diff --git a/Documentation/pps/Makefile b/Documentation/pps/Makefile
new file mode 100644
index 0000000..3848aba
--- /dev/null
+++ b/Documentation/pps/Makefile
@@ -0,0 +1,27 @@
+TARGETS = ppstest
+
+CFLAGS += -Wall -O2 -D_GNU_SOURCE
+CFLAGS += -I . -I ../../include/
+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/ppsfind b/Documentation/pps/ppsfind
new file mode 100644
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..d911bf6
--- /dev/null
+++ b/Documentation/pps/ppstest.c
@@ -0,0 +1,149 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.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..d2628d2
--- /dev/null
+++ b/Documentation/pps/timepps.h
@@ -0,0 +1,198 @@
+/*
+ * timepps.h -- PPS API main header
+ *
+ * Copyright (C) 2005-2007   Rodolfo Giometti <giometti@linux.it>
+ *
+ *   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 <errno.h>
+#include <sys/time.h>
+#include <sys/ioctl.h>
+#include <linux/types.h>
+#include <linux/pps.h>
+
+#define LINUXPPS	1		/* signal we are using LinuxPPS */
+
+/*
+ * 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;
+	struct pps_kparams dummy;
+
+	if (!handle) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	/* First we check if current device is a valid PPS one by
+	 * doing a dummy PPS_GETPARAMS...
+	 */
+	ret = ioctl(source, PPS_GETPARAMS, &dummy);
+	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/Documentation/serial/tty.txt b/Documentation/serial/tty.txt
index 8e65c44..3fc812a 100644
--- a/Documentation/serial/tty.txt
+++ b/Documentation/serial/tty.txt
@@ -100,6 +100,10 @@ write_wakeup()	-	May be called at any point between open and close.
 			is permitted to call the driver write method from
 			this function. In such a situation defer it.
 
+dcd_change()	-	Report to the tty line the current DCD pin status
+			changes and the relative timestamp. The timestamp
+			can be NULL.
+
 
 Driver Access
 
diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index 3b09634..59f58d5 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -17,6 +17,7 @@
 #include <linux/delay.h>
 #include <linux/uaccess.h>
 #include <linux/percpu.h>
+#include <linux/pps_kernel.h>
 
 #include <asm/apic.h>
 
@@ -26,6 +27,11 @@ EXPORT_PER_CPU_SYMBOL(irq_stat);
 DEFINE_PER_CPU(struct pt_regs *, irq_regs);
 EXPORT_PER_CPU_SYMBOL(irq_regs);
 
+#ifdef CONFIG_PPS_IRQ_EVENTS
+struct timespec pps_irq_ts[NR_IRQS];
+EXPORT_SYMBOL(pps_irq_ts);
+#endif
+
 #ifdef CONFIG_DEBUG_STACKOVERFLOW
 /* Debugging check for stack overflow: is there less than 1KB free? */
 static int check_stack_overflow(void)
@@ -196,6 +202,12 @@ bool handle_irq(unsigned irq, struct pt_regs *regs)
 {
 	struct irq_desc *desc;
 	int overflow;
+#ifdef CONFIG_PPS_IRQ_EVENTS
+	struct timespec ts;
+
+	/* Get IRQ timestamps as soon as possible for the PPS layer */
+	getnstimeofday(&ts);
+#endif
 
 	overflow = check_stack_overflow();
 
@@ -203,6 +215,11 @@ bool handle_irq(unsigned irq, struct pt_regs *regs)
 	if (unlikely(!desc))
 		return false;
 
+#ifdef CONFIG_PPS_IRQ_EVENTS
+	/* Then, after sanity check, store the IRQ timestamp */
+	pps_irq_ts[irq] = ts;
+#endif
+
 	if (!execute_on_irq_stack(overflow, desc, irq)) {
 		if (unlikely(overflow))
 			print_stack_overflow();
diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index 977d8b4..10e6b4a 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -16,10 +16,16 @@
 #include <linux/ftrace.h>
 #include <linux/uaccess.h>
 #include <linux/smp.h>
+#include <linux/pps_kernel.h>
 #include <asm/io_apic.h>
 #include <asm/idle.h>
 #include <asm/apic.h>
 
+#ifdef CONFIG_PPS_IRQ_EVENTS
+struct timespec pps_irq_ts[NR_IRQS];
+EXPORT_SYMBOL(pps_irq_ts);
+#endif
+
 DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
 EXPORT_PER_CPU_SYMBOL(irq_stat);
 
