net: mscc: allow offloading timestamping operations to the PHY

This patch adds support for offloading timestamping operations not only
to the Ocelot switch (as already supported) but to compatible PHYs.
When both the PHY and the Ocelot switch support timestamping operations,
the PHY implementation is chosen as the timestamp will happen closer to
the medium.
Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mscc/ocelot.c

@@ -1204,7 +1204,10 @@ static int ocelot_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 	struct ocelot *ocelot = priv->port.ocelot;
 	int port = priv->chip_port;
 
-	if (ocelot->ptp) {
+	/* If the attached PHY device isn't capable of timestamping operations,
+	 * use our own (when possible).
+	 */
+	if (!phy_has_hwtstamp(dev->phydev) && ocelot->ptp) {
 		switch (cmd) {
 		case SIOCSHWTSTAMP:
 			return ocelot_hwstamp_set(ocelot, port, ifr);

drivers/net/ethernet/mscc/ocelot_board.c

@@ -189,7 +189,8 @@ static irqreturn_t ocelot_xtr_irq_handler(int irq, void *arg)
 			skb->offload_fwd_mark = 1;
 
 		skb->protocol = eth_type_trans(skb, dev);
-		netif_rx(skb);
+		if (!skb_defer_rx_timestamp(skb))
+			netif_rx(skb);
 		dev->stats.rx_bytes += len;
 		dev->stats.rx_packets++;
 	} while (ocelot_read(ocelot, QS_XTR_DATA_PRESENT) & BIT(grp));