一、背景
OpenHarmony系统移植最核心的步骤是内核的移植,内核的稳定是一切子系统稳定的基础,上一篇我们讲述了内核启动原理,以及vendor、board的开发配置,本文将介绍SoC层级的移植适配流程。
二、SoC适配
SoC配置芯片层级编译依赖库,包括CMSIS、HAL(硬件抽象层)等,这里包含操作总线、串口、时钟、寄存等库函数。
1.创建对应的文件目录结构
目录名称按照芯片厂家、芯片型号来创建,比如st公司下的stm32f4xx系列芯片。

配置文件内容如下:
2.移植HAL库函数等文件
对于STM32F407我们可以使用官方的STM32CubeMX生成对应的标准的hal库函数文件。
(1)选择ACCESS TO MCU SELECTOR

(2)勾选Arm Cortex-M4 --> STM32F4 --> STM32F407ZGTx

(3)填写工程名称,选择工程保存路径,选择Makefile作为编译工具,点击GENERATE CODE生成工程代码

(4)使用vscode打开目录,我们得到如下工程

回顾一下之前讲过的系统启动的流程:
(1)HAL初始化
(2)系统时钟初始化
(3)系统初始化
(4)系统启动
接下来我们将HAL库函数文件及芯片头文件迁移到OH代码中,文件路径如下:

将Drivers中的CMSIS、STM32F4xx_HAL_Driver复制到/device/soc/st/stm32f4xx/sdk/Drivers中

3.修改系统编译配置文件
使用OH的gn以及config文件配置系统编译流程以及包依赖关系,涉及到的配置文件如下:
device/board/alientek/explorer/liteos_m/config.gni# Kernel type, e.g. "linux", "liteos_a", "liteos_m".kernel_type = "liteos_m"# Kernel version.kernel_version = "3.0.0"# Board CPU type, e.g. "cortex-a7", "riscv32".board_cpu = "cortex-m4"# Board arch, e.g. "armv7-a", "rv32imac".board_arch = ""# Toolchain name used for system compiling.# E.g. gcc-arm-none-eabi, arm-linux-harmonyeabi-gcc, ohos-clang, riscv32-unknown-elf.# Note: The default toolchain is "ohos-clang". It's not mandatory if you use the default toolchain.board_toolchain = "arm-none-eabi-gcc"use_board_toolchain = true# The toolchain path installed, it's not mandatory if you have added toolchain path to your ~/.bashrc.board_toolchain_path = ""# Compiler prefix.board_toolchain_prefix = "arm-none-eabi-"# Compiler type, "gcc" or "clang".board_toolchain_type = "gcc"#Debug compiler optimization level optionsboard_opt_flags = ["-mcpu=cortex-m4","-mthumb","-mfpu=fpv4-sp-d16","-mfloat-abi=hard",]# Board related common compile flags.board_cflags = ["-Og","-Wall","-fdata-sections","-ffunction-sections","-DSTM32F407xx","-DHAL_UART_MODULE_ENABLED"]board_cflags += board_opt_flagsboard_asmflags = ["-Og","-Wall","-fdata-sections","-ffunction-sections",]board_asmflags += board_opt_flagsboard_cxx_flags = board_cflagsboard_ld_flags = ["-T${ohos_root_path}device/board/alientek/explorer/liteos_m/STM32F407ZGTx_FLASH.ld"]board_ld_flags += board_opt_flags# Board related headfiles search path.board_include_dirs = [ "//utils/native/lite/include" ]# Board adapter dir for OHOS components.board_adapter_dir = ""这里的核心工作就是将原有的Makefile编译文件翻译成OH的config.gni,可以看到有很多的编译参数以及宏变量定义。修改编译依赖文件BUILD.gndevice/board/alientek/explorer/liteos_m/BUILD.gnimport("//kernel/liteos_m/liteos.gni")module_name = get_path_info(rebase_path("."), "name")kernel_module(module_name) {sources = ["startup_stm32f407xx.s","Src/main.c","Src/delay.c","Src/led.c","Src/sys.c","Src/usart.c","Src/stm32f4xx_hal_msp.c","Src/stm32f4xx_it.c","Src/system_stm32f4xx.c",]include_dirs = [ "Inc",]}# "-Wl,-T" + rebase_path("STM32F407ZGTx_FLASH.ld"),config("public") {ldflags = ["-Wl,-u_printf_float"]libs = ["c","m","nosys",]}device/soc/st/stm32f4xx/sdk/BUILD.gnimport("//kernel/liteos_m/liteos.gni")module_name = "stm32f4xx_sdk"kernel_module(module_name) {asmflags = board_asmflagssources = ["Drivers/STM32F4xx_HAL_Driver/Src/stm32f4xx_hal_rcc.c","Drivers/STM32F4xx_HAL_Driver/Src/stm32f4xx_hal_rcc_ex.c","Drivers/STM32F4xx_HAL_Driver/Src/stm32f4xx_hal_gpio.c","Drivers/STM32F4xx_HAL_Driver/Src/stm32f4xx_hal_dma_ex.c","Drivers/STM32F4xx_HAL_Driver/Src/stm32f4xx_hal_dma.c","Drivers/STM32F4xx_HAL_Driver/Src/stm32f4xx_hal_cortex.c","Drivers/STM32F4xx_HAL_Driver/Src/stm32f4xx_hal.c","Drivers/STM32F4xx_HAL_Driver/Src/stm32f4xx_hal_exti.c","Drivers/STM32F4xx_HAL_Driver/Src/stm32f4xx_hal_uart.c",]include_dirs = ["//device/board/alientek/explorer/liteos_m/Inc"]}#指定全局头文件搜索路径config("public") {include_dirs = ["Drivers/STM32F4xx_HAL_Driver/Inc","Drivers/CMSIS/Device/ST/STM32F4xx/Include",]}
4.改造main函数,拉起系统内核
我们对device/board/alientek/explorer/liteos_m/Src/main.c文件进行如下编辑。
三、编译与烧录
使用hb工具进行编译,hb set选择编译目标,hb build -f执行编译。

日志输出explorer build success表示编译成功。
编译过程中可能会遇到缺少某些结构体或者函数的定义,需要细心排查,注意宏定义是否打开。
STM32F407开发板支持串口和ST-LINK烧录方式,但OH编译出来的是bin文件,bin无法直接通过串口烧录。需要用到ST-LINK工具进行烧录,烧录时需要指定flash,开始地址:0x08000000,大小:0x100000。

开始烧录

点亮开发板

四、总结
本文主要讲述了OpenHarmony内核的SoC代码移植。因为STM32F407的架构和基础SDK都是官方开源的,所以移植工作也较为容易,但在实际工作中如果遇到未开源的芯片,那么需要模组或芯片厂商提供技术支持才可完成移植工作。到这里瘦设备OH适配的最核心工作已完成,希望能对热爱OpenHarmony的小伙伴有所帮助。
希望未来能有更多芯片厂商开源架构吧
开发的工具可以分享下吗
学习下适配过程
感谢做移植工作老师!
可以去对应官方下找