How can i get discounts info cat product list?

How can i get discounts info cat product list?
I have added this code at category.php:
if (isset($this->request->get['product_id'])) {
$product_id = (int)$this->request->get['product_id'];
} else {
$product_id = 0;
}
$this->load->model('catalog/product');
$discounts = $this->model_catalog_product->getProductDiscounts($this->request->get['product_id']);
$this->data['discounts'] = array();
foreach ($discounts as $discount) {
$this->data['discounts'][] = array(
'quantity' => $discount['quantity'],
'price' => $this->currency->format($this->tax->calculate($discount['price'], $product_info['tax_class_id'], $this->config->get('config_tax')))
);
}

but can not get discouts info at category.tpl.

How should i do if i want get discouts info at category.tpl?

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