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Message-Id: <20210521043619.44694-1-yangbo.lu@nxp.com>
Date: Fri, 21 May 2021 12:36:12 +0800
From: Yangbo Lu <yangbo.lu@....com>
To: netdev@...r.kernel.org
Cc: Yangbo Lu <yangbo.lu@....com>,
"David S . Miller" <davem@...emloft.net>,
Richard Cochran <richardcochran@...il.com>,
Claudiu Manoil <claudiu.manoil@....com>,
Jakub Kicinski <kuba@...nel.org>
Subject: [net-next, v2, 0/7] ptp: support virtual clocks for multiple
Current PTP driver exposes one PTP device to user which binds network
interface/interfaces to provide timestamping. Actually we have a way
utilizing timecounter/cyclecounter to virtualize any number of PTP
clocks based on a same free running physical clock for using.
The purpose of having multiple PTP virtual clocks is for user space
to directly/easily use them for multiple domains synchronization.
+------------------------------+
MAC driver: | rx/tx PTP packet |
+------------------------------+
^
| Match vclock via domain value
| Convert HW timestamp to domain time
v
+--------------+--------------+--------------+
vclock: | ptp1 domain1 | ptp2 domain2 | ptpN domainN |
+--------------+--------------+--------------+
pclock: | ptp0 free running |
+--------------------------------------------+
The block diagram may explain how it works. Besides the PTP virtual
clocks, the PTP packet HW timestamp converting to domain time is also
done in kernel.
An example to use it:
Run two ptp4l jobs on each of two boards for domain 1 and 2 synchronziation.
Board1:
# echo 2 > /sys/class/ptp/ptp0/num_vclocks
[ 282.230432] ptp ptp0: new virtual clock ptp2
[ 282.235211] ptp ptp0: new virtual clock ptp3
[ 282.240354] ptp ptp0: guarantee physical clock free running
# echo 1 > /sys/class/ptp/ptp2/domain
# echo 2 > /sys/class/ptp/ptp3/domain
#
# ptp4l -i eno0 -p/dev/ptp2 -m --domainNumber=1 --priority1=127 > domain1-master.log 2>&1 &
# ptp4l -i eno0 -p/dev/ptp3 -m --domainNumber=2 --priority1=128 > domain2-slave.log 2>&1 &
Board2:
# echo 2 > /sys/class/ptp/ptp0/num_vclocks
[ 259.619382] ptp ptp0: new virtual clock ptp2
[ 259.624140] ptp ptp0: new virtual clock ptp3
[ 259.629315] ptp ptp0: guarantee physical clock free running
# echo 1 > /sys/class/ptp/ptp2/domain
# echo 2 > /sys/class/ptp/ptp3/domain
#
# ptp4l -i eno0 -p/dev/ptp2 -m --domainNumber=1 --priority1=128 > domain1-slave.log 2>&1 &
# ptp4l -i eno0 -p/dev/ptp3 -m --domainNumber=2 --priority1=127 > domain2-master.log 2>&1 &
Physical clock is guaranteed to stay free running when virtual clocks
are created. To back use physical clock,
# echo 0 > /sys/class/ptp/ptp0/num_vclocks
[ 531.249944] ptp ptp0: delete virtual clock ptp3
[ 531.254971] ptp ptp0: delete virtual clock ptp2
[ 531.259976] ptp ptp0: only physical clock in use now
How the patch-set affect current ptp drivers/function:
- For current drivers, no impact on all existing function.
- For drivers adapted to use it in the future, no impact on all
existing function unless configuring value to num_vclocks in
sysfs to convert to using virtual clocks.
- For drivers adapted to use it with virtual clocks in using
- Manual configurations are required for domain value in sysfs.
- Manual configurations are required for application to specify
right ptp device for domain on which the application will run.
Note,
- Physical clock is guaranteed to stay free running. Operation on it
returns error.
- If domain value of application has no PTP clock matched, the
original HW timestamp will be used.
How to adapt drivers to use the feature:
- During normally registering PTP clock for physical clock with
ptp_clock_info, just fill the new member vclock_cc which contains
cyclecounter info for virtual clock.
- Timestamp conversion to domain time need to be done in MAC driver.
When get HW timestamp, parse PTP packet domain value and convert
timestamp to domain time by calling API ptp_clock_domain_tstamp(),
before submitting to upper stack.
TODO:
- PTP physical clock and its timestamping capabilities is still
binding to network interface/interfaces through ethtool_ts_info.
New way is needed to support querying all PTP virtual clocks
and their timestamping capabilities. Making application to use
PTP virtual clocks dynamically is a direction.
- PTP packet parsing for domain value and one-step sync (not related
to this patch-set) is common used. Make such functions common.
Changes for v2:
- Converted to num_vclocks for creating virtual clocks.
- Guranteed physical clock free running when using virtual
clocks.
- Fixed build warning.
- Updated copyright.
Yangbo Lu (7):
ptp: add ptp virtual clock driver framework
ptp: support ptp physical/virtual clocks conversion
ptp: support domains and timestamp conversion
ptp_qoriq: export ptp clock reading function for cyclecounter
enetc_ptp: support ptp virtual clock
enetc: store ptp device pointer
enetc: support PTP domain timestamp conversion
Documentation/ABI/testing/sysfs-ptp | 25 +++
MAINTAINERS | 6 +
drivers/net/ethernet/freescale/enetc/enetc.c | 39 +++-
drivers/net/ethernet/freescale/enetc/enetc.h | 3 +-
.../net/ethernet/freescale/enetc/enetc_pf.c | 14 +-
.../net/ethernet/freescale/enetc/enetc_ptp.c | 13 +-
.../net/ethernet/freescale/enetc/enetc_vf.c | 14 +-
drivers/ptp/Makefile | 2 +-
drivers/ptp/ptp_clock.c | 12 ++
drivers/ptp/ptp_private.h | 42 +++++
drivers/ptp/ptp_qoriq.c | 16 ++
drivers/ptp/ptp_sysfs.c | 134 +++++++++++++
drivers/ptp/ptp_vclock.c | 176 ++++++++++++++++++
include/linux/fsl/ptp_qoriq.h | 3 +-
include/linux/ptp_clock_kernel.h | 57 +++++-
15 files changed, 545 insertions(+), 11 deletions(-)
create mode 100644 drivers/ptp/ptp_vclock.c
base-commit: 86544c3de6a2185409c5a3d02f674ea223a14217
--
2.25.1
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