小熊派：用OpenHarmory3.0点亮LED

摘要：作为一个代表性的完整的开发，本案例可以分成3大部分：代码文件的规划，LED灯的驱动开发，点亮LED的业务开发。

本文分享自华为云社区《在小熊派Micro上用OpenHarmory3.0点亮LED(1)LED驱动开发》，作者：神龙居市。

项目总览

作为一个代表性的完整的开发，本案例可以分成3大部分：代码文件的规划，LED灯的驱动开发，点亮LED的业务开发。

一、LED驱动开发

1.1.确定目录结构

1.1.1.根据HDF框架以组件化的驱动模型作为核心设计思路，HDF框架将一类设备驱动放在同一个host里面，开发者也可以将驱动功能分层独立开发和部署，支持一个驱动多个node，HDF驱动模型如下图

1.1.2.本案例目录

在./device/st/drivers路径下新建一个led的目录，用来存放驱动源码文件。

在./device/st/bearpi_hm_micro/liteos_a/hdf_config路径下新建led文件夹，并创建驱动配置文件led_config.hcs

1.2.LED驱动实现

1.2.1.驱动实现包含驱动业务代码和驱动入口注册，在led.c文件中添加以下代码

#include "hdf_device_desc.h"
#include "hdf_log.h"
#include "device_resource_if.h"
#include "osal_io.h"
#include "osal.h"
#include "osal_mem.h"
#include "gpio_if.h"#define HDF_LOG_TAG led_driver // 打印日志所包含的标签，如果不定义则用默认定义的HDF_TAG标签
#define LED_WRITE_READ 1       // 读写操作码1enum LedOps {LED_OFF,LED_ON,  LED_TOGGLE,
};struct Stm32Mp1ILed {uint32_t gpioNum;
};
static struct Stm32Mp1ILed g_Stm32Mp1ILed;
uint8_t status = 0;
// Dispatch是用来处理用户态发下来的消息
int32_t LedDriverDispatch(struct HdfDeviceIoClient *client, int cmdCode, struct HdfSBuf *data, struct HdfSBuf *reply)
{uint8_t contrl;HDF_LOGE("Led driver dispatch");if (client == NULL || client->device == NULL){HDF_LOGE("Led driver device is NULL");return HDF_ERR_INVALID_OBJECT;}switch (cmdCode){/* 接收到用户态发来的LED_WRITE_READ命令 */case LED_WRITE_READ:/* 读取data里的数据，赋值给contrl */HdfSbufReadUint8(data,&contrl);                  switch (contrl){/* 开灯 */case LED_ON:                                            GpioWrite(g_Stm32Mp1ILed.gpioNum, GPIO_VAL_LOW);status = 1;break;/* 关灯 */case LED_OFF:                                           GpioWrite(g_Stm32Mp1ILed.gpioNum, GPIO_VAL_HIGH);status = 0;break;/* 状态翻转 */case LED_TOGGLE:if(status == 0){GpioWrite(g_Stm32Mp1ILed.gpioNum, GPIO_VAL_LOW);status = 1;}else{GpioWrite(g_Stm32Mp1ILed.gpioNum, GPIO_VAL_HIGH);status = 0;}                                        break;default:break;}/* 把LED的状态值写入reply, 可被带至用户程序 */if (!HdfSbufWriteInt32(reply, status))                {HDF_LOGE("replay is fail");return HDF_FAILURE;}break;default:break;}return HDF_SUCCESS;
}// 读取驱动私有配置
static int32_t Stm32LedReadDrs(struct Stm32Mp1ILed *led, const struct DeviceResourceNode *node)
{int32_t ret;struct DeviceResourceIface *drsOps = NULL;drsOps = DeviceResourceGetIfaceInstance(HDF_CONFIG_SOURCE);if (drsOps == NULL || drsOps->GetUint32 == NULL) {HDF_LOGE("%s: invalid drs ops!", __func__);return HDF_FAILURE;}/* 读取led.hcs里面led_gpio_num的值 */ret = drsOps->GetUint32(node, "led_gpio_num", &led->gpioNum, 0); if (ret != HDF_SUCCESS) {HDF_LOGE("%s: read led gpio num fail!", __func__);return ret;}return HDF_SUCCESS;
}//驱动对外提供的服务能力，将相关的服务接口绑定到HDF框架
int32_t HdfLedDriverBind(struct HdfDeviceObject *deviceObject)
{if (deviceObject == NULL){HDF_LOGE("Led driver bind failed!");return HDF_ERR_INVALID_OBJECT;}static struct IDeviceIoService ledDriver = {.Dispatch = LedDriverDispatch,};deviceObject->service = (struct IDeviceIoService *)(&ledDriver);HDF_LOGD("Led driver bind success");return HDF_SUCCESS;
}// 驱动自身业务初始的接口
int32_t HdfLedDriverInit(struct HdfDeviceObject *device)
{struct Stm32Mp1ILed *led = &g_Stm32Mp1ILed;int32_t ret;if (device == NULL || device->property == NULL) {HDF_LOGE("%s: device or property NULL!", __func__);return HDF_ERR_INVALID_OBJECT;}/* 读取hcs私有属性值 */ret = Stm32LedReadDrs(led, device->property);if (ret != HDF_SUCCESS) {HDF_LOGE("%s: get led device resource fail:%d", __func__, ret);return ret;}/* 将GPIO管脚配置为输出 */ret = GpioSetDir(led->gpioNum, GPIO_DIR_OUT);if (ret != 0){HDF_LOGE("GpioSerDir: failed, ret %d\n", ret);return ret;}HDF_LOGD("Led driver Init success");return HDF_SUCCESS;
}// 驱动资源释放的接口
void HdfLedDriverRelease(struct HdfDeviceObject *deviceObject)
{if (deviceObject == NULL){HDF_LOGE("Led driver release failed!");return;}HDF_LOGD("Led driver release success");return;
}// 定义驱动入口的对象，必须为HdfDriverEntry（在hdf_device_desc.h中定义）类型的全局变量
struct HdfDriverEntry g_ledDriverEntry = {.moduleVersion = 1,.moduleName = "HDF_LED",.Bind = HdfLedDriverBind,.Init = HdfLedDriverInit,.Release = HdfLedDriverRelease,
};// 调用HDF_INIT将驱动入口注册到HDF框架中
HDF_INIT(g_ledDriverEntry);

