sfc: handle TX timestamps in the normal data path

Before this work, TX timestamping is done by sending each SKB to the MC.
On the 8000 series (Medford1) we have high speed timestamping via the
 MAC, which means we can use normal TX queues for this without a
 significant drop in bandwidth.  On the X2000 series (Medford2) support
 for transmitting via the MC is removed, so the new way must be used.

This patch enables timestamping on a TX queue, if requested.
It also enhances TX event handling to process the extra completion events,
 and puts the time in the SKB.

Signed-off-by: Martin Habets <mhabets@solarflare.com>
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 79 insertions, 8 deletions

diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index 03ec2cc1eab4..774e9cd14302 100644
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c
@@ -2411,9 +2411,11 @@ static void efx_ef10_tx_init(struct efx_tx_queue *tx_queue)
 	/* TSOv2 is a limited resource that can only be configured on a limited
 	 * number of queues. TSO without checksum offload is not really a thing,
 	 * so we only enable it for those queues.
+	 * TSOv2 cannot be used with Hardware timestamping.
 	 */
 	if (csum_offload && (nic_data->datapath_caps2 &
-			(1 << MC_CMD_GET_CAPABILITIES_V2_OUT_TX_TSO_V2_LBN))) {
+			(1 << MC_CMD_GET_CAPABILITIES_V2_OUT_TX_TSO_V2_LBN)) &&
+	    !tx_queue->timestamping) {
 		tso_v2 = true;
 		netif_dbg(efx, hw, efx->net_dev, "Using TSOv2 for channel %u\n",
 				channel->channel);
@@ -2439,14 +2441,16 @@ static void efx_ef10_tx_init(struct efx_tx_queue *tx_queue)
 	inlen = MC_CMD_INIT_TXQ_IN_LEN(entries);
 
 	do {
-		MCDI_POPULATE_DWORD_3(inbuf, INIT_TXQ_IN_FLAGS,
+		MCDI_POPULATE_DWORD_4(inbuf, INIT_TXQ_IN_FLAGS,
 				/* This flag was removed from mcdi_pcol.h for
 				 * the non-_EXT version of INIT_TXQ.  However,
 				 * firmware still honours it.
 				 */
 				INIT_TXQ_EXT_IN_FLAG_TSOV2_EN, tso_v2,
 				INIT_TXQ_IN_FLAG_IP_CSUM_DIS, !csum_offload,
-				INIT_TXQ_IN_FLAG_TCP_CSUM_DIS, !csum_offload);
+				INIT_TXQ_IN_FLAG_TCP_CSUM_DIS, !csum_offload,
+				INIT_TXQ_EXT_IN_FLAG_TIMESTAMP,
+						tx_queue->timestamping);
 
 		rc = efx_mcdi_rpc_quiet(efx, MC_CMD_INIT_TXQ, inbuf, inlen,
 					NULL, 0, NULL);
@@ -2472,12 +2476,13 @@ static void efx_ef10_tx_init(struct efx_tx_queue *tx_queue)
 	tx_queue->buffer[0].flags = EFX_TX_BUF_OPTION;
 	tx_queue->insert_count = 1;
 	txd = efx_tx_desc(tx_queue, 0);
-	EFX_POPULATE_QWORD_4(*txd,
+	EFX_POPULATE_QWORD_5(*txd,
 			     ESF_DZ_TX_DESC_IS_OPT, true,
 			     ESF_DZ_TX_OPTION_TYPE,
 			     ESE_DZ_TX_OPTION_DESC_CRC_CSUM,
 			     ESF_DZ_TX_OPTION_UDP_TCP_CSUM, csum_offload,
-			     ESF_DZ_TX_OPTION_IP_CSUM, csum_offload);
+			     ESF_DZ_TX_OPTION_IP_CSUM, csum_offload,
+			     ESF_DZ_TX_TIMESTAMP, tx_queue->timestamping);
 	tx_queue->write_count = 1;
 
 	if (tso_v2) {
@@ -3572,6 +3577,17 @@ static int efx_ef10_handle_rx_event(struct efx_channel *channel,
 	return n_packets;
 }
 
