Hi3516DV300驱动开发——编写LED灯控制程序

前言

概述

前面的文章只是涉及到内核态驱动程序的实现，并未涉及到用户态应用程序，以及用户态应用程序与内核态驱动程序之间的数据交互流程，在本示例将演示如何在开发板上运行一个控制LED灯的程序，达到能关闭灯、开启灯以及翻转灯的状态。希望通过本教程的学习，开发者能掌握如何开发一个设备驱动，以及如何在应用层调用驱动。

开发环境

• 硬件平台：润和AI_Camera_Hi3516DV300开发板
• 源码：OpenHarmony 3.1 release
• 环境：Windows+Ubuntu混合开发环境
• 工具：Deveco Device Tool
• 产品：ipcamera_hispark_taurus LiteOS内核OpenHarmony小型系统

参考文章

以下三篇是一些环境的准备以及流程的解析
【FFH】Hi3516DV300 OpenHarmony3.1环境配置及烧录
【FFH】DevEco Device Tool：HDF框架一键生成！
【FFH】HDF驱动开发流程解析

本次编写点亮LED灯程序参考的是BearPi-HM_Micro开发板的示例进行改写实现的在HI3516DV300上的适配。
编写点亮LED灯程序
也参考了大佬的案例代码，也给了很多启发。
示例程序：led_rgb

任务流程

点亮LED主要包含以下任务：

1. 生成HDF框架
   HDF框架由Deveco Device Tool自动生成，相比传统开发模式，可以省去驱动编译文件实现这一步骤，简化hcs配置文件修改以及驱动代码编写。当然，目前只支持Hi3516DV300开发板，如果不支持的话可以参考官方文档自己手动进行编写，配合参考样例代码食用更佳（参考文章已给出）。

2. LED驱动代码开发

• 编写驱动代码
• 编写驱动配置文件

3. 点亮LED业务代码开发

• 编写业务代码
• 编写业务代码编译文件

一，生成HDF驱动框架

打开Deveco Device Tool插件选择HDF并选择好产品，点击+号添加驱动模块，命名为led。

二，LED驱动代码开发

1. 确定目录结构
   驱动代码位于drivers/framework/model/led/driver目录下,

.
└── drivers        
    └── framework
        └── model
            └─── led
                   └── driver
                          └── led_driver.c

驱动编译文件位于drivers/adapter/khdf/liteos/model/led目录下，

.
└── drivers        
    └── adapter
        └── khdf
            └──liteos
                └──model
                    └──led
                        ├── BUILD.gn
                        ├── Kconfig
                        └── Makefile

板级配置入口文件hdf.hcs位于vendor/hisilicon/hispark_taurus/hdf_config目录下，hcs驱动设备描述位于device_info/device_info.hcs,在hdf_config目录下新建led文件夹，并创建私有驱动配置文件led_config.hcs。

.
└── vendor      
    └── hisilicon
        └── hispark_taurus
            └──hdf_config
                ├── hdf.hcs
                ├── device_info
                │   └── device_info.hcs
                ├── led
                     └── led_config.hcs

2. 编写驱动代码
   点击c/c++即可快速跳转到驱动代码目录文件下。
   

修改驱动代码如下：

#include "hdf_device_desc.h" 
#include "hdf_log.h"         
#include "device_resource_if.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1

//0表示关闭，1表示开启，2表示翻转
enum LedOps {
    LED_OFF,
    LED_ON,  
    LED_TOGGLE,
};

struct Hi3516Led {
    uint32_t gpioNum;
};
static struct Hi3516Led g_Hi3516Led;
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_Hi3516Led.gpioNum, GPIO_VAL_HIGH);
            status = 1;
            break;
        /* 关灯 */
        case LED_OFF:                                           
            GpioWrite(g_Hi3516Led.gpioNum, GPIO_VAL_LOW);
            status = 0;
            break;
        /* 状态翻转 */
        case LED_TOGGLE:
            if(status == 0)
            {
                GpioWrite(g_Hi3516Led.gpioNum, GPIO_VAL_HIGH);
                status = 1;
            }
            else
            {
                GpioWrite(g_Hi3516Led.gpioNum, GPIO_VAL_LOW);
                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 Hi3516LedReadDrs(struct Hi3516Led *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 Hi3516Led *led = &g_Hi3516Led;
    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 = Hi3516LedReadDrs(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 = "led_driver",//必须和device_info.hcs文件定义的modeleNmae一样
    .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);

