Re: [PATCH] LinuxPPS - PPS support for Linux

[Rodolfo Giometti]

On Tue, Oct 23, 2007 at 04:17:50PM -0400, Dave Jones wrote:
> 
> On the whole, asides from these (very) minor nits, quite a clean
> submission compared to a lot of new driver submissions to lkml.
> Might want to run it through scripts/checkpatch.pl too to see
> if that picks up any more minor fluff.

Here the ./scripts/checkpatch.pl output:

   $ ./scripts/checkpatch.pl patch 
   WARNING: do not add new typedefs
   #522: FILE: Documentation/pps/timepps.h:59:
   +typedef int pps_handle_t;		/* represents a PPS source */

   WARNING: do not add new typedefs
   #523: FILE: Documentation/pps/timepps.h:60:
   +typedef unsigned long pps_seq_t;	/* sequence number */

   WARNING: do not add new typedefs
   #524: FILE: Documentation/pps/timepps.h:61:
   +typedef struct ntp_fp ntp_fp_t;		/* NTP-compatible time stamp */

   WARNING: do not add new typedefs
   #525: FILE: Documentation/pps/timepps.h:62:
   +typedef union pps_timeu pps_timeu_t;	/* generic data type for time stamps */

   WARNING: do not add new typedefs
   #526: FILE: Documentation/pps/timepps.h:63:
   +typedef struct pps_info pps_info_t;

   WARNING: do not add new typedefs
   #527: FILE: Documentation/pps/timepps.h:64:
   +typedef struct pps_params pps_params_t;

These refere to an userland include file.

   WARNING: line over 80 characters
   #1882: FILE: drivers/serial/serial_core.c:871:
   +		if (((old_flags ^ port->flags) & (UPF_SPD_MASK|UPF_HARDPPS_CD)) ||

   ERROR: need consistent spacing around '|' (ctx:WxV)
   #2191: FILE: include/linux/serial_core.h:288:
   +							|UPF_HARDPPS_CD))
                                                        ^
These refere to previous code.

   ERROR: Missing Signed-off-by: line(s)

   Your patch has style problems, please review.  If any of these errors
   are false positives report them to the maintainer, see
   CHECKPATCH in MAINTAINERS.

Attached the new patch.

