[PATCH 1/9] LinuxPPS core support.

[PATCH 1/9] LinuxPPS core support.

[Rodolfo Giometti]

This patch adds the kernel side of the PPS support currently named
"LinuxPPS".

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.

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.

To obtain this goal the userland programs shoud use the PPS API
specification (RFC 2783 - Pulse-Per-Second API for UNIX-like Operating
Systems, Version 1.0) which in part is implemented by this patch. It
provides a set of chars devices, one per PPS source, which can be used
to get the time signal. The RFC's functions can be implemented by
accessing to these char devices.

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
---
 Documentation/ABI/testing/sysfs-pps |   73 ++++++++
 Documentation/ioctl-number.txt      |    2 +
 Documentation/pps/pps.txt           |  172 ++++++++++++++++++
 MAINTAINERS                         |    7 +
 drivers/Kconfig                     |    2 +
 drivers/Makefile                    |    1 +
 drivers/pps/Kconfig                 |   33 ++++
 drivers/pps/Makefile                |    8 +
 drivers/pps/kapi.c                  |  322 +++++++++++++++++++++++++++++++++
 drivers/pps/pps.c                   |  335 +++++++++++++++++++++++++++++++++++
 drivers/pps/sysfs.c                 |  104 +++++++++++
 include/linux/Kbuild                |    1 +
 include/linux/pps.h                 |  202 +++++++++++++++++++++
 13 files changed, 1262 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-pps
 create mode 100644 Documentation/pps/pps.txt
 create mode 100644 drivers/pps/Kconfig
 create mode 100644 drivers/pps/Makefile
 create mode 100644 drivers/pps/kapi.c
 create mode 100644 drivers/pps/pps.c
 create mode 100644 drivers/pps/sysfs.c
 create mode 100644 include/linux/pps.h

diff --git a/Documentation/ABI/testing/sysfs-pps b/Documentation/ABI/testing/sysfs-pps
new file mode 100644
index 0000000..8cba1d9
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-pps
@@ -0,0 +1,73 @@
+What:		/sys/class/pps/
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ directory will contain files and
+		directories that will provide a unified interface to
+		the PPS sources.
+
+What:		/sys/class/pps/ppsX/
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/ directory is related to X-th
+		PPS source into the system. Each directory will
+		contain files to manage and control its PPS source.
+
+What:		/sys/class/pps/ppsX/assert
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/assert file reports the assert events
+		and the assert sequence number of the X-th source in the form:
+
+			<secs>.<nsec>#<sequence>
+
+		If the source has no assert events the content of this file
+		is void.
+
+What:		/sys/class/pps/ppsX/clear
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/clear file reports the clear events
+		and the clear sequence number of the X-th source in the form:
+
+			<secs>.<nsec>#<sequence>
+
+		If the source has no clear events the content of this file
+		is void.
+
+What:		/sys/class/pps/ppsX/mode
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/mode file reports the functioning
+		mode of the X-th source in hexadecimal encoding.
+
+		Please, refer to linux/include/linux/pps.h for further
+		info.
+
+What:		/sys/class/pps/ppsX/echo
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/echo file reports if the X-th source
+		supports or not an "echo" function.
+
+What:		/sys/class/pps/ppsX/name
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/name file reports the name of the
+		X-th source.
+
+What:		/sys/class/pps/ppsX/path
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/path file reports the path name of
+		the device connected with the X-th source.
+
+		If the source is not connected with any device the content
+		of this file is void.
diff --git a/Documentation/ioctl-number.txt b/Documentation/ioctl-number.txt
index b880ce5..be021b5 100644
--- a/Documentation/ioctl-number.txt
+++ b/Documentation/ioctl-number.txt
@@ -147,6 +147,8 @@ Code	Seq#	Include File		Comments
 'p'	40-7F	linux/nvram.h
 'p'	80-9F				user-space parport
 					<mailto:tim@cyberelk.net>
+'p'	a0-a4	linux/pps.h		LinuxPPS
+					<mailto:giometti@linux.it>
 'q'	00-1F	linux/serio.h
 'q'	80-FF				Internet PhoneJACK, Internet LineJACK
 					<http://www.quicknet.net>
diff --git a/Documentation/pps/pps.txt b/Documentation/pps/pps.txt
new file mode 100644
index 0000000..c558ec3
--- /dev/null
+++ b/Documentation/pps/pps.txt
@@ -0,0 +1,172 @@
+
+			PPS - Pulse Per Second
+			----------------------
+
+(C) Copyright 2007 Rodolfo Giometti <giometti@enneenne.com>
+
+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 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, &ts, PPS_CAPTUREASSERT, ptr)
+
+where "ts" is the event's timestamp.
+
+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 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/MAINTAINERS b/MAINTAINERS
index d643e86..7fd676e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3376,6 +3376,13 @@ P:	James Chapman
 M:	jchapman@katalix.com
 S:	Maintained
 
+PPS SUPPORT
+P:	Rodolfo Giometti
+M:	giometti@enneenne.com
+W:	http://wiki.enneenne.com/index.php/LinuxPPS_support
+L:	linuxpps@ml.enneenne.com (subscribers-only)
+S:	Maintained
+
 PREEMPTIBLE KERNEL
 P:	Robert Love
 M:	rml@tech9.net
diff --git a/drivers/Kconfig b/drivers/Kconfig
index 2f557f5..4b679d2 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/gpio/Kconfig"
 
