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LinuxPPS: core support

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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>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rodolfo Giometti 2009-06-17 16:28:37 -07:00 committed by Linus Torvalds
parent 8820f27ad9
commit eae9d2ba0c
14 changed files with 1249 additions and 0 deletions
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73
Documentation/ABI/testing/sysfs-pps Normal file
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@ -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.

2
Documentation/ioctl/ioctl-number.txt
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@ -149,6 +149,8 @@ Code Seq# Include File Comments
'p' 40-7F linux/nvram.h
'p' 80-9F user-space parport
<mailto:tim@cyberelk.net>
'p' a1-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>

172
Documentation/pps/pps.txt Normal file
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@ -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/).

7
MAINTAINERS
View file

@ -4577,6 +4577,13 @@ S: Maintained
F: drivers/net/pppol2tp.c
F: include/linux/if_pppol2tp.h
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

2
drivers/Kconfig
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@ -52,6 +52,8 @@ source "drivers/i2c/Kconfig"
source "drivers/spi/Kconfig"
source "drivers/pps/Kconfig"
source "drivers/gpio/Kconfig"
source "drivers/w1/Kconfig"

1
drivers/Makefile
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@ -72,6 +72,7 @@ obj-$(CONFIG_INPUT) += input/
obj-$(CONFIG_I2O) += message/
obj-$(CONFIG_RTC_LIB) += rtc/
obj-y += i2c/ media/
obj-$(CONFIG_PPS) += pps/
obj-$(CONFIG_W1) += w1/
obj-$(CONFIG_POWER_SUPPLY) += power/
obj-$(CONFIG_HWMON) += hwmon/

33
drivers/pps/Kconfig Normal file
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@ -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

8
drivers/pps/Makefile Normal file
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@ -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

329
drivers/pps/kapi.c Normal file
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@ -0,0 +1,329 @@
/*
* kernel API
*
*
* Copyright (C) 2005-2009 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_kernel.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;
}
/* These initializations must be done before calling idr_get_new()
* in order to avoid reces into pps_event().
*/
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);
/* 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);
/* Now really allocate the PPS source.
* After idr_get_new() calling the new source will be freely available
* into the kernel.
*/
err = idr_get_new(&pps_idr, pps, &id);
if (err < 0) {
spin_unlock_irq(&pps_idr_lock);
goto kfree_pps;
}
id = id & MAX_ID_MASK;
if (id >= PPS_MAX_SOURCES) {
spin_unlock_irq(&pps_idr_lock);
printk(KERN_ERR "pps: %s: too many PPS sources in the system\n",
info->name);
err = -EBUSY;
goto free_idr;
}
pps->id = id;
spin_unlock_irq(&pps_idr_lock);
/* 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);

312
drivers/pps/pps.c Normal file
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@ -0,0 +1,312 @@
/*
* PPS core file
*
*
* Copyright (C) 2005-2009 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_kernel.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 long pps_cdev_ioctl(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_GETPARAMS:
pr_debug("PPS_GETPARAMS: source %d\n", pps->id);
/* 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;
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);
err = put_user(pps->info.mode, iuarg);
if (err)
return -EFAULT;
break;
case PPS_FETCH:
pr_debug("PPS_FETCH: source %d\n", pps->id);
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,
.unlocked_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);
unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
}
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");

98
drivers/pps/sysfs.c Normal file
View file

@ -0,0 +1,98 @@
/*
* PPS sysfs support
*
*
* Copyright (C) 2007-2009 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_kernel.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);
}
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);
}
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);
}
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);
}
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);
}
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);
}
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,
};

1
include/linux/Kbuild
View file

@ -308,6 +308,7 @@ 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 += quota.h
unifdef-y += random.h

122
include/linux/pps.h Normal file
View file

@ -0,0 +1,122 @@
/*
* PPS API header
*
* Copyright (C) 2005-2009 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 "5.3.6"
#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
*/
#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_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 *)
#endif /* _PPS_H_ */

89
include/linux/pps_kernel.h Normal file
View file

@ -0,0 +1,89 @@
/*
* PPS API kernel header
*
* Copyright (C) 2009 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/pps.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/time.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 timespec pps_irq_ts[];
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);