phylink,sfp: negotiate interface format with MAC

Negotiate the interface format with the MAC rather than requiring it to
be a fixed type specified solely by the SFP module.  This allows modules
that can work with several different interface signalling formats to
select a format compatible with the MAC - for example, a Fiber module
supporing Gigabit ethernet and faster connected to a Gigabit only MAC
needs to select the 1000BASE-X mode.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phylink.c

@@ -1584,25 +1584,14 @@ static int phylink_sfp_module_insert(void *upstream,
 	bool changed;
 	u8 port;
 
-	sfp_parse_support(pl->sfp_bus, id, support);
-	port = sfp_parse_port(pl->sfp_bus, id, support);
-	iface = sfp_parse_interface(pl->sfp_bus, id);
-
 	ASSERT_RTNL();
 
-	switch (iface) {
-	case PHY_INTERFACE_MODE_SGMII:
-	case PHY_INTERFACE_MODE_1000BASEX:
-	case PHY_INTERFACE_MODE_2500BASEX:
-	case PHY_INTERFACE_MODE_10GKR:
-		break;
-	default:
-		return -EINVAL;
-	}
+	sfp_parse_support(pl->sfp_bus, id, support);
+	port = sfp_parse_port(pl->sfp_bus, id, support);
 
 	memset(&config, 0, sizeof(config));
 	linkmode_copy(config.advertising, support);
-	config.interface = iface;
+	config.interface = PHY_INTERFACE_MODE_NA;
 	config.speed = SPEED_UNKNOWN;
 	config.duplex = DUPLEX_UNKNOWN;
 	config.pause = MLO_PAUSE_AN;
@@ -1610,6 +1599,22 @@ static int phylink_sfp_module_insert(void *upstream,
 
 	/* Ignore errors if we're expecting a PHY to attach later */
 	ret = phylink_validate(pl, support, &config);
+	if (ret) {
+		netdev_err(pl->netdev, "validation with support %*pb failed: %d\n",
+			   __ETHTOOL_LINK_MODE_MASK_NBITS, support, ret);
+		return ret;
+	}
+
+	iface = sfp_select_interface(pl->sfp_bus, id, config.advertising);
+	if (iface == PHY_INTERFACE_MODE_NA) {
+		netdev_err(pl->netdev,
+			   "selection of interface failed, advertisment %*pb\n",
+			   __ETHTOOL_LINK_MODE_MASK_NBITS, config.advertising);
+		return -EINVAL;
+	}
+
+	config.interface = iface;
+	ret = phylink_validate(pl, support, &config);
 	if (ret) {
 		netdev_err(pl->netdev, "validation of %s/%s with support %*pb failed: %d\n",
 			   phylink_an_mode_str(MLO_AN_INBAND),

drivers/net/phy/sfp-bus.c

@@ -105,68 +105,6 @@ int sfp_parse_port(struct sfp_bus *bus, const struct sfp_eeprom_id *id,
 }
 EXPORT_SYMBOL_GPL(sfp_parse_port);
 
-/**
- * sfp_parse_interface() - Parse the phy_interface_t
- * @bus: a pointer to the &struct sfp_bus structure for the sfp module
- * @id: a pointer to the module's &struct sfp_eeprom_id
- *
- * Derive the phy_interface_t mode for the information found in the
- * module's identifying EEPROM. There is no standard or defined way
- * to derive this information, so we use some heuristics.
- *
- * If the encoding is 64b66b, then the module must be >= 10G, so
- * return %PHY_INTERFACE_MODE_10GKR.
- *
- * If it's 8b10b, then it's 1G or slower. If it's definitely a fibre
- * module, return %PHY_INTERFACE_MODE_1000BASEX mode, otherwise return
- * %PHY_INTERFACE_MODE_SGMII mode.
- *
- * If the encoding is not known, return %PHY_INTERFACE_MODE_NA.
- */
-phy_interface_t sfp_parse_interface(struct sfp_bus *bus,
-				    const struct sfp_eeprom_id *id)
-{
-	phy_interface_t iface;
-
-	/* Setting the serdes link mode is guesswork: there's no field in
-	 * the EEPROM which indicates what mode should be used.
-	 *
-	 * If the module wants 64b66b, then it must be >= 10G.
-	 *
-	 * If it's a gigabit-only fiber module, it probably does not have
-	 * a PHY, so switch to 802.3z negotiation mode. Otherwise, switch
-	 * to SGMII mode (which is required to support non-gigabit speeds).
-	 */
-	switch (id->base.encoding) {
-	case SFP_ENCODING_8472_64B66B:
-		iface = PHY_INTERFACE_MODE_10GKR;
-		break;
-
-	case SFP_ENCODING_8B10B:
-		if (!id->base.e1000_base_t &&
-		    !id->base.e100_base_lx &&
-		    !id->base.e100_base_fx)
-			iface = PHY_INTERFACE_MODE_1000BASEX;
-		else
-			iface = PHY_INTERFACE_MODE_SGMII;
-		break;
-
-	default:
-		if (id->base.e1000_base_cx) {
-			iface = PHY_INTERFACE_MODE_1000BASEX;
-			break;
-		}
-
-		iface = PHY_INTERFACE_MODE_NA;
-		dev_err(bus->sfp_dev,
-			"SFP module encoding does not support 8b10b nor 64b66b\n");
-		break;
-	}
-
-	return iface;
-}
-EXPORT_SYMBOL_GPL(sfp_parse_interface);
-
 /**
  * sfp_parse_support() - Parse the eeprom id for supported link modes
  * @bus: a pointer to the &struct sfp_bus structure for the sfp module
@@ -296,6 +234,45 @@ void sfp_parse_support(struct sfp_bus *bus, const struct sfp_eeprom_id *id,
 }
 EXPORT_SYMBOL_GPL(sfp_parse_support);
 