@@ -51,6 +57,12 @@ static inline void stack_overflow_check(struct pt_regs *regs)
 bool handle_irq(unsigned irq, struct pt_regs *regs)
 {
 	struct irq_desc *desc;
+#ifdef CONFIG_PPS_IRQ_EVENTS
+	struct timespec ts;
+
+	/* Get IRQ timestamps as soon as possible for the PPS layer */
+	getnstimeofday(&ts);
+#endif
 
 	stack_overflow_check(regs);
 
@@ -58,6 +70,11 @@ bool handle_irq(unsigned irq, struct pt_regs *regs)
 	if (unlikely(!desc))
 		return false;
 
+#ifdef CONFIG_PPS_IRQ_EVENTS
+	/* Then, after sanity check, store the IRQ timestamp */
+	pps_irq_ts[irq] = ts;
+#endif
+
 	generic_handle_irq_desc(irq, desc);
 	return true;
 }
diff --git a/drivers/char/lp.c b/drivers/char/lp.c
index e444c2d..dca8a39 100644
--- a/drivers/char/lp.c
+++ b/drivers/char/lp.c
@@ -760,6 +760,27 @@ 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 };
@@ -831,6 +852,38 @@ 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 because port \"%s\" "
+					"is in polling mode\n",
+					port->pps_info.path);
+	}
+#endif
+
 	return 0;
 }
 
@@ -873,6 +926,14 @@ 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/char/n_tty.c b/drivers/char/n_tty.c
index 94a5d50..744bbe6 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -48,6 +48,7 @@
 #include <linux/audit.h>
 #include <linux/file.h>
 #include <linux/uaccess.h>
+#include <linux/module.h>
 
 #include <asm/system.h>
 
@@ -193,7 +194,7 @@ static void reset_buffer_flags(struct tty_struct *tty)
  *	Locking: ctrl_lock, read_lock.
  */
 
-static void n_tty_flush_buffer(struct tty_struct *tty)
+void n_tty_flush_buffer(struct tty_struct *tty)
 {
 	unsigned long flags;
 	/* clear everything and unthrottle the driver */
@@ -209,6 +210,7 @@ static void n_tty_flush_buffer(struct tty_struct *tty)
 	}
 	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 }
+EXPORT_SYMBOL_GPL(n_tty_flush_buffer);
 
 /**
  *	n_tty_chars_in_buffer	-	report available bytes
@@ -220,7 +222,7 @@ static void n_tty_flush_buffer(struct tty_struct *tty)
  *	Locking: read_lock
  */
 
-static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
+ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
 {
 	unsigned long flags;
 	ssize_t n = 0;
@@ -236,6 +238,7 @@ static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
 	spin_unlock_irqrestore(&tty->read_lock, flags);
 	return n;
 }
+EXPORT_SYMBOL_GPL(n_tty_chars_in_buffer);
 
 /**
  *	is_utf8_continuation	-	utf8 multibyte check
@@ -1329,7 +1332,7 @@ handle_newline:
  *	IO must be woken up
  */
 
-static void n_tty_write_wakeup(struct tty_struct *tty)
+void n_tty_write_wakeup(struct tty_struct *tty)
 {
 	/* Write out any echoed characters that are still pending */
 	process_echoes(tty);
@@ -1337,6 +1340,7 @@ static void n_tty_write_wakeup(struct tty_struct *tty)
 	if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
 		kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
 }
+EXPORT_SYMBOL_GPL(n_tty_write_wakeup);
 
 /**
  *	n_tty_receive_buf	-	data receive
@@ -1351,7 +1355,7 @@ static void n_tty_write_wakeup(struct tty_struct *tty)
  *	calls one at a time and in order (or using flush_to_ldisc)
  */
 
-static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
+void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 			      char *fp, int count)
 {
 	const unsigned char *p;
@@ -1425,6 +1429,7 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 	if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
 		tty_throttle(tty);
 }
+EXPORT_SYMBOL_GPL(n_tty_receive_buf);
 
 int is_ignored(int sig)
 {
@@ -1446,7 +1451,7 @@ int is_ignored(int sig)
  *	Locking: Caller holds tty->termios_mutex
  */
 
-static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
+void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
 {
 	int canon_change = 1;
 	BUG_ON(!tty);
@@ -1525,6 +1530,7 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
 	wake_up_interruptible(&tty->write_wait);
 	wake_up_interruptible(&tty->read_wait);
 }
+EXPORT_SYMBOL_GPL(n_tty_set_termios);
 