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti@xxxxxxxxxxxx
Linux Device Driver                             giometti@xxxxxxxxx
Embedded Systems                     		giometti@xxxxxxxx
UNIX programming                     phone:     +39 349 2432127
diff --git a/Documentation/pps/Makefile b/Documentation/pps/Makefile
new file mode 100644
index 0000000..a2660a2
--- /dev/null
+++ b/Documentation/pps/Makefile
@@ -0,0 +1,27 @@
+TARGETS = ppstest ppsctl
+
+CFLAGS += -Wall -O2 -D_GNU_SOURCE
+CFLAGS += -I .
+CFLAGS += -ggdb
+
+# -- Actions section ----------------------------------------------------------
+
+.PHONY : all depend dep
+
+all : .depend $(TARGETS)
+
+.depend depend dep :
+	$(CC) $(CFLAGS) -M $(TARGETS:=.c) > .depend
+
+ifeq (.depend,$(wildcard .depend))
+include .depend
+endif
+
+
+# -- Clean section ------------------------------------------------------------
+
+.PHONY : clean
+
+clean :
+	rm -f *.o *~ core .depend
+	rm -f ${TARGETS}
diff --git a/Documentation/pps/pps.txt b/Documentation/pps/pps.txt
new file mode 100644
index 0000000..9538925
--- /dev/null
+++ b/Documentation/pps/pps.txt
@@ -0,0 +1,170 @@
+
+			PPS - Pulse Per Second
+			----------------------
+
+(C) Copyright 2007 Rodolfo Giometti <giometti@xxxxxxxxxxxx>
+
+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.
+
+
+
+Overview
+--------
+
+LinuxPPS provides a programming interface (API) to define into the
+system several PPS sources.
+
+PPS means "pulse per second" and a PPS source is just a device which
+provides a high precision signal each second so that an application
+can use it to adjust system clock time.
+
+A PPS source can be connected to a serial port (usually to the Data
+Carrier Detect pin) or to a parallel port (ACK-pin) or to a special
+CPU's GPIOs (this is the common case in embedded systems) but in each
+case when a new pulse comes the system must apply to it a timestamp
+and record it for the userland.
+
+Common use is the combination of the NTPD as userland program with a
+GPS receiver as PPS source to obtain a wallclock-time with
+sub-millisecond synchronisation to UTC.
+
+
+RFC considerations
+------------------
+
+While implementing a PPS API as RFC 2783 defines and using an embedded
+CPU GPIO-Pin as physical link to the signal, I encountered a deeper
+problem:
+
+   At startup it needs a file descriptor as argument for the function
+   time_pps_create().
+
+This implies that the source has a /dev/... entry. This assumption is
+ok for the serial and parallel port, where you can do something
+useful besides(!) the gathering of timestamps as it is the central
+task for a PPS-API. But this assumption does not work for a single
+purpose GPIO line. In this case even basic file-related functionality
+(like read() and write()) makes no sense at all and should not be a
+precondition for the use of a PPS-API.
+
+The problem can be simply solved if you consider that a PPS source is
+not always connected with a GPS data source.
+
+So your programs should check if the GPS data source (the serial port
+for instance) is a PPS source too, otherwise they should provide the
+possibility to open another device as PPS source.
+
+In LinuxPPS the PPS sources are simply char devices usually mapped
+into files /dev/pps0, /dev/pps1, etc..
+
+
+Coding example
+--------------
+
+To register a PPS source into the kernel you should define a struct
+pps_source_info_s as follow:
+
+    static struct pps_source_info_s pps_ktimer_info = {
+            name         : "ktimer",
+            path         : "",
+            mode         : PPS_CAPTUREASSERT | PPS_OFFSETASSERT | \
+			   PPS_ECHOASSERT | \
+                           PPS_CANWAIT | PPS_TSFMT_TSPEC,
+            echo         : pps_ktimer_echo,
+            owner        : THIS_MODULE,
+    };
+
+and then calling the function pps_register_source() in your
+intialization routine as follow:
+
+    source = pps_register_source(&pps_ktimer_info,
+			PPS_CAPTUREASSERT | PPS_OFFSETASSERT);
+
+The pps_register_source() prototype is:
+
+  int pps_register_source(struct pps_source_info_s *info, int default_params)
+
+where "info" is a pointer to a structure that describes a particular
+PPS source, "default_params" tells the system what the initial default
+parameters for the device should be (is obvious that these parameters
+must be a subset of ones defined into the struct
+pps_source_info_s which describe the capabilities of the driver).
+
+Once you have registered a new PPS source into the system you can
+signal an assert event (for example in the interrupt handler routine)
+just using:
+
+    pps_event(source, PPS_CAPTUREASSERT, ptr);
+
+The same function may also run the defined echo function
+(pps_ktimer_echo(), passing to it the "ptr" pointer) if the user
+asked for that... etc..
+
+Please see the file drivers/pps/clients/ktimer.c for an example code.
+
+
+SYSFS support
+-------------
+
+If the SYSFS filesystem is enabled in the kernel it provides a new class:
+
+   $ ls /sys/class/pps/
+   pps0/  pps1/  pps2/
+
+Every directory is the ID of a PPS sources defined into the system and
+inside you find several files:
+
+    $ ls /sys/class/pps/pps0/
+    assert	clear  echo  mode  name  path  subsystem@  uevent
+
+Inside each "assert" and "clear" file you can find the timestamp and a
+sequence number:
+
+    $ cat /sys/class/pps/pps0/assert
+    1170026870.983207967#8
+
+Where before the "#" is the timestamp in seconds and after it is the
+sequence number. Other files are:
+
+* echo: reports if the PPS source has an echo function or not;
+
+* mode: reports available PPS functioning modes;
+
+* name: reports the PPS source's name;
+
+* path: reports the PPS source's device path, that is the device the
+  PPS source is connected to (if it exists).
+
+
+Testing the PPS support
+-----------------------
+
+In order to test the PPS support even without specific hardware you can use
+the ktimer driver (see the client subsection in the PPS configuration menu)
+and the userland tools provided into Documentaion/pps/ directory.
+
+Once you have enabled the compilation of ktimer just modprobe it (if
+not statically compiled):
+
+   # modprobe ktimer
+
+and the run ppstest as follow:
+
+   $ ./ppstest /dev/pps0
+   trying PPS source "/dev/pps1"
+   found PPS source "/dev/pps1"
+   ok, found 1 source(s), now start fetching data...
+   source 0 - assert 1186592699.388832443, sequence: 364 - clear  0.000000000, sequence: 0
+   source 0 - assert 1186592700.388931295, sequence: 365 - clear  0.000000000, sequence: 0
+   source 0 - assert 1186592701.389032765, sequence: 366 - clear  0.000000000, sequence: 0
+
+Please, note that to compile userland programs you need the file timepps.h
+(see Documentation/pps/).
diff --git a/Documentation/pps/ppsctl.c b/Documentation/pps/ppsctl.c
new file mode 100644
index 0000000..83fd08a
--- /dev/null
+++ b/Documentation/pps/ppsctl.c
@@ -0,0 +1,62 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <string.h>
+#include <linux/serial.h>
+
+void usage(char *name)
+{
+	fprintf(stderr, "usage: %s <ttyS> [enable|disable]\n", name);
+
+	exit(EXIT_FAILURE);
+}
+
+int main(int argc, char *argv[])
+{
+	int fd;
+	int ret;
+	struct serial_struct ss;
+
+	if (argc < 2)
+		usage(argv[0]);
+
+	fd = open(argv[1], O_RDWR);
+	if (fd < 0) {
+		perror("open");
+		exit(EXIT_FAILURE);
+	}
+
+	ret = ioctl(fd, TIOCGSERIAL, &ss);
+	if (ret < 0) {
+		perror("ioctl(TIOCGSERIAL)");
+		exit(EXIT_FAILURE);
+	}
+
+	if (argc < 3) {		/* just read PPS status */
+		printf("PPS is %sabled\n",
+		       ss.flags & ASYNC_HARDPPS_CD ? "en" : "dis");
+		exit(EXIT_SUCCESS);
+	}
+
+	if (argv[2][0] == 'e' || argv[2][0] == '1')
+		ss.flags |= ASYNC_HARDPPS_CD;
+	else if (argv[2][0] == 'd' || argv[2][0] == '0')
+		ss.flags &= ~ASYNC_HARDPPS_CD;
+	else {
+		fprintf(stderr, "invalid state argument \"%s\"\n", argv[2]);
+		exit(EXIT_FAILURE);
+	}
+
+	ret = ioctl(fd, TIOCSSERIAL, &ss);
+	if (ret < 0) {
+		perror("ioctl(TIOCSSERIAL)");
+		exit(EXIT_FAILURE);
+	}
+
+	return 0;
+}
diff --git a/Documentation/pps/ppsfind b/Documentation/pps/ppsfind
new file mode 100755
index 0000000..93c0e17
--- /dev/null
+++ b/Documentation/pps/ppsfind
@@ -0,0 +1,17 @@
+#!/bin/sh
+
+SYS="/sys/class/pps/"
+
+if [ $# -lt 1 ] ; then
+	echo "usage: ppsfind <name>" >&2
+	exit 1
+fi
+
+for d in $(ls $SYS) ; do
+	if grep $1 $SYS/$d/name >& /dev/null || \
+	   grep $1 $SYS/$d/path >& /dev/null ; then
+		echo "$d: name=$(cat $SYS/$d/name) path=$(cat $SYS/$d/path)"
+	fi
+done
+
+exit 0
diff --git a/Documentation/pps/ppstest.c b/Documentation/pps/ppstest.c
new file mode 100644
index 0000000..d125ffa
--- /dev/null
+++ b/Documentation/pps/ppstest.c
@@ -0,0 +1,151 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include <timepps.h>
+
+int find_source(char *path, pps_handle_t *handle, int *avail_mode)
