linuxptp/phc2sys.c

363 lines
8.5 KiB
C
Raw Normal View History

/**
* @file phc2sys.c
* @brief Utility program to synchronize two clocks via a PPS.
* @note Copyright (C) 2012 Richard Cochran <richardcochran@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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.
*/
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#include <linux/pps.h>
#include <linux/ptp_clock.h>
#include "missing.h"
#include "sk.h"
#include "sysoff.h"
#define KP 0.7
#define KI 0.3
#define NS_PER_SEC 1000000000LL
#define max_ppb 512000
#define min_ppb -512000
static clockid_t clock_open(char *device)
{
int fd;
if (device[0] != '/') {
if (!strcasecmp(device, "CLOCK_REALTIME"))
return CLOCK_REALTIME;
fprintf(stderr, "unknown clock %s\n", device);
return CLOCK_INVALID;
}
fd = open(device, O_RDWR);
if (fd < 0) {
fprintf(stderr, "cannot open %s: %m\n", device);
return CLOCK_INVALID;
}
return FD_TO_CLOCKID(fd);
}
static void clock_ppb(clockid_t clkid, double ppb)
{
struct timex tx;
memset(&tx, 0, sizeof(tx));
tx.modes = ADJ_FREQUENCY;
tx.freq = (long) (ppb * 65.536);
if (clock_adjtime(clkid, &tx) < 0)
fprintf(stderr, "failed to adjust the clock: %m\n");
}
static void clock_step(clockid_t clkid, int64_t ns)
{
struct timex tx;
int sign = 1;
if (ns < 0) {
sign = -1;
ns *= -1;
}
memset(&tx, 0, sizeof(tx));
tx.modes = ADJ_SETOFFSET | ADJ_NANO;
tx.time.tv_sec = sign * (ns / NS_PER_SEC);
tx.time.tv_usec = sign * (ns % NS_PER_SEC);
/*
* The value of a timeval is the sum of its fields, but the
* field tv_usec must always be non-negative.
*/
if (tx.time.tv_usec < 0) {
tx.time.tv_sec -= 1;
tx.time.tv_usec += 1000000000;
}
if (clock_adjtime(clkid, &tx) < 0)
fprintf(stderr, "failed to step clock: %m\n");
}
static int read_phc(clockid_t clkid, clockid_t sysclk, int readings,
int64_t *offset, uint64_t *ts)
{
struct timespec tdst1, tdst2, tsrc;
int i;
int64_t interval, best_interval = INT64_MAX;
/* Pick the quickest clkid reading. */
for (i = 0; i < readings; i++) {
if (clock_gettime(sysclk, &tdst1) ||
clock_gettime(clkid, &tsrc) ||
clock_gettime(sysclk, &tdst2)) {
perror("clock_gettime");
return 0;
}
interval = (tdst2.tv_sec - tdst1.tv_sec) * NS_PER_SEC +
tdst2.tv_nsec - tdst1.tv_nsec;
if (best_interval > interval) {
best_interval = interval;
*offset = (tdst1.tv_sec - tsrc.tv_sec) * NS_PER_SEC +
tdst1.tv_nsec - tsrc.tv_nsec + interval / 2;
*ts = tdst2.tv_sec * NS_PER_SEC + tdst2.tv_nsec;
}
}
return 1;
}
struct servo {
2012-08-31 01:44:37 +08:00
uint64_t saved_ts;
int64_t saved_offset;
double drift;
enum {
SAMPLE_0, SAMPLE_1, SAMPLE_2, SAMPLE_3, SAMPLE_N
} state;
};
static struct servo servo;
static void show_servo(FILE *fp, const char *label, int64_t offset, uint64_t ts)
{
fprintf(fp, "%s %9lld s%d %lld.%09llu drift %.2f\n", label, offset,
servo.state, ts / NS_PER_SEC, ts % NS_PER_SEC, servo.drift);
fflush(fp);
}
static void do_servo(struct servo *srv, clockid_t dst,
int64_t offset, uint64_t ts, double kp, double ki)
{
double ki_term, ppb;
switch (srv->state) {
case SAMPLE_0:
clock_ppb(dst, 0.0);
2012-08-31 01:44:37 +08:00
srv->saved_offset = offset;
srv->saved_ts = ts;
srv->state = SAMPLE_1;
break;
case SAMPLE_1:
srv->state = SAMPLE_2;
break;
case SAMPLE_2:
srv->state = SAMPLE_3;
break;
case SAMPLE_3:
2012-08-31 01:44:37 +08:00
srv->drift = (offset - srv->saved_offset) * 1e9 /
(ts - srv->saved_ts);
clock_ppb(dst, -srv->drift);
clock_step(dst, -offset);
srv->state = SAMPLE_N;
break;
case SAMPLE_N:
ki_term = ki * offset;
ppb = kp * offset + srv->drift + ki_term;
if (ppb < min_ppb) {
ppb = min_ppb;
} else if (ppb > max_ppb) {
ppb = max_ppb;
} else {
srv->drift += ki_term;
}
clock_ppb(dst, -ppb);
break;
}
}
static int read_pps(int fd, int64_t *offset, uint64_t *ts)
