This ioctl uses cross timestamping for a more accurate measurement of
the offset. It is supported on some onboard Intel NICs using the e1000e
driver and a virtual PHC with the ptp_kvm driver.
Signed-off-by: Miroslav Lichvar <mlich...@redhat.com>
---
sysoff.c | 21 +++++++++++++++++++++
sysoff.h | 1 +
2 files changed, 22 insertions(+)
diff --git a/sysoff.c b/sysoff.c
index f709a9b..9f65d95 100644
--- a/sysoff.c
+++ b/sysoff.c
@@ -22,6 +22,7 @@
#include <sys/ioctl.h>
#include <linux/ptp_clock.h>
+#include "print.h"
#include "sysoff.h"
#define NS_PER_SEC 1000000000LL
@@ -39,6 +40,23 @@ static struct {
uint64_t timestamp;
} samples[PTP_MAX_SAMPLES];
+static int sysoff_precise(int fd, int64_t *result, uint64_t *ts)
+{
+#ifdef PTP_SYS_OFFSET_PRECISE
+ struct ptp_sys_offset_precise pso;
+ memset(&pso, 0, sizeof(pso));
+ if (ioctl(fd, PTP_SYS_OFFSET_PRECISE, &pso)) {
+ pr_debug("ioctl PTP_SYS_OFFSET_PRECISE: %m");
+ return SYSOFF_RUN_TIME_MISSING;
+ }
+ *result = pctns(&pso.sys_realtime) - pctns(&pso.device);
+ *ts = pctns(&pso.sys_realtime);
+ return SYSOFF_PRECISE;
+#else
+ return SYSOFF_COMPILE_TIME_MISSING;
+#endif
+}
+
static void insertion_sort(int length, int64_t interval, int64_t offset,
uint64_t ts)
{
int i = length - 1;
@@ -91,6 +109,9 @@ int sysoff_measure(int fd, int method, int n_samples,
int64_t *result, uint64_t *ts, int64_t *delay)
{
switch (method) {
+ case SYSOFF_PRECISE:
+ *delay = 0;
+ return sysoff_precise(fd, result, ts);
case SYSOFF_BASIC:
return sysoff_basic(fd, n_samples, result, ts, delay);
}
diff --git a/sysoff.h b/sysoff.h
index 02ecdfa..37f7353 100644
--- a/sysoff.h
+++ b/sysoff.h
@@ -23,6 +23,7 @@
enum {
SYSOFF_COMPILE_TIME_MISSING = -2,
SYSOFF_RUN_TIME_MISSING = -1,
+ SYSOFF_PRECISE,
SYSOFF_BASIC,
SYSOFF_LAST,
};
--
2.17.2
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