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>

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)