Messages in this thread Patch in this message | | | Date | Wed, 17 Apr 2024 21:27:06 -0700 | Subject | [PATCHv2 next] ptp: update gettimex64 to provide ts optionally in mono-raw base. | From | Mahesh Bandewar <> |
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The current implementation of PTP_SYS_OFFSET_EXTENDED provides PHC reads in the form of [pre-TS, PHC, post-TS]. These pre and post timestamps are useful to measure the width of the PHC read. However, the current implementation provides these timestamps in CLOCK_REALTIME only. Since CLOCK_REALTIME is disciplined by NTP or NTP-like service(s), the value is subjected to change. This makes some applications that are very sensitive to time change have these timestamps delivered in different time-base.
This patch updates the gettimex64 / ioctl op PTP_SYS_OFFSET_EXTENDED to provide these (sandwich) timestamps optionally in CLOCK_MONOTONIC_RAW timebase while maintaining the default behavior or giving them in CLOCK_REALTIME.
~# testptp -d /dev/ptp0 -x 3 -y raw extended timestamp request returned 3 samples sample # 0: mono-raw time before: 371.548640128 phc time: 371.579671788 mono-raw time after: 371.548640912 sample # 1: mono-raw time before: 371.548642104 phc time: 371.579673346 mono-raw time after: 371.548642490 sample # 2: mono-raw time before: 371.548643320 phc time: 371.579674652 mono-raw time after: 371.548643756 ~# testptp -d /dev/ptp0 -x 3 -y real extended timestamp request returned 3 samples sample # 0: system time before: 1713243413.403474250 phc time: 385.699915490 system time after: 1713243413.403474948 sample # 1: system time before: 1713243413.403476220 phc time: 385.699917168 system time after: 1713243413.403476642 sample # 2: system time before: 1713243413.403477555 phc time: 385.699918442 system time after: 1713243413.403477961 ~#
Signed-off-by: Mahesh Bandewar <maheshb@google.com> --- v1 -> v2 * Code-style fixes
drivers/ptp/ptp_chardev.c | 7 +++++-- include/linux/ptp_clock_kernel.h | 30 ++++++++++++++++++++++++++---- include/uapi/linux/ptp_clock.h | 7 ++++++- 3 files changed, 37 insertions(+), 7 deletions(-)
diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c index 7513018c9f9a..c109109c9e8e 100644 --- a/drivers/ptp/ptp_chardev.c +++ b/drivers/ptp/ptp_chardev.c @@ -358,11 +358,14 @@ long ptp_ioctl(struct posix_clock_context *pccontext, unsigned int cmd, extoff = NULL; break; } - if (extoff->n_samples > PTP_MAX_SAMPLES - || extoff->rsv[0] || extoff->rsv[1] || extoff->rsv[2]) { + if (extoff->n_samples > PTP_MAX_SAMPLES || + extoff->rsv[0] || extoff->rsv[1] || + (extoff->clockid != CLOCK_REALTIME && + extoff->clockid != CLOCK_MONOTONIC_RAW)) { err = -EINVAL; break; } + sts.clockid = extoff->clockid; for (i = 0; i < extoff->n_samples; i++) { err = ptp->info->gettimex64(ptp->info, &ts, &sts); if (err) diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h index 6e4b8206c7d0..7563da6db09b 100644 --- a/include/linux/ptp_clock_kernel.h +++ b/include/linux/ptp_clock_kernel.h @@ -47,10 +47,12 @@ struct system_device_crosststamp; * struct ptp_system_timestamp - system time corresponding to a PHC timestamp * @pre_ts: system timestamp before capturing PHC * @post_ts: system timestamp after capturing PHC + * @clockid: clockid used for cpaturing timestamp */ struct ptp_system_timestamp { struct timespec64 pre_ts; struct timespec64 post_ts; + clockid_t clockid; }; /** @@ -457,14 +459,34 @@ static inline ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, static inline void ptp_read_system_prets(struct ptp_system_timestamp *sts) { - if (sts) - ktime_get_real_ts64(&sts->pre_ts); + if (sts) { + switch (sts->clockid) { + case CLOCK_REALTIME: + ktime_get_real_ts64(&sts->pre_ts); + break; + case CLOCK_MONOTONIC_RAW: + ktime_get_raw_ts64(&sts->pre_ts); + break; + default: + break; + } + } } static inline void ptp_read_system_postts(struct ptp_system_timestamp *sts) { - if (sts) - ktime_get_real_ts64(&sts->post_ts); + if (sts) { + switch (sts->clockid) { + case CLOCK_REALTIME: + ktime_get_real_ts64(&sts->post_ts); + break; + case CLOCK_MONOTONIC_RAW: + ktime_get_raw_ts64(&sts->post_ts); + break; + default: + break; + } + } } #endif diff --git a/include/uapi/linux/ptp_clock.h b/include/uapi/linux/ptp_clock.h index 053b40d642de..fc5825e72330 100644 --- a/include/uapi/linux/ptp_clock.h +++ b/include/uapi/linux/ptp_clock.h @@ -157,7 +157,12 @@ struct ptp_sys_offset { struct ptp_sys_offset_extended { unsigned int n_samples; /* Desired number of measurements. */ - unsigned int rsv[3]; /* Reserved for future use. */ + /* The original implementation provided timestamps (always) in + * REALTIME clock-base. Since CLOCK_REALTIME is 0, adding + * clockid doesn't break backward compatibility. + */ + clockid_t clockid; /* One of the supported clock-ids */ + unsigned int rsv[2]; /* Reserved for future use. */ /* * Array of [system, phc, system] time stamps. The kernel will provide * 3*n_samples time stamps. -- 2.44.0.683.g7961c838ac-goog
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