 source "drivers/w1/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
index fceb71a..da6329a 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -67,6 +67,7 @@ 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-$(CONFIG_HWMON)		+= hwmon/
diff --git a/drivers/pps/Kconfig b/drivers/pps/Kconfig
new file mode 100644
index 0000000..cc2eb8e
--- /dev/null
+++ b/drivers/pps/Kconfig
@@ -0,0 +1,33 @@
+#
+# PPS support configuration
+#
+
+menu "PPS support"
+
+config PPS
+	tristate "PPS support"
+	depends on EXPERIMENTAL
+	---help---
+	  PPS (Pulse Per Second) is a special pulse provided by some GPS
+	  antennae. Userland can use it to get a high-precision time
+	  reference.
+
+	  Some antennae's PPS signals are connected with the CD (Carrier
+	  Detect) pin of the serial line they use to communicate with the
+	  host. In this case use the SERIAL_LINE client support.
+
+	  Some antennae's PPS signals are connected with some special host
+	  inputs so you have to enable the corresponding client support.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pps_core.ko.
+
+config PPS_DEBUG
+	bool "PPS debugging messages"
+	depends on PPS
+	help
+	  Say Y here if you want the PPS support to produce a bunch of debug
+	  messages to the system log.  Select this if you are having a
+	  problem with PPS support and want to see more of what is going on.
+
+endmenu
diff --git a/drivers/pps/Makefile b/drivers/pps/Makefile
new file mode 100644
index 0000000..19ea582
--- /dev/null
+++ b/drivers/pps/Makefile
@@ -0,0 +1,8 @@
+#
+# Makefile for the PPS core.
+#
+
+pps_core-y			:= pps.o kapi.o sysfs.o
+obj-$(CONFIG_PPS)		:= pps_core.o
+
+ccflags-$(CONFIG_PPS_DEBUG) := -DDEBUG
diff --git a/drivers/pps/kapi.c b/drivers/pps/kapi.c
new file mode 100644
index 0000000..749ead7
--- /dev/null
+++ b/drivers/pps/kapi.c
@@ -0,0 +1,322 @@
+/*
+ * kapi.c -- kernel API
+ *
+ *
+ * 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.
+ */
+
+
+#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>
+
+/*
+ * Global variables
+ */
+
+DEFINE_SPINLOCK(pps_idr_lock);
+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
+ */
+
+/* pps_get_source - find a PPS source
+ *
+ * 	source: the PPS source ID.
+ *
+ * This function is used to find an already registered PPS source into the
+ * system.
+ *
+ * The function returns NULL if found nothing, otherwise it returns a pointer
+ * to the PPS source data struct (the refcounter is incremented by 1).
+ */
+
+struct pps_device *pps_get_source(int source)
+{
+	struct pps_device *pps;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pps_idr_lock, flags);
+
+	pps = idr_find(&pps_idr, source);
+	if (pps != NULL)
+		atomic_inc(&pps->usage);
+
+	spin_unlock_irqrestore(&pps_idr_lock, flags);
+
+	return pps;
+}
+
+/* pps_put_source - free the PPS source data
+ *
+ *	pps: a pointer to the PPS source.
+ *
+ * This function is used to free a PPS data struct if its refcount is 0.
+ */
+
+void pps_put_source(struct pps_device *pps)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&pps_idr_lock, flags);
+	BUG_ON(atomic_read(&pps->usage) == 0);
+
+	if (!atomic_dec_and_test(&pps->usage)) {
+		pps = NULL;
+		goto exit;
+	}
+
+	/* No more reference to the PPS source. We can safely remove the
+	 * PPS data struct.
+	 */
+	idr_remove(&pps_idr, pps->id);
+
+exit:
+	spin_unlock_irqrestore(&pps_idr_lock, flags);
+	kfree(pps);
+}
+
+/* pps_register_source - add a PPS source in the system
+ *
+ *	info: the PPS info struct
+ *	default_params: the default PPS parameters of the new source
+ *
+ * This function is used to add a new PPS source in the system. The new
+ * source is described by info's fields and it will have, as default PPS
+ * parameters, the ones specified into default_params.
+ *
+ * The function returns, in case of success, the PPS source ID.
+ */
+
+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(&pps_idr_lock);
+	err = idr_get_new(&pps_idr, pps, &id);
+	spin_unlock_irq(&pps_idr_lock);
+
+	if (err < 0)
+		goto kfree_pps;
+
+	id = id & MAX_ID_MASK;
+	if (id >= PPS_MAX_SOURCES) {
+		printk(KERN_ERR "pps: %s: too many 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, 1);
+
+	/* 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;
+	}
+
+	pr_info("new PPS source %s at ID %d\n", info->name, id);
+
+	return id;
+
+free_idr:
+	spin_lock_irq(&pps_idr_lock);
+	idr_remove(&pps_idr, id);
+	spin_unlock_irq(&pps_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);
+
+/* pps_unregister_source - remove a PPS source from the system
+ *
+ *	source: the PPS source ID
+ *
+ * This function is used to remove a previously registered PPS source from
+ * the system.
+ */
+
+void pps_unregister_source(int source)
+{
+	struct pps_device *pps;
+
+	spin_lock_irq(&pps_idr_lock);
+	pps = idr_find(&pps_idr, source);
+
+	if (!pps) {
+		BUG();
+		spin_unlock_irq(&pps_idr_lock);
+		return;
+	}
+	spin_unlock_irq(&pps_idr_lock);
+
+	pps_unregister_cdev(pps);
+	pps_put_source(pps);
+}
+EXPORT_SYMBOL(pps_unregister_source);
+
+/* pps_event - register a PPS event into the system
+ *
+ *	source: the PPS source ID
+ *	ts: the event timestamp
+ *	event: the event type
+ *	data: userdef pointer
+ *
+ * This function is used by each PPS client in order to register a new
+ * PPS event into the system (it's usually called inside an IRQ handler).
+ *
+ * If an echo function is associated with the PPS source it will be called
+ * as:
+ *	pps->info.echo(source, event, data);
+ */
+
+void pps_event(int source, struct pps_ktime *ts, int event, void *data)
+{
+	struct pps_device *pps;
+	unsigned long flags;
+
+	if ((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0) {
+		printk(KERN_ERR "pps: unknown event (%x) for source %d\n",
+			event, source);
+		return;
+	}
+
+	pps = pps_get_source(source);
+	if (!pps)
+		return;
+
+	pr_debug("PPS event on source %d at %llu.%06u\n",
+			pps->id, (unsigned long long) 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 */
+	pps_put_source(pps);
+}
+EXPORT_SYMBOL(pps_event);
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
new file mode 100644
index 0000000..ceff736
--- /dev/null
+++ b/drivers/pps/pps.c
@@ -0,0 +1,335 @@
+/*
+ * pps.c -- Main PPS support file
+ *
+ *
+ * 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.
+ */
+
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <linux/idr.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",
+					(long long) 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);
+	int found;
+
+	found = pps_get_source(pps->id) != 0;
+	if (!found)
+		return -ENODEV;
+
+	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 */
+	pps_put_source(pps);
+
+	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, NULL,
+							"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 stuff
+ */
+
+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: failed to allocate class\n");
+		return -ENOMEM;
+	}
+	pps_class->dev_attrs = pps_attrs;
+
+	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@linux.it>\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@linux.it>");
+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..99528a8
--- /dev/null
+++ b/drivers/pps/sysfs.c
@@ -0,0 +1,104 @@
+/*
+ * sysfs.c -- sysfs support
+ *
+ *
+ * Copyright (C) 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.
+ */
+
+
+#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);
+
+	if (!(pps->info.mode & PPS_CAPTUREASSERT))
+		return 0;
+
+	return sprintf(buf, "%lld.%09d#%d\n",
+			(long long) 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);
+
+	if (!(pps->info.mode & PPS_CAPTURECLEAR))
+		return 0;
+
+	return sprintf(buf, "%lld.%09d#%d\n",
+			(long long) 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);
+
+struct device_attribute pps_attrs[] = {
+	__ATTR(assert, S_IRUGO, pps_show_assert, NULL),
+	__ATTR(clear, S_IRUGO, pps_show_clear, NULL),
+	__ATTR(mode, S_IRUGO, pps_show_mode, NULL),
+	__ATTR(echo, S_IRUGO, pps_show_echo, NULL),
+	__ATTR(name, S_IRUGO, pps_show_name, NULL),
+	__ATTR(path, S_IRUGO, pps_show_path, NULL),
+	__ATTR_NULL,
+};
diff --git a/include/linux/Kbuild b/include/linux/Kbuild
index e531783..7f850e7 100644
--- a/include/linux/Kbuild
+++ b/include/linux/Kbuild
@@ -309,6 +309,7 @@ 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/pps.h b/include/linux/pps.h
new file mode 100644
index 0000000..b5c3cf9
--- /dev/null
+++ b/include/linux/pps.h
@@ -0,0 +1,202 @@
+/*
+ * pps.h -- PPS API kernel 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 _PPS_H_
+#define _PPS_H_
+
+#define PPS_VERSION		"5.3.3"
+#define PPS_MAX_SOURCES		16		/* should be enough... */
+
+/* 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		1
+#define PPS_API_VERS		PPS_API_VERS_1	/* we use API version 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', 0xa0)
+#define PPS_GETPARAMS		_IOR('p', 0xa1, struct pps_kparams *)
+#define PPS_SETPARAMS		_IOW('p', 0xa2, struct pps_kparams *)
+#define PPS_GETCAP		_IOR('p', 0xa3, int *)
+#define PPS_FETCH		_IOWR('p', 0xa4, struct pps_fdata *)
+
+#ifdef __KERNEL__
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+
+/*
+ * 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 */
+};
+
+/*
+ * Global variables
+ */
+
+extern spinlock_t pps_idr_lock;
+extern struct idr pps_idr;
+
+extern struct device_attribute pps_attrs[];
+
+/*
+ * Exported functions
+ */
+
+struct pps_device *pps_get_source(int source);
+extern void pps_put_source(struct pps_device *pps);
+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, struct pps_ktime *ts, int event, void *data);
+
+#endif /* __KERNEL__ */
+
+#endif /* _PPS_H_ */
-- 
1.5.4.3

Re: [PATCH 1/9] LinuxPPS core support.

[Michael Kerrisk]

Rodolfo,

Some fixes and comments below.

