igb: Reject requests that fail to enable time stamping on both edges.

This hardware always time stamps rising and falling edges, and so this
patch validates that the request does contains both edges.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/igb/igb_ptp.c

@@ -528,6 +528,12 @@ static int igb_ptp_feature_enable_i210(struct ptp_clock_info *ptp,
 					PTP_STRICT_FLAGS))
 			return -EOPNOTSUPP;
 
+		/* Reject requests failing to enable both edges. */
+		if ((rq->extts.flags & PTP_STRICT_FLAGS) &&
+		    (rq->extts.flags & PTP_ENABLE_FEATURE) &&
+		    (rq->extts.flags & PTP_EXTTS_EDGES) != PTP_EXTTS_EDGES)
+			return -EOPNOTSUPP;
+
 		if (on) {
 			pin = ptp_find_pin(igb->ptp_clock, PTP_PF_EXTTS,
 					   rq->extts.index);