 /**
  *	n_tty_close		-	close the ldisc for this tty
@@ -1536,7 +1542,7 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
  *	ldisc methods are in progress.
  */
 
-static void n_tty_close(struct tty_struct *tty)
+void n_tty_close(struct tty_struct *tty)
 {
 	n_tty_flush_buffer(tty);
 	if (tty->read_buf) {
@@ -1548,6 +1554,7 @@ static void n_tty_close(struct tty_struct *tty)
 		tty->echo_buf = NULL;
 	}
 }
+EXPORT_SYMBOL_GPL(n_tty_close);
 
 /**
  *	n_tty_open		-	open an ldisc
@@ -1559,7 +1566,7 @@ static void n_tty_close(struct tty_struct *tty)
  *	until a close.
  */
 
-static int n_tty_open(struct tty_struct *tty)
+int n_tty_open(struct tty_struct *tty)
 {
 	if (!tty)
 		return -EINVAL;
@@ -1583,6 +1590,7 @@ static int n_tty_open(struct tty_struct *tty)
 	tty->closing = 0;
 	return 0;
 }
+EXPORT_SYMBOL_GPL(n_tty_open);
 
 static inline int input_available_p(struct tty_struct *tty, int amt)
 {
@@ -1697,7 +1705,7 @@ static int job_control(struct tty_struct *tty, struct file *file)
  *	This code must be sure never to sleep through a hangup.
  */
 
-static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
+ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
 			 unsigned char __user *buf, size_t nr)
 {
 	unsigned char __user *b = buf;
@@ -1897,6 +1905,7 @@ do_it_again:
 	n_tty_set_room(tty);
 	return retval;
 }
+EXPORT_SYMBOL_GPL(n_tty_read);
 
 /**
  *	n_tty_write		-	write function for tty
@@ -1920,7 +1929,7 @@ do_it_again:
  *		  lock themselves)
  */
 
-static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
+ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
 			   const unsigned char *buf, size_t nr)
 {
 	const unsigned char *b = buf;
@@ -1997,6 +2006,7 @@ break_out:
 		set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 	return (b - buf) ? b - buf : retval;
 }
+EXPORT_SYMBOL_GPL(n_tty_write);
 
 /**
  *	n_tty_poll		-	poll method for N_TTY
@@ -2012,7 +2022,7 @@ break_out:
  *	Called without the kernel lock held - fine
  */
 
-static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
+unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
 							poll_table *wait)
 {
 	unsigned int mask = 0;
@@ -2039,6 +2049,7 @@ static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
 		mask |= POLLOUT | POLLWRNORM;
 	return mask;
 }
+EXPORT_SYMBOL_GPL(n_tty_poll);
 
 static unsigned long inq_canon(struct tty_struct *tty)
 {
diff --git a/drivers/pps/Kconfig b/drivers/pps/Kconfig
index cc2eb8e..7c0b094 100644
--- a/drivers/pps/Kconfig
+++ b/drivers/pps/Kconfig
@@ -22,6 +22,18 @@ config PPS
 	  To compile this driver as a module, choose M here: the module
 	  will be called pps_core.ko.
 
+config PPS_IRQ_EVENTS
+	bool "Use low level IRQ timestamps"
+	depends on PPS && (X86_32 || X86_64)
+	default yes
+	help
+	  Say Y here if you wish using low level IRQ timestamps to register
+	  PPS events.
+
+	  This should improve PPS resolution but it delays echo functions
+	  call. Note also that this function is not implemented on all
+	  platforms and PPS clients!
+
 config PPS_DEBUG
 	bool "PPS debugging messages"
 	depends on PPS
@@ -30,4 +42,6 @@ config PPS_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
index 19ea582..98960dd 100644
--- a/drivers/pps/Makefile
+++ b/drivers/pps/Makefile
@@ -4,5 +4,6 @@
 
 pps_core-y			:= pps.o kapi.o sysfs.o
 obj-$(CONFIG_PPS)		:= pps_core.o
+obj-y				+= clients/
 
