OpenHarmony驱动服务管理开发

驱动服务管理的开发包括驱动服务的编写、绑定、获取或者订阅，详细步骤如下。

驱动服务编写

// 驱动服务结构的定义
struct ISampleDriverService {
    struct IDeviceIoService ioService;       // 服务结构的首个成员必须是IDeviceIoService类型的成员。
    int32_t (*ServiceA)(void);               // 驱动的第一个服务接口。
    int32_t (*ServiceB)(uint32_t inputCode); // 驱动的第二个服务接口，有多个可以依次往下累加。
};
// 驱动服务接口的实现
int32_t SampleDriverServiceA(void)
{
    // 驱动开发者实现业务逻辑
    return HDF_SUCCESS;
}

int32_t SampleDriverServiceB(uint32_t inputCode)
{
    // 驱动开发者实现业务逻辑
    return HDF_SUCCESS;
}

驱动服务绑定

开发者实现HdfDriverEntry中的Bind指针函数，如下的SampleDriverBind，把驱动服务绑定到HDF框架中。

int32_t SampleDriverBind(struct HdfDeviceObject *deviceObject)
{
    // deviceObject为HDF框架给每一个驱动创建的设备对象，用来保存设备相关的私有数据和服务接口。
    if (deviceObject == NULL) {
        HDF_LOGE("Sample device object is null!");
        return HDF_FAILURE;
    }
    static struct ISampleDriverService sampleDriverA = {
        .ServiceA = SampleDriverServiceA,
        .ServiceB = SampleDriverServiceB,
    };
    deviceObject->service = &sampleDriverA.ioService;
    return HDF_SUCCESS;
}

驱动服务获取

应用程序开发者获取驱动服务有两种方式：通过HDF接口直接获取和通过HDF提供的订阅机制获取。

通过HDF接口直接获取

当驱动服务获取者明确驱动已经加载完成时，获取该驱动的服务可以通过HDF框架提供的能力接口直接获取，如下所示：

const struct ISampleDriverService *sampleService =
        (const struct ISampleDriverService *)DevSvcManagerClntGetService("sample_driver");
if (sampleService == NULL) {
    return HDF_FAILURE;
}
sampleService->ServiceA();
sampleService->ServiceB(5);

通过HDF提供的订阅机制获取

当内核态驱动服务获取者对驱动（同一个host）加载的时机不感知时，可以通过HDF框架提供的订阅机制来订阅该驱动服务。当该驱动加载完成时，HDF框架会将被订阅的驱动服务发布给订阅者（驱动服务获取者），实现方式如下所示：

// 订阅回调函数的编写，当被订阅的驱动加载完成后，HDF框架会将被订阅驱动的服务发布给订阅者，通过这个回调函数给订阅者使用。
// object为订阅者的私有数据，service为被订阅的服务对象。
int32_t TestDriverSubCallBack(struct HdfDeviceObject *deviceObject, const struct HdfObject *service)
{
    const struct ISampleDriverService *sampleService =
        (const struct ISampleDriverService *)service;
    if (sampleService == NULL) {
        return HDF_FAILURE;
    }
    sampleService->ServiceA();
    sampleService->ServiceB(5);
}
// 订阅过程的实现
int32_t TestDriverInit(struct HdfDeviceObject *deviceObject)
{
    if (deviceObject == NULL) {
        HDF_LOGE("Test driver init failed, deviceObject is null!");
        return HDF_FAILURE;
    }
    struct SubscriberCallback callBack;
    callBack.deviceObject = deviceObject;
    callBack.OnServiceConnected = TestDriverSubCallBack;
    int32_t ret = HdfDeviceSubscribeService(deviceObject, "sample_driver", callBack);
    if (ret != HDF_SUCCESS) {
        HDF_LOGE("Test driver subscribe sample driver failed!");
    }
    return ret;
}

HDF开发实例

下面基于HDF框架，提供一个完整的样例，包含配置文件的添加，驱动代码的实现以及用户态程序和驱动交互的流程。

添加配置

在HDF框架的配置文件（例如vendor/hisilicon/xxx/hdf_config/device_info）中添加该驱动的配置信息，如下所示：

root {
    device_info {
        match_attr = "hdf_manager";
        template host {
            hostName = "";
            priority = 100;
            template device {
                template deviceNode {
                    policy = 0;
                    priority = 100;
                    preload = 0;
                    permission = 0664;
                    moduleName = "";
                    serviceName = "";
                    deviceMatchAttr = "";
                }
            }
        }
        sample_host :: host {
            hostName = "sample_host";
            sample_device :: device {
                device0 :: deviceNode {
                    policy = 2;
                    priority = 100;
                    preload = 1;
                    permission = 0664;
                    moduleName = "sample_driver";
                    serviceName = "sample_service";
                }
            }
        }
    }
}

编写驱动代码

基于HDF框架编写的sample驱动代码如下：

#include <fcntl.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include "hdf_log.h"
#include "hdf_base.h"
#include "hdf_device_desc.h"

