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|
/*
* ntpshm.c - put time information in SHM segment for xntpd
* struct shmTime and getShmTime from file in the xntp distribution:
* sht.c - Testprogram for shared memory refclock
*
* This file is Copyright (c) 2010 by the GPSD project
* BSD terms apply: see the file COPYING in the distribution root for details.
*/
#include <string.h>
#include <libgen.h>
#include <stdbool.h>
#include <math.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <pthread.h>
#ifndef S_SPLINT_S
#include <sys/wait.h>
#include <sys/socket.h>
#include <unistd.h>
#endif /* S_SPLINT_S */
#include "gpsd.h"
#if defined(HAVE_SYS_TIMEPPS_H)
#include <fcntl.h> /* needed for open() and friends */
#endif
#ifdef NTPSHM_ENABLE
#include <sys/time.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#define PPS_MAX_OFFSET 100000 /* microseconds the PPS can 'pull' */
#define PUT_MAX_OFFSET 1000000 /* microseconds for lost lock */
#define NTPD_BASE 0x4e545030 /* "NTP0" */
#define SHM_UNIT 0 /* SHM driver unit number (0..3) */
struct shmTime
{
int mode; /* 0 - if valid set
* use values,
* clear valid
* 1 - if valid set
* if count before and after read of values is equal,
* use values
* clear valid
*/
int count;
time_t clockTimeStampSec;
int clockTimeStampUSec;
time_t receiveTimeStampSec;
int receiveTimeStampUSec;
int leap;
int precision;
int nsamples;
int valid;
int pad[10];
};
/* Note: you can start gpsd as non-root, and have it work with ntpd.
* However, it will then only use the ntpshm segments 2 and 3.
*
* Ntpd always runs as root (to be able to control the system clock).
* Its logics for the creation of ntpshm segments are:
*
* Segments 0 and 1: permissions 0600, i.e. other programs can only
* read and write as root.
*
* Segments 2 and 3: permissions 0666, i.e. other programs can read
* and write as any user. I.e.: if ntpd has been
* configured to use these segments, any
* unpriviliged user is allowed to provide data
* for synchronisation.
*
* As gpsd can be started as both root and non-root, this behaviour is
* mimiced by:
*
* Started as root: do as ntpd when attaching (creating) the segments.
* (In contrast to ntpd, which only attaches (creates) configured
* segments, gpsd creates all segments.)
*
* Started as non-root: only attach (create) segments 2 and 3 with
* permissions 0666. As the permissions are for any user, the creator
* does not matter.
*
* For each GPS module gpsd controls, it will use the attached ntpshm
* segments in pairs (for coarse clock and pps source, respectively)
* starting from the first found segments. I.e. started as root, one
* GPS will deliver data on segments 0 and 1, and as non-root data
* will be delivered on segments 2 and 3.
*
* to debug, try looking at the live segments this way
* ipcs -m
* results should look like this:
* ------ Shared Memory Segments --------
* key shmid owner perms bytes nattch status
* 0x4e545030 0 root 700 96 2
* 0x4e545031 32769 root 700 96 2
* 0x4e545032 163842 root 666 96 1
* 0x4e545033 196611 root 666 96 1
*
* For a bit more data try this:
* cat /proc/sysvipc/shm
*
* If gpsd can not open the segments be sure you are not running SELinux
* or apparmor.
*
* if you see the shared segments (keys 1314148400 -- 1314148403), and
* no gpsd or ntpd is running then try removing them like this:
*
* ipcrm -M 0x4e545030
* ipcrm -M 0x4e545031
* ipcrm -M 0x4e545032
* ipcrm -M 0x4e545033
*/
static /*@null@*/ volatile struct shmTime *getShmTime(int unit)
{
int shmid;
unsigned int perms;
volatile struct shmTime *p;
// set the SHM perms the way ntpd does
if (unit < 2) {
// we are root, be careful
perms = 0600;
} else {
// we are not root, try to work anyway
perms = 0666;
}
/*
* Note: this call requires root under BSD, and possibly on
* well-secured Linux systems. This is why ntpshm_init() has to be
* called before privilege-dropping.
