From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Hartkopp Subject: [PATCH] can: add documentation about CAN FD controller specific configuration Date: Thu, 17 Sep 2015 21:58:46 +0200 Message-ID: <1442519926-4506-1-git-send-email-socketcan@hartkopp.net> Return-path: Received: from mo4-p00-ob.smtp.rzone.de ([81.169.146.160]:22589 "EHLO mo4-p00-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750974AbbIQT7D (ORCPT ); Thu, 17 Sep 2015 15:59:03 -0400 Sender: linux-can-owner@vger.kernel.org List-ID: To: linux-can@vger.kernel.org Cc: Oliver Hartkopp Signed-off-by: Oliver Hartkopp --- Documentation/networking/can.txt | 75 +++++++++++++++++++++++++++++----------- 1 file changed, 55 insertions(+), 20 deletions(-) diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt index fd1a1aa..56bad15 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 +1187,33 @@ 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. 6.7 Supported CAN hardware -- 2.1.4