pps/ptp: Allow PHC devices to adjust PPS events for known delay

Initial version by Stuart Hodgson <smhodgson@solarflare.com>

Some PHC device drivers may deliver PPS events with a significant
and variable delay, but still be able to measure precisely what
that delay is.

Add a pps_sub_ts() function for subtracting a delay from the
timestamp(s) in a PPS event, and a PTP event type (PTP_CLOCK_PPSUSR)
for which the caller provides a complete PPS event.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
index 1e528b539a07..966875dcda56 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -300,6 +300,11 @@ void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
                 pps_get_ts(&evt);
                 pps_event(ptp->pps_source, &evt, PTP_PPS_EVENT, NULL);
                 break;
+
+        case PTP_CLOCK_PPSUSR:
+                pps_event(ptp->pps_source, &event->pps_times,
+                          PTP_PPS_EVENT, NULL);
+                break;
         }
 }
 EXPORT_SYMBOL(ptp_clock_event);