*/
shmid = shmget((key_t) (NTPD_BASE + unit),
sizeof(struct shmTime), (int)(IPC_CREAT | perms));
if (shmid == -1) {
gpsd_report(LOG_ERROR, "NTPD shmget(%ld, %zd, %o) fail: %s\n",
(long int)(NTPD_BASE + unit), sizeof(struct shmTime),
(int)perms, strerror(errno));
return NULL;
}
p = (struct shmTime *)shmat(shmid, 0, 0);
/*@ -mustfreefresh */
if ((int)(long)p == -1) {
gpsd_report(LOG_ERROR, "NTPD shmat failed: %s\n",
strerror(errno));
return NULL;
}
gpsd_report(LOG_PROG, "NTPD shmat(%d,0,0) succeeded, segment %d\n",
shmid, unit);
return p;
/*@ +mustfreefresh */
}
void ntpshm_init(struct gps_context_t *context, bool enablepps)
/* Attach all NTP SHM segments. Called once at startup, while still root. */
{
int i;
for (i = 0; i < NTPSHMSEGS; i++) {
// Only grab the first two when running as root.
if (2 <= i || 0 == getuid()) {
context->shmTime[i] = getShmTime(i);
}
}
memset(context->shmTimeInuse, 0, sizeof(context->shmTimeInuse));
# ifdef PPS_ENABLE
context->shmTimePPS = enablepps;
# endif /* PPS_ENABLE */
context->enable_ntpshm = true;
}
static int ntpshm_alloc(struct gps_context_t *context)
/* allocate NTP SHM segment. return its segment number, or -1 */
{
int i;
for (i = 0; i < NTPSHMSEGS; i++)
if (context->shmTime[i] != NULL && !context->shmTimeInuse[i]) {
context->shmTimeInuse[i] = true;
memset((void *)context->shmTime[i], 0, sizeof(struct shmTime));
context->shmTime[i]->mode = 1;
context->shmTime[i]->leap = LEAP_NOTINSYNC;
context->shmTime[i]->precision = -1; /* initially 0.5 sec */
context->shmTime[i]->nsamples = 3; /* stages of median filter */
return i;
}
return -1;
}
static bool ntpshm_free(struct gps_context_t * context, int segment)
/* free NTP SHM segment */
{
if (segment < 0 || segment >= NTPSHMSEGS)
return false;
context->shmTimeInuse[segment] = false;
return true;
}
int ntpshm_put(struct gps_device_t *session, double fixtime, double fudge)
/* put a received fix time into shared memory for NTP */
{
/* shmTime is volatile to try to prevent C compiler from reordering
* writes, or optimizing some 'dead code'. but CPU cache may still
*write out of order since we do not use memory barriers, yet */
volatile struct shmTime *shmTime = NULL;
struct timeval tv;
double seconds, microseconds;
// gpsd_report(LOG_PROG, "NTP: doing ntpshm_put(,%g, %g)\n", fixtime, fudge);
if (session->shmindex < 0 ||
(shmTime = session->context->shmTime[session->shmindex]) == NULL) {
gpsd_report(LOG_RAW, "NTPD missing shm\n");
return 0;
}
(void)gettimeofday(&tv, NULL);
fixtime += fudge;
microseconds = 1000000.0 * modf(fixtime, &seconds);
if (shmTime->clockTimeStampSec == (time_t) seconds) {
gpsd_report(LOG_RAW, "NTPD ntpshm_put: skipping duplicate second\n");
return 0;
}
/* we use the shmTime mode 1 protocol
*
* ntpd does this:
*
* reads valid.
* IFF valid is 1
* reads count
* reads values
* reads count
* IFF count unchanged
* use values
* clear valid
*
*/
shmTime->valid = 0;
shmTime->count++;
/* FIXME need a memory barrier here to prevent write reordering by
* the compiler or CPU cache */
shmTime->clockTimeStampSec = (time_t) seconds;
shmTime->clockTimeStampUSec = (int)microseconds;
shmTime->receiveTimeStampSec = (time_t) tv.tv_sec;
shmTime->receiveTimeStampUSec = (int)tv.tv_usec;
shmTime->leap = session->context->leap_notify;
/* setting the precision here does not seem to help anything, too
* hard to calculate properly anyway. Let ntpd figure it out.
* Any NMEA will be about -1 or -2.
* Garmin GPS-18/USB is around -6 or -7.
