net: phylink: add phylink_expects_phy() method

[ Upstream commit 653a180957 ]

Provide phylink_expects_phy() to allow MAC drivers to check if it
is expecting a PHY to attach to. Since fixed-linked setups do not
need to attach to a PHY.

Provides a boolean value as to if the MAC should expect a PHY.
Returns true if a PHY is expected.

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Michael Sit Wei Hong <michael.wei.hong.sit@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: fe2cfbc968 ("net: stmmac: check if MAC needs to attach to a PHY")
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/net/phy/phylink.c

@@ -1552,6 +1552,25 @@ void phylink_destroy(struct phylink *pl)
 }
 EXPORT_SYMBOL_GPL(phylink_destroy);
 
+/**
+ * phylink_expects_phy() - Determine if phylink expects a phy to be attached
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ *
+ * When using fixed-link mode, or in-band mode with 1000base-X or 2500base-X,
+ * no PHY is needed.
+ *
+ * Returns true if phylink will be expecting a PHY.
+ */
+bool phylink_expects_phy(struct phylink *pl)
+{
+	if (pl->cfg_link_an_mode == MLO_AN_FIXED ||
+	    (pl->cfg_link_an_mode == MLO_AN_INBAND &&
+	     phy_interface_mode_is_8023z(pl->link_config.interface)))
+		return false;
+	return true;
+}
+EXPORT_SYMBOL_GPL(phylink_expects_phy);
+
 static void phylink_phy_change(struct phy_device *phydev, bool up)
 {
 	struct phylink *pl = phydev->phylink;

include/linux/phylink.h

@@ -566,6 +566,7 @@ struct phylink *phylink_create(struct phylink_config *, struct fwnode_handle *,
 			       phy_interface_t iface,
 			       const struct phylink_mac_ops *mac_ops);
 void phylink_destroy(struct phylink *);
+bool phylink_expects_phy(struct phylink *pl);
 
 int phylink_connect_phy(struct phylink *, struct phy_device *);
 int phylink_of_phy_connect(struct phylink *, struct device_node *, u32 flags);