+static u32 efx_ef10_extract_event_ts(efx_qword_t *event)
+{
+	u32 tstamp;
+
+	tstamp = EFX_QWORD_FIELD(*event, TX_TIMESTAMP_EVENT_TSTAMP_DATA_HI);
+	tstamp <<= 16;
+	tstamp |= EFX_QWORD_FIELD(*event, TX_TIMESTAMP_EVENT_TSTAMP_DATA_LO);
+
+	return tstamp;
+}
+
 static void
 efx_ef10_handle_tx_event(struct efx_channel *channel, efx_qword_t *event)
 {
@@ -3579,6 +3595,8 @@ efx_ef10_handle_tx_event(struct efx_channel *channel, efx_qword_t *event)
 	struct efx_tx_queue *tx_queue;
 	unsigned int tx_ev_desc_ptr;
 	unsigned int tx_ev_q_label;
+	unsigned int tx_ev_type;
+	u64 ts_part;
 
 	if (unlikely(READ_ONCE(efx->reset_pending)))
 		return;
@@ -3586,12 +3604,65 @@ efx_ef10_handle_tx_event(struct efx_channel *channel, efx_qword_t *event)
 	if (unlikely(EFX_QWORD_FIELD(*event, ESF_DZ_TX_DROP_EVENT)))
 		return;
 
-	/* Transmit completion */
-	tx_ev_desc_ptr = EFX_QWORD_FIELD(*event, ESF_DZ_TX_DESCR_INDX);
+	/* Get the transmit queue */
 	tx_ev_q_label = EFX_QWORD_FIELD(*event, ESF_DZ_TX_QLABEL);
 	tx_queue = efx_channel_get_tx_queue(channel,
 					    tx_ev_q_label % EFX_TXQ_TYPES);
-	efx_xmit_done(tx_queue, tx_ev_desc_ptr & tx_queue->ptr_mask);
+
+	if (!tx_queue->timestamping) {
+		/* Transmit completion */
+		tx_ev_desc_ptr = EFX_QWORD_FIELD(*event, ESF_DZ_TX_DESCR_INDX);
+		efx_xmit_done(tx_queue, tx_ev_desc_ptr & tx_queue->ptr_mask);
+		return;
+	}
+
+	/* Transmit timestamps are only available for 8XXX series. They result
+	 * in three events per packet. These occur in order, and are:
+	 *  - the normal completion event
+	 *  - the low part of the timestamp
+	 *  - the high part of the timestamp
+	 *
+	 * Each part of the timestamp is itself split across two 16 bit
+	 * fields in the event.
+	 */
+	tx_ev_type = EFX_QWORD_FIELD(*event, ESF_EZ_TX_SOFT1);
+
+	switch (tx_ev_type) {
+	case TX_TIMESTAMP_EVENT_TX_EV_COMPLETION:
+		/* In case of Queue flush or FLR, we might have received
+		 * the previous TX completion event but not the Timestamp
+		 * events.
+		 */
+		if (tx_queue->completed_desc_ptr != tx_queue->ptr_mask)
+			efx_xmit_done(tx_queue, tx_queue->completed_desc_ptr);
+
+		tx_ev_desc_ptr = EFX_QWORD_FIELD(*event,
+						 ESF_DZ_TX_DESCR_INDX);
+		tx_queue->completed_desc_ptr =
+					tx_ev_desc_ptr & tx_queue->ptr_mask;
+		break;
+
+	case TX_TIMESTAMP_EVENT_TX_EV_TSTAMP_LO:
+		ts_part = efx_ef10_extract_event_ts(event);
+		tx_queue->completed_timestamp_minor = ts_part;
+		break;
+
+	case TX_TIMESTAMP_EVENT_TX_EV_TSTAMP_HI:
+		ts_part = efx_ef10_extract_event_ts(event);
+		tx_queue->completed_timestamp_major = ts_part;
+
+		efx_xmit_done(tx_queue, tx_queue->completed_desc_ptr);
+		tx_queue->completed_desc_ptr = tx_queue->ptr_mask;
+		break;
+
+	default:
+		netif_err(efx, hw, efx->net_dev,
+			  "channel %d unknown tx event type %d (data "
+			  EFX_QWORD_FMT ")\n",
+			  channel->channel, tx_ev_type,
+			  EFX_QWORD_VAL(*event));
+		break;
+	}
 }
 
 static void