ed379b4028
Check the sanity of the synchronized clock by comparing its uncorrected frequency with the system monotonic clock. When the measured frequency offset is larger than the value of the sanity_freq_limit option (20% by default), a warning message will be printed and the servo will be reset. Setting the option to zero disables the check. This is useful to detect when the clock is broken or adjusted by another program. Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
65 lines
2.3 KiB
C
65 lines
2.3 KiB
C
/**
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* @file clockcheck.h
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* @brief Implements clock sanity checking.
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* @note Copyright (C) 2013 Miroslav Lichvar <mlichvar@redhat.com>
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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 along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef HAVE_CLOCKCHECK_H
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#define HAVE_CLOCKCHECK_H
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#include <stdint.h>
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/** Opaque type */
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struct clockcheck;
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/**
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* Create a new instance of a clock sanity check.
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* @param freq_limit The maximum allowed frequency offset between uncorrected
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* clock and the system monotonic clock in ppb.
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* @return A pointer to a new clock check on success, NULL otherwise.
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*/
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struct clockcheck *clockcheck_create(int freq_limit);
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/**
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* Perform the sanity check on a time stamp.
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* @param cc Pointer to a clock check obtained via @ref clockcheck_create().
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* @param ts Time stamp made by the clock in nanoseconds.
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* @return Zero if ts passed the check, non-zero otherwise.
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*/
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int clockcheck_sample(struct clockcheck *cc, uint64_t ts);
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/**
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* Inform clock check about changes in current frequency of the clock.
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* @param cc Pointer to a clock check obtained via @ref clockcheck_create().
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* @param freq Frequency correction applied to the clock in ppb.
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*/
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void clockcheck_set_freq(struct clockcheck *cc, int freq);
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/**
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* Inform clock check that the clock was stepped.
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* @param cc Pointer to a clock check obtained via @ref clockcheck_create().
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* @param step Step correction applied to the clock in nanoseconds.
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*/
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void clockcheck_step(struct clockcheck *cc, int64_t step);
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/**
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* Destroy a clock check.
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* @param cc Pointer to a clock check obtained via @ref clockcheck_create().
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*/
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void clockcheck_destroy(struct clockcheck *cc);
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#endif
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