*/
/* FIXME need a memory barrier here to prevent write reordering by
* the compiler or CPU cache */
shmTime->count++;
shmTime->valid = 1;
gpsd_report(LOG_RAW,
"NTPD ntpshm_put: Clock: %lu.%06lu @ %lu.%06lu, fudge: %0.3f\n",
(unsigned long)seconds, (unsigned long)microseconds,
(unsigned long)tv.tv_sec, (unsigned long)tv.tv_usec, fudge);
return 1;
}
#ifdef PPS_ENABLE
/*
* Possible pins for PPS: DCD, CTS, RTS, RI. Pinouts:
*
* DB9 DB25 Name Full name
* --- ---- ---- --------------------
* 3 2 TXD --> Transmit Data
* 2 3 RXD <-- Receive Data
* 7 4 RTS --> Request To Send
* 8 5 CTS <-- Clear To Send
* 6 6 DSR <-- Data Set Ready
* 4 20 DTR --> Data Terminal Ready
* 1 8 DCD <-- Data Carrier Detect
* 9 22 RI <-- Ring Indicator
* 5 7 SG Signal ground
*/
/*@unused@*//* splint is confused here */
/* put NTP shared memory info based on received PPS pulse
*
* good news is that kernel PPS gives us nSec resolution
* bad news is that ntpshm only has uSec resolution
*/
static int ntpshm_pps(struct gps_device_t *session, struct timeval *tv)
{
volatile struct shmTime *shmTime = NULL, *shmTimeP = NULL;
time_t seconds;
/* FIX-ME, microseconds needs to be set for 5Hz PPS */
int microseconds = 0;
int precision;
double offset;
long l_offset;
if (0 > session->shmindex || 0 > session->shmTimeP ||
(shmTime = session->context->shmTime[session->shmindex]) == NULL ||
(shmTimeP = session->context->shmTime[session->shmTimeP]) == NULL)
return 0;
/* PPS has no seconds attached to it.
* check to see if we have a fresh timestamp from the
* GPS serial input then use that */
/* FIX-ME, does not handle 5Hz yet */
#ifdef S_SPLINT_S /* avoids an internal error in splint 3.1.1 */
l_offset = 0;
#else
l_offset = tv->tv_sec - shmTime->receiveTimeStampSec;
#endif
/*@ -ignorequals @*/
l_offset *= 1000000;
l_offset += tv->tv_usec - shmTime->receiveTimeStampUSec;
if (0 > l_offset || 1000000 < l_offset) {
gpsd_report(LOG_RAW, "PPS ntpshm_pps: no current GPS seconds: %ld\n",
(long)l_offset);
return -1;
}
/*@+relaxtypes@*/
seconds = shmTime->clockTimeStampSec + 1;
offset = fabs((tv->tv_sec - seconds)
+ ((double)(tv->tv_usec - 0) / 1000000.0));
/*@-relaxtypes@*/
/* we use the shmTime mode 1 protocol
*
* ntpd does this:
*
* reads valid.
* IFF valid is 1
* reads count
* reads values
* reads count
* IFF count unchanged
* use values
* clear valid
*
*/
shmTimeP->valid = 0;
shmTimeP->count++;
shmTimeP->clockTimeStampSec = seconds;
shmTimeP->clockTimeStampUSec = (int)microseconds;
shmTimeP->receiveTimeStampSec = (time_t) tv->tv_sec;
shmTimeP->receiveTimeStampUSec = (int)tv->tv_usec;
shmTimeP->leap = session->context->leap_notify;
/* precision is a placebo, ntpd does not really use it
* real world accuracy is around 16uS, thus -16 precision */
shmTimeP->precision = -16;
shmTimeP->count++;
shmTimeP->valid = 1;
/* this is more an offset jitter/dispersion than precision,
* but still useful for debug */
precision = offset != 0 ? (int)(ceil(log(offset) / M_LN2)) : -20;
gpsd_report(LOG_RAW, "PPS ntpshm_pps %lu.%03lu @ %lu.%06lu, preci %d\n",
(unsigned long)seconds, (unsigned long)microseconds / 1000,
(unsigned long)tv->tv_sec, (unsigned long)tv->tv_usec,
precision);
return 1;
}
/*
* Warning: This is a potential portability problem.
* It's needed so that TIOCMIWAIT will be defined and the serial-PPS
* code will work, but it's not a SuS/POSIX standard header. We're
* going to include it unconditionally here because we expect both
* Linux and BSD to have it and we want compilation to break with
* an audible snapping sound.
