LinuxPPS: core support
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>
diff --git a/include/linux/pps_kernel.h b/include/linux/pps_kernel.h
new file mode 100644
index 0000000..e0a193f
--- /dev/null
+++ b/include/linux/pps_kernel.h
@@ -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);