+{
+	pps_params_t params;
+	int ret;
+
+	printf("trying PPS source \"%s\"\n", path);
+
+	/* Try to find the source by using the supplied "path" name */
+	ret = open(path, O_RDWR);
+	if (ret < 0) {
+		fprintf(stderr, "unable to open device \"%s\" (%m)\n", path);
+		return ret;
+	}
+
+	/* Open the PPS source (and check the file descriptor) */
+	ret = time_pps_create(ret, handle);
+	if (ret < 0) {
+		fprintf(stderr, "cannot create a PPS source from device "
+				"\"%s\" (%m)\n", path);
+		return -1;
+	}
+	printf("found PPS source \"%s\"\n", path);
+
+	/* Find out what features are supported */
+	ret = time_pps_getcap(*handle, avail_mode);
+	if (ret < 0) {
+		fprintf(stderr, "cannot get capabilities (%m)\n");
+		return -1;
+	}
+	if ((*avail_mode & PPS_CAPTUREASSERT) == 0) {
+		fprintf(stderr, "cannot CAPTUREASSERT\n");
+		return -1;
+	}
+	if ((*avail_mode & PPS_OFFSETASSERT) == 0) {
+		fprintf(stderr, "cannot OFFSETASSERT\n");
+		return -1;
+	}
+
+	/* Capture assert timestamps, and compensate for a 675 nsec
+	 * propagation delay */
+	ret = time_pps_getparams(*handle, &params);
+	if (ret < 0) {
+		fprintf(stderr, "cannot get parameters (%m)\n");
+		return -1;
+	}
+	params.assert_offset.tv_sec = 0;
+	params.assert_offset.tv_nsec = 675;
+	params.mode |= PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
+	ret = time_pps_setparams(*handle, &params);
+	if (ret < 0) {
+		fprintf(stderr, "cannot set parameters (%m)\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+int fetch_source(int i, pps_handle_t *handle, int *avail_mode)
+{
+	struct timespec timeout;
+	pps_info_t infobuf;
+	int ret;
+
+	/* create a zero-valued timeout */
+	timeout.tv_sec = 3;
+	timeout.tv_nsec = 0;
+
+retry:
+	if (*avail_mode & PPS_CANWAIT) /* waits for the next event */
+		ret = time_pps_fetch(*handle, PPS_TSFMT_TSPEC, &infobuf,
+				   &timeout);
+	else {
+		sleep(1);
+		ret = time_pps_fetch(*handle, PPS_TSFMT_TSPEC, &infobuf,
+				   &timeout);
+	}
+	if (ret < 0) {
+		if (ret == -EINTR) {
+			fprintf(stderr, "time_pps_fetch() got a signal!\n");
+			goto retry;
+		}
+
+		fprintf(stderr, "time_pps_fetch() error %d (%m)\n", ret);
+		return -1;
+	}
+
+	printf("source %d - "
+	       "assert %ld.%09ld, sequence: %ld - "
+	       "clear  %ld.%09ld, sequence: %ld\n",
+	       i,
+	       infobuf.assert_timestamp.tv_sec,
+	       infobuf.assert_timestamp.tv_nsec,
+	       infobuf.assert_sequence,
+	       infobuf.clear_timestamp.tv_sec,
+	       infobuf.clear_timestamp.tv_nsec, infobuf.clear_sequence);
+
+	return 0;
+}
+
+void usage(char *name)
+{
+	fprintf(stderr, "usage: %s <ppsdev> [<ppsdev> ...]\n", name);
+	exit(EXIT_FAILURE);
+}
+
+int main(int argc, char *argv[])
+{
+	int num;
+	pps_handle_t handle[4];
+	int avail_mode[4];
+	int i = 0;
+	int ret;
+
+	/* Check the command line */
+	if (argc < 2)
+		usage(argv[0]);
+
+	for (i = 1; i < argc && i <= 4; i++) {
+		ret = find_source(argv[i], &handle[i - 1], &avail_mode[i - 1]);
+		if (ret < 0)
+			exit(EXIT_FAILURE);
+	}
+
+	num = i - 1;
+	printf("ok, found %d source(s), now start fetching data...\n", num);
+
+	/* loop, printing the most recent timestamp every second or so */
+	while (1) {
+		for (i = 0; i < num; i++) {
+			ret = fetch_source(i, &handle[i], &avail_mode[i]);
+			if (ret < 0 && errno != ETIMEDOUT)
+				exit(EXIT_FAILURE);
+		}
+	}
+
+	for (; i >= 0; i--)
+		time_pps_destroy(handle[i]);
+
+	return 0;
+}
diff --git a/Documentation/pps/timepps.h b/Documentation/pps/timepps.h
new file mode 100644
index 0000000..28ebf4c
--- /dev/null
+++ b/Documentation/pps/timepps.h
@@ -0,0 +1,193 @@
+/*
+ * timepps.h -- PPS API main header
+ *
+ * Copyright (C) 2005-2007   Rodolfo Giometti <giometti@xxxxxxxx>
+ *
+ *   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.
+ */
+
+#ifndef _SYS_TIMEPPS_H_
+#define _SYS_TIMEPPS_H_
+
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <errno.h>
+#include <linux/pps.h>
+
+/*
+ * New data structures
+ */
+
+struct ntp_fp {
+	unsigned int integral;
+	unsigned int fractional;
+};
+
+union pps_timeu {
+	struct timespec tspec;
+	struct ntp_fp ntpfp;
+	unsigned long longpad[3];
+};
+
+struct pps_info {
+	unsigned long assert_sequence;	/* seq. num. of assert event */
+	unsigned long clear_sequence;	/* seq. num. of clear event */
+	union pps_timeu assert_tu;	/* time of assert event */
+	union pps_timeu clear_tu;	/* time of clear event */
+	int current_mode;		/* current mode bits */
+};
+
+struct pps_params {
+	int api_version;		/* API version # */
+	int mode;			/* mode bits */
+	union pps_timeu assert_off_tu;	/* offset compensation for assert */
+	union pps_timeu clear_off_tu;	/* offset compensation for clear */
+};
+
+typedef int pps_handle_t;		/* represents a PPS source */
+typedef unsigned long pps_seq_t;	/* sequence number */
+typedef struct ntp_fp ntp_fp_t;		/* NTP-compatible time stamp */
+typedef union pps_timeu pps_timeu_t;	/* generic data type for time stamps */
+typedef struct pps_info pps_info_t;
+typedef struct pps_params pps_params_t;
+
+#define assert_timestamp        assert_tu.tspec
+#define clear_timestamp         clear_tu.tspec
+
+#define assert_timestamp_ntpfp  assert_tu.ntpfp
+#define clear_timestamp_ntpfp   clear_tu.ntpfp
+
+#define assert_offset		assert_off_tu.tspec
+#define clear_offset		clear_off_tu.tspec
+
+#define assert_offset_ntpfp     assert_off_tu.ntpfp
+#define clear_offset_ntpfp      clear_off_tu.ntpfp
+
+/*
+ * The PPS API
+ */
+
+static __inline int time_pps_create(int source, pps_handle_t *handle)
+{
+	int ret;
+
+	if (!handle) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	/* First we check if current device is a PPS valid PPS one...
+	 */
+	ret = ioctl(source, PPS_CHECK);
+	if (ret) {
+		errno = EOPNOTSUPP;
+		return -1;
+	}
+
+	/* ... then since in LinuxPPS there are no differences between a
+	 * "PPS source" and a "PPS handle", we simply return the same value.
+	 */
+	*handle = source;
+
+	return 0;
+}
+
+static __inline int time_pps_destroy(pps_handle_t handle)
+{
+	return close(handle);
+}
+
+static __inline int time_pps_getparams(pps_handle_t handle,
+					pps_params_t *ppsparams)
+{
+	int ret;
+	struct pps_kparams __ppsparams;
+
+	ret = ioctl(handle, PPS_GETPARAMS, &__ppsparams);
+
+	ppsparams->api_version = __ppsparams.api_version;
+	ppsparams->mode = __ppsparams.mode;
+	ppsparams->assert_off_tu.tspec.tv_sec = __ppsparams.assert_off_tu.sec;
+	ppsparams->assert_off_tu.tspec.tv_nsec = __ppsparams.assert_off_tu.nsec;
+	ppsparams->clear_off_tu.tspec.tv_sec = __ppsparams.clear_off_tu.sec;
+	ppsparams->clear_off_tu.tspec.tv_nsec = __ppsparams.clear_off_tu.nsec;
+
+	return ret;
+}
+
+static __inline int time_pps_setparams(pps_handle_t handle,
+					const pps_params_t *ppsparams)
+{
+	struct pps_kparams __ppsparams;
+
+	__ppsparams.api_version = ppsparams->api_version;
+	__ppsparams.mode = ppsparams->mode;
+	__ppsparams.assert_off_tu.sec = ppsparams->assert_off_tu.tspec.tv_sec;
+	__ppsparams.assert_off_tu.nsec = ppsparams->assert_off_tu.tspec.tv_nsec;
+	__ppsparams.clear_off_tu.sec = ppsparams->clear_off_tu.tspec.tv_sec;
+	__ppsparams.clear_off_tu.nsec = ppsparams->clear_off_tu.tspec.tv_nsec;
+
+	return ioctl(handle, PPS_SETPARAMS, &__ppsparams);
+}
+
+/* Get capabilities for handle */
+static __inline int time_pps_getcap(pps_handle_t handle, int *mode)
+{
+	return ioctl(handle, PPS_GETCAP, mode);
+}
+
+static __inline int time_pps_fetch(pps_handle_t handle, const int tsformat,
+					pps_info_t *ppsinfobuf,
+					const struct timespec *timeout)
+{
+	struct pps_fdata __fdata;
+	int ret;
+
+	/* Sanity checks */
+	if (tsformat != PPS_TSFMT_TSPEC) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	if (timeout) {
+		__fdata.timeout.sec = timeout->tv_sec;
+		__fdata.timeout.nsec = timeout->tv_nsec;
+		__fdata.timeout.flags = ~PPS_TIME_INVALID;
+	} else
+		__fdata.timeout.flags = PPS_TIME_INVALID;
+
+	ret = ioctl(handle, PPS_FETCH, &__fdata);
+
+	ppsinfobuf->assert_sequence = __fdata.info.assert_sequence;
+	ppsinfobuf->clear_sequence = __fdata.info.clear_sequence;
+	ppsinfobuf->assert_tu.tspec.tv_sec = __fdata.info.assert_tu.sec;
+	ppsinfobuf->assert_tu.tspec.tv_nsec = __fdata.info.assert_tu.nsec;
+	ppsinfobuf->clear_tu.tspec.tv_sec = __fdata.info.clear_tu.sec;
+	ppsinfobuf->clear_tu.tspec.tv_nsec = __fdata.info.clear_tu.nsec;
+	ppsinfobuf->current_mode = __fdata.info.current_mode;
+
+	return ret;
+}
+
+static __inline int time_pps_kcbind(pps_handle_t handle,
+					const int kernel_consumer,
+					const int edge, const int tsformat)
+{
+	/* LinuxPPS doesn't implement kernel consumer feature */
+	errno = EOPNOTSUPP;
+	return -1;
+}
+
+#endif				/* _SYS_TIMEPPS_H_ */
diff --git a/MAINTAINERS b/MAINTAINERS
index 9a91d9e..f45e974 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3011,6 +3011,13 @@ P:	James Chapman
 M:	jchapman@xxxxxxxxxxx
 S:	Maintained
 