*/
#include <sys/ioctl.h>
#ifndef S_SPLINT_S
#include <pthread.h> /* pacifies OpenBSD's compiler */
#endif
#if defined(HAVE_SYS_TIMEPPS_H)
/* use RFC 2783 PPS API */
/* this needs linux >= 2.6.34 and
* CONFIG_PPS=y
* CONFIG_PPS_DEBUG=y [optional to kernel log pulses]
* CONFIG_PPS_CLIENT_LDISC=y
*/
/* get timepps.h from the pps-tools package, or from here:
* http://www.mail-archive.com/debian-glibc@lists.debian.org/msg43125.html
* RFC2783 says timepps.h is in sys
*/
#include <sys/timepps.h>
#include <glob.h>
#endif
/* and for chrony */
#include <sys/un.h>
/* normalize a timespec */
#define TS_NORM(ts) \
do { \
if ( 1000000000 <= (ts)->tv_nsec ) { \
(ts)->tv_nsec -= 1000000000; \
(ts)->tv_sec++; \
} else if ( 0 > (ts)->tv_nsec ) { \
(ts)->tv_nsec += 1000000000; \
(ts)->tv_sec--; \
} \
} while (0)
/* normalize a timeval */
#define TV_NORM(tv) \
do { \
if ( 1000000 <= (tv)->tv_usec ) { \
(tv)->tv_usec -= 1000000; \
(tv)->tv_sec++; \
} else if ( 0 > (tv)->tv_usec ) { \
(tv)->tv_usec += 1000000; \
(tv)->tv_sec--; \
} \
} while (0)
/* convert timespec to timeval, with rounding */
#define TSTOTV(tv, ts) \
do { \
(tv)->tv_sec = (ts)->tv_sec; \
(tv)->tv_usec = ((ts)->tv_nsec + 500)/1000; \
TV_NORM( tv ); \
} while (0)
/* convert timeval to timespec */
#define TVTOTS(ts, tv) \
do { \
(ts)->tv_sec = (tv)->tv_sec; \
(ts)->tv_nsec = (tv)->tv_usec*1000; \
TS_NORM( ts ); \
} while (0)
#endif
#if defined(PPS_ENABLE) && defined(TIOCMIWAIT)
#if defined(HAVE_SYS_TIMEPPS_H)
/* return handle for kernel pps, or -1 */
static int init_kernel_pps(struct gps_device_t *session) {
int ldisc = 18; /* the PPS line discipline */
pps_params_t pp;
glob_t globbuf;
size_t i; /* to match type of globbuf.gl_pathc */
char pps_num = 0; /* /dev/pps[pps_num] is our device */
char path[GPS_PATH_MAX] = "";
session->kernelpps_handle = -1;
if ( !isatty(session->gpsdata.gps_fd) ) {
gpsd_report(LOG_INF, "KPPS gps_fd not a tty\n");
return -1;
}
/* Attach the line PPS discipline, so no need to ldattach */
/* This activates the magic /dev/pps0 device */
/* Note: this ioctl() requires root */
if ( 0 > ioctl(session->gpsdata.gps_fd, TIOCSETD, &ldisc)) {
gpsd_report(LOG_INF, "KPPS cannot set PPS line discipline: %s\n"
, strerror(errno));
return -1;
}
/* uh, oh, magic file names!, this is not how RFC2783 was designed */
/* need to look in /sys/devices/virtual/pps/pps?/path
* (/sys/class/pps/pps?/path is just a link to that)
* to find the /dev/pps? that matches our serial port.
* this code fails if there are more then 10 pps devices.
*
* yes, this could be done with libsysfs, but trying to keep the
* number of required libs small */
memset( (void *)&globbuf, 0, sizeof(globbuf));
glob("/sys/devices/virtual/pps/pps?/path", 0, NULL, &globbuf);
memset( (void *)&path, 0, sizeof(path));
for ( i = 0; i < globbuf.gl_pathc; i++ ) {
int fd = open(globbuf.gl_pathv[i], O_RDONLY);
if ( 0 <= fd ) {
ssize_t r = read( fd, path, sizeof(path) -1);
if ( 0 < r ) {
path[r - 1] = '\0'; /* remove trailing \x0a */
}
close(fd);
}
gpsd_report(LOG_INF, "KPPS checking %s, %s\n"
, globbuf.gl_pathv[i], path);
if ( 0 == strncmp( path, session->gpsdata.dev.path, sizeof(path))) {
/* this is the pps we are looking for */
/* FIXME, now build the proper pps device path */
pps_num = globbuf.gl_pathv[i][28];
break;
}
memset( (void *)&path, 0, sizeof(path));
}
/* done with blob, clear it */
globfree(&globbuf);
if ( 0 == pps_num ) {
gpsd_report(LOG_INF, "KPPS device not found.\n");
return -1;
}
/* contruct the magic device path */
(void)snprintf(path, sizeof(path), "/dev/pps%c", pps_num);
/* root privs are required for this device open */
