dp83640: Verify calibration pin assignment

This constraints the pin assignment to not allow the calibration function to
be reassigned and only allow reassigning the calibratin pin if only one phy is
connected.

Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/dp83640.c

@@ -510,6 +510,16 @@ static int ptp_dp83640_enable(struct ptp_clock_info *ptp,
 static int ptp_dp83640_verify(struct ptp_clock_info *ptp, unsigned int pin,
 			      enum ptp_pin_function func, unsigned int chan)
 {
+	struct dp83640_clock *clock =
+		container_of(ptp, struct dp83640_clock, caps);
+
+	if (clock->caps.pin_config[pin].func == PTP_PF_PHYSYNC &&
+	    !list_empty(&clock->phylist))
+		return 1;
+
+	if (func == PTP_PF_PHYSYNC)
+		return 1;
+
 	return 0;
 }