net: phylink: provide phylink_get_inband_type()

Provide a function to get the type of the inband signalling used for
a PHY interface type. This will be used in the subsequent patch to
address problems with 10G optical modules.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/E1uslws-00000001SP5-1R2R@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Russell King (Oracle)

drivers/net/phy/phylink.c

@@ -1016,6 +1016,42 @@ static void phylink_pcs_an_restart(struct phylink *pl)
 		pl->pcs->ops->pcs_an_restart(pl->pcs);
 }
 
+enum inband_type {
+	INBAND_NONE,
+	INBAND_CISCO_SGMII,
+	INBAND_BASEX,
+};
+
+static enum inband_type phylink_get_inband_type(phy_interface_t interface)
+{
+	switch (interface) {
+	case PHY_INTERFACE_MODE_SGMII:
+	case PHY_INTERFACE_MODE_QSGMII:
+	case PHY_INTERFACE_MODE_QUSGMII:
+	case PHY_INTERFACE_MODE_USXGMII:
+	case PHY_INTERFACE_MODE_10G_QXGMII:
+		/* These protocols are designed for use with a PHY which
+		 * communicates its negotiation result back to the MAC via
+		 * inband communication. Note: there exist PHYs that run
+		 * with SGMII but do not send the inband data.
+		 */
+		return INBAND_CISCO_SGMII;
+
+	case PHY_INTERFACE_MODE_1000BASEX:
+	case PHY_INTERFACE_MODE_2500BASEX:
+		/* 1000base-X is designed for use media-side for Fibre
+		 * connections, and thus the Autoneg bit needs to be
+		 * taken into account. We also do this for 2500base-X
+		 * as well, but drivers may not support this, so may
+		 * need to override this.
+		 */
+		return INBAND_BASEX;
+
+	default:
+		return INBAND_NONE;
+	}
+}
+
 /**
  * phylink_pcs_neg_mode() - helper to determine PCS inband mode
  * @pl: a pointer to a &struct phylink returned from phylink_create()
@@ -1043,46 +1079,19 @@ static void phylink_pcs_neg_mode(struct phylink *pl, struct phylink_pcs *pcs,
 	unsigned int pcs_ib_caps = 0;
 	unsigned int phy_ib_caps = 0;
 	unsigned int neg_mode, mode;
-	enum {
-		INBAND_CISCO_SGMII,
-		INBAND_BASEX,
-	} type;
-
-	mode = pl->req_link_an_mode;
+	enum inband_type type;
 
-	pl->phy_ib_mode = 0;
-
-	switch (interface) {
-	case PHY_INTERFACE_MODE_SGMII:
-	case PHY_INTERFACE_MODE_QSGMII:
-	case PHY_INTERFACE_MODE_QUSGMII:
-	case PHY_INTERFACE_MODE_USXGMII:
-	case PHY_INTERFACE_MODE_10G_QXGMII:
-		/* These protocols are designed for use with a PHY which
-		 * communicates its negotiation result back to the MAC via
-		 * inband communication. Note: there exist PHYs that run
-		 * with SGMII but do not send the inband data.
-		 */
-		type = INBAND_CISCO_SGMII;
-		break;
-
-	case PHY_INTERFACE_MODE_1000BASEX:
-	case PHY_INTERFACE_MODE_2500BASEX:
-		/* 1000base-X is designed for use media-side for Fibre
-		 * connections, and thus the Autoneg bit needs to be
-		 * taken into account. We also do this for 2500base-X
-		 * as well, but drivers may not support this, so may
-		 * need to override this.
-		 */
-		type = INBAND_BASEX;
-		break;
-
-	default:
+	type = phylink_get_inband_type(interface);
+	if (type == INBAND_NONE) {
 		pl->pcs_neg_mode = PHYLINK_PCS_NEG_NONE;
-		pl->act_link_an_mode = mode;
+		pl->act_link_an_mode = pl->req_link_an_mode;
 		return;
 	}
 
+	mode = pl->req_link_an_mode;
+
+	pl->phy_ib_mode = 0;
+
 	if (pcs)
 		pcs_ib_caps = phylink_pcs_inband_caps(pcs, interface);