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 --- Documentation/ABI/testing/sysfs-pps | 73 +++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-pps (limited to 'Documentation/ABI') diff --git a/Documentation/ABI/testing/sysfs-pps b/Documentation/ABI/testing/sysfs-pps new file mode 100644 index 000000000000..25028c7bc37d --- /dev/null +++ b/Documentation/ABI/testing/sysfs-pps @@ -0,0 +1,73 @@ +What: /sys/class/pps/ +Date: February 2008 +Contact: Rodolfo Giometti +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 +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 +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: + + .# + + 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 +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: + + .# + + 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 +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 +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 +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 +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. -- cgit v1.2.2