net: phylink: split out PHY validation from phylink_bringup_phy()

When bringing up a PHY, we need to work out which ethtool link modes it
should support and advertise. Clause 22 PHYs operate in a single
interface mode, which can be easily dealt with. However, clause 45 PHYs
tend to switch interface mode depending on the media. We need more
flexible validation at this point, so this patch splits out that code
in preparation to changing it.

Tested-by: Luo Jie <quic_luoj@quicinc.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/E1r6VIQ-00DDM9-LK@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Russell King (Oracle)

drivers/net/phy/phylink.c

@@ -1760,6 +1760,35 @@ static void phylink_phy_change(struct phy_device *phydev, bool up)
 		    phylink_pause_to_str(pl->phy_state.pause));
 }
 
+static int phylink_validate_phy(struct phylink *pl, struct phy_device *phy,
+				unsigned long *supported,
+				struct phylink_link_state *state)
+{
+	/* Check whether we would use rate matching for the proposed interface
+	 * mode.
+	 */
+	state->rate_matching = phy_get_rate_matching(phy, state->interface);
+
+	/* Clause 45 PHYs may switch their Serdes lane between, e.g. 10GBASE-R,
+	 * 5GBASE-R, 2500BASE-X and SGMII if they are not using rate matching.
+	 * For some interface modes (e.g. RXAUI, XAUI and USXGMII) switching
+	 * their Serdes is either unnecessary or not reasonable.
+	 *
+	 * For these which switch interface modes, we really need to know which
+	 * interface modes the PHY supports to properly work out which ethtool
+	 * linkmodes can be supported. For now, as a work-around, we validate
+	 * against all interface modes, which may lead to more ethtool link
+	 * modes being advertised than are actually supported.
+	 */
+	if (phy->is_c45 && state->rate_matching == RATE_MATCH_NONE &&
+	    state->interface != PHY_INTERFACE_MODE_RXAUI &&
+	    state->interface != PHY_INTERFACE_MODE_XAUI &&
+	    state->interface != PHY_INTERFACE_MODE_USXGMII)
+		state->interface = PHY_INTERFACE_MODE_NA;
+
+	return phylink_validate(pl, supported, state);
+}
+
 static int phylink_bringup_phy(struct phylink *pl, struct phy_device *phy,
 			       phy_interface_t interface)
 {
@@ -1780,32 +1809,9 @@ 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 = interface;
 
-	/* Check whether we would use rate matching for the proposed interface
-	 * mode.
-	 */
-	config.rate_matching = phy_get_rate_matching(phy, interface);
-
-	/* Clause 45 PHYs may switch their Serdes lane between, e.g. 10GBASE-R,
-	 * 5GBASE-R, 2500BASE-X and SGMII if they are not using rate matching.
-	 * For some interface modes (e.g. RXAUI, XAUI and USXGMII) switching
-	 * their Serdes is either unnecessary or not reasonable.
-	 *
-	 * For these which switch interface modes, we really need to know which
-	 * interface modes the PHY supports to properly work out which ethtool
-	 * linkmodes can be supported. For now, as a work-around, we validate
-	 * against all interface modes, which may lead to more ethtool link
-	 * modes being advertised than are actually supported.
-	 */
-	if (phy->is_c45 && config.rate_matching == RATE_MATCH_NONE &&
-	    interface != PHY_INTERFACE_MODE_RXAUI &&
-	    interface != PHY_INTERFACE_MODE_XAUI &&
-	    interface != PHY_INTERFACE_MODE_USXGMII)
-		config.interface = PHY_INTERFACE_MODE_NA;
-	else
-		config.interface = interface;
-
-	ret = phylink_validate(pl, supported, &config);
+	ret = phylink_validate_phy(pl, phy, supported, &config);
 	if (ret) {
 		phylink_warn(pl, "validation of %s with support %*pb and advertisement %*pb failed: %pe\n",
 			     phy_modes(config.interface),