ethernet: ti: cpts: Use generic helper function

In order to reduce code duplication between ptp drivers, generic helper
functions were introduced. Use them.
Suggested-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/cpts.c

@@ -446,41 +446,22 @@ static const struct ptp_clock_info cpts_info = {
 static int cpts_skb_get_mtype_seqid(struct sk_buff *skb, u32 *mtype_seqid)
 {
 	unsigned int ptp_class = ptp_classify_raw(skb);
-	u8 *msgtype, *data = skb->data;
-	unsigned int offset = 0;
-	u16 *seqid;
+	struct ptp_header *hdr;
+	u8 msgtype;
+	u16 seqid;
 
 	if (ptp_class == PTP_CLASS_NONE)
 		return 0;
 
-	if (ptp_class & PTP_CLASS_VLAN)
-		offset += VLAN_HLEN;
-
-	switch (ptp_class & PTP_CLASS_PMASK) {
-	case PTP_CLASS_IPV4:
-		offset += ETH_HLEN + IPV4_HLEN(data + offset) + UDP_HLEN;
-		break;
-	case PTP_CLASS_IPV6:
-		offset += ETH_HLEN + IP6_HLEN + UDP_HLEN;
-		break;
-	case PTP_CLASS_L2:
-		offset += ETH_HLEN;
-		break;
-	default:
-		return 0;
-	}
-
-	if (skb->len + ETH_HLEN < offset + OFF_PTP_SEQUENCE_ID + sizeof(*seqid))
+	hdr = ptp_parse_header(skb, ptp_class);
+	if (!hdr)
 		return 0;
 
-	if (unlikely(ptp_class & PTP_CLASS_V1))
-		msgtype = data + offset + OFF_PTP_CONTROL;
-	else
-		msgtype = data + offset;
+	msgtype = ptp_get_msgtype(hdr, ptp_class);
+	seqid	= ntohs(hdr->sequence_id);
 
-	seqid = (u16 *)(data + offset + OFF_PTP_SEQUENCE_ID);
-	*mtype_seqid = (*msgtype & MESSAGE_TYPE_MASK) << MESSAGE_TYPE_SHIFT;
-	*mtype_seqid |= (ntohs(*seqid) & SEQUENCE_ID_MASK) << SEQUENCE_ID_SHIFT;
+	*mtype_seqid  = (msgtype & MESSAGE_TYPE_MASK) << MESSAGE_TYPE_SHIFT;
+	*mtype_seqid |= (seqid & SEQUENCE_ID_MASK) << SEQUENCE_ID_SHIFT;
 
 	return 1;
 }
@@ -528,6 +509,11 @@ void cpts_rx_timestamp(struct cpts *cpts, struct sk_buff *skb)
 	int ret;
 	u64 ns;
 
+	/* cpts_rx_timestamp() is called before eth_type_trans(), so
+	 * skb MAC Hdr properties are not configured yet. Hence need to
+	 * reset skb MAC header here
+	 */
+	skb_reset_mac_header(skb);
 	ret = cpts_skb_get_mtype_seqid(skb, &skb_cb->skb_mtype_seqid);
 	if (!ret)
 		return;