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authorChristopher S. Hall <christopher.s.hall@intel.com>2016-02-22 14:15:25 +0300
committerJohn Stultz <john.stultz@linaro.org>2016-03-04 01:23:43 +0300
commit719f1aa4a67199a3c4c68a03f94e5ec44d9d5f82 (patch)
tree0a6cdf499ae615abf88e8d826e0c63c431f54bdb /include/linux/ptp_clock_kernel.h
parentf9677e0f83080bb4186865868c359e72e1fac1ea (diff)
downloadlinux-719f1aa4a67199a3c4c68a03f94e5ec44d9d5f82.tar.xz
ptp: Add PTP_SYS_OFFSET_PRECISE for driver crosstimestamping
Currently, network /system cross-timestamping is performed in the PTP_SYS_OFFSET ioctl. The PTP clock driver reads gettimeofday() and the gettime64() callback provided by the driver. The cross-timestamp is best effort where the latency between the capture of system time (getnstimeofday()) and the device time (driver callback) may be significant. The getcrosststamp() callback and corresponding PTP_SYS_OFFSET_PRECISE ioctl allows the driver to perform this device/system correlation when for example cross timestamp hardware is available. Modern Intel systems can do this for onboard Ethernet controllers using the ART counter. There is virtually zero latency between captures of the ART and network device clock. The capabilities ioctl (PTP_CLOCK_GETCAPS), is augmented allowing applications to query whether or not drivers implement the getcrosststamp callback, providing more precise cross timestamping. Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: kevin.b.stanton@intel.com Cc: kevin.j.clarke@intel.com Cc: hpa@zytor.com Cc: jeffrey.t.kirsher@intel.com Cc: netdev@vger.kernel.org Acked-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com> [jstultz: Commit subject tweaks] Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'include/linux/ptp_clock_kernel.h')
-rw-r--r--include/linux/ptp_clock_kernel.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index b8b73066d137..6b15e168148a 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -38,6 +38,7 @@ struct ptp_clock_request {
};
};
+struct system_device_crosststamp;
/**
* struct ptp_clock_info - decribes a PTP hardware clock
*
@@ -67,6 +68,11 @@ struct ptp_clock_request {
* @gettime64: Reads the current time from the hardware clock.
* parameter ts: Holds the result.
*
+ * @getcrosststamp: Reads the current time from the hardware clock and
+ * system clock simultaneously.
+ * parameter cts: Contains timestamp (device,system) pair,
+ * where system time is realtime and monotonic.
+ *
* @settime64: Set the current time on the hardware clock.
* parameter ts: Time value to set.
*
@@ -105,6 +111,8 @@ struct ptp_clock_info {
int (*adjfreq)(struct ptp_clock_info *ptp, s32 delta);
int (*adjtime)(struct ptp_clock_info *ptp, s64 delta);
int (*gettime64)(struct ptp_clock_info *ptp, struct timespec64 *ts);
+ int (*getcrosststamp)(struct ptp_clock_info *ptp,
+ struct system_device_crosststamp *cts);
int (*settime64)(struct ptp_clock_info *p, const struct timespec64 *ts);
int (*enable)(struct ptp_clock_info *ptp,
struct ptp_clock_request *request, int on);