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authorRichard Cochran <richardcochran@gmail.com>2011-04-22 12:03:08 +0200
committerJohn Stultz <john.stultz@linaro.org>2011-05-23 13:01:00 -0700
commitd94ba80ebbea17f036cecb104398fbcd788aa742 (patch)
tree7fe40228c5ea2bb77f2892b722d27155df8c1157 /Documentation/ptp
parentcaebc160ce3f76761cc62ad96ef6d6f30f54e3dd (diff)
ptp: Added a brand new class driver for ptp clocks.
This patch adds an infrastructure for hardware clocks that implement IEEE 1588, the Precision Time Protocol (PTP). A class driver offers a registration method to particular hardware clock drivers. Each clock is presented as a standard POSIX clock. The ancillary clock features are exposed in two different ways, via the sysfs and by a character device. Signed-off-by: Richard Cochran <richard.cochran@omicron.at> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'Documentation/ptp')
-rw-r--r--Documentation/ptp/ptp.txt89
-rw-r--r--Documentation/ptp/testptp.c381
-rw-r--r--Documentation/ptp/testptp.mk33
3 files changed, 503 insertions, 0 deletions
diff --git a/Documentation/ptp/ptp.txt b/Documentation/ptp/ptp.txt
new file mode 100644
index 000000000000..ae8fef86b832
--- /dev/null
+++ b/Documentation/ptp/ptp.txt
@@ -0,0 +1,89 @@
+
+* PTP hardware clock infrastructure for Linux
+
+ This patch set introduces support for IEEE 1588 PTP clocks in
+ Linux. Together with the SO_TIMESTAMPING socket options, this
+ presents a standardized method for developing PTP user space
+ programs, synchronizing Linux with external clocks, and using the
+ ancillary features of PTP hardware clocks.
+
+ A new class driver exports a kernel interface for specific clock
+ drivers and a user space interface. The infrastructure supports a
+ complete set of PTP hardware clock functionality.
+
+ + Basic clock operations
+ - Set time
+ - Get time
+ - Shift the clock by a given offset atomically
+ - Adjust clock frequency
+
+ + Ancillary clock features
+ - One short or periodic alarms, with signal delivery to user program
+ - Time stamp external events
+ - Period output signals configurable from user space
+ - Synchronization of the Linux system time via the PPS subsystem
+
+** PTP hardware clock kernel API
+
+ A PTP clock driver registers itself with the class driver. The
+ class driver handles all of the dealings with user space. The
+ author of a clock driver need only implement the details of
+ programming the clock hardware. The clock driver notifies the class
+ driver of asynchronous events (alarms and external time stamps) via
+ a simple message passing interface.
+
+ The class driver supports multiple PTP clock drivers. In normal use
+ cases, only one PTP clock is needed. However, for testing and
+ development, it can be useful to have more than one clock in a
+ single system, in order to allow performance comparisons.
+
+** PTP hardware clock user space API
+
+ The class driver also creates a character device for each
+ registered clock. User space can use an open file descriptor from
+ the character device as a POSIX clock id and may call
+ clock_gettime, clock_settime, and clock_adjtime. These calls
+ implement the basic clock operations.
+
+ User space programs may control the clock using standardized
+ ioctls. A program may query, enable, configure, and disable the
+ ancillary clock features. User space can receive time stamped
+ events via blocking read() and poll(). One shot and periodic
+ signals may be configured via the POSIX timer_settime() system
+ call.
+
+** Writing clock drivers
+
+ Clock drivers include include/linux/ptp_clock_kernel.h and register
+ themselves by presenting a 'struct ptp_clock_info' to the
+ registration method. Clock drivers must implement all of the
+ functions in the interface. If a clock does not offer a particular
+ ancillary feature, then the driver should just return -EOPNOTSUPP
+ from those functions.
+
+ Drivers must ensure that all of the methods in interface are
+ reentrant. Since most hardware implementations treat the time value
+ as a 64 bit integer accessed as two 32 bit registers, drivers
+ should use spin_lock_irqsave/spin_unlock_irqrestore to protect
+ against concurrent access. This locking cannot be accomplished in
+ class driver, since the lock may also be needed by the clock
+ driver's interrupt service routine.
