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linux/Documentation/ABI/testing/sysfs-timecard
Jonathan Lemon ff1d56cb26 docs: ABI: Document new timecard sysfs nodes. 
Add sysfs nodes for the frequency generator and signal counters.

Update SMA selector lists for these, and also add the new
'None', 'VCC' 'GND' selectors.

Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-03-11 11:54:45 +00:00

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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
TS3 signal is sent to timestamper 3
TS4 signal is sent to timestamper 4
IRIG signal is sent to the IRIG-B module
DCF signal is sent to the DCF module
FREQ1 signal is sent to frequency counter 1
FREQ2 signal is sent to frequency counter 2
FREQ3 signal is sent to frequency counter 3
FREQ4 signal is sent to frequency counter 4
None signal input is disabled
===== ================================================
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
GNSS1 output PPS is from the first 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
GEN1 output is from frequency generator 1
GEN2 output is from frequency generator 2
GEN3 output is from frequency generator 3
GEN4 output is from frequency generator 4
GND output is GND
VCC output is VCC
===== ================================================
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/clock_status_drift
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RO) Contains the current drift value used by the firmware
for internal disciplining of the atomic clock.
What: /sys/class/timecard/ocpN/clock_status_offset
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RO) Contains the current offset value used by the firmware
for internal disciplining of the atomic clock.
What: /sys/class/timecard/ocpN/freqX
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RO) Optional directory containing the sysfs nodes for
frequency counter <X>.
What: /sys/class/timecard/ocpN/freqX/frequency
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RO) Contains the measured frequency over the specified
measurement period.
What: /sys/class/timecard/ocpN/freqX/seconds
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RW) Specifies the number of seconds from 0-255 that the
frequency should be measured over. Write 0 to disable.
What: /sys/class/timecard/ocpN/genX
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RO) Optional directory containing the sysfs nodes for
frequency generator <X>.
What: /sys/class/timecard/ocpN/genX/duty
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RO) Specifies the signal duty cycle as a percentage from 1-99.
What: /sys/class/timecard/ocpN/genX/period
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RO) Specifies the signal period in nanoseconds.
What: /sys/class/timecard/ocpN/genX/phase
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RO) Specifies the signal phase offset in nanoseconds.
What: /sys/class/timecard/ocpN/genX/polarity
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RO) Specifies the signal polarity, either 1 or 0.
What: /sys/class/timecard/ocpN/genX/running
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RO) Either 0 or 1, showing if the signal generator is running.
What: /sys/class/timecard/ocpN/genX/start
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RO) Shows the time in <sec>.<nsec> that the signal generator
started running.
What: /sys/class/timecard/ocpN/genX/signal
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RW) Used to start the signal generator, and summarize
the current status.
The signal generator may be started by writing the signal
period, followed by the optional signal values. If the
optional values are not provided, they default to the current
settings, which may be obtained from the other sysfs nodes.
period [duty [phase [polarity]]]
echo 500000000 > signal # 1/2 second period
echo 1000000 40 100 > signal
echo 0 > signal # turn off generator
Period and phase are specified in nanoseconds. Duty cycle is
a percentage from 1-99. Polarity is 1 or 0.
Reading this node will return:
period duty phase polarity start_time
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/tod_correction
Date: March 2022
Contact: Jonathan Lemon <jonathan.lemon@gmail.com>
Description: (RW) The incoming GNSS signal is in UTC time, and the NMEA
format messages do not provide a TAI offset. This sets the
correction value for the incoming time.
If UBX_LS is enabled, this should be 0, and the offset is
taken from the UBX-NAV-TIMELS message.
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.
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