ptp_clock: Let the ADJ_OFFSET interface respect the ADJ_NANO flag for PHC devices.

In commit 184ecc9e ("ptp: Add adjphase
function to support phase offset control.") the PTP Hardware Clock
interface expanded to support the ADJ_OFFSET offset mode.  However,
the implementation did not respect the traditional yet pedantic
distinction between units of microseconds and nanoseconds signaled by
the ADJ_NANO flag.  This patch fixes the issue by adding logic to
handle that flag.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Reviewed-by: Vincent Cheng <vincent.cheng.xh@renesas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/ptp/ptp_clock.c

@@ -147,8 +147,14 @@ static int ptp_clock_adjtime(struct posix_clock *pc, struct __kernel_timex *tx)
 			err = ops->adjfreq(ops, ppb);
 		ptp->dialed_frequency = tx->freq;
 	} else if (tx->modes & ADJ_OFFSET) {
-		if (ops->adjphase)
-			err = ops->adjphase(ops, tx->offset);
+		if (ops->adjphase) {
+			s32 offset = tx->offset;
+
+			if (!(tx->modes & ADJ_NANO))
+				offset *= NSEC_PER_USEC;
+
+			err = ops->adjphase(ops, offset);
+		}
 	} else if (tx->modes == 0) {
 		tx->freq = ptp->dialed_frequency;
 		err = 0;