+
+** Supported hardware
+
+ + Freescale eTSEC gianfar
+ - 2 Time stamp external triggers, programmable polarity (opt. interrupt)
+ - 2 Alarm registers (optional interrupt)
+ - 3 Periodic signals (optional interrupt)
+
+ + National DP83640
+ - 6 GPIOs programmable as inputs or outputs
+ - 6 GPIOs with dedicated functions (LED/JTAG/clock) can also be
+ used as general inputs or outputs
+ - GPIO inputs can time stamp external triggers
+ - GPIO outputs can produce periodic signals
+ - 1 interrupt pin
+
+ + Intel IXP465
+ - Auxiliary Slave/Master Mode Snapshot (optional interrupt)
+ - Target Time (optional interrupt)
diff --git a/Documentation/ptp/testptp.c b/Documentation/ptp/testptp.c
new file mode 100644
index 000000000000..f59ded066108
--- /dev/null
+++ b/Documentation/ptp/testptp.c
@@ -0,0 +1,381 @@
+/*
+ * PTP 1588 clock support - User space test program
+ *
+ * Copyright (C) 2010 OMICRON electronics GmbH
+ *
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <errno.h>
+#include <fcntl.h>
+#include <math.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/timex.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <linux/ptp_clock.h>
+
+#define DEVICE "/dev/ptp0"
+
+#ifndef ADJ_SETOFFSET
+#define ADJ_SETOFFSET 0x0100
+#endif
+
+#ifndef CLOCK_INVALID
+#define CLOCK_INVALID -1
+#endif
+
+/* When glibc offers the syscall, this will go away. */
+#include <sys/syscall.h>
+static int clock_adjtime(clockid_t id, struct timex *tx)
+{
+ return syscall(__NR_clock_adjtime, id, tx);
+}
+
+static clockid_t get_clockid(int fd)
+{
+#define CLOCKFD 3
+#define FD_TO_CLOCKID(fd) ((~(clockid_t) (fd) << 3) | CLOCKFD)
+
+ return FD_TO_CLOCKID(fd);
+}
+
+static void handle_alarm(int s)
+{
+ printf("received signal %d\n", s);
+}
+
+static int install_handler(int signum, void (*handler)(int))
+{
+ struct sigaction action;
+ sigset_t mask;
+
+ /* Unblock the signal. */
+ sigemptyset(&mask);
+ sigaddset(&mask, signum);
+ sigprocmask(SIG_UNBLOCK, &mask, NULL);
+
+ /* Install the signal handler. */
+ action.sa_handler = handler;
+ action.sa_flags = 0;
+ sigemptyset(&action.sa_mask);
+ sigaction(signum, &action, NULL);
+
+ return 0;
+}
+
+static long ppb_to_scaled_ppm(int ppb)
+{
+ /*
+ * The 'freq' field in the 'struct timex' is in parts per
+ * million, but with a 16 bit binary fractional field.
+ * Instead of calculating either one of
+ *
+ * scaled_ppm = (ppb / 1000) << 16 [1]
+ * scaled_ppm = (ppb << 16) / 1000 [2]
+ *
+ * we simply use double precision math, in order to avoid the
+ * truncation in [1] and the possible overflow in [2].