int ret = open(path, O_RDWR);
if ( 0 > ret ) {
gpsd_report(LOG_INF, "KPPS cannot open %s: %s\n"
, path, strerror(errno));
return -1;
}
/* root privs are not required past this point */
if ( 0 > time_pps_create(ret, &session->kernelpps_handle )) {
gpsd_report(LOG_INF, "KPPS time_pps_create(%d) failed: %s\n"
, ret, strerror(errno));
return -1;
} else {
/* have kernel PPS handle */
int caps;
/* get features supported */
if ( 0 > time_pps_getcap(session->kernelpps_handle, &caps)) {
gpsd_report(LOG_ERROR, "KPPS time_pps_getcap() failed\n");
} else {
gpsd_report(LOG_INF, "KPPS caps %0x\n", caps);
}
/* linux 2.6.34 can not PPS_ECHOASSERT | PPS_ECHOCLEAR */
memset( (void *)&pp, 0, sizeof(pps_params_t));
pp.mode = PPS_CAPTUREBOTH;
if ( 0 > time_pps_setparams(session->kernelpps_handle, &pp)) {
gpsd_report(LOG_ERROR,
"KPPS time_pps_setparams() failed: %s\n", strerror(errno));
time_pps_destroy(session->kernelpps_handle);
return -1;
}
}
return 0;
}
#endif /* defined(HAVE_SYS_TIMEPPS_H) */
/*@-mustfreefresh -type@ -unrecog*/
static /*@null@*/ void *gpsd_ppsmonitor(void *arg)
{
struct gps_device_t *session = (struct gps_device_t *)arg;
int cycle, duration, state = 0, laststate = -1, unchanged = 0;
struct timeval tv;
struct timespec ts;
struct timeval pulse[2] = { {0, 0}, {0, 0} };
#if defined(HAVE_SYS_TIMEPPS_H)
int kpps_edge = 0; /* 0 = clear edge, 1 = assert edge */
int cycle_kpps, duration_kpps;
struct timespec pulse_kpps[2] = { {0, 0}, {0, 0} };
struct timespec tv_kpps;
pps_info_t pi;
#endif
/* for chrony SOCK interface, which allows nSec timekeeping */
#define SOCK_MAGIC 0x534f434b
struct sock_sample {
struct timeval tv;
double offset;
int pulse;
int leap;
int _pad; /* unused */
int magic; /* must be SOCK_MAGIC */
} sample;
/* chrony must be started first as chrony insists on creating the socket */
/* open the chrony socket */
int chronyfd = -1;
char chrony_path[PATH_MAX];
gpsd_report(LOG_PROG, "PPS Create Thread gpsd_ppsmonitor\n");
if ( 0 == getuid() ) {
/* this case will fire on command-line devices;
* they're opened before priv-dropping. Matters because
* only root can use /var/run.
*/
(void)snprintf(chrony_path, sizeof (chrony_path),
"/var/run/chrony.%s.sock", basename(session->gpsdata.dev.path));
} else {
(void)snprintf(chrony_path, sizeof (chrony_path),
"/tmp/chrony.%s.sock", basename(session->gpsdata.dev.path));
}
if (access(chrony_path, F_OK) != 0) {
gpsd_report(LOG_PROG, "PPS chrony socket %s doesn't exist\n", chrony_path);
} else {
chronyfd = netlib_localsocket(chrony_path, SOCK_DGRAM);
if (chronyfd < 0)
gpsd_report(LOG_PROG, "PPS can not connect chrony socket: %s\n",
chrony_path);
else
gpsd_report(LOG_RAW, "PPS using chrony socket: %s\n", chrony_path);
}
/* end chrony */
/* wait for the device to go active - makes this safe to call early */
while (session->gpsdata.gps_fd == -1) {
/* should probably remove this once code is verified */
gpsd_report(LOG_PROG, "PPS thread awaiting device activation\n");
(void)sleep(1);
}
#if defined(HAVE_SYS_TIMEPPS_H)
/* some operations in init_kernel_pps() require root privs */
(void)init_kernel_pps( session );
if ( 0 <= session->kernelpps_handle ) {
gpsd_report(LOG_WARN, "KPPS kernel PPS will be used\n");
}
memset( (void *)&pi, 0, sizeof(pps_info_t));
#endif
/* root privileges are not required after this point */
#define PPS_LINE_TIOC (TIOCM_CD|TIOCM_CAR|TIOCM_RI|TIOCM_CTS)
/*
* Wait for status change on any handshake line. The only assumption here
* is that no GPS lights up more than one of these pins. By waiting on
* all of them we remove a configuration switch.
