OpenHarmony GPIO应用开发-LED

学习于：
https://docs.openharmony.cn/pages/v5.0/zh-cn/device-dev/driver/driver-platform-gpio-develop.md
https://docs.openharmony.cn/pages/v5.0/zh-cn/device-dev/driver/driver-platform-gpio-des.md
通过OpenHarmony官方文档指导可获知：芯片厂商应当按照系统的平台驱动接口实现GPIO控制器驱动后，设备开发人员就可以按照系统GPIO的HDI接口使用GPIO，具体接口函数有：

其中函数参数gpioName指定IO口名，gpio指定IO口的ID，参数具体值由芯片厂商在.hcs配置文件中描述，如海思Hi3516中GPIO控制器驱动的描述：

Hi3516 GPIO控制器驱动自定义属性的描述：

其中属性groupNum指定Hi3516共有12组IO口，bitNum指定每组有8个IO口，由0 ~ 95数值分别表示96个IO，如GPIO2_3，则由数值19表示(2*8 + 3 = 19)。
属性gpioCustomName指定IO口的名称，依此名称可通过函数GpioGetByName获取IO口对应的ID。

接下来通过应用GPIO实现LED驱动：
开发板LED原理图


通过原理图可发现有: GPIO2_3 GPIO3_4 GPIO5_1控制LED的工作。

简单的LED驱动
在上篇简单的HDF驱动驱动源码基础上加入控制一个LED的代码，具体drivers/hdf_core/adapter/khdf/liteos/platform/src/myTestDriver.c驱动源码内容如下：

#include <hdf_device_desc.h>
#include <hdf_log.h>
#include <hdf_base.h>
#include <gpio_if.h>  // GPIO驱动调用接口

static int idGpio = 0;

static int32_t myDispatch(
    struct HdfDeviceIoClient *client, int id, struct HdfSBuf *data, struct HdfSBuf *reply)
{
    HDF_LOGD("### in %s : %d\n", __func__, id);
    GpioWrite(idGpio, id%2); //配置GPIO输出高低电平
    return HDF_SUCCESS;
}

int32_t myBind(struct HdfDeviceObject *obj)
{
    static struct IDeviceIoService testService = {
        .Dispatch = myDispatch,
    };
    obj->service = &testService;
    HDF_LOGD("#### in %s\n", __func__);

    idGpio = GpioGetByName("GPIO2_3"); //获取GPIO的ID
    GpioSetDir(idGpio, GPIO_DIR_OUT); //配置GPIO作输出用途

    return HDF_SUCCESS;
}
int32_t myInit(struct HdfDeviceObject *obj)
{
    HDF_LOGD("#### in %s\n", __func__);
    return HDF_SUCCESS;
}
void myRelease(struct HdfDeviceObject *obj)
{
    HDF_LOGD("#### in %s\n", __func__);
}

struct HdfDriverEntry myTestEntry = {
    .Bind = myBind,
    .Init = myInit,
    .Release = myRelease,
    .moduleName = "myTestDriver",
    .moduleVersion = 1
};
HDF_INIT(myTestEntry);

沿用上篇里的应用程序，当应用程序执行起来后，开发板的LED会在GPIO输出高电平时亮，低电平时熄。

硬件资源分离与可重用的LED驱动
按照OpenHarmony文档指导，硬件相关的资源应当在.hcs配置文件中描述。这里三个LED分别作为一个设备进行描述 ：

然后在vendor/hisilicon/hispark_taurus/hdf_config/目录下创建myLight文件夹，并在文件夹里创建myLight.hcs配置文件，描述设备自定义的属性：

每个节点通过match_attr与设备节点的deviceMatchAttr进行匹配，相同值表示此节点资源由对应的设备使用。 gpioName自定义属性向LED驱动提供LED设备的控制IO。
然后修改vendor/hisilicon/hispark_taurus/hdf_config/hdf.hcs配置文件，增加myLight.hcs文件的使用：

