can: Add documentation for virtual CAN driver usage
This patch adds a usage documentation for the virtual CAN driver (vcan). Signed-off-by: Oliver Hartkopp <oliver@hartkopp.net> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -35,8 +35,9 @@ This file contains
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6.1 general settings
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6.1 general settings
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6.2 local loopback of sent frames
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6.2 local loopback of sent frames
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6.3 CAN controller hardware filters
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6.3 CAN controller hardware filters
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6.4 currently supported CAN hardware
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6.4 The virtual CAN driver (vcan)
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6.5 todo
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6.5 currently supported CAN hardware
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6.6 todo
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7 Credits
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7 Credits
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@ -584,7 +585,42 @@ solution for a couple of reasons:
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@133MHz with four SJA1000 CAN controllers from 2002 under heavy bus
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@133MHz with four SJA1000 CAN controllers from 2002 under heavy bus
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load without any problems ...
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load without any problems ...
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6.4 currently supported CAN hardware (September 2007)
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6.4 The virtual CAN driver (vcan)
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Similar to the network loopback devices, vcan offers a virtual local
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CAN interface. A full qualified address on CAN consists of
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- a unique CAN Identifier (CAN ID)
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- the CAN bus this CAN ID is transmitted on (e.g. can0)
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so in common use cases more than one virtual CAN interface is needed.
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The virtual CAN interfaces allow the transmission and reception of CAN
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frames without real CAN controller hardware. Virtual CAN network
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devices are usually named 'vcanX', like vcan0 vcan1 vcan2 ...
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When compiled as a module the virtual CAN driver module is called vcan.ko
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Since Linux Kernel version 2.6.24 the vcan driver supports the Kernel
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netlink interface to create vcan network devices. The creation and
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removal of vcan network devices can be managed with the ip(8) tool:
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- Create a virtual CAN network interface:
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ip link add type vcan
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- Create a virtual CAN network interface with a specific name 'vcan42':
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ip link add dev vcan42 type vcan
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- Remove a (virtual CAN) network interface 'vcan42':
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ip link del vcan42
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The tool 'vcan' from the SocketCAN SVN repository on BerliOS is obsolete.
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Virtual CAN network device creation in older Kernels:
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In Linux Kernel versions < 2.6.24 the vcan driver creates 4 vcan
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netdevices at module load time by default. This value can be changed
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with the module parameter 'numdev'. E.g. 'modprobe vcan numdev=8'
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6.5 currently supported CAN hardware
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On the project website http://developer.berlios.de/projects/socketcan
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On the project website http://developer.berlios.de/projects/socketcan
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there are different drivers available:
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there are different drivers available:
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@ -603,7 +639,7 @@ solution for a couple of reasons:
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Please check the Mailing Lists on the berlios OSS project website.
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Please check the Mailing Lists on the berlios OSS project website.
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6.5 todo (September 2007)
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6.6 todo
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The configuration interface for CAN network drivers is still an open
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The configuration interface for CAN network drivers is still an open
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issue that has not been finalized in the socketcan project. Also the
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issue that has not been finalized in the socketcan project. Also the
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