net: ethtool: netlink: retrieve stats from multiple sources (eMAC, pMAC)

IEEE 802.3-2018 clause 99 defines a MAC Merge sublayer which contains an
Express MAC and a Preemptible MAC. Both MACs are hidden to higher and
lower layers and visible as a single MAC (packet classification to eMAC
or pMAC on TX is done based on priority; classification on RX is done
based on SFD).

For devices which support a MAC Merge sublayer, it is desirable to
retrieve individual packet counters from the eMAC and the pMAC, as well
as aggregate statistics (their sum).

Introduce a new ETHTOOL_A_STATS_SRC attribute which is part of the
policy of ETHTOOL_MSG_STATS_GET and, and an ETHTOOL_A_PAUSE_STATS_SRC
which is part of the policy of ETHTOOL_MSG_PAUSE_GET (accepted when
ETHTOOL_FLAG_STATS is set in the common ethtool header). Both of these
take values from enum ethtool_mac_stats_src, defaulting to "aggregate"
in the absence of the attribute.

Existing drivers do not need to pay attention to this enum which was
added to all driver-facing structures, just the ones which report the
MAC merge layer as supported.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 0 deletions

diff --git a/net/ethtool/mm.c b/net/ethtool/mm.c
index 76b209ad53d2..809d196665c6 100644
--- a/net/ethtool/mm.c
+++ b/net/ethtool/mm.c
@@ -253,3 +253,19 @@ out_dev_put:
 	ethnl_parse_header_dev_put(&req_info);
 	return ret;
 }
+
+/* Returns whether a given device supports the MAC merge layer
+ * (has an eMAC and a pMAC). Must be called under rtnl_lock() and
+ * ethnl_ops_begin().
+ */
+bool __ethtool_dev_mm_supported(struct net_device *dev)
+{
+	const struct ethtool_ops *ops = dev->ethtool_ops;
+	struct ethtool_mm_state state = {};
+	int ret = -EOPNOTSUPP;
+
+	if (ops && ops->get_mm)
+		ret = ops->get_mm(dev, &state);
+
+	return !!ret;
+}