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>

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)

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;
+}

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)