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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>
201 lines
6.5 KiB
C
201 lines
6.5 KiB
C
/*
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* PTP 1588 clock support
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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_KERNEL_H_
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#define _PTP_CLOCK_KERNEL_H_
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#include <linux/device.h>
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#include <linux/pps_kernel.h>
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#include <linux/ptp_clock.h>
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struct ptp_clock_request {
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enum {
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PTP_CLK_REQ_EXTTS,
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PTP_CLK_REQ_PEROUT,
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PTP_CLK_REQ_PPS,
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} type;
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union {
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struct ptp_extts_request extts;
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struct ptp_perout_request perout;
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};
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};
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struct system_device_crosststamp;
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/**
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* struct ptp_clock_info - decribes a PTP hardware clock
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*
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* @owner: The clock driver should set to THIS_MODULE.
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* @name: A short "friendly name" to identify the clock and to
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* help distinguish PHY based devices from MAC based ones.
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* The string is not meant to be a unique id.
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* @max_adj: The maximum possible frequency adjustment, in parts per billon.
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* @n_alarm: The number of programmable alarms.
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* @n_ext_ts: The number of external time stamp channels.
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* @n_per_out: The number of programmable periodic signals.
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* @n_pins: The number of programmable pins.
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* @pps: Indicates whether the clock supports a PPS callback.
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* @pin_config: Array of length 'n_pins'. If the number of
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* programmable pins is nonzero, then drivers must
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* allocate and initialize this array.
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*
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* clock operations
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*
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* @adjfreq: Adjusts the frequency of the hardware clock.
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* parameter delta: Desired frequency offset from nominal frequency
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* in parts per billion
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*
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* @adjtime: Shifts the time of the hardware clock.
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* parameter delta: Desired change in nanoseconds.
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*
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* @gettime64: Reads the current time from the hardware clock.
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* parameter ts: Holds the result.
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*
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* @getcrosststamp: Reads the current time from the hardware clock and
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* system clock simultaneously.
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* parameter cts: Contains timestamp (device,system) pair,
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* where system time is realtime and monotonic.
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*
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* @settime64: Set the current time on the hardware clock.
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* parameter ts: Time value to set.
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*
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* @enable: Request driver to enable or disable an ancillary feature.
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* parameter request: Desired resource to enable or disable.
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* parameter on: Caller passes one to enable or zero to disable.
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*
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* @verify: Confirm that a pin can perform a given function. The PTP
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* Hardware Clock subsystem maintains the 'pin_config'
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* array on behalf of the drivers, but the PHC subsystem
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* assumes that every pin can perform every function. This
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* hook gives drivers a way of telling the core about
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* limitations on specific pins. This function must return
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* zero if the function can be assigned to this pin, and
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* nonzero otherwise.
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* parameter pin: index of the pin in question.
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* parameter func: the desired function to use.
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* parameter chan: the function channel index to use.
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*
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* Drivers should embed their ptp_clock_info within a private
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* structure, obtaining a reference to it using container_of().
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*
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* The callbacks must all return zero on success, non-zero otherwise.
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*/
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struct ptp_clock_info {
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struct module *owner;
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char name[16];
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s32 max_adj;
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int n_alarm;
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int n_ext_ts;
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int n_per_out;
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int n_pins;
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int pps;
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struct ptp_pin_desc *pin_config;
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int (*adjfreq)(struct ptp_clock_info *ptp, s32 delta);
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int (*adjtime)(struct ptp_clock_info *ptp, s64 delta);
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int (*gettime64)(struct ptp_clock_info *ptp, struct timespec64 *ts);
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int (*getcrosststamp)(struct ptp_clock_info *ptp,
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struct system_device_crosststamp *cts);
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int (*settime64)(struct ptp_clock_info *p, const struct timespec64 *ts);
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int (*enable)(struct ptp_clock_info *ptp,
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struct ptp_clock_request *request, int on);
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int (*verify)(struct ptp_clock_info *ptp, unsigned int pin,
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enum ptp_pin_function func, unsigned int chan);
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};
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struct ptp_clock;
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/**
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* ptp_clock_register() - register a PTP hardware clock driver
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*
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* @info: Structure describing the new clock.
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* @parent: Pointer to the parent device of the new clock.
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*/
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extern struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
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struct device *parent);
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/**
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* ptp_clock_unregister() - unregister a PTP hardware clock driver
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*
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* @ptp: The clock to remove from service.
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*/
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extern int ptp_clock_unregister(struct ptp_clock *ptp);
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enum ptp_clock_events {
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PTP_CLOCK_ALARM,
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PTP_CLOCK_EXTTS,
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PTP_CLOCK_PPS,
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PTP_CLOCK_PPSUSR,
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};
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/**
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* struct ptp_clock_event - decribes a PTP hardware clock event
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*
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* @type: One of the ptp_clock_events enumeration values.
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* @index: Identifies the source of the event.
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* @timestamp: When the event occurred (%PTP_CLOCK_EXTTS only).
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* @pps_times: When the event occurred (%PTP_CLOCK_PPSUSR only).
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*/
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struct ptp_clock_event {
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int type;
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int index;
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union {
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u64 timestamp;
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struct pps_event_time pps_times;
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};
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};
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/**
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* ptp_clock_event() - notify the PTP layer about an event
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*
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* @ptp: The clock obtained from ptp_clock_register().
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* @event: Message structure describing the event.
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*/
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extern void ptp_clock_event(struct ptp_clock *ptp,
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struct ptp_clock_event *event);
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/**
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* ptp_clock_index() - obtain the device index of a PTP clock
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*
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* @ptp: The clock obtained from ptp_clock_register().
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*/
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extern int ptp_clock_index(struct ptp_clock *ptp);
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/**
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* ptp_find_pin() - obtain the pin index of a given auxiliary function
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*
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* @ptp: The clock obtained from ptp_clock_register().
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* @func: One of the ptp_pin_function enumerated values.
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* @chan: The particular functional channel to find.
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* Return: Pin index in the range of zero to ptp_clock_caps.n_pins - 1,
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* or -1 if the auxiliary function cannot be found.
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*/
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int ptp_find_pin(struct ptp_clock *ptp,
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enum ptp_pin_function func, unsigned int chan);
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#endif
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