diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index 42f696f139ecb8befb8c3fa215c4a8c50e4d2856..f0db7788f887b9947e0e1aa78d48a9980e80bddf 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -248,9 +248,12 @@ struct ethtool_tunable {
 	void	*data[0];
 };
 
+#define DOWNSHIFT_DEV_DEFAULT_COUNT	0xff
+#define DOWNSHIFT_DEV_DISABLE		0
+
 enum phy_tunable_id {
 	ETHTOOL_PHY_ID_UNSPEC,
-
+	ETHTOOL_PHY_DOWNSHIFT,
 	/*
 	 * Add your fresh new phy tunable attribute above and remember to update
 	 * phy_tunable_strings[] in net/core/ethtool.c