net: phylink: pcs: add 802.3 clause 45 helpers

Implement helpers for PCS accessed via the MII bus using 802.3 clause
45 cycles for 10GBASE-R. Only link up/down is supported, 10G full
duplex is assumed.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phylink.c

@@ -2274,4 +2274,34 @@ void phylink_mii_c22_pcs_an_restart(struct mdio_device *pcs)
 }
 EXPORT_SYMBOL_GPL(phylink_mii_c22_pcs_an_restart);
 
+#define C45_ADDR(d,a)	(MII_ADDR_C45 | (d) << 16 | (a))
+void phylink_mii_c45_pcs_get_state(struct mdio_device *pcs,
+				   struct phylink_link_state *state)
+{
+	struct mii_bus *bus = pcs->bus;
+	int addr = pcs->addr;
+	int stat;
+
+	stat = mdiobus_read(bus, addr, C45_ADDR(MDIO_MMD_PCS, MDIO_STAT1));
+	if (stat < 0) {
+		state->link = false;
+		return;
+	}
+
+	state->link = !!(stat & MDIO_STAT1_LSTATUS);
+	if (!state->link)
+		return;
+
+	switch (state->interface) {
+	case PHY_INTERFACE_MODE_10GBASER:
+		state->speed = SPEED_10000;
+		state->duplex = DUPLEX_FULL;
+		break;
+
+	default:
+		break;
+	}
+}
+EXPORT_SYMBOL_GPL(phylink_mii_c45_pcs_get_state);
+
 MODULE_LICENSE("GPL v2");

include/linux/phylink.h

@@ -323,4 +323,6 @@ int phylink_mii_c22_pcs_set_advertisement(struct mdio_device *pcs,
 					const struct phylink_link_state *state);
 void phylink_mii_c22_pcs_an_restart(struct mdio_device *pcs);
 
+void phylink_mii_c45_pcs_get_state(struct mdio_device *pcs,
+				   struct phylink_link_state *state);
 #endif