igc: Add support for taprio offloading

Adds support for translating taprio schedules into i225 cycles. This
will allow schedules to run in the hardware, making the schedules
enforcement more precise and saving CPU time.

Right now, the only simple schedules are allowed, complex schedules are
rejected. "simple" in this context are schedules that each HW queue is
opened and closed only once in each cycle.

Changing schedules is still not supported as well.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Reviewed-by: Andre Guedes <andre.guedes@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 140 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c b/drivers/net/ethernet/intel/igc/igc_tsn.c
new file mode 100644
index 000000000000..257fe970afe8
--- /dev/null
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c)  2019 Intel Corporation */
+
+#include "igc.h"
+#include "igc_tsn.h"
+
+/* Returns the TSN specific registers to their default values after
+ * TSN offloading is disabled.
+ */
+static int igc_tsn_disable_offload(struct igc_adapter *adapter)
+{
+	struct igc_hw *hw = &adapter->hw;
+	u32 tqavctrl;
+	int i;
+
+	if (!(adapter->flags & IGC_FLAG_TSN_QBV_ENABLED))
+		return 0;
+
+	adapter->cycle_time = 0;
+
+	wr32(IGC_TXPBS, I225_TXPBSIZE_DEFAULT);
+	wr32(IGC_DTXMXPKTSZ, IGC_DTXMXPKTSZ_DEFAULT);
+
+	tqavctrl = rd32(IGC_TQAVCTRL);
+	tqavctrl &= ~(IGC_TQAVCTRL_TRANSMIT_MODE_TSN |
+		      IGC_TQAVCTRL_ENHANCED_QAV);
+	wr32(IGC_TQAVCTRL, tqavctrl);
+
+	for (i = 0; i < adapter->num_tx_queues; i++) {
+		struct igc_ring *ring = adapter->tx_ring[i];
+
+		ring->start_time = 0;
+		ring->end_time = 0;
+		ring->launchtime_enable = false;
+
+		wr32(IGC_TXQCTL(i), 0);
+		wr32(IGC_STQT(i), 0);
+		wr32(IGC_ENDQT(i), NSEC_PER_SEC);
+	}
+
+	wr32(IGC_QBVCYCLET_S, NSEC_PER_SEC);
+	wr32(IGC_QBVCYCLET, NSEC_PER_SEC);
+
+	adapter->flags &= ~IGC_FLAG_TSN_QBV_ENABLED;
+
+	return 0;
+}
+
+static int igc_tsn_enable_offload(struct igc_adapter *adapter)
+{
+	struct igc_hw *hw = &adapter->hw;
+	u32 tqavctrl, baset_l, baset_h;
+	u32 sec, nsec, cycle;
+	ktime_t base_time, systim;
+	int i;
+
+	if (adapter->flags & IGC_FLAG_TSN_QBV_ENABLED)
+		return 0;
+
+	cycle = adapter->cycle_time;
+	base_time = adapter->base_time;
+
+	wr32(IGC_TSAUXC, 0);
+	wr32(IGC_DTXMXPKTSZ, IGC_DTXMXPKTSZ_TSN);
+	wr32(IGC_TXPBS, IGC_TXPBSIZE_TSN);
+
+	tqavctrl = rd32(IGC_TQAVCTRL);
+	tqavctrl |= IGC_TQAVCTRL_TRANSMIT_MODE_TSN | IGC_TQAVCTRL_ENHANCED_QAV;
+	wr32(IGC_TQAVCTRL, tqavctrl);
+
+	wr32(IGC_QBVCYCLET_S, cycle);
+	wr32(IGC_QBVCYCLET, cycle);
+
+	for (i = 0; i < adapter->num_tx_queues; i++) {
+		struct igc_ring *ring = adapter->tx_ring[i];
+		u32 txqctl = 0;
+
+		wr32(IGC_STQT(i), ring->start_time);
+		wr32(IGC_ENDQT(i), ring->end_time);
+
+		if (adapter->base_time) {
+			/* If we have a base_time we are in "taprio"
+			 * mode and we need to be strict about the
+			 * cycles: only transmit a packet if it can be
+			 * completed during that cycle.
+			 */
+			txqctl |= IGC_TXQCTL_STRICT_CYCLE |
+				IGC_TXQCTL_STRICT_END;
+		}
+
+		wr32(IGC_TXQCTL(i), txqctl);
+	}
+
+	nsec = rd32(IGC_SYSTIML);
+	sec = rd32(IGC_SYSTIMH);
+
+	systim = ktime_set(sec, nsec);
+
+	if (ktime_compare(systim, base_time) > 0) {
+		s64 n;
+
+		n = div64_s64(ktime_sub_ns(systim, base_time), cycle);
+		base_time = ktime_add_ns(base_time, (n + 1) * cycle);
+	}
+
+	baset_h = div_s64_rem(base_time, NSEC_PER_SEC, &baset_l);
+
+	wr32(IGC_BASET_H, baset_h);
+	wr32(IGC_BASET_L, baset_l);
+
+	adapter->flags |= IGC_FLAG_TSN_QBV_ENABLED;
+
+	return 0;
+}
+
+int igc_tsn_offload_apply(struct igc_adapter *adapter)
+{
+	bool is_any_enabled = adapter->base_time;
+
+	if (!(adapter->flags & IGC_FLAG_TSN_QBV_ENABLED) && !is_any_enabled)
+		return 0;
+
+	if (!is_any_enabled) {
+		int err = igc_tsn_disable_offload(adapter);
+
+		if (err < 0)
+			return err;
+
+		/* The BASET registers aren't cleared when writing
+		 * into them, force a reset if the interface is
+		 * running.
+		 */
+		if (netif_running(adapter->netdev))
+			schedule_work(&adapter->reset_task);
+
+		return 0;
+	}
+
+	return igc_tsn_enable_offload(adapter);
+}