 ccflags-$(CONFIG_PPS_DEBUG) := -DDEBUG
diff --git a/drivers/pps/clients/Kconfig b/drivers/pps/clients/Kconfig
new file mode 100644
index 0000000..b4054cd
--- /dev/null
+++ b/drivers/pps/clients/Kconfig
@@ -0,0 +1,35 @@
+#
+# PPS clients configuration
+#
+
+if PPS
+
+comment "PPS clients support"
+
+config PPS_CLIENT_KTIMER
+	tristate "Kernel timer client (Testing client, use for debug)"
+	help
+	  If you say yes here you get support for a PPS debugging client
+	  which uses a kernel timer to generate the PPS signal.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called ktimer.ko.
+
+config PPS_CLIENT_LDISC
+	tristate "PPS line discipline"
+	depends on PPS
+	help
+	  If you say yes here you get support for a PPS source connected
+	  with the CD (Carrier Detect) pin of your serial port.
+
+comment "Parallel printer support (forced off)"
+	depends on !( PRINTER != n && !(PPS = m && PRINTER = y))
+
+config PPS_CLIENT_LP
+	bool "Parallel printer support"
+	depends on PRINTER != n && !(PPS = m && PRINTER = y)
+	help
+	  If you say yes here you get support for a PPS source connected
+	  with the interrupt pin of your parallel port.
+
+endif
diff --git a/drivers/pps/clients/Makefile b/drivers/pps/clients/Makefile
new file mode 100644
index 0000000..9f5b988
--- /dev/null
+++ b/drivers/pps/clients/Makefile
@@ -0,0 +1,10 @@
+#
+# Makefile for PPS clients.
+#
+
+obj-$(CONFIG_PPS_CLIENT_KTIMER)	+= ktimer.o
+obj-$(CONFIG_PPS_CLIENT_LDISC)	+= pps-ldisc.o
+
+ifeq ($(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..6de5dfc
--- /dev/null
+++ b/drivers/pps/clients/ktimer.c
@@ -0,0 +1,123 @@
+/*
+ * ktimer.c -- kernel timer test client
+ *
+ *
+ * Copyright (C) 2005-2006   Rodolfo Giometti <giometti@linux.it>
+ *
+ *   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_kernel.h>
+
+/*
+ * Global variables
+ */
+
+static int source;
+static struct timer_list ktimer;
+
+/*
+ * The kernel timer
+ */
+
+static void pps_ktimer_event(unsigned long ptr)
+{
+	struct timespec __ts;
+	struct pps_ktime ts;
+
+	/* First of all we get the time stamp... */
+	getnstimeofday(&__ts);
+
+	pr_info("PPS event at %lu\n", jiffies);
+
+	/* ... and translate it to PPS time data struct */
+	ts.sec = __ts.tv_sec;
+	ts.nsec = __ts.tv_nsec;
+
+	pps_event(source, &ts, 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@linux.it>");
+MODULE_DESCRIPTION("dummy PPS source by using a kernel timer (just for debug)");
+MODULE_LICENSE("GPL");
diff --git a/drivers/pps/clients/pps-ldisc.c b/drivers/pps/clients/pps-ldisc.c
new file mode 100644
index 0000000..f16396b
--- /dev/null
+++ b/drivers/pps/clients/pps-ldisc.c
@@ -0,0 +1,155 @@
+/*
+ * pps-ldisc.c -- PPS line discipline
+ *
+ *
+ * Copyright (C) 2008	Rodolfo Giometti <giometti@linux.it>
+ *
+ *   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/module.h>
+#include <linux/serial_core.h>
+#include <linux/tty.h>
+#include <linux/pps.h>
+
+#define PPS_TTY_MAGIC		0x0001
+
+static void pps_tty_dcd_change(struct tty_struct *tty, unsigned int status,
+				struct timespec *ts)
+{
+	long id = (long) tty->disc_data;
+	struct timespec __ts;
+	struct pps_ktime pps_ts;
+
+	/* First of all we get the time stamp... */
+	getnstimeofday(&__ts);
+
+	/* Does caller give us a timestamp? */
+	if (ts) {	/* Yes. Let's use it! */
+		pps_ts.sec = ts->tv_sec;
+		pps_ts.nsec = ts->tv_nsec;
+	} else {	/* No. Do it ourself! */
+		pps_ts.sec = __ts.tv_sec;
+		pps_ts.nsec = __ts.tv_nsec;
+	}
+
+	/* Now do the PPS event report */
+	pps_event(id, &pps_ts, status ? PPS_CAPTUREASSERT : PPS_CAPTURECLEAR,
+			NULL);
+
+	pr_debug("PPS %s at %lu on source #%d\n",
+			status ? "assert" : "clear", jiffies, (int) id);
+}
+
+static int pps_tty_open(struct tty_struct *tty)
+{
+	struct pps_source_info info;
+	struct tty_driver *drv = tty->driver;
+	int index = tty->index + drv->name_base;
+	long ret;
+
+	info.owner = THIS_MODULE;
+	info.dev = NULL;
+	snprintf(info.name, PPS_MAX_NAME_LEN, "%s%d", drv->driver_name, index);
+	snprintf(info.path, PPS_MAX_NAME_LEN, "/dev/%s%d", drv->name, index);
+	info.mode = PPS_CAPTUREBOTH | \
+			PPS_OFFSETASSERT | PPS_OFFSETCLEAR | \
+			PPS_CANWAIT | PPS_TSFMT_TSPEC;
+
+	ret = pps_register_source(&info, PPS_CAPTUREBOTH | \
+				PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
+	if (ret < 0) {
+		pr_err("cannot register PPS source \"%s\"\n", info.path);
+		return ret;
+	}
+	tty->disc_data = (void *) ret;
+
+	/* Should open N_TTY ldisc too */
+	ret = n_tty_open(tty);
+	if (ret < 0)
+		pps_unregister_source((long) tty->disc_data);
+
+	pr_info("PPS source #%d \"%s\" added\n", (int) ret, info.path);
+
+	return 0;
+}
+
+static void pps_tty_close(struct tty_struct *tty)
+{
+	long id = (long) tty->disc_data;
+
+	pps_unregister_source(id);
+	n_tty_close(tty);
+
+	pr_info("PPS source #%d removed\n", (int) id);
+}
+
+struct tty_ldisc_ops pps_ldisc_ops = {
+	.owner		= THIS_MODULE,
+	.magic		= PPS_TTY_MAGIC,
+	.name		= "pps_tty",
+	.dcd_change	= pps_tty_dcd_change,
+	.open		= pps_tty_open,
+	.close		= pps_tty_close,
+
+	/* Now we should use N_TTY ldisc methods in order to have
+	 * normal tty behaviour
+	 */
+	.flush_buffer	= n_tty_flush_buffer,
+	.chars_in_buffer = n_tty_chars_in_buffer,
+	.read		= n_tty_read,
+	.write		= n_tty_write,
+	.ioctl		= n_tty_ioctl_helper,
+	.set_termios	= n_tty_set_termios,
+	.poll		= n_tty_poll,
+	.receive_buf	= n_tty_receive_buf,
+	.write_wakeup	= n_tty_write_wakeup
+};
+
+/*
+ * Module stuff
+ */
+
+static int __init pps_tty_init(void)
+{
+	int err;
+
+	err = tty_register_ldisc(N_PPS, &pps_ldisc_ops);
+	if (err)
+		pr_err("can't register PPS line discipline\n");
+	else
+		pr_info("PPS line discipline registered\n");
+
+	return err;
+}
+
+static void __exit pps_tty_cleanup(void)
+{
+	int err;
+
+	err = tty_unregister_ldisc(N_PPS);
+	if (err)
+		pr_err("can't unregister PPS line discipline\n");
+	else
+		pr_info("PPS line discipline removed\n");
+}
+
+module_init(pps_tty_init);
+module_exit(pps_tty_cleanup);
+
+MODULE_ALIAS_LDISC(N_PPS);
+MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
+MODULE_DESCRIPTION("PPS TTY device driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index fb867a9..4d7d9b1 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -2411,6 +2411,18 @@ serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
 }
 