+ */
+ return (long) (ppb * 65.536);
+}
+
+static void usage(char *progname)
+{
+ fprintf(stderr,
+ "usage: %s [options]\n"
+ " -a val request a one-shot alarm after 'val' seconds\n"
+ " -A val request a periodic alarm every 'val' seconds\n"
+ " -c query the ptp clock's capabilities\n"
+ " -d name device to open\n"
+ " -e val read 'val' external time stamp events\n"
+ " -f val adjust the ptp clock frequency by 'val' ppb\n"
+ " -g get the ptp clock time\n"
+ " -h prints this message\n"
+ " -p val enable output with a period of 'val' nanoseconds\n"
+ " -P val enable or disable (val=1|0) the system clock PPS\n"
+ " -s set the ptp clock time from the system time\n"
+ " -S set the system time from the ptp clock time\n"
+ " -t val shift the ptp clock time by 'val' seconds\n",
+ progname);
+}
+
+int main(int argc, char *argv[])
+{
+ struct ptp_clock_caps caps;
+ struct ptp_extts_event event;
+ struct ptp_extts_request extts_request;
+ struct ptp_perout_request perout_request;
+ struct timespec ts;
+ struct timex tx;
+
+ static timer_t timerid;
+ struct itimerspec timeout;
+ struct sigevent sigevent;
+
+ char *progname;
+ int c, cnt, fd;
+
+ char *device = DEVICE;
+ clockid_t clkid;
+ int adjfreq = 0x7fffffff;
+ int adjtime = 0;
+ int capabilities = 0;
+ int extts = 0;
+ int gettime = 0;
+ int oneshot = 0;
+ int periodic = 0;
+ int perout = -1;
+ int pps = -1;
+ int settime = 0;
+
+ progname = strrchr(argv[0], '/');
+ progname = progname ? 1+progname : argv[0];
+ while (EOF != (c = getopt(argc, argv, "a:A:cd:e:f:ghp:P:sSt:v"))) {
+ switch (c) {
+ case 'a':
+ oneshot = atoi(optarg);
+ break;
+ case 'A':
+ periodic = atoi(optarg);
+ break;
+ case 'c':
+ capabilities = 1;
+ break;
+ case 'd':
+ device = optarg;
+ break;
+ case 'e':
+ extts = atoi(optarg);
+ break;
+ case 'f':
+ adjfreq = atoi(optarg);
+ break;
+ case 'g':
+ gettime = 1;
+ break;
+ case 'p':
+ perout = atoi(optarg);
+ break;
+ case 'P':
+ pps = atoi(optarg);
+ break;
+ case 's':
+ settime = 1;
+ break;
+ case 'S':
+ settime = 2;
+ break;
+ case 't':
+ adjtime = atoi(optarg);
+ break;
+ case 'h':
+ usage(progname);
+ return 0;
+ case '?':
+ default:
+ usage(progname);
+ return -1;
+ }
+ }
+
+ fd = open(device, O_RDWR);
+ if (fd < 0) {
+ fprintf(stderr, "opening %s: %s\n", device, strerror(errno));
+ return -1;
+ }
+
+ clkid = get_clockid(fd);
+ if (CLOCK_INVALID == clkid) {
+ fprintf(stderr, "failed to read clock id\n");
+ return -1;
+ }
+
+ if (capabilities) {
+ if (ioctl(fd, PTP_CLOCK_GETCAPS, &caps)) {
+ perror("PTP_CLOCK_GETCAPS");
+ } else {
+ printf("capabilities:\n"
+ " %d maximum frequency adjustment (ppb)\n"
+ " %d programmable alarms\n"
+ " %d external time stamp channels\n"
+ " %d programmable periodic signals\n"
+ " %d pulse per second\n",
+ caps.max_adj,
+ caps.n_alarm,
+ caps.n_ext_ts,
+ caps.n_per_out,
+ caps.pps);
+ }
+ }
+
+ if (0x7fffffff != adjfreq) {
+ memset(&tx, 0, sizeof(tx));
+ tx.modes = ADJ_FREQUENCY;
+ tx.freq = ppb_to_scaled_ppm(adjfreq);
+ if (clock_adjtime(clkid, &tx)) {
+ perror("clock_adjtime");
+ } else {
+ puts("frequency adjustment okay");
+ }
+ }
+
+ if (adjtime) {
+ memset(&tx, 0, sizeof(tx));
+ tx.modes = ADJ_SETOFFSET;
+ tx.time.tv_sec = adjtime;
+ tx.time.tv_usec = 0;
+ if (clock_adjtime(clkid, &tx) < 0) {
+ perror("clock_adjtime");
+ } else {
+ puts("time shift okay");
+ }
+ }
+
+ if (gettime) {
+ if (clock_gettime(clkid, &ts)) {
+ perror("clock_gettime");
+ } else {
+ printf("clock time: %ld.%09ld or %s",
