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.
user space: ^ ^ | SO_TIMESTAMPING new flag: | Packets with | SOF_TIMESTAMPING_BIND_PHC | TX/RX HW timestamps v v +--------------------------------------------+ sock: | sock (new member sk_bind_phc) | +--------------------------------------------+ ^ ^ | ethtool_op_get_phc_vclocks | Convert HW timestamps | | to sk_bind_phc v v +--------------+--------------+--------------+ vclock: | ptp1 | ptp2 | ptpN | +--------------+--------------+--------------+ pclock: | ptp0 free running | +--------------------------------------------+
The block diagram may explain how it works. Besides the PTP virtual clocks, the packet HW timestamp converting to the bound PHC is also done in sock driver. For user space, PTP virtual clocks can be created via sysfs, and extended SO_TIMESTAMPING API (new flag SOF_TIMESTAMPING_BIND_PHC) can be used to bind one PTP virtual clock for timestamping.
The test tool timestamping.c (together with linuxptp phc_ctl tool) can be used to verify:
# echo 4 > /sys/class/ptp/ptp0/n_vclocks [ 129.399472] ptp ptp0: new virtual clock ptp2 [ 129.404234] ptp ptp0: new virtual clock ptp3 [ 129.409532] ptp ptp0: new virtual clock ptp4 [ 129.413942] ptp ptp0: new virtual clock ptp5 [ 129.418257] ptp ptp0: guarantee physical clock free running # # phc_ctl /dev/ptp2 set 10000 # phc_ctl /dev/ptp3 set 20000 # # timestamping eno0 2 SOF_TIMESTAMPING_TX_HARDWARE SOF_TIMESTAMPING_RAW_HARDWARE SOF_TIMESTAMPING_BIND_PHC # timestamping eno0 2 SOF_TIMESTAMPING_RX_HARDWARE SOF_TIMESTAMPING_RAW_HARDWARE SOF_TIMESTAMPING_BIND_PHC # timestamping eno0 3 SOF_TIMESTAMPING_TX_HARDWARE SOF_TIMESTAMPING_RAW_HARDWARE SOF_TIMESTAMPING_BIND_PHC # timestamping eno0 3 SOF_TIMESTAMPING_RX_HARDWARE SOF_TIMESTAMPING_RAW_HARDWARE SOF_TIMESTAMPING_BIND_PHC
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. Changes for v3: - Supported PTP virtual clock in default in PTP driver. - Protected concurrency of ptp->num_vclocks accessing. - Supported PHC vclocks query via ethtool. - Extended SO_TIMESTAMPING API for PHC binding. - Converted HW timestamps to PHC bound, instead of previous binding domain value to PHC idea. - Other minor fixes.
Yangbo Lu (10): ptp: add ptp virtual clock driver framework ptp: support ptp physical/virtual clocks conversion ptp: track available ptp vclocks information ptp: add kernel API ptp_get_vclocks_index() ethtool: add a new command for getting PHC virtual clocks ptp: add kernel API ptp_convert_timestamp() net: sock: extend SO_TIMESTAMPING for PHC binding net: socket: support hardware timestamp conversion to PHC bound selftests/net: timestamping: support binding PHC MAINTAINERS: add entry for PTP virtual clock driver
Documentation/ABI/testing/sysfs-ptp | 13 ++ MAINTAINERS | 7 + drivers/ptp/Makefile | 2 +- drivers/ptp/ptp_clock.c | 27 ++- drivers/ptp/ptp_private.h | 34 ++++ drivers/ptp/ptp_sysfs.c | 95 +++++++++ drivers/ptp/ptp_vclock.c | 212 +++++++++++++++++++++ include/linux/ethtool.h | 2 + include/linux/ptp_clock_kernel.h | 29 ++- include/net/sock.h | 8 +- include/uapi/linux/ethtool.h | 14 ++ include/uapi/linux/ethtool_netlink.h | 15 ++ include/uapi/linux/net_tstamp.h | 17 +- include/uapi/linux/ptp_clock.h | 5 + net/core/sock.c | 65 ++++++- net/ethtool/Makefile | 2 +- net/ethtool/common.c | 24 +++ net/ethtool/common.h | 2 + net/ethtool/ioctl.c | 27 +++ net/ethtool/netlink.c | 10 + net/ethtool/netlink.h | 2 + net/ethtool/phc_vclocks.c | 86 +++++++++ net/mptcp/sockopt.c | 10 +- net/socket.c | 19 +- tools/testing/selftests/net/timestamping.c | 62 ++++-- 25 files changed, 750 insertions(+), 39 deletions(-) create mode 100644 drivers/ptp/ptp_vclock.c create mode 100644 net/ethtool/phc_vclocks.c
base-commit: 89212e160b81e778f829b89743570665810e3b13