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编写一个点亮LED灯程序.md 21.91 KB
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Laowang-BearPi authored 2021-12-23 22:56 . 修改点亮LED教程

编写点亮LED灯程序

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。

注: 在学习本教程之前,请确保已经熟练掌握如何编写一个hello_world应用,以下教程篇幅较长,请耐心仔细阅读。

任务介绍

点亮LED主要包含以下任务:

  1. LED驱动代码开发

    驱动开发主要包含以下工作

    • 编写驱动代码
    • 编写驱动编译文件
    • 编写驱动配置文件
  2. 点亮LED业务代码开发

    业务代码开发主要包含以下工作

    • 编写业务代码
    • 编写业务代码编译文件

一、LED灯驱动开发

  1. HDF驱动简介

    HDF框架以组件化的驱动模型作为核心设计思路,为开发者提供更精细化的驱动管理,让驱动开发和部署更加规范。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驱动模型如下图所示:

  2. 确定目录结构。

    在device\st\drivers路径下新建led文件,并创建驱动文件led.c和编译构建文件BUILD.gn 。

    .
    └── device        
        └── st
            └── drivers
                └── led
                    │── led.c
                    └── BUILD.gn
    

    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。

    .
    └── device        
        └── st
            └── bearpi_hm_micro
                └── liteos_a
                    └── hdf_config
                        └── led
                            │── led_config.hcs
  3. LED驱动实现

    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1
    
    enum 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);
    
    
  4. 驱动编译

    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。"##start##"和"##end##"之间为新增配置("##start##"和"##end##"仅用来标识位置,添加完配置后删除这两行)

    import("//drivers/adapter/khdf/liteos/hdf.gni")
    
    group("drivers") {
    deps = [
        "uart",
        "iwdg",
        "i2c",
        "gpio",
        ##start##
        "led",
        ##end##
        "stm32mp1xx_hal",
        "wifi/driver/hi3881",
        "wifi/driver:hdf_vendor_wifi",
    ]
    }
    
  5. 驱动配置

    HDF使用HCS作为配置描述源码,HCS详细介绍参考配置管理介绍。

    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,具体写法如下:

    • 驱动设备描述

      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。 "##start##"和"##end##"之间为新增配置("##start##"和"##end##"仅用来标识位置,添加完配置后删除这两行)

      platform :: host {
      hostName = "platform_host";
      priority = 50;
      ##start##
      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
          }
      }  
      ##end##
      device_gpio :: device {
          device0 :: deviceNode {
              policy = 0;
              priority = 10;
              permission = 0644;
              moduleName = "HDF_PLATFORM_GPIO";
              serviceName = "HDF_PLATFORM_GPIO";
              deviceMatchAttr = "st_stm32mp157_gpio";
          }
      }
    • 驱动私有配置信息

      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
          }
      }

      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,示例如下:

      #include "device_info/device_info.hcs"
      #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

二、点亮LED灯业务代码

  1. 确定目录结构。

    开发者编写业务时,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。

    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        
        └── BearPi
            └── BearPi-HM_Micro
                └── samples
                    │── my_led_app
                       │── my_led_app.c
                       └── BUILD.gn
    
  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;
    }
  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。
  4. 添加新组件

    修改文件build/lite/components/applications.json,添加组件my_sample的配置,如下所示为applications.json文件片段,"##start##"和"##end##"之间为新增配置("##start##"和"##end##"仅用来标识位置,添加完配置后删除这两行),可基于在hello_world基础上在dirs里添加my_led_app路径。在targets里面添加my_led_app目标项。

    {
    "components": [
        ##start##
        {
            "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": [ ]
            }
        },
        ##end##
        {
        "component": "bearpi_sample_app",
        "description": "bearpi_hm_micro samples.",
        "optional": "true",
        "dirs": [
            "applications/BearPi/BearPi-HM_Micro/samples/launcher",
            "applications/BearPi/BearPi-HM_Micro/samples/setting"
        ],
        "targets": [
            "//applications/BearPi/BearPi-HM_Micro/samples/launcher:launcher_hap",
            "//applications/BearPi/BearPi-HM_Micro/samples/setting:setting_hap"
        ],
        "rom": "",
        "ram": "",
        "output": [
            "launcher.so",
            "setting.so"
        ],
        "adapted_kernel": [ "liteos_a","linux" ],
        "features": [],
        "deps": {
            "third_party": [
            "bounds_checking_function",
            "wpa_supplicant"
            ],
            "kernel_special": {},
            "board_special": {},
            "components": [
            "aafwk_lite",
            "appexecfwk_lite",
            "surface",
            "ui",
            "graphic_utils",
            "kv_store",
            "syspara_lite",
            "permission",
            "ipc_lite",
            "samgr_lite",
            "utils_base"
            ]
        }
        },
  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,如下所示代码片段为applications子系统配置,"##start##"和"##end##"之间为新增条目("##start##"和"##end##"仅用来标识位置,添加完配置后删除这两行):

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

三、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 0
OHOS #
Argument 0 is bin/my_led.

Argument 1 is 0.

Get reply is: 0
exit01-01 00:01:06.784 19 43 E 02500/led_driver: Led driver dispatch

OHOS #
OHOS # ./bin/my_led 1
OHOS #
Argument 0 is bin/my_led.

Argument 1 is 1.

Get reply is: 1
exit01-01 00:01:08.833 20 43 E 02500/led_driver: Led driver dispatch

OHOS #
OHOS # ./bin/my_led 2
OHOS #
Argument 0 is bin/my_led.

Argument 1 is 2.

Get reply is: 0
exit01-01 00:01:11.391 21 43 E 02500/led_driver: Led driver dispatch

总结

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,并可以将用户态的数据携带到驱动程序,也可以从驱动程序读出数据,如下图所示为用户态程序与驱动自己数据交互的过程。

  1. 发送LED_WRITE_READ命令到驱动,此处开发者可以自定义创建更多的命令。
  2. 携带数据到驱动,解析出开关灯的动作。
  3. 读取IO口电平状态并通过reply携带到用户程序。

在此希望开发者能仔细琢磨并掌握整个流程,掌握用户态应用程序与内核态驱动程序之间的数据交互流程,以及驱动的编写方式。

C
1
https://gitee.com/bearpi/bearpi-hm_micro_small.git
git@gitee.com:bearpi/bearpi-hm_micro_small.git
bearpi
bearpi-hm_micro_small
BearPi-HM_Micro_small
master

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