bnxt_en: Increase the max total outstanding PTP TX packets to 4

Start accepting up to 4 TX TS requests on BCM5750X (P5) chips.
These PTP TX packets will be queued in the ptp->txts_req[] array
waiting for the TX timestamp to complete.  The entries in the
array will be managed by a producer and consumer index.  The
producer index is updated under spinlock since multiple TX rings
can try to send PTP packets at the same time.

Signed-off-by: Pavan Chebbi <[email protected]>
Signed-off-by: Michael Chan <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Pavan Chebbi

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -457,8 +457,8 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	unsigned int length, pad = 0;
 	u32 len, free_size, vlan_tag_flags, cfa_action, flags;
 	struct bnxt_ptp_cfg *ptp = bp->ptp_cfg;
-	u16 prod, last_frag;
 	struct pci_dev *pdev = bp->pdev;
+	u16 prod, last_frag, txts_prod;
 	struct bnxt_tx_ring_info *txr;
 	struct bnxt_sw_tx_bd *tx_buf;
 	__le32 lflags = 0;
@@ -527,11 +527,19 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
 			if (!bnxt_ptp_parse(skb, &seq_id, &hdr_off)) {
 				if (vlan_tag_flags)
 					hdr_off += VLAN_HLEN;
-				ptp->txts_req.tx_seqid = seq_id;
-				ptp->txts_req.tx_hdr_off = hdr_off;
 				lflags |= cpu_to_le32(TX_BD_FLAGS_STAMP);
 				tx_buf->is_ts_pkt = 1;
 				skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
+
+				spin_lock_bh(&ptp->ptp_tx_lock);
+				txts_prod = ptp->txts_prod;
+				ptp->txts_prod = NEXT_TXTS(txts_prod);
+				spin_unlock_bh(&ptp->ptp_tx_lock);
+
+				ptp->txts_req[txts_prod].tx_seqid = seq_id;
+				ptp->txts_req[txts_prod].tx_hdr_off = hdr_off;
+				tx_buf->txts_prod = txts_prod;
+
 			} else {
 				atomic_inc(&bp->ptp_cfg->tx_avail);
 			}
@@ -769,7 +777,9 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (BNXT_TX_PTP_IS_SET(lflags)) {
 		txr->tx_buf_ring[txr->tx_prod].is_ts_pkt = 0;
 		atomic64_inc(&bp->ptp_cfg->stats.ts_err);
-		atomic_inc(&bp->ptp_cfg->tx_avail);
+		if (!(bp->fw_cap & BNXT_FW_CAP_TX_TS_CMP))
+			/* set SKB to err so PTP worker will clean up */
+			ptp->txts_req[txts_prod].tx_skb = ERR_PTR(-EIO);
 	}
 	if (txr->kick_pending)
 		bnxt_txr_db_kick(bp, txr, txr->tx_prod);
@@ -837,7 +847,7 @@ static bool __bnxt_tx_int(struct bnxt *bp, struct bnxt_tx_ring_info *txr,
 		if (unlikely(is_ts_pkt)) {
 			if (BNXT_CHIP_P5(bp)) {
 				/* PTP worker takes ownership of the skb */
-				bnxt_get_tx_ts_p5(bp, skb);
+				bnxt_get_tx_ts_p5(bp, skb, tx_buf->txts_prod);
 				skb = NULL;
 			}
 		}

drivers/net/ethernet/broadcom/bnxt/bnxt.h

@@ -878,7 +878,10 @@ struct bnxt_sw_tx_bd {
 	u8			is_push;
 	u8			action;
 	unsigned short		nr_frags;
-	u16			rx_prod;
+	union {
+		u16			rx_prod;
+		u16			txts_prod;
+	};
 };
 
 struct bnxt_sw_rx_bd {

drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c

@@ -110,7 +110,7 @@ static void bnxt_ptp_get_current_time(struct bnxt *bp)
 }
 
 static int bnxt_hwrm_port_ts_query(struct bnxt *bp, u32 flags, u64 *ts,
-				   u32 txts_tmo)
+				   u32 txts_tmo, int slot)
 {
 	struct hwrm_port_ts_query_output *resp;
 	struct hwrm_port_ts_query_input *req;
@@ -123,7 +123,7 @@ static int bnxt_hwrm_port_ts_query(struct bnxt *bp, u32 flags, u64 *ts,
 	req->flags = cpu_to_le32(flags);
 	if ((flags & PORT_TS_QUERY_REQ_FLAGS_PATH) ==
 	    PORT_TS_QUERY_REQ_FLAGS_PATH_TX) {
-		struct bnxt_ptp_tx_req *txts_req = &bp->ptp_cfg->txts_req;
+		struct bnxt_ptp_tx_req *txts_req = &bp->ptp_cfg->txts_req[slot];
 		u32 tmo_us = txts_tmo * 1000;
 
 		req->enables = cpu_to_le16(BNXT_PTP_QTS_TX_ENABLES);
@@ -683,7 +683,7 @@ static u64 bnxt_cc_read(const struct cyclecounter *cc)
 	return ns;
 }
 
