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+</svg>
--- /dev/null
+.. BSD LICENSE
+ Copyright(c) 2015 Intel Corporation. All rights reserved.
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions
+ are met:
+
+ * Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in
+ the documentation and/or other materials provided with the
+ distribution.
+ * Neither the name of Intel Corporation nor the names of its
+ contributors may be used to endorse or promote products derived
+ from this software without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+PTP Client Sample Application
+=============================
+
+The PTP (Precision Time Protocol) client sample application is a simple
+example of using the DPDK IEEE1588 API to communicate with a PTP master clock
+to synchronize the time on the NIC and, optionally, on the Linux system.
+
+Note, PTP is a time syncing protocol and cannot be used within DPDK as a
+time-stamping mechanism. See the following for an explanation of the protocol:
+`Precision Time Protocol
+<https://en.wikipedia.org/wiki/Precision_Time_Protocol>`_.
+
+
+Limitations
+-----------
+
+The PTP sample application is intended as a simple reference implementation of
+a PTP client using the DPDK IEEE1588 API.
+In order to keep the application simple the following assumptions are made:
+
+* The first discovered master is the master for the session.
+* Only L2 PTP packets are supported.
+* Only the PTP v2 protocol is supported.
+* Only the slave clock is implemented.
+
+
+How the Application Works
+-------------------------
+
+.. _figure_ptpclient_highlevel:
+
+.. figure:: img/ptpclient.*
+
+ PTP Synchronization Protocol
+
+The PTP synchronization in the sample application works as follows:
+
+* Master sends *Sync* message - the slave saves it as T2.
+* Master sends *Follow Up* message and sends time of T1.
+* Slave sends *Delay Request* frame to PTP Master and stores T3.
+* Master sends *Delay Response* T4 time which is time of received T3.
+
+The adjustment for slave can be represented as:
+
+ adj = -[(T2-T1)-(T4 - T3)]/2
+
+If the command line parameter ``-T 1`` is used the application also
+synchronizes the PTP PHC clock with the Linux kernel clock.
+
+
+Compiling the Application
+-------------------------
+
+To compile the application, export the path to the DPDK source tree and edit
+the ``config/common_linuxapp`` configuration file to enable IEEE1588:
+
+.. code-block:: console
+
+ export RTE_SDK=/path/to/rte_sdk
+
+ # Edit common_linuxapp and set the following options:
+ CONFIG_RTE_LIBRTE_IEEE1588=y
+
+Set the target, for example:
+
+.. code-block:: console
+
+ export RTE_TARGET=x86_64-native-linuxapp-gcc
+
+See the *DPDK Getting Started* Guide for possible ``RTE_TARGET`` values.
+
+Build the application as follows:
+
+.. code-block:: console
+
+ # Recompile DPDK.
+ make install T=$RTE_TARGET
+
+ # Compile the application.
+ cd ${RTE_SDK}/examples/ptpclient
+ make
+
+
+Running the Application
+-----------------------
+
+To run the example in a ``linuxapp`` environment:
+
+.. code-block:: console
+
+ ./build/ptpclient -c 2 -n 4 -- -p 0x1 -T 0
+
+Refer to *DPDK Getting Started Guide* for general information on running
+applications and the Environment Abstraction Layer (EAL) options.
+
+* ``-p portmask``: Hexadecimal portmask.
+* ``-T 0``: Update only the PTP slave clock.
+* ``-T 1``: Update the PTP slave clock and synchronize the Linux Kernel to the PTP clock.
+
+
+Code Explanation
+----------------
+
+The following sections provide an explanation of the main components of the
+code.
+
+All DPDK library functions used in the sample code are prefixed with ``rte_``
+and are explained in detail in the *DPDK API Documentation*.
+
+
+The Main Function
+~~~~~~~~~~~~~~~~~
+
+The ``main()`` function performs the initialization and calls the execution
+threads for each lcore.
