nuttx-apps/netutils/ptpd/Kconfig
Daniel P. Carvalho 585db4b657 netutils/ptpd: Add ingress latency compensation for RX timestamps.
The MAC latches a hardware receive timestamp later than the frame
reaches the wire, because of the PHY and the clock domain crossing.
This fixed delay is the ingressLatency port parameter of IEEE 1588 and
shows up as a constant phase error between the local and the master
clock.

Subtract the configured latency from every hardware receive timestamp
in ptp_getrxtime(), the single place where they enter the daemon, so
Sync, Delay_Resp and the peer delay messages are all corrected.

- Add CONFIG_NETUTILS_PTPD_INGRESS_LATENCY_NS (default 0, which applies
  no compensation).
- Add the -I option to override it at run time.
- Add ingress_latency_ns to struct ptpd_config_s.

Software timestamps are not affected.

Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Daniel P. Carvalho <danieloak@gmail.com>
2026-09-24 11:07:31 +08:00

242 lines
7.6 KiB
Text

#
# For a description of the syntax of this configuration file,
# see the file kconfig-language.txt in the NuttX tools repository.
#
config NETUTILS_PTPD
bool "PTPD client/server"
default n
depends on NET_IPv4
depends on NET_IGMP
depends on NET_UDP || NET_PKT
---help---
Build a minimal implementation of IEEE-1588 precision time protocol.
Uses system gettimeofday() and adjtime() calls to synchronize clock
with a master clock through network, or to provide a master clock to
other systems.
if NETUTILS_PTPD
config NETUTILS_PTPD_STACKSIZE
int "PTP daemon stack stack size"
default DEFAULT_TASK_STACKSIZE
config NETUTILS_PTPD_SERVERPRIO
int "PTP daemon priority"
default 100
config NETUTILS_PTPD_DOMAIN
int "PTP domain selection"
default 0
range 0 127
---help---
Set PTP domain to participate in. Default domain is 0, other domains
can be used to isolate reference clocks from each other.
config NETUTILS_PTPD_PRIORITY1
int "PTP server priority1"
default 128
range 0 255
---help---
Set clock priority to announce when acting as a PTP server.
Lower value is higher priority.
A higher priority1 clock will be selected without regard to announced
clock quality fields.
Refer to Best Master Clock algorithm in IEEE-1588 for details.
config NETUTILS_PTPD_PRIORITY2
int "PTP server priority2"
default 128
range 0 255
---help---
Set clock subpriority to announce when acting as a PTP server.
This will distinguish between two clocks that are equivalent in
priority1, class and accuracy values.
Lower value is higher priority.
config NETUTILS_PTPD_CLASS
int "PTP server class"
default 248
range 0 255
---help---
Set master clock class to announce when acting as a PTP server.
Lower value means higher quality clock source.
248 is the default for unknown class.
config NETUTILS_PTPD_ACCURACY
int "PTP server accuracy"
default 254
range 0 255
---help---
Set master clock accuracy to announce when acting as a PTP server.
Logarithmic scale is defined in IEEE-1588:
32: +- 25 ns
33: +- 100 ns
34: +- 250 ns
35: +- 1 us
36: +- 2.5 us
37: +- 10 us
38: +- 25 us
39: +- 100 us
40: +- 250 us
41: +- 1 ms
42: +- 2.5 ms
43: +- 10 ms
44: +- 25 ms
45: +- 100 ms
46: +- 250 ms
47: +- 1 s
48: +- 10 s
49: +- more than 10 s
254: Unknown
config NETUTILS_PTPD_CLOCKSOURCE
int "PTP server clock source type"
default 160
range 0 255
---help---
Set clock source type to announce when acting as a PTP server.
Common values:
32: GPS
64: PTP
80: NTP
144: Other
160: Internal oscillator
config NETUTILS_PTPD_SYNC_INTERVAL_MSEC
int "PTP server sync transmit interval (ms)"
default 1000
---help---
How often to transmit sync packets in server mode.
config NETUTILS_PTPD_ANNOUNCE_INTERVAL_MSEC
int "PTP server announce transmit interval (ms)"
default 10000
---help---
How often to transmit announce packets in server mode.
config NETUTILS_PTPD_TWOSTEP_SYNC
bool "PTP server sends two-step synchronization packets"
default y
---help---
If enabled, sends a follow-up packet after every sync packet.
This helps compensate for the time taken to initiate the transmission.
config NETUTILS_PTPD_DELAYRESP_INTERVAL
int "PTP server suggested interval of delay requests"
range 0 255
default 4
---help---
When responding to a delay request, the server can inform the client
