docs/can: convert to restructuredText

Buglink: https://gitlab.com/qemu-project/qemu/-/issues/527
Signed-off-by: Lucas Ramage <lucas.ramage@infinite-omicron.com>
Message-id: 20220105205628.5491-1-oxr463@gmx.us
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: Move to docs/system/devices/ rather than top-level;
 fix a pre-existing typo in passing]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 188 insertions, 0 deletions

diff --git a/docs/system/devices/can.rst b/docs/system/devices/can.rst
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+CAN Bus Emulation Support
+=========================
+The CAN bus emulation provides mechanism to connect multiple
+emulated CAN controller chips together by one or multiple CAN busses
+(the controller device "canbus"  parameter). The individual busses
+can be connected to host system CAN API (at this time only Linux
+SocketCAN is supported).
+
+The concept of busses is generic and different CAN controllers
+can be implemented.
+
+The initial submission implemented SJA1000 controller which
+is common and well supported by by drivers for the most operating
+systems.
+
+The PCI addon card hardware has been selected as the first CAN
+interface to implement because such device can be easily connected
+to systems with different CPU architectures (x86, PowerPC, Arm, etc.).
+
+In 2020, CTU CAN FD controller model has been added as part
+of the bachelor thesis of Jan Charvat. This controller is complete
+open-source/design/hardware solution. The core designer
+of the project is Ondrej Ille, the financial support has been
+provided by CTU, and more companies including Volkswagen subsidiaries.
+
+The project has been initially started in frame of RTEMS GSoC 2013
+slot by Jin Yang under our mentoring  The initial idea was to provide generic
+CAN subsystem for RTEMS. But lack of common environment for code and RTEMS
+testing lead to goal change to provide environment which provides complete
+emulated environment for testing and RTEMS GSoC slot has been donated
+to work on CAN hardware emulation on QEMU.
+
+Examples how to use CAN emulation for SJA1000 based boards
+----------------------------------------------------------
+When QEMU with CAN PCI support is compiled then one of the next
+CAN boards can be selected
+
+(1) CAN bus Kvaser PCI CAN-S (single SJA1000 channel) board. QEMU startup options::
+
+    -object can-bus,id=canbus0
+    -device kvaser_pci,canbus=canbus0
+
+Add "can-host-socketcan" object to connect device to host system CAN bus::
+
+    -object can-host-socketcan,id=canhost0,if=can0,canbus=canbus0
+
+(2) CAN bus PCM-3680I PCI (dual SJA1000 channel) emulation::
+
+    -object can-bus,id=canbus0
+    -device pcm3680_pci,canbus0=canbus0,canbus1=canbus0
+
+Another example::
+
+    -object can-bus,id=canbus0
+    -object can-bus,id=canbus1
+    -device pcm3680_pci,canbus0=canbus0,canbus1=canbus1
+
+(3) CAN bus MIOe-3680 PCI (dual SJA1000 channel) emulation::
+
+    -device mioe3680_pci,canbus0=canbus0
+
+The ''kvaser_pci'' board/device model is compatible with and has been tested with
+the ''kvaser_pci'' driver included in mainline Linux kernel.
+The tested setup was Linux 4.9 kernel on the host and guest side.
+
+Example for qemu-system-x86_64::
+
+    qemu-system-x86_64 -accel kvm -kernel /boot/vmlinuz-4.9.0-4-amd64 \
+      -initrd ramdisk.cpio \
+      -virtfs local,path=shareddir,security_model=none,mount_tag=shareddir \
+      -object can-bus,id=canbus0 \
+      -object can-host-socketcan,id=canhost0,if=can0,canbus=canbus0 \
+      -device kvaser_pci,canbus=canbus0 \
+      -nographic -append "console=ttyS0"
+
+Example for qemu-system-arm::
+
+    qemu-system-arm -cpu arm1176 -m 256 -M versatilepb \
+      -kernel kernel-qemu-arm1176-versatilepb \
+      -hda rpi-wheezy-overlay \
+      -append "console=ttyAMA0 root=/dev/sda2 ro init=/sbin/init-overlay" \
+      -nographic \
+      -virtfs local,path=shareddir,security_model=none,mount_tag=shareddir \
+      -object can-bus,id=canbus0 \
+      -object can-host-socketcan,id=canhost0,if=can0,canbus=canbus0 \
+      -device kvaser_pci,canbus=canbus0,host=can0 \
+
+The CAN interface of the host system has to be configured for proper
+bitrate and set up. Configuration is not propagated from emulated
+devices through bus to the physical host device. Example configuration
+for 1 Mbit/s::
+
+  ip link set can0 type can bitrate 1000000
+  ip link set can0 up
+
+Virtual (host local only) can interface can be used on the host
+side instead of physical interface::
+
+  ip link add dev can0 type vcan
+
+The CAN interface on the host side can be used to analyze CAN
+traffic with "candump" command which is included in "can-utils"::
+
+  candump can0
+
+CTU CAN FD support examples
+---------------------------
+This open-source core provides CAN FD support. CAN FD drames are
+delivered even to the host systems when SocketCAN interface is found
+CAN FD capable.
