Wp Subtitle

functions.php

 <?php
 add_action( 'edit_form_after_title', 'cpm_add_subtitle_field');
  function cpm_add_subtitle_field() {
    global $post;
    echo '<input type="hidden" name="wp_noncename" id="wp_noncename" value="' . wp_create_nonce( 'wp-subtitle' ) . '" />';
    echo '<div id="subtitlediv" class="top">';
      echo '<div id="subtitlewrap">';
        echo '<input type="text" id="cpmsubtitle" name="cpm_subtitle" value="' . esc_attr( get_post_meta( $post->ID, 'sub_title_meta', true ) ) . '" autocomplete="off" placeholder="' . esc_attr( __( 'Enter subtitle here' ) ) . '" />';
      echo '</div></div>';
  }