/*
chronyd/chronyc - Programs for keeping computer clocks accurate.
**********************************************************************
* Copyright (C) Miroslav Lichvar 2014-2015
*
* 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.
*
**********************************************************************
=======================================================================
Generic driver functions to complete system-specific drivers
*/
#include "config.h"
#include "sysincl.h"
#include "sys_generic.h"
#include "conf.h"
#include "local.h"
#include "localp.h"
#include "logging.h"
#include "privops.h"
#include "sched.h"
#include "util.h"
/* ================================================== */
/* System clock drivers */
static lcl_ReadFrequencyDriver drv_read_freq;
static lcl_SetFrequencyDriver drv_set_freq;
static lcl_SetSyncStatusDriver drv_set_sync_status;
static lcl_AccrueOffsetDriver drv_accrue_offset;
static lcl_OffsetCorrectionDriver drv_get_offset_correction;
/* Current frequency as requested by the local module (in ppm) */
static double base_freq;
/* Maximum frequency that can be set by drv_set_freq (in ppm) */
static double max_freq;
/* Maximum expected delay in the actual frequency change (e.g. kernel ticks)
in local time */
static double max_freq_change_delay;
/* Maximum allowed frequency offset relative to the base frequency */
static double max_corr_freq;
/* Amount of outstanding offset to process */
static double offset_register;
/* Minimum offset to correct */
#define MIN_OFFSET_CORRECTION 1.0e-9
/* Current frequency offset between base_freq and the real clock frequency
as set by drv_set_freq (not in ppm) */
static double slew_freq;
/* Time (raw) of last update of slewing frequency and offset */
static struct timespec slew_start;
/* Limits for the slew timeout */
#define MIN_SLEW_TIMEOUT 1.0
#define MAX_SLEW_TIMEOUT 1.0e4
/* Scheduler timeout ID for ending of the currently running slew */
static SCH_TimeoutID slew_timeout_id;
/* Suggested offset correction rate (correction time * offset) */
static double correction_rate;
/* Maximum expected offset correction error caused by delayed change in the
real frequency of the clock */
static double slew_error;
/* Minimum offset that the system driver can slew faster than the maximum
frequency offset that it allows to be set directly */
static double fastslew_min_offset;
/* Maximum slew rate of the system driver */
static double fastslew_max_rate;
/* Flag indicating that the system driver is currently slewing */
static int fastslew_active;
/* ================================================== */
static void handle_end_of_slew(void *anything);
static void update_slew(void);
/* ================================================== */
/* Adjust slew_start on clock step */
static void
handle_step(struct timespec *raw, struct timespec *cooked, double dfreq,
double doffset, LCL_ChangeType change_type, void *anything)
{
if (change_type == LCL_ChangeUnknownStep) {
/* Reset offset and slewing */
slew_start = *raw;
offset_register = 0.0;
update_slew();
} else if (change_type == LCL_ChangeStep) {
UTI_AddDoubleToTimespec(&slew_start, -doffset, &slew_start);
}
}
/* ================================================== */
static void
start_fastslew(void)
{
if (!drv_accrue_offset)
return;
drv_accrue_offset(offset_register, 0.0);
DEBUG_LOG("fastslew offset=%e", offset_register);
offset_register = 0.0;
fastslew_active = 1;
}
/* ================================================== */
static void
stop_fastslew(struct timespec *now)
{
double corr;
if (!drv_get_offset_correction || !fastslew_active)
return;
/* Cancel the remaining offset */
