igc: add preemptible queue support in mqprio

igc already supports enabling MAC Merge for FPE. This patch adds
support for preemptible queues in mqprio.

Tested preemption with mqprio by:
1. Enable FPE:
   ethtool --set-mm enp1s0 pmac-enabled on tx-enabled on verify-enabled on
2. Enable preemptible queue in mqprio:
   mqprio num_tc 4 map 0 1 2 3 0 0 0 0 0 0 0 0 0 0 0 0 \
   queues 1@0 1@1 1@2 1@3 \
   fp P P P E

Signed-off-by: Faizal Rahim <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Tested-by: Mor Bar-Gabay <[email protected]>
Signed-off-by: Tony Nguyen <[email protected]>

Author: Faizal Rahim

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

@@ -6765,6 +6765,7 @@ static int igc_tsn_enable_mqprio(struct igc_adapter *adapter,
 
 	if (!mqprio->qopt.num_tc) {
 		adapter->strict_priority_enable = false;
+		igc_fpe_clear_preempt_queue(adapter);
 		netdev_reset_tc(adapter->netdev);
 		goto apply;
 	}
@@ -6792,13 +6793,6 @@ static int igc_tsn_enable_mqprio(struct igc_adapter *adapter,
 		return -EOPNOTSUPP;
 	}
 
-	/* Preemption is not supported yet. */
-	if (mqprio->preemptible_tcs) {
-		NL_SET_ERR_MSG_MOD(mqprio->extack,
-				   "Preemption is not supported yet");
-		return -EOPNOTSUPP;
-	}
-
 	igc_save_mqprio_params(adapter, mqprio->qopt.num_tc,
 			       mqprio->qopt.offset);
 
@@ -6818,6 +6812,7 @@ static int igc_tsn_enable_mqprio(struct igc_adapter *adapter,
 		adapter->queue_per_tc[i] = i;
 
 	mqprio->qopt.hw = TC_MQPRIO_HW_OFFLOAD_TCS;
+	igc_fpe_save_preempt_queue(adapter, mqprio);
 
 apply:
 	return igc_tsn_offload_apply(adapter);

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

@@ -160,6 +160,15 @@ void igc_fpe_init(struct igc_adapter *adapter)
 	ethtool_mmsv_init(&adapter->fpe.mmsv, adapter->netdev, &igc_mmsv_ops);
 }
 
+void igc_fpe_clear_preempt_queue(struct igc_adapter *adapter)
+{
+	for (int i = 0; i < adapter->num_tx_queues; i++) {
+		struct igc_ring *tx_ring = adapter->tx_ring[i];
+
+		tx_ring->preemptible = false;
+	}
+}
+
 static u32 igc_fpe_map_preempt_tc_to_queue(const struct igc_adapter *adapter,
 					   unsigned long preemptible_tcs)
 {

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

@@ -17,6 +17,7 @@ enum igc_txd_popts_type {
 DECLARE_STATIC_KEY_FALSE(igc_fpe_enabled);
 
 void igc_fpe_init(struct igc_adapter *adapter);
+void igc_fpe_clear_preempt_queue(struct igc_adapter *adapter);
 void igc_fpe_save_preempt_queue(struct igc_adapter *adapter,
 				const struct tc_mqprio_qopt_offload *mqprio);
 u32 igc_fpe_get_supported_frag_size(u32 frag_size);