*/
for (;;) {
int ok = 0;
char *log = NULL;
char *log1 = NULL;
if (ioctl(session->gpsdata.gps_fd, TIOCMIWAIT, PPS_LINE_TIOC) != 0) {
gpsd_report(LOG_ERROR, "PPS ioctl(TIOCMIWAIT) failed: %d %.40s\n"
, errno, strerror(errno));
break;
}
/*@-noeffect@*/
#ifdef HAVE_CLOCK_GETTIME
/* using clock_gettime() here, that is nSec,
* not uSec like gettimeofday */
if ( 0 > clock_gettime(CLOCK_REALTIME, &ts) ) {
/* uh, oh, can not get time! */
gpsd_report(LOG_ERROR, "PPS clock_gettime() failed\n");
break;
}
TSTOTV( &tv, &ts);
#else
if ( 0 > gettimeofday(&tv, NULL) ) {
/* uh, oh, can not get time! */
gpsd_report(LOG_ERROR, "PPS gettimeofday() failed\n");
break;
}
TVTOTS( &ts, &tv);
#endif
/*@+noeffect@*/
#if defined(HAVE_SYS_TIMEPPS_H)
if ( 0 <= session->kernelpps_handle ) {
struct timespec kernelpps_tv;
/* on a quad core 2.4GHz Xeon this removes about 20uS of
* latency, and about +/-5uS of jitter over the other method */
memset( (void *)&kernelpps_tv, 0, sizeof(kernelpps_tv));
if ( 0 > time_pps_fetch(session->kernelpps_handle, PPS_TSFMT_TSPEC
, &pi, &kernelpps_tv)) {
gpsd_report(LOG_ERROR, "KPPS kernel PPS failed\n");
} else {
// find the last edge
if ( pi.assert_timestamp.tv_sec > pi.clear_timestamp.tv_sec ) {
kpps_edge = 1;
tv_kpps = pi.assert_timestamp;
} else if ( pi.assert_timestamp.tv_sec < pi.clear_timestamp.tv_sec ) {
kpps_edge = 0;
tv_kpps = pi.clear_timestamp;
} else if ( pi.assert_timestamp.tv_nsec > pi.clear_timestamp.tv_nsec ) {
kpps_edge = 1;
tv_kpps = pi.assert_timestamp;
} else {
kpps_edge = 0;
tv_kpps = pi.clear_timestamp;
}
gpsd_report(LOG_PROG, "KPPS assert %ld.%09ld, sequence: %ld - "
"clear %ld.%09ld, sequence: %ld\n",
pi.assert_timestamp.tv_sec,
pi.assert_timestamp.tv_nsec,
pi.assert_sequence,
pi.clear_timestamp.tv_sec,
pi.clear_timestamp.tv_nsec,
pi.clear_sequence);
gpsd_report(LOG_PROG, "KPPS data: using %s\n",
kpps_edge ? "assert" : "clear");
#define timediff_kpps(x, y) (int)((x.tv_sec-y.tv_sec)*1000000+((x.tv_nsec-y.tv_nsec)/1000))
cycle_kpps = timediff_kpps(tv_kpps, pulse_kpps[kpps_edge]);
duration_kpps = timediff_kpps(tv_kpps, pulse_kpps[(int)(kpps_edge == 0)]);
if ( 3000000 < duration_kpps ) {
// invisible pulse
duration_kpps = 0;
}
#undef timediff_kpps
gpsd_report(LOG_INF,
"KPPS cycle: %7d, duration: %7d @ %lu.%09lu\n",
cycle_kpps, duration_kpps,
(unsigned long)tv_kpps.tv_sec,
(unsigned long)tv_kpps.tv_nsec);
pulse_kpps[kpps_edge] = tv_kpps;
}
}
#endif
ok = 0;
log = NULL;
/*@ +ignoresigns */
if (ioctl(session->gpsdata.gps_fd, TIOCMGET, &state) != 0) {
gpsd_report(LOG_ERROR, "PPS ioctl(TIOCMGET) failed\n");
break;
}
/*@ -ignoresigns */
state = (int)((state & PPS_LINE_TIOC) != 0);
/*@ +boolint @*/
#define timediff(x, y) (int)((x.tv_sec-y.tv_sec)*1000000+x.tv_usec-y.tv_usec)
cycle = timediff(tv, pulse[state]);
duration = timediff(tv, pulse[(int)(state == 0)]);
#undef timediff
/*@ -boolint @*/
if (state == laststate) {
/* some pulses may be so short that state never changes */
if (999000 < cycle && 1001000 > cycle) {
duration = 0;
unchanged = 0;
gpsd_report(LOG_RAW,
"PPS pps-detect on %s invisible pulse\n",
session->gpsdata.dev.path);
} else if (++unchanged == 10) {
unchanged = 1;
gpsd_report(LOG_WARN,
"PPS TIOCMIWAIT returns unchanged state, ppsmonitor sleeps 10\n");
(void)sleep(10);
}
} else {
gpsd_report(LOG_RAW, "PPS pps-detect on %s changed to %d\n",
session->gpsdata.dev.path, state);
laststate = state;
unchanged = 0;
}
pulse[state] = tv;
if (unchanged) {
// strange, try again
continue;
}
gpsd_report(LOG_INF, "PPS cycle: %7d, duration: %7d @ %lu.%06lu\n",
cycle, duration,
(unsigned long)tv.tv_sec, (unsigned long)tv.tv_usec);
/* only listen to PPS after 4 consecutive fixes, otherwise time
* will be inaccurate.