drv_get_offset_correction(now, &corr, NULL);
drv_accrue_offset(corr, 0.0);
offset_register -= corr;
}
/* ================================================== */
static double
clamp_freq(double freq)
{
if (freq > max_freq)
return max_freq;
if (freq < -max_freq)
return -max_freq;
return freq;
}
/* ================================================== */
/* End currently running slew and start a new one */
static void
update_slew(void)
{
struct timespec now, end_of_slew;
double old_slew_freq, total_freq, corr_freq, duration;
/* Remove currently running timeout */
SCH_RemoveTimeout(slew_timeout_id);
LCL_ReadRawTime(&now);
/* Adjust the offset register by achieved slew */
duration = UTI_DiffTimespecsToDouble(&now, &slew_start);
offset_register -= slew_freq * duration;
stop_fastslew(&now);
/* Estimate how long should the next slew take */
if (fabs(offset_register) < MIN_OFFSET_CORRECTION) {
duration = MAX_SLEW_TIMEOUT;
} else {
duration = correction_rate / fabs(offset_register);
if (duration < MIN_SLEW_TIMEOUT)
duration = MIN_SLEW_TIMEOUT;
}
/* Get frequency offset needed to slew the offset in the duration
and clamp it to the allowed maximum */
corr_freq = offset_register / duration;
if (corr_freq < -max_corr_freq)
corr_freq = -max_corr_freq;
else if (corr_freq > max_corr_freq)
corr_freq = max_corr_freq;
/* Let the system driver perform the slew if the requested frequency
offset is too large for the frequency driver */
if (drv_accrue_offset && fabs(corr_freq) >= fastslew_max_rate &&
fabs(offset_register) > fastslew_min_offset) {
start_fastslew();
corr_freq = 0.0;
}
/* Get the new real frequency and clamp it */
total_freq = clamp_freq(base_freq + corr_freq * (1.0e6 - base_freq));
/* Set the new frequency (the actual frequency returned by the call may be
slightly different from the requested frequency due to rounding) */
total_freq = (*drv_set_freq)(total_freq);
/* Compute the new slewing frequency, it's relative to the real frequency to
make the calculation in offset_convert() cheaper */
old_slew_freq = slew_freq;
slew_freq = (total_freq - base_freq) / (1.0e6 - total_freq);
/* Compute the dispersion introduced by changing frequency and add it
to all statistics held at higher levels in the system */
slew_error = fabs((old_slew_freq - slew_freq) * max_freq_change_delay);
if (slew_error >= MIN_OFFSET_CORRECTION)
lcl_InvokeDispersionNotifyHandlers(slew_error);
/* Compute the duration of the slew and clamp it. If the slewing frequency
is zero or has wrong sign (e.g. due to rounding in the frequency driver or
when base_freq is larger than max_freq, or fast slew is active), use the
maximum timeout and try again on the next update. */
if (fabs(offset_register) < MIN_OFFSET_CORRECTION ||
offset_register * slew_freq <= 0.0) {
duration = MAX_SLEW_TIMEOUT;
} else {
duration = offset_register / slew_freq;
if (duration < MIN_SLEW_TIMEOUT)
duration = MIN_SLEW_TIMEOUT;
else if (duration > MAX_SLEW_TIMEOUT)
duration = MAX_SLEW_TIMEOUT;
}
/* Restart timer for the next update */
UTI_AddDoubleToTimespec(&now, duration, &end_of_slew);
slew_timeout_id = SCH_AddTimeout(&end_of_slew, handle_end_of_slew, NULL);
slew_start = now;
DEBUG_LOG("slew offset=%e corr_rate=%e base_freq=%f total_freq=%f slew_freq=%e duration=%f slew_error=%e",
offset_register, correction_rate, base_freq, total_freq, slew_freq,
duration, slew_error);
}
/* ================================================== */
static void
handle_end_of_slew(void *anything)
{
slew_timeout_id = 0;
update_slew();
}
/* ================================================== */
static double
read_frequency(void)
{
return base_freq;
}
/* ================================================== */
