![Christopher S. Hall](/assets/img/avatar_default.png)
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>
147 lines
4.7 KiB
C
147 lines
4.7 KiB
C
/*
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* PTP 1588 clock support - user space interface
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*
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* Copyright (C) 2010 OMICRON electronics GmbH
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef _PTP_CLOCK_H_
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#define _PTP_CLOCK_H_
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#include <linux/ioctl.h>
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#include <linux/types.h>
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/* PTP_xxx bits, for the flags field within the request structures. */
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#define PTP_ENABLE_FEATURE (1<<0)
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#define PTP_RISING_EDGE (1<<1)
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#define PTP_FALLING_EDGE (1<<2)
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/*
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* struct ptp_clock_time - represents a time value
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*
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* The sign of the seconds field applies to the whole value. The
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* nanoseconds field is always unsigned. The reserved field is
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* included for sub-nanosecond resolution, should the demand for
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* this ever appear.
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*
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*/
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struct ptp_clock_time {
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__s64 sec; /* seconds */
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__u32 nsec; /* nanoseconds */
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__u32 reserved;
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};
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struct ptp_clock_caps {
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int max_adj; /* Maximum frequency adjustment in parts per billon. */
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int n_alarm; /* Number of programmable alarms. */
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int n_ext_ts; /* Number of external time stamp channels. */
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int n_per_out; /* Number of programmable periodic signals. */
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int pps; /* Whether the clock supports a PPS callback. */
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int n_pins; /* Number of input/output pins. */
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/* Whether the clock supports precise system-device cross timestamps */
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int cross_timestamping;
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int rsv[13]; /* Reserved for future use. */
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};
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struct ptp_extts_request {
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unsigned int index; /* Which channel to configure. */
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unsigned int flags; /* Bit field for PTP_xxx flags. */
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unsigned int rsv[2]; /* Reserved for future use. */
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};
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struct ptp_perout_request {
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struct ptp_clock_time start; /* Absolute start time. */
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struct ptp_clock_time period; /* Desired period, zero means disable. */
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unsigned int index; /* Which channel to configure. */
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unsigned int flags; /* Reserved for future use. */
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unsigned int rsv[4]; /* Reserved for future use. */
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};
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#define PTP_MAX_SAMPLES 25 /* Maximum allowed offset measurement samples. */
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struct ptp_sys_offset {
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unsigned int n_samples; /* Desired number of measurements. */
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unsigned int rsv[3]; /* Reserved for future use. */
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/*
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* Array of interleaved system/phc time stamps. The kernel
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* will provide 2*n_samples + 1 time stamps, with the last
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* one as a system time stamp.
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*/
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struct ptp_clock_time ts[2 * PTP_MAX_SAMPLES + 1];
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};
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struct ptp_sys_offset_precise {
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struct ptp_clock_time device;
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struct ptp_clock_time sys_realtime;
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struct ptp_clock_time sys_monoraw;
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unsigned int rsv[4]; /* Reserved for future use. */
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};
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enum ptp_pin_function {
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PTP_PF_NONE,
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PTP_PF_EXTTS,
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PTP_PF_PEROUT,
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PTP_PF_PHYSYNC,
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};
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struct ptp_pin_desc {
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/*
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* Hardware specific human readable pin name. This field is
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* set by the kernel during the PTP_PIN_GETFUNC ioctl and is
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* ignored for the PTP_PIN_SETFUNC ioctl.
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*/
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char name[64];
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/*
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* Pin index in the range of zero to ptp_clock_caps.n_pins - 1.
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*/
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unsigned int index;
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/*
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* Which of the PTP_PF_xxx functions to use on this pin.
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*/
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unsigned int func;
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/*
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* The specific channel to use for this function.
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* This corresponds to the 'index' field of the
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* PTP_EXTTS_REQUEST and PTP_PEROUT_REQUEST ioctls.
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*/
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unsigned int chan;
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/*
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* Reserved for future use.
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*/
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unsigned int rsv[5];
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};
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#define PTP_CLK_MAGIC '='
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#define PTP_CLOCK_GETCAPS _IOR(PTP_CLK_MAGIC, 1, struct ptp_clock_caps)
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#define PTP_EXTTS_REQUEST _IOW(PTP_CLK_MAGIC, 2, struct ptp_extts_request)
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#define PTP_PEROUT_REQUEST _IOW(PTP_CLK_MAGIC, 3, struct ptp_perout_request)
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#define PTP_ENABLE_PPS _IOW(PTP_CLK_MAGIC, 4, int)
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#define PTP_SYS_OFFSET _IOW(PTP_CLK_MAGIC, 5, struct ptp_sys_offset)
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#define PTP_PIN_GETFUNC _IOWR(PTP_CLK_MAGIC, 6, struct ptp_pin_desc)
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#define PTP_PIN_SETFUNC _IOW(PTP_CLK_MAGIC, 7, struct ptp_pin_desc)
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#define PTP_SYS_OFFSET_PRECISE \
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_IOWR(PTP_CLK_MAGIC, 8, struct ptp_sys_offset_precise)
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struct ptp_extts_event {
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struct ptp_clock_time t; /* Time event occured. */
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unsigned int index; /* Which channel produced the event. */
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unsigned int flags; /* Reserved for future use. */
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unsigned int rsv[2]; /* Reserved for future use. */
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};
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#endif
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