#define HDF_LOG_TAG sample_driver

#define SAMPLE_WRITE_READ 123

static int32_t HdfSampleDriverDispatch(
    struct HdfDeviceIoClient *client, int id, struct HdfSBuf *data, struct HdfSBuf *reply)
{
    HDF_LOGI("%{public}s: received cmd %{public}d", __func__, id);
    if (id == SAMPLE_WRITE_READ) {
        const char *readData = HdfSbufReadString(data);
        if (readData != NULL) {
            HDF_LOGE("%{public}s: read data is: %{public}s", __func__, readData);
        }
        if (!HdfSbufWriteInt32(reply, INT32_MAX)) {
            HDF_LOGE("%{public}s: reply int32 fail", __func__);
        }
        return HdfDeviceSendEvent(client->device, id, data);
    }
    return HDF_FAILURE;
}

static void HdfSampleDriverRelease(struct HdfDeviceObject *deviceObject)
{
    // release resources here
    return;
}

static int HdfSampleDriverBind(struct HdfDeviceObject *deviceObject)
{
    if (deviceObject == NULL) {
        return HDF_FAILURE;
    }
    static struct IDeviceIoService testService = {
        .Dispatch = HdfSampleDriverDispatch,
    };
    deviceObject->service = &testService;
    return HDF_SUCCESS;
}

static int HdfSampleDriverInit(struct HdfDeviceObject *deviceObject)
{
    if (deviceObject == NULL) {
        HDF_LOGE("%{public}s::ptr is null!", __func__);
        return HDF_FAILURE;
    }
    HDF_LOGI("Sample driver Init success");
    return HDF_SUCCESS;
}

static struct HdfDriverEntry g_sampleDriverEntry = {
    .moduleVersion = 1,
    .moduleName = "sample_driver",
    .Bind = HdfSampleDriverBind,
    .Init = HdfSampleDriverInit,
    .Release = HdfSampleDriverRelease,
};

HDF_INIT(g_sampleDriverEntry);

编写用户程序和驱动交互代码

基于HDF框架编写的用户态程序和驱动交互的代码如下（代码可以放在目录drivers/hdf_core/adapter/uhdf下面编译，BUILD.gn可以参考drivers/hdf_core/framework/sample/platform/uart/dev/BUILD.gn）：

#include <fcntl.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include "hdf_log.h"
#include "hdf_sbuf.h"
#include "hdf_io_service_if.h"

#define HDF_LOG_TAG sample_test
#define SAMPLE_SERVICE_NAME "sample_service"

#define SAMPLE_WRITE_READ 123

int g_replyFlag = 0;

static int OnDevEventReceived(void *priv,  uint32_t id, struct HdfSBuf *data)
{
    const char *string = HdfSbufReadString(data);
    if (string == NULL) {
        HDF_LOGE("fail to read string in event data");
        g_replyFlag = 1;
        return HDF_FAILURE;
    }
    HDF_LOGI("%{public}s: dev event received: %{public}u %{public}s",  (char *)priv, id, string);
    g_replyFlag = 1;
    return HDF_SUCCESS;
}

static int SendEvent(struct HdfIoService *serv, char *eventData)
{
    int ret = 0;
    struct HdfSBuf *data = HdfSbufObtainDefaultSize();
    if (data == NULL) {
        HDF_LOGE("fail to obtain sbuf data");
        return 1;
    }

    struct HdfSBuf *reply = HdfSbufObtainDefaultSize();
    if (reply == NULL) {
        HDF_LOGE("fail to obtain sbuf reply");
        ret = HDF_DEV_ERR_NO_MEMORY;
        goto out;
    }

    if (!HdfSbufWriteString(data, eventData)) {
        HDF_LOGE("fail to write sbuf");
        ret = HDF_FAILURE;
        goto out;
    }

    ret = serv->dispatcher->Dispatch(&serv->object, SAMPLE_WRITE_READ, data, reply);
    if (ret != HDF_SUCCESS) {
        HDF_LOGE("fail to send service call");
        goto out;
    }

    int replyData = 0;
    if (!HdfSbufReadInt32(reply, &replyData)) {
        HDF_LOGE("fail to get service call reply");
        ret = HDF_ERR_INVALID_OBJECT;
        goto out;
    }
    HDF_LOGI("Get reply is: %{public}d", replyData);
out:
    HdfSbufRecycle(data);
    HdfSbufRecycle(reply);
    return ret;
}

int main()
{
    char *sendData = "default event info";
    struct HdfIoService *serv = HdfIoServiceBind(SAMPLE_SERVICE_NAME);
    if (serv == NULL) {
        HDF_LOGE("fail to get service %s", SAMPLE_SERVICE_NAME);
        return HDF_FAILURE;
    }

    static struct HdfDevEventlistener listener = {
        .callBack = OnDevEventReceived,
        .priv ="Service0"
    };

    if (HdfDeviceRegisterEventListener(serv, &listener) != HDF_SUCCESS) {
        HDF_LOGE("fail to register event listener");
        return HDF_FAILURE;
    }
    if (SendEvent(serv, sendData)) {
        HDF_LOGE("fail to send event");
        return HDF_FAILURE;
    }

    while (g_replyFlag == 0) {
        sleep(1);
    }

    if (HdfDeviceUnregisterEventListener(serv, &listener)) {
        HDF_LOGE("fail to  unregister listener");
        return HDF_FAILURE;
    }

    HdfIoServiceRecycle(serv);
    return HDF_SUCCESS;
}

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