3. 编写驱动配置文件
   3.1 修改驱动设备描述
   点击hcs即可快速跳转到驱动设备描述文件下
   
   添加驱动私有数据匹配的关键字，用于获取私有配置信息。
   

led :: host{
		    hostName = "led_host";        // Host name. The host node is used to store a certain type of drivers.
		    priority = 100;                         //Host startup priority (0-200). A larger value indicates a lower priority. The default value 100 is recommended. If the priorities are the same, the host loading sequence is random.
		    device_led :: device {        // Device node of sample
		        device0 :: deviceNode {             // DeviceNode of the sample driver
		            policy = 2;                     // Driver service release policy. For details, see section Driver Service Management.
		            priority= 100;                  // Driver startup priority (0-200). A larger value indicates a lower priority. The default value 100 is recommended. If the priorities are the same, the device loading sequence is random.
		            preload = 0;                    // On-demand loading of the driver. For details, see "NOTE" at the end of this section.
		            permission = 0664;              // Permission for the driver to create device nodes.
		            moduleName = "led_driver";       // Driver name. The value of this field must be the same as the value of moduleName in the driver entry structure.
		            serviceName = "led_service";     // Name of the service released by the driver. The name must be unique.
		            deviceMatchAttr = "led_config";         // Keyword matching the private data of the driver. The value must be the same as that of match_attr in the private data configuration table of the driver.

3.2 编写驱动私有配置信息
在vendor/hisilicon/hispark_taurus/hdf_config/led/led_config.hcs中添加LED私有配置描述。Hi3516DV300的绿色LED引脚号为19，设置led_gpio_num = 19，可以修改led_gpio_num的值来改变要操作的gpio，通过私有配置的好处是使驱动能够更好的适配各种设备以及开发板。

root {
    LedDriverConfig {
        led_gpio_num = 19;
        match_attr = "led_config";   //该字段的值必须和device_info.hcs中的deviceMatchAttr值一致
    }
}

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vendor/hisilicon/hispark_taurus/hdf_config/hdf.hcs，示例如下：

#include "led/led_config.hcs"

• 小结

1. device_info.hcs文件中的moduleName必须要和驱动文件中的moduleName字段匹配，这样驱动才会加载起来。
2. device_info.hcs文件中的deviceMatchAttr的字段必须和私有配置文件中led_config.hcs的match_attr的字段匹配，这样私有配置才能生效。
3. device_info.hcs文件中的serviceName的字段需和业务代码获取服务用到的函数的serviceName参数匹配，这样用户态才能成功获取到服务。用户程序是无法直接访问驱动的，当只有驱动程序向用户态暴露server后，用户程序才能通过Dispatch的方式发送指令到驱动程序，这是用户态程序与驱动程序数据交互的关键。

struct HdfIoService *HdfIoServiceBind(const char *serviceName)

三，点亮LED灯业务代码

1. 确定目录结构。
   开发者编写Hi3516DV300业务时，务必先在./applications/sample/camera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。
   例如：在app下新增业务my_led_app，其中my_led_app.c为业务代码，BUILD.gn为编译脚本，具体规划目录结构如下：

.
└── applications        
    └── sample
        └── camera
               │── my_led_app
                   │── my_led_app.c
                   └── BUILD.gn

2. 编写业务代码。(my_led_app.c)

#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 "led_service"//与device_info.hcs文件中的serviceName的字段匹配

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;
}

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。

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。

4. 添加新组件
   在./build/lite/components/applications.json中为application子系统添加组件my_sample,将目标和路径添加到组件配置中。

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

5. 修改单板配置文件
   在vendor/hisilicon/hispark_taurus/config.json文件中为开发板的application子系统添加组件，新增my_sample组件的条目，使样例能编译进开发板工程中。
   

 { "component": "my_sample", "features":[] },

四，运行结果

示例代码编译、烧录后，在命令行输入以下指令可控制开发板的LED灯。

关闭LED:

./bin/my_led 0

开启LED:

./bin/my_led 1

翻转LED:

./bin/my_led 2

从以下日志的Get reply中可以收到驱动上报的当前灯的状态，"0"表示当前灯为关闭状态，"1"表示当前灯为打开状态。

OHOS #
OHOS # ./bin/my_led 1

Argument 0 is bin/my_led.

Argument 1 is 1.

01-01 00:01:07.847 16 48 E 02500/led_driver: Led driver dispatch
Get reply is: 1
exitOHOS #
OHOS # ./bin/my_led 0

Argument 0 is bin/my_led.

Argument 1 is 0.

01-01 00:01:11.878 17 48 E 02500/led_driver: Led driver dispatch
Get reply is: 0
exitOHOS #
OHOS # ./bin/my_led 2

Argument 0 is bin/my_led.

Argument 1 is 2.

Get reply is: 1

演示视频地址：
Hi3516DV300LED灯控制程序演示

<br>
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