+PPS SUPPORT
+P:	Rodolfo Giometti
+M:	giometti@xxxxxxxxxxxx
+W:	http://wiki.enneenne.com/index.php/LinuxPPS_support
+L:	linuxpps@xxxxxxxxxxxxxxx
+S:	Maintained
+
 PREEMPTIBLE KERNEL
 P:	Robert Love
 M:	rml@xxxxxxxxx
diff --git a/drivers/Kconfig b/drivers/Kconfig
index 3e1c442..bffc48e 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -52,6 +52,8 @@ source "drivers/i2c/Kconfig"
 
 source "drivers/spi/Kconfig"
 
+source "drivers/pps/Kconfig"
+
 source "drivers/w1/Kconfig"
 
 source "drivers/power/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
index f0878b2..2e84e49 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -63,6 +63,7 @@ obj-$(CONFIG_INPUT)		+= input/
 obj-$(CONFIG_I2O)		+= message/
 obj-$(CONFIG_RTC_LIB)		+= rtc/
 obj-y				+= i2c/
+obj-$(CONFIG_PPS)		+= pps/
 obj-$(CONFIG_W1)		+= w1/
 obj-$(CONFIG_POWER_SUPPLY)	+= power/
 obj-$(CONFIG_HWMON)		+= hwmon/
diff --git a/drivers/char/lp.c b/drivers/char/lp.c
index 62051f8..e0a8364 100644
--- a/drivers/char/lp.c
+++ b/drivers/char/lp.c
@@ -746,6 +746,27 @@ static struct console lpcons = {
 
 #endif /* console on line printer */
 
+/* Support for PPS signal on the line printer */
+
+#ifdef CONFIG_PPS_CLIENT_LP
+
+static void lp_pps_echo(int source, int event, void *data)
+{
+	struct parport *port = data;
+	unsigned char status = parport_read_status(port);
+
+	/* echo event via SEL bit */
+	parport_write_control(port,
+		parport_read_control(port) | PARPORT_CONTROL_SELECT);
+
+	/* signal no event */
+	if ((status & PARPORT_STATUS_ACK) != 0)
+		parport_write_control(port,
+			parport_read_control(port) & ~PARPORT_CONTROL_SELECT);
+}
+
+#endif
+
 /* --- initialisation code ------------------------------------- */
 
 static int parport_nr[LP_NO] = { [0 ... LP_NO-1] = LP_PARPORT_UNSPEC };
@@ -817,6 +838,38 @@ static int lp_register(int nr, struct parport *port)
 	}
 #endif
 
+#ifdef CONFIG_PPS_CLIENT_LP
+	port->pps_info.owner = THIS_MODULE;
+	port->pps_info.dev = port->dev;
+	snprintf(port->pps_info.path, PPS_MAX_NAME_LEN, "/dev/lp%d", nr);
+
+	/* No PPS support if lp port has no IRQ line */
+	if (port->irq != PARPORT_IRQ_NONE) {
+		strncpy(port->pps_info.name, port->name, PPS_MAX_NAME_LEN);
+
+		port->pps_info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT | \
+				PPS_ECHOASSERT | \
+				PPS_CANWAIT | PPS_TSFMT_TSPEC;
+
+		port->pps_info.echo = lp_pps_echo;
+
+		port->pps_source = pps_register_source(&(port->pps_info),
+				PPS_CAPTUREASSERT | PPS_OFFSETASSERT);
+		if (port->pps_source < 0)
+			dev_err(port->dev,
+					"cannot register PPS source \"%s\"\n",
+					port->pps_info.path);
+		else
+			dev_info(port->dev, "PPS source #%d \"%s\" added\n",
+					port->pps_source, port->pps_info.path);
+	} else {
+		port->pps_source = -1;
+		dev_err(port->dev, "PPS support disabled due port \"%s\" is "
+					"in polling mode\n",
+					port->pps_info.path);
+	}
+#endif
+
 	return 0;
 }
 
