[PATCH iwl-next 4/9] igc: Add support for receiving frames with all zeroes address

[Faizal Rahim <faizal.abdul.rahim@linux.intel.com>]

From: Vinicius Costa Gomes <vinicius.gomes@intel.com>

The frame preemption verification (as defined by IEEE 802.3-2018
Section 99.4.3) handshake is done by the driver, the default
configuration of the driver is to only receive frames with the driver
address.

So, in preparation for that add a second address to the list of
acceptable addresses.

Because the frame preemption "verify_enable" toggle only affects the
transmission of verification frames, this needs to always be enabled.
As that address is invalid, the impact in practical scenarios should
be minimal. But still a bummer that we have to do this.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Faizal Rahim <faizal.abdul.rahim@linux.intel.com>
---
 drivers/net/ethernet/intel/igc/igc.h      |  1 +
 drivers/net/ethernet/intel/igc/igc_main.c | 17 +++++++++++++++++
 drivers/net/ethernet/intel/igc/igc_tsn.c  |  2 ++
 3 files changed, 20 insertions(+)

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index 34a6e4d8a652..480b54573d60 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -734,6 +734,7 @@ struct igc_nfc_rule *igc_get_nfc_rule(struct igc_adapter *adapter,
 				      u32 location);
 int igc_add_nfc_rule(struct igc_adapter *adapter, struct igc_nfc_rule *rule);
 void igc_del_nfc_rule(struct igc_adapter *adapter, struct igc_nfc_rule *rule);
+int igc_enable_empty_addr_recv(struct igc_adapter *adapter);
 struct igc_ring *igc_get_tx_ring(struct igc_adapter *adapter, int cpu);
 void igc_ptp_init(struct igc_adapter *adapter);
 void igc_ptp_reset(struct igc_adapter *adapter);
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 05146cc1b92c..3f0751a9530c 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -3962,6 +3962,23 @@ static int igc_uc_unsync(struct net_device *netdev, const unsigned char *addr)
 	return 0;
 }
 
+/**
+ * igc_enable_empty_addr_recv - Enable rx of packets with all-zeroes MAC address
+ * @adapter: Pointer to the igc_adapter structure.
+ *
+ * Frame preemption verification requires that packets with the all-zeroes
+ * MAC address are allowed to be received by IGC. This function adds the
+ * all-zeroes destination address to the list of acceptable addresses.
+ *
+ * @return: 0 on success, negative value otherwise.
+ */
+int igc_enable_empty_addr_recv(struct igc_adapter *adapter)
+{
+	u8 empty[ETH_ALEN] = { };
+
+	return igc_add_mac_filter(adapter, IGC_MAC_FILTER_TYPE_DST, empty, -1);
+}
+
 /**
  * igc_set_rx_mode - Secondary Unicast, Multicast and Promiscuous mode set
  * @netdev: network interface device structure
diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c b/drivers/net/ethernet/intel/igc/igc_tsn.c
index f0213cfce07d..5cd54ce435b9 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.c
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
@@ -434,6 +434,8 @@ int igc_tsn_reset(struct igc_adapter *adapter)
 	unsigned int new_flags;
 	int err = 0;
 
+	igc_enable_empty_addr_recv(adapter);
+
 	new_flags = igc_tsn_new_flags(adapter);
 
 	if (!(new_flags & IGC_FLAG_TSN_ANY_ENABLED))
-- 
2.25.1