net: phy: BCM54210PE does not support PTP

BCM54213PE is an Ethernet PHY that supports PTP hardware timestamping.
BCM54210PW ia another Ethernet PHY, but one without PTP support.
Unfortunately the two PHYs return the same ID when queried, so some
extra information is required to determine whether the PHY is PTP-
capable.

There are two Raspberry Pi products that use these PHYs - Pi 4B and
CM4 - and fortunately they use different PHY addresses, so use that as
a differentiator. Choose to treat a PHY with the same ID but another
address as a BCM54210PE, which seems more common.

See: https://github.com/raspberrypi/linux/issues/5104

Signed-off-by: Phil Elwell <phil@raspberrypi.com>

drivers/net/phy/bcm-phy-ptp.c

@@ -912,6 +912,18 @@ struct bcm_ptp_private *bcm_ptp_probe(struct phy_device *phydev)
 	switch (BRCM_PHY_MODEL(phydev)) {
 	case PHY_ID_BCM54210E:
 		break;
+#ifdef PHY_ID_BCM54213PE
+	case PHY_ID_BCM54213PE:
+		switch (phydev->mdio.addr) {
+		case 0: // CM4 - this is a BCM54210PE which supports PTP
+			break;
+		case 1: //  4B - this is a BCM54213PE which doesn't
+			return NULL;
+		default: // Unknown - assume it's BCM54210PE
+			break;
+		}
+		break;
+#endif
 	default:
 		return NULL;
 	}