+
+The PCIe board emulation is provided for now (the device identifier is
+ctucan_pci). The default build defines two CTU CAN FD cores
+on the board.
+
+Example how to connect the canbus0-bus (virtual wire) to the host
+Linux system (SocketCAN used) and to both CTU CAN FD cores emulated
+on the corresponding PCI card expects that host system CAN bus
+is setup according to the previous SJA1000 section::
+
+  qemu-system-x86_64 -enable-kvm -kernel /boot/vmlinuz-4.19.52+ \
+      -initrd ramdisk.cpio \
+      -virtfs local,path=shareddir,security_model=none,mount_tag=shareddir \
+      -vga cirrus \
+      -append "console=ttyS0" \
+      -object can-bus,id=canbus0-bus \
+      -object can-host-socketcan,if=can0,canbus=canbus0-bus,id=canbus0-socketcan \
+      -device ctucan_pci,canbus0=canbus0-bus,canbus1=canbus0-bus \
+      -nographic
+
+Setup of CTU CAN FD controller in a guest Linux system::
+
+  insmod ctucanfd.ko || modprobe ctucanfd
+  insmod ctucanfd_pci.ko || modprobe ctucanfd_pci
+
+  for ifc in /sys/class/net/can* ; do
+    if [ -e  $ifc/device/vendor ] ; then
+      if ! grep -q 0x1760 $ifc/device/vendor ; then
+        continue;
+      fi
+    else
+      continue;
+    fi
+    if [ -e  $ifc/device/device ] ; then
+       if ! grep -q 0xff00 $ifc/device/device ; then
+         continue;
+       fi
+    else
+      continue;
+    fi
+    ifc=$(basename $ifc)
+    /bin/ip link set $ifc type can bitrate 1000000 dbitrate 10000000 fd on
+    /bin/ip link set $ifc up
+  done
+
+The test can run for example::
+
+  candump can1
+
+in the guest system and next commands in the host system for basic CAN::
+
+  cangen can0
+
+for CAN FD without bitrate switch::
+
+  cangen can0 -f
+
+and with bitrate switch::
+
+  cangen can0 -b
+
+The test can be run viceversa, generate messages in the guest system and capture them
+in the host one and much more combinations.
+
+Links to other resources
+------------------------
+
+ (1) `CAN related projects at Czech Technical University, Faculty of Electrical Engineering <http://canbus.pages.fel.cvut.cz>`_
+ (2) `Repository with development can-pci branch at Czech Technical University <https://gitlab.fel.cvut.cz/canbus/qemu-canbus>`_
+ (3) `RTEMS page describing project <https://devel.rtems.org/wiki/Developer/Simulators/QEMU/CANEmulation>`_
+ (4) `RTLWS 2015 article about the project and its use with CANopen emulation <http://cmp.felk.cvut.cz/~pisa/can/doc/rtlws-17-pisa-qemu-can.pdf>`_
+ (5) `GNU/Linux, CAN and CANopen in Real-time Control Applications Slides from LinuxDays 2017 (include updated RTLWS 2015 content) <https://www.linuxdays.cz/2017/video/Pavel_Pisa-CAN_canopen.pdf>`_
+ (6) `Linux SocketCAN utilities <https://github.com/linux-can/can-utils>`_
+ (7) `CTU CAN FD project including core VHDL design, Linux driver, test utilities etc. <https://gitlab.fel.cvut.cz/canbus