From 1d289787b64c41e189b92776e3b09506cc4cb406 Mon Sep 17 00:00:00 2001 From: Miroslav Lichvar Date: Wed, 14 Aug 2013 18:13:39 +0200 Subject: [PATCH] Add PHC refclock driver Implement a driver which allows using PTP hardware clock (PHC) as a reference clock. It uses the PTP_SYS_OFFSET ioctl or clock_gettime() to measure the offset between the PTP clock and the system clock. Ten readings are made for every driver poll and the fastest one is returned. As PHCs are typically kept in TAI instead of UTC, it's necessary to set the TAI/UTC offset manually by the offset option. This could be improved by obtaining the offset automatically from the right/UTC timezone. --- Makefile.in | 4 +- chrony.texi.in | 13 +++- configure | 14 ++++ refclock.c | 4 + refclock_phc.c | 195 +++++++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 227 insertions(+), 3 deletions(-) create mode 100644 refclock_phc.c diff --git a/Makefile.in b/Makefile.in index ecb036c..58af97b 100644 --- a/Makefile.in +++ b/Makefile.in @@ -44,8 +44,8 @@ OBJS = util.o sched.o regress.o local.o \ logging.o conf.o cmdmon.o keys.o \ nameserv.o acquire.o manual.o addrfilt.o \ cmdparse.o mkdirpp.o rtc.o pktlength.o clientlog.o \ - broadcast.o refclock.o refclock_shm.o refclock_sock.o \ - refclock_pps.o tempcomp.o $(HASH_OBJ) + broadcast.o refclock.o refclock_phc.o refclock_pps.o \ + refclock_shm.o refclock_sock.o tempcomp.o $(HASH_OBJ) EXTRA_OBJS=@EXTRA_OBJECTS@ diff --git a/chrony.texi.in b/chrony.texi.in index d7ff1ad..e455810 100644 --- a/chrony.texi.in +++ b/chrony.texi.in @@ -2462,7 +2462,7 @@ can function as a stratum 1 server. They are specified by the @code{refclock} directive. It has two mandatory parameters, a refclock driver name and a driver specific parameter. -There are currently three drivers included: +There are currently four drivers included: @table @code @item PPS @@ -2512,6 +2512,17 @@ protocol. The path where the socket should be created is described in the refclock SOCK /var/run/chrony.ttyS0.sock @end example +@item PHC +PTP hardware clock (PHC) driver. The parameter is the path to the device of +the PTP clock, which can be synchronised by a PTP daemon (e.g. @code{ptp4l} +from the @uref{http://linuxptp.sourceforge.net/, Linux PTP project}. The PTP +clocks are typically kept in TAI instead of UTC. The @code{offset} option can +be used to compensate for the current UTC/TAI offset. For example: + +@example +refclock PHC /dev/ptp0 poll 3 dpoll -2 offset -35 +@end example + @end table The @code{refclock} command also supports a number of subfields (which diff --git a/configure b/configure index 3c95598..e508f59 100755 --- a/configure +++ b/configure @@ -108,6 +108,7 @@ For better control, use the options below. --without-nss Don't use NSS even if it is available --without-tomcrypt Don't use libtomcrypt even if it is available --disable-ipv6 Disable IPv6 support + --disable-phc Disable PHC support --disable-pps Disable PPS API support --disable-rtc Don't include RTC even on Linux --disable-linuxcaps Disable Linux capabilities support @@ -184,6 +185,8 @@ readline_lib="" readline_inc="" ncurses_lib="" feat_ipv6=1 +feat_phc=1 +try_phc=0 feat_pps=1 try_setsched=0 try_lockmem=0 @@ -253,6 +256,9 @@ do --disable-ipv6) feat_ipv6=0 ;; + --disable-phc) + feat_phc=0 + ;; --disable-pps) feat_pps=0 ;; @@ -315,6 +321,7 @@ case $SYSTEM in try_rtc=1 try_setsched=1 try_lockmem=1 + try_phc=1 add_def LINUX echo "Configuring for " $SYSTEM if [ "${MACHINE}" = "alpha" ]; then @@ -443,6 +450,13 @@ then add_def FEAT_RTC fi +if [ $feat_phc = "1" ] && [ $try_phc = "1" ] && \ + test_code '' 'sys/ioctl.h linux/ptp_clock.h' '' '' \ + 'ioctl(1, PTP_CLOCK_GETCAPS, 0);' +then + add_def FEAT_PHC +fi + if [ $try_setsched = "1" ] && \ test_code \ 'sched_setscheduler()' \ diff --git a/refclock.c b/refclock.c index 3e47284..89319d5 100644 --- a/refclock.c +++ b/refclock.c @@ -42,6 +42,7 @@ extern RefclockDriver RCL_SHM_driver; extern RefclockDriver RCL_SOCK_driver; extern RefclockDriver RCL_PPS_driver; +extern RefclockDriver RCL_PHC_driver; struct FilterSample { double offset; @@ -166,6 +167,9 @@ RCL_AddRefclock(RefclockParameters *params) inst->driver = &RCL_PPS_driver; inst->precision = 1e-9; pps_source = 1; + } else if (strcmp(params->driver_name, "PHC") == 0) { + inst->driver = &RCL_PHC_driver; + inst->precision = 1e-9; } else { LOG_FATAL(LOGF_Refclock, "unknown refclock driver %s", params->driver_name); return 0; diff --git a/refclock_phc.c b/refclock_phc.c