how often it should test path delay. This is done using header field
logMessageInterval. The delay will be 2^N seconds.
Default value 4 results in 16 second interval.
config NETUTILS_PTPD_TIMEOUT_MS
int "PTP client timeout for changing clock source (ms)"
default 60000
---help---
If no packets are being received from currently chosen clock source,
fall back to next best clock source after this many seconds.
config NETUTILS_PTPD_SETTIME_THRESHOLD_MS
int "PTP client threshold for changing system time (ms)"
default 1000
---help---
If difference between local and remote clock exceeds this threshold,
time is reset with settimeofday() instead of changing the rate with
adjtime().
config NETUTILS_PTPD_ADJTIME_THRESHOLD_NS
int "PTP client threshold for using accumulated ppb to adjust system time (ns)"
default 500
---help---
If difference between local and remote clock exceeds this threshold,
the PTP client can utilize current ppb instead of accumulated ppb to
accelerate system time adjustment.
config NETUTILS_PTPD_MULTICAST_TIMEOUT_MS
int "PTP client timeout to rejoin multicast group (ms)"
default 30000
---help---
If no PTP multicast packets are being received, attempt to rejoin the
multicast group. This can be necessary if network topology changes, or
depending on hardware, after some error recovery events.
Set to 0 to disable.
config NETUTILS_PTPD_DRIFT_AVERAGE_S
int "PTP client clock drift rate averaging time (s)"
default 600
range 10 86400
---help---
Clock drift rate is averaged over this time pediod. Larger value
gives more stable estimate but reacts slower to crystal oscillator speed
changes (such as caused by temperature changes).
config NETUTILS_PTPD_MAX_DRIFT_PPB
int "PTP client maximum plausible clock drift rate (ppb)"
default 500000
range 1000 20000000
---help---
A single drift-rate sample computed between two consecutive sync
updates is discarded (the previous averaged drift_ppb is kept
unchanged) if its magnitude exceeds this bound. Real crystal
oscillators drift by at most a few hundred ppm (hundreds of
thousands of ppb), so this catches bogus samples caused by an
abnormally short or long measurement interval - e.g. right after
a clock source outage/reconnect, or a burst of closely spaced
sync packets following packet loss - before they corrupt the
long-term drift_ppb average and get applied to the hardware.
This is intentionally much tighter than
CLOCK_ADJTIME_SLEWLIMIT_PPM, which bounds how fast a correction
may be applied rather than how large a real drift measurement
can plausibly be.
config NETUTILS_PTPD_MAX_PATH_DELAY_NS
int "PTP client maximum path delay (ns)"
default 100000
range 1 1000000000
---help---
Measured path delay longer than this is ignored. Delay requests are
also not transmitted until clock synchronization is better than this.
config NETUTILS_PTPD_DELAYREQ_AVGCOUNT
int "PTP client path delay averaging count"
default 100
---help---
Measured path delay is averaged over this many samples.
config NETUTILS_PTPD_STATUSFILE
string "PTP daemon status file path"
default "/tmp/ptpd.status"
---help---
Path where the PTP daemon writes its binary status file
when signaled with SIGUSR1. The ptpd_status() API reads
this file to retrieve daemon state without requiring shared
memory, making it work across all build modes (Flat,
Protected, Kernel). Written atomically via temp + rename.
config NETUTILS_PTPD_INGRESS_LATENCY_NS
int "PTP hardware receive timestamp latency (ns)"
default 0
range -1000000 1000000
---help---
Fixed delay, in nanoseconds, between a frame reaching the wire
reference plane and the moment the MAC latches its hardware
receive timestamp. This is the ingressLatency port parameter of
IEEE 1588: the PHY and the MAC clock-domain crossing make the
timestamp point lag the true arrival of the frame.
The latency is subtracted from every hardware receive timestamp,
so a positive value moves the timestamps earlier. It has no
effect with software timestamping. It can be overridden at
run time with the -I option.
The value depends on the PHY and board and has to be measured,
for example by comparing a physical PPS output against a
reference. The default of 0 applies no compensation.
endif # NETUTILS_PTPD