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.
23
24What:		/sys/class/ptp/ptpN/max_adjustment
25Date:		September 2010
26Contact:	Richard Cochran <richardcochran@gmail.com>
27Description:
28		This file contains the PTP hardware clock's maximum
29		frequency adjustment value (a positive integer) in
30		parts per billion.
31
32What:		/sys/class/ptp/ptpN/n_alarms
33Date:		September 2010
34Contact:	Richard Cochran <richardcochran@gmail.com>
35Description:
36		This file contains the number of periodic or one shot
37		alarms offer by the PTP hardware clock.
38
39What:		/sys/class/ptp/ptpN/n_external_timestamps
40Date:		September 2010
41Contact:	Richard Cochran <richardcochran@gmail.com>
42Description:
43		This file contains the number of external timestamp
44		channels offered by the PTP hardware clock.
45
46What:		/sys/class/ptp/ptpN/n_periodic_outputs
47Date:		September 2010
48Contact:	Richard Cochran <richardcochran@gmail.com>
49Description:
50		This file contains the number of programmable periodic
51		output channels offered by the PTP hardware clock.
52
53What:		/sys/class/ptp/ptpN/pps_avaiable
54Date:		September 2010
55Contact:	Richard Cochran <richardcochran@gmail.com>
56Description:
57		This file indicates whether the PTP hardware clock
58		supports a Pulse Per Second to the host CPU. Reading
59		"1" means that the PPS is supported, while "0" means
60		not supported.
61
62What:		/sys/class/ptp/ptpN/extts_enable
63Date:		September 2010
64Contact:	Richard Cochran <richardcochran@gmail.com>
65Description:
66		This write-only file enables or disables external
67		timestamps. To enable external timestamps, write the
68		channel index followed by a "1" into the file.
69		To disable external timestamps, write the channel
70		index followed by a "0" into the file.
71
72What:		/sys/class/ptp/ptpN/fifo
73Date:		September 2010
74Contact:	Richard Cochran <richardcochran@gmail.com>
75Description:
76		This file provides timestamps on external events, in
77		the form of three integers: channel index, seconds,
78		and nanoseconds.
79
80What:		/sys/class/ptp/ptpN/period
81Date:		September 2010
82Contact:	Richard Cochran <richardcochran@gmail.com>
83Description:
84		This write-only file enables or disables periodic
85		outputs. To enable a periodic output, write five
86		integers into the file: channel index, start time
87		seconds, start time nanoseconds, period seconds, and
88		period nanoseconds. To disable a periodic output, set
89		all the seconds and nanoseconds values to zero.
90
91What:		/sys/class/ptp/ptpN/pps_enable
92Date:		September 2010
93Contact:	Richard Cochran <richardcochran@gmail.com>
94Description:
95		This write-only file enables or disables delivery of
96		PPS events to the Linux PPS subsystem. To enable PPS
97		events, write a "1" into the file. To disable events,
98		write a "0" into the file.
99