net: phy: phy_caps: Implement link_capabilities lookup by linkmode

In several occasions, phylib needs to lookup a set of matching speed and
duplex against a given linkmode set. Instead of relying on the
phy_settings array and thus iterate over the whole linkmodes list, use
the link_capabilities array to lookup these matches, as we aren't
interested in the actual link setting that matches but rather the speed
and duplex for that setting.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20250307173611.129125-7-maxime.chevallier@bootlin.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/phy/phy-caps.h

@@ -45,5 +45,10 @@ size_t phy_caps_speeds(unsigned int *speeds, size_t size,
 void phy_caps_linkmode_max_speed(u32 max_speed, unsigned long *linkmodes);
 bool phy_caps_valid(int speed, int duplex, const unsigned long *linkmodes);
 
+const struct link_capabilities *
+phy_caps_lookup_by_linkmode(const unsigned long *linkmodes);
+
+const struct link_capabilities *
+phy_caps_lookup_by_linkmode_rev(const unsigned long *linkmodes, bool fdx_only);
 
 #endif /* __PHY_CAPS_H */

drivers/net/phy/phy-core.c

@@ -469,16 +469,15 @@ EXPORT_SYMBOL_GPL(phy_resolve_aneg_pause);
 void phy_resolve_aneg_linkmode(struct phy_device *phydev)
 {
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(common);
-	int i;
+	const struct link_capabilities *c;
 
 	linkmode_and(common, phydev->lp_advertising, phydev->advertising);
 
-	for (i = 0; i < ARRAY_SIZE(settings); i++)
-		if (test_bit(settings[i].bit, common)) {
-			phydev->speed = settings[i].speed;
-			phydev->duplex = settings[i].duplex;
-			break;
-		}
+	c = phy_caps_lookup_by_linkmode(common);
+	if (c) {
+		phydev->speed = c->speed;
+		phydev->duplex = c->duplex;
+	}
 
 	phy_resolve_aneg_pause(phydev);
 }
@@ -496,7 +495,8 @@ EXPORT_SYMBOL_GPL(phy_resolve_aneg_linkmode);
 void phy_check_downshift(struct phy_device *phydev)
 {
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(common);
-	int i, speed = SPEED_UNKNOWN;
+	const struct link_capabilities *c;
+	int speed = SPEED_UNKNOWN;
 
 	phydev->downshifted_rate = 0;
 
@@ -506,11 +506,9 @@ void phy_check_downshift(struct phy_device *phydev)
 
 	linkmode_and(common, phydev->lp_advertising, phydev->advertising);
 
-	for (i = 0; i < ARRAY_SIZE(settings); i++)
-		if (test_bit(settings[i].bit, common)) {
-			speed = settings[i].speed;
-			break;
-		}
+	c = phy_caps_lookup_by_linkmode(common);
+	if (c)
+		speed = c->speed;
 
 	if (speed == SPEED_UNKNOWN || phydev->speed >= speed)
 		return;
@@ -524,17 +522,13 @@ void phy_check_downshift(struct phy_device *phydev)
 static int phy_resolve_min_speed(struct phy_device *phydev, bool fdx_only)
 {
 	__ETHTOOL_DECLARE_LINK_MODE_MASK(common);
-	int i = ARRAY_SIZE(settings);
+	const struct link_capabilities *c;
 
 	linkmode_and(common, phydev->lp_advertising, phydev->advertising);
 
-	while (--i >= 0) {
-		if (test_bit(settings[i].bit, common)) {
-			if (fdx_only && settings[i].duplex != DUPLEX_FULL)
-				continue;
-			return settings[i].speed;
-		}
-	}
+	c = phy_caps_lookup_by_linkmode_rev(common, fdx_only);
+	if (c)
+		return c->speed;
 
 	return SPEED_UNKNOWN;
 }

drivers/net/phy/phy_caps.c

@@ -125,6 +125,51 @@ size_t phy_caps_speeds(unsigned int *speeds, size_t size,
 	return count;
 }
 
+/**
+ * phy_caps_lookup_by_linkmode() - Lookup the fastest matching link_capabilities
+ * @linkmodes: Linkmodes to match against
+ *
+ * Returns: The highest-speed link_capabilities that intersects the given
+ *	    linkmodes. In case several DUPLEX_ options exist at that speed,
+ *	    DUPLEX_FULL is matched first. NULL is returned if no match.
+ */
+const struct link_capabilities *
+phy_caps_lookup_by_linkmode(const unsigned long *linkmodes)
+{
+	struct link_capabilities *lcap;
+
+	for_each_link_caps_desc_speed(lcap)
+		if (linkmode_intersects(lcap->linkmodes, linkmodes))
+			return lcap;
+
+	return NULL;
+}
+
+/**
+ * phy_caps_lookup_by_linkmode_rev() - Lookup the slowest matching link_capabilities
+ * @linkmodes: Linkmodes to match against
+ * @fdx_only: Full duplex match only when set
+ *
+ * Returns: The lowest-speed link_capabilities that intersects the given
+ *	    linkmodes. When set, fdx_only will ignore half-duplex matches.
+ *	    NULL is returned if no match.
+ */
+const struct link_capabilities *
+phy_caps_lookup_by_linkmode_rev(const unsigned long *linkmodes, bool fdx_only)
+{
+	struct link_capabilities *lcap;
+
+	for_each_link_caps_asc_speed(lcap) {
+		if (fdx_only && lcap->duplex != DUPLEX_FULL)
+			continue;
+
+		if (linkmode_intersects(lcap->linkmodes, linkmodes))
+			return lcap;
+	}
+
+	return NULL;
+}
+
 /**
  * phy_caps_linkmode_max_speed() - Clamp a linkmodes set to a max speed
  * @max_speed: Speed limit for the linkmode set