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/n_pins
58Date:		March 2014
59Contact:	Richard Cochran <richardcochran@gmail.com>
60Description:
61		This file contains the number of programmable pins
62		offered by the PTP hardware clock.
63
64What:		/sys/class/ptp/ptpN/pins
65Date:		March 2014
66Contact:	Richard Cochran <richardcochran@gmail.com>
67Description:
68		This directory contains one file for each programmable
69		pin offered by the PTP hardware clock. The file name
70		is the hardware dependent pin name. Reading from this
71		file produces two numbers, the assigned function (see
72		the `PTP_PF_` enumeration values in linux/ptp_clock.h)
73		and the channel number. The function and channel
74		assignment may be changed by two writing numbers into
75		the file.
76
77What:		/sys/class/ptp/ptpN/pps_available
78Date:		September 2010
79Contact:	Richard Cochran <richardcochran@gmail.com>
80Description:
81		This file indicates whether the PTP hardware clock
82		supports a Pulse Per Second to the host CPU. Reading
83		"1" means that the PPS is supported, while "0" means
84		not supported.
85
86What:		/sys/class/ptp/ptpN/extts_enable
87Date:		September 2010
88Contact:	Richard Cochran <richardcochran@gmail.com>
89Description:
90		This write-only file enables or disables external
91		timestamps. To enable external timestamps, write the
92		channel index followed by a "1" into the file.
93		To disable external timestamps, write the channel
94		index followed by a "0" into the file.
95
96What:		/sys/class/ptp/ptpN/fifo
97Date:		September 2010
98Contact:	Richard Cochran <richardcochran@gmail.com>
99Description:
100		This file provides timestamps on external events, in
101		the form of three integers: channel index, seconds,
102		and nanoseconds.
103
104What:		/sys/class/ptp/ptpN/period
105Date:		September 2010
106Contact:	Richard Cochran <richardcochran@gmail.com>
107Description:
108		This write-only file enables or disables periodic
109		outputs. To enable a periodic output, write five
110		integers into the file: channel index, start time
111		seconds, start time nanoseconds, period seconds, and
112		period nanoseconds. To disable a periodic output, set
113		all the seconds and nanoseconds values to zero.
114
115What:		/sys/class/ptp/ptpN/pps_enable
116Date:		September 2010
117Contact:	Richard Cochran <richardcochran@gmail.com>
118Description:
119		This write-only file enables or disables delivery of
120		PPS events to the Linux PPS subsystem. To enable PPS
121		events, write a "1" into the file. To disable events,
122		write a "0" into the file.
123