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 <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index b32cd20..f8a2245 100644
--- a/include/linux/ethtool.h
+++ b/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 */