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authorRichard Cochran <richardcochran@gmail.com>2011-04-22 06:03:08 -0400
committerJohn Stultz <john.stultz@linaro.org>2011-05-23 16:01:00 -0400
commitd94ba80ebbea17f036cecb104398fbcd788aa742 (patch)
tree7fe40228c5ea2bb77f2892b722d27155df8c1157 /Documentation/ABI
parentcaebc160ce3f76761cc62ad96ef6d6f30f54e3dd (diff)
ptp: Added a brand new class driver for ptp clocks.
This patch adds an infrastructure for hardware clocks that implement IEEE 1588, the Precision Time Protocol (PTP). A class driver offers a registration method to particular hardware clock drivers. Each clock is presented as a standard POSIX clock. The ancillary clock features are exposed in two different ways, via the sysfs and by a character device. Signed-off-by: Richard Cochran <richard.cochran@omicron.at> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'Documentation/ABI')
-rw-r--r--Documentation/ABI/testing/sysfs-ptp98
1 files changed, 98 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-ptp b/Documentation/ABI/testing/sysfs-ptp
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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.