From eae9d2ba0cfc27a2ad9765f23efb98fb80d80234 Mon Sep 17 00:00:00 2001 From: Rodolfo Giometti Date: Wed, 17 Jun 2009 16:28:37 -0700 Subject: 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 Cc: David Woodhouse Cc: Greg KH Cc: Randy Dunlap Cc: Kay Sievers Acked-by: Alan Cox Cc: Michael Kerrisk Cc: Christoph Hellwig Cc: Roman Zippel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/pps/sysfs.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) create mode 100644 drivers/pps/sysfs.c (limited to 'drivers/pps/sysfs.c') diff --git a/drivers/pps/sysfs.c b/drivers/pps/sysfs.c new file mode 100644 index 000000000000..ef0978c71eee --- /dev/null +++ b/drivers/pps/sysfs.c @@ -0,0 +1,98 @@ +/* + * PPS sysfs support + * + * + * Copyright (C) 2007-2009 Rodolfo Giometti + * + * 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 +#include +#include +#include + +/* + * 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, +}; -- cgit v1.2.3