qcom android GPS 启动流程

1 LocationManagerService启动及初始化过程

(1) 在SystemServer.java的startOtherServices中添加LocationManagerService的代码如下：

try {
    location = new LocationManagerService(context);
    ServiceManager.addService(Context.LOCATION_SERVICE, location);
} catch (Throwable e) {
    reportWtf("starting Location Manager", e);
}

(2) 在systemReady中调用systemRunning, 启动LocationManagerService的代码如下：

try {
    if (locationF != null) locationF.systemRunning();
} catch (Throwable e) {
    reportWtf("Notifying Location Service running", e);
}

(3) 准备GnssLocationProvider，LocationManagerService的systemRunning函数中会调用 loadProvidersLocked， 其代码如下：

private void loadProvidersLocked() {    
    // create a passive location provider, which is always enabled
    PassiveProvider passiveProvider = new PassiveProvider(this);
    addProviderLocked(passiveProvider);
    mEnabledProviders.add(passiveProvider.getName());
    mPassiveProvider = passiveProvider;

    if (GnssLocationProvider.isSupported()) {
        // Create a gps location provider
        GnssLocationProvider gnssProvider = new GnssLocationProvider(mContext, this,
                mLocationHandler.getLooper());
        mGnssSystemInfoProvider = gnssProvider.getGnssSystemInfoProvider();
        ......
    }
    ......
}

(4) GnssLocationProvider的class_init_native方法。

该方法是一个静态方法，会在isSupported方法之前被调用。最终会调用到native函数中：android_location_GnssLocationProvider_class_init_native。
在这个函数中实现对gps.default.so的加载。

static void android_location_GnssLocationProvider_class_init_native(JNIEnv* env, jclass clazz) {
    int err;
    hw_module_t* module;
    .......
    err = hw_get_module(GPS_HARDWARE_MODULE_ID, (hw_module_t const**)&module);
    if (err == 0) {
        hw_device_t* device;
        err = module->methods->open(module, GPS_HARDWARE_MODULE_ID, &device);
        if (err == 0) {
            gps_device_t* gps_device = (gps_device_t *)device;
            sGpsInterface = gps_device->get_gps_interface(gps_device);
        }
    }
    if (sGpsInterface) {
        ......
    }
}

(5) sGpsInterface 接口：

static const GpsInterface sLocEngInterface =
{
   sizeof(GpsInterface),
   loc_init,
   loc_start,
   loc_stop,
   loc_cleanup,
   loc_inject_time,
   loc_inject_location,
   loc_delete_aiding_data,
   loc_set_position_mode,
   loc_get_extension
};

(6) Others interface:

具体实现请参考：/LINUX/android/hardware/qcom/gps/loc_api/libloc_api_50001/loc.cpp

if (sGpsInterface) {
    sGpsXtraInterface =
        (const GpsXtraInterface*)sGpsInterface->get_extension(GPS_XTRA_INTERFACE);
    sAGpsInterface =
        (const AGpsInterface*)sGpsInterface->get_extension(AGPS_INTERFACE);
    sGpsNiInterface =
        (const GpsNiInterface*)sGpsInterface->get_extension(GPS_NI_INTERFACE);
    sGpsDebugInterface =
        (const GpsDebugInterface*)sGpsInterface->get_extension(GPS_DEBUG_INTERFACE);
    sAGpsRilInterface =
        (const AGpsRilInterface*)sGpsInterface->get_extension(AGPS_RIL_INTERFACE);
    sGpsGeofencingInterface =
        (const GpsGeofencingInterface*)sGpsInterface->get_extension(GPS_GEOFENCING_INTERFACE);
    sGpsMeasurementInterface =
        (const GpsMeasurementInterface*)sGpsInterface->get_extension(GPS_MEASUREMENT_INTERFACE);
    sGpsNavigationMessageInterface =
        (const GpsNavigationMessageInterface*)sGpsInterface->get_extension(
                GPS_NAVIGATION_MESSAGE_INTERFACE);
    sGnssConfigurationInterface =
        (const GnssConfigurationInterface*)sGpsInterface->get_extension(
                GNSS_CONFIGURATION_INTERFACE);
}

