docs: ABI: Add sysfs documentation for timecard (d7050a2b) · Commits · EulixOS / Software / Kernel

Documentation/ABI/testing/sysfs-timecard

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		What: /sys/class/timecard/
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: This directory contains files and directories
		providing a standardized interface to the ancillary
		features of the OpenCompute timecard.

		What: /sys/class/timecard/ocpN/
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: This directory contains the attributes of the Nth timecard
		registered.

		What: /sys/class/timecard/ocpN/available_clock_sources
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: (RO) The list of available time sources that the PHC
		uses for clock adjustments.

		==== =================================================
		NONE no adjustments
		PPS adjustments come from the PPS1 selector (default)
		TOD adjustments from the GNSS/TOD module
		IRIG adjustments from external IRIG-B signal
		DCF adjustments from external DCF signal
		==== =================================================

		What: /sys/class/timecard/ocpN/available_sma_inputs
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: (RO) Set of available destinations (sinks) for a SMA
		input signal.

		===== ================================================
		10Mhz signal is used as the 10Mhz reference clock
		PPS1 signal is sent to the PPS1 selector
		PPS2 signal is sent to the PPS2 selector
		TS1 signal is sent to timestamper 1
		TS2 signal is sent to timestamper 2
		IRIG signal is sent to the IRIG-B module
		DCF signal is sent to the DCF module
		===== ================================================

		What: /sys/class/timecard/ocpN/available_sma_outputs
		Date: May 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: (RO) Set of available sources for a SMA output signal.

		===== ================================================
		10Mhz output is from the 10Mhz reference clock
		PHC output PPS is from the PHC clock
		MAC output PPS is from the Miniature Atomic Clock
		GNSS output PPS is from the GNSS module
		GNSS2 output PPS is from the second GNSS module
		IRIG output is from the PHC, in IRIG-B format
		DCF output is from the PHC, in DCF format
		===== ================================================

		What: /sys/class/timecard/ocpN/clock_source
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: (RW) Contains the current synchronization source used by
		the PHC. May be changed by writing one of the listed
		values from the available_clock_sources attribute set.

		What: /sys/class/timecard/ocpN/gnss_sync
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: (RO) Indicates whether a valid GNSS signal is received,
		or when the signal was lost.

		What: /sys/class/timecard/ocpN/i2c
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: This optional attribute links to the associated i2c device.

		What: /sys/class/timecard/ocpN/irig_b_mode
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: (RW) An integer from 0-7 indicating the timecode format
		of the IRIG-B output signal: B00<n>

		What: /sys/class/timecard/ocpN/pps
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: This optional attribute links to the associated PPS device.

		What: /sys/class/timecard/ocpN/ptp
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: This attribute links to the associated PTP device.

		What: /sys/class/timecard/ocpN/serialnum
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: (RO) Provides the serial number of the timecard.

		What: /sys/class/timecard/ocpN/sma1
		What: /sys/class/timecard/ocpN/sma2
		What: /sys/class/timecard/ocpN/sma3
		What: /sys/class/timecard/ocpN/sma4
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: (RW) These attributes specify the direction of the signal
		on the associated SMA connectors, and also the signal sink
		or source.

		The display format of the attribute is a space separated
		list of signals, prefixed by the input/output direction.

		The signal direction may be changed (if supported) by
		prefixing the signal list with either "in:" or "out:".
		If neither prefix is present, then the direction is unchanged.

		The output signal may be changed by writing one of the listed
		values from the available_sma_outputs attribute set.

		The input destinations may be changed by writing multiple
		values from the available_sma_inputs attribute set,
		separated by spaces. If there are duplicated input
		destinations between connectors, the lowest numbered SMA
		connector is given priority.

		Note that not all input combinations may make sense.

		The 10Mhz reference clock input is currently only valid
		on SMA1 and may not be combined with other destination sinks.

		What: /sys/class/timecard/ocpN/ts_window_adjust
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: (RW) When retrieving the PHC with the PTP SYS_OFFSET_EXTENDED
		ioctl, a system timestamp is made before and after the PHC
		time is retrieved. The midpoint between the two system
		timestamps is usually taken to be the SYS time associated
		with the PHC time. This estimate may be wrong, as it depends
		on PCI latencies, and when the PHC time was latched

		The attribute value reduces the end timestamp by the given
		number of nanoseconds, so the computed midpoint matches the
		retrieved PHC time.

		The initial value is set based on measured PCI latency and
		the estimated point where the FPGA latches the PHC time. This
		value may be changed by writing an unsigned integer.

		What: /sys/class/timecard/ocpN/ttyGNSS
		What: /sys/class/timecard/ocpN/ttyGNSS2
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: These optional attributes link to the TTY serial ports
		associated with the GNSS devices.

		What: /sys/class/timecard/ocpN/ttyMAC
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: This optional attribute links to the TTY serial port
		associated with the Miniature Atomic Clock.

		What: /sys/class/timecard/ocpN/ttyNMEA
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: This optional attribute links to the TTY serial port
		which outputs the PHC time in NMEA ZDA format.

		What: /sys/class/timecard/ocpN/utc_tai_offset
		Date: September 2021
		Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
		Description: (RW) The DCF and IRIG output signals are in UTC, while the
		TimeCard operates on TAI. This attribute allows setting the
		offset in seconds, which is added to the TAI timebase for
		these formats.

		The offset may be changed by writing an unsigned integer.