igc: offload queue max SDU from tc-taprio

Add support for configuring the max SDU for each Tx queue.
If not specified, keep the default.
Signed-off-by: Tan Tee Min <tee.min.tan@linux.intel.com>
Signed-off-by: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igc/igc.h

@@ -99,6 +99,7 @@ struct igc_ring {
 
 	u32 start_time;
 	u32 end_time;
+	u32 max_sdu;
 
 	/* CBS parameters */
 	bool cbs_enable;                /* indicates if CBS is enabled */

drivers/net/ethernet/intel/igc/igc_hw.h

@@ -273,6 +273,7 @@ struct igc_hw_stats {
 	u64 o2bspc;
 	u64 b2ospc;
 	u64 b2ogprc;
+	u64 txdrop;
 };
 
 struct net_device *igc_get_hw_dev(struct igc_hw *hw);

drivers/net/ethernet/intel/igc/igc_main.c

@@ -1501,6 +1501,7 @@ static int igc_tso(struct igc_ring *tx_ring,
 static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
 				       struct igc_ring *tx_ring)
 {
+	struct igc_adapter *adapter = netdev_priv(tx_ring->netdev);
 	bool first_flag = false, insert_empty = false;
 	u16 count = TXD_USE_COUNT(skb_headlen(skb));
 	__be16 protocol = vlan_get_protocol(skb);
@@ -1563,9 +1564,19 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb,
 	first->bytecount = skb->len;
 	first->gso_segs = 1;
 
-	if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) {
-		struct igc_adapter *adapter = netdev_priv(tx_ring->netdev);
+	if (tx_ring->max_sdu > 0) {
+		u32 max_sdu = 0;
+
+		max_sdu = tx_ring->max_sdu +
+			  (skb_vlan_tagged(first->skb) ? VLAN_HLEN : 0);
 
+		if (first->bytecount > max_sdu) {
+			adapter->stats.txdrop++;
+			goto out_drop;
+		}
+	}
+
+	if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) {
 		/* FIXME: add support for retrieving timestamps from
 		 * the other timer registers before skipping the
 		 * timestamping request.
@@ -4920,7 +4931,8 @@ void igc_update_stats(struct igc_adapter *adapter)
 	net_stats->tx_window_errors = adapter->stats.latecol;
 	net_stats->tx_carrier_errors = adapter->stats.tncrs;
 
-	/* Tx Dropped needs to be maintained elsewhere */
+	/* Tx Dropped */
+	net_stats->tx_dropped = adapter->stats.txdrop;
 
 	/* Management Stats */
 	adapter->stats.mgptc += rd32(IGC_MGTPTC);
@@ -6056,6 +6068,7 @@ static int igc_tsn_clear_schedule(struct igc_adapter *adapter)
 
 		ring->start_time = 0;
 		ring->end_time = NSEC_PER_SEC;
+		ring->max_sdu = 0;
 	}
 
 	return 0;
@@ -6139,6 +6152,16 @@ static int igc_save_qbv_schedule(struct igc_adapter *adapter,
 		}
 	}
 
+	for (i = 0; i < adapter->num_tx_queues; i++) {
+		struct igc_ring *ring = adapter->tx_ring[i];
+		struct net_device *dev = adapter->netdev;
+
+		if (qopt->max_sdu[i])
+			ring->max_sdu = qopt->max_sdu[i] + dev->hard_header_len;
+		else
+			ring->max_sdu = 0;
+	}
+
 	return 0;
 }
 
@@ -6237,8 +6260,10 @@ static int igc_tc_query_caps(struct igc_adapter *adapter,
 
 		caps->broken_mqprio = true;
 
-		if (hw->mac.type == igc_i225)
+		if (hw->mac.type == igc_i225) {
+			caps->supports_queue_max_sdu = true;
 			caps->gate_mask_per_txq = true;
+		}
 
 		return 0;
 	}