-static int bnxt_stamp_tx_skb(struct bnxt *bp, struct sk_buff *skb)
+static int bnxt_stamp_tx_skb(struct bnxt *bp, int slot)
 {
 	struct bnxt_ptp_cfg *ptp = bp->ptp_cfg;
 	struct skb_shared_hwtstamps timestamp;
@@ -693,13 +693,13 @@ static int bnxt_stamp_tx_skb(struct bnxt *bp, struct sk_buff *skb)
 	u32 tmo = 0;
 	int rc;
 
-	txts_req = &ptp->txts_req;
-	if (!txts_req->txts_pending)
-		txts_req->abs_txts_tmo = now + msecs_to_jiffies(ptp->txts_tmo);
+	txts_req = &ptp->txts_req[slot];
+	/* make sure bnxt_get_tx_ts_p5() has updated abs_txts_tmo */
+	smp_rmb();
 	if (!time_after_eq(now, txts_req->abs_txts_tmo))
 		tmo = jiffies_to_msecs(txts_req->abs_txts_tmo - now);
 	rc = bnxt_hwrm_port_ts_query(bp, PORT_TS_QUERY_REQ_FLAGS_PATH_TX, &ts,
-				     tmo);
+				     tmo, slot);
 	if (!rc) {
 		memset(&timestamp, 0, sizeof(timestamp));
 		spin_lock_bh(&ptp->ptp_lock);
@@ -709,19 +709,16 @@ static int bnxt_stamp_tx_skb(struct bnxt *bp, struct sk_buff *skb)
 		skb_tstamp_tx(txts_req->tx_skb, &timestamp);
 		ptp->stats.ts_pkts++;
 	} else {
-		if (!time_after_eq(jiffies, txts_req->abs_txts_tmo)) {
-			txts_req->txts_pending = true;
+		if (!time_after_eq(jiffies, txts_req->abs_txts_tmo))
 			return -EAGAIN;
-		}
+
 		ptp->stats.ts_lost++;
 		netdev_warn_once(bp->dev,
 				 "TS query for TX timer failed rc = %x\n", rc);
 	}
 
 	dev_kfree_skb_any(txts_req->tx_skb);
 	txts_req->tx_skb = NULL;
-	atomic_inc(&ptp->tx_avail);
-	txts_req->txts_pending = false;
 
 	return 0;
 }
@@ -732,10 +729,24 @@ static long bnxt_ptp_ts_aux_work(struct ptp_clock_info *ptp_info)
 						ptp_info);
 	unsigned long now = jiffies;
 	struct bnxt *bp = ptp->bp;
+	u16 cons = ptp->txts_cons;
+	u8 num_requests;
 	int rc = 0;
 
-	if (ptp->txts_req.tx_skb)
-		rc = bnxt_stamp_tx_skb(bp, ptp->txts_req.tx_skb);
+	num_requests = BNXT_MAX_TX_TS - atomic_read(&ptp->tx_avail);
+	while (num_requests--) {
+		if (IS_ERR(ptp->txts_req[cons].tx_skb))
+			goto next_slot;
+		if (!ptp->txts_req[cons].tx_skb)
+			break;
+		rc = bnxt_stamp_tx_skb(bp, cons);
+		if (rc == -EAGAIN)
+			break;
+next_slot:
+		atomic_inc(&ptp->tx_avail);
+		cons = NEXT_TXTS(cons);
+	}
+	ptp->txts_cons = cons;
 
 	if (!time_after_eq(now, ptp->next_period)) {
 		if (rc == -EAGAIN)
@@ -756,11 +767,16 @@ static long bnxt_ptp_ts_aux_work(struct ptp_clock_info *ptp_info)
 	return HZ;
 }
 
-void bnxt_get_tx_ts_p5(struct bnxt *bp, struct sk_buff *skb)
+void bnxt_get_tx_ts_p5(struct bnxt *bp, struct sk_buff *skb, u16 prod)
 {
 	struct bnxt_ptp_cfg *ptp = bp->ptp_cfg;
+	struct bnxt_ptp_tx_req *txts_req;
 
-	ptp->txts_req.tx_skb = skb;
+	txts_req = &ptp->txts_req[prod];
+	txts_req->abs_txts_tmo = jiffies + msecs_to_jiffies(ptp->txts_tmo);
+	/* make sure abs_txts_tmo is written first */
+	smp_wmb();
+	txts_req->tx_skb = skb;
 	ptp_schedule_worker(ptp->ptp_clock, 0);
 }
 
