Standard System Porting Guide

• Defining a Development Board

  • Defining an SoC
  • Defining a Product
  • Verifying the Porting

• Porting the Kernel

  • 1. Adding a Kernel-built Subsystem to the SoC
  • 2. Building the Kernel
  • 3. Verifying the Porting

• Porting the HDF Driver

  • 1. LCD
  • 2. Touchscreen
  • 3. WLAN
  • 4. Samples

This document describes the general process for porting a development board, rather than the porting process specific to a System on Chip (SoC). In the future, the community will provide more development board porting examples for your reference.

Defining a Development Board

This document uses the process of porting a development board named MyProduct as an example. This development board is provided by MyProductVendor and uses the SoC MySOC produced by MySoCVendor.

Defining an SoC

Create a JSON file named after the SoC name in the //productdefine/common/device directory and specify the CPU architecture.

For example, to port MySOC, which uses a 32-bit ARM kernel, configure the file as follows:

//productdefine/common/device/MySOC.json

{
    "target_os": "ohos",
    "target_cpu": "arm"
}

Currently, target_cpu can be set to arm only. In the future, you can set the value depending on the CPU architecture, such as arm64, riscv, or x86.

Defining a Product

Create a JSON file named after the product name in the //productdefine/common/products directory. This file is used to describe the SoC used by the product and the required subsystems. Configure the file as follows:

//productdefine/common/products/MyProduct.json

{
  "product_name": "MyProduct",
  "product_company" : "MyProductVendor",
  "product_device": "MySOC",
  "version": "2.0",
  "type": "standard",
  "parts":{
    "ace:ace_engine_standard":{},
    "ace:napi":{},
    ...
    "xts:phone_tests":{}
  }
}

The main configurations are as follows:

1. product_device: SoC used by the product.
2. type: system level. In this example, set it to standard.
3. parts: subsystem to enable. A subsystem can be treated as an independently built functional block.

You can find available subsystems in //build/subsystem_config.json. You can also customize subsystems.

You are advised to copy the configuration file of Hi3516D V300 and delete the hisilicon_products subsystem, which is used to compile the kernel for Hi3516D V300.

Verifying the Porting

Run the following command to start the build of your product:

./build.sh --product-name MyProduct 

After the build is complete, you can view the built OpenHarmony image file in //out/ohos-arm-release/packages/phone/images.

Porting the Kernel

Now, you need to port the Linux kernel to enable it to run successfully.

1. Adding a Kernel-built Subsystem to the SoC

Add the following subsystem configuration to the //build/subsystem_config.json file:

  "MySOCVendor_products": {
    "project": "hmf/MySOCVendor_products",
    "path": "device/MySOCVendor/MySOC/build",
    "name": "MySOCVendor_products",
    "dir": "device/MySOCVendor"
  },

Then, open the configuration file //productdefine/common/products/MyProduct.json, which is used to define the product, and add the new subsystem to the product.

2. Building the Kernel

The OpenHarmony source code provides the Linux kernel 4.19, which is archived in //kernel/linux-4.19. This section uses this kernel version as an example to describe how to build the kernel.

The path for building the subsystem is defined when you define the subsystem in the previous step. The path is //device/MySOCVendor/MySOC/build. Now, you need to create a build script in this path to instruct the build system to build the kernel.

The recommended directory structure is as follows:

├── build
│ ├── kernel
│ │     ├── linux
│ │           ├──standard_patch_for_4_19.patch // Patch for the Linux kernel 4.19
│ ├── BUILD.gn
│ ├── ohos.build

The BUILD.gn file is the only entry for building the subsystem.

The expected build result is as follows:

3. Verifying the Porting

Now start build, and check whether the kernel image is generated as expected.

Porting the HDF Driver

1. LCD

This section describes how to port a Liquid Crystal Display (LCD) driver. The hardware driver framework (HDF) designs a driver model for the LCD. To support an LCD, you must compile a driver, generate a model instance in the driver, and register the instance.

The LCD drivers are stored in the //drivers/framework/model/display/driver/panel directory.

• Create a panel driver.

In the Init method of the driver, call RegisterPanel to register the model instance.

int32_t XXXInit(struct HdfDeviceObject *object)
{
    struct PanelData *panel = CreateYourPanel();

    // Register the model instance.
    if (RegisterPanel(panel) != HDF_SUCCESS) {
        HDF_LOGE("%s: RegisterPanel failed", __func__);
        return HDF_FAILURE;
    }
    return HDF_SUCCESS;
}

struct HdfDriverEntry g_xxxxDevEntry = {
    .moduleVersion = 1,
    .moduleName = "LCD_XXXX",
    .Init = XXXInit,
};

HDF_INIT(g_xxxxDevEntry);

• Configure and load the panel driver. All device information about the product is defined in the //vendor/MyProductVendor/MyProduct/config/device_info/device_info.hcs file. Modify the file by adding configurations for the device named device_lcd to the host named display. Note: The value of moduleName must be the same as that in the panel driver.

root {
    ...
    display :: host {
        device_lcd :: device {
                deviceN :: deviceNode {
                    policy = 0;
                    priority = 100;
                    preload = 2;
                    moduleName = "LCD_XXXX";
                }
        }
    }
}

For details about driver development, see LCD.

2. Touchscreen

This section describes how to port a touchscreen driver. The touchscreen driver is stored in the //drivers/framework/model/input/driver/touchscreen directory. To port a touchscreen driver, register a ChipDevice model instance.

• Create a touchscreen driver.

