Lines Matching +full:single +full:- +full:phase
2 SocketCAN - Controller Area Network
20 .. _socketcan-motivation:
29 functionality. Usually, there is only a hardware-specific device
32 Queueing of frames and higher-level transport protocols like ISO-TP
34 character-device implementations support only one single process to
47 protocol family module and also vice-versa. Also, the protocol family
57 communicate using a specific transport protocol, e.g. ISO-TP, just
60 CAN-IDs, frames, etc.
62 Similar functionality visible from user-space could be provided by a
74 * **Abstraction:** In most existing character-device implementations, the
75 hardware-specific device driver for a CAN controller directly
83 application on the one hand, and a interface for hardware-specific
103 .. _socketcan-concept:
108 As described in :ref:`socketcan-motivation` the main goal of SocketCAN is to
111 TCP/IP and ethernet networking, the CAN bus is a broadcast-only(!)
112 medium that has no MAC-layer addressing like ethernet. The CAN-identifier
113 (can_id) is used for arbitration on the CAN-bus. Therefore the CAN-IDs
114 have to be chosen uniquely on the bus. When designing a CAN-ECU
115 network the CAN-IDs are mapped to be sent by a specific ECU.
116 For this reason a CAN-ID can be treated best as a kind of source address.
119 .. _socketcan-receive-lists:
122 -------------
126 CAN-IDs from the same CAN network interface. The SocketCAN core
127 module - which implements the protocol family CAN - provides several
130 requests the (range of) CAN-IDs from the SocketCAN core that are
132 CAN-IDs can be done for specific CAN interfaces or for all(!) known
134 CAN protocol modules by the SocketCAN core (see :ref:`socketcan-core-module`).
137 filter complexity for a given use-case.
140 .. _socketcan-local-loopback1:
143 -----------------------------
156 -----------------(1)- CAN bus -(2)---------------
165 arbitration on the CAN bus the transmission of a low prio CAN-ID
171 See :ref:`socketcan-local-loopback2` for details (recommended).
175 the RT-SocketCAN group the loopback optionally may be disabled for each
176 separate socket. See sockopts from the CAN RAW sockets in :ref:`socketcan-raw-sockets`.
182 .. _socketcan-network-problem-notifications:
185 -----------------------------
225 - see :ref:`socketcan-concept`). After binding (CAN_RAW) or connecting (CAN_BCM)
234 .. code-block:: C
270 .. code-block:: C
303 .. code-block:: C
331 .. code-block:: C
358 .. code-block:: C
376 .. code-block:: C
389 .. code-block:: C
401 bitrates for the arbitration phase and the payload phase of the CAN FD frame
407 and Classical CAN frames simultaneously (see :ref:`socketcan-rawfd`).
411 .. code-block:: C
426 all structure elements can be used as-is - only the data[] becomes extended.
435 the mapping to the bus-relevant data length code (DLC), see :ref:`socketcan-can-fd-driver`.
441 .. code-block:: C
448 ----------------------
451 msg->msg_flags field may contain the following flags:
460 :ref:`socketcan-local-loopback1` and :ref:`socketcan-local-loopback2`.
465 .. _socketcan-raw-sockets:
468 ------------------------------------------------
475 - The filters are set to exactly one filter receiving everything
476 - The socket only receives valid data frames (=> no error message frames)
477 - The loopback of sent CAN frames is enabled (see :ref:`socketcan-local-loopback2`)
478 - The socket does not receive its own sent frames (in loopback mode)
485 .. _socketcan-rawfilter:
495 .. code-block:: C
504 .. code-block:: C
514 .. code-block:: C
527 .. code-block:: C
533 having this 'send only' use-case we may remove the receive list in the
539 The CAN filters are processed in per-device filter lists at CAN frame
542 filter handling when the filter subscription focusses on a single CAN ID.