 static void
+serial8250_set_ldisc(struct uart_port *port)
+{
+	int line = port->line;
+
+	if (line >= port->info->port.tty->driver->num)
+		return;
+
+	if (port->info->port.tty->ldisc->ops->num == N_PPS)
+		serial8250_enable_ms(port);
+}
+
+static void
 serial8250_pm(struct uart_port *port, unsigned int state,
 	      unsigned int oldstate)
 {
@@ -2624,6 +2636,7 @@ static struct uart_ops serial8250_pops = {
 	.startup	= serial8250_startup,
 	.shutdown	= serial8250_shutdown,
 	.set_termios	= serial8250_set_termios,
+	.set_ldisc	= serial8250_set_ldisc,
 	.pm		= serial8250_pm,
 	.type		= serial8250_type,
 	.release_port	= serial8250_release_port,
diff --git a/include/linux/parport.h b/include/linux/parport.h
index 38a423e..ce508a9 100644
--- a/include/linux/parport.h
+++ b/include/linux/parport.h
@@ -98,6 +98,7 @@ typedef enum {
 #include <linux/proc_fs.h>
 #include <linux/spinlock.h>
 #include <linux/wait.h>
+#include <linux/pps_kernel.h>
 #include <linux/irqreturn.h>
 #include <linux/semaphore.h>
 #include <asm/system.h>
@@ -330,6 +331,11 @@ 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 */
@@ -518,6 +524,22 @@ 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(struct parport *port)
 {
+#ifdef CONFIG_PPS_CLIENT_LP
+	struct timespec __ts;
+	struct pps_ktime ts;
+
+	/* 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;
+
+	pps_event(port->pps_source, &ts, PPS_CAPTUREASSERT, port);
+	dev_dbg(port->dev, "PPS assert at %lu on source #%d\n",
+		jiffies, port->pps_source);
+#endif
+
 	parport_ieee1284_interrupt (port);
 	read_lock(&port->cad_lock);
 	if (port->cad && port->cad->irq_func)
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 23d2fb0..64d498e 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -184,6 +184,7 @@
 #include <linux/tty.h>
 #include <linux/mutex.h>
 #include <linux/sysrq.h>
+#include <linux/pps_kernel.h>
 