static double
set_frequency(double freq_ppm)
{
base_freq = freq_ppm;
update_slew();
return base_freq;
}
/* ================================================== */
static void
accrue_offset(double offset, double corr_rate)
{
offset_register += offset;
correction_rate = corr_rate;
update_slew();
}
/* ================================================== */
/* Determine the correction to generate the cooked time for given raw time */
static void
offset_convert(struct timespec *raw,
double *corr, double *err)
{
double duration, fastslew_corr, fastslew_err;
duration = UTI_DiffTimespecsToDouble(raw, &slew_start);
if (drv_get_offset_correction && fastslew_active) {
drv_get_offset_correction(raw, &fastslew_corr, &fastslew_err);
if (fastslew_corr == 0.0 && fastslew_err == 0.0)
fastslew_active = 0;
} else {
fastslew_corr = fastslew_err = 0.0;
}
*corr = slew_freq * duration + fastslew_corr - offset_register;
if (err) {
*err = fastslew_err;
if (fabs(duration) <= max_freq_change_delay)
*err += slew_error;
}
}
/* ================================================== */
/* Positive means currently fast of true time, i.e. jump backwards */
static int
apply_step_offset(double offset)
{
struct timespec old_time, new_time;
struct timeval new_time_tv;
double err;
LCL_ReadRawTime(&old_time);
UTI_AddDoubleToTimespec(&old_time, -offset, &new_time);
UTI_TimespecToTimeval(&new_time, &new_time_tv);
if (PRV_SetTime(&new_time_tv, NULL) < 0) {
DEBUG_LOG("settimeofday() failed");
return 0;
}
LCL_ReadRawTime(&old_time);
err = UTI_DiffTimespecsToDouble(&old_time, &new_time);
lcl_InvokeDispersionNotifyHandlers(fabs(err));
return 1;
}
/* ================================================== */
static void
set_sync_status(int synchronised, double est_error, double max_error)
{
double offset;
offset = fabs(offset_register);
if (est_error < offset)
est_error = offset;
max_error += offset;
if (drv_set_sync_status)
drv_set_sync_status(synchronised, est_error, max_error);
}
/* ================================================== */
void
SYS_Generic_CompleteFreqDriver(double max_set_freq_ppm, double max_set_freq_delay,
lcl_ReadFrequencyDriver sys_read_freq,
lcl_SetFrequencyDriver sys_set_freq,
lcl_ApplyStepOffsetDriver sys_apply_step_offset,
double min_fastslew_offset, double max_fastslew_rate,
lcl_AccrueOffsetDriver sys_accrue_offset,
lcl_OffsetCorrectionDriver sys_get_offset_correction,
lcl_SetLeapDriver sys_set_leap,
lcl_SetSyncStatusDriver sys_set_sync_status)
{
max_freq = max_set_freq_ppm;
max_freq_change_delay = max_set_freq_delay * (1.0 + max_freq / 1.0e6);
drv_read_freq = sys_read_freq;
drv_set_freq = sys_set_freq;
drv_accrue_offset = sys_accrue_offset;
drv_get_offset_correction = sys_get_offset_correction;
drv_set_sync_status = sys_set_sync_status;
base_freq = (*drv_read_freq)();
slew_freq = 0.0;
offset_register = 0.0;
max_corr_freq = CNF_GetMaxSlewRate() / 1.0e6;
fastslew_min_offset = min_fastslew_offset;
fastslew_max_rate = max_fastslew_rate / 1.0e6;
fastslew_active = 0;
lcl_RegisterSystemDrivers(read_frequency, set_frequency,
accrue_offset, sys_apply_step_offset ?
sys_apply_step_offset : apply_step_offset,
offset_convert, sys_set_leap, set_sync_status);
LCL_AddParameterChangeHandler(handle_step, NULL);
}
/* ================================================== */
void
SYS_Generic_Finalise(void)
{
struct timespec now;
/* Must *NOT* leave a slew running - clock could drift way off
if the daemon is not restarted */
SCH_RemoveTimeout(slew_timeout_id);
slew_timeout_id = 0;
(*drv_set_freq)(clamp_freq(base_freq));
LCL_ReadRawTime(&now);
stop_fastslew(&now);
}
/* ================================================== */