mlxsw: spectrum_ptp: Use generic helper function

In order to reduce code duplication between ptp drivers, generic helper
functions were introduced. Use them.
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-and-tested-by: Petr Machata <petrm@mellanox.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c

@@ -314,11 +314,9 @@ static int mlxsw_sp_ptp_parse(struct sk_buff *skb,
 			      u8 *p_message_type,
 			      u16 *p_sequence_id)
 {
-	unsigned int offset = 0;
 	unsigned int ptp_class;
-	u8 *data;
+	struct ptp_header *hdr;
 
-	data = skb_mac_header(skb);
 	ptp_class = ptp_classify_raw(skb);
 
 	switch (ptp_class & PTP_CLASS_VMASK) {
@@ -329,30 +327,14 @@ static int mlxsw_sp_ptp_parse(struct sk_buff *skb,
 		return -ERANGE;
 	}
 
-	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 -ERANGE;
-	}
-
-	/* PTP header is 34 bytes. */
-	if (skb->len < offset + 34)
+	hdr = ptp_parse_header(skb, ptp_class);
+	if (!hdr)
 		return -EINVAL;
 
-	*p_message_type = data[offset] & 0x0f;
-	*p_domain_number = data[offset + 4];
-	*p_sequence_id = (u16)(data[offset + 30]) << 8 | data[offset + 31];
+	*p_message_type	 = ptp_get_msgtype(hdr, ptp_class);
+	*p_domain_number = hdr->domain_number;
+	*p_sequence_id	 = be16_to_cpu(hdr->sequence_id);
+
 	return 0;
 }