net: Allow network devices to have PHY statistics

Add a new callback: get_ethtool_phy_stats() which allows network device
drivers not making use of the PHY library to return PHY statistics.
Update ethtool_get_phy_stats(), __ethtool_get_sset_count() and
__ethtool_get_strings() accordingly to interogate the network device
about ETH_SS_PHY_STATS.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/ethtool.h

@@ -312,6 +312,9 @@ bool ethtool_convert_link_mode_to_legacy_u32(u32 *legacy_u32,
  *	by kernel. Returns a negative error code or zero.
  * @get_fecparam: Get the network device Forward Error Correction parameters.
  * @set_fecparam: Set the network device Forward Error Correction parameters.
+ * @get_ethtool_phy_stats: Return extended statistics about the PHY device.
+ *	This is only useful if the device maintains PHY statistics and
+ *	cannot use the standard PHY library helpers.
  *
  * All operations are optional (i.e. the function pointer may be set
  * to %NULL) and callers must take this into account.  Callers must
@@ -407,5 +410,7 @@ struct ethtool_ops {
 				      struct ethtool_fecparam *);
 	int	(*set_fecparam)(struct net_device *,
 				      struct ethtool_fecparam *);
+	void	(*get_ethtool_phy_stats)(struct net_device *,
+					 struct ethtool_stats *, u64 *);
 };
 #endif /* _LINUX_ETHTOOL_H */

net/core/ethtool.c

@@ -227,12 +227,9 @@ static int __ethtool_get_sset_count(struct net_device *dev, int sset)
 	if (sset == ETH_SS_PHY_TUNABLES)
 		return ARRAY_SIZE(phy_tunable_strings);
 
-	if (sset == ETH_SS_PHY_STATS) {
-		if (dev->phydev)
+	if (sset == ETH_SS_PHY_STATS && dev->phydev &&
+	    !ops->get_ethtool_phy_stats)
 		return phy_ethtool_get_sset_count(dev->phydev);
-		else
-			return -EOPNOTSUPP;
-	}
 
 	if (ops->get_sset_count && ops->get_strings)
 		return ops->get_sset_count(dev, sset);
@@ -255,12 +252,10 @@ static void __ethtool_get_strings(struct net_device *dev,
 		memcpy(data, tunable_strings, sizeof(tunable_strings));
 	else if (stringset == ETH_SS_PHY_TUNABLES)
 		memcpy(data, phy_tunable_strings, sizeof(phy_tunable_strings));
-	else if (stringset == ETH_SS_PHY_STATS) {
-		if (dev->phydev)
+	else if (stringset == ETH_SS_PHY_STATS && dev->phydev &&
+		 !ops->get_ethtool_phy_stats)
 		phy_ethtool_get_strings(dev->phydev, data);
 	else
-			return;
-	} else
 		/* ops->get_strings is valid because checked earlier */
 		ops->get_strings(dev, stringset, data);
 }
@@ -1972,15 +1967,19 @@ static int ethtool_get_stats(struct net_device *dev, void __user *useraddr)
 
 static int ethtool_get_phy_stats(struct net_device *dev, void __user *useraddr)
 {
-	struct ethtool_stats stats;
+	const struct ethtool_ops *ops = dev->ethtool_ops;
 	struct phy_device *phydev = dev->phydev;
+	struct ethtool_stats stats;
 	u64 *data;
 	int ret, n_stats;
 
-	if (!phydev)
+	if (!phydev && (!ops->get_ethtool_phy_stats || !ops->get_sset_count))
 		return -EOPNOTSUPP;
 
+	if (dev->phydev && !ops->get_ethtool_phy_stats)
 		n_stats = phy_ethtool_get_sset_count(dev->phydev);
+	else
+		n_stats = ops->get_sset_count(dev, ETH_SS_PHY_STATS);
 	if (n_stats < 0)
 		return n_stats;
 	if (n_stats > S32_MAX / sizeof(u64))
@@ -1995,9 +1994,13 @@ static int ethtool_get_phy_stats(struct net_device *dev, void __user *useraddr)
 	if (n_stats && !data)
 		return -ENOMEM;
 
+	if (dev->phydev && !ops->get_ethtool_phy_stats) {
 		ret = phy_ethtool_get_stats(dev->phydev, &stats, data);
 		if (ret < 0)
 			return ret;
+	} else {
+		ops->get_ethtool_phy_stats(dev, &stats, data);
+	}
 
 	ret = -EFAULT;
 	if (copy_to_user(useraddr, &stats, sizeof(stats)))