OpenHarmony：如何使用HDF驱动控制LED灯

一、程序简介

该程序是基于OpenHarmony标准系统编写的基础外设类：RGB LED。

目前已在凌蒙派-RK3568开发板跑通。详细资料请参考官网：https://gitee.com/Lockzhiner-Electronics/lockzhiner-rk3568-openharmony/tree/master/samples/b02_hdf_rgb_led。

详细资料请参考OpenHarmony官网：

• GPIO平台驱动开发
• GPIO应用程序开发

二、硬件设计

RGB LED灯整体硬件电路如下图所示,硬件电路中包含了三个GPIO控制管脚控制RGB　LED灯，低电平点亮LED灯，高电平熄灭LED灯。电路简单，这边不对此进行多余的说明。

三、程序解析

1、目录结构

b02_hdf_rgb_led
├── config              # HDF资源配置文件目录
    ├── config.hcs      # 接口IO配置文件
    ├── device_info.hcs # 设备信息配置文件
├── drivers             # 内核HDF驱动程序目录
    ├── rgb_led_drv.c   # 内核HDF驱动程序
    ├── Makefile        # 内核HDF驱动编译脚本
├── figures             # MD文档图片
├── BUILD.gn            # GN文件
├── rgb_led.c           # 应用层控制程序

2、内核HDF驱动程序

（1）接口函数

• 函数名：HdfRgbLedDriverInit.
• 功能说明：HDF初始化注册，读取HDF资源配置文件，获取三色灯控制GPIO管脚。

int32_t HdfRgbLedDriverInit(struct HdfDeviceObject *deviceObject)
{
    if (deviceObject == NULL) {
        HDF_LOGE("g_rgbLedDriverEntry: %s fAIled", __func__);
        return HDF_ERR_INVALID_OBJECT;
    }
    struct DeviceResourceIface *CfgOps = NULL;
    CfgOps = DeviceResourceGetIfaceInstance(HDF_CONFIG_SOURCE);
    if (CfgOps == NULL || CfgOps->GetUint32 == NULL) {
        HDF_LOGE("%s: DeviceResourceGetIfaceInstance failed", __func__);
        return HDF_FAILURE;
    }
    if (CfgOps->GetUint32(deviceObject->property, "rgb_led_version", &g_rgbLedCfg.rgb_led_version, 0) != HDF_SUCCESS) {
        HDF_LOGE("%s: read rgb_led_version failed", __func__);
        return HDF_FAILURE;
    }
    if (CfgOps->GetUint32(deviceObject->property, "rgb_led_red", &g_rgbLedCfg.rgb_led_red, 0) != HDF_SUCCESS) {
        g_rgbLedCfg.rgb_led_version = 0;
        HDF_LOGE("%s: read rgb_led_red failed", __func__);
        return HDF_FAILURE;
    }
    if (CfgOps->GetUint32(deviceObject->property, "rgb_led_green", &g_rgbLedCfg.rgb_led_green, 0) != HDF_SUCCESS) {
        g_rgbLedCfg.rgb_led_version = 0;
        HDF_LOGE("%s: read rgb_led_green failed", __func__);
        return HDF_FAILURE;
    }
    if (CfgOps->GetUint32(deviceObject->property, "rgb_led_blue", &g_rgbLedCfg.rgb_led_blue, 0) != HDF_SUCCESS) {
        g_rgbLedCfg.rgb_led_version = 0;
        HDF_LOGE("%s: read rgb_led_blue failed", __func__);
        return HDF_FAILURE;
    }
    HDF_LOGI("g_rgbLedDriverEntry: %s success", __func__);
    return HDF_SUCCESS;
}

• 函数名：HdfRgbLedDriverRelease。
• 功能说明：HDF去注册。

void HdfRgbLedDriverRelease(struct HdfDeviceObject *deviceObject)
{
    if (deviceObject == NULL) {
        HDF_LOGE("g_rgbLedDriverEntry: %s failed", __func__);
        return;
    }
    HDF_LOGI("g_rgbLedDriverEntry: %s success", __func__);
    return;
}

• 函数名：HdfRgbLedDriverBind。
• 功能说明：HDF绑定解析函数。

int32_t HdfRgbLedDriverBind(struct HdfDeviceObject *deviceObject)
{
    if (deviceObject == NULL) {
        HDF_LOGE("g_rgbLedDriverEntry: %s failed", __func__);
        return HDF_ERR_INVALID_OBJECT;
    }
    static struct IDeviceIOService ledDriverServ = {
        .Dispatch = rgbLedDriverDispatch,
    };
    deviceObject->service = (struct IDeviceIoService *)(&ledDriverServ);
    HDF_LOGI("g_rgbLedDriverEntry: %s success NodeName[%s]", __func__,
        deviceObject->property->name);
    return HDF_SUCCESS;
}

• 函数名：rgbLedDriverDispatch。
• 功能说明：解析函数，解析应用层下发的命令，执行命令对应操作，RGB_LED_WRITE控制三色灯亮灭。

int32_t rgbLedDriverDispatch(struct HdfDeviceIoClient *client, int32_t cmdId,
    struct HdfSBuf *dataBuf, struct HdfSBuf *replyBuf)
{
    int32_t result = HDF_FAILURE;
    int32_t rgbLedMode = 0;

    if (client == NULL || client->device == NULL) {
        HDF_LOGE("driver device is NULL");
        return HDF_ERR_INVALID_OBJECT;
    }
    if (g_rgbLedCfg.rgb_led_version != RGB_LED_VERSION) {
        HDF_LOGE("driver rgb_led_version not match");
        return HDF_FAILURE;
    }
    switch (cmdId) {
        case RGB_LED_WRITE:
            result = HdfSbufReadInt32(dataBuf, &rgbLedMode);
            if (result) {
                HDF_LOGI("%s: mode:[0x%X][%s%s%s]", __func__, rgbLedMode,
                    (rgbLedMode&RGB_LED_RED_BIT)?"R":"-",
                    (rgbLedMode&RGB_LED_GREEN_BIT)?"G":"-",
                    (rgbLedMode&RGB_LED_BLUE_BIT)?"B":"-");