@@ -860,6 +913,14 @@ static void lp_detach (struct parport *port)
 		console_registered = NULL;
 	}
 #endif /* CONFIG_LP_CONSOLE */
+
+#ifdef CONFIG_PPS_CLIENT_LP
+	if (port->pps_source >= 0) {
+		pps_unregister_source(port->pps_source);
+		dev_dbg(port->dev, "PPS source #%d \"%s\" removed\n",
+			port->pps_source, port->pps_info.path);
+	}
+#endif
 }
 
 static struct parport_driver lp_driver = {
diff --git a/drivers/pps/Kconfig b/drivers/pps/Kconfig
new file mode 100644
index 0000000..bfe6621
--- /dev/null
+++ b/drivers/pps/Kconfig
@@ -0,0 +1,34 @@
+#
+# PPS support configuration
+#
+
+menu "PPS support"
+
+config PPS
+	tristate "PPS support"
+	depends on EXPERIMENTAL
+	---help---
+	  PPS (Pulse Per Second) is a special pulse provided by some GPS
+	  antennae. Userland can use it to get an high time reference.
+
+	  Some antennae's PPS signals are connected with the CD (Carrier
+	  Detect) pin of the serial line they use to communicate with the
+	  host. In this case use the SERIAL_LINE client support.
+
+	  Some antennae's PPS signals are connected with some special host
+	  inputs so you have to enable the corresponding client support.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pps_core.ko.
+
+config PPS_DEBUG
+	bool "PPS debugging messages"
+	depends on PPS 
+	help
+	  Say Y here if you want the PPS support to produce a bunch of debug
+	  messages to the system log.  Select this if you are having a
+	  problem with PPS support and want to see more of what is going on.
+
+source drivers/pps/clients/Kconfig
+
+endmenu
diff --git a/drivers/pps/Makefile b/drivers/pps/Makefile
new file mode 100644
index 0000000..d8ec308
--- /dev/null
+++ b/drivers/pps/Makefile
@@ -0,0 +1,11 @@
+#
+# Makefile for the PPS core.
+#
+
+pps_core-objs			+= pps.o kapi.o sysfs.o
+obj-$(CONFIG_PPS)		+= pps_core.o
+obj-y				+= clients/
+
+ifeq ($(CONFIG_PPS_DEBUG),y)
+EXTRA_CFLAGS += -DDEBUG
+endif
diff --git a/drivers/pps/clients/Kconfig b/drivers/pps/clients/Kconfig
new file mode 100644
index 0000000..09ba5c3
--- /dev/null
+++ b/drivers/pps/clients/Kconfig
@@ -0,0 +1,38 @@
+#
+# PPS clients configuration
+#
+
+if PPS
+
+comment "PPS clients support"
+
+config PPS_CLIENT_KTIMER
+	tristate "Kernel timer client (Testing client, use for debug)"
+	help
+	  If you say yes here you get support for a PPS debugging client
+	  which uses a kernel timer to generate the PPS signal.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called ktimer.ko.
+
+comment "UART serial support (forced off)"
+	depends on ! (SERIAL_CORE != n && !(PPS = m && SERIAL_CORE = y))
+
+config PPS_CLIENT_UART
+	bool "UART serial support"
+	depends on SERIAL_CORE != n && !(PPS = m && SERIAL_CORE = y)
+	help
+	  If you say yes here you get support for a PPS source connected
+	  with the CD (Carrier Detect) pin of your serial port.
+
+comment "Parallel printer support (forced off)"
+	depends on !( PRINTER != n && !(PPS = m && PRINTER = y))
+
+config PPS_CLIENT_LP
+	bool "Parallel printer support"
+	depends on PRINTER != n && !(PPS = m && PRINTER = y)
+	help
+	  If you say yes here you get support for a PPS source connected
+	  with the interrupt pin of your parallel port.
+
+endif
diff --git a/drivers/pps/clients/Makefile b/drivers/pps/clients/Makefile
new file mode 100644
index 0000000..f3c1e39
--- /dev/null
+++ b/drivers/pps/clients/Makefile
@@ -0,0 +1,9 @@
+#
+# Makefile for PPS clients.
+#
+
+obj-$(CONFIG_PPS_CLIENT_KTIMER)	+= ktimer.o
+
+ifeq ($(CONFIG_PPS_DEBUG),y)
+EXTRA_CFLAGS += -DDEBUG
+endif
diff --git a/drivers/pps/clients/ktimer.c b/drivers/pps/clients/ktimer.c
new file mode 100644
index 0000000..5845188
--- /dev/null
+++ b/drivers/pps/clients/ktimer.c
@@ -0,0 +1,114 @@
+/*
+ * ktimer.c -- kernel timer test client
+ *
+ *
+ * Copyright (C) 2005-2006   Rodolfo Giometti <giometti@xxxxxxxx>
+ *
+ *   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 <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/time.h>
+#include <linux/timer.h>
+
+#include <linux/pps.h>
+
+/*
+ * Global variables
+ */
+
+static int source;
+static struct timer_list ktimer;
+
+/*
+ * The kernel timer
+ */
+
+static void pps_ktimer_event(unsigned long ptr)
+{
+	pr_info("PPS event at %lu\n", jiffies);
+
+	pps_event(source, PPS_CAPTUREASSERT, NULL);
+
+	mod_timer(&ktimer, jiffies + HZ);
+}
+
+/*
+ * The echo function
+ */
+
+static void pps_ktimer_echo(int source, int event, void *data)
+{
+	pr_info("echo %s %s for source %d\n",
+		event & PPS_CAPTUREASSERT ? "assert" : "",
+		event & PPS_CAPTURECLEAR ? "clear" : "",
+		source);
+}
+
+/*
+ * The PPS info struct
+ */
+
+static struct pps_source_info pps_ktimer_info = {
+	.name		= "ktimer",
+	.path		= "",
+	.mode		= PPS_CAPTUREASSERT | PPS_OFFSETASSERT | \
+			  PPS_ECHOASSERT | \
+			  PPS_CANWAIT | PPS_TSFMT_TSPEC,
+	.echo 		= pps_ktimer_echo,
+	.owner		= THIS_MODULE,
+};
+
+/*
+ * Module staff
+ */
+
+static void __exit pps_ktimer_exit(void)
+{
+	del_timer_sync(&ktimer);
+	pps_unregister_source(source);
+
+	pr_info("ktimer PPS source unregistered\n");
+}
+
+static int __init pps_ktimer_init(void)
+{
+	int ret;
+
+	ret = pps_register_source(&pps_ktimer_info,
+				PPS_CAPTUREASSERT | PPS_OFFSETASSERT);
+	if (ret < 0) {
+		printk(KERN_ERR "cannot register ktimer source\n");
+		return ret;
+	}
+	source = ret;
+
+	setup_timer(&ktimer, pps_ktimer_event, 0);
+	mod_timer(&ktimer, jiffies + HZ);
+
+	pr_info("ktimer PPS source registered at %d\n", source);
+
+	return  0;
+}
+
+module_init(pps_ktimer_init);
+module_exit(pps_ktimer_exit);
+
+MODULE_AUTHOR("Rodolfo Giometti <giometti@xxxxxxxx>");
+MODULE_DESCRIPTION("dummy PPS source by using a kernel timer (just for debug)");
+MODULE_LICENSE("GPL");
diff --git a/drivers/pps/kapi.c b/drivers/pps/kapi.c
new file mode 100644
index 0000000..8c9665e
--- /dev/null
+++ b/drivers/pps/kapi.c
@@ -0,0 +1,272 @@
+/*
+ * kapi.c -- kernel API
+ *
+ *
+ * Copyright (C) 2005-2007   Rodolfo Giometti <giometti@xxxxxxxx>
+ *
+ *   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 <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+#include <linux/spinlock.h>
+#include <linux/idr.h>
+#include <linux/fs.h>
+#include <linux/pps.h>
+
+/*
+ * Local variables
+ */
+
+static spinlock_t idr_lock = SPIN_LOCK_UNLOCKED;
+static DEFINE_IDR(pps_idr);
+
+/*
+ * Local functions
+ */
+
+static void pps_add_offset(struct pps_ktime *ts, struct pps_ktime *offset)
+{
+	ts->nsec += offset->nsec;
+	while (ts->nsec >= NSEC_PER_SEC) {
+		ts->nsec -= NSEC_PER_SEC;
+		ts->sec++;
+	}
+	while (ts->nsec < 0) {
+		ts->nsec += NSEC_PER_SEC;
+		ts->sec--;
+	}
+	ts->sec += offset->sec;
+}
+
+/*
+ * Exported functions
+ */
+
+int pps_register_source(struct pps_source_info *info, int default_params)
+{
+	struct pps_device *pps;
+	int id;
+	int err;
+
+	/* Sanity checks */
+	if ((info->mode & default_params) != default_params) {
+		printk(KERN_ERR "pps: %s: unsupported default parameters\n",
+					info->name);
+		err = -EINVAL;
+		goto pps_register_source_exit;
+	}
+	if ((info->mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) != 0 &&
+			info->echo == NULL) {
+		printk(KERN_ERR "pps: %s: echo function is not defined\n",
+					info->name);
+		err = -EINVAL;
+		goto pps_register_source_exit;
+	}
+	if ((info->mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
+		printk(KERN_ERR "pps: %s: unspecified time format\n",
+					info->name);
+		err = -EINVAL;
+		goto pps_register_source_exit;
+	}
+
+	/* Allocate memory for the new PPS source struct */
+	pps = kzalloc(sizeof(struct pps_device), GFP_KERNEL);
+	if (pps == NULL) {
+		err = -ENOMEM;
+		goto pps_register_source_exit;
+	}
+
+	/* Get new ID for the new PPS source */
+	if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) {
+		err = -ENOMEM;
+		goto kfree_pps;
+	}
+
+	spin_lock_irq(&idr_lock);
+	err = idr_get_new(&pps_idr, pps, &id);
+	spin_unlock_irq(&idr_lock);
+
+	if (err < 0)
+		goto kfree_pps;
+
+	id = id & MAX_ID_MASK;
+	if (id >= PPS_MAX_SOURCES) {
+		printk(KERN_ERR "pps: %s: too much PPS sources in the system\n",
+					info->name);
+		err = -EBUSY;
+		goto free_idr;
+	}
+
+	pps->id = id;
+	pps->params.api_version = PPS_API_VERS;
+	pps->params.mode = default_params;
+	pps->info = *info;
+
+	init_waitqueue_head(&pps->queue);
+	spin_lock_init(&pps->lock);
+	atomic_set(&pps->usage, 0);
+	init_waitqueue_head(&pps->usage_queue);
+
+	/* Create the char device */
+	err = pps_register_cdev(pps);
+	if (err < 0) {
+		printk(KERN_ERR "pps: %s: unable to create char device\n",
+					info->name);
+		goto free_idr;
+	}
+
+	/* Create the sysfs entry */
+	err = pps_sysfs_create_source_entry(pps);
+	if (err < 0) {
+		printk(KERN_ERR "pps: %s: unable to create sysfs entries\n",
+					info->name);
+		goto unregister_cdev;
+	}
+
+	pr_info("new PPS source %s at ID %d\n", info->name, id);
+
+	return id;
+
+unregister_cdev:
+	pps_unregister_cdev(pps);
+
+free_idr:
+	spin_lock_irq(&idr_lock);
+	idr_remove(&pps_idr, id);
+	spin_unlock_irq(&idr_lock);
+
+kfree_pps:
+	kfree(pps);
+
+pps_register_source_exit:
+	printk(KERN_ERR "pps: %s: unable to register source\n", info->name);
+
+	return err;
+}
+EXPORT_SYMBOL(pps_register_source);
+
+void pps_unregister_source(int source)
+{
+	struct pps_device *pps;
+
+	spin_lock_irq(&idr_lock);
+	pps = idr_find(&pps_idr, source);
+
+	if (!pps) {
+		spin_unlock_irq(&idr_lock);
+		return;
+	}
+
+	/* This should be done first in order to deny IRQ handlers
+	 * to access PPS structs
+	 */
+
+	idr_remove(&pps_idr, pps->id);
+	spin_unlock_irq(&idr_lock);
+
+	wait_event(pps->usage_queue, atomic_read(&pps->usage) == 0);
+
+	pps_sysfs_remove_source_entry(pps);
+	pps_unregister_cdev(pps);
+	kfree(pps);
+}
+EXPORT_SYMBOL(pps_unregister_source);
+
+void pps_event(int source, int event, void *data)
+{
+	struct pps_device *pps;
+	struct timespec __ts;
+	struct pps_ktime ts;
+	unsigned long flags;
+
+	/* First of all we get the time stamp... */
+	getnstimeofday(&__ts);
+
+	/* ... and translate it to PPS time data struct */
+	ts.sec = __ts.tv_sec;
+	ts.nsec = __ts.tv_nsec;
+
+	if ((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0) {
+		printk(KERN_ERR "pps: unknown event (%x) for source %d\n",
+			event, source);
+		return;
+	}
+
+	spin_lock_irqsave(&idr_lock, flags);
+	pps = idr_find(&pps_idr, source);
+
+	/* If we find a valid PPS source we lock it before leaving
+	 * the lock!
+	 */
+	if (pps)
+		atomic_inc(&pps->usage);
+	spin_unlock_irqrestore(&idr_lock, flags);
+
+	if (!pps)
+		return;
+
+	pr_debug("PPS event on source %d at at %llu.%06u\n",
+			pps->id, ts.sec, ts.nsec);
+
+	spin_lock_irqsave(&pps->lock, flags);
+
+	/* Must call the echo function? */
+	if ((pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)))
+		pps->info.echo(source, event, data);
+
+	/* Check the event */
+	pps->current_mode = pps->params.mode;
+	if (event & PPS_CAPTUREASSERT) {
+		/* We have to add an offset? */
+		if (pps->params.mode & PPS_OFFSETASSERT)
+			pps_add_offset(&ts, &pps->params.assert_off_tu);
+
+		/* Save the time stamp */
+		pps->assert_tu = ts;
+		pps->assert_sequence++;
+		pr_debug("capture assert seq #%u for source %d\n",
+			pps->assert_sequence, source);
+	}
+	if (event & PPS_CAPTURECLEAR) {
+		/* We have to add an offset? */
+		if (pps->params.mode & PPS_OFFSETCLEAR)
+			pps_add_offset(&ts, &pps->params.clear_off_tu);
+
+		/* Save the time stamp */
+		pps->clear_tu = ts;
+		pps->clear_sequence++;
+		pr_debug("capture clear seq #%u for source %d\n",
+			pps->clear_sequence, source);
+	}
+
+	pps->go = ~0;
