mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
synced 2025-10-31 03:13:59 +00:00
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>
90 lines
2.5 KiB
C
90 lines
2.5 KiB
C
/*
|
|
* 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);
|