1What:		/sys/class/ptp/
2Date:		September 2010
3Contact:	Richard Cochran <richardcochran@gmail.com>
4Description:
5		This directory contains files and directories
6		providing a standardized interface to the ancillary
7		features of PTP hardware clocks.
8
9What:		/sys/class/ptp/ptpN/
10Date:		September 2010
11Contact:	Richard Cochran <richardcochran@gmail.com>
12Description:
13		This directory contains the attributes of the Nth PTP
14		hardware clock registered into the PTP class driver
15		subsystem.
16
17What:		/sys/class/ptp/ptpN/clock_name
18Date:		September 2010
19Contact:	Richard Cochran <richardcochran@gmail.com>
20Description:
21		This file contains the name of the PTP hardware clock
22		as a human readable string. The purpose of this
23		attribute is to provide the user with a "friendly
24		name" and to help distinguish PHY based devices from
25		MAC based ones. The string does not necessarily have
26		to be any kind of unique id.
27
28What:		/sys/class/ptp/ptpN/max_adjustment
29Date:		September 2010
30Contact:	Richard Cochran <richardcochran@gmail.com>
31Description:
32		This file contains the PTP hardware clock's maximum
33		frequency adjustment value (a positive integer) in
34		parts per billion.
35
36What:		/sys/class/ptp/ptpN/n_alarms
37Date:		September 2010
38Contact:	Richard Cochran <richardcochran@gmail.com>
39Description:
40		This file contains the number of periodic or one shot
41		alarms offer by the PTP hardware clock.
42
43What:		/sys/class/ptp/ptpN/n_external_timestamps
44Date:		September 2010
45Contact:	Richard Cochran <richardcochran@gmail.com>
46Description:
47		This file contains the number of external timestamp
48		channels offered by the PTP hardware clock.
49
50What:		/sys/class/ptp/ptpN/n_periodic_outputs
51Date:		September 2010
52Contact:	Richard Cochran <richardcochran@gmail.com>
53Description:
54		This file contains the number of programmable periodic
55		output channels offered by the PTP hardware clock.
56
57What:		/sys/class/ptp/ptpN/pps_avaiable
58Date:		September 2010
59Contact:	Richard Cochran <richardcochran@gmail.com>
60Description:
61		This file indicates whether the PTP hardware clock
62		supports a Pulse Per Second to the host CPU. Reading
63		"1" means that the PPS is supported, while "0" means
64		not supported.
65
66What:		/sys/class/ptp/ptpN/extts_enable
67Date:		September 2010
68Contact:	Richard Cochran <richardcochran@gmail.com>
69Description:
70		This write-only file enables or disables external
71		timestamps. To enable external timestamps, write the
72		channel index followed by a "1" into the file.
73		To disable external timestamps, write the channel
74		index followed by a "0" into the file.
75
76What:		/sys/class/ptp/ptpN/fifo
77Date:		September 2010
78Contact:	Richard Cochran <richardcochran@gmail.com>
79Description:
80		This file provides timestamps on external events, in
81		the form of three integers: channel index, seconds,
82		and nanoseconds.
83
84What:		/sys/class/ptp/ptpN/period
85Date:		September 2010
86Contact:	Richard Cochran <richardcochran@gmail.com>
87Description:
88		This write-only file enables or disables periodic
89		outputs. To enable a periodic output, write five
90		integers into the file: channel index, start time
91		seconds, start time nanoseconds, period seconds, and
92		period nanoseconds. To disable a periodic output, set
93		all the seconds and nanoseconds values to zero.
94
95What:		/sys/class/ptp/ptpN/pps_enable
96Date:		September 2010
97Contact:	Richard Cochran <richardcochran@gmail.com>
98Description:
99		This write-only file enables or disables delivery of
100		PPS events to the Linux PPS subsystem. To enable PPS
101		events, write a "1" into the file. To disable events,
102		write a "0" into the file.
103