forked from Minki/linux
docs: ABI: Add sysfs documentation for timecard
This patch describes the sysfs interface implemented by the ptp_ocp driver, under /sys/class/timecard. Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Jonathan Lemon
David S. Miller
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Documentation/ABI/testing/sysfs-timecard
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Documentation/ABI/testing/sysfs-timecard
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What: /sys/class/timecard/
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: This directory contains files and directories
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providing a standardized interface to the ancillary
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features of the OpenCompute timecard.
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What: /sys/class/timecard/ocpN/
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: This directory contains the attributes of the Nth timecard
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registered.
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What: /sys/class/timecard/ocpN/available_clock_sources
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: (RO) The list of available time sources that the PHC
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uses for clock adjustments.
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==== =================================================
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NONE no adjustments
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PPS adjustments come from the PPS1 selector (default)
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TOD adjustments from the GNSS/TOD module
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IRIG adjustments from external IRIG-B signal
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DCF adjustments from external DCF signal
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==== =================================================
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What: /sys/class/timecard/ocpN/available_sma_inputs
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: (RO) Set of available destinations (sinks) for a SMA
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input signal.
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===== ================================================
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10Mhz signal is used as the 10Mhz reference clock
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PPS1 signal is sent to the PPS1 selector
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PPS2 signal is sent to the PPS2 selector
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TS1 signal is sent to timestamper 1
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TS2 signal is sent to timestamper 2
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IRIG signal is sent to the IRIG-B module
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DCF signal is sent to the DCF module
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===== ================================================
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What: /sys/class/timecard/ocpN/available_sma_outputs
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Date: May 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: (RO) Set of available sources for a SMA output signal.
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===== ================================================
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10Mhz output is from the 10Mhz reference clock
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PHC output PPS is from the PHC clock
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MAC output PPS is from the Miniature Atomic Clock
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GNSS output PPS is from the GNSS module
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GNSS2 output PPS is from the second GNSS module
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IRIG output is from the PHC, in IRIG-B format
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DCF output is from the PHC, in DCF format
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===== ================================================
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What: /sys/class/timecard/ocpN/clock_source
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: (RW) Contains the current synchronization source used by
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the PHC. May be changed by writing one of the listed
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values from the available_clock_sources attribute set.
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What: /sys/class/timecard/ocpN/gnss_sync
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: (RO) Indicates whether a valid GNSS signal is received,
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or when the signal was lost.
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What: /sys/class/timecard/ocpN/i2c
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: This optional attribute links to the associated i2c device.
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What: /sys/class/timecard/ocpN/irig_b_mode
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: (RW) An integer from 0-7 indicating the timecode format
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of the IRIG-B output signal: B00<n>
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What: /sys/class/timecard/ocpN/pps
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: This optional attribute links to the associated PPS device.
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What: /sys/class/timecard/ocpN/ptp
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: This attribute links to the associated PTP device.
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What: /sys/class/timecard/ocpN/serialnum
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: (RO) Provides the serial number of the timecard.
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What: /sys/class/timecard/ocpN/sma1
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What: /sys/class/timecard/ocpN/sma2
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What: /sys/class/timecard/ocpN/sma3
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What: /sys/class/timecard/ocpN/sma4
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: (RW) These attributes specify the direction of the signal
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on the associated SMA connectors, and also the signal sink
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or source.
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The display format of the attribute is a space separated
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list of signals, prefixed by the input/output direction.
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The signal direction may be changed (if supported) by
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prefixing the signal list with either "in:" or "out:".
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If neither prefix is present, then the direction is unchanged.
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The output signal may be changed by writing one of the listed
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values from the available_sma_outputs attribute set.
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The input destinations may be changed by writing multiple
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values from the available_sma_inputs attribute set,
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separated by spaces. If there are duplicated input
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destinations between connectors, the lowest numbered SMA
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connector is given priority.
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Note that not all input combinations may make sense.
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The 10Mhz reference clock input is currently only valid
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on SMA1 and may not be combined with other destination sinks.
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What: /sys/class/timecard/ocpN/ts_window_adjust
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: (RW) When retrieving the PHC with the PTP SYS_OFFSET_EXTENDED
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ioctl, a system timestamp is made before and after the PHC
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time is retrieved. The midpoint between the two system
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timestamps is usually taken to be the SYS time associated
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with the PHC time. This estimate may be wrong, as it depends
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on PCI latencies, and when the PHC time was latched
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The attribute value reduces the end timestamp by the given
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number of nanoseconds, so the computed midpoint matches the
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retrieved PHC time.
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The initial value is set based on measured PCI latency and
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the estimated point where the FPGA latches the PHC time. This
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value may be changed by writing an unsigned integer.
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What: /sys/class/timecard/ocpN/ttyGNSS
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What: /sys/class/timecard/ocpN/ttyGNSS2
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: These optional attributes link to the TTY serial ports
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associated with the GNSS devices.
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What: /sys/class/timecard/ocpN/ttyMAC
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: This optional attribute links to the TTY serial port
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associated with the Miniature Atomic Clock.
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What: /sys/class/timecard/ocpN/ttyNMEA
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: This optional attribute links to the TTY serial port
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which outputs the PHC time in NMEA ZDA format.
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What: /sys/class/timecard/ocpN/utc_tai_offset
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Date: September 2021
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Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
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Description: (RW) The DCF and IRIG output signals are in UTC, while the
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TimeCard operates on TAI. This attribute allows setting the
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offset in seconds, which is added to the TAI timebase for
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these formats.
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The offset may be changed by writing an unsigned integer.
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