Magento 1: Get Configurable Product ids/skus from simple product

magento-1_get_configurable_product_ids_skus_from_simple_product.php

/**
 * Return parent product id(s) array.
 *
 * @param Mage_Catalog_Model_Product $product
 * @return array|bool|null
 */
public function getParentIds(Mage_Catalog_Model_Product $product)
{
    $id = $product->getId();
    $type = $product->getTypeId();

    $parentIds = null;

    if ($type == 'simple') {
        $parentIds = Mage::getResourceSingleton('catalog/product_type_configurable')
            ->getParentIdsByChild($id);
    }

    if (count($parentIds)) {
        return $parentIds;
    } else {
        return false;
    }

}

/**
 * Returns parent skus
 *
 * @param Mage_Catalog_Model_Product $product
 * @param bool $asString if set to 'true', skus as comma separated string.
 */

public function getParentSkus(Mage_Catalog_Model_Product $product, $asString = false){

    $parentIds = $this->getParentIds($product);

    $products = Mage::getModel('catalog/product')->getCollection()
        ->addAttributeToSelect(array('sku'))
        ->addIdFilter($parentIds);

    $parentSkus = null;

    foreach ($products as $product) {
        $parentSkus[]=$product->getSku();
    }

    if($asString){
        return implode('|',$parentSkus);
    }else{
        return $parentSkus;
    }
}