mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-25 03:30:53 +07:00
eae9d2ba0c
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>
99 lines
2.7 KiB
C
99 lines
2.7 KiB
C
/*
|
|
* 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,
|
|
};
|