(7) GPS framework 回调函数库：

 GpsCallbacks sGpsCallbacks = {
    sizeof(GpsCallbacks),
    location_callback,
    status_callback,
    sv_status_callback,
    nmea_callback,
    set_capabilities_callback,
    acquire_wakelock_callback,
    release_wakelock_callback,
    create_thread_callback,
    request_utc_time_callback,
    set_system_info_callback,
    gnss_sv_status_callback,
};

GpsXtraCallbacks sGpsXtraCallbacks = {
    xtra_download_request_callback,
    create_thread_callback,
};

AGpsCallbacks sAGpsCallbacks = {
    agps_status_callback,
    create_thread_callback,
};

GpsNiCallbacks sGpsNiCallbacks = {
    gps_ni_notify_callback,
    create_thread_callback,
};

AGpsRilCallbacks sAGpsRilCallbacks = {
    agps_request_set_id,
    agps_request_ref_location,
    create_thread_callback,
};

......

2 GPS启动流程

(1) GnssLocationProvider.java里处理GPS启动，关闭请求

@Override    public void handleMessage(Message msg) {
    int message = msg.what;
    switch (message) {
        case ENABLE:
            if (msg.arg1 == 1) {
                handleEnable();
            } else {
                handleDisable();
            }
            break;
    ......
    }
}

(2) handleEnable里启动native层初始化动作

private void handleEnable() {
    if (DEBUG) Log.d(TAG, "handleEnable");
    synchronized (mLock) {
        if (mEnabled) return;
        mEnabled = true;
    }
    boolean enabled = native_init();
    if (enabled) {
        mSupportsXtra = true;
    } else {
        synchronized (mLock) {
            mEnabled = false;
        }
        Log.w(TAG, "Failed to enable location provider");
    }
}

(3) GPS native初始化，即GnssLocationProvider初始化过程：

static jboolean android_location_GnssLocationProvider_init(JNIEnv* env, jobject obj){
    // this must be set before calling into the HAL library
    if (!mCallbacksObj)
        mCallbacksObj = env->NewGlobalRef(obj);

    // fail if the main interface fails to initialize
    if (!sGpsInterface || sGpsInterface->init(&sGpsCallbacks) != 0)
        return JNI_FALSE;

    // if XTRA initialization fails we will disable it by sGpsXtraInterface to NULL,
    // but continue to allow the rest of the GPS interface to work.
    if (sGpsXtraInterface && sGpsXtraInterface->init(&sGpsXtraCallbacks) != 0)
        sGpsXtraInterface = NULL;
    ......
    return JNI_TRUE;
}

(4) Loc_init, 设置framework层回调函数，初始化loc eng，并通过modem接口上电：

static int loc_init(GpsCallbacks* callbacks){
    int retVal = -1;
    ENTRY_LOG();
    LOC_API_ADAPTER_EVENT_MASK_T event;
    ......
    LocCallbacks clientCallbacks = {local_loc_cb, /* location_cb */
                                    callbacks->status_cb, /* status_cb */
                                    local_sv_cb, /* sv_status_cb */
                                    callbacks->nmea_cb, /* nmea_cb */
                                    callbacks->set_capabilities_cb, /* set_capabilities_cb */
                                    callbacks->acquire_wakelock_cb, /* acquire_wakelock_cb */
                                    callbacks->release_wakelock_cb, /* release_wakelock_cb */
                                    callbacks->create_thread_cb, /* create_thread_cb */
                                    NULL, /* location_ext_parser */
                                    NULL, /* sv_ext_parser */
                                    callbacks->request_utc_time_cb, /* request_utc_time_cb */
                                    callbacks->set_system_info_cb, /* set_system_info_cb */
                                    callbacks->gnss_sv_status_cb, /* gnss_sv_status_cb */
                                    };

    gps_loc_cb = callbacks->location_cb;
    gps_sv_cb = callbacks->sv_status_cb;

    retVal = loc_eng_init(loc_afw_data, &clientCallbacks, event, NULL);
    ......

    if(retVal) {
        LOC_LOGE("loc_eng_init() fail!");
        goto err;
    }

    loc_afw_data.adapter->setPowerVoteRight(loc_get_target() == TARGET_QCA1530);
    loc_afw_data.adapter->setPowerVote(true);

    LOC_LOGD("loc_eng_init() success!");

err:
    EXIT_LOG(%d, retVal);
    return retVal;
}

(5) LocEngInit及msgTask初始化流程：