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ptp: Added a brand new class driver for ptp clocks.

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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>
This commit is contained in:
Richard Cochran
2011-04-22 12:03:08 +02:00
committed by John Stultz
parent caebc160ce
commit d94ba80ebb
16 changed files with 1695 additions and 0 deletions
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What: /sys/class/ptp/
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
This directory contains files and directories
providing a standardized interface to the ancillary
features of PTP hardware clocks.
What: /sys/class/ptp/ptpN/
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
This directory contains the attributes of the Nth PTP
hardware clock registered into the PTP class driver
subsystem.
What: /sys/class/ptp/ptpN/clock_name
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
This file contains the name of the PTP hardware clock
as a human readable string.
What: /sys/class/ptp/ptpN/max_adjustment
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
This file contains the PTP hardware clock's maximum
frequency adjustment value (a positive integer) in
parts per billion.
What: /sys/class/ptp/ptpN/n_alarms
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
This file contains the number of periodic or one shot
alarms offer by the PTP hardware clock.
What: /sys/class/ptp/ptpN/n_external_timestamps
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
This file contains the number of external timestamp
channels offered by the PTP hardware clock.
What: /sys/class/ptp/ptpN/n_periodic_outputs
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
This file contains the number of programmable periodic
output channels offered by the PTP hardware clock.
What: /sys/class/ptp/ptpN/pps_avaiable
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
This file indicates whether the PTP hardware clock
supports a Pulse Per Second to the host CPU. Reading
"1" means that the PPS is supported, while "0" means
not supported.
What: /sys/class/ptp/ptpN/extts_enable
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
This write-only file enables or disables external
timestamps. To enable external timestamps, write the
channel index followed by a "1" into the file.
To disable external timestamps, write the channel
index followed by a "0" into the file.
What: /sys/class/ptp/ptpN/fifo
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
This file provides timestamps on external events, in
the form of three integers: channel index, seconds,
and nanoseconds.
What: /sys/class/ptp/ptpN/period
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
This write-only file enables or disables periodic
outputs. To enable a periodic output, write five
integers into the file: channel index, start time
seconds, start time nanoseconds, period seconds, and
period nanoseconds. To disable a periodic output, set
all the seconds and nanoseconds values to zero.
What: /sys/class/ptp/ptpN/pps_enable
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
Description:
This write-only file enables or disables delivery of
PPS events to the Linux PPS subsystem. To enable PPS
events, write a "1" into the file. To disable events,
write a "0" into the file.