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