ts2phc: allow the PHC PPS master to be synchronized

Now that we are registering a clock even for the PPS master when it
supports that (i.e. when it is a PHC), introduce a new API to retrieve
its clock in order to add timestamps to it.

The PHC master can be synchronized to the extts events of a PHC slave,
when in automatic mode.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>

ts2phc.c

@@ -477,6 +477,42 @@ static void ts2phc_synchronize_clocks(struct ts2phc_private *priv, int autocfg)
 	}
 }
 
+static int ts2phc_collect_master_tstamp(struct ts2phc_private *priv)
+{
+	struct clock *master_clock;
+	struct timespec master_ts;
+	int err;
+
+	master_clock = ts2phc_master_get_clock(priv->master);
+	/*
+	 * Master isn't a PHC (it may be a generic or a GPS master),
+	 * don't error out, just don't do anything. If it doesn't have a PHC,
+	 * there is nothing to synchronize, which is the only point of
+	 * collecting its perout timestamp in the first place.
+	 */
+	if (!master_clock)
+		return 0;
+
+	err = ts2phc_master_getppstime(priv->master, &master_ts);
+	if (err < 0) {
+		pr_err("source ts not valid");
+		return err;
+	}
+
+	/*
+	 * As long as the kernel doesn't support a proper API for reporting
+	 * a precise perout timestamp, we'll have to use this crude
+	 * approximation.
+	 */
+	if (master_ts.tv_nsec > NS_PER_SEC / 2)
+		master_ts.tv_sec++;
+	master_ts.tv_nsec = 0;
+
+	clock_add_tstamp(master_clock, timespec_to_tmv(master_ts));
+
+	return 0;
+}
+
 static void usage(char *progname)
 {
 	fprintf(stderr,
@@ -695,9 +731,16 @@ int main(int argc, char *argv[])
 			pr_err("poll failed");
 			break;
 		}
-		if (err > 0)
+		if (err > 0) {
+			err = ts2phc_collect_master_tstamp(&priv);
+			if (err) {
+				pr_err("failed to collect master tstamp");
+				break;
+			}
+
 			ts2phc_synchronize_clocks(&priv, autocfg);
 		}
+	}
 
 	ts2phc_cleanup(&priv);
 	return err;

ts2phc_master.c

@@ -38,3 +38,11 @@ int ts2phc_master_getppstime(struct ts2phc_master *master, struct timespec *ts)
 {
 	return master->getppstime(master, ts);
 }
+
+struct clock *ts2phc_master_get_clock(struct ts2phc_master *m)
+{
+	if (m->get_clock)
+		return m->get_clock(m);
+
+	return NULL;
+}

ts2phc_master.h

@@ -51,4 +51,6 @@ void ts2phc_master_destroy(struct ts2phc_master *master);
  */
 int ts2phc_master_getppstime(struct ts2phc_master *master, struct timespec *ts);
 
+struct clock *ts2phc_master_get_clock(struct ts2phc_master *m);
+
 #endif

ts2phc_master_private.h

@@ -15,6 +15,7 @@
 struct ts2phc_master {
 	void (*destroy)(struct ts2phc_master *ts2phc_master);
 	int (*getppstime)(struct ts2phc_master *master, struct timespec *ts);
+	struct clock *(*get_clock)(struct ts2phc_master *m);
 };
 
 #endif

ts2phc_phc_master.c

@@ -83,6 +83,14 @@ static int ts2phc_phc_master_getppstime(struct ts2phc_master *m,
 	return clock_gettime(master->clock->clkid, ts);
 }
 
+struct clock *ts2phc_phc_master_get_clock(struct ts2phc_master *m)
+{
+	struct ts2phc_phc_master *master =
+		container_of(m, struct ts2phc_phc_master, master);
+
+	return master->clock;
+}
+
 struct ts2phc_master *ts2phc_phc_master_create(struct ts2phc_private *priv,
 					       const char *dev)
 {
@@ -94,6 +102,7 @@ struct ts2phc_master *ts2phc_phc_master_create(struct ts2phc_private *priv,
 	}
 	master->master.destroy = ts2phc_phc_master_destroy;
 	master->master.getppstime = ts2phc_phc_master_getppstime;
+	master->master.get_clock = ts2phc_phc_master_get_clock;
 
 	master->clock = clock_add(priv, dev);
 	if (!master->clock) {