+/**
+ * sfp_select_interface() - Select appropriate phy_interface_t mode
+ * @bus: a pointer to the &struct sfp_bus structure for the sfp module
+ * @id: a pointer to the module's &struct sfp_eeprom_id
+ * @link_modes: ethtool link modes mask
+ *
+ * Derive the phy_interface_t mode for the information found in the
+ * module's identifying EEPROM and the link modes mask. There is no
+ * standard or defined way to derive this information, so we decide
+ * based upon the link mode mask.
+ */
+phy_interface_t sfp_select_interface(struct sfp_bus *bus,
+				     const struct sfp_eeprom_id *id,
+				     unsigned long *link_modes)
+{
+	if (phylink_test(link_modes, 10000baseCR_Full) ||
+	    phylink_test(link_modes, 10000baseSR_Full) ||
+	    phylink_test(link_modes, 10000baseLR_Full) ||
+	    phylink_test(link_modes, 10000baseLRM_Full) ||
+	    phylink_test(link_modes, 10000baseER_Full))
+		return PHY_INTERFACE_MODE_10GKR;
+
+	if (phylink_test(link_modes, 2500baseX_Full))
+		return PHY_INTERFACE_MODE_2500BASEX;
+
+	if (id->base.e1000_base_t ||
+	    id->base.e100_base_lx ||
+	    id->base.e100_base_fx)
+		return PHY_INTERFACE_MODE_SGMII;
+
+	if (phylink_test(link_modes, 1000baseX_Full))
+		return PHY_INTERFACE_MODE_1000BASEX;
+
+	dev_warn(bus->sfp_dev, "Unable to ascertain link mode\n");
+
+	return PHY_INTERFACE_MODE_NA;
+}
+EXPORT_SYMBOL_GPL(sfp_select_interface);
+
 static LIST_HEAD(sfp_buses);
 static DEFINE_MUTEX(sfp_mutex);
 

include/linux/sfp.h

@@ -422,10 +422,11 @@ struct sfp_upstream_ops {
 #if IS_ENABLED(CONFIG_SFP)
 int sfp_parse_port(struct sfp_bus *bus, const struct sfp_eeprom_id *id,
 		   unsigned long *support);
-phy_interface_t sfp_parse_interface(struct sfp_bus *bus,
-				    const struct sfp_eeprom_id *id);
 void sfp_parse_support(struct sfp_bus *bus, const struct sfp_eeprom_id *id,
 		       unsigned long *support);
+phy_interface_t sfp_select_interface(struct sfp_bus *bus,
+				     const struct sfp_eeprom_id *id,
+				     unsigned long *link_modes);
 
 int sfp_get_module_info(struct sfp_bus *bus, struct ethtool_modinfo *modinfo);
 int sfp_get_module_eeprom(struct sfp_bus *bus, struct ethtool_eeprom *ee,
@@ -444,16 +445,17 @@ static inline int sfp_parse_port(struct sfp_bus *bus,
 	return PORT_OTHER;
 }
 
-static inline phy_interface_t sfp_parse_interface(struct sfp_bus *bus,
-						const struct sfp_eeprom_id *id)
+static inline void sfp_parse_support(struct sfp_bus *bus,
+				     const struct sfp_eeprom_id *id,
+				     unsigned long *support)
 {
-	return PHY_INTERFACE_MODE_NA;
 }
 
-static inline void sfp_parse_support(struct sfp_bus *bus,
+static inline phy_interface_t sfp_select_interface(struct sfp_bus *bus,
 						   const struct sfp_eeprom_id *id,
-				     unsigned long *support)
+						   unsigned long *link_modes)
 {
+	return PHY_INTERFACE_MODE_NA;
 }
 
 static inline int sfp_get_module_info(struct sfp_bus *bus,