549 To benefit from the optimized filters for single CAN identifiers the
555 .. code-block:: C
565 .. code-block:: C
580 As described in :ref:`socketcan-network-problem-notifications` the CAN interface driver can generat…
588 .. code-block:: C
600 (see :ref:`socketcan-local-loopback1` for details). But in some embedded use-cases
604 .. code-block:: C
616 frames' CAN-ID on this given interface to meet the multi user
622 .. code-block:: C
630 filtering as other CAN frames (see :ref:`socketcan-rawfilter`).
632 .. _socketcan-rawfd:
640 CAN_RAW_FD_FRAMES option returns the error -ENOPROTOOPT.
646 .. code-block:: C
653 .. code-block:: C
703 applied (see :ref:`socketcan-rawfilter`).
710 where the CAN_INV_FILTER flag is set in order to notch single CAN IDs or
715 -----------------------------------------------
721 such as message contents changes, packet length changes, and do time-out
736 .. code-block:: C
749 at the beginning of :ref:`socketcan-rawfd` and in the include/linux/can.h include. All
755 .. code-block:: C
880 Send reply for RTR-request (placed in op->frames[0]).
904 .. code-block:: C
925 The timer values ival1 or ival2 may be set to non-zero values at RX_SETUP.
931 is activated directly - even without a former CAN frame reception.
951 .. code-block:: C
953 /* usually used to clear CAN frame data[] - beware of endian problems! */
954 #define U64_DATA(p) (*(unsigned long long*)(p)->data)
983 .. code-block:: C
1001 ----------------------------------------------
1007 --------------------------------------------
1012 .. _socketcan-core-module:
1020 modules to subscribe needed CAN IDs (see :ref:`socketcan-receive-lists`).
1024 --------------------
1026 - **stats_timer**:
1032 - **debug**:
1037 --------------
1039 As described in :ref:`socketcan-receive-lists` the SocketCAN core uses several filter
1057 rcvlist_all - list for unfiltered entries (no filter operations)
1058 rcvlist_eff - list for single extended frame (EFF) entries
1059 rcvlist_err - list for error message frames masks
1060 rcvlist_fil - list for mask/value filters
1061 rcvlist_inv - list for mask/value filters (inverse semantic)
1062 rcvlist_sff - list for single standard frame (SFF) entries
1066 stats - SocketCAN core statistics (rx/tx frames, match ratios, ...)
1067 reset_stats - manual statistic reset
1068 version - prints SocketCAN core and ABI version (removed in Linux 5.10)
1072 --------------------------------
1082 can_rx_register - subscribe CAN frames from a specific interface
1083 can_rx_unregister - unsubscribe CAN frames from a specific interface
1084 can_send - transmit a CAN frame (optional with local loopback)
1097 - TX: Put the CAN frame from the socket buffer to the CAN controller.
1098 - RX: Put the CAN frame from the CAN controller to the socket buffer.
1105 ----------------
1108 alloc_netdev_mqs(), to automatically take care of CAN-specific setup:
1110 .. code-block:: C
1118 .. _socketcan-local-loopback2:
1121 -----------------------------
1123 As described in :ref:`socketcan-local-loopback1` the CAN network device driver should
1129 dev->flags = (IFF_NOARP | IFF_ECHO);
1133 -------------------------------
1138 controller and have to be identified as not feasible in a multi-user
1140 hardware filters could make sense in a very dedicated use-case, as a
1141 filter on driver level would affect all users in the multi-user
1151 --------------------------------
1160 $ ip -details link show can0
1172 To enable termination resistor support to a can-controller, either
1173 implement in the controller's struct can-priv::
1180 Documentation/devicetree/bindings/net/can/can-controller.yaml
1184 -----------------------------
1189 - a unique CAN Identifier (CAN ID)
1190 - the CAN bus this CAN ID is transmitted on (e.g. can0)
1203 - Create a virtual CAN network interface:
1206 - Create a virtual CAN network interface with a specific name 'vcan42':
1209 - Remove a (virtual CAN) network interface 'vcan42':
1214 ---------------------------------------
1218 configure the CAN device, like setting the bit-timing parameters, via
1224 understand how to use them. The name of the module is can-dev.ko.
