Add non-PPS mode to phc2sys.
As some PHC hardware/drivers don't provide PPS, it may be useful to keep the system clock synchronized to PHC via clock_gettime(). While the precision of the clock is only in microsecond range, the error seems to be quite stable. The -d parameter now can be omitted if -s is provided. Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>master
Richard Cochran
parent
afd2a50b5b
commit
998093b6f7
105
phc2sys.c
105
phc2sys.c
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@ -85,33 +85,36 @@ static void clock_step(clockid_t clkid, int64_t ns)
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fprintf(stderr, "failed to step clock: %m\n");
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}
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static int64_t read_phc(clockid_t clkid, clockid_t sysclk, int rdelay)
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static int read_phc(clockid_t clkid, clockid_t sysclk, int rdelay, int64_t *offset, uint64_t *ts)
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{
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int64_t offset = 0;
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struct timespec tsrc, tdst;
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if (clkid == CLOCK_INVALID) {
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return 0;
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}
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if (rdelay) {
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struct timespec tsrc, tdst;
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if (clock_gettime(clkid, &tsrc))
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if (clock_gettime(clkid, &tsrc)) {
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perror("clock_gettime");
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if (clock_gettime(sysclk, &tdst))
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perror("clock_gettime");
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offset = tdst.tv_sec * NS_PER_SEC - tsrc.tv_sec * NS_PER_SEC +
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tdst.tv_nsec - tsrc.tv_nsec - rdelay;
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return 0;
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}
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return offset;
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if (clock_gettime(sysclk, &tdst)) {
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perror("clock_gettime");
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return 0;
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}
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*offset = tdst.tv_sec * NS_PER_SEC - tsrc.tv_sec * NS_PER_SEC +
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tdst.tv_nsec - tsrc.tv_nsec - rdelay;
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*ts = tdst.tv_sec * NS_PER_SEC + tdst.tv_nsec;
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return 1;
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}
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struct servo {
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uint64_t last_ts;
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double drift;
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enum {
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PPS_0, PPS_1, PPS_2, PPS_3, PPS_N
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SAMPLE_0, SAMPLE_1, SAMPLE_2, SAMPLE_3, SAMPLE_N
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} state;
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};
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@ -119,42 +122,34 @@ static struct servo servo;
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static void do_servo(struct servo *srv,
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clockid_t src, clockid_t dst,
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uint64_t ts, double kp, double ki, int rdelay)
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int64_t offset, uint64_t ts, double kp, double ki)
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{
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double ki_term, ppb;
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int64_t delta, offset, phc;
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int64_t delta;
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offset = ts % NS_PER_SEC;
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if (offset > NS_PER_SEC / 2) {
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offset -= NS_PER_SEC;
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}
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phc = read_phc(src, dst, rdelay);
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printf("s%d %lld.%09llu offset %9lld phc %9lld drift %.2f\n",
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srv->state, ts / NS_PER_SEC, ts % NS_PER_SEC,
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offset, phc, srv->drift);
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printf("s%d %lld.%09llu drift %.2f\n",
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srv->state, ts / NS_PER_SEC, ts % NS_PER_SEC, srv->drift);
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switch (srv->state) {
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case PPS_0:
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case SAMPLE_0:
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clock_ppb(dst, 0.0);
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srv->state = PPS_1;
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srv->state = SAMPLE_1;
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break;
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case PPS_1:
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srv->state = PPS_2;
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case SAMPLE_1:
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srv->state = SAMPLE_2;
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break;
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case PPS_2:
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case SAMPLE_2:
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delta = ts - srv->last_ts;
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offset = delta - NS_PER_SEC;
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srv->drift = offset;
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clock_ppb(dst, -offset);
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srv->state = PPS_3;
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srv->state = SAMPLE_3;
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break;
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case PPS_3:
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case SAMPLE_3:
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clock_step(dst, -offset);
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srv->state = PPS_N;
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srv->state = SAMPLE_N;
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break;
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case PPS_N:
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case SAMPLE_N:
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ki_term = ki * offset;
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ppb = kp * offset + srv->drift + ki_term;
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if (ppb < min_ppb) {
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@ -171,10 +166,10 @@ static void do_servo(struct servo *srv,
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srv->last_ts = ts;
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}
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static uint64_t read_pps(int fd)
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static int read_pps(int fd, int64_t *offset, uint64_t *ts)
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{
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struct pps_fdata pfd;
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uint64_t ts;
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pfd.timeout.sec = 10;
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pfd.timeout.nsec = 0;
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pfd.timeout.flags = ~PPS_TIME_INVALID;
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@ -182,9 +177,15 @@ static uint64_t read_pps(int fd)
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perror("ioctl PPS_FETCH");
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return 0;
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}
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ts = pfd.info.assert_tu.sec * NS_PER_SEC;
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ts += pfd.info.assert_tu.nsec;
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return ts;
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*ts = pfd.info.assert_tu.sec * NS_PER_SEC;
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*ts += pfd.info.assert_tu.nsec;
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*offset = *ts % NS_PER_SEC;
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if (*offset > NS_PER_SEC / 2)
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*offset -= NS_PER_SEC;
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return 1;
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}
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static void usage(char *progname)
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@ -208,8 +209,9 @@ int main(int argc, char *argv[])
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double kp = KP, ki = KI;
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char *device = NULL, *progname;
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clockid_t src = CLOCK_INVALID, dst = CLOCK_REALTIME;
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uint64_t ts;
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int c, fd, rdelay = 0;
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uint64_t pps_ts, phc_ts;
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int64_t pps_offset, phc_offset;
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int c, fd = 0, rdelay = 0;
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/* Process the command line arguments. */
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progname = strrchr(argv[0], '/');
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@ -243,15 +245,17 @@ int main(int argc, char *argv[])
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}
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}
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if (!device || dst == CLOCK_INVALID) {
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if (!(device || src != CLOCK_INVALID) || dst == CLOCK_INVALID) {
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usage(progname);
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return -1;
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}
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if (device) {
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fd = open(device, O_RDONLY);
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if (fd < 0) {
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fprintf(stderr, "cannot open %s: %m\n", device);
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return -1;
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}
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}
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if (src != CLOCK_INVALID) {
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struct timespec now;
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if (clock_gettime(src, &now))
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@ -260,8 +264,21 @@ int main(int argc, char *argv[])
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perror("clock_settime");
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}
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while (1) {
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ts = read_pps(fd);
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do_servo(&servo, src, dst, ts, kp, ki, rdelay);
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if (fd > 0) {
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if (!read_pps(fd, &pps_offset, &pps_ts))
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continue;
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printf("pps %9lld ", pps_offset);
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} else
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usleep(1000000);
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if (!read_phc(src, dst, rdelay, &phc_offset, &phc_ts))
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continue;
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printf("phc %9lld ", phc_offset);
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if (fd > 0)
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do_servo(&servo, src, dst, pps_offset, pps_ts, kp, ki);
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else
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do_servo(&servo, src, dst, phc_offset, phc_ts, kp, ki);
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}
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return 0;
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}
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