ts2phc: Don't switch system clock to nanosecond mode.

ts2phc is not synchronizing the system clock and should not switch the
clock to the nanosecond mode with adjtimex(modes=ADJ_NANO) or make any
other modifications to it. The process that is controlling the clock
(e.g. an NTP client) might not be using the nanosecond mode.

There are two instances of the adjtimex() call in the code. One is used
only to read the clock and can be replaced with faster clock_gettime().
The other instance is also reading the TAI offset. Instead of switching
to the nanosecond mode, change the timestamp conversion to handle both
microsecond and nanosecond modes according to the current clock status.

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>

ts2phc_generic_pps_source.c

@@ -38,7 +38,6 @@ static int get_ntx(struct timex *ntx)
 		return -1;
 
 	memset(ntx, 0, sizeof(*ntx));
-	ntx->modes = ADJ_NANO;
 	code = adjtimex(ntx);
 	if (code == -1) {
 		pr_err("adjtimex failed: %m");
@@ -93,7 +92,10 @@ static int ts2phc_generic_pps_source_getppstime(struct ts2phc_pps_source *src,
 	}
 
 	ts->tv_sec  = ntx.time.tv_sec + tai_offset;
-	ts->tv_nsec = ntx.time.tv_usec;
+	if (ntx.status & STA_NANO)
+		ts->tv_nsec = ntx.time.tv_usec;
+	else
+		ts->tv_nsec = ntx.time.tv_usec * 1000;
 
 	return 0;
 }

ts2phc_nmea_pps_source.c

@@ -62,14 +62,13 @@ static int open_nmea_connection(const char *host, const char *port,
 
 static void *monitor_nmea_status(void *arg)
 {
+	struct timespec rxtime, rxtime_rt, tmo = { 2, 0 };
 	struct nmea_parser *np = nmea_parser_create();
 	struct pollfd pfd = { -1, POLLIN | POLLPRI };
 	char *host, input[256], *port, *ptr, *uart;
 	struct ts2phc_nmea_pps_source *s = arg;
-	struct timespec rxtime, tmo = { 2, 0 };
 	int cnt, num, parsed, baud;
 	struct nmea_rmc rmc;
-	struct timex ntx;
 
 	if (!np) {
 		pr_err("failed to create NMEA parser");
@@ -79,8 +78,6 @@ static void *monitor_nmea_status(void *arg)
 	port = config_get_string(s->config, NULL, "ts2phc.nmea_remote_port");
 	uart = config_get_string(s->config, NULL, "ts2phc.nmea_serialport");
 	baud = config_get_int(s->config, NULL, "ts2phc.nmea_baudrate");
-	memset(&ntx, 0, sizeof(ntx));
-	ntx.modes = ADJ_NANO;
 
 	while (is_running()) {
 		if (pfd.fd == -1) {
@@ -92,7 +89,7 @@ static void *monitor_nmea_status(void *arg)
 		}
 		num = poll(&pfd, 1, NMEA_TMO);
 		clock_gettime(CLOCK_MONOTONIC, &rxtime);
-		adjtimex(&ntx);
+		clock_gettime(CLOCK_REALTIME, &rxtime_rt);
 		if (num < 0) {
 			pr_err("poll failed");
 			break;
@@ -124,8 +121,7 @@ static void *monitor_nmea_status(void *arg)
 			if (!nmea_parse(np, ptr, cnt, &rmc, &parsed)) {
 				pthread_mutex_lock(&s->mutex);
 				s->local_monotime = rxtime;
-				s->local_utctime.tv_sec = ntx.time.tv_sec;
-				s->local_utctime.tv_nsec = ntx.time.tv_usec;
+				s->local_utctime = rxtime_rt;
 				s->rmc_utctime = rmc.ts;
 				s->rmc_fix_valid = rmc.fix_valid;
 				pthread_mutex_unlock(&s->mutex);