custom meta box

<?php
add_action('add_meta_boxes', 'lonchera_add_infoproducto');

function lonchera_add_infoproducto()
{
    add_meta_box('lonchera_infoproducto', 'Informaci&oacute;n del producto', 'lonchera_infoproducto', 'post', 'normal', 'default');
}

function lonchera_infoproducto() {
    global $post, $wp_locale;

    wp_nonce_field( plugin_basename(__FILE__), 'lonchera_infoproducto_noncename' );

    $codigo = get_post_meta($post->ID, 'codigo', true);

    $lol = '<label for="marca">C&oacute;digo:</label> <input type="text" name="lonchera_codigo" value="'.$codigo.'" id="lonchera_marca" />';

    echo $lol;
}

function lonchera_save_infoproducto($post_id, $post) {

    if ( !wp_verify_nonce( $_POST['lonchera_infoproducto_noncename'], plugin_basename(__FILE__) )) {
        return $post_id;
    }

    // verify if this is an auto save routine. If it is our form has not been submitted, so we dont want
    // to do anything
    if ( defined('DOING_AUTOSAVE') && DOING_AUTOSAVE ) {
        return $post_id;
    }


    // Check permissions
    if ( 'page' == $_POST['post_type'] ) {
        if ( !current_user_can( 'edit_page', $post_id ) )
        return $post_id;
    } else {
        if ( !current_user_can( 'edit_post', $post_id ) )
        return $post_id;
    }

    // OK, we're authenticated: we need to find and save the data
    // We'll put it into an array to make it easier to loop though.

    $metas['codigo'] = $_POST['lonchera_codigo'];

    foreach ($metas as $key => $value) { // Cycle through the $events_meta array!
        if( $post->post_type == 'revision' ) return; // Don't store custom data twice
        $value = implode(',', (array)$value); // If $value is an array, make it a CSV (unlikely)
        if(get_post_meta($post->ID, $key, FALSE)) { // If the custom field already has a value
            update_post_meta($post->ID, $key, $value);
        } else { // If the custom field doesn't have a value
            add_post_meta($post->ID, $key, $value);
        }
        //if(!$value) delete_post_meta($post->ID, $key); // Delete if blank
    }


}

add_action('save_post', 'lonchera_save_infoproducto', 1, 2);
?>