当前位置：网站首页>[FFH] little bear driver calling process (take calling LED light driver as an example)

[FFH] little bear driver calling process (take calling LED light driver as an example)

2022-07-02 12:25:00 【Harmonyos technology community】

The Spring Festival keeps changing , This article is being attended 「 Project starlight - Spring festival activities 」

One 、 Process Overview

The process of driving calls is very similar to that of pure code development , This article focuses on the logic that drives the call .

Create directories and corresponding source files –> Write driver calling code –> Write and compile build files BUILD.gn–> Compile, burn and run

Two 、 Source directory structure

stay ./applications/BearPi/BearPi-HM_Micro/samples/ Create under directory

my_led_app Source directory

*my_led_app.c Driver call source code

*BUILD.gn Source compilation script

As shown in the figure

【FFH】 The little bear sect driver calls the process （ By calling LED Take lamp drive as an example ）_OpenHarmony

3、 ... and 、 Write driver calling code

stay my_led_app.c Write the following code in

#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;
    }
    /*  Write data  */
    if (!HdfSbufWriteUint8(data, eventData))
    {
        printf("fail to write sbuf!\r\n");
        ret = HDF_FAILURE;
        goto out;
    }
    /*  adopt Dispatch Send to driver  */
    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;
    /*  Read the reply data of the driver  */
    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;
    
    /*  Access to services  */
    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;
}

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This part is the key part of this article

OpenHarmony The driver call in the device development of is different from the driver development of single chip microcomputer , In the past, the driver call of single chip microcomputer often used the way of library function call , but OpenHarmony The driver call of adopts that the driver exposes a server, Procedure passed Dispatch How to send instructions . It's a bit like ROS Topic publishing and subscription in the message communication mechanism . stay OpenHarmony This part of the program called by the driver in belongs to the user program , It is the content of user mode , The driver is the content of kernel state . So the user program cannot directly access the driver , The above code passes Dispatch Send instructions to the driver to realize LED The light goes on and off .

3.1 Send instructions to the driver

Let's take a look at my_led_app.c in SendEvent function Pass through Dispatch The code sent to the driver

/*  adopt Dispatch Send to driver  */
    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;

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This code implements sending instructions to the driver

The code received by the driver instruction is Last article Medium led.c In the driver code LedDriverDispatch function

// Dispatch It is used to process messages sent from user mode 
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)
    {
    /*  Received from user status LED_WRITE_READ command  */
    case LED_WRITE_READ:
        /*  Read data The data in , Assign a value to contrl */
        HdfSbufReadUint8(data,&contrl);                  
        switch (contrl)
        {
        /*  turn on the light  */
        case LED_ON:                                            
            GpioWrite(g_Stm32Mp1ILed.gpioNum, GPIO_VAL_LOW);
            status = 1;
            break;
        /*  Turn off the lights  */
        case LED_OFF:                                           
            GpioWrite(g_Stm32Mp1ILed.gpioNum, GPIO_VAL_HIGH);
            status = 0;
            break;
        /*  State flip  */
        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;
        }
        /*  hold LED Write the status value of reply,  Can be brought to the user program  */
        if (!HdfSbufWriteInt32(reply, status))                
        {
            HDF_LOGE("replay is fail");
            return HDF_FAILURE;
        }
        break;
    default:
        break;
    }
    return HDF_SUCCESS;
}

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3.2 Receive data from the driver

Just realized sending instructions from user state to inner core state , Empathy , Kernel mode can also send data to user mode .

Let's take a look at the driver code that sends LED Code of status information （ stay led.c in LedDriverDispatch Part of the function ）

/*  hold LED Write the status value of reply,  Can be brought to the user program  */
        if (!HdfSbufWriteInt32(reply, status))                
        {
            HDF_LOGE("replay is fail");
            return HDF_FAILURE;
        }

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The following is the part received by the user program

/*  Read the reply data of the driver  */
    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);

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Four 、 Write and compile build files BUILD.gn

stay BUILD.gn Add the following code in

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",
    ]
}

     
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