* Not sure yet how to handle uBlox UBX_MODE_TMONLY
* Do not use ship_to_ntp here since it is synced to packets
* and this thread is asynchonous to packets */
if ( 3 < session->fixcnt ) {
/*
* The PPS pulse is normally a short pulse with a frequency of
* 1 Hz, and the UTC second is defined by the front edge. But we
* don't know the polarity of the pulse (different receivers
* emit different polarities). The duration variable is used to
* determine which way the pulse is going. The code assumes
* that the UTC second is changing when the signal has not
* been changing for at least 800ms, i.e. it assumes the duty
* cycle is at most 20%.
*
* Some GPSes instead output a square wave that is 0.5 Hz and each
* edge denotes the start of a second.
*
* Some GPSes, like the Globalsat MR-350P, output a 1uS pulse.
* The pulse is so short that TIOCMIWAIT sees a state change
* but by the time TIOCMGET is called the pulse is gone.
*
* A few stupid GPSes, like the Furuno GPSClock, output a 1.0 Hz
* square wave where the leading edge is the start of a second
*
* 5Hz GPS (Garmin 18-5Hz) pulses at 5Hz. Set the pulse length to
* 40ms which gives a 160ms pulse before going high.
*
*/
log = "Unknown error";
if (199000 > cycle) {
// too short to even be a 5Hz pulse
log = "Too short for 5Hz\n";
} else if (201000 > cycle) {
/* 5Hz cycle */
/* looks like 5hz PPS pulse */
if (100000 > duration) {
/* BUG: how does the code know to tell ntpd
* which 1/5 of a second to use?? */
ok = 1;
log = "5Hz PPS pulse\n";
}
} else if (999000 > cycle) {
log = "Too long for 5Hz, too short for 1Hz\n";
} else if (1001000 > cycle) {
/* looks like PPS pulse or square wave */
if (0 == duration) {
ok = 1;
log = "invisible pulse\n";
} else if (499000 > duration) {
/* end of the short "half" of the cycle */
/* aka the trailing edge */
log = "1Hz trailing edge\n";
} else if (501000 > duration) {
/* looks like 1.0 Hz square wave, ignore trailing edge */
if (state == 1) {
ok = 1;
log = "square\n";
}
} else {
/* end of the long "half" of the cycle */
/* aka the leading edge */
ok = 1;
log = "1Hz leading edge\n";
}
} else if (1999000 > cycle) {
log = "Too long for 1Hz, too short for 2Hz\n";
} else if (2001000 > cycle) {
/* looks like 0.5 Hz square wave */
if (999000 > duration) {
log = "0.5 Hz square too short duration\n";
} else if (1001000 > duration) {
ok = 1;
log = "0.5 Hz square wave\n";
} else {
log = "0.5 Hz square too long duration\n";
}
} else {
log = "Too long for 0.5Hz\n";
}
} else {
/* not a good fix, but a test for an otherwise good PPS
* would go here */
log = "no fix.\n";
}
/*@ -boolint @*/
if (0 != ok) {
gpsd_report(LOG_RAW, "PPS edge accepted %.100s", log);
/* chrony expects tv-sec since Jan 1970 */
/* FIXME!! offset is double of the error from local time */
sample.pulse = 0;
sample.leap = session->context->leap_notify;
sample.magic = SOCK_MAGIC;
#if defined(HAVE_SYS_TIMEPPS_H)
if ( 0 <= session->kernelpps_handle) {
/* pick the right edge */
if ( kpps_edge ) {
ts = pi.assert_timestamp; /* structure copy */
} else {
ts = pi.clear_timestamp; /* structure copy */
}
TSTOTV( &sample.tv, &ts);
} else
#endif
{
sample.tv = tv; /* structure copy */
}
/* FIXME!! this is wrong if signal is 5Hz or 10Hz instead of PPS */
/* careful, Unix time to nSec is more precision than a double */
sample.offset = 1 + session->last_fixtime - ts.tv_sec;
sample.offset -= ts.tv_nsec / 1e9;
