igc: Add support for CBS offloading

Implement support for Credit-based shaper(CBS) Qdisc hardware
offload mode in the driver. There are two sets of IEEE802.1Qav
(CBS) HW logic in i225 controller and this patch supports
enabling them in the top two priority TX queues.

Driver implemented as recommended by Foxville External
Architecture Specification v0.993. Idleslope and Hi-credit are
the CBS tunable parameters for i225 NIC, programmed in TQAVCC
and TQAVHC registers respectively.

In-order for IEEE802.1Qav (CBS) algorithm to work as intended
and provide BW reservation CBS should be enabled in highest
priority queue first. If we enable CBS on any of low priority
queues, the traffic in high priority queue does not allow low
priority queue to be selected for transmission and bandwidth
reservation is not guaranteed.

Signed-off-by: Aravindhan Gunasekaran <aravindhan.gunasekaran@intel.com>
Signed-off-by: Mallikarjuna Chilakala <mallikarjuna.chilakala@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

1 files changed, 71 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 2e5c9b5a57d1..b877efae61df 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -5904,6 +5904,74 @@ static int igc_tsn_enable_qbv_scheduling(struct igc_adapter *adapter,
 	return igc_tsn_offload_apply(adapter);
 }
 
+static int igc_save_cbs_params(struct igc_adapter *adapter, int queue,
+			       bool enable, int idleslope, int sendslope,
+			       int hicredit, int locredit)
+{
+	bool cbs_status[IGC_MAX_SR_QUEUES] = { false };
+	struct net_device *netdev = adapter->netdev;
+	struct igc_ring *ring;
+	int i;
+
+	/* i225 has two sets of credit-based shaper logic.
+	 * Supporting it only on the top two priority queues
+	 */
+	if (queue < 0 || queue > 1)
+		return -EINVAL;
+
+	ring = adapter->tx_ring[queue];
+
+	for (i = 0; i < IGC_MAX_SR_QUEUES; i++)
+		if (adapter->tx_ring[i])
+			cbs_status[i] = adapter->tx_ring[i]->cbs_enable;
+
+	/* CBS should be enabled on the highest priority queue first in order
+	 * for the CBS algorithm to operate as intended.
+	 */
+	if (enable) {
+		if (queue == 1 && !cbs_status[0]) {
+			netdev_err(netdev,
+				   "Enabling CBS on queue1 before queue0\n");
+			return -EINVAL;
+		}
+	} else {
+		if (queue == 0 && cbs_status[1]) {
+			netdev_err(netdev,
+				   "Disabling CBS on queue0 before queue1\n");
+			return -EINVAL;
+		}
+	}
+
+	ring->cbs_enable = enable;
+	ring->idleslope = idleslope;
+	ring->sendslope = sendslope;
+	ring->hicredit = hicredit;
+	ring->locredit = locredit;
+
+	return 0;
+}
+
+static int igc_tsn_enable_cbs(struct igc_adapter *adapter,
+			      struct tc_cbs_qopt_offload *qopt)
+{
+	struct igc_hw *hw = &adapter->hw;
+	int err;
+
+	if (hw->mac.type != igc_i225)
+		return -EOPNOTSUPP;
+
+	if (qopt->queue < 0 || qopt->queue > 1)
+		return -EINVAL;
+
+	err = igc_save_cbs_params(adapter, qopt->queue, qopt->enable,
+				  qopt->idleslope, qopt->sendslope,
+				  qopt->hicredit, qopt->locredit);
+	if (err)
+		return err;
+
+	return igc_tsn_offload_apply(adapter);
+}
+
 static int igc_setup_tc(struct net_device *dev, enum tc_setup_type type,
 			void *type_data)
 {
@@ -5916,6 +5984,9 @@ static int igc_setup_tc(struct net_device *dev, enum tc_setup_type type,
 	case TC_SETUP_QDISC_ETF:
 		return igc_tsn_enable_launchtime(adapter, type_data);
 
+	case TC_SETUP_QDISC_CBS:
+		return igc_tsn_enable_cbs(adapter, type_data);
+
 	default:
 		return -EOPNOTSUPP;
 	}