[PATCH 5.15 059/206] testptp: add option to shift clock by nanoseconds

Greg Kroah-Hartman
2026-02-04T14:56:35Z

From: Maciek Machnikowski <maciek@machnikowski.net>

[ Upstream commit f64ae40de5efaa33c36f4e2226b33824ba1b42a7 ]

Add option to shift the clock by a specified number of nanoseconds.

The new argument -n will specify the number of nanoseconds to add to the
ptp clock. Since the API doesn't support negative shifts those needs to
be calculated by subtracting full seconds and adding a nanosecond offset.

Signed-off-by: Maciek Machnikowski <maciek@machnikowski.net>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Link: https://lore.kernel.org/r/20220221200637.125595-1-maciek@machnikowski.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 76868642e427 ("testptp: Add option to open PHC in readonly mode")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/ptp/testptp.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/ptp/testptp.c b/tools/testing/selftests/ptp/testptp.c
index aa474febb4712..b943a594ea733 100644
--- a/tools/testing/selftests/ptp/testptp.c
+++ b/tools/testing/selftests/ptp/testptp.c
@@ -133,6 +133,7 @@ static void usage(char *progname)
" 0 - none\n"
" 1 - external time stamp\n"
" 2 - periodic output\n"
+ " -n val shift the ptp clock time by 'val' nanoseconds\n"
" -p val enable output with a period of 'val' nanoseconds\n"
" -H val set output phase to 'val' nanoseconds (requires -p)\n"
" -w val set output pulse width to 'val' nanoseconds (requires -p)\n"
@@ -165,6 +166,7 @@ int main(int argc, char *argv[])
clockid_t clkid;
int adjfreq = 0x7fffffff;
int adjtime = 0;
+ int adjns = 0;
int capabilities = 0;
int extts = 0;
int flagtest = 0;
@@ -186,7 +188,7 @@ int main(int argc, char *argv[])

progname = strrchr(argv[0], '/');
progname = progname ? 1+progname : argv[0];
- while (EOF != (c = getopt(argc, argv, "cd:e:f:ghH:i:k:lL:p:P:sSt:T:w:z"))) {
+ while (EOF != (c = getopt(argc, argv, "cd:e:f:ghH:i:k:lL:n:p:P:sSt:T:w:z"))) {
switch (c) {
case 'c':
capabilities = 1;
@@ -223,6 +225,9 @@ int main(int argc, char *argv[])
return -1;
}
break;
+ case 'n':
+ adjns = atoi(optarg);
+ break;
case 'p':
perout = atoll(optarg);
break;
@@ -305,11 +310,16 @@ int main(int argc, char *argv[])
}
}

- if (adjtime) {
+ if (adjtime || adjns) {
memset(&tx, 0, sizeof(tx));
- tx.modes = ADJ_SETOFFSET;
+ tx.modes = ADJ_SETOFFSET | ADJ_NANO;
tx.time.tv_sec = adjtime;
- tx.time.tv_usec = 0;
+ tx.time.tv_usec = adjns;
+ while (tx.time.tv_usec < 0) {
+ tx.time.tv_sec -= 1;
+ tx.time.tv_usec += 1000000000;
+ }
+
if (clock_adjtime(clkid, &tx) < 0) {
perror("clock_adjtime");
} else {
--
2.51.0