Get phone orientation but fix screen orientation to portrait

Could you satisfy your requirement with the accelerometer? If so, perhaps something like this (untested) fragment would suit your purposes.

SensorManager sensorManager = (SensorManager) this.getSystemService(Context.SENSOR_SERVICE);
        sensorManager.registerListener(new SensorEventListener() {
            int orientation=-1;;

            @Override
            public void onSensorChanged(SensorEvent event) {
                if (event.values[1]<6.5 && event.values[1]>-6.5) {
                    if (orientation!=1) {
                        Log.d("Sensor", "Landscape");
                    }
                    orientation=1;
                } else {
                    if (orientation!=0) {
                        Log.d("Sensor", "Portrait");
                    }
                    orientation=0;
                }
            }

            @Override
            public void onAccuracyChanged(Sensor sensor, int accuracy) {
                // TODO Auto-generated method stub

            }
        }, sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_GAME);

Here is a multi-purpose class for easily managing screen orientation changes:

public class OrientationManager extends OrientationEventListener {

    public enum ScreenOrientation {
        REVERSED_LANDSCAPE, LANDSCAPE, PORTRAIT, REVERSED_PORTRAIT
    }

    public ScreenOrientation screenOrientation; 
    private OrientationListener listener;

    public OrientationManager(Context context, int rate, OrientationListener listener) {
        super(context, rate);
        setListener(listener);
    }

    public OrientationManager(Context context, int rate) {
        super(context, rate);
    }

    public OrientationManager(Context context) {
        super(context);
    }

    @Override
    public void onOrientationChanged(int orientation) {
        if (orientation == -1){
            return;
        }
        ScreenOrientation newOrientation;
        if (orientation >= 60 && orientation <= 140){
            newOrientation = ScreenOrientation.REVERSED_LANDSCAPE;
        } else if (orientation >= 140 && orientation <= 220) {
            newOrientation = ScreenOrientation.REVERSED_PORTRAIT;
        } else if (orientation >= 220 && orientation <= 300) {
            newOrientation = ScreenOrientation.LANDSCAPE;
        } else {
            newOrientation = ScreenOrientation.PORTRAIT;                    
        }
        if(newOrientation != screenOrientation){
            screenOrientation = newOrientation;
            if(listener != null){
                listener.onOrientationChange(screenOrientation);
            }           
        }
    }

    public void setListener(OrientationListener listener){
        this.listener = listener;
    }

    public ScreenOrientation getScreenOrientation(){
        return screenOrientation;
    }

    public interface OrientationListener {

        public void onOrientationChange(ScreenOrientation screenOrientation);
    }
}

This is way more simple, reusable, and you can also get REVERSE_LANDSCAPE and REVERSE_PORTRAIT orientations.

You must implement OrientationListener in order to get notified only when an orientation change occurs.

Don't forget to call orientationManager.enable() to begin orientation tracking, and then calling orientationManager.disable() (this two methods are inherited from OrientationEventListener class)

UPDATE: use case example

MyFragment extends Fragment implements OrientationListener {

    ...

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        orientationManager = new OrientationManager(getActivity(), SensorManager.SENSOR_DELAY_NORMAL, this);
        orientationManager.enable();        
    }

    @Override
    public void onOrientationChange(ScreenOrientation screenOrientation) {
        switch(screenOrientation){
            case PORTRAIT:
            case REVERSED_PORTRAIT:
                MainActivityBase.getInstance().setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
            break;
            case REVERSED_LANDSCAPE:
                MainActivityBase.getInstance().setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE);
            break;
            case LANDSCAPE:
                MainActivityBase.getInstance().setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
            break;
        }
    }
}