[Intel-wired-lan] [PATCH next-queue v1 3/3] igc: Use ptp->aux_worker to retrieve TX timestamps

[Vinicius Costa Gomes]

ptp->aux_worker is a kthread and allows the user to set it's priority,
which is useful for workloads that time synchronization is required.

As an optimization, when the interrupt is handled try to retrieve the
timestamps "inline", if they are not, schedule the workload. This
should reduce the delay before the TX timestamp is available to
userspace.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes at intel.com>
---
 drivers/net/ethernet/intel/igc/igc.h      |  2 +-
 drivers/net/ethernet/intel/igc/igc_main.c |  7 +++++-
 drivers/net/ethernet/intel/igc/igc_ptp.c  | 29 ++++++++++++++++-------
 3 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index f0617838a16a..ce7754cb7e6f 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -237,7 +237,6 @@ struct igc_adapter {
 
 	struct ptp_clock *ptp_clock;
 	struct ptp_clock_info ptp_caps;
-	struct work_struct ptp_tx_work;
 	/* Access to ptp_tx_skb and ptp_tx_start is protected by the
 	 * ptp_tx_lock.
 	 */
@@ -651,6 +650,7 @@ int igc_ptp_set_ts_config(struct net_device *netdev, struct ifreq *ifr);
 int igc_ptp_get_ts_config(struct net_device *netdev, struct ifreq *ifr);
 void igc_ptp_tx_hang(struct igc_adapter *adapter);
 void igc_ptp_read(struct igc_adapter *adapter, struct timespec64 *ts);
+long igc_ptp_tx_work(struct ptp_clock_info *ptp);
 
 #define igc_rx_pg_size(_ring) (PAGE_SIZE << igc_rx_pg_order(_ring))
 
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 4861ad0689ed..a7775d618867 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -5226,8 +5226,13 @@ static void igc_tsync_interrupt(struct igc_adapter *adapter)
 	}
 
 	if (tsicr & IGC_TSICR_TXTS) {
+		long delay;
 		/* retrieve hardware timestamp */
-		schedule_work(&adapter->ptp_tx_work);
+		delay = igc_ptp_tx_work(&adapter->ptp_caps);
+		if (delay >= 0) {
+			/* The timestamp is not ready, schedule to check later */
+			ptp_schedule_worker(adapter->ptp_clock, delay);
+		}
 		ack |= IGC_TSICR_TXTS;
 	}
 
diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
index 0cb932b52a7b..34237464f26d 100644
--- a/drivers/net/ethernet/intel/igc/igc_ptp.c
+++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
@@ -713,24 +713,37 @@ static void igc_ptp_tx_hwtstamp(struct igc_adapter *adapter, u32 mask)
  * igc_ptp_tx_work
  * @work: pointer to work struct
  *
- * This work function polls the TSYNCTXCTL valid bit to determine when a
- * timestamp has been taken for the current stored skb.
+ * This work function polls the TSYNCTXCTL valid bit to determine when
+ * a timestamp has been taken for the current stored skb. Return a
+ * delay in case there's no timestamp ready.
  */
-static void igc_ptp_tx_work(struct work_struct *work)
+long igc_ptp_tx_work(struct ptp_clock_info *ptp)
 {
-	struct igc_adapter *adapter = container_of(work, struct igc_adapter,
-						   ptp_tx_work);
+	struct igc_adapter *adapter = container_of(ptp, struct igc_adapter,
+						   ptp_caps);
 	struct igc_hw *hw = &adapter->hw;
 	unsigned long flags;
 	u32 tsynctxctl;
+	long delay = -1;
 
 	spin_lock_irqsave(&adapter->ptp_tx_lock, flags);
 
 	tsynctxctl = rd32(IGC_TSYNCTXCTL);
+	tsynctxctl &= IGC_TSYNCTXCTL_TXTT_ANY;
+	if (!tsynctxctl) {
+		/* We got the interrupt but the timestamp is not ready
+		 * still, schedule to check later.
+		 */
+		delay = usecs_to_jiffies(1);
+		goto unlock;
+	}
 
-	igc_ptp_tx_hwtstamp(adapter, tsynctxctl & IGC_TSYNCTXCTL_TXTT_ANY);
+	igc_ptp_tx_hwtstamp(adapter, tsynctxctl);
 
+unlock:
 	spin_unlock_irqrestore(&adapter->ptp_tx_lock, flags);
+
+	return delay;
 }
 
 /**
@@ -993,6 +1006,7 @@ void igc_ptp_init(struct igc_adapter *adapter)
 		adapter->ptp_caps.n_per_out = IGC_N_PEROUT;
 		adapter->ptp_caps.n_pins = IGC_N_SDP;
 		adapter->ptp_caps.verify = igc_ptp_verify_pin;
+		adapter->ptp_caps.do_aux_work = igc_ptp_tx_work;
 
 		if (!igc_is_crosststamp_supported(adapter))
 			break;
@@ -1006,7 +1020,6 @@ void igc_ptp_init(struct igc_adapter *adapter)
 
 	spin_lock_init(&adapter->tmreg_lock);
 	spin_lock_init(&adapter->ptp_tx_lock);
-	INIT_WORK(&adapter->ptp_tx_work, igc_ptp_tx_work);
 
 	adapter->tstamp_config.rx_filter = HWTSTAMP_FILTER_NONE;
 	adapter->tstamp_config.tx_type = HWTSTAMP_TX_OFF;
@@ -1081,7 +1094,7 @@ void igc_ptp_suspend(struct igc_adapter *adapter)
 	if (!(adapter->ptp_flags & IGC_PTP_ENABLED))
 		return;
 
-	cancel_work_sync(&adapter->ptp_tx_work);
+	ptp_cancel_worker_sync(adapter->ptp_clock);
 
 	spin_lock_irqsave(&adapter->ptp_tx_lock, flags);
 
-- 
2.39.2