驱动源文件myTestDriver.c代码修改为：

#include <hdf_device_desc.h>
#include <hdf_log.h>
#include <hdf_base.h>
#include <gpio_if.h>
#include <device_resource_if.h>
#include <osal_mem.h>

struct myLightService {
    struct IDeviceIoService service;
    int idGpio;
    const char *gpioName;
};

static int32_t myDispatch(
    struct HdfDeviceIoClient *client, int id, struct HdfSBuf *data, struct HdfSBuf *reply)
{
    struct HdfDeviceObject *obj = client->device;
    struct myLightService *srv = (struct myLightService *)(obj->service);

    HDF_LOGD("### in %s, %s  %d\n", __func__,  srv->gpioName, id);
    GpioWrite(srv->idGpio, !!id);
    return HDF_SUCCESS;
}

int32_t myBind(struct HdfDeviceObject *obj)
{

    struct myLightService *srv = NULL;

    struct DeviceResourceIface *dr = DeviceResourceGetIfaceInstance(HDF_CONFIG_SOURCE);

    srv = OsalMemCalloc(sizeof(struct myLightService));
    dr->GetString(obj->property, "gpioName", &srv->gpioName, NULL);
    srv->service.Dispatch = myDispatch;
    srv->idGpio = GpioGetByName(srv->gpioName);

    GpioSetDir(srv->idGpio, GPIO_DIR_OUT);

    obj->service = &srv->service;

    return HDF_SUCCESS;
}
int32_t myInit(struct HdfDeviceObject *obj)
{
    return HDF_SUCCESS;
}
void myRelease(struct HdfDeviceObject *obj)
{
    struct myLightService *srv = (struct myLightService *)(obj->service);
    OsalMemFree(srv);
}

struct HdfDriverEntry myTestEntry = {
    .Bind = myBind,
    .Init = myInit,
    .Release = myRelease,
    .moduleName = "myTestDriver",
    .moduleVersion = 1
};
HDF_INIT(myTestEntry);

在applications/sample/camera/myhello/mytest.c代码修改为：

#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"

int main(int argc, char *argv[])
{
    if (3 != argc)
    {
        printf("usage: %s  serviceName  num \n", argv[0]);
        return 1;
    }

    struct HdfIoService *srv = HdfIoServiceBind(argv[1]);
    if (srv == NULL) {
        printf("fail to get service\n");
        return 1;
    }

    int ret = srv->dispatcher->Dispatch(&srv->object, atoi(argv[2]), NULL, NULL);
    printf("test end\n");

    HdfIoServiceRecycle(srv);
    return 0;
}

同目录下的BUILD.gn内容如下：

hdf_framework_path = "../../../../../framework"

executable("mytest") {
  sources = [ "mytest.c" ]

  include_dirs = [
    "$hdf_framework_path/ability/sbuf/include",
    "$hdf_framework_path/core/shared/include",
    "$hdf_framework_path/core/host/include",
    "$hdf_framework_path/core/master/include",
    "$hdf_framework_path/include/core",
    "$hdf_framework_path/include/utils",
    "$hdf_framework_path/utils/include",
    "$hdf_framework_path/include/osal",
    "//third_party/bounds_checking_function/include",
    "//base/hiviewdfx/hilog_lite/interfaces/native/innerkits",
  ]

  deps = [
    "//drivers/hdf_core/adapter/uhdf/manager:hdf_core",
    "//drivers/hdf_core/adapter/uhdf/posix:hdf_posix_osal",
    "//base/hiviewdfx/hilog_lite/frameworks/featured:hilog_shared",
  ]

  public_deps = [ "//third_party/bounds_checking_function:libsec_shared" ]
  defines = [ "__USER__" ]
}

然后修改applications/sample/camera/bundle.json文件增加内容：

完成后编译系统，并重新烧录OHOS_Image.bin与rootfs_vfat.img

应用程序执行时通过指定不同的服务名与电平值控制LED，如：

  ./bin/mytest  myTestService0   1      
  ./bin/mytest  myTestService1   1