{
struct pps_fdata pfd;
pfd.timeout.sec = 10;
pfd.timeout.nsec = 0;
pfd.timeout.flags = ~PPS_TIME_INVALID;
if (ioctl(fd, PPS_FETCH, &pfd)) {
perror("ioctl PPS_FETCH");
return 0;
}
*ts = pfd.info.assert_tu.sec * NS_PER_SEC;
*ts += pfd.info.assert_tu.nsec;
*offset = *ts % NS_PER_SEC;
if (*offset > NS_PER_SEC / 2)
*offset -= NS_PER_SEC;
return 1;
}
static int do_pps_loop(char *pps_device, double kp, double ki, clockid_t dst)
{
int64_t pps_offset;
uint64_t pps_ts;
int fd;
fd = open(pps_device, O_RDONLY);
if (fd < 0) {
fprintf(stderr, "cannot open '%s': %m\n", pps_device);
return -1;
}
while (1) {
if (!read_pps(fd, &pps_offset, &pps_ts)) {
continue;
}
do_servo(&servo, dst, pps_offset, pps_ts, kp, ki);
show_servo(stdout, "pps", pps_offset, pps_ts);
}
close(fd);
return 0;
}
static int do_sysoff_loop(clockid_t src, clockid_t dst,
int rate, int n_readings, int sync_offset,
double kp, double ki)
{
uint64_t ts;
int64_t offset;
int err = 0, fd = CLOCKID_TO_FD(src);
while (1) {
usleep(1000000 / rate);
if (sysoff_measure(fd, n_readings, &offset, &ts)) {
err = -1;
break;
}
offset -= sync_offset * NS_PER_SEC;
do_servo(&servo, dst, offset, ts, kp, ki);
show_servo(stdout, "sys", offset, ts);
}
return err;
}
static void usage(char *progname)
{
fprintf(stderr,
"\n"
"usage: %s [options]\n\n"
" -c [dev|name] slave clock (CLOCK_REALTIME)\n"
" -d [dev] master PPS device\n"
" -s [dev|name] master clock\n"
" -i [iface] master clock by network interface\n"
" -P [kp] proportional constant (0.7)\n"
" -I [ki] integration constant (0.3)\n"
" -R [rate] slave clock update rate in HZ (1)\n"
" -N [num] number of master clock readings per update (5)\n"
" -O [offset] slave-master time offset (0)\n"
" -h prints this message and exits\n"
"\n",
progname);
}
int main(int argc, char *argv[])
{
double kp = KP, ki = KI;
char *device = NULL, *progname, *ethdev = NULL;
clockid_t src = CLOCK_INVALID, dst = CLOCK_REALTIME;
uint64_t phc_ts;
int64_t phc_offset;
int c, phc_readings = 5, phc_rate = 1, sync_offset = 0;
/* Process the command line arguments. */
progname = strrchr(argv[0], '/');
progname = progname ? 1+progname : argv[0];
while (EOF != (c = getopt(argc, argv, "c:d:hs:P:I:R:N:O:i:"))) {
switch (c) {
case 'c':
dst = clock_open(optarg);
break;
case 'd':
device = optarg;
break;
case 's':
src = clock_open(optarg);
break;
case 'P':
kp = atof(optarg);
break;
case 'I':
ki = atof(optarg);
break;
case 'R':
phc_rate = atoi(optarg);
break;
case 'N':
phc_readings = atoi(optarg);
break;
case 'O':
sync_offset = atoi(optarg);
break;
case 'i':
ethdev = optarg;
break;
case 'h':
usage(progname);
return 0;
default:
usage(progname);
return -1;
}
}
if (src == CLOCK_INVALID && ethdev) {
struct sk_ts_info ts_info;
char phc_device[16];
if (sk_get_ts_info(ethdev, &ts_info) || !ts_info.valid) {
fprintf(stderr, "can't autodiscover PHC device\n");
return -1;
}
sprintf(phc_device, "/dev/ptp%d", ts_info.phc_index);
src = clock_open(phc_device);
}
if (!(device || src != CLOCK_INVALID) || dst == CLOCK_INVALID) {
usage(progname);
return -1;
}
if (src != CLOCK_INVALID) {
struct timespec now;
if (clock_gettime(src, &now))
perror("clock_gettime");
now.tv_sec += sync_offset;
if (clock_settime(dst, &now))
perror("clock_settime");
}
if (device)
return do_pps_loop(device, kp, ki, dst);
if (dst == CLOCK_REALTIME &&
SYSOFF_SUPPORTED == sysoff_probe(CLOCKID_TO_FD(src), phc_readings))
return do_sysoff_loop(src, dst, phc_rate,
phc_readings, sync_offset, kp, ki);
while (1) {
usleep(1000000 / phc_rate);
if (!read_phc(src, dst, phc_readings, &phc_offset, &phc_ts)) {
continue;
}
phc_offset -= sync_offset * NS_PER_SEC;
do_servo(&servo, dst, phc_offset, phc_ts, kp, ki);
show_servo(stdout, "phc", phc_offset, phc_ts);
}
return 0;
}