On Mon, Nov 24, 2008 at 11:00 AM, Rodolfo Giometti <giometti@linux.it> wrote:
> This patch adds the kernel side of the PPS support currently named
> "LinuxPPS".
>
> 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.
>
> 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.
>
> To obtain this goal the userland programs shoud use the PPS API
> specification (RFC 2783 - Pulse-Per-Second API for UNIX-like Operating
> Systems, Version 1.0) which in part is implemented by this patch. It
> provides a set of chars devices, one per PPS source, which can be used
> to get the time signal. The RFC's functions can be implemented by
> accessing to these char devices.
>
> Signed-off-by: Rodolfo Giometti <giometti@linux.it>
> ---
>  Documentation/ABI/testing/sysfs-pps |   73 ++++++++
>  Documentation/ioctl-number.txt      |    2 +
>  Documentation/pps/pps.txt           |  172 ++++++++++++++++++
>  MAINTAINERS                         |    7 +
>  drivers/Kconfig                     |    2 +
>  drivers/Makefile                    |    1 +
>  drivers/pps/Kconfig                 |   33 ++++
>  drivers/pps/Makefile                |    8 +
>  drivers/pps/kapi.c                  |  322 +++++++++++++++++++++++++++++++++
>  drivers/pps/pps.c                   |  335 +++++++++++++++++++++++++++++++++++
>  drivers/pps/sysfs.c                 |  104 +++++++++++
>  include/linux/Kbuild                |    1 +
>  include/linux/pps.h                 |  202 +++++++++++++++++++++
>  13 files changed, 1262 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-pps
>  create mode 100644 Documentation/pps/pps.txt
>  create mode 100644 drivers/pps/Kconfig
>  create mode 100644 drivers/pps/Makefile
>  create mode 100644 drivers/pps/kapi.c
>  create mode 100644 drivers/pps/pps.c
>  create mode 100644 drivers/pps/sysfs.c
>  create mode 100644 include/linux/pps.h
>
> diff --git a/Documentation/ABI/testing/sysfs-pps b/Documentation/ABI/testing/sysfs-pps
> new file mode 100644
> index 0000000..8cba1d9
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-pps
> @@ -0,0 +1,73 @@
> +What:          /sys/class/pps/
> +Date:          February 2008
> +Contact:       Rodolfo Giometti <giometti@linux.it>
> +Description:
> +               The /sys/class/pps/ directory will contain files and
> +               directories that will provide a unified interface to
> +               the PPS sources.
> +
> +What:          /sys/class/pps/ppsX/
> +Date:          February 2008
> +Contact:       Rodolfo Giometti <giometti@linux.it>
> +Description:
> +               The /sys/class/pps/ppsX/ directory is related to X-th
> +               PPS source into the system. Each directory will
> +               contain files to manage and control its PPS source.
> +
> +What:          /sys/class/pps/ppsX/assert
> +Date:          February 2008
> +Contact:       Rodolfo Giometti <giometti@linux.it>
> +Description:
> +               The /sys/class/pps/ppsX/assert file reports the assert events
> +               and the assert sequence number of the X-th source in the form:
> +
> +                       <secs>.<nsec>#<sequence>
> +
> +               If the source has no assert events the content of this file
> +               is void.

Does "the content of this file is void" mean "the file is empty".  If
so, the latter is clearer, IMO.

> +What:          /sys/class/pps/ppsX/clear
> +Date:          February 2008
> +Contact:       Rodolfo Giometti <giometti@linux.it>
> +Description:
> +               The /sys/class/pps/ppsX/clear file reports the clear events
> +               and the clear sequence number of the X-th source in the form:
> +
> +                       <secs>.<nsec>#<sequence>
> +
> +               If the source has no clear events the content of this file
> +               is void.

See comment above.

> +What:          /sys/class/pps/ppsX/mode
> +Date:          February 2008
> +Contact:       Rodolfo Giometti <giometti@linux.it>
> +Description:
> +               The /sys/class/pps/ppsX/mode file reports the functioning
> +               mode of the X-th source in hexadecimal encoding.
> +
> +               Please, refer to linux/include/linux/pps.h for further
> +               info.
> +
> +What:          /sys/class/pps/ppsX/echo
> +Date:          February 2008
> +Contact:       Rodolfo Giometti <giometti@linux.it>
> +Description:
> +               The /sys/class/pps/ppsX/echo file reports if the X-th source
> +               supports or not an "echo" function.

Better: "does or does not support an "echo" function"

> +
> +What:          /sys/class/pps/ppsX/name
> +Date:          February 2008
> +Contact:       Rodolfo Giometti <giometti@linux.it>
> +Description:
> +               The /sys/class/pps/ppsX/name file reports the name of the
> +               X-th source.
> +
> +What:          /sys/class/pps/ppsX/path
> +Date:          February 2008
> +Contact:       Rodolfo Giometti <giometti@linux.it>
> +Description:
> +               The /sys/class/pps/ppsX/path file reports the path name of
> +               the device connected with the X-th source.
> +
> +               If the source is not connected with any device the content
> +               of this file is void.

See my comment above.

> diff --git a/Documentation/ioctl-number.txt b/Documentation/ioctl-number.txt
> index b880ce5..be021b5 100644
> --- a/Documentation/ioctl-number.txt
> +++ b/Documentation/ioctl-number.txt
> @@ -147,6 +147,8 @@ Code        Seq#    Include File            Comments
>  'p'    40-7F   linux/nvram.h
>  'p'    80-9F                           user-space parport
>                                        <mailto:tim@cyberelk.net>
> +'p'    a0-a4   linux/pps.h             LinuxPPS
> +                                       <mailto:giometti@linux.it>
>  'q'    00-1F   linux/serio.h
>  'q'    80-FF                           Internet PhoneJACK, Internet LineJACK
>                                        <http://www.quicknet.net>
> diff --git a/Documentation/pps/pps.txt b/Documentation/pps/pps.txt
> new file mode 100644
> index 0000000..c558ec3
> --- /dev/null
> +++ b/Documentation/pps/pps.txt
> @@ -0,0 +1,172 @@
> +
> +                       PPS - Pulse Per Second
> +                       ----------------------
> +
> +(C) Copyright 2007 Rodolfo Giometti <giometti@enneenne.com>
> +
> +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.

"define into" is not correct English.  But I'm not sure what you do
mean to say here.

> +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

s/comes/arrives/
or
s/comes/occurs/

> +and record it for the userland.

"for 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.

Add a couple of commas here.

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

s/otherwise/and if not/

> +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:

s/follow/follows/

> +
> +    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,
> +    };
> +
> +and then calling the function pps_register_source() in your
> +intialization routine as follow:

s/follow/follows/

> +    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

s/is/it is/

> +must be a subset of ones defined into the struct

"defined into" is not English -- do you mean "defined in"

> +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, &ts, PPS_CAPTUREASSERT, ptr)
> +
> +where "ts" is the event's timestamp.
> +
> +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 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

Before the "#" is the timestamp in seconds; 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/MAINTAINERS b/MAINTAINERS
> index d643e86..7fd676e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3376,6 +3376,13 @@ P:       James Chapman
>  M:     jchapman@katalix.com
>  S:     Maintained
>
> +PPS SUPPORT
> +P:     Rodolfo Giometti
> +M:     giometti@enneenne.com
> +W:     http://wiki.enneenne.com/index.php/LinuxPPS_support
> +L:     linuxpps@ml.enneenne.com (subscribers-only)
> +S:     Maintained
> +
>  PREEMPTIBLE KERNEL
>  P:     Robert Love
>  M:     rml@tech9.net
> diff --git a/drivers/Kconfig b/drivers/Kconfig
> index 2f557f5..4b679d2 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/gpio/Kconfig"
>
>  source "drivers/w1/Kconfig"
> diff --git a/drivers/Makefile b/drivers/Makefile
> index fceb71a..da6329a 100644
> --- a/drivers/Makefile
> +++ b/drivers/Makefile
> @@ -67,6 +67,7 @@ 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/pps/Kconfig b/drivers/pps/Kconfig
> new file mode 100644
> index 0000000..cc2eb8e
> --- /dev/null
> +++ b/drivers/pps/Kconfig
> @@ -0,0 +1,33 @@
> +#
> +# 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 a high-precision time

Antennas is I believe the more common English plural.

> +         reference.
> +
> +         Some antennae's PPS signals are connected with the CD (Carrier

Antennas'

> +         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

Antennas'

> +         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.

Cheers,

Michael

-- 
Michael Kerrisk Linux man-pages maintainer;
http://www.kernel.org/doc/man-pages/ Found a documentation bug?
http://www.kernel.org/doc/man-pages/reporting_bugs.html

Re: [PATCH 1/9] LinuxPPS core support.

[Rodolfo Giometti]

Thanks for your suggestions! I'm going to fix them ASAP.

On Tue, Nov 25, 2008 at 11:24:57AM -0500, Michael Kerrisk wrote:
> 
> Antennas is I believe the more common English plural.

In the past I got a suggestion in using «antennae» instead of
«antennas»... do you think I can leave it anyway? :)

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail: giometti@enneenne.com
Linux Device Driver                          giometti@linux.it
Embedded Systems                     phone:  +39 349 2432127
UNIX programming                     skype:  rodolfo.giometti

Re: [PATCH 1/9] LinuxPPS core support.

