net: phylink: support Clause 45 PHYs on SFP+ modules

Some SFP+ modules have Clause 45 PHYs embedded on them, which need a
little more handling in order to ensure that they are correctly setup,
as they switch the PHY link mode according to the negotiated speed.

With Clause 22 PHYs, we assumed that they would operate in SGMII mode,
but this assumption is now false.  Adapt phylink to support Clause 45
PHYs on SFP+ modules.
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phylink.c

@@ -711,7 +711,8 @@ static void phylink_phy_change(struct phy_device *phydev, bool up,
 		    phy_duplex_to_str(phydev->duplex));
 }
 
-static int phylink_bringup_phy(struct phylink *pl, struct phy_device *phy)
+static int phylink_bringup_phy(struct phylink *pl, struct phy_device *phy,
+			       phy_interface_t interface)
 {
 	struct phylink_link_state config;
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(supported);
@@ -729,7 +730,7 @@ static int phylink_bringup_phy(struct phylink *pl, struct phy_device *phy)
 	memset(&config, 0, sizeof(config));
 	linkmode_copy(supported, phy->supported);
 	linkmode_copy(config.advertising, phy->advertising);
-	config.interface = pl->link_config.interface;
+	config.interface = interface;
 
 	ret = phylink_validate(pl, supported, &config);
 	if (ret)
@@ -745,6 +746,7 @@ static int phylink_bringup_phy(struct phylink *pl, struct phy_device *phy)
 	mutex_lock(&phy->lock);
 	mutex_lock(&pl->state_mutex);
 	pl->phydev = phy;
+	pl->phy_state.interface = interface;
 	linkmode_copy(pl->supported, supported);
 	linkmode_copy(pl->link_config.advertising, config.advertising);
 
@@ -807,7 +809,7 @@ int phylink_connect_phy(struct phylink *pl, struct phy_device *phy)
 	if (ret < 0)
 		return ret;
 
-	ret = phylink_bringup_phy(pl, phy);
+	ret = phylink_bringup_phy(pl, phy, pl->link_config.interface);
 	if (ret)
 		phy_detach(phy);
 
@@ -860,7 +862,7 @@ int phylink_of_phy_connect(struct phylink *pl, struct device_node *dn,
 	if (!phy_dev)
 		return -ENODEV;
 
-	ret = phylink_bringup_phy(pl, phy_dev);
+	ret = phylink_bringup_phy(pl, phy_dev, pl->link_config.interface);
 	if (ret)
 		phy_detach(phy_dev);
 
@@ -1809,13 +1811,22 @@ static void phylink_sfp_link_up(void *upstream)
 static int phylink_sfp_connect_phy(void *upstream, struct phy_device *phy)
 {
 	struct phylink *pl = upstream;
+	phy_interface_t interface = pl->link_config.interface;
 	int ret;
 
 	ret = phylink_attach_phy(pl, phy, pl->link_config.interface);
 	if (ret < 0)
 		return ret;
 
-	ret = phylink_bringup_phy(pl, phy);
+	/* Clause 45 PHYs switch their Serdes lane between several different
+	 * modes, normally 10GBASE-R, SGMII. Some use 2500BASE-X for 2.5G
+	 * speeds.  We really need to know which interface modes the PHY and
+	 * MAC supports to properly work out which linkmodes can be supported.
+	 */
+	if (phy->is_c45)
+		interface = PHY_INTERFACE_MODE_NA;
+
+	ret = phylink_bringup_phy(pl, phy, interface);
 	if (ret)
 		phy_detach(phy);