#section129654513264)
7 - [Sensor](#section188637474417)
8 - [Display](#section161502341317)
9 - [Input](#section12629164020115)
10 - [WLAN](#section11408103183114)
11
12- [Repositories Involved](#section1371113476307)
13
14## Introduction<a name="section11660541593"></a>
15
16This repository stores the core source code information of the OpenHarmony driver subsystem, including the driver framework, configuration management, configuration parsing, universal framework model, and unified hardware driver interfaces. It is designed to provide a more precise and efficient development environment, where you can perform one-time development for multi-system deployment.
17
18**Figure 1** Architecture of the HDF<a name="fig19330181162816"></a>
19
20
21## Directory Structure<a name="section161941989596"></a>
22
23```
24/drivers/framework
25├── ability # Capabilities for the driver development, such as the message model libraries
26│ ├── config # Parsing code of the configuration
27│ └── sbuf # Data serialization code
28├── core # Core code for implementing the HDF
29│ ├── adapter # Kernel adaptation layer
30│ ├── common # Common basic code
31│ ├── host # Driver host environment module
32│ ├── manager # Management module
33│ └── shared # Code shared by the host and manager modules
34├── include # Header files for the HDF to provide capabilities externally
35│ ├── config # Header files declaring capabilities for parsing configuration
36│ ├── core # Header files exposed externally
37│ ├── net # Header files related to network operations
38│ ├── osal # Header files of the OS adaptation layer
39│ ├── platform # Header files declaring platform APIs
40│ ├── utils # Header files declaring common capabilities
41│ └── wifi # Header files for the WLAN module to provide capabilities externally
42├── model # Universal framework module for drivers
43│ ├── display # Display framework module
44│ ├── input # Input framework module
45│ ├── network # WLAN framework module
46│ └── sensor # Sensor driver module
47├── support # Basic capabilities
48│ └── platform # Platform driver framework and APIs, including GPIO, I2C, and SPI
49├── tools # Source code related to the tools of the HDF
50│ └── hc-gen # Source code of the configuration management tool
51└── utils # Basic data structures and algorithms
52```
53
54## Usage<a name="section1312121216216"></a>
55
56### HDF<a name="section129654513264"></a>
57
58To develop a driver based on the HDF, you only need to register and configure required APIs. The driver framework will load and initialize the driver based on the parsing content.
59
60Driver development based on the HDF consists of the following three parts:
61
62- Driver: Develop the functions.
63
64- Information configuration: Present the loading information of the driver.
65
66- Resource configuration: Configure the hardware information of the driver.
67
68You need to complete the logic code for the functions of a driver by the following APIs.
69
70The first part that catches your eyes is the driver entry, which is described through **DriverEntry**.
71
72Three APIs are available, namely **Bind**, **Init**, and **Release**.
73
74```
75struct HdfDriverEntry g_deviceSample = {
76 .moduleVersion = 1,
77 .moduleName = "sample_driver",
78 .Bind = SampleDriverBind,
79 .Init = SampleDriverInit,
80 .Release = SampleDriverRelease,
81};
82```
83
84**Bind**: This API is used to bind driver devices and its functions.
85
86```
87int32_t SampleDriverBind(struct HdfDeviceObject *deviceObject)
88{
89 // TODO: Bind device service to device object.
90 // And you can also initialize device resources here.
91 return HDF_SUCCESS;
92}
93```
94
95**Init**: When devices are successfully bound, the HDF calls **Init** to initialize the driver. After initialization is complete, the HDF will determine whether to create external service interfaces based on the configuration file. If the driver fails to be initialized, the driver framework will automatically release the created device interface.
96
97```
98int32_t SampleDriverInit(struct HdfDeviceObject *deviceObject)
99{
100 // TODO: Init hardware or other resources here.
101 return HDF_SUCCESS;
102}
103```
104
105**Release**: When you need to uninstall a driver, the HDF calls this function to release the driver resources. Then, other internal resources will be released.
106
107```
108void SampleDriverRelease(struct HdfDeviceObject *deviceObject)
109{
110 // Release all resources.
111 return;
112}
113```
114
115For details, see [HDF Overview](https://gitee.com/openharmony/docs/blob/master/en/device-dev/driver/driver-hdf.md).
116
117### Sensor<a name="section188637474417"></a>
118
119The sensor driver module is developed based on the HDF and supports functions such as cross-OS migration and differentiated device configuration.