[Michael Kerrisk]

On Tue, Nov 25, 2008 at 11:45 AM, Rodolfo Giometti
<giometti@enneenne.com> wrote:
> Thanks for your suggestions! I'm going to fix them ASAP.
>
> On Tue, Nov 25, 2008 at 11:24:57AM -0500, Michael Kerrisk wrote:
>>
>> Antennas is I believe the more common English plural.
>
> In the past I got a suggestion in using «antennae» instead of
> «antennas»... do you think I can leave it anyway? :)

Take a look at this thread:

http://forum.wordreference.com/showthread.php?t=93958

and

this article:

http://en.wikipedia.org/wiki/Antenna_(radio)

Weight of usage seems to be "antennas" when we are talking about radio devices.

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
git://git.kernel.org/pub/scm/docs/man-pages/man-pages.git
man-pages online: http://www.kernel.org/doc/man-pages/online_pages.html
Found a bug? http://www.kernel.org/doc/man-pages/reporting_bugs.html

Re: [PATCH 1/9] LinuxPPS core support.

[H. Peter Anvin]

Michael Kerrisk wrote:
> 
> Weight of usage seems to be "antennas" when we are talking about radio devices.
> 

"antennas" in American English, "aerials" in British English ;)

	-hpa

Re: [PATCH 1/9] LinuxPPS core support.

[Alan Cox]

On Tue, 25 Nov 2008 17:45:12 +0100
Rodolfo Giometti <giometti@enneenne.com> wrote:

> Thanks for your suggestions! I'm going to fix them ASAP.
> 
> On Tue, Nov 25, 2008 at 11:24:57AM -0500, Michael Kerrisk wrote:
> > 
> > Antennas is I believe the more common English plural.
> 
> In the past I got a suggestion in using «antennae» instead of
> «antennas»... do you think I can leave it anyway? :)

The Oxford English Dictionary says both are correct. Antennae is to me
the more scholarly/educated spelling (or depending upon your point of view
another pointless example of academic absurdity and dedication to dead
languages)

Alan

Re: [PATCH 1/9] LinuxPPS core support.

[David Woodhouse]

On Tue, 2008-11-25 at 17:45 +0100, Rodolfo Giometti wrote:
> Thanks for your suggestions! I'm going to fix them ASAP.
> 
> On Tue, Nov 25, 2008 at 11:24:57AM -0500, Michael Kerrisk wrote:
> > 
> > Antennas is I believe the more common English plural.
> 
> In the past I got a suggestion in using «antennae» instead of
> «antennas»... do you think I can leave it anyway? :)

Antennae is correct.

-- 
dwmw2

Re: [PATCH 1/9] LinuxPPS core support.

[David Woodhouse]

On Tue, 2008-11-25 at 17:07 +0000, Alan Cox wrote:
> On Tue, 25 Nov 2008 17:45:12 +0100
> Rodolfo Giometti <giometti@enneenne.com> wrote:
> 
> > Thanks for your suggestions! I'm going to fix them ASAP.
> > 
> > On Tue, Nov 25, 2008 at 11:24:57AM -0500, Michael Kerrisk wrote:
> > > 
> > > Antennas is I believe the more common English plural.
> > 
> > In the past I got a suggestion in using «antennae» instead of
> > «antennas»... do you think I can leave it anyway? :)
> 
> The Oxford English Dictionary says both are correct. Antennae is to me
> the more scholarly/educated spelling (or depending upon your point of view
> another pointless example of academic absurdity and dedication to dead
> languages)

ur rite m8.

-- 
dwmw2

Re: [PATCH 1/9] LinuxPPS core support.

[Theodore Tso]

On Tue, Nov 25, 2008 at 05:07:02PM +0000, Alan Cox wrote:
> 
> The Oxford English Dictionary says both are correct. Antennae is to me
> the more scholarly/educated spelling (or depending upon your point of view
> another pointless example of academic absurdity and dedication to dead
> languages)

Linux venit et vicit!  :-)

						- Ted

LinuxPPS (Version 10): the PPS Linux implementation.

[Rodolfo Giometti]

Note: Very few changes since last post! Please, add this patch set
      into next available merge window.

This patch set adds the PPS support into Linux.

PPS means "pulse per second" and its API is specified by RFC 2783
(Pulse-Per-Second API for UNIX-like Operating Systems, Version 1.0).

The code has been tested with the NTPD program
(http://www.eecis.udel.edu/~mills/ntp/html/index.html) and several GPS
antennae.


Changelog
=========

Version 9 -> 10:
---------------

* Fixes for 2.6.28-rc6

Version 8 -> 9:
---------------

* language fix up.

Version 7 -> 8:
---------------

* PPS ldisc module locking fix up.

* race during ldisc initialization fix up.

Version 6 -> 7:
---------------

* A new line discipline has been added in order to leave untouched
  the serial ports code (as suggested by Alan).

* n_tty.c exports only GPL symbols.

* ioctl numbers fixed in order to avoid any conflicts.

Note: Last patch (0009-PPS-low-level-IRQ-timestamps-recording.patch)
      implements low level IRQs timestamps recording which improves
      PPS precision but can be dropped for kernel inclusion! As
      suggested by Alan: "After that is sorted/merged we can come back
      to working out the best way to improve the IRQ and HARDPPS
      hacks."

Rodolfo

--

 b/Documentation/ABI/testing/sysfs-pps  |   73 +++++++
 b/Documentation/ioctl/ioctl-number.txt |    2
 b/Documentation/pps/Makefile           |   28 ++
 b/Documentation/pps/pps.txt            |  172 ++++++++++++++++
 b/Documentation/pps/ppsfind            |   17 +
 b/Documentation/pps/ppsldisc.c         |   46 ++++
 b/Documentation/pps/ppstest.c          |  151 ++++++++++++++
 b/Documentation/pps/timepps.h          |  195 +++++++++++++++++++
 b/Documentation/serial/tty.txt         |    4
 b/MAINTAINERS                          |    7
 b/arch/x86/kernel/irq_32.c             |   16 +
 b/arch/x86/kernel/irq_64.c             |   21 +-
 b/drivers/Kconfig                      |    2
 b/drivers/Makefile                     |    1
 b/drivers/char/lp.c                    |   61 ++++++
 b/drivers/char/n_tty.c                 |   32 ++-
 b/drivers/pps/Kconfig                  |   33 +++
 b/drivers/pps/Makefile                 |    8
 b/drivers/pps/clients/Kconfig          |   18 +
 b/drivers/pps/clients/Makefile         |    9
 b/drivers/pps/clients/ktimer.c         |  124 ++++++++++++
 b/drivers/pps/clients/pps-ldisc.c      |  155 +++++++++++++++
 b/drivers/pps/kapi.c                   |  322 +++++++++++++++++++++++++++++++
 b/drivers/pps/pps.c                    |  335 +++++++++++++++++++++++++++++++++
 b/drivers/pps/sysfs.c                  |  104 ++++++++++
 b/drivers/serial/8250.c                |   13 +
 b/include/linux/Kbuild                 |    1
 b/include/linux/parport.h              |   22 ++
 b/include/linux/pps.h                  |  202 +++++++++++++++++++
 b/include/linux/serial_core.h          |   11 -
 b/include/linux/tty.h                  |   16 +
 b/include/linux/tty_ldisc.h            |    8
 drivers/pps/Kconfig                    |   14 +
 drivers/pps/Makefile                   |    1
 drivers/pps/clients/Kconfig            |   17 +
 drivers/pps/clients/Makefile           |    1
 include/linux/pps.h                    |    1
 include/linux/serial_core.h            |    7
 38 files changed, 2235 insertions(+), 15 deletions(-)

[PATCH 1/9] LinuxPPS core support.

[Rodolfo Giometti]

This patch adds the kernel side of the PPS support currently named
"LinuxPPS".

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.

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.

To obtain this goal the userland programs shoud use the PPS API
specification (RFC 2783 - Pulse-Per-Second API for UNIX-like Operating
Systems, Version 1.0) which in part is implemented by this patch. It
provides a set of chars devices, one per PPS source, which can be used
to get the time signal. The RFC's functions can be implemented by
accessing to these char devices.

