Как использовать promise для данного кода?

readXmlFIle()
    .then(function(){
        var eshop_jp = JSON.parse(fs.readFileSync('json/jp/eshop_jp.json', 'utf8'));
        return eshop_jp;
    })
.then(function(eshop_jp){..})

readXmlFIle()
    .then(parseJSONfile())
.then(function(eshop_jp){..})

function parseJSONfile(){
        var eshop_jp = JSON.parse(fs.readFileSync('json/jp/eshop_jp.json', 'utf8'));
        return eshop_jp;
}

function readXmlFIle(file, jsonfile) {
	return new Promise(function(resolve, reject){
		var xml_file = fs.readFileSync(file, 'utf8');
		xml2js(xml_file, function (err, result) {
			if(err){
				reject(err);
				return;
			}
			fs.writeFile(jsonfile, JSON.stringify(result,"",2), function(error){
				if (error) {
					reject(error);
					return;
				};
				resolve(result);
			});   
		});
	});
}

readXmlFIle('xml/jp/eshop_jp.xml', 'json/jp/eshop_jp.json').then(function(data){
	// Получили результат
	console.log(data);
}).catch(function(err){
	console.log(err)
});