1.2.2.编译脚本文件

在led/BUILD.gn文件中添加以下代码，将led.c编译成hdf_led

import("//drivers/adapter/khdf/liteos/hdf.gni")
hdf_driver("hdf_led") {sources = ["led.c",]
}

在/device/st/drivers/BUILD.gn文件中添加以下代码，将hdf_led编译进内核，"led"是新增内容

1.3.驱动配置

HDF使用HCS作为配置描述源码，驱动配置包含两部分，HDF框架定义的驱动设备描述和驱动的私有配置信息。

HDF框架加载驱动所需要的信息来源于HDF框架定义的驱动设备描述，因此基于HDF框架开发的驱动必须要在HDF框架定义的device_info.hcs配置文件中添加对应的设备描述，所以我们需要在device\st\bearpi_hm_micro\liteos_a\hdf_config\device_info\device_info.hcs中添加LED设备描述

device_led :: device {             // led设备节点device0 :: deviceNode {        // led驱动的DeviceNode节点policy = 2;                // policy字段是驱动服务发布的策略，在驱动服务管理章节有详细介绍priority = 10;             // 驱动启动优先级（0-200），值越大优先级越低，建议默认配100，优先级相同则不保证device的加载顺序preload = 1;               // 驱动按需加载字段permission = 0777;         // 驱动创建设备节点权限moduleName = "HDF_LED";    // 驱动名称，该字段的值必须和驱动入口结构的moduleName值一致serviceName = "hdf_led";   // 驱动对外发布服务的名称，必须唯一deviceMatchAttr = "st_stm32mp157_led"; // 驱动私有数据匹配的关键字，必须和驱动私有数据配置表中的match_attr值相等}
}

1.4.私有驱动信息配置

如果驱动有私有配置，则可以添加一个驱动的配置文件，用来填写一些驱动的默认配置信息，HDF框架在加载驱动的时候，会将对应的配置信息获取并保存在HdfDeviceObject 中的property里面，通过Bind和Init传递给驱动，所以我们需要在device\st\bearpi_hm_micro\liteos_a\hdf_config\led\led_config.hcs中添加LED私有配置描述。

root {LedDriverConfig {led_gpio_num = 13;match_attr = "st_stm32mp157_led";   //该字段的值必须和device_info.hcs中的deviceMatchAttr值一致}
}

1.5.板级配置入口文件

配置信息定义之后，需要将该配置文件添加到板级配置入口文件device\st\bearpi_hm_micro\liteos_a\hdf_config\hdf.hcs

#include "device_info/device_info.hcs"
#include "led/led_config.hcs"

二、点亮LED业务代码

2.1.创建目录

编写业务时，务必先在./applications/BearPi/BearPi-HM_Micro/samples路径下新建一个目录（或一套目录结构），用于存放业务源码文件.