new file mode 100644 index 0000000..a1bfd3d --- /dev/null +++ b/refclock_phc.c @@ -0,0 +1,195 @@ +/* + chronyd/chronyc - Programs for keeping computer clocks accurate. + + ********************************************************************** + * Copyright (C) Miroslav Lichvar 2013 + * + * 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. + * + ********************************************************************** + + ======================================================================= + + PTP hardware clock (PHC) refclock driver. + + */ + +#include "config.h" + +#include "refclock.h" + +#ifdef FEAT_PHC + +#include "sysincl.h" + +#include + +#include "refclock.h" +#include "logging.h" +#include "util.h" + +/* From linux/include/linux/posix-timers.h */ +#define CPUCLOCK_MAX 3 +#define CLOCKFD CPUCLOCK_MAX +#define CLOCKFD_MASK (CPUCLOCK_PERTHREAD_MASK|CPUCLOCK_CLOCK_MASK) + +#define FD_TO_CLOCKID(fd) ((~(clockid_t) (fd) << 3) | CLOCKFD) + +#define NUM_READINGS 10 + +static int no_sys_offset_ioctl = 0; + +struct phc_reading { + struct timespec sys_ts1; + struct timespec phc_ts;; + struct timespec sys_ts2; +}; + +static double diff_ts(struct timespec *ts1, struct timespec *ts2) +{ + return (ts1->tv_sec - ts2->tv_sec) + (ts1->tv_nsec - ts2->tv_nsec) / 1e9; +} + +static int read_phc_ioctl(struct phc_reading *readings, int phc_fd, int n) +{ +#ifdef PTP_SYS_OFFSET + struct ptp_sys_offset sys_off; + int i; + + /* Silence valgrind */ + memset(&sys_off, 0, sizeof (sys_off)); + + sys_off.n_samples = n; + if (ioctl(phc_fd, PTP_SYS_OFFSET, &sys_off)) { + LOG(LOGS_ERR, LOGF_Refclock, "ioctl(PTP_SYS_OFFSET) failed : %s", strerror(errno)); + return 0; + } + + for (i = 0; i < n; i++) { + readings[i].sys_ts1.tv_sec = sys_off.ts[i * 2].sec; + readings[i].sys_ts1.tv_nsec = sys_off.ts[i * 2].nsec; + readings[i].phc_ts.tv_sec = sys_off.ts[i * 2 + 1].sec; + readings[i].phc_ts.tv_nsec = sys_off.ts[i * 2 + 1].nsec; + readings[i].sys_ts2.tv_sec = sys_off.ts[i * 2 + 2].sec; + readings[i].sys_ts2.tv_nsec = sys_off.ts[i * 2 + 2].nsec; + } + + return 1; +#else + /* Not available */ + return 0; +#endif +} + +static int read_phc_user(struct phc_reading *readings, int phc_fd, int n) +{ + clockid_t phc_id; + int i; + + phc_id = FD_TO_CLOCKID(phc_fd); + + for (i = 0; i < n; i++) { + if (clock_gettime(CLOCK_REALTIME, &readings[i].sys_ts1) || + clock_gettime(phc_id, &readings[i].phc_ts) || + clock_gettime(CLOCK_REALTIME, &readings[i].sys_ts2)) { + LOG(LOGS_ERR, LOGF_Refclock, "clock_gettime() failed : %s", strerror(errno)); + return 0; + } + } + + return 1; +} + +static int phc_initialise(RCL_Instance instance) +{ + struct ptp_clock_caps caps; + int phc_fd; + char *path; + + path = RCL_GetDriverParameter(instance); + + phc_fd = open(path, O_RDONLY); + if (phc_fd < 0) { + LOG_FATAL(LOGF_Refclock, "open() failed on %s", path); + return 0; + } + + /* Make sure it is a PHC */ + if (ioctl(phc_fd, PTP_CLOCK_GETCAPS, &caps)) { + LOG_FATAL(LOGF_Refclock, "ioctl(PTP_CLOCK_GETCAPS) failed : %s", strerror(errno)); + return 0; + } + + UTI_FdSetCloexec(phc_fd); + + RCL_SetDriverData(instance, (void *)(long)phc_fd); + return 1; +} + +static void phc_finalise(RCL_Instance instance) +{ + close((long)RCL_GetDriverData(instance)); +} + +static int phc_poll(RCL_Instance instance) +{ + struct phc_reading readings[NUM_READINGS]; + struct timeval tv; + double offset = 0.0, delay, best_delay = 0.0; + int i, phc_fd, best; + + phc_fd = (long)RCL_GetDriverData(instance); + + if (!no_sys_offset_ioctl && NUM_READINGS <= PTP_MAX_SAMPLES) { + if (!read_phc_ioctl(readings, phc_fd, NUM_READINGS)) { + no_sys_offset_ioctl = 1; + return 0; + } + } else { + if (!read_phc_user(readings, phc_fd, NUM_READINGS)) + return 0; + } + + /* Find the fastest reading */ + for (i = 0; i < NUM_READINGS; i++) { + delay = diff_ts(&readings[i].sys_ts2, &readings[i].sys_ts1); + + if (!i || best_delay > delay) { + best = i; + best_delay = delay; + } + } + + offset = diff_ts(&readings[best].phc_ts, &readings[best].sys_ts2) + best_delay / 2.0; + tv.tv_sec = readings[best].sys_ts2.tv_sec; + tv.tv_usec = readings[best].sys_ts2.tv_nsec / 1000; + +#ifdef TRACEON + LOG(LOGS_INFO, LOGF_Refclock, "PHC offset: %+.9f delay: %.9f", offset, best_delay); +#endif + + return RCL_AddSample(instance, &tv, offset, LEAP_Normal); +} + +RefclockDriver RCL_PHC_driver = { + phc_initialise, + phc_finalise, + phc_poll +}; + +#else + +RefclockDriver RCL_PHC_driver = { NULL, NULL, NULL }; + +#endif