 struct uart_port;
 struct uart_info;
@@ -518,9 +519,17 @@ static inline void
 uart_handle_dcd_change(struct uart_port *port, unsigned int status)
 {
 	struct uart_info *info = port->info;
+	struct tty_ldisc *ld = tty_ldisc_ref(info->port.tty);
+	struct timespec ts;
+
+	if (ld && ld->ops->dcd_change)
+#ifdef CONFIG_PPS_IRQ_EVENTS
+		ts = pps_irq_ts[port->irq];
+#else
+		getnstimeofday(&ts);
+#endif
 
 	port->icount.dcd++;
-
 #ifdef CONFIG_HARD_PPS
 	if ((port->flags & UPF_HARDPPS_CD) && status)
 		hardpps();
@@ -532,6 +541,11 @@ uart_handle_dcd_change(struct uart_port *port, unsigned int status)
 		else if (info->port.tty)
 			tty_hangup(info->port.tty);
 	}
+
+	if (ld && ld->ops->dcd_change)
+		ld->ops->dcd_change(info->port.tty, status, &ts);
+	if (ld)
+		tty_ldisc_deref(ld);
 }
 
 /**
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 1488d8c..405750c 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -13,6 +13,7 @@
 #include <linux/tty_driver.h>
 #include <linux/tty_ldisc.h>
 #include <linux/mutex.h>
+#include <linux/poll.h>
 
 #include <asm/system.h>
 
@@ -467,6 +468,21 @@ extern void tty_ldisc_begin(void);
 /* This last one is just for the tty layer internals and shouldn't be used elsewhere */
 extern void tty_ldisc_enable(struct tty_struct *tty);
 
+extern void n_tty_flush_buffer(struct tty_struct *tty);
+extern ssize_t n_tty_chars_in_buffer(struct tty_struct *tty);
+extern void n_tty_write_wakeup(struct tty_struct *tty);
+extern void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
+			char *fp, int count);
+extern void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old);
+extern void n_tty_close(struct tty_struct *tty);
+extern int n_tty_open(struct tty_struct *tty);
+extern ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
+			unsigned char __user *buf, size_t nr);
+extern ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
+			const unsigned char *buf, size_t nr);
+extern unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
+			poll_table *wait);
+
 
 /* n_tty.c */
 extern struct tty_ldisc_ops tty_ldisc_N_TTY;
diff --git a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h
index 40f38d8..526fbf4 100644
--- a/include/linux/tty_ldisc.h
+++ b/include/linux/tty_ldisc.h
@@ -99,6 +99,12 @@
  *	cease I/O to the tty driver. Can sleep. The driver should
  *	seek to perform this action quickly but should wait until
  *	any pending driver I/O is completed.
+ *
+ * void (*dcd_change)(struct tty_struct *tty, unsigned int status,
+ * 			struct timespec *ts)
+ *
+ *	Tells the discipline that the DCD pin has changed its status and
+ *	the relative timestamp. Pointer ts can be NULL.
  */
 
 #include <linux/fs.h>
@@ -136,6 +142,8 @@ struct tty_ldisc_ops {
 	void	(*receive_buf)(struct tty_struct *, const unsigned char *cp,
 			       char *fp, int count);
 	void	(*write_wakeup)(struct tty_struct *);
+	void	(*dcd_change)(struct tty_struct *, unsigned int,
+				struct timespec *);
 
 	struct  module *owner;