Create the touch_ic_name.c file in the directory. Replace ic_name with the name of your chip. The file template is as follows:

#include "hdf_touch.h"

static int32_t HdfXXXXChipInit(struct HdfDeviceObject *device)
{
    ChipDevice *tpImpl = CreateXXXXTpImpl();
    if(RegisterChipDevice(tpImpl) != HDF_SUCCESS) {
        ReleaseXXXXTpImpl(tpImpl);
        return HDF_FAILURE;
    }
    return HDF_SUCCESS;
}

struct HdfDriverEntry g_touchXXXXChipEntry = {
    .moduleVersion = 1,
    .moduleName = "HDF_TOUCH_XXXX",
    .Init = HdfXXXXChipInit,
};

HDF_INIT(g_touchXXXXChipEntry);

Implement the following interfaces in ChipDevice:

• Configure the product and load the driver.

  All device information about the product is defined in the //vendor/MyProductVendor/MyProduct/config/device_info/device_info.hcs file. Modify the file by adding configurations for the device named device_touch_chip to the host named input. Note: The value of moduleName must be the same as that in the touchscreen driver.

                deviceN :: deviceNode {
                    policy = 0;
                    priority = 130;
                    preload = 0;
                    permission = 0660;
                    moduleName = "HDF_TOUCH_XXXX";
                    deviceMatchAttr = "touch_XXXX_configs";
                }

For details about driver development, see TOUCHSCREEN.

3. WLAN

The WLAN driver is divided into two parts. One of the parts manages WLAN devices, and the other part manages WLAN traffic. HDF WLAN provides abstraction for the two parts. Currently, only the WLAN with the SDIO interface is supported.

Figure 1 WLAN chip

To support a chip, implement a ChipDriver for it. The major task is to implement the following interfaces provided by HDF_WLAN_CORE and NetDevice.

To port a WLAN driver, perform the following steps:

1. Create an HDF driver. You are advised to place the code file in the //device/MySoCVendor/peripheral/wifi/chip_name/ directory. The file template is as follows:

static int32_t HdfWlanHisiChipDriverInit(struct HdfDeviceObject *device) {
    static struct HdfChipDriverFactory factory = CreateChipDriverFactory();
    struct HdfChipDriverManager *driverMgr = HdfWlanGetChipDriverMgr();
    if (driverMgr->RegChipDriver(&factory) != HDF_SUCCESS) {
        HDF_LOGE("%s fail: driverMgr is NULL!", __func__);
        return HDF_FAILURE;
    }
    return HDF_SUCCESS;
}

struct HdfDriverEntry g_hdfXXXChipEntry = {
    .moduleVersion = 1,
    .Init = HdfWlanXXXChipDriverInit,
    .Release = HdfWlanXXXChipRelease,
    .moduleName = "HDF_WIFI_CHIP_XXX"
};

HDF_INIT(g_hdfXXXChipEntry);

Create an HdfChipDriverFactory in the CreateChipDriverFactory. The interfaces are as follows:

Implement the following interfaces in the HdfChipDriver.

2. Compile the configuration file to describe the devices supported by the driver.

Create the chip configuration file //vendor/MyProductVendor/MyProduct/config/wifi/wlan_chip_chip_name.hcs in the product configuration directory.

Replace MyProductVendor, MyProduct, and chip_name in the path with the actual names.

The sample code is as follows:

root {
    wlan_config {
        chip_name :& chipList {
            chip_name :: chipInst {
                match_attr = "hdf_wlan_chips_chip_name"; /* Configure the matching attribute, which is used to provide the configuration root of the driver.*/
                driverName = "driverName"; /* The value must be the same as that of driverName in HdfChipDriverFactory.*/
                sdio {
                    vendorId = 0x0296;
                    deviceId = [0x5347];
                }
            }
        }
    }
}

3. Edit the configuration file and load the driver.

All device information about the product is defined in the //vendor/MyProductVendor/MyProduct/config/device_info/device_info.hcs file. Modify the file by adding configurations for the device named device_wlan_chips to the host named network. Note: The value of moduleName must be the same as that in the touchscreen driver.

                deviceN :: deviceNode {
                    policy = 0;
                    preload = 2;
                    moduleName = "HDF_WLAN_CHIPS";
                    deviceMatchAttr = "hdf_wlan_chips_chip_name";
                    serviceName = "driverName";
                }

4. Build the driver.

• Create a kernel configuration menu. Create a Kconfig file in the //device/MySoCVendor/peripheral directory. The file template is as follows:

config DRIVERS_WLAN_XXX
    bool "Enable XXX WLAN Host driver"
    default n
    depends on DRIVERS_HDF_WIFI
    help
      Answer Y to enable XXX Host driver. Support chip xxx

Add the following sample code to the end of the //drivers/adapter/khdf/linux/model/network/wifi/Kconfig file to add the configuration menu to the kernel:

source "../../../../../device/MySoCVendor/peripheral/Kconfig"

• Create a build script.

  Add the following configuration to the end of the //drivers/adapter/khdf/linux/model/network/wifi/Makefile file:

HDF_DEVICE_ROOT := $(HDF_DIR_PREFIX)/../device
obj-$(CONFIG_DRIVERS_WLAN_XXX) += $(HDF_DEVICE_ROOT)/MySoCVendor/peripheral/build/standard/

When DRIVERS_WLAN_XXX is enabled in the kernel, makefile in //device/MySoCVendor/peripheral/build/standard/ is called. For more details, see WLAN Development.

4. Samples

For details about the porting sample, see the DAYU development board adaptation guide.