1240 [ bitrate BITRATE [ sample-point SAMPLE-POINT] ] |
1241 [ tq TQ prop-seg PROP_SEG phase-seg1 PHASE-SEG1
1242 phase-seg2 PHASE-SEG2 [ sjw SJW ] ]
1244 [ dbitrate BITRATE [ dsample-point SAMPLE-POINT] ] |
1245 [ dtq TQ dprop-seg PROP_SEG dphase-seg1 PHASE-SEG1
1246 dphase-seg2 PHASE-SEG2 [ dsjw SJW ] ]
1249 [ listen-only { on | off } ]
1250 [ triple-sampling { on | off } ]
1251 [ one-shot { on | off } ]
1252 [ berr-reporting { on | off } ]
1254 [ fd-non-iso { on | off } ]
1255 [ presume-ack { on | off } ]
1256 [ cc-len8-dlc { on | off } ]
1258 [ restart-ms TIME-MS ]
1262 SAMPLE-POINT := { 0.000..0.999 }
1264 PROP-SEG := { 1..8 }
1265 PHASE-SEG1 := { 1..8 }
1266 PHASE-SEG2 := { 1..8 }
1268 RESTART-MS := { 0 | NUMBER }
1272 $ ip -details -statistics link show can0
1275 can <TRIPLE-SAMPLING> state ERROR-ACTIVE restart-ms 100
1277 tq 125 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1
1278 sja1000: tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1
1280 re-started bus-errors arbit-lost error-warn error-pass bus-off
1289 "<TRIPLE-SAMPLING>"
1291 LISTEN-ONLY, or TRIPLE-SAMPLING.
1293 "state ERROR-ACTIVE"
1294 The current state of the CAN controller: "ERROR-ACTIVE",
1295 "ERROR-WARNING", "ERROR-PASSIVE", "BUS-OFF" or "STOPPED"
1297 "restart-ms 100"
1298 Automatic restart delay time. If set to a non-zero value, a
1300 in case of a bus-off condition after the specified delay time
1303 "bitrate 125000 sample-point 0.875"
1304 Shows the real bit-rate in bits/sec and the sample-point in the
1305 range 0.000..0.999. If the calculation of bit-timing parameters
1307 bit-timing can be defined by setting the "bitrate" argument.
1308 Optionally the "sample-point" can be specified. By default it's
1309 0.000 assuming CIA-recommended sample-points.
1311 "tq 125 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1"
1312 Shows the time quanta in ns, propagation segment, phase buffer
1314 tq. They allow to define the CAN bit-timing in a hardware
1318 "sja1000: tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1 clock 8000000"
1319 Shows the bit-timing constants of the CAN controller, here the
1322 bitrate pre-scaler and the CAN system clock frequency in Hz.
1323 These constants could be used for user-defined (non-standard)
1324 bit-timing calculation algorithms in user-space.
1326 "re-started bus-errors arbit-lost error-warn error-pass bus-off"
1328 and the state changes to the error-warning, error-passive and
1329 bus-off state. RX overrun errors are listed in the "overrun"
1332 Setting the CAN Bit-Timing
1335 The CAN bit-timing parameters can always be defined in a hardware
1340 $ ip link set canX type can tq 125 prop-seg 6 \
1341 phase-seg1 7 phase-seg2 2 sjw 1
1344 recommended CAN bit-timing parameters will be calculated if the bit-
1350 standard bit-rates but may *fail* for exotic bit-rates or CAN system
1352 space and allows user-space tools to solely determine and set the
1353 bit-timing parameters. The CAN controller specific bit-timing
1357 $ ip -details link show can0
1359 sja1000: clock 8000000 tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1
1367 you *must* define proper bit-timing parameters for real CAN devices
1368 before you can start it to avoid error-prone default settings::
1372 A device may enter the "bus-off" state if too many errors occurred on
1374 bus-off recovery can be enabled by setting the "restart-ms" to a
1375 non-zero value, e.g.::
1377 $ ip link set canX type can restart-ms 100
1379 Alternatively, the application may realize the "bus-off" condition
1386 also :ref:`socketcan-network-problem-notifications`).
