nvidia xavier nx平台上精确时间协议(PTP)调试记录1_专栏

1. 前言

NX是否支持协议:
ieee802.1时间敏感组网(TSN)?
IEEE1588v2一步精确时间协议(PTP)?

NX应该像Xavier一样支持PTP。

2.linuxptp工具调试

 ethtool -T eth0
Time stamping parameters for eth0:
Capabilities:
    hardware-transmit     (SOF_TIMESTAMPING_TX_HARDWARE)
    software-transmit     (SOF_TIMESTAMPING_TX_SOFTWARE)
    hardware-receive      (SOF_TIMESTAMPING_RX_HARDWARE)
    software-receive      (SOF_TIMESTAMPING_RX_SOFTWARE)
    software-system-clock (SOF_TIMESTAMPING_SOFTWARE)
    hardware-raw-clock    (SOF_TIMESTAMPING_RAW_HARDWARE)
PTP Hardware Clock: 0
Hardware Transmit Timestamp Modes:
    off                   (HWTSTAMP_TX_OFF)
    on                    (HWTSTAMP_TX_ON)
Hardware Receive Filter Modes:
    none                  (HWTSTAMP_FILTER_NONE)
    ptpv1-l4-sync         (HWTSTAMP_FILTER_PTP_V1_L4_SYNC)
    ptpv1-l4-delay-req    (HWTSTAMP_FILTER_PTP_V1_L4_DELAY_REQ)
    ptpv2-l4-sync         (HWTSTAMP_FILTER_PTP_V2_L4_SYNC)
    ptpv2-l4-delay-req    (HWTSTAMP_FILTER_PTP_V2_L4_DELAY_REQ)
    ptpv2-l2-sync         (HWTSTAMP_FILTER_PTP_V2_L2_SYNC)
    ptpv2-l2-delay-req    (HWTSTAMP_FILTER_PTP_V2_L2_DELAY_REQ)
    ptpv2-event           (HWTSTAMP_FILTER_PTP_V2_EVENT)

安装linuxptp

 git clone git://git.code.sf.net/p/linuxptp/code linuxptp
   cd linuxptp/
   make -j6
  sudo make install

运行

 sudo ptp4l -i eth0 -m -S
ptp4l[69457.930]: port 1: INITIALIZING to LISTENING on INIT_COMPLETE
ptp4l[69457.931]: port 0: INITIALIZING to LISTENING on INIT_COMPLETE
ptp4l[69464.849]: port 1: LISTENING to MASTER on ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES
ptp4l[69464.850]: selected local clock 48b02d.fffe.05a79e as best master
ptp4l[69464.850]: port 1: assuming the grand master role

3.参考PTP测试步骤

Host side
ifconfig eth0 down
ifconfig eth0 up
ifconfig eth0 0.0.0.0
ip addr add 10.0.0.1/24 dev eth0
ip link set dev eth0 up
timedatectl set-ntp false
date 010100002018
phc_ctl /dev/ptp0 set
phc_ctl /dev/ptp0 get
ptp4l -f gPTP.cfg -i eth0 -p /dev/ptp0 -m
DUT side
ifconfig eth0 down
ifconfig eth0 up
ifconfig eth0 0.0.0.0
ip addr add 10.0.0.2/24 dev eth0
ip link set dev eth0 up
timedatectl set-ntp false
phc_ctl /dev/ptp0 get
ptp4l -f gPTP.cfg -i eth0 -p /dev/ptp0 -s -m

NX PPS支持似乎需要重新构建内核，以便将PPS设备输出添加到ptp实现中。
默认的内核似乎具有PPS。

nx2:~/linuxptp$ zcat /proc/config.gz | grep -i pps
# PPS support
CONFIG_PPS=y
CONFIG_PPS_DEBUG=y
# PPS clients support
# CONFIG_PPS_CLIENT_KTIMER is not set
# CONFIG_PPS_CLIENT_LDISC is not set
CONFIG_PPS_CLIENT_GPIO=y
# PPS generators support
# CONFIG_NVPPS is not set

在重新构建内核并添加PPS- ktimer模块后，
是否可能使用例如simpleRT2K设备[或ublox F9t] PPS来提高PTP实现的精度?

4. NX平台创建PPS节点

创建一个设备树绑定来设置与pps-gpio驱动程序相关联的gpio。
类似于这个来自内核文档的例子…

pps {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_pps>;

        gpios = <&gpio1 26 GPIO_ACTIVE_HIGH>;
        assert-falling-edge;

        echo-gpios = <&gpio1 27 GPIO_ACTIVE_HIGH>;
        echo-active-ms = <100>;

        compatible = "pps-gpio";
    };

/dev/ptp0已经存在，但是没有与之关联的PPS源(因为没有PPS设备)。
一旦完成上述绑定，就会自动显示/dev/pps0设备并由ptp0使用。
然后外部设备的PPS输出将连接到创建绑定时选择的GPIO
使用任何必要的电压转换。

5. 参考Xavier平台用GPIO作为PPS接口

Xavier在硬件上没有支持该功能(PPS信号)的引脚。
您可以使用GPIO作为PPS接口，对模拟的PPS信号进行软件修改。
内核中已经启用了CONFIG_PPS和CONFIG_PPS_CLIENT_GPIO。
请在dtb内核中添加设备树节点，如下所示:

pps {
gpios = <&tegra_aon_gpio TEGRA194_AON_GPIO(AA, 0) GPIO_ACTIVE_LOW>;  //// here use gpio for the pin in which you want pps signal.
compatible = "pps-gpio";
assert-falling-edge;
status = "okay";
};

在系统引导之后，您将看到用于PPS的sysfs节点。