diff --git a/hwclock.c b/hwclock.c new file mode 100644 index 0000000..e987daa --- /dev/null +++ b/hwclock.c @@ -0,0 +1,202 @@ +/* + chronyd/chronyc - Programs for keeping computer clocks accurate. + + ********************************************************************** + * Copyright (C) Miroslav Lichvar 2016 + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of version 2 of the GNU General Public License as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + * + ********************************************************************** + + ======================================================================= + + Tracking of hardware clocks (e.g. RTC, PHC) + */ + +#include "config.h" + +#include "sysincl.h" + +#include "array.h" +#include "hwclock.h" +#include "local.h" +#include "logging.h" +#include "memory.h" +#include "regress.h" +#include "util.h" + +/* Maximum number of samples per clock */ +#define MAX_SAMPLES 16 + +/* Minimum interval between samples (in seconds) */ +#define MIN_SAMPLE_SEPARATION 1.0 + +struct HCL_Instance_Record { + /* HW and local reference timestamp */ + struct timespec hw_ref; + struct timespec local_ref; + + /* Samples stored as intervals (uncorrected for frequency error) + relative to local_ref and hw_ref */ + double x_data[MAX_SAMPLES]; + double y_data[MAX_SAMPLES]; + + /* Number of samples */ + int n_samples; + + /* Flag indicating the offset and frequency values are valid */ + int valid_coefs; + + /* Estimated offset and frequency of HW clock relative to local clock */ + double offset; + double frequency; +}; + +/* ================================================== */ + +static void +handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq, + double doffset, LCL_ChangeType change_type, void *anything) +{ + HCL_Instance clock; + double delta; + + clock = anything; + + if (clock->n_samples) + UTI_AdjustTimespec(&clock->local_ref, cooked, &clock->local_ref, &delta, dfreq, doffset); + if (clock->valid_coefs) + clock->frequency /= 1.0 - dfreq; +} + +/* ================================================== */ + +HCL_Instance +HCL_CreateInstance(void) +{ + HCL_Instance clock; + + clock = MallocNew(struct HCL_Instance_Record); + clock->x_data[0] = 0.0; + clock->y_data[0] = 0.0; + clock->n_samples = 0; + clock->valid_coefs = 0; + + LCL_AddParameterChangeHandler(handle_slew, clock); + + return clock; +} + +/* ================================================== */ + +void HCL_DestroyInstance(HCL_Instance clock) +{ + LCL_RemoveParameterChangeHandler(handle_slew, clock); + Free(clock); +} + +/* ================================================== */ + +int +HCL_NeedsNewSample(HCL_Instance clock, struct timespec *now) +{ + if (!clock->n_samples || + fabs(UTI_DiffTimespecsToDouble(now, &clock->local_ref) >= MIN_SAMPLE_SEPARATION)) + return 1; + + return 0; +} + +/* ================================================== */ + +void +HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts, + struct timespec *local_ts, double err) +{ + double hw_delta, local_delta, local_freq, raw_freq; + int i, n_runs, best_start; + + local_freq = 1.0 - LCL_ReadAbsoluteFrequency() / 1.0e6; + + /* Shift old samples */ + if (clock->n_samples) { + if (clock->n_samples >= MAX_SAMPLES) + clock->n_samples--; + + hw_delta = UTI_DiffTimespecsToDouble(hw_ts, &clock->hw_ref); + local_delta = UTI_DiffTimespecsToDouble(local_ts, &clock->local_ref) / local_freq; + + if (hw_delta <= 0.0 || local_delta < MIN_SAMPLE_SEPARATION / 2.0) { + clock->n_samples = 0; + DEBUG_LOG(LOGF_HwClocks, "HW clock reset interval=%f", local_delta); + } + + for (i = clock->n_samples; i > 0; i--) { + clock->y_data[i] = clock->y_data[i - 1] - hw_delta; + clock->x_data[i] = clock->x_data[i - 1] - local_delta; + } + } + + clock->n_samples++; + clock->hw_ref = *hw_ts; + clock->local_ref = *local_ts; + + /* Get new coefficients */ + clock->valid_coefs = + RGR_FindBestRobustRegression(clock->x_data, clock->y_data, clock->n_samples, + 1.0e-9, &clock->offset, &raw_freq, &n_runs, &best_start); + + if (!clock->valid_coefs) { + DEBUG_LOG(LOGF_HwClocks, "HW clock needs more samples"); + return; + } + + clock->frequency = raw_freq / local_freq; + + /* Drop unneeded samples */ + clock->n_samples -= best_start; + + /* If the fit doesn't cross the error interval of the last sample, throw away + all previous samples and keep only the frequency estimate */ + if (fabs(clock->offset) > err) { + DEBUG_LOG(LOGF_HwClocks, "HW clock reset offset=%e", clock->offset); + clock->offset = 0.0; + clock->n_samples = 1; + } + + DEBUG_LOG(LOGF_HwClocks, "HW clock samples=%d offset=%e freq=%.9e raw_freq=%.9e err=%e ref_diff=%e", + clock->n_samples, clock->offset, clock->frequency, raw_freq, err, + UTI_DiffTimespecsToDouble(&clock->hw_ref, &clock->local_ref)); +} + +/* ================================================== */ + +int +HCL_CookTime(HCL_Instance clock, struct timespec *raw, struct timespec *cooked, double *err) +{ + double offset, elapsed; + + if (!clock->valid_coefs) + return 0; + + elapsed = UTI_DiffTimespecsToDouble(raw, &clock->hw_ref); + offset = clock->offset + elapsed / clock->frequency; + UTI_AddDoubleToTimespec(&clock->local_ref, offset, cooked); + + /* Estimation of the error is not implemented yet */ + if (err) + *err = 0.0; + + return 1; +} diff --git a/hwclock.h b/hwclock.h new file mode 100644 index 0000000..11a79b0 --- /dev/null +++ b/hwclock.h @@ -0,0 +1,48 @@ +/* + chronyd/chronyc - Programs for keeping computer clocks accurate. + + ********************************************************************** + * Copyright (C) Miroslav Lichvar 2016 + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of version 2 of the GNU General Public License as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + * + ********************************************************************** + + ======================================================================= + + Header for tracking of hardware clocks */ + +#ifndef GOT_HWCLOCK_H +#define GOT_HWCLOCK_H + +typedef struct HCL_Instance_Record *HCL_Instance; + +/* Create a new HW clock instance */ +extern HCL_Instance HCL_CreateInstance(void); + +/* Destroy a HW clock instance */ +extern void HCL_DestroyInstance(HCL_Instance clock); + +/* Check if a new sample should be accumulated at this time */ +extern int HCL_NeedsNewSample(HCL_Instance clock, struct timespec *now); + +/* Accumulate a new sample */ +extern void HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts, + struct timespec *local_ts, double err); + +/* Convert raw hardware time to cooked local time */ +extern int HCL_CookTime(HCL_Instance clock, struct timespec *raw, struct timespec *cooked, + double *err); + +#endif diff --git a/logging.h b/logging.h index 41d640e..cc8beee 100644 --- a/logging.h +++ b/logging.h @@ -116,6 +116,7 @@ typedef enum { LOGF_TempComp, LOGF_RtcLinux, LOGF_Refclock, + LOGF_HwClocks, LOGF_Smooth, } LOG_Facility;