1389 .. _socketcan-can-fd-driver:
1392 ------------------------------------------
1395 arbitration phase and the payload phase of the CAN FD frame. Therefore a
1403 CAN frames anyway. The payload length to the bus-relevant DLC mapping is
1417 has to be set. This bitrate for the data phase of the CAN FD frame has to be
1418 at least the bitrate which was configured for the arbitration phase. This
1421 dsample-point, dsjw or dtq and similar settings. When a data bitrate is set
1430 - ISO compliant: The ISO 11898-1:2015 CAN FD implementation (default)
1431 - non-ISO compliant: The CAN FD implementation following the 2012 whitepaper
1436 2. non-ISO compliant (fixed, like the M_CAN IP core v3.0.1 in m_can.c)
1437 3. ISO/non-ISO CAN FD controllers (switchable, like the PEAK PCAN-USB FD)
1439 The current ISO/non-ISO mode is announced by the CAN controller driver via
1440 netlink and displayed by the 'ip' tool (controller option FD-NON-ISO).
1441 The ISO/non-ISO-mode can be altered by setting 'fd-non-iso {on|off}' for
1446 $ ip link set can0 up type can bitrate 500000 sample-point 0.75 \
1447 dbitrate 4000000 dsample-point 0.8 fd on
1448 $ ip -details link show can0
1452 can <FD> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
1453 bitrate 500000 sample-point 0.750
1454 tq 50 prop-seg 14 phase-seg1 15 phase-seg2 10 sjw 1
1456 brp-inc 1
1457 dbitrate 4000000 dsample-point 0.800
1458 dtq 12 dprop-seg 7 dphase-seg1 8 dphase-seg2 4 dsjw 1
1460 dbrp-inc 1
1463 Example when 'fd-non-iso on' is added on this switchable CAN FD adapter::
1465 can <FD,FD-NON-ISO> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
1469 ----------------------
1473 (see :ref:`socketcan-resources`) there might be further drivers available, also for
1477 .. _socketcan-resources:
1489 - Oliver Hartkopp (PF_CAN core, filters, drivers, bcm, SJA1000 driver)
1490 - Urs Thuermann (PF_CAN core, kernel integration, socket interfaces, raw, vcan)
1491 - Jan Kizka (RT-SocketCAN core, Socket-API reconciliation)
1492 - Wolfgang Grandegger (RT-SocketCAN core & drivers, Raw Socket-API reviews, CAN device driver inter…
1493 - Robert Schwebel (design reviews, PTXdist integration)
1494 - Marc Kleine-Budde (design reviews, Kernel 2.6 cleanups, drivers)
1495 - Benedikt Spranger (reviews)
1496 - Thomas Gleixner (LKML reviews, coding style, posting hints)
1497 - Andrey Volkov (kernel subtree structure, ioctls, MSCAN driver)
1498 - Matthias Brukner (first SJA1000 CAN netdevice implementation Q2/2003)
1499 - Klaus Hitschler (PEAK driver integration)
1500 - Uwe Koppe (CAN netdevices with PF_PACKET approach)
1501 - Michael Schulze (driver layer loopback requirement, RT CAN drivers review)
1502 - Pavel Pisa (Bit-timing calculation)
1503 - Sascha Hauer (SJA1000 platform driver)
1504 - Sebastian Haas (SJA1000 EMS PCI driver)
1505 - Markus Plessing (SJA1000 EMS PCI driver)
1506 - Per Dalen (SJA1000 Kvaser PCI driver)
1507 - Sam Ravnborg (reviews, coding style, kbuild help)