在samples文件夹下增加my_led_app文件夹，并新建BUILD.gn和my_led_app.c两个文件

2.2.编写业务代码

在my_led_app.c中添加以下业务代码

#include <fcntl.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdio.h>
#include "hdf_sbuf.h"
#include "hdf_io_service_if.h"#define LED_WRITE_READ 1
#define LED_SERVICE "hdf_led"static int SendEvent(struct HdfIoService *serv, uint8_t eventData)
{int ret = 0;struct HdfSBuf *data = HdfSBufObtainDefaultSize();if (data == NULL){printf("fail to obtain sbuf data!\r\n");return 1;}struct HdfSBuf *reply = HdfSBufObtainDefaultSize();if (reply == NULL){printf("fail to obtain sbuf reply!\r\n");ret = HDF_DEV_ERR_NO_MEMORY;goto out;}/* 写入数据 */if (!HdfSbufWriteUint8(data, eventData)){printf("fail to write sbuf!\r\n");ret = HDF_FAILURE;goto out;}/* 通过Dispatch发送到驱动 */ret = serv->dispatcher->Dispatch(&serv->object, LED_WRITE_READ, data, reply);if (ret != HDF_SUCCESS){printf("fail to send service call!\r\n");goto out;}int replyData = 0;/* 读取驱动的回复数据 */if (!HdfSbufReadInt32(reply, &replyData)){printf("fail to get service call reply!\r\n");ret = HDF_ERR_INVALID_OBJECT;goto out;}printf("\r\nGet reply is: %d\r\n", replyData);
out:HdfSBufRecycle(data);HdfSBufRecycle(reply);return ret;
}int main(int argc, char **argv)
{int i;/* 获取服务 */struct HdfIoService *serv = HdfIoServiceBind(LED_SERVICE);if (serv == NULL){printf("fail to get service %s!\r\n", LED_SERVICE);return HDF_FAILURE;}for (i=0; i < argc; i++){printf("\r\nArgument %d is %s.\r\n", i, argv[i]);}SendEvent(serv, atoi(argv[1]));HdfIoServiceRecycle(serv);printf("exit");return HDF_SUCCESS;
}

2.3.编写将构建业务代码的BUILD.gn文件

BUILD.gn文件由三部分内容（目标、源文件、头文件路径）构成，需由开发者完成填写。以my_led_app为例，需要创建./applications/BearPi/BearPi-HM_Micro/samples/my_led_app/BUILD.gn，并完如下配置

import("//build/lite/config/component/lite_component.gni")HDF_FRAMEWORKS = "//drivers/framework"executable("led_lib") {output_name = "my_led"sources = ["my_led_app.c",]include_dirs = ["$HDF_FRAMEWORKS/ability/sbuf/include","$HDF_FRAMEWORKS/core/shared/include","$HDF_FRAMEWORKS/core/host/include","$HDF_FRAMEWORKS/core/master/include","$HDF_FRAMEWORKS/include/core","$HDF_FRAMEWORKS/include/utils","$HDF_FRAMEWORKS/utils/include","$HDF_FRAMEWORKS/include/osal","//drivers/adapter/uhdf/posix/include","//third_party/bounds_checking_function/include","//base/hiviewdfx/hilog_lite/interfaces/native/innerkits",]deps = ["//base/hiviewdfx/hilog_lite/frameworks/featured:hilog_shared","//drivers/adapter/uhdf/manager:hdf_core","//drivers/adapter/uhdf/posix:hdf_posix_osal",]
}lite_component("my_led_app") {features = [":led_lib",]
}

首先导入 gni 组件，将源码my_led_app.c编译成led_lib库文件
输出的可执行文件名称由 output_name 定义为my_led
include_dirs 里面加入my_led_app.c里面需要用到的.h的头文件路径
deps 里面加入所依赖的库。
然后将led_lib打包成 lite_component，命名为my_led_app组件。

2.4.添加新组件

修改文件build/lite/components/applications.json，添加组件my_sample的配置

{"component": "my_sample","description": "my samples","optional": "true","dirs": ["applications/BearPi/BearPi-HM_Micro/samples/my_first_app","applications/BearPi/BearPi-HM_Micro/samples/my_led_app"],"targets": ["//applications/BearPi/BearPi-HM_Micro/samples/my_first_app:my_app","//applications/BearPi/BearPi-HM_Micro/samples/my_led_app:my_led_app"],"rom": "","ram": "","output": [],"adapted_kernel": [ "liteos_a" ],"features": [],"deps": {"components": [],"third_party": [ ]}},

2.5.修改单板配置文件

修改文件vendor/bearpi/bearpi_hm_micro/config.json，新增my_sample组件的条目

{"subsystem": "applications","components": [{ "component": "my_sample", "features":[] },{ "component": "bearpi_sample_app", "features":[] },{ "component": "bearpi_screensaver_app", "features":[] }]
},

三、编译

在项目根目录下执行hb set 设置开发板，只有一个，回车即可

执行编译命令

hb build -t notest --tee -f

等待编译完成后，屏幕出现：build success字样，说明编译成功。

当编译完后，可以直接查看到最终编译的固件，具体路径在： \project\bearpi-hm_micro_small\out\bearpi-hm_micro\bearpi-hm_micro

文件夹结构说明

OHOS_Image.stm32：系统镜像文件
rootfs_vfat.img：根文件系统
userfs_vfat.img：用户文件系统

执行以下三条指令将以上三个文件复制到applications/BearPi/BearPi-HM_Micro/tools/download_img/kernel/下，以便后续烧录系统使用

cp out/bearpi_hm_micro/bearpi_hm_micro/OHOS_Image.stm32 applications/BearPi/BearPi-HM_Micro/tools/download_img/kernel/
cp out/bearpi_hm_micro/bearpi_hm_micro/rootfs_vfat.img applications/BearPi/BearPi-HM_Micro/tools/download_img/kernel/
cp out/bearpi_hm_micro/bearpi_hm_micro/userfs_vfat.img applications/BearPi/BearPi-HM_Micro/tools/download_img/kernel/

四、总结

至此，完整的项目工程就开发好了，下一步就是烧录和运行了。

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