+	wake_up_interruptible(&pps->queue);
+
+	kill_fasync(&pps->async_queue, SIGIO, POLL_IN);
+
+	spin_unlock_irqrestore(&pps->lock, flags);
+
+	/* Now we can release the PPS source for (possible) deregistration */
+	spin_lock_irqsave(&idr_lock, flags);
+	atomic_dec(&pps->usage);
+	wake_up_all(&pps->usage_queue);
+	spin_unlock_irqrestore(&idr_lock, flags);
+}
+EXPORT_SYMBOL(pps_event);
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
new file mode 100644
index 0000000..1e97f0e
--- /dev/null
+++ b/drivers/pps/pps.c
@@ -0,0 +1,331 @@
+/*
+ * pps.c -- Main PPS support file
+ *
+ *
+ * Copyright (C) 2005-2007   Rodolfo Giometti <giometti@xxxxxxxx>
+ *
+ *   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 <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <linux/cdev.h>
+#include <linux/poll.h>
+#include <linux/pps.h>
+
+/*
+ * Local variables
+ */
+
+static dev_t pps_devt;
+static struct class *pps_class;
+
+/*
+ * Char device methods
+ */
+
+static unsigned int pps_cdev_poll(struct file *file, poll_table *wait)
+{
+	struct pps_device *pps = file->private_data;
+
+	poll_wait(file, &pps->queue, wait);
+
+	return POLLIN | POLLRDNORM;
+}
+
+static int pps_cdev_fasync(int fd, struct file *file, int on)
+{
+	struct pps_device *pps = file->private_data;
+	return fasync_helper(fd, file, on, &pps->async_queue);
+}
+
+static int pps_cdev_ioctl(struct inode *inode, struct file *file,
+		unsigned int cmd, unsigned long arg)
+{
+	struct pps_device *pps = file->private_data;
+	struct pps_kparams params;
+	struct pps_fdata fdata;
+	unsigned long ticks;
+	void __user *uarg = (void __user *) arg;
+	int __user *iuarg = (int __user *) arg;
+	int err;
+
+	switch (cmd) {
+	case PPS_CHECK:
+
+		/* This does nothing but signal we are a PPS source... */
+
+		return 0;
+
+	case PPS_GETPARAMS:
+		pr_debug("PPS_GETPARAMS: source %d\n", pps->id);
+
+		/* Sanity checks */
+		if (!uarg)
+			return -EINVAL;
+
+		/* Return current parameters */
+		err = copy_to_user(uarg, &pps->params,
+						sizeof(struct pps_kparams));
+		if (err)
+			return -EFAULT;
+
+		break;
+
+	case PPS_SETPARAMS:
+		pr_debug("PPS_SETPARAMS: source %d\n", pps->id);
+
+		/* Check the capabilities */
+		if (!capable(CAP_SYS_TIME))
+			return -EPERM;
+
+		/* Sanity checks */
+		if (!uarg)
+			return -EINVAL;
+		err = copy_from_user(&params, uarg, sizeof(struct pps_kparams));
+		if (err)
+			return -EFAULT;
+		if (!(params.mode & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR))) {
+			pr_debug("capture mode unspecified (%x)\n",
+								params.mode);
+			return -EINVAL;
+		}
+
+		/* Check for supported capabilities */
+		if ((params.mode & ~pps->info.mode) != 0) {
+			pr_debug("unsupported capabilities (%x)\n",
+								params.mode);
+			return -EINVAL;
+		}
+
+		spin_lock_irq(&pps->lock);
+
+		/* Save the new parameters */
+		pps->params = params;
+
+		/* Restore the read only parameters */
+		if ((params.mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
+			/* section 3.3 of RFC 2783 interpreted */
+			pr_debug("time format unspecified (%x)\n",
+								params.mode);
+			pps->params.mode |= PPS_TSFMT_TSPEC;
+		}
+		if (pps->info.mode & PPS_CANWAIT)
+			pps->params.mode |= PPS_CANWAIT;
+		pps->params.api_version = PPS_API_VERS;
+
+		spin_unlock_irq(&pps->lock);
+
+		break;
+
+	case PPS_GETCAP:
+		pr_debug("PPS_GETCAP: source %d\n", pps->id);
+
+		/* Sanity checks */
+		if (!uarg)
+			return -EINVAL;
+
+		err = put_user(pps->info.mode, iuarg);
+		if (err)
+			return -EFAULT;
+
+		break;
+
+	case PPS_FETCH:
+		pr_debug("PPS_FETCH: source %d\n", pps->id);
+
+		if (!uarg)
+			return -EINVAL;
+		err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
+		if (err)
+			return -EFAULT;
+
+		pps->go = 0;
+
+		/* Manage the timeout */
+		if (fdata.timeout.flags & PPS_TIME_INVALID)
+			err = wait_event_interruptible(pps->queue, pps->go);
+		else {
+			pr_debug("timeout %lld.%09d\n",
+					fdata.timeout.sec, fdata.timeout.nsec);
+			ticks = fdata.timeout.sec * HZ;
+			ticks += fdata.timeout.nsec / (NSEC_PER_SEC / HZ);
+
+			if (ticks != 0) {
+				err = wait_event_interruptible_timeout(
+						pps->queue, pps->go, ticks);
+				if (err == 0)
+					return -ETIMEDOUT;
+			}
+		}
+
+		/* Check for pending signals */
+		if (err == -ERESTARTSYS) {
+			pr_debug("pending signal caught\n");
+			return -EINTR;
+		}
+
+		/* Return the fetched timestamp */
+		spin_lock_irq(&pps->lock);
+
+		fdata.info.assert_sequence = pps->assert_sequence;
+		fdata.info.clear_sequence = pps->clear_sequence;
+		fdata.info.assert_tu = pps->assert_tu;
+		fdata.info.clear_tu = pps->clear_tu;
+		fdata.info.current_mode = pps->current_mode;
+
+		spin_unlock_irq(&pps->lock);
+
+		err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
+		if (err)
+			return -EFAULT;
+
+		break;
+
+	default:
+		return -ENOTTY;
+		break;
+	}
+
+	return 0;
+}
+
+static int pps_cdev_open(struct inode *inode, struct file *file)
+{
+	struct pps_device *pps = container_of(inode->i_cdev,
+						struct pps_device, cdev);
+
+	/* Lock the PPS source against (possible) deregistration */
+	atomic_inc(&pps->usage);
+
+	file->private_data = pps;
+
+	return 0;
+}
+
+static int pps_cdev_release(struct inode *inode, struct file *file)
+{
+	struct pps_device *pps = file->private_data;
+
+	/* Free the PPS source and wake up (possible) deregistration */
+	atomic_dec(&pps->usage);
+	wake_up_all(&pps->usage_queue);
+
+	return 0;
+}
+
+/*
+ * Char device stuff
+ */
+
+static const struct file_operations pps_cdev_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.poll		= pps_cdev_poll,
+	.fasync		= pps_cdev_fasync,
+	.ioctl		= pps_cdev_ioctl,
+	.open		= pps_cdev_open,
+	.release	= pps_cdev_release,
+};
+
+int pps_register_cdev(struct pps_device *pps)
+{
+	int err;
+
+	pps->devno = MKDEV(MAJOR(pps_devt), pps->id);
+	cdev_init(&pps->cdev, &pps_cdev_fops);
+	pps->cdev.owner = pps->info.owner;
+
+	err = cdev_add(&pps->cdev, pps->devno, 1);
+	if (err) {
+		printk(KERN_ERR "pps: %s: failed to add char device %d:%d\n",
+				pps->info.name, MAJOR(pps_devt), pps->id);
+		return err;
+	}
+	pps->dev = device_create(pps_class, pps->info.dev, pps->devno,
+							"pps%d", pps->id);
+	if (err)
+		goto del_cdev;
+	dev_set_drvdata(pps->dev, pps);
+
+	pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
+			MAJOR(pps_devt), pps->id);
+
+	return 0;
+
+del_cdev:
+	cdev_del(&pps->cdev);
+
+	return err;
+}
+
+void pps_unregister_cdev(struct pps_device *pps)
+{
+	device_destroy(pps_class, pps->devno);
+	cdev_del(&pps->cdev);
+}
+
+/*
+ * Module staff
+ */
+
+static void __exit pps_exit(void)
+{
+	class_destroy(pps_class);
+
+	if (pps_devt)
+		unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
+
+	pr_info("LinuxPPS API ver. %d removed\n", PPS_API_VERS);
+}
+
+static int __init pps_init(void)
+{
+	int err;
+
+	pps_class = class_create(THIS_MODULE, "pps");
+	if (!pps_class) {
+		printk(KERN_ERR "pps: ailed to allocate class\n");
+		return -ENOMEM;
+	}
+
+	err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
+	if (err < 0) {
+		printk(KERN_ERR "pps: failed to allocate char device region\n");
+		goto remove_class;
+	}
+
+	pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
+	pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
+		"<giometti@xxxxxxxx>\n", PPS_VERSION);
+
+	return 0;
+
+remove_class:
+	class_destroy(pps_class);
+
+	return err;
+}
+
+subsys_initcall(pps_init);
+module_exit(pps_exit);
+
+MODULE_AUTHOR("Rodolfo Giometti <giometti@xxxxxxxx>");
+MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
+MODULE_LICENSE("GPL");
diff --git a/drivers/pps/sysfs.c b/drivers/pps/sysfs.c
new file mode 100644
index 0000000..9b65ddd
--- /dev/null
+++ b/drivers/pps/sysfs.c
@@ -0,0 +1,142 @@
+/*
+ * sysfs.c -- sysfs support
+ *
+ *
+ * Copyright (C) 2007   Rodolfo Giometti <giometti@xxxxxxxx>
+ *
+ *   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 <linux/device.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/pps.h>
+
+/*
+ * Attribute functions
+ */
+
+static ssize_t pps_show_assert(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct pps_device *pps = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%lld.%09d#%d\n",
+			pps->assert_tu.sec, pps->assert_tu.nsec,
+			pps->assert_sequence);
+}
+DEVICE_ATTR(assert, S_IRUGO, pps_show_assert, NULL);
+
+static ssize_t pps_show_clear(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct pps_device *pps = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%lld.%09d#%d\n",
+			pps->clear_tu.sec, pps->clear_tu.nsec,
+			pps->clear_sequence);
+}
+DEVICE_ATTR(clear, S_IRUGO, pps_show_clear, NULL);
+
+static ssize_t pps_show_mode(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct pps_device *pps = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%4x\n", pps->info.mode);
+}
+DEVICE_ATTR(mode, S_IRUGO, pps_show_mode, NULL);
+
+static ssize_t pps_show_echo(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct pps_device *pps = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", !!pps->info.echo);
+}
+DEVICE_ATTR(echo, S_IRUGO, pps_show_echo, NULL);
+
+static ssize_t pps_show_name(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct pps_device *pps = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%s\n", pps->info.name);
+}
+DEVICE_ATTR(name, S_IRUGO, pps_show_name, NULL);
+
+static ssize_t pps_show_path(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct pps_device *pps = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%s\n", pps->info.path);
+}
+DEVICE_ATTR(path, S_IRUGO, pps_show_path, NULL);
+
+/*
+ * Public functions
+ */
+
+void pps_sysfs_remove_source_entry(struct pps_device *pps)
+{
+	/* Delete info files */
+	if (pps->info.mode & PPS_CAPTUREASSERT)
+		device_remove_file(pps->dev, &dev_attr_assert);
+
+	if (pps->info.mode & PPS_CAPTURECLEAR)
+		device_remove_file(pps->dev, &dev_attr_clear);
+
+	device_remove_file(pps->dev, &dev_attr_mode);
+	device_remove_file(pps->dev, &dev_attr_echo);
+	device_remove_file(pps->dev, &dev_attr_name);
+	device_remove_file(pps->dev, &dev_attr_path);
+}
+
+int pps_sysfs_create_source_entry(struct pps_device *pps)
+{
+	int ret;
+
+	/* Create file "assert" and "clear" according to source capability */
+	if (pps->info.mode & PPS_CAPTUREASSERT) {
+		ret = device_create_file(pps->dev, &dev_attr_assert);
+		if (ret)
+			dev_err(pps->dev, "unable to create \"assert\" "
+					"sysfs entry");
+	}
+
+	if (pps->info.mode & PPS_CAPTURECLEAR) {
+		ret = device_create_file(pps->dev, &dev_attr_clear);
+		if (ret)
+			dev_err(pps->dev, "unable to create \"clear\" "
+					"sysfs entry");
+	}
+
+	ret = device_create_file(pps->dev, &dev_attr_mode);
+	if (ret)
+		dev_err(pps->dev, "unable to create \"mode\" sysfs entry");
+	ret = device_create_file(pps->dev, &dev_attr_echo);
+	if (ret)
+		dev_err(pps->dev, "unable to create \"echo\" sysfs entry");
+	ret = device_create_file(pps->dev, &dev_attr_name);
+	if (ret)
+		dev_err(pps->dev, "unable to create \"name\" sysfs entry");
+	ret = device_create_file(pps->dev, &dev_attr_path);
+	if (ret)
+		dev_err(pps->dev, "unable to create \"path\" sysfs entry");
+
+	return 0;
+}
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index f94109c..a5e83f8 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -2118,6 +2118,8 @@ serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
 		up->ier |= UART_IER_MSI;
 	if (up->capabilities & UART_CAP_UUE)
 		up->ier |= UART_IER_UUE | UART_IER_RTOIE;
+	if (up->port.flags & UPF_HARDPPS_CD)
+		up->ier |= UART_IER_MSI;	/* enable interrupts */
 
