http://blog.csdn.net/lushengchu_luis/article/details/11033095

hw_get_module获取硬件模块

看一下CAMERA_HARDWARE_MODULE_ID

hardware/libhardware/include/hardware/camera_common.h:35:#define CAMERA_HARDWARE_MODULE_ID "camera"

看一下我们打印出来的日志

weiqifa@weiqifa-Inspiron-3847:~/weiqifa/log$ grep -wrn "CameraService::onFirstRef" ./
./mobilelog/APLog_2010_0105_214945/main_log.boot:922:01-05 22:49:08.208839   194   194 D CameraService: CameraService::onFirstRef weiqifa
weiqifa@weiqifa-Inspiron-3847:~/weiqifa/log$

hw_get_module 
然后我们就找到了这个地方 
./mediatek/hardware/mtkcam/module/module.h

static
camera_moduleget_camera_module()
{
    camera_module module = {        common: {             tag:                   HARDWARE_MODULE_TAG, 
             module_api_version:    CAMERA_MODULE_API_VERSION_2_1, 
             hal_api_version:       HARDWARE_HAL_API_VERSION, 
             id:                    CAMERA_HARDWARE_MODULE_ID, 
             name:                  "MediaTek Camera Module", 
             author:                "MediaTek", 
             methods:               get_module_methods(), 
             dso:                   NULL, 
             reserved:              {0}, 
        }, 
        get_number_of_cameras:      get_number_of_cameras, 
        get_camera_info:            get_camera_info, 
        set_callbacks:              set_callbacks, 
    };
    return  module;}

• 
  

里面的methods: get_module_methods（）这个就是我们hardware的open函数

open_device(hw_module_t const* module, const char* name, hw_device_t** device)
{    return  NSCam::getCamDeviceManager()->open(module, name, device);
}statichw_module_methods_t*
get_module_methods()
{    static
    hw_module_methods_t
    _methods =
    {
        open: open_device
    };    return  &_methods;
}

open_device就会找到NScam：：getCamDeviceManager()->open 
NSCam这个是一个命名空间，我看了网上的解释，更像是类引用，后面我再跟进去找到open的地方

./mediatek/hardware/mtkcam/devicemgr/CamDeviceManagerBase.cpp

status_t
CamDeviceManagerBase::
open(
    hw_module_t const* module, 
    char const* name, 
    hw_device_t** device
)
{
    RWLock::AutoWLock _l(mRWLock);    //
    return  openDeviceLocked(module, name, device);
}

这里调用到了openDeviceLocked　我们找到这个地方 
./mediatek/hardware/mtkcam/devicemgr/CamDeviceManagerBase.openDevice.cpp

/******************************************************************************
 *
 ******************************************************************************/status_t
CamDeviceManagerBase::
openDeviceLocked(
    hw_module_t const* module, 
    char const* name, 
    hw_device_t** device
)
{
    status_t status = OK;
    sp pDevice = NULL;
    int32_t const i4OpenId = (name != NULL) ? ::atoi(name) : -1;    //
    String8 const s8ClientAppMode = queryClientAppMode();
    uint32_t const version = determineOpenDeviceVersionLocked(s8ClientAppMode, i4OpenId);    //
    MY_LOGD("+ mOpenMap.size:%d mEnumMap.size:%d", mOpenMap.size(), mEnumMap.size());    //
    //  [1] check to see whether it's ready to open.
    if  ( OK != (status = validateOpenLocked(i4OpenId)) )
    {        return  status;
    }    //
    //  [2] get platform
    IPlatform*const pPlatform = getPlatform();    if  ( ! pPlatform )
    {
        MY_LOGE("No Platform");        return  NAME_NOT_FOUND;
    }    //
    //  [3] create device based on device version.
    if  ( version == CAMERA_DEVICE_API_VERSION_1_0 )
    {
        pDevice = pPlatform->createCam1Device(s8ClientAppMode.string(), i4OpenId);
    }    else
    if  ( version >= CAMERA_DEVICE_API_VERSION_3_0 )
    {
        MY_LOGE("Unsupported version:0x%x >= CAMERA_DEVICE_API_VERSION_3_0", version);        return  UNKNOWN_ERROR;
    }    else
    {
        MY_LOGE("Unsupported version:0x%x", version);        return  UNKNOWN_ERROR;
    }    //
    if  ( pDevice == 0 )
    {
        MY_LOGE("device creation failure");        return  NO_MEMORY;
    }    //
    //  [4] open device successfully.
    {
        *device = const_cast(pDevice->get_hw_device());        //
        pDevice->set_hw_module(module);
        pDevice->set_module_callbacks(mpModuleCallbacks);
        pDevice->setDeviceManager(this);        //
        attachDeviceLocked(pDevice);
    }    //
    return  OK;
}