[PATCH iwl-next 7/9] igc: Add support for preemptible traffic class in taprio

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

Set queue as preemptible or express for taprio.
This will eventually set queue-specific preemptible field in TXQCTL
register.

A preemptible queue can only be set if it satisfies the conditions in
igc_fpe_is_tx_preempt_allowed(), including the verification handshake
condition. However, the handshake is optional, as users can disable the
"verify_enabled" field, which the function also handles.

Verified that the correct preemptible hardware queue is set using the
following commands:

a) 1:1 TC-to-Queue Mapping
   $ sudo tc qdisc replace dev enp1s0 parent root handle 100 \
     taprio 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 base-time 0 sched-entry S F 100000 \
     fp E E P P

b) Non-1:1 TC-to-Queue Mapping
   $ sudo tc qdisc replace  dev enp1s0 parent root handle 100 \
     taprio num_tc 3 map 0 1 1 1 2 0 0 0 0 0 0 0 0 0 0 0
     queues 2@0 1@2 1@3
     fp E P P

Co-developed-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
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         |  2 +-
 drivers/net/ethernet/intel/igc/igc_defines.h |  1 +
 drivers/net/ethernet/intel/igc/igc_main.c    | 36 ++++++++++++++++++++
 drivers/net/ethernet/intel/igc/igc_tsn.c     | 15 ++++++++
 drivers/net/ethernet/intel/igc/igc_tsn.h     |  1 +
 5 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index 56a426765be7..fc1960925e28 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -192,7 +192,7 @@ struct igc_ring {
 	bool launchtime_enable;         /* true if LaunchTime is enabled */
 	ktime_t last_tx_cycle;          /* end of the cycle with a launchtime transmission */
 	ktime_t last_ff_cycle;          /* Last cycle with an active first flag */
-
+	bool preemptible;               /* True if not express */
 	u32 start_time;
 	u32 end_time;
 	u32 max_sdu;
diff --git a/drivers/net/ethernet/intel/igc/igc_defines.h b/drivers/net/ethernet/intel/igc/igc_defines.h
index ba96776d5854..33c2e4ce7cc8 100644
--- a/drivers/net/ethernet/intel/igc/igc_defines.h
+++ b/drivers/net/ethernet/intel/igc/igc_defines.h
@@ -557,6 +557,7 @@
 #define IGC_TXQCTL_QUEUE_MODE_LAUNCHT	0x00000001
 #define IGC_TXQCTL_STRICT_CYCLE		0x00000002
 #define IGC_TXQCTL_STRICT_END		0x00000004
+#define IGC_TXQCTL_PREEMPTIBLE		0x00000008
 #define IGC_TXQCTL_QAV_SEL_MASK		0x000000C0
 #define IGC_TXQCTL_QAV_SEL_CBS0		0x00000080
 #define IGC_TXQCTL_QAV_SEL_CBS1		0x000000C0
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index e184959ef218..2787a91965d1 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -6216,6 +6216,39 @@ static bool is_base_time_past(ktime_t base_time, const struct timespec64 *now)
 	return timespec64_compare(now, &b) > 0;
 }
 
+static u32 igc_map_tc_to_queue(const struct igc_adapter *adapter,
+			       unsigned long preemptible_tcs)
+{
+	struct net_device *dev = adapter->netdev;
+	u32 i, queue = 0;
+
+	for (i = 0; i < dev->num_tc; i++) {
+		u32 offset, count;
+
+		if (!(preemptible_tcs & BIT(i)))
+			continue;
+
+		offset = dev->tc_to_txq[i].offset;
+		count = dev->tc_to_txq[i].count;
+		queue |= GENMASK(offset + count - 1, offset);
+	}
+
+	return queue;
+}
+
+static void igc_save_preempt_queue(struct igc_adapter *adapter,
+				   const struct tc_mqprio_qopt_offload *mqprio)
+{
+	u32 preemptible_queue = igc_map_tc_to_queue(adapter,
+						    mqprio->preemptible_tcs);
+
+	for (int i = 0; i < adapter->num_tx_queues; i++) {
+		struct igc_ring *tx_ring = adapter->tx_ring[i];
+
+		tx_ring->preemptible = preemptible_queue & BIT(i);
+	}
+}
+
 static bool validate_schedule(struct igc_adapter *adapter,
 			      const struct tc_taprio_qopt_offload *qopt)
 {
@@ -6302,6 +6335,7 @@ static int igc_qbv_clear_schedule(struct igc_adapter *adapter)
 		ring->start_time = 0;
 		ring->end_time = NSEC_PER_SEC;
 		ring->max_sdu = 0;
+		ring->preemptible = false;
 	}
 
 	spin_lock_irqsave(&adapter->qbv_tx_lock, flags);
@@ -6458,6 +6492,8 @@ static int igc_save_qbv_schedule(struct igc_adapter *adapter,
 			ring->max_sdu = 0;
 	}
 
+	igc_save_preempt_queue(adapter, &qopt->mqprio);
+
 	return 0;
 }
 
diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.c b/drivers/net/ethernet/intel/igc/igc_tsn.c
index 3d39be2219f3..efd2a9f676d8 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.c
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.c
@@ -209,6 +209,17 @@ void igc_fpe_init(struct fpe_t *fpe)
 	fpe->tx_min_frag_size = IGC_TX_MIN_FRAG_SIZE;
 }
 
+static bool igc_fpe_is_verifed(const struct fpe_t *fpe)
+{
+	return (fpe->verify_enabled && fpe->verify_state == VERIFIED);
+}
+
+bool igc_fpe_is_tx_preempt_allowed(const struct fpe_t *fpe)
+{
+	return (fpe->pmac_enabled && fpe->tx_enabled &&
+		(igc_fpe_is_verifed(fpe) || !fpe->verify_enabled));
+}
+
 void igc_fpe_verify_enabled_changed(struct fpe_t *fpe)
 {
 	if (fpe->verify_enabled && fpe->tx_enabled) {
@@ -539,6 +550,10 @@ static int igc_tsn_enable_offload(struct igc_adapter *adapter)
 		if (ring->launchtime_enable)
 			txqctl |= IGC_TXQCTL_QUEUE_MODE_LAUNCHT;
 
+		if (igc_fpe_is_tx_preempt_allowed(&adapter->fpe) &&
+		    ring->preemptible)
+			txqctl |= IGC_TXQCTL_PREEMPTIBLE;
+
 		/* Skip configuring CBS for Q2 and Q3 */
 		if (i > 1)
 			goto skip_cbs;
diff --git a/drivers/net/ethernet/intel/igc/igc_tsn.h b/drivers/net/ethernet/intel/igc/igc_tsn.h
index f3d83fbbd1f4..2b67ecae99c9 100644
--- a/drivers/net/ethernet/intel/igc/igc_tsn.h
+++ b/drivers/net/ethernet/intel/igc/igc_tsn.h
@@ -14,6 +14,7 @@
 
 int igc_fpe_get_smd_type(__le32 status_error);
 void igc_fpe_init(struct fpe_t *fpe);
+bool igc_fpe_is_tx_preempt_allowed(const struct fpe_t *fpe);
 bool igc_fpe_is_verify_or_response(int smd_type, unsigned int size);
 void igc_fpe_preprocess_verify_response(struct fpe_t *fpe, int smd_type);
 void igc_fpe_verify_enabled_changed(struct fpe_t *fpe);
-- 
2.25.1