net: phylink: add helper function to decode USXGMII word

With the new addition of the USXGMII link partner ability constants we
can now introduce a phylink helper that decodes the USXGMII word and
populates the appropriate fields in the phylink_link_state structure
based on them.
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phylink.c

@@ -2320,6 +2320,49 @@ static void phylink_decode_sgmii_word(struct phylink_link_state *state,
 		state->duplex = DUPLEX_HALF;
 }
 
+/**
+ * phylink_decode_usxgmii_word() - decode the USXGMII word from a MAC PCS
+ * @state: a pointer to a struct phylink_link_state.
+ * @lpa: a 16 bit value which stores the USXGMII auto-negotiation word
+ *
+ * Helper for MAC PCS supporting the USXGMII protocol and the auto-negotiation
+ * code word.  Decode the USXGMII code word and populate the corresponding fields
+ * (speed, duplex) into the phylink_link_state structure.
+ */
+void phylink_decode_usxgmii_word(struct phylink_link_state *state,
+				 uint16_t lpa)
+{
+	switch (lpa & MDIO_USXGMII_SPD_MASK) {
+	case MDIO_USXGMII_10:
+		state->speed = SPEED_10;
+		break;
+	case MDIO_USXGMII_100:
+		state->speed = SPEED_100;
+		break;
+	case MDIO_USXGMII_1000:
+		state->speed = SPEED_1000;
+		break;
+	case MDIO_USXGMII_2500:
+		state->speed = SPEED_2500;
+		break;
+	case MDIO_USXGMII_5000:
+		state->speed = SPEED_5000;
+		break;
+	case MDIO_USXGMII_10G:
+		state->speed = SPEED_10000;
+		break;
+	default:
+		state->link = false;
+		return;
+	}
+
+	if (lpa & MDIO_USXGMII_FULL_DUPLEX)
+		state->duplex = DUPLEX_FULL;
+	else
+		state->duplex = DUPLEX_HALF;
+}
+EXPORT_SYMBOL_GPL(phylink_decode_usxgmii_word);
+
 /**
  * phylink_mii_c22_pcs_get_state() - read the MAC PCS state
  * @pcs: a pointer to a &struct mdio_device.

include/linux/phylink.h

@@ -490,4 +490,7 @@ 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);
+
+void phylink_decode_usxgmii_word(struct phylink_link_state *state,
+				 uint16_t lpa);
 #endif