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
---
 Documentation/ABI/testing/sysfs-pps  |   73 ++++++++
 Documentation/ioctl/ioctl-number.txt |    2 +
 Documentation/pps/pps.txt            |  172 +++++++++++++++++
 MAINTAINERS                          |    7 +
 drivers/Kconfig                      |    2 +
 drivers/Makefile                     |    1 +
 drivers/pps/Kconfig                  |   33 ++++
 drivers/pps/Makefile                 |    8 +
 drivers/pps/kapi.c                   |  322 ++++++++++++++++++++++++++++++++
 drivers/pps/pps.c                    |  335 ++++++++++++++++++++++++++++++++++
 drivers/pps/sysfs.c                  |  104 +++++++++++
 include/linux/Kbuild                 |    1 +
 include/linux/pps.h                  |  202 ++++++++++++++++++++
 13 files changed, 1262 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-pps
 create mode 100644 Documentation/pps/pps.txt
 create mode 100644 drivers/pps/Kconfig
 create mode 100644 drivers/pps/Makefile
 create mode 100644 drivers/pps/kapi.c
 create mode 100644 drivers/pps/pps.c
 create mode 100644 drivers/pps/sysfs.c
 create mode 100644 include/linux/pps.h

diff --git a/Documentation/ABI/testing/sysfs-pps b/Documentation/ABI/testing/sysfs-pps
new file mode 100644
index 0000000..25028c7
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-pps
@@ -0,0 +1,73 @@
+What:		/sys/class/pps/
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ directory will contain files and
+		directories that will provide a unified interface to
+		the PPS sources.
+
+What:		/sys/class/pps/ppsX/
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/ directory is related to X-th
+		PPS source into the system. Each directory will
+		contain files to manage and control its PPS source.
+
+What:		/sys/class/pps/ppsX/assert
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/assert file reports the assert events
+		and the assert sequence number of the X-th source in the form:
+
+			<secs>.<nsec>#<sequence>
+
+		If the source has no assert events the content of this file
+		is empty.
+
+What:		/sys/class/pps/ppsX/clear
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/clear file reports the clear events
+		and the clear sequence number of the X-th source in the form:
+
+			<secs>.<nsec>#<sequence>
+
+		If the source has no clear events the content of this file
+		is empty.
+
+What:		/sys/class/pps/ppsX/mode
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/mode file reports the functioning
+		mode of the X-th source in hexadecimal encoding.
+
+		Please, refer to linux/include/linux/pps.h for further
+		info.
+
+What:		/sys/class/pps/ppsX/echo
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/echo file reports if the X-th does
+		or does not support an "echo" function.
+
+What:		/sys/class/pps/ppsX/name
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/name file reports the name of the
+		X-th source.
+
+What:		/sys/class/pps/ppsX/path
+Date:		February 2008
+Contact:	Rodolfo Giometti <giometti@linux.it>
+Description:
+		The /sys/class/pps/ppsX/path file reports the path name of
+		the device connected with the X-th source.
+
+		If the source is not connected with any device the content
+		of this file is empty.
diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
index b880ce5..be021b5 100644
--- a/Documentation/ioctl/ioctl-number.txt
+++ b/Documentation/ioctl/ioctl-number.txt
@@ -147,6 +147,8 @@ Code	Seq#	Include File		Comments
 'p'	40-7F	linux/nvram.h
 'p'	80-9F				user-space parport
 					<mailto:tim@cyberelk.net>
+'p'	a0-a4	linux/pps.h		LinuxPPS
+					<mailto:giometti@linux.it>
 'q'	00-1F	linux/serio.h
 'q'	80-FF				Internet PhoneJACK, Internet LineJACK
 					<http://www.quicknet.net>
diff --git a/Documentation/pps/pps.txt b/Documentation/pps/pps.txt
new file mode 100644
index 0000000..125f4ab
--- /dev/null
+++ b/Documentation/pps/pps.txt
@@ -0,0 +1,172 @@
+
+			PPS - Pulse Per Second
+			----------------------
+
+(C) Copyright 2007 Rodolfo Giometti <giometti@enneenne.com>
+
+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 in 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 arrives the system must apply to it a timestamp
+and record it for 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, and if not 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 follows:
+
+    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,
+    };
+
+and then calling the function pps_register_source() in your
+intialization routine as follows:
+
+    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 (it is obvious that these parameters
+must be a subset of ones defined in 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, &ts, PPS_CAPTUREASSERT, ptr)
+
+where "ts" is the event's timestamp.
+
+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 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 in 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; 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/MAINTAINERS b/MAINTAINERS
index 618c1ef..01d6667 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3421,6 +3421,13 @@ P:	James Chapman
 M:	jchapman@katalix.com
 S:	Maintained
 
+PPS SUPPORT
+P:	Rodolfo Giometti
+M:	giometti@enneenne.com
+W:	http://wiki.enneenne.com/index.php/LinuxPPS_support
+L:	linuxpps@ml.enneenne.com (subscribers-only)
+S:	Maintained
+
 PREEMPTIBLE KERNEL
 P:	Robert Love
 M:	rml@tech9.net
diff --git a/drivers/Kconfig b/drivers/Kconfig
index 2f557f5..4b679d2 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/gpio/Kconfig"
 
