OpenHarmony瘦設(shè)備內(nèi)核移植實(shí)戰(zhàn)（三）
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一、背景
OpenHarmony系統(tǒng)移植最核心的步驟是內(nèi)核的移植，內(nèi)核的穩(wěn)定是一切子系統(tǒng)穩(wěn)定的基礎(chǔ)，上一篇我們講述了內(nèi)核啟動(dòng)原理，以及vendor、board的開(kāi)發(fā)配置，本文將介紹SoC層級(jí)的移植適配流程。
二、SoC適配
SoC配置芯片層級(jí)編譯依賴庫(kù)，包括CMSIS、HAL（硬件抽象層）等，這里包含操作總線、串口、時(shí)鐘、寄存等庫(kù)函數(shù)。
1、創(chuàng)建對(duì)應(yīng)的文件目錄結(jié)構(gòu)
目錄名稱按照芯片廠家、芯片型號(hào)來(lái)創(chuàng)建，比如st公司下的stm32f4xx系列芯片。
配置文件內(nèi)容如下：
device/soc/st/stm32f4xx/Kconfig.liteos_m.defconfig.series
if SOC_SERIES_STM32F4xx
rsource "Kconfig.liteos_m.defconfig.stm32f4xx"
config SOC_SERIES
string
default "stm32f4xx"
endif
device/soc/st/stm32f4xx/Kconfig.liteos_m.defconfig.stm32f4xx
config SOC
string
default "stm32f4xx"
depends on SOC_STM32F4xx
device/soc/st/stm32f4xx/Kconfig.liteos_m.series
config SOC_SERIES_STM32F4xx
bool "STMicroelectronics STM32F4xx series"
select ARCH_ARM
select SOC_COMPANY_STMICROELECTRONICS
select CPU_CORTEX_M4
help
Enable support for STMicroelectronics STM32F4xx series
device/soc/st/stm32f4xx/Kconfig.liteos_m.soc
choice
prompt "STMicroelectronics STM32F4xx series SoC"
depends on SOC_SERIES_STM32F4xx
config SOC_STM32F407
bool "SoC STM32F407"
Endchoice
device/soc/st/Kconfig.liteos_m.defconfig
rsource "*/Kconfig.liteos_m.defconfig.series"
device/soc/st/Kconfig.liteos_m.defconfig
rsource "*/Kconfig.liteos_m.series"
device/soc/st/Kconfig.liteos_m.soc
config SOC_COMPANY_STMICROELECTRONICS
bool
if SOC_COMPANY_STMICROELECTRONICS
config SOC_COMPANY
default "st"
rsource "*/Kconfig.liteos_m.soc"
endif # SOC_COMPANY_STMICROELECTRONICS
device/soc/st/BUILD.gn
if (ohos_kernel_type == "liteos_m") {
import("http://kernel/liteos_m/liteos.gni")
module_name = get_path_info(rebase_path("."), "name")
module_group(module_name) {
modules = [ "stm32f4xx" ]
}
}
device/soc/st/stm32f4xx/BUILD.gn
if (ohos_kernel_type == "liteos_m") {
import("http://kernel/liteos_m/liteos.gni")
module_name = get_path_info(rebase_path("."), "name")
module_group(module_name) {
modules = [ "liteos_m", "sdk" ]
}
}2、移植HAL庫(kù)函數(shù)等文件
對(duì)于STM32F407我們可以使用官方的STM32CubeMX生成對(duì)應(yīng)的標(biāo)準(zhǔn)的hal庫(kù)函數(shù)文件。
（1）選擇ACCESS TO MCU SELECTOR。
（2）勾選Arm Cortex-M4 --> STM32F4 --> STM32F407ZGTx。
（3）填寫(xiě)工程名稱，選擇工程保存路徑，選擇Makefile作為編譯工具，點(diǎn)擊GENERATE CODE生成工程代碼。
（4）使用vscode打開(kāi)目錄，我們得到如下工程。
回顧一下之前講過(guò)的系統(tǒng)啟動(dòng)的流程：
- HAL初始化
- 系統(tǒng)時(shí)鐘初始化
- 系統(tǒng)初始化
- 系統(tǒng)啟動(dòng)
接下來(lái)我們將HAL庫(kù)函數(shù)文件及芯片頭文件遷移到OH代碼中，文件路徑如下：
將Drivers中的CMSIS、STM32F4xx_HAL_Driver復(fù)制到/device/soc/st/stm32f4xx/sdk/Drivers中。
3、修改系統(tǒng)編譯配置文件
使用OH的gn以及config文件配置系統(tǒng)編譯流程以及包依賴關(guān)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 = [ "http://utils/native/lite/include" ]# Board adapter dir for OHOS components.board_adapter_dir = ""這里的核心工作就是將原有的Makefile編譯文件翻譯成OH的config.gni，可以看到有很多的編譯參數(shù)以及宏變量定義。修改編譯依賴文件BUILD.gndevice/board/alientek/explorer/liteos_m/BUILD.gnimport("http://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("http://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 = ["http://device/board/alientek/explorer/liteos_m/Inc"]}#指定全局頭文件搜索路徑config("public") {include_dirs = ["Drivers/STM32F4xx_HAL_Driver/Inc","Drivers/CMSIS/Device/ST/STM32F4xx/Include",]}4、改造main函數(shù)，拉起系統(tǒng)內(nèi)核
我們對(duì)device/board/alientek/explorer/liteos_m/Src/main.c文件進(jìn)行如下編輯。
int main(void)
{
HAL_Init(); /* 初始化HAL庫(kù) */
sys_stm32_clock_init(336, 8, 2, 7); /* 初始化時(shí)鐘頻率168Mhz */
delay_init(168); /* 延時(shí)初始化 */
printf("hal、系統(tǒng)始終初始化完畢，開(kāi)始啟動(dòng)系統(tǒng)...\n");
RunTask();
}
void RunTask()
{
unsigned int ret;
ret = LOS_KernelInit(); // 初始化LiteOS系統(tǒng)
if (ret != LOS_OK)
{
printf("Liteos kernel init failed! ERROR: 0x%x\n", ret);
}
else
{
LOS_Start(); // 啟動(dòng)系統(tǒng)
}
...
}三、編譯與燒錄
使用hb工具進(jìn)行編譯，hb set選擇編譯目標(biāo)，hb build -f執(zhí)行編譯。
日志輸出explorer build success表示編譯成功。
編譯過(guò)程中可能會(huì)遇到缺少某些結(jié)構(gòu)體或者函數(shù)的定義，需要細(xì)心排查，注意宏定義是否打開(kāi)。
STM32F407開(kāi)發(fā)板支持串口和ST-LINK燒錄方式，但OH編譯出來(lái)的是bin文件，bin無(wú)法直接通過(guò)串口燒錄。需要用到ST-LINK工具進(jìn)行燒錄，燒錄時(shí)需要指定flash，開(kāi)始地址：0x08000000，大?。?x100000。
開(kāi)始燒錄
點(diǎn)亮開(kāi)發(fā)板
四、總結(jié)
本文主要講述了OpenHarmony內(nèi)核的SoC代碼移植。因?yàn)镾TM32F407的架構(gòu)和基礎(chǔ)SDK都是官方開(kāi)源的，所以移植工作也較為容易，但在實(shí)際工作中如果遇到未開(kāi)源的芯片，那么需要模組或芯片廠商提供技術(shù)支持才可完成移植工作。到這里瘦設(shè)備OH適配的最核心工作已完成，希望能對(duì)熱愛(ài)OpenHarmony的小伙伴有所幫助。