/* was: defined(ONCORE_ENABLE) && defined(BINARY_ENABLE) */
#ifdef __UNUSED__
/*@-noeffect@*/
if (session->device_type == &oncore_binary) {
int pulse_delay_ns = session->driver.oncore.pps_offset_ns;
sample.offset += (double)pulse_delay_ns / 1000000000;
ts.tv_nsec -= pulse_delay_ns;
TS_NORM( &ts );
}
/*@+noeffect@*/
#endif
TSTOTV( &tv, &ts );
if (session->ship_to_ntpd) {
log1 = "accepted";
if ( 0 <= chronyfd ) {
log1 = "accepted chrony sock";
(void)send(chronyfd, &sample, sizeof (sample), 0);
}
(void)ntpshm_pps(session, &tv);
} else {
log1 = "skipped ship_to_ntp=0";
}
gpsd_report(LOG_RAW,
"PPS edge %.20s %lu.%06lu offset %.9f\n",
log1,
(unsigned long)sample.tv.tv_sec,
(unsigned long)sample.tv.tv_usec,
sample.offset);
if (session->context->pps_hook != NULL)
session->context->pps_hook(session, &tv);
} else {
gpsd_report(LOG_RAW, "PPS edge rejected %.100s", log);
}
}
gpsd_report(LOG_PROG, "PPS gpsd_ppsmonitor exited???\n");
/* pacify Coverity - falling through here is theoretically a handle leak */
if (chronyfd)
(void)close(chronyfd);
return NULL;
}
/*@+mustfreefresh +type +unrecog@*/
#endif /* PPS_ENABLE */
void ntpd_link_deactivate(struct gps_device_t *session)
/* release ntpshm storage for a session */
{
(void)ntpshm_free(session->context, session->shmindex);
session->shmindex = -1;
# ifdef PPS_ENABLE
(void)ntpshm_free(session->context, session->shmTimeP);
session->shmTimeP = -1;
#ifdef TIOCMIWAIT
pps_thread_deactivate(session);
#endif /* TIOCMIWAIT */
# endif /* PPS_ENABLE */
}
void ntpd_link_activate(struct gps_device_t *session)
/* set up ntpshm storage for a session - may fail if not called as root */
{
/* If we are talking to ntpd, allocate a shared-memory segment for "NMEA" time data */
if (session->context->enable_ntpshm)
session->shmindex = ntpshm_alloc(session->context);
if (0 > session->shmindex) {
gpsd_report(LOG_INF, "NTPD ntpshm_alloc() failed\n");
#if defined(PPS_ENABLE) && defined(TIOCMIWAIT)
} else if (session->context->shmTimePPS) {
/* We also have the 1pps capability, allocate a shared-memory segment
* for the 1pps time data and launch a thread to capture the 1pps
* transitions
*/
if ((session->shmTimeP = ntpshm_alloc(session->context)) < 0) {
gpsd_report(LOG_INF, "NTPD ntpshm_alloc(1) failed\n");
} else
pps_thread_activate(session);
#endif /* defined(PPS_ENABLE) && defined(TIOCMIWAIT) */
}
}
#if defined(PPS_ENABLE) && defined(TIOCMIWAIT)
void pps_thread_activate(struct gps_device_t *session)
/* activate a thread to watch the device's PPS transitions */
{
pthread_t pt;
if (session->shmTimeP >= 0) {
gpsd_report(LOG_PROG, "PPS thread launched\n");
/*@-compdef -nullpass@*/
(void)pthread_create(&pt, NULL, gpsd_ppsmonitor, (void *)session);
/*@+compdef +nullpass@*/
}
}
#else
void pps_thread_activate(struct gps_device_t *session UNUSED)
{
/* nothing to call */
}
#endif /* defined(PPS_ENABLE) && defined(TIOCMIWAIT) */
#if defined(PPS_ENABLE) && defined(HAVE_SYS_TIMEPPS_H)
void pps_thread_deactivate(struct gps_device_t *session)
/* cleanly terminate device's PPS thread */
{
if (session->kernelpps_handle > 0) {
gpsd_report(LOG_PROG, "PPS descriptor cleaned up\n");
time_pps_destroy(session->kernelpps_handle);
}
}
#else
void pps_thread_deactivate(struct gps_device_t *session UNUSED)
{
/* nothing to call */
}
#endif
#endif /* defined(PPS_ENABLE) && defined(HAVE_SYS_TIMEPPS_H) */
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