+ ts.tv_sec, ts.tv_nsec, ctime(&ts.tv_sec));
+ }
+ }
+
+ if (settime == 1) {
+ clock_gettime(CLOCK_REALTIME, &ts);
+ if (clock_settime(clkid, &ts)) {
+ perror("clock_settime");
+ } else {
+ puts("set time okay");
+ }
+ }
+
+ if (settime == 2) {
+ clock_gettime(clkid, &ts);
+ if (clock_settime(CLOCK_REALTIME, &ts)) {
+ perror("clock_settime");
+ } else {
+ puts("set time okay");
+ }
+ }
+
+ if (extts) {
+ memset(&extts_request, 0, sizeof(extts_request));
+ extts_request.index = 0;
+ extts_request.flags = PTP_ENABLE_FEATURE;
+ if (ioctl(fd, PTP_EXTTS_REQUEST, &extts_request)) {
+ perror("PTP_EXTTS_REQUEST");
+ extts = 0;
+ } else {
+ puts("external time stamp request okay");
+ }
+ for (; extts; extts--) {
+ cnt = read(fd, &event, sizeof(event));
+ if (cnt != sizeof(event)) {
+ perror("read");
+ break;
+ }
+ printf("event index %u at %lld.%09u\n", event.index,
+ event.t.sec, event.t.nsec);
+ fflush(stdout);
+ }
+ /* Disable the feature again. */
+ extts_request.flags = 0;
+ if (ioctl(fd, PTP_EXTTS_REQUEST, &extts_request)) {
+ perror("PTP_EXTTS_REQUEST");
+ }
+ }
+
+ if (oneshot) {
+ install_handler(SIGALRM, handle_alarm);
+ /* Create a timer. */
+ sigevent.sigev_notify = SIGEV_SIGNAL;
+ sigevent.sigev_signo = SIGALRM;
+ if (timer_create(clkid, &sigevent, &timerid)) {
+ perror("timer_create");
+ return -1;
+ }
+ /* Start the timer. */
+ memset(&timeout, 0, sizeof(timeout));
+ timeout.it_value.tv_sec = oneshot;
+ if (timer_settime(timerid, 0, &timeout, NULL)) {
+ perror("timer_settime");
+ return -1;
+ }
+ pause();
+ timer_delete(timerid);
+ }
+
+ if (periodic) {
+ install_handler(SIGALRM, handle_alarm);
+ /* Create a timer. */
+ sigevent.sigev_notify = SIGEV_SIGNAL;
+ sigevent.sigev_signo = SIGALRM;
+ if (timer_create(clkid, &sigevent, &timerid)) {
+ perror("timer_create");
+ return -1;
+ }
+ /* Start the timer. */
+ memset(&timeout, 0, sizeof(timeout));
+ timeout.it_interval.tv_sec = periodic;
+ timeout.it_value.tv_sec = periodic;
+ if (timer_settime(timerid, 0, &timeout, NULL)) {
+ perror("timer_settime");
+ return -1;
+ }
+ while (1) {
+ pause();
+ }
+ timer_delete(timerid);
+ }
+
+ if (perout >= 0) {
+ if (clock_gettime(clkid, &ts)) {
+ perror("clock_gettime");
+ return -1;
+ }
+ memset(&perout_request, 0, sizeof(perout_request));
+ perout_request.index = 0;
+ perout_request.start.sec = ts.tv_sec + 2;
+ perout_request.start.nsec = 0;
+ perout_request.period.sec = 0;
+ perout_request.period.nsec = perout;
+ if (ioctl(fd, PTP_PEROUT_REQUEST, &perout_request)) {
+ perror("PTP_PEROUT_REQUEST");
+ } else {
+ puts("periodic output request okay");
+ }
+ }
+
+ if (pps != -1) {
+ int enable = pps ? 1 : 0;
+ if (ioctl(fd, PTP_ENABLE_PPS, enable)) {
+ perror("PTP_ENABLE_PPS");
+ } else {
+ puts("pps for system time request okay");
+ }
+ }
+
+ close(fd);
+ return 0;
+}
diff --git a/Documentation/ptp/testptp.mk b/Documentation/ptp/testptp.mk
new file mode 100644
index 000000000000..4ef2d9755421
--- /dev/null
+++ b/Documentation/ptp/testptp.mk
@@ -0,0 +1,33 @@
+# PTP 1588 clock support - User space test program
+#
+# Copyright (C) 2010 OMICRON electronics GmbH
+#
+# 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+CC = $(CROSS_COMPILE)gcc
+INC = -I$(KBUILD_OUTPUT)/usr/include
+CFLAGS = -Wall $(INC)
+LDLIBS = -lrt
+PROGS = testptp
+
+all: $(PROGS)
+
+testptp: testptp.o
+
+clean:
+ rm -f testptp.o
+
+distclean: clean
+ rm -f $(PROGS)

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