                LedGpioCtrl(g_rgbLedCfg.rgb_led_red, (rgbLedMode&RGB_LED_RED_BIT)?LED_ON:LED_OFF);
                LedGpioCtrl(g_rgbLedCfg.rgb_led_green, (rgbLedMode&RGB_LED_GREEN_BIT)?LED_ON:LED_OFF);
                LedGpioCtrl(g_rgbLedCfg.rgb_led_blue, (rgbLedMode&RGB_LED_BLUE_BIT)?LED_ON:LED_OFF);
            }
            break;
        default:
            HDF_LOGE("%s: receiving unknown command", __func__);
            break;
    }
    return result;
}

• 函数名：LedGpioCtrl。
• 功能说明：LED GPIO控制函数，低电平点亮LED，高电平熄灭LED。

static int32_t LedGpioCtrl(uint16_t gpio, int32_t mode)
{
    uint16_t level = GPIO_VAL_HIGH;

    if (HDF_SUCCESS != GpioSetDir(gpio, GPIO_DIR_OUT)) {
        HDF_LOGE("%s: GpioSetDir failed", __func__);
        return HDF_FAILURE;
    }

    if (mode == LED_ON) {
        level = GPIO_VAL_LOW;
    } else if (mode == LED_OFF) {
        level = GPIO_VAL_HIGH;
    }

    if (HDF_SUCCESS != GpioWrite(gpio, level)) {
        HDF_LOGE("%s: GpioWrite failed", __func__);
        return HDF_FAILURE;
    }
    return HDF_SUCCESS;
}

3、应用层程序

（1）应用层代码分析

程序启动后获取命令行参数，如果命令行不带参数，RGB三色灯运行跑马灯；如果命令行带参数，根据传入的参数的低三位映射点亮对应的红灯、绿灯和蓝灯；通过HdfIoServiceBind绑定RGB三色灯HDF服务，获取HDF空间缓冲区，向缓冲区写入需要控制的RGB三色灯低三位数据，通过RGB_LED_WRITE命令下发到HDF驱动中，从而控制RGB三色灯亮灭。程序运行结束，回收HDF空间缓冲区和HDF服务。

int main(int argc, char* argv[])
{
    int ret = HDF_SUCCESS;
    int32_t mode = -1;
    if (argc == ARGS_NUM) {
        mode = atoi(argv[1]);
        /*low-3bits*/
        mode &= 0x7;
        HILOG_INFO(LOG_App, "[%s] main enter: mode[%s%s%s][0x%X]",
            LOG_TAG,
            (mode&RGB_LED_BLUE_BIT)?"B":"-",
            (mode&RGB_LED_GREEN_BIT)?"G":"-",
            (mode&RGB_LED_RED_BIT)?"R":"-",
            mode);
        printf("RGB mode[%s%s%s][0x%X]n",
            (mode&RGB_LED_BLUE_BIT)?"B":"-",
            (mode&RGB_LED_GREEN_BIT)?"G":"-",
            (mode&RGB_LED_RED_BIT)?"R":"-",
            mode);
    } else {
        HILOG_INFO(LOG_APP, "[%s] main enter: auto test RGB LED", LOG_TAG);
        printf("auto test RGB LEDn");
    }

    struct HdfIoService *serv = HdfIoServiceBind(RGB_LED_SERVICE_NAME);
    if (serv == NULL) {
        HILOG_ERROR(LOG_APP, "get service %s failed", RGB_LED_SERVICE_NAME);
        return -1;
    }
    struct HdfSBuf *data = HdfSbufObtainDefaultSize();
    if (data == NULL) {
        HILOG_ERROR(LOG_APP, "obtain data failed");
        return -1;
    }

    if (mode == -1) {
        mode = 0x8;
        while (mode) {
            HdfSbufFlush(data);
            if (!HdfSbufWriteInt32(data, --mode)) {
                HILOG_ERROR(LOG_APP, "write data failed");
                return -1;
            }
            ret = serv->dispatcher->Dispatch(&serv->object, RGB_LED_WRITE, data, NULL);
            sleep(1);
        }
    } else {
        if (!HdfSbufWriteInt32(data, mode)) {
            HILOG_ERROR(LOG_APP, "write data failed");
            return -1;
        }
        ret = serv->dispatcher->Dispatch(&serv->object, RGB_LED_WRITE, data, NULL);
    }

    HdfSbufRecycle(data);
    HdfIoServiceRecycle(serv);
    HILOG_INFO(LOG_APP, "[%s] main exit.", LOG_TAG);

    return ret;
}

四、运行程序

系统启动后，命令行运行命令：

rgb_led

五、运行结果

运行结果：

# rgb_led
auto test RGB LED

# rgb_led 1
RGB mode[--R][0x1]
# rgb_led 2
RGB mode[-G-][0x2]
# rgb_led 3
RGB mode[-GR][0x3]
# rgb_led 4
RGB mode[B--][0x4]
# rgb_led 5
RGB mode[B-R][0x5]
# rgb_led 6
RGB mode[BG-][0x6]
# rgb_led 7
RGB mode[BGR][0x7]