120
121- APIs for implementing sensor driver module capabilities: Implement the capabilities of registering, loading, and deregistering sensor drivers as well as detecting sensor device depending on the HDF, normalize APIs for sensor devices of the same type, and offer APIs for parsing register configurations, abstract APIs for bus access, and abstract platform APIs.
122- APIs to be implemented by developers: Based on the HDF Configuration Source \(HCS\), implement differentiated configuration for sensors of the same type and serialized configuration of sensor device parameters, and offer APIs for some sensor device operations to simplify the sensor driver development.
123
124For details, see [Sensor Driver Overview](https://gitee.com/openharmony/docs/blob/master/en/device-dev/driver/driver-peripherals-sensor-des.md).
125
126### Display<a name="section161502341317"></a>
127
128The display driver model that is developed based on the HDF shields the differences among chip platforms, achieving cross-platform migration of the OS. It also abstracts the common service logic of peripherals and configures differentiated adaptation APIs so that a driver model can be compatible with different peripheral. In this way, third-party vendors can efficiently access the OpenHarmony driver ecosystem.
129
130- APIs for implementing display driver module capabilities: Implement the Hardware Driver Interfaces \(HDIs\) and their adaptation with the chip platform. In addition, the kernel-mode driver abstracts the common services of the panel driver and provides capabilities of initializing the panel, obtaining the panel configuration, powering on/off the panel, and implementing the backlight control.
131- APIs to be implemented by developers: Complete the board-level HCS configuration and private data configuration of the panel, or offer differentiated APIs for some components to ensure efficient development of the display driver.
132
133For details, see [LCD Overview](https://gitee.com/openharmony/docs/blob/master/en/device-dev/driver/driver-peripherals-lcd-des.md).
134
135### Input<a name="section12629164020115"></a>
136
137The input driver model is developed based on the HDF, provides unified driver APIs for upper-layer input services, and is decoupled from the chip platform. In addition, it abstracts several types of common platform drivers based on different input devices and is compatible with those input devices through configuration and differentiated peripheral APIs.
138
139- APIs for implementing input driver module capabilities: Implement the HDIs and provide capabilities of managing devices, controlling services, and reporting data. Besides, the input driver model provides a unified driver for different input devices and the capabilities of registering/unregistering an input device, reporting event data, parsing configuration, and loading a common driver.
140- APIs to be implemented by developers: Based on the provided platform driver, add the device descriptions as well as private configuration of the input device and implement differentiated APIs to greatly shorten the time required for developing input drivers.
141
142For details, see [Touchscreen Overview](https://gitee.com/openharmony/docs/blob/master/en/device-dev/driver/driver-peripherals-touch-des.md).
143
144### WLAN<a name="section11408103183114"></a>
145
146The WLAN module is developed based on the HDF and supports cross-OS migration, component adaptation, and modular assembly and compilation. Based on the unified APIs provided by the WLAN module, driver developers of WLAN vendors can adapt their driver code and developers of the Hardware Driver Interfaces \(HDIs\) are capable of creating, disabling, scanning, and connecting to WLAN hotspots.
147
148- APIs for implementing WLAN driver module capabilities: Implement the APIs of the WLAN HDI layer and provide capabilities of setting/obtaining the MAC address, obtaining the feature type, and setting the transmit power for upper-layer input services, as well as the capabilities of creating/releasing a **WifiModule**, connecting to/disconnecting from a WLAN hotspot, and applying for/releasing a **NetBuf** for developers.
149- APIs to be implemented by developers: Based on the provided platform driver, complete the board-level HCS configuration as well as the differentiated WLAN configuration, and offer APIs for initializing, deregistering, enabling, and disabling a network device.
150
151For details, see [WLAN Overview](https://gitee.com/openharmony/docs/blob/master/en/device-dev/driver/driver-peripherals-external-des.md).
152
153## Repositories Involved<a name="section1371113476307"></a>
154
155[Driver subsystem](https://gitee.com/openharmony/docs/blob/master/en/readme/driver-subsystem.md)
156
157[drivers\_framework](https://gitee.com/openharmony/drivers_framework/blob/master/README.md)
158
159[drivers\_adapter](https://gitee.com/openharmony/drivers_adapter/blob/master/README.md)
160
161[drivers\_adapter\_khdf\_linux](https://gitee.com/openharmony/drivers_adapter_khdf_linux/blob/master/README.md)
162
163[drivers\_peripheral](https://gitee.com/openharmony/drivers_peripheral/blob/master/README.md)
164
165