@@ -958,7 +974,7 @@ int bnxt_ptp_init_rtc(struct bnxt *bp, bool phc_cfg)
 			return rc;
 	} else {
 		rc = bnxt_hwrm_port_ts_query(bp, PORT_TS_QUERY_REQ_FLAGS_CURRENT_TIME,
-					     &ns, 0);
+					     &ns, 0, 0);
 		if (rc)
 			return rc;
 	}
@@ -1000,6 +1016,7 @@ int bnxt_ptp_init(struct bnxt *bp, bool phc_cfg)
 
 	atomic_set(&ptp->tx_avail, BNXT_MAX_TX_TS);
 	spin_lock_init(&ptp->ptp_lock);
+	spin_lock_init(&ptp->ptp_tx_lock);
 
 	if (BNXT_PTP_USE_RTC(bp)) {
 		bnxt_ptp_timecounter_init(bp, false);
@@ -1049,6 +1066,7 @@ int bnxt_ptp_init(struct bnxt *bp, bool phc_cfg)
 void bnxt_ptp_clear(struct bnxt *bp)
 {
 	struct bnxt_ptp_cfg *ptp = bp->ptp_cfg;
+	int i;
 
 	if (!ptp)
 		return;
@@ -1060,9 +1078,11 @@ void bnxt_ptp_clear(struct bnxt *bp)
 	kfree(ptp->ptp_info.pin_config);
 	ptp->ptp_info.pin_config = NULL;
 
-	if (ptp->txts_req.tx_skb) {
-		dev_kfree_skb_any(ptp->txts_req.tx_skb);
-		ptp->txts_req.tx_skb = NULL;
+	for (i = 0; i < BNXT_MAX_TX_TS; i++) {
+		if (ptp->txts_req[i].tx_skb) {
+			dev_kfree_skb_any(ptp->txts_req[i].tx_skb);
+			ptp->txts_req[i].tx_skb = NULL;
+		}
 	}
 
 	bnxt_unmap_ptp_regs(bp);

drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.h

@@ -85,11 +85,13 @@ struct bnxt_ptp_stats {
 	atomic64_t	ts_err;
 };
 
+#define BNXT_MAX_TX_TS		4
+#define NEXT_TXTS(idx)		(((idx) + 1) & (BNXT_MAX_TX_TS - 1))
+
 struct bnxt_ptp_tx_req {
 	struct sk_buff		*tx_skb;
 	u16			tx_seqid;
 	u16			tx_hdr_off;
-	u8			txts_pending:1;
 	unsigned long		abs_txts_tmo;
 };
 
@@ -101,6 +103,8 @@ struct bnxt_ptp_cfg {
 	struct bnxt_pps		pps_info;
 	/* serialize timecounter access */
 	spinlock_t		ptp_lock;
+	/* serialize ts tx request queuing */
+	spinlock_t		ptp_tx_lock;
 	u64			current_time;
 	u64			old_time;
 	unsigned long		next_period;
@@ -109,11 +113,10 @@ struct bnxt_ptp_cfg {
 	/* a 23b shift cyclecounter will overflow in ~36 mins.  Check overflow every 18 mins. */
 	#define BNXT_PHC_OVERFLOW_PERIOD	(18 * 60 * HZ)
 
-	struct bnxt_ptp_tx_req	txts_req;
+	struct bnxt_ptp_tx_req	txts_req[BNXT_MAX_TX_TS];
 
 	struct bnxt		*bp;
 	atomic_t		tx_avail;
-#define BNXT_MAX_TX_TS	1
 	u16			rxctl;
 #define BNXT_PTP_MSG_SYNC			(1 << 0)
 #define BNXT_PTP_MSG_DELAY_REQ			(1 << 1)
@@ -136,6 +139,8 @@ struct bnxt_ptp_cfg {
 	u32			refclk_regs[2];
 	u32			refclk_mapped_regs[2];
 	u32			txts_tmo;
+	u16			txts_prod;
+	u16			txts_cons;
 
 	struct bnxt_ptp_stats	stats;
 };
@@ -159,7 +164,7 @@ int bnxt_ptp_cfg_tstamp_filters(struct bnxt *bp);
 void bnxt_ptp_reapply_pps(struct bnxt *bp);
 int bnxt_hwtstamp_set(struct net_device *dev, struct ifreq *ifr);
 int bnxt_hwtstamp_get(struct net_device *dev, struct ifreq *ifr);
-void bnxt_get_tx_ts_p5(struct bnxt *bp, struct sk_buff *skb);
+void bnxt_get_tx_ts_p5(struct bnxt *bp, struct sk_buff *skb, u16 prod);
 int bnxt_get_rx_ts_p5(struct bnxt *bp, u64 *ts, u32 pkt_ts);
 void bnxt_tx_ts_cmp(struct bnxt *bp, struct bnxt_napi *bnapi,
 		    struct tx_ts_cmp *tscmp);