The read_phc function implemented in phc2sys.c is used to perform clock
comparison between two arbitrary clocks using clock_gettime.
This support is used to allow phc2sys to work on any pair of clocks and
is implemented in a very similar manner as the kernel PTP_SYS_OFFSET
ioctls.
Make this function easier to re-use by moving it out of phc2sys.c and
into a more accessible location. clockadj.c seems like a reasonable
location as this file has many functions which deal with clockid_t
values, and this functionality is tangentially related to adjusting
clocks.
Moving this function will allow using it in the phc_ctl program in a
future change.
Signed-off-by: Jacob Keller <jacob.e.kel...@intel.com>
---
clockadj.c | 31 +++++++++++++++++++++++++++++++
clockadj.h | 16 ++++++++++++++++
phc2sys.c | 44 ++++++++------------------------------------
3 files changed, 55 insertions(+), 36 deletions(-)
diff --git a/clockadj.c b/clockadj.c
index b5c78cd112ff..c78017049a0e 100644
--- a/clockadj.c
+++ b/clockadj.c
@@ -139,6 +139,37 @@ int clockadj_max_freq(clockid_t clkid)
return f;
}
+int clockadj_compare(clockid_t clkid, clockid_t sysclk, int readings,
+ int64_t *offset, uint64_t *ts, int64_t *delay)
+{
+ struct timespec tdst1, tdst2, tsrc;
+ int i;
+ int64_t interval, best_interval = INT64_MAX;
+
+ /* Pick the quickest clkid reading. */
+ for (i = 0; i < readings; i++) {
+ if (clock_gettime(sysclk, &tdst1) ||
+ clock_gettime(clkid, &tsrc) ||
+ clock_gettime(sysclk, &tdst2)) {
+ pr_err("failed to read clock: %m");
+ return 0;
+ }
+
+ interval = (tdst2.tv_sec - tdst1.tv_sec) * NS_PER_SEC +
+ tdst2.tv_nsec - tdst1.tv_nsec;
+
+ if (best_interval > interval) {
+ best_interval = interval;
+ *offset = (tdst1.tv_sec - tsrc.tv_sec) * NS_PER_SEC +
+ tdst1.tv_nsec - tsrc.tv_nsec + interval / 2;
+ *ts = tdst2.tv_sec * NS_PER_SEC + tdst2.tv_nsec;
+ }
+ }
+ *delay = best_interval;
+
+ return 1;
+}
+
void sysclk_set_leap(int leap)
{
clockid_t clkid = CLOCK_REALTIME;
diff --git a/clockadj.h b/clockadj.h
index 43325c8d5d15..995b2af11894 100644
--- a/clockadj.h
+++ b/clockadj.h
@@ -63,6 +63,22 @@ void clockadj_step(clockid_t clkid, int64_t step);
*/
int clockadj_max_freq(clockid_t clkid);
+/**
+ * Compare offset between two clocks
+ * @param clkid A clock ID obtained using phc_open() or CLOCK_REALTIME
+ * @param sysclk A clock ID obtained using phc_open() or CLOCK_REALTIME
+ * @readings Number of readings to try
+ * @offset On return, the nanoseconds offset between the clocks
+ * @ts On return, the time of sysclk in nanoseconds that was used
+ * @delay On return, the interval between two reads of sysclk
+ *
+ * Compare the offset between two clocks in a similar manner as the
+ * PTP_SYS_OFFSET ioctls. Returns the difference between sysclk and clkid by
+ * performing multiple reads of sysclk with a read of clkid between.
+ */
+int clockadj_compare(clockid_t clkid, clockid_t sysclk, int readings,
+ int64_t *offset, uint64_t *ts, int64_t *delay);
+
/**
* Set the system clock to insert/delete leap second at midnight.
* @param leap +1 to insert leap second, -1 to delete leap second,
diff --git a/phc2sys.c b/phc2sys.c
index 6815c3dee8a0..5a14b0da8786 100644
--- a/phc2sys.c
+++ b/phc2sys.c
@@ -470,37 +470,6 @@ static void reconfigure(struct phc2sys_private *priv)
pr_info("selecting %s as the master clock", src->device);
}
-static int read_phc(clockid_t clkid, clockid_t sysclk, int readings,
- int64_t *offset, uint64_t *ts, int64_t *delay)
-{
- struct timespec tdst1, tdst2, tsrc;
- int i;
- int64_t interval, best_interval = INT64_MAX;
-
- /* Pick the quickest clkid reading. */
- for (i = 0; i < readings; i++) {
- if (clock_gettime(sysclk, &tdst1) ||
- clock_gettime(clkid, &tsrc) ||
- clock_gettime(sysclk, &tdst2)) {
- pr_err("failed to read clock: %m");
- return 0;
- }
-
- interval = (tdst2.tv_sec - tdst1.tv_sec) * NS_PER_SEC +
- tdst2.tv_nsec - tdst1.tv_nsec;
-
- if (best_interval > interval) {
- best_interval = interval;
- *offset = (tdst1.tv_sec - tsrc.tv_sec) * NS_PER_SEC +
- tdst1.tv_nsec - tsrc.tv_nsec + interval / 2;
- *ts = tdst2.tv_sec * NS_PER_SEC + tdst2.tv_nsec;
- }
- }
- *delay = best_interval;
-
- return 1;
-}
-
static int64_t get_sync_offset(struct phc2sys_private *priv, struct clock *dst)
{
int direction = priv->forced_sync_offset;
@@ -662,8 +631,10 @@ static int do_pps_loop(struct phc2sys_private *priv,
struct clock *clock,
/* If a PHC is available, use it to get the whole number
of seconds in the offset and PPS for the rest. */
if (src != CLOCK_INVALID) {
- if (!read_phc(src, clock->clkid, priv->phc_readings,
- &phc_offset, &phc_ts, &phc_delay))
+ if (!clockadj_compare(src, clock->clkid,
+ priv->phc_readings,
+ &phc_offset, &phc_ts,
+ &phc_delay))
return -1;
/* Convert the time stamp to the PHC time. */
@@ -764,9 +735,10 @@ static int do_loop(struct phc2sys_private *priv)
ts += offset;
} else {
/* use phc */
- if (!read_phc(priv->master->clkid, clock->clkid,
- priv->phc_readings,
- &offset, &ts, &delay))
+ if (!clockadj_compare(priv->master->clkid,
+ clock->clkid,
+ priv->phc_readings,
+ &offset, &ts, &delay))
continue;
}
update_clock(priv, clock, offset, ts, delay);
--
2.31.1.331.gb0c09ab8796f
_______________________________________________
Linuxptp-devel mailing list
Linuxptp-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
