net/bnxt: fix Rx timestamp when FIFO pending bit is set

[ upstream commit f8120fd ]

Fix to clear the Rx FIFO while reading the timestamp.
If the Rx FIFO has pending bit set, keep reading to clear it
and return the last valid timestamp instead of unconditionally
returning an error.

Fixes: b11cceb ("net/bnxt: support timesync")

Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>

drivers/net/bnxt/bnxt.h

@@ -316,6 +316,7 @@ struct rte_flow {
 	struct bnxt_vnic_info	*vnic;
 };
 
+#define BNXT_PTP_RX_PND_CNT		10
 #define BNXT_PTP_FLAGS_PATH_TX		0x0
 #define BNXT_PTP_FLAGS_PATH_RX		0x1
 #define BNXT_PTP_FLAGS_CURRENT_TIME	0x2

drivers/net/bnxt/bnxt_ethdev.c

@@ -3373,6 +3373,38 @@ static int bnxt_get_tx_ts(struct bnxt *bp, uint64_t *ts)
 	return 0;
 }
 
+static int bnxt_clr_rx_ts(struct bnxt *bp, uint64_t *last_ts)
+{
+	struct bnxt_ptp_cfg *ptp = bp->ptp_cfg;
+	struct bnxt_pf_info *pf = bp->pf;
+	uint16_t port_id;
+	int i = 0;
+	uint32_t fifo;
+
+	if (!ptp || (bp->flags & BNXT_FLAG_THOR_CHIP))
+		return -EINVAL;
+
+	port_id = pf->port_id;
+	fifo = rte_le_to_cpu_32(rte_read32((uint8_t *)bp->bar0 +
+				ptp->rx_mapped_regs[BNXT_PTP_RX_FIFO]));
+	while ((fifo & BNXT_PTP_RX_FIFO_PENDING) && (i < BNXT_PTP_RX_PND_CNT)) {
+		rte_write32(1 << port_id, (uint8_t *)bp->bar0 +
+			    ptp->rx_mapped_regs[BNXT_PTP_RX_FIFO_ADV]);
+		fifo = rte_le_to_cpu_32(rte_read32((uint8_t *)bp->bar0 +
+					ptp->rx_mapped_regs[BNXT_PTP_RX_FIFO]));
+		*last_ts = rte_le_to_cpu_32(rte_read32((uint8_t *)bp->bar0 +
+					ptp->rx_mapped_regs[BNXT_PTP_RX_TS_L]));
+		*last_ts |= (uint64_t)rte_le_to_cpu_32(rte_read32((uint8_t *)bp->bar0 +
+					ptp->rx_mapped_regs[BNXT_PTP_RX_TS_H])) << 32;
+		i++;
+	}
+
+	if (i >= BNXT_PTP_RX_PND_CNT)
+		return -EBUSY;
+
+	return 0;
+}
+
 static int bnxt_get_rx_ts(struct bnxt *bp, uint64_t *ts)
 {
 	struct bnxt_ptp_cfg *ptp = bp->ptp_cfg;
@@ -3391,10 +3423,8 @@ static int bnxt_get_rx_ts(struct bnxt *bp, uint64_t *ts)
 
 	fifo = rte_le_to_cpu_32(rte_read32((uint8_t *)bp->bar0 +
 				   ptp->rx_mapped_regs[BNXT_PTP_RX_FIFO]));
-	if (fifo & BNXT_PTP_RX_FIFO_PENDING) {
-/*		bnxt_clr_rx_ts(bp);	  TBD  */
-		return -EBUSY;
-	}
+	if (fifo & BNXT_PTP_RX_FIFO_PENDING)
+		return bnxt_clr_rx_ts(bp, ts);
 
 	*ts = rte_le_to_cpu_32(rte_read32((uint8_t *)bp->bar0 +
 				ptp->rx_mapped_regs[BNXT_PTP_RX_TS_L]));