bnxt_en: Fix HWTSTAMP_FILTER_ALL packet timestamp logic

When the chip is configured to timestamp all receive packets, the
timestamp in the RX completion is only valid if the metadata
present flag is not set for packets received on the wire.  In
addition, internal loopback packets will never have a valid timestamp
and the timestamp field will always be zero.  We must exclude
any 0 value in the timestamp field because there is no way to
determine if it is a loopback packet or not.

Add a new function bnxt_rx_ts_valid() to check for all timestamp
valid conditions.

Fixes: 66ed81dc ("bnxt_en: Enable packet timestamping for all RX packets")
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Link: https://lore.kernel.org/r/20231208001658.14230-5-michael.chan@broadcom.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -1759,6 +1759,21 @@ static void bnxt_deliver_skb(struct bnxt *bp, struct bnxt_napi *bnapi,
 	napi_gro_receive(&bnapi->napi, skb);
 }
 
+static bool bnxt_rx_ts_valid(struct bnxt *bp, u32 flags,
+			     struct rx_cmp_ext *rxcmp1, u32 *cmpl_ts)
+{
+	u32 ts = le32_to_cpu(rxcmp1->rx_cmp_timestamp);
+
+	if (BNXT_PTP_RX_TS_VALID(flags))
+		goto ts_valid;
+	if (!bp->ptp_all_rx_tstamp || !ts || !BNXT_ALL_RX_TS_VALID(flags))
+		return false;
+
+ts_valid:
+	*cmpl_ts = ts;
+	return true;
+}
+
 /* returns the following:
  * 1       - 1 packet successfully received
  * 0       - successful TPA_START, packet not completed yet
@@ -1784,6 +1799,7 @@ static int bnxt_rx_pkt(struct bnxt *bp, struct bnxt_cp_ring_info *cpr,
 	struct sk_buff *skb;
 	struct xdp_buff xdp;
 	u32 flags, misc;
+	u32 cmpl_ts;
 	void *data;
 	int rc = 0;
 
@@ -2006,10 +2022,8 @@ static int bnxt_rx_pkt(struct bnxt *bp, struct bnxt_cp_ring_info *cpr,
 		}
 	}
 
-	if (unlikely((flags & RX_CMP_FLAGS_ITYPES_MASK) ==
-		     RX_CMP_FLAGS_ITYPE_PTP_W_TS) || bp->ptp_all_rx_tstamp) {
+	if (bnxt_rx_ts_valid(bp, flags, rxcmp1, &cmpl_ts)) {
 		if (bp->flags & BNXT_FLAG_CHIP_P5) {
-			u32 cmpl_ts = le32_to_cpu(rxcmp1->rx_cmp_timestamp);
 			u64 ns, ts;
 
 			if (!bnxt_get_rx_ts_p5(bp, &ts, cmpl_ts)) {

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

@@ -161,7 +161,7 @@ struct rx_cmp {
 	#define RX_CMP_FLAGS_ERROR				(1 << 6)
 	#define RX_CMP_FLAGS_PLACEMENT				(7 << 7)
 	#define RX_CMP_FLAGS_RSS_VALID				(1 << 10)
-	#define RX_CMP_FLAGS_UNUSED				(1 << 11)
+	#define RX_CMP_FLAGS_PKT_METADATA_PRESENT		(1 << 11)
 	 #define RX_CMP_FLAGS_ITYPES_SHIFT			 12
 	 #define RX_CMP_FLAGS_ITYPES_MASK			 0xf000
 	 #define RX_CMP_FLAGS_ITYPE_UNKNOWN			 (0 << 12)
@@ -188,6 +188,12 @@ struct rx_cmp {
 	__le32 rx_cmp_rss_hash;
 };
 
+#define BNXT_PTP_RX_TS_VALID(flags)				\
+	(((flags) & RX_CMP_FLAGS_ITYPES_MASK) == RX_CMP_FLAGS_ITYPE_PTP_W_TS)
+
+#define BNXT_ALL_RX_TS_VALID(flags)				\
+	!((flags) & RX_CMP_FLAGS_PKT_METADATA_PRESENT)
+
 #define RX_CMP_HASH_VALID(rxcmp)				\
 	((rxcmp)->rx_cmp_len_flags_type & cpu_to_le32(RX_CMP_FLAGS_RSS_VALID))