There has been some confusion among PHC driver authors about the intended purpose of the clock_name attribute. This patch expands the documation in order to clarify how the clock_name field should be understood. Signed-off-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
		
			
				
	
	
		
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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. The purpose of this
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		attribute is to provide the user with a "friendly
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		name" and to help distinguish PHY based devices from
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		MAC based ones. The string does not necessarily have
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		to be any kind of unique id.
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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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