Button to go to the top of the RecyclerView screen

I want to have a button so that the user, if he has done Scroll, can press and return to the beginning of the screen, that is, to the first item.

Problems:

XML:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/swipeRefreshLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".activity.HomeActivity">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <!-- Este es -->
        <ImageView
            android:id="@+id/arrowUpImageView"
            style="@style/AppTheme.FilterIcon"
            android:layout_above="@id/addFab"
            android:layout_alignParentRight="true"
            android:clickable="true"
            android:layout_margin="@dimen/fab_margin"
            app:srcCompat="@drawable/ic_arrow_up_grey_24dp" />

        <android.support.design.widget.FloatingActionButton
            android:id="@+id/addFab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_alignParentRight="true"
            android:layout_margin="@dimen/fab_margin"
            android:clickable="true"
            app:backgroundTint="@color/progressBarColor"
            app:srcCompat="@drawable/ic_add_white_24dp" />

        <android.support.v7.widget.RecyclerView
            android:id="@+id/postsRecyclerView"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scrollbars="vertical" />

    </RelativeLayout>

</android.support.v4.widget.SwipeRefreshLayout>

Code:

public class HomeActivity extends AppCompatActivity
        implements ViewStub.OnClickListener {


    private ImageView mArrowUpImageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home);

        mArrowUpImageView = findViewById(R.id.arrowUpImageView);
        mArrowUpImageView.setOnClickListener(this);

        // ScrollListener
        mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {

            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);

                int visibility = mLinearLayoutManager.findFirstCompletelyVisibleItemPosition();
                if (visibility != 0) {
                    mArrowUpImageView.setVisibility(View.VISIBLE);
                } else {
                    mArrowUpImageView.setVisibility(View.INVISIBLE);
                }
            }
        });

    }

    @Override
    public void onClick(View v) {
        if (v == mArrowUpImageView) {
            // No funciona
            mLinearLayoutManager.scrollToPositionWithOffset(0,0);
        } 
    }
}

The idea is that when the user has done Scroll down a little, by clicking on the button he can return to the beginning of the screen quickly. The button should appear above FloatingActionButton .

Any ideas?