 source "drivers/w1/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
index fceb71a..da6329a 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -67,6 +67,7 @@ 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-$(CONFIG_HWMON)		+= hwmon/
diff --git a/drivers/pps/Kconfig b/drivers/pps/Kconfig
new file mode 100644
index 0000000..cc2eb8e
--- /dev/null
+++ b/drivers/pps/Kconfig
@@ -0,0 +1,33 @@
+#
+# PPS support configuration
+#
+
+menu "PPS support"
+
+config PPS
+	tristate "PPS support"
+	depends on EXPERIMENTAL
+	---help---
+	  PPS (Pulse Per Second) is a special pulse provided by some GPS
+	  antennae. Userland can use it to get a high-precision time
+	  reference.
+
+	  Some antennae's PPS signals are connected with the CD (Carrier
+	  Detect) pin of the serial line they use to communicate with the
+	  host. In this case use the SERIAL_LINE client support.
+
+	  Some antennae's PPS signals are connected with some special host
+	  inputs so you have to enable the corresponding client support.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pps_core.ko.
+
+config PPS_DEBUG
+	bool "PPS debugging messages"
+	depends on PPS
+	help
+	  Say Y here if you want the PPS support to produce a bunch of debug
+	  messages to the system log.  Select this if you are having a
+	  problem with PPS support and want to see more of what is going on.
+
+endmenu
diff --git a/drivers/pps/Makefile b/drivers/pps/Makefile
new file mode 100644
index 0000000..19ea582
--- /dev/null
+++ b/drivers/pps/Makefile
@@ -0,0 +1,8 @@
+#
+# Makefile for the PPS core.
+#
+
+pps_core-y			:= pps.o kapi.o sysfs.o
+obj-$(CONFIG_PPS)		:= pps_core.o
+
+ccflags-$(CONFIG_PPS_DEBUG) := -DDEBUG
diff --git a/drivers/pps/kapi.c b/drivers/pps/kapi.c
new file mode 100644
index 0000000..749ead7
--- /dev/null
+++ b/drivers/pps/kapi.c
@@ -0,0 +1,322 @@
+/*
+ * kapi.c -- kernel API
+ *
+ *
+ * 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.
+ */
+
+
+#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>
+
+/*
+ * Global variables
+ */
+
+DEFINE_SPINLOCK(pps_idr_lock);
+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
+ */
+
+/* pps_get_source - find a PPS source
+ *
+ * 	source: the PPS source ID.
+ *
+ * This function is used to find an already registered PPS source into the
+ * system.
+ *
+ * The function returns NULL if found nothing, otherwise it returns a pointer
+ * to the PPS source data struct (the refcounter is incremented by 1).
+ */
+
+struct pps_device *pps_get_source(int source)
+{
+	struct pps_device *pps;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pps_idr_lock, flags);
+
+	pps = idr_find(&pps_idr, source);
+	if (pps != NULL)
+		atomic_inc(&pps->usage);
+
+	spin_unlock_irqrestore(&pps_idr_lock, flags);
+
+	return pps;
+}
+
+/* pps_put_source - free the PPS source data
+ *
+ *	pps: a pointer to the PPS source.
+ *
+ * This function is used to free a PPS data struct if its refcount is 0.
+ */
+
+void pps_put_source(struct pps_device *pps)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&pps_idr_lock, flags);
+	BUG_ON(atomic_read(&pps->usage) == 0);
+
+	if (!atomic_dec_and_test(&pps->usage)) {
+		pps = NULL;
+		goto exit;
+	}
+
+	/* No more reference to the PPS source. We can safely remove the
+	 * PPS data struct.
+	 */
+	idr_remove(&pps_idr, pps->id);
+
+exit:
+	spin_unlock_irqrestore(&pps_idr_lock, flags);
+	kfree(pps);
+}
+
+/* pps_register_source - add a PPS source in the system
+ *
+ *	info: the PPS info struct
+ *	default_params: the default PPS parameters of the new source
+ *
+ * This function is used to add a new PPS source in the system. The new
+ * source is described by info's fields and it will have, as default PPS
+ * parameters, the ones specified into default_params.
+ *
+ * The function returns, in case of success, the PPS source ID.
+ */
+
+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(&pps_idr_lock);
+	err = idr_get_new(&pps_idr, pps, &id);
+	spin_unlock_irq(&pps_idr_lock);
+
+	if (err < 0)
+		goto kfree_pps;
+
+	id = id & MAX_ID_MASK;
+	if (id >= PPS_MAX_SOURCES) {
+		printk(KERN_ERR "pps: %s: too many 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, 1);
+
+	/* 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;
+	}
+
+	pr_info("new PPS source %s at ID %d\n", info->name, id);
+
+	return id;
+
+free_idr:
+	spin_lock_irq(&pps_idr_lock);
+	idr_remove(&pps_idr, id);
+	spin_unlock_irq(&pps_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);
+
+/* pps_unregister_source - remove a PPS source from the system
+ *
+ *	source: the PPS source ID
+ *
+ * This function is used to remove a previously registered PPS source from
+ * the system.
+ */
+
+void pps_unregister_source(int source)
+{
+	struct pps_device *pps;
+
+	spin_lock_irq(&pps_idr_lock);
+	pps = idr_find(&pps_idr, source);
+
+	if (!pps) {
+		BUG();
+		spin_unlock_irq(&pps_idr_lock);
+		return;
+	}
+	spin_unlock_irq(&pps_idr_lock);
+
+	pps_unregister_cdev(pps);
+	pps_put_source(pps);
+}
+EXPORT_SYMBOL(pps_unregister_source);
+
+/* pps_event - register a PPS event into the system
+ *
+ *	source: the PPS source ID
+ *	ts: the event timestamp
+ *	event: the event type
+ *	data: userdef pointer
+ *
+ * This function is used by each PPS client in order to register a new
+ * PPS event into the system (it's usually called inside an IRQ handler).
+ *
+ * If an echo function is associated with the PPS source it will be called
+ * as:
+ *	pps->info.echo(source, event, data);
+ */
+
+void pps_event(int source, struct pps_ktime *ts, int event, void *data)
+{
+	struct pps_device *pps;
+	unsigned long flags;
+
+	if ((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0) {
+		printk(KERN_ERR "pps: unknown event (%x) for source %d\n",
+			event, source);
+		return;
+	}
+
+	pps = pps_get_source(source);
+	if (!pps)
+		return;
+
+	pr_debug("PPS event on source %d at %llu.%06u\n",
+			pps->id, (unsigned long long) 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 */
+	pps_put_source(pps);
+}
+EXPORT_SYMBOL(pps_event);
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
new file mode 100644
index 0000000..ceff736
--- /dev/null
+++ b/drivers/pps/pps.c
@@ -0,0 +1,335 @@
+/*
+ * pps.c -- Main PPS support file
+ *
+ *
+ * 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.
+ */
+
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <linux/idr.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",
+					(long long) 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);
+	int found;
+
+	found = pps_get_source(pps->id) != 0;
+	if (!found)
+		return -ENODEV;
+
+	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 */
+	pps_put_source(pps);
+
+	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, NULL,
+							"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 stuff
+ */
+
+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: failed to allocate class\n");
+		return -ENOMEM;
+	}
+	pps_class->dev_attrs = pps_attrs;
+
+	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@linux.it>\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@linux.it>");
+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..99528a8
--- /dev/null
+++ b/drivers/pps/sysfs.c
@@ -0,0 +1,104 @@
+/*
+ * sysfs.c -- sysfs support
+ *
+ *
+ * Copyright (C) 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.
+ */
+
+
+#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);
+
+	if (!(pps->info.mode & PPS_CAPTUREASSERT))
+		return 0;
+
+	return sprintf(buf, "%lld.%09d#%d\n",
+			(long long) 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);
+
+	if (!(pps->info.mode & PPS_CAPTURECLEAR))
+		return 0;
+
+	return sprintf(buf, "%lld.%09d#%d\n",
+			(long long) 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);
+
+struct device_attribute pps_attrs[] = {
+	__ATTR(assert, S_IRUGO, pps_show_assert, NULL),
+	__ATTR(clear, S_IRUGO, pps_show_clear, NULL),
+	__ATTR(mode, S_IRUGO, pps_show_mode, NULL),
+	__ATTR(echo, S_IRUGO, pps_show_echo, NULL),
+	__ATTR(name, S_IRUGO, pps_show_name, NULL),
+	__ATTR(path, S_IRUGO, pps_show_path, NULL),
+	__ATTR_NULL,
+};
diff --git a/include/linux/Kbuild b/include/linux/Kbuild
index e531783..7f850e7 100644
--- a/include/linux/Kbuild
+++ b/include/linux/Kbuild
@@ -309,6 +309,7 @@ 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/pps.h b/include/linux/pps.h
new file mode 100644
index 0000000..b5c3cf9
--- /dev/null
+++ b/include/linux/pps.h
@@ -0,0 +1,202 @@
+/*
+ * pps.h -- PPS API kernel 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 _PPS_H_
+#define _PPS_H_
+
+#define PPS_VERSION		"5.3.3"
+#define PPS_MAX_SOURCES		16		/* should be enough... */
+
+/* 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		1
+#define PPS_API_VERS		PPS_API_VERS_1	/* we use API version 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', 0xa0)
+#define PPS_GETPARAMS		_IOR('p', 0xa1, struct pps_kparams *)
+#define PPS_SETPARAMS		_IOW('p', 0xa2, struct pps_kparams *)
+#define PPS_GETCAP		_IOR('p', 0xa3, int *)
+#define PPS_FETCH		_IOWR('p', 0xa4, struct pps_fdata *)
+
+#ifdef __KERNEL__
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+
+/*
+ * 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 */
+};
+
+/*
+ * Global variables
+ */
+
+extern spinlock_t pps_idr_lock;
+extern struct idr pps_idr;
+
+extern struct device_attribute pps_attrs[];
+
+/*
+ * Exported functions
+ */
+
+struct pps_device *pps_get_source(int source);
+extern void pps_put_source(struct pps_device *pps);
+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, struct pps_ktime *ts, int event, void *data);
+
+#endif /* __KERNEL__ */
+
+#endif /* _PPS_H_ */
-- 
1.5.4.3

[PATCH 2/9] PPS: userland header file for PPS API.

[Rodolfo Giometti]

This patch adds into the PPS's documentation directory a possible
implementation of the PPS API (RFC 2783) by using the LinuxPPS's char
devices.

This file is not just an example but it can be used into real
systems. :)

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
---
 Documentation/pps/timepps.h |  195 +++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 195 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/pps/timepps.h

diff --git a/Documentation/pps/timepps.h b/Documentation/pps/timepps.h
new file mode 100644
index 0000000..2372949
--- /dev/null
+++ b/Documentation/pps/timepps.h
@@ -0,0 +1,195 @@
+/*
+ * 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 <sys/syscall.h>
+#include <unistd.h>
+#include <errno.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;
+
+	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_ */
-- 
1.5.4.3

[PATCH 3/9] PPS: documentation programs and examples.

[Rodolfo Giometti]

Here some utilities and examples about the PPS API and the LinuxPPS
support.

* ppsldisc.c shows how to manage PPS line discipline;

* ppstest.c implements an useful testing program, while

* ppsfind tries to help the user into finding a specific PPS source by
  using its name or path.