 	serial_out(up, UART_IER, up->ier);
 
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index a055f58..a40b87c 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -33,6 +33,7 @@
 #include <linux/serial.h> /* for serial_state and serial_icounter_struct */
 #include <linux/delay.h>
 #include <linux/mutex.h>
+#include <linux/pps.h>
 
 #include <asm/irq.h>
 #include <asm/uaccess.h>
@@ -633,6 +634,54 @@ static int uart_get_info(struct uart_state *state,
 	return 0;
 }
 
+#ifdef CONFIG_PPS_CLIENT_UART
+
+static int
+uart_register_pps_port(struct uart_state *state, struct uart_port *port)
+{
+	struct tty_driver *drv = port->info->tty->driver;
+	int ret;
+
+	state->pps_info.owner = THIS_MODULE;
+	state->pps_info.dev = port->dev;
+	snprintf(state->pps_info.name, PPS_MAX_NAME_LEN, "%s%d",
+		drv->driver_name, port->line);
+	snprintf(state->pps_info.path, PPS_MAX_NAME_LEN, "/dev/%s%d",
+		drv->name, port->line);
+
+	state->pps_info.mode = PPS_CAPTUREBOTH | \
+			PPS_OFFSETASSERT | PPS_OFFSETCLEAR | \
+			PPS_CANWAIT | PPS_TSFMT_TSPEC;
+
+	ret = pps_register_source(&state->pps_info, PPS_CAPTUREBOTH | \
+				PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
+	if (ret < 0) {
+		dev_err(port->dev, "cannot register PPS source \"%s\"\n",
+						state->pps_info.path);
+		return ret;
+	}
+	port->pps_source = ret;
+	dev_dbg(port->dev, "PPS source #%d \"%s\" added\n",
+		port->pps_source, state->pps_info.path);
+
+	return 0;
+}
+
+static void
+uart_unregister_pps_port(struct uart_state *state, struct uart_port *port)
+{
+	pps_unregister_source(port->pps_source);
+	dev_dbg(port->dev, "PPS source #%d \"%s\" removed\n",
+				port->pps_source, state->pps_info.path);
+}
+
+#else
+
+#define uart_register_pps_port(state, port)	do { } while (0)
+#define uart_unregister_pps_port(state, port)	do { } while (0)
+
+#endif /* CONFIG_PPS_CLIENT_UART */
+
 static int uart_set_info(struct uart_state *state,
 			 struct serial_struct __user *newinfo)
 {
@@ -807,11 +856,19 @@ static int uart_set_info(struct uart_state *state,
 			(port->flags & UPF_LOW_LATENCY) ? 1 : 0;
 
  check_and_exit:
+	/* PPS support enabled/disabled? */
+	if ((old_flags & UPF_HARDPPS_CD) != (new_flags & UPF_HARDPPS_CD)) {
+		if (new_flags & UPF_HARDPPS_CD)
+			uart_register_pps_port(state, port);
+		else
+			uart_unregister_pps_port(state, port);
+	}
+
 	retval = 0;
 	if (port->type == PORT_UNKNOWN)
 		goto exit;
 	if (state->info->flags & UIF_INITIALIZED) {
-		if (((old_flags ^ port->flags) & UPF_SPD_MASK) ||
+		if (((old_flags ^ port->flags) & (UPF_SPD_MASK|UPF_HARDPPS_CD)) ||
 		    old_custom_divisor != port->custom_divisor) {
 			/*
 			 * If they're setting up a custom divisor or speed,
@@ -2110,6 +2167,12 @@ uart_configure_port(struct uart_driver *drv, struct uart_state *state,
 		port->ops->config_port(port, flags);
 	}
 
+	/*
+	 * Add the PPS support for the current port.
+	 */
+	if (port->flags & UPF_HARDPPS_CD)
+		uart_register_pps_port(state, port);
+
 	if (port->type != PORT_UNKNOWN) {
 		unsigned long flags;
 
@@ -2359,6 +2422,12 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *port)
 	mutex_unlock(&state->mutex);
 
 	/*
+	 * Remove PPS support from the current port.
+	 */
+	if (port->flags & UPF_HARDPPS_CD)
+		uart_unregister_pps_port(state, port);
+
+	/*
 	 * Remove the devices from the tty layer
 	 */
 	tty_unregister_device(drv->tty_driver, port->line);
diff --git a/include/linux/Kbuild b/include/linux/Kbuild
index 818cc3a..0a9394f 100644
--- a/include/linux/Kbuild
+++ b/include/linux/Kbuild
@@ -295,6 +295,7 @@ unifdef-y += pmu.h
 unifdef-y += poll.h
 unifdef-y += ppp_defs.h
 unifdef-y += ppp-comp.h
+unifdef-y += pps.h
 unifdef-y += ptrace.h
 unifdef-y += qnx4_fs.h
 unifdef-y += quota.h
diff --git a/include/linux/parport.h b/include/linux/parport.h
index 9cdd694..549de6e 100644
--- a/include/linux/parport.h
+++ b/include/linux/parport.h
@@ -100,6 +100,7 @@ typedef enum {
 #include <linux/proc_fs.h>
 #include <linux/spinlock.h>
 #include <linux/wait.h>
+#include <linux/pps.h>
 #include <asm/system.h>
 #include <asm/ptrace.h>
 #include <asm/semaphore.h>
@@ -327,6 +328,11 @@ struct parport {
 
 	struct list_head full_list;
 	struct parport *slaves[3];
+
+#ifdef CONFIG_PPS_CLIENT_LP
+	struct pps_source_info pps_info;
+	int pps_source;		/* PPS source ID */
+#endif
 };
 
