diff options
| -rw-r--r-- | Documentation/networking/can.txt | 97 |
1 files changed, 77 insertions, 20 deletions
diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt index fd1a1aad49a9..4636b94518da 100644 --- a/Documentation/networking/can.txt +++ b/Documentation/networking/can.txt @@ -1018,25 +1018,34 @@ solution for a couple of reasons: $ ip link set can0 type can help Usage: ip link set DEVICE type can - [ bitrate BITRATE [ sample-point SAMPLE-POINT] ] | - [ tq TQ prop-seg PROP_SEG phase-seg1 PHASE-SEG1 - phase-seg2 PHASE-SEG2 [ sjw SJW ] ] - - [ loopback { on | off } ] - [ listen-only { on | off } ] - [ triple-sampling { on | off } ] - - [ restart-ms TIME-MS ] - [ restart ] - - Where: BITRATE := { 1..1000000 } - SAMPLE-POINT := { 0.000..0.999 } - TQ := { NUMBER } - PROP-SEG := { 1..8 } - PHASE-SEG1 := { 1..8 } - PHASE-SEG2 := { 1..8 } - SJW := { 1..4 } - RESTART-MS := { 0 | NUMBER } + [ bitrate BITRATE [ sample-point SAMPLE-POINT] ] | + [ tq TQ prop-seg PROP_SEG phase-seg1 PHASE-SEG1 + phase-seg2 PHASE-SEG2 [ sjw SJW ] ] + + [ dbitrate BITRATE [ dsample-point SAMPLE-POINT] ] | + [ dtq TQ dprop-seg PROP_SEG dphase-seg1 PHASE-SEG1 + dphase-seg2 PHASE-SEG2 [ dsjw SJW ] ] + + [ loopback { on | off } ] + [ listen-only { on | off } ] + [ triple-sampling { on | off } ] + [ one-shot { on | off } ] + [ berr-reporting { on | off } ] + [ fd { on | off } ] + [ fd-non-iso { on | off } ] + [ presume-ack { on | off } ] + + [ restart-ms TIME-MS ] + [ restart ] + + Where: BITRATE := { 1..1000000 } + SAMPLE-POINT := { 0.000..0.999 } + TQ := { NUMBER } + PROP-SEG := { 1..8 } + PHASE-SEG1 := { 1..8 } + PHASE-SEG2 := { 1..8 } + SJW := { 1..4 } + RESTART-MS := { 0 | NUMBER } - Display CAN device details and statistics: @@ -1178,7 +1187,55 @@ solution for a couple of reasons: The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall. N.B. CAN FD capable devices can also handle and send legacy CAN frames. - FIXME: Add details about the CAN FD controller configuration when available. + When configuring CAN FD capable CAN controllers an additional 'data' bitrate + has to be set. This bitrate for the data phase of the CAN FD frame has to be + at least the bitrate which was configured for the arbitration phase. This + second bitrate is specified analogue to the first bitrate but the bitrate + setting keywords for the 'data' bitrate start with 'd' e.g. dbitrate, + dsample-point, dsjw or dtq and similar settings. When a data bitrate is set + within the configuration process the controller option "fd on" can be + specified to enable the CAN FD mode in the CAN controller. This controller + option also switches the device MTU to 72 (CANFD_MTU). + + The first CAN FD specification presented as whitepaper at the International + CAN Conference 2012 needed to be improved for data integrity reasons. + Therefore two CAN FD implementations have to be distinguished today: + + - ISO compliant: The ISO 11898-1:2015 CAN FD implementation (default) + - non-ISO compliant: The CAN FD implementation following the 2012 whitepaper + + Finally there are three types of CAN FD controllers: + + 1. ISO compliant (fixed) + 2. non-ISO compliant (fixed, like the M_CAN IP core v3.0.1 in m_can.c) + 3. ISO/non-ISO CAN FD controllers (switchable, like the PEAK PCAN-USB FD) + + The current ISO/non-ISO mode is announced by the CAN controller driver via + netlink and displayed by the 'ip' tool (controller option FD-NON-ISO). + The ISO/non-ISO-mode can be altered by setting 'fd-non-iso {on|off}' for + switchable CAN FD controllers only. + + Example configuring 500 kbit/s arbitration bitrate and 4 Mbit/s data bitrate: + + $ ip link set can0 up type can bitrate 500000 sample-point 0.75 \ + dbitrate 4000000 dsample-point 0.8 fd on + $ ip -details link show can0 + 5: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 72 qdisc pfifo_fast state UNKNOWN \ + mode DEFAULT group default qlen 10 + link/can promiscuity 0 + can <FD> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0 + bitrate 500000 sample-point 0.750 + tq 50 prop-seg 14 phase-seg1 15 phase-seg2 10 sjw 1 + pcan_usb_pro_fd: tseg1 1..64 tseg2 1..16 sjw 1..16 brp 1..1024 \ + brp-inc 1 + dbitrate 4000000 dsample-point 0.800 + dtq 12 dprop-seg 7 dphase-seg1 8 dphase-seg2 4 dsjw 1 + pcan_usb_pro_fd: dtseg1 1..16 dtseg2 1..8 dsjw 1..4 dbrp 1..1024 \ + dbrp-inc 1 + clock 80000000 + + Example when 'fd-non-iso on' is added on this switchable CAN FD adapter: + can <FD,FD-NON-ISO> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0 6.7 Supported CAN hardware |