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
---
 Documentation/pps/Makefile   |   28 ++++++++
 Documentation/pps/ppsfind    |   17 +++++
 Documentation/pps/ppsldisc.c |   46 +++++++++++++
 Documentation/pps/ppstest.c  |  151 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 242 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/pps/Makefile
 create mode 100644 Documentation/pps/ppsfind
 create mode 100644 Documentation/pps/ppsldisc.c
 create mode 100644 Documentation/pps/ppstest.c

diff --git a/Documentation/pps/Makefile b/Documentation/pps/Makefile
new file mode 100644
index 0000000..9841e6b
--- /dev/null
+++ b/Documentation/pps/Makefile
@@ -0,0 +1,28 @@
+TARGETS = ppstest ppsldisc
+
+CFLAGS += -Wall -O2 -D_GNU_SOURCE
+CFLAGS += -I .
+CFLAGS += -ggdb
+CFLAGS += -D__N_PPS=$(shell awk '/N_PPS/ {print $$3}' ../../include/linux/tty.h)
+
+# -- 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/ppsldisc.c b/Documentation/pps/ppsldisc.c
new file mode 100644
index 0000000..036e13b
--- /dev/null
+++ b/Documentation/pps/ppsldisc.c
@@ -0,0 +1,46 @@
+#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>
+
+#ifndef N_PPS
+#define N_PPS __N_PPS
+#endif
+
+void usage(char *name)
+{
+	fprintf(stderr, "usage: %s <ttyS>\n", name);
+
+	exit(EXIT_FAILURE);
+}
+
+int main(int argc, char *argv[])
+{
+	int fd;
+	int ldisc = N_PPS;
+	int ret;
+
+	if (argc < 2)
+		usage(argv[0]);
+
+	fd = open(argv[1], O_RDWR);
+	if (fd < 0) {
+		perror("open");
+		exit(EXIT_FAILURE);
+	}
+
+	ret = ioctl(fd, TIOCSETD, &ldisc);
+	if (ret < 0) {
+		perror("ioctl(TIOCSETD)");
+		exit(EXIT_FAILURE);
+	}
+
+	pause();
+
+	return 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;
+}
-- 
1.5.4.3

[PATCH 4/9] PPS: LinuxPPS clients support.

[Rodolfo Giometti]

Each PPS source can be registered/deregistered into the system by
using special modules called "clients". They simply define the PPS
sources' attributes and implement the time signal registartion
mechanism.

This patch adds a special directory for such clients and adds a dummy
client that can be useful to test system integrity on real systems.

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
---
 drivers/pps/Kconfig          |    2 +
 drivers/pps/Makefile         |    1 +
 drivers/pps/clients/Kconfig  |   18 ++++++
 drivers/pps/clients/Makefile |    9 +++
 drivers/pps/clients/ktimer.c |  124 ++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 154 insertions(+), 0 deletions(-)
 create mode 100644 drivers/pps/clients/Kconfig
 create mode 100644 drivers/pps/clients/Makefile
 create mode 100644 drivers/pps/clients/ktimer.c

diff --git a/drivers/pps/Kconfig b/drivers/pps/Kconfig
index cc2eb8e..1afe4e0 100644
--- a/drivers/pps/Kconfig
+++ b/drivers/pps/Kconfig
@@ -30,4 +30,6 @@ 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-$(CONFIG_PPS_DEBUG) := -DDEBUG
diff --git a/drivers/pps/clients/Kconfig b/drivers/pps/clients/Kconfig
new file mode 100644
index 0000000..60b83be
--- /dev/null
+++ b/drivers/pps/clients/Kconfig
@@ -0,0 +1,18 @@
+#
+# PPS clients configuration
+#
+
+if PPS
+
+comment "PPS clients support"
+
+config PPS_CLIENT_KTIMER
+	tristate "Kernel timer client (Testing client, use for debug)"
+	help
+	  If you say yes here you get support for a PPS debugging client
+	  which uses a kernel timer to generate the PPS signal.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called ktimer.ko.
+
+endif
diff --git a/drivers/pps/clients/Makefile b/drivers/pps/clients/Makefile
new file mode 100644
index 0000000..f3c1e39
--- /dev/null
+++ b/drivers/pps/clients/Makefile
@@ -0,0 +1,9 @@
+#
+# Makefile for PPS clients.
+#
+
+obj-$(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..259baa7
--- /dev/null
+++ b/drivers/pps/clients/ktimer.c
@@ -0,0 +1,124 @@
+/*
+ * 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.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");
-- 
1.5.4.3

[PATCH 5/9] ldisc: new dcd_change() method for line disciplines.

[Rodolfo Giometti]

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
---
 Documentation/serial/tty.txt |    4 ++++
 include/linux/tty_ldisc.h    |    8 ++++++++
 2 files changed, 12 insertions(+), 0 deletions(-)

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/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;
 	
-- 
1.5.4.3

[PATCH 6/9] ldisc n_tty: export all N_TTY ldisc methods.

[Rodolfo Giometti]

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
---
 drivers/char/n_tty.c |   32 +++++++++++++++++++++-----------
 include/linux/tty.h  |   16 ++++++++++++++++
 2 files changed, 37 insertions(+), 11 deletions(-)

diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
index efbfe96..9db2e35 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -43,10 +43,10 @@
 #include <linux/mm.h>
 #include <linux/string.h>
 #include <linux/slab.h>
-#include <linux/poll.h>
 #include <linux/bitops.h>
 #include <linux/audit.h>
 #include <linux/file.h>
+#include <linux/module.h>
 
 #include <asm/uaccess.h>
 #include <asm/system.h>
@@ -194,7 +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 */
@@ -210,6 +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
@@ -221,7 +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;
@@ -237,6 +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
@@ -921,13 +923,14 @@ 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)
 {
 	if (tty->fasync) {
 		set_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
@@ -942,7 +945,7 @@ 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;
@@ -1016,6 +1019,7 @@ 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)
 {
@@ -1037,7 +1041,7 @@ 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);
@@ -1116,6 +1120,7 @@ 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
@@ -1127,7 +1132,7 @@ 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) {
@@ -1135,6 +1140,7 @@ static void n_tty_close(struct tty_struct *tty)
 		tty->read_buf = NULL;
 	}
 }
+EXPORT_SYMBOL_GPL(n_tty_close);
 
 /**
  *	n_tty_open		-	open an ldisc
@@ -1146,7 +1152,7 @@ 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;
@@ -1165,6 +1171,7 @@ 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)
 {
@@ -1279,7 +1286,7 @@ 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;
@@ -1479,6 +1486,7 @@ do_it_again:
 	n_tty_set_room(tty);
 	return retval;
 }
+EXPORT_SYMBOL_GPL(n_tty_read);
 
 /**
  *	n_tty_write		-	write function for tty
@@ -1495,7 +1503,7 @@ do_it_again:
  *	This code must be sure never to sleep through a hangup.
  */
 
-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;
@@ -1567,6 +1575,7 @@ break_out:
 	remove_wait_queue(&tty->write_wait, &wait);
 	return (b - buf) ? b - buf : retval;
 }
+EXPORT_SYMBOL_GPL(n_tty_write);
 
 /**
  *	n_tty_poll		-	poll method for N_TTY
@@ -1582,7 +1591,7 @@ 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;
@@ -1609,6 +1618,7 @@ 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/include/linux/tty.h b/include/linux/tty.h
index 3b8121d..190ad4a 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>
 
@@ -432,6 +433,21 @@ 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;
-- 
1.5.4.3

[PATCH 7/9] PPS: serial clients support.

[Rodolfo Giometti]

Adds support, by using the PPS line discipline, for the PPS sources
connected with the CD (Carrier Detect) pin of a serial port.

