How to get parent SKU from associated simple product in Magento 1.9?

Here is my code, but it is only generating the simple product SKU where I want to get it for the configurable product page also. I used it to restrict a block on a simple and configurable product page.

$_cId = 0;

if(Mage::getSingleton('customer/session')->isLoggedIn()) {
    $customerData = Mage::getSingleton('customer/session')->getCustomer();
    $_cId = $customerData->getId();
}

$orderItems = Mage::getResourceModel('sales/order_item_collection')
    ->addFieldToFilter('sku', $this->getProductInfo()->getSku())
    ->toArray(array('order_id'));

$orderIds = array_unique(array_map(
    function($orderItem) {
        return $orderItem('order_id');
    },
    $orderItems('items')));

$orderCollection = Mage::getResourceModel('sales/order_collection')
    ->addFieldToFilter('entity_id',   array('in'  => $orderIds))
    ->addFieldToFilter('customer_id', array('eq' => $_cId));
$orderCollection->getSelect()->group('customer_id');

$customerCollection = Mage::getModel('customer/customer')->getCollection()
    ->addFieldToFilter('entity_id', array('in' => $orderCollection->getColumnValues('customer_id')));

foreach ($customerCollection as $customer) {
    // Code
}