 #define DEFAULT_SPIN_TIME 500 /* us */
@@ -517,6 +523,12 @@ extern int parport_daisy_select (struct parport *port, int daisy, int mode);
 /* Lowlevel drivers _can_ call this support function to handle irqs.  */
 static __inline__ void parport_generic_irq(int irq, struct parport *port)
 {
+#ifdef CONFIG_PPS_CLIENT_LP
+	pps_event(port->pps_source, PPS_CAPTUREASSERT, port);
+	dev_dbg(port->dev, "PPS assert at %lu on source #%d\n",
+		jiffies, port->pps_source);
+#endif
+
 	parport_ieee1284_interrupt (irq, port);
 	read_lock(&port->cad_lock);
 	if (port->cad && port->cad->irq_func)
diff --git a/include/linux/pps.h b/include/linux/pps.h
new file mode 100644
index 0000000..1e742a6
--- /dev/null
+++ b/include/linux/pps.h
@@ -0,0 +1,196 @@
+/*
+ * pps.h -- PPS API kernel header.
+ *
+ *
+ * Copyright (C) 2005-2007   Rodolfo Giometti <giometti@xxxxxxxx>
+ *
+ *   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.
+ */
+
+
+#ifndef _PPS_H_
+#define _PPS_H_
+
+/* Implementation note: the logical states ``assert'' and ``clear''
+ * are implemented in terms of the chip register, i.e. ``assert''
+ * means the bit is set.  */
+
+/*
+ * 3.2 New data structures
+ */
+
+#ifndef __KERNEL__
+#include <linux/types.h>
+#include <sys/time.h>
+#include <sys/ioctl.h>
+#else
+#include <linux/time.h>
+#endif
+
+#define PPS_API_VERS		1
+#define PPS_MAX_NAME_LEN	32
+
+/* 32-bit vs. 64-bit compatibility.
+ *
+ * 0n i386, the alignment of a uint64_t is only 4 bytes, while on most other
+ * architectures it's 8 bytes. On i386, there will be no padding between the
+ * two consecutive 'struct pps_ktime' members of struct pps_kinfo and struct
+ * pps_kparams. But on most platforms there will be padding to ensure correct
+ * alignment.
+ *
+ * The simple fix is probably to add an explicit padding.
+ *					 		[David Woodhouse]
+ */
+struct pps_ktime {
+	__s64 sec;
+	__s32 nsec;
+	__u32 flags;
+};
+#define PPS_TIME_INVALID	(1<<0)	/* used to specify timeout==NULL */
+
+struct pps_kinfo {
+	__u32 assert_sequence;		/* seq. num. of assert event */
+	__u32 clear_sequence; 		/* seq. num. of clear event */
+	struct pps_ktime assert_tu;	/* time of assert event */
+	struct pps_ktime clear_tu;	/* time of clear event */
+	int current_mode;		/* current mode bits */
+};
+
+struct pps_kparams {
+	int api_version;		/* API version # */
+	int mode;			/* mode bits */
+	struct pps_ktime assert_off_tu;	/* offset compensation for assert */
+	struct pps_ktime clear_off_tu;	/* offset compensation for clear */
+};
+
+/*
+ * 3.3 Mode bit definitions
+ */
+
+/* Device/implementation parameters */
+#define PPS_CAPTUREASSERT	0x01	/* capture assert events */
+#define PPS_CAPTURECLEAR	0x02	/* capture clear events */
+#define PPS_CAPTUREBOTH		0x03	/* capture assert and clear events */
+
+#define PPS_OFFSETASSERT	0x10	/* apply compensation for assert ev. */
+#define PPS_OFFSETCLEAR		0x20	/* apply compensation for clear ev. */
+
+#define PPS_CANWAIT		0x100	/* can we wait for an event? */
+#define PPS_CANPOLL		0x200	/* bit reserved for future use */
+
+/* Kernel actions */
+#define PPS_ECHOASSERT		0x40	/* feed back assert event to output */
+#define PPS_ECHOCLEAR		0x80	/* feed back clear event to output */
+
+/* Timestamp formats */
+#define PPS_TSFMT_TSPEC		0x1000	/* select timespec format */
+#define PPS_TSFMT_NTPFP		0x2000	/* select NTP format */
+
+/*
+ * 3.4.4 New functions: disciplining the kernel timebase
+ */
+
+/* Kernel consumers */
+#define PPS_KC_HARDPPS		0	/* hardpps() (or equivalent) */
+#define PPS_KC_HARDPPS_PLL	1	/* hardpps() constrained to
+					   use a phase-locked loop */
+#define PPS_KC_HARDPPS_FLL	2	/* hardpps() constrained to
+					   use a frequency-locked loop */
+/*
+ * Here begins the implementation-specific part!
+ */
+
+struct pps_fdata {
+	struct pps_kinfo info;
+	struct pps_ktime timeout;
+};
+
+#include <linux/ioctl.h>
+
+#define PPS_CHECK		_IO('P', 0)
+#define PPS_GETPARAMS		_IOR('P', 1, struct pps_kparams *)
+#define PPS_SETPARAMS		_IOW('P', 2, struct pps_kparams *)
+#define PPS_GETCAP		_IOR('P', 3, int *)
+#define PPS_FETCH		_IOWR('P', 4, struct pps_fdata *)
+
+#ifdef __KERNEL__
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+
+#define PPS_VERSION		"5.0.0-rc3"
+#define PPS_MAX_SOURCES		16		/* should be enought... */
+
+/*
+ * Global defines
+ */
+
+/* The specific PPS source info */
+struct pps_source_info {
+	char name[PPS_MAX_NAME_LEN];		/* simbolic name */
+	char path[PPS_MAX_NAME_LEN];		/* path of connected device */
+	int mode;				/* PPS's allowed mode */
+
+	void (*echo)(int source, int event, void *data); /* PPS echo function */
+
+	struct module *owner;
+	struct device *dev;
+};
+
+/* The main struct */
+struct pps_device {
+	struct pps_source_info info;		/* PSS source info */
+
+	struct pps_kparams params;		/* PPS's current params */
+
+	__u32 assert_sequence;			/* PPS' assert event seq # */
+	__u32 clear_sequence;			/* PPS' clear event seq # */
+	struct pps_ktime assert_tu;
+	struct pps_ktime clear_tu;
+	int current_mode;			/* PPS mode at event time */
+
+	int go;					/* PPS event is arrived? */
+	wait_queue_head_t queue;		/* PPS event queue */
+
+	unsigned int id;			/* PPS source unique ID */
+	struct cdev cdev;
+	struct device *dev;
+	int devno;
+	struct fasync_struct *async_queue;	/* fasync method */
+	spinlock_t lock;
+
+	atomic_t usage;				/* usage count */
+	wait_queue_head_t usage_queue;
+
+	struct class class_dev;
+};
+
+/*
+ * Exported functions
+ */
+
+extern int pps_register_source(struct pps_source_info *info,
+				int default_params);
+extern void pps_unregister_source(int source);
+extern int pps_register_cdev(struct pps_device *pps);
+extern void pps_unregister_cdev(struct pps_device *pps);
+extern void pps_event(int source, int event, void *data);
+
+extern int pps_sysfs_create_source_entry(struct pps_device *pps);
+extern void pps_sysfs_remove_source_entry(struct pps_device *pps);
+
+#endif /* __KERNEL__ */
+
+#endif /* _PPS_H_ */
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 09d17b0..f9aefad 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -157,6 +157,7 @@
 #include <linux/tty.h>
 #include <linux/mutex.h>
 #include <linux/sysrq.h>
+#include <linux/pps.h>
 
 struct uart_port;
 struct uart_info;
@@ -236,6 +237,9 @@ struct uart_port {
 	unsigned char		regshift;		/* reg offset shift */
 	unsigned char		iotype;			/* io access style */
 	unsigned char		unused1;
+#ifdef CONFIG_PPS_CLIENT_UART
+	int			pps_source;		/* PPS source ID */
+#endif
 
 #define UPIO_PORT		(0)
 #define UPIO_HUB6		(1)
@@ -280,7 +284,8 @@ struct uart_port {
 #define UPF_IOREMAP		((__force upf_t) (1 << 31))
 
 #define UPF_CHANGE_MASK		((__force upf_t) (0x17fff))
-#define UPF_USR_MASK		((__force upf_t) (UPF_SPD_MASK|UPF_LOW_LATENCY))
+#define UPF_USR_MASK		((__force upf_t) (UPF_SPD_MASK|UPF_LOW_LATENCY\
+							|UPF_HARDPPS_CD))
 
 	unsigned int		mctrl;			/* current modem ctrl settings */
 	unsigned int		timeout;		/* character-based timeout */
@@ -312,6 +317,10 @@ struct uart_state {
 	struct uart_info	*info;
 	struct uart_port	*port;
 
+#ifdef CONFIG_PPS_CLIENT_UART
+	struct pps_source_info	pps_info;
+#endif
+
 	struct mutex		mutex;
 };
 
@@ -476,13 +485,22 @@ uart_handle_dcd_change(struct uart_port *port, unsigned int status)
 {
 	struct uart_info *info = port->info;
 
-	port->icount.dcd++;
-
-#ifdef CONFIG_HARD_PPS
-	if ((port->flags & UPF_HARDPPS_CD) && status)
-		hardpps();
+#ifdef CONFIG_PPS_CLIENT_UART
+	if (port->flags & UPF_HARDPPS_CD) {
+		if (status) {
+			pps_event(port->pps_source, PPS_CAPTUREASSERT, port);
+			dev_dbg(port->dev, "PPS assert at %lu on source #%d\n",
+				jiffies, port->pps_source);
+		} else {
+			pps_event(port->pps_source, PPS_CAPTURECLEAR, port);
+			dev_dbg(port->dev, "PPS clear at %lu on source #%d\n",
+				jiffies, port->pps_source);
+		}
+	}
 #endif
 
+	port->icount.dcd++;
+
 	if (info->flags & UIF_CHECK_CD) {
 		if (status)
 			wake_up_interruptible(&info->open_wait);