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
---
 drivers/pps/clients/Kconfig     |    7 ++
 drivers/pps/clients/Makefile    |    1 +
 drivers/pps/clients/pps-ldisc.c |  155 +++++++++++++++++++++++++++++++++++++++
 drivers/serial/8250.c           |   13 +++
 include/linux/serial_core.h     |   11 +++-
 5 files changed, 186 insertions(+), 1 deletions(-)
 create mode 100644 drivers/pps/clients/pps-ldisc.c

diff --git a/drivers/pps/clients/Kconfig b/drivers/pps/clients/Kconfig
index 60b83be..487c1c8 100644
--- a/drivers/pps/clients/Kconfig
+++ b/drivers/pps/clients/Kconfig
@@ -15,4 +15,11 @@ config PPS_CLIENT_KTIMER
 	  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.
+
 endif
diff --git a/drivers/pps/clients/Makefile b/drivers/pps/clients/Makefile
index f3c1e39..9f5b988 100644
--- a/drivers/pps/clients/Makefile
+++ b/drivers/pps/clients/Makefile
@@ -3,6 +3,7 @@
 #
 
 obj-$(CONFIG_PPS_CLIENT_KTIMER)	+= ktimer.o
+obj-$(CONFIG_PPS_CLIENT_LDISC)	+= pps-ldisc.o
 
 ifeq ($(CONFIG_PPS_DEBUG),y)
 EXTRA_CFLAGS += -DDEBUG
diff --git a/drivers/pps/clients/pps-ldisc.c b/drivers/pps/clients/pps-ldisc.c
new file mode 100644
index 0000000..234867b
--- /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)
+{
+	int id = (int) 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, 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;
+	int 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((int) tty->disc_data);
+
+	pr_info("PPS source #%d \"%s\" added\n", ret, info.path);
+
+	return 0;
+}
+
+static void pps_tty_close(struct tty_struct *tty)
+{
+	int id = (int) tty->disc_data;
+
+	pps_unregister_source(id);
+	n_tty_close(tty);
+
+	pr_info("PPS source #%d removed\n", 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 303272a..b425116 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -2313,6 +2313,18 @@ 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)
 {
@@ -2523,6 +2535,7 @@ 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/serial_core.h b/include/linux/serial_core.h
index 4e4f127..cd6af20 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -491,9 +491,13 @@ 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;
 
-	port->icount.dcd++;
+	if (ld && ld->ops->dcd_change)
+		getnstimeofday(&ts);
 
+	port->icount.dcd++;
 #ifdef CONFIG_HARD_PPS
 	if ((port->flags & UPF_HARDPPS_CD) && status)
 		hardpps();
@@ -505,6 +509,11 @@ 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(port, status, &ts);
+	if (ld)
+		tty_ldisc_deref(ld);
 }
 
 /**
-- 
1.5.4.3

[PATCH 8/9] PPS: parallel port clients support.

[Rodolfo Giometti]

Adds support for the PPS sources connected with the interrupt pin of a
parallel port.

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
---
 drivers/char/lp.c           |   61 +++++++++++++++++++++++++++++++++++++++++++
 drivers/pps/clients/Kconfig |   10 +++++++
 include/linux/parport.h     |   22 +++++++++++++++
 3 files changed, 93 insertions(+), 0 deletions(-)

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/pps/clients/Kconfig b/drivers/pps/clients/Kconfig
index 487c1c8..b4054cd 100644
--- a/drivers/pps/clients/Kconfig
+++ b/drivers/pps/clients/Kconfig
@@ -22,4 +22,14 @@ config PPS_CLIENT_LDISC
 	  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/include/linux/parport.h b/include/linux/parport.h
index e1f83c5..4276941 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.h>
 #include <linux/irqreturn.h>
 #include <linux/semaphore.h>
 #include <asm/system.h>
@@ -326,6 +327,11 @@ 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 */
@@ -514,6 +520,22 @@ 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)
-- 
1.5.4.3

[PATCH 9/9] PPS: low level IRQ timestamps recording.

[Rodolfo Giometti]

Add low level IRQ timestamps recording for x86 (32 and 64 bits)
platforms and enable UART clients in order to use it.

This improves PPS precision. :)

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
---
 arch/x86/kernel/irq_32.c    |   16 ++++++++++++++++
 arch/x86/kernel/irq_64.c    |   21 +++++++++++++++++++--
 drivers/pps/Kconfig         |   12 ++++++++++++
 include/linux/pps.h         |    1 +
 include/linux/serial_core.h |    7 ++++++-
 5 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index a513826..7fce1e2 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -15,6 +15,7 @@
 #include <linux/notifier.h>
 #include <linux/cpu.h>
 #include <linux/delay.h>
+#include <linux/pps.h>
 
 #include <asm/apic.h>
 #include <asm/uaccess.h>
@@ -25,6 +26,11 @@ 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)
@@ -204,7 +210,12 @@ unsigned int do_IRQ(struct pt_regs *regs)
 	unsigned vector = ~regs->orig_ax;
 	struct irq_desc *desc;
 	unsigned irq;
+#ifdef CONFIG_PPS_IRQ_EVENTS
+	struct timespec ts;
 
+	/* Get IRQ timestamps as soon as possible for the PPS layer */
+	getnstimeofday(&ts);
+#endif
 
 	old_regs = set_irq_regs(regs);
 	irq_enter();
@@ -219,6 +230,11 @@ unsigned int do_IRQ(struct pt_regs *regs)
 		BUG();
 	}
 
+#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 60eb84e..a1457a0 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -17,6 +17,12 @@
 #include <asm/io_apic.h>
 #include <asm/idle.h>
 #include <asm/smp.h>
+#include <linux/pps.h>
+
+#ifdef CONFIG_PPS_IRQ_EVENTS
+struct timespec pps_irq_ts[NR_IRQS];
+EXPORT_SYMBOL(pps_irq_ts);
+#endif
 
 #ifdef CONFIG_DEBUG_STACKOVERFLOW
 /*
@@ -51,6 +57,12 @@ asmlinkage unsigned int do_IRQ(struct pt_regs *regs)
 {
 	struct pt_regs *old_regs = set_irq_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
 
 	/* high bit used in ret_from_ code  */
 	unsigned vector = ~regs->orig_ax;
@@ -65,9 +77,14 @@ asmlinkage unsigned int do_IRQ(struct pt_regs *regs)
 #endif
 
 	desc = irq_to_desc(irq);
-	if (likely(desc))
+	if (likely(desc)) {
+#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);
-	else {
+	} else {
 		if (!disable_apic)
 			ack_APIC_irq();
 
diff --git a/drivers/pps/Kconfig b/drivers/pps/Kconfig
index 1afe4e0..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
diff --git a/include/linux/pps.h b/include/linux/pps.h
index b5c3cf9..191190e 100644
--- a/include/linux/pps.h
+++ b/include/linux/pps.h
@@ -181,6 +181,7 @@ struct pps_device {
 
 extern spinlock_t pps_idr_lock;
 extern struct idr pps_idr;
+extern struct timespec pps_irq_ts[];
 
 extern struct device_attribute pps_attrs[];
 
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index cd6af20..eac89e6 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -168,6 +168,7 @@
 #include <linux/tty.h>
 #include <linux/mutex.h>
 #include <linux/sysrq.h>
+#include <linux/pps.h>
 
 struct uart_port;
 struct uart_info;
@@ -495,7 +496,11 @@ uart_handle_dcd_change(struct uart_port *port, unsigned int status)
 	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
@@ -511,7 +516,7 @@ uart_handle_dcd_change(struct uart_port *port, unsigned int status)
 	}
 
 	if (ld && ld->ops->dcd_change)
-		ld->ops->dcd_change(port, status, &ts);
+		ld->ops->dcd_change(info->port.tty, status, &ts);
 	if (ld)
 		tty_ldisc_deref(ld);
 }
-- 
1.5.4.3

Re: LinuxPPS (Version 10): the PPS Linux implementation.

[Lennart Sorensen]

On Wed, Nov 26, 2008 at 02:42:40PM +0100, Rodolfo Giometti wrote:
> Note: Very few changes since last post! Please, add this patch set
>       into next available merge window.
> 
> This patch set adds the PPS support into Linux.
> 
> PPS means "pulse per second" and its API is specified by RFC 2783
> (Pulse-Per-Second API for UNIX-like Operating Systems, Version 1.0).
> 
> The code has been tested with the NTPD program
> (http://www.eecis.udel.edu/~mills/ntp/html/index.html) and several GPS
> antennae.

Yay!  Thank you for still working on this.  I am using 5.3.1 at the
moment on 2.6.26 (was using 3.0.0 for a long time on 2.6.18) and so far
things are great.

-- 
Len Sorensen

Re: [PATCH 1/9] LinuxPPS core support.

[Lennart Sorensen]

On Tue, Nov 25, 2008 at 05:20:19PM +0000, David Woodhouse wrote:
> On Tue, 2008-11-25 at 17:45 +0100, Rodolfo Giometti wrote:
> > In the past I got a suggestion in using ??antennae?? instead of
> > ??antennas??... do you think I can leave it anyway? :)
> 
> Antennae is correct.

wikipedia (not that that really means much) claims antennae is correct
for biology and antennas is correct for electronics.

That seems to match what I do, not that I really ever talk about biology
myself. :)

Of course I am one of those people that thing disc means optical and
disk means magnetic.  Or disc for spiral track and disk for circular
tracks.  Both seem to work consistently, although I might be wrong and
some optical media may in fact use circular tracks.

-- 
Len Sorensen