+
+The first task is to initialize the Environment Abstraction Layer (EAL). The
+``argc`` and ``argv`` arguments are provided to the ``rte_eal_init()``
+function. The value returned is the number of parsed arguments:
+
+.. code-block:: c
+
+ int ret = rte_eal_init(argc, argv);
+ if (ret < 0)
+ rte_exit(EXIT_FAILURE, "Error with EAL initialization\n");
+
+And than we parse application specific arguments
+
+.. code-block:: c
+
+ argc -= ret;
+ argv += ret;
+
+ ret = ptp_parse_args(argc, argv);
+ if (ret < 0)
+ rte_exit(EXIT_FAILURE, "Error with PTP initialization\n");
+
+The ``main()`` also allocates a mempool to hold the mbufs (Message Buffers)
+used by the application:
+
+.. code-block:: c
+
+ mbuf_pool = rte_mempool_create("MBUF_POOL",
+ NUM_MBUFS * nb_ports,
+ MBUF_SIZE,
+ MBUF_CACHE_SIZE,
+ sizeof(struct rte_pktmbuf_pool_private),
+ rte_pktmbuf_pool_init, NULL,
+ rte_pktmbuf_init, NULL,
+ rte_socket_id(),
+ 0);
+
+Mbufs are the packet buffer structure used by DPDK. They are explained in
+detail in the "Mbuf Library" section of the *DPDK Programmer's Guide*.
+
+The ``main()`` function also initializes all the ports using the user defined
+``port_init()`` function with portmask provided by user:
+
+.. code-block:: c
+
+ for (portid = 0; portid < nb_ports; portid++)
+ if ((ptp_enabled_port_mask & (1 << portid)) != 0) {
+
+ if (port_init(portid, mbuf_pool) == 0) {
+ ptp_enabled_ports[ptp_enabled_port_nb] = portid;
+ ptp_enabled_port_nb++;
+ } else {
+ rte_exit(EXIT_FAILURE, "Cannot init port %"PRIu8 "\n",
+ portid);
+ }
+ }
+
+
+Once the initialization is complete, the application is ready to launch a
+function on an lcore. In this example ``lcore_main()`` is called on a single
+lcore.
+
+.. code-block:: c
+
+ lcore_main();
+
+The ``lcore_main()`` function is explained below.
+
+
+The Lcores Main
+~~~~~~~~~~~~~~~
+
+As we saw above the ``main()`` function calls an application function on the
+available lcores.
+
+The main work of the application is done within the loop:
+
+.. code-block:: c
+
+ for (portid = 0; portid < ptp_enabled_port_nb; portid++) {
+
+ portid = ptp_enabled_ports[portid];
+ nb_rx = rte_eth_rx_burst(portid, 0, &m, 1);
+
+ if (likely(nb_rx == 0))
+ continue;
+
+ if (m->ol_flags & PKT_RX_IEEE1588_PTP)
+ parse_ptp_frames(portid, m);
+
+ rte_pktmbuf_free(m);
+ }
+
+Packets are received one by one on the RX ports and, if required, PTP response
+packets are transmitted on the TX ports.
+
+If the offload flags in the mbuf indicate that the packet is a PTP packet then
+the packet is parsed to determine which type:
+
+.. code-block:: c
+
+ if (m->ol_flags & PKT_RX_IEEE1588_PTP)
+ parse_ptp_frames(portid, m);
+
+
+All packets are freed explicitly using ``rte_pktmbuf_free()``.
+
+The forwarding loop can be interrupted and the application closed using
+``Ctrl-C``.
+
+
+PTP parsing
+~~~~~~~~~~~
+
+The ``parse_ptp_frames()`` function processes PTP packets, implementing slave
+PTP IEEE1588 L2 functionality.
+
+.. code-block:: c
+
+ void
+ parse_ptp_frames(uint8_t portid, struct rte_mbuf *m) {
+ struct ptp_header *ptp_hdr;
+ struct ether_hdr *eth_hdr;
+ uint16_t eth_type;
+
+ eth_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
+ eth_type = rte_be_to_cpu_16(eth_hdr->ether_type);
+
+ if (eth_type == PTP_PROTOCOL) {
+ ptp_data.m = m;
+ ptp_data.portid = portid;
+ ptp_hdr = (struct ptp_header *)(rte_pktmbuf_mtod(m, char *)
+ + sizeof(struct ether_hdr));
+
+ switch (ptp_hdr->msgtype) {
+ case SYNC:
+ parse_sync(&ptp_data);
+ break;
+ case FOLLOW_UP:
+ parse_fup(&ptp_data);
+ break;
+ case DELAY_RESP:
+ parse_drsp(&ptp_data);
+ print_clock_info(&ptp_data);
+ break;
+ default:
+ break;
+ }
+ }
+ }
+
+There are 3 types of packets on the RX path which we must parse to create a minimal
+implementation of the PTP slave client:
+
+* SYNC packet.
+* FOLLOW UP packet
+* DELAY RESPONSE packet.
+
+When we parse the *FOLLOW UP* packet we also create and send a *DELAY_REQUEST* packet.
+Also when we parse the *DELAY RESPONSE* packet, and all conditions are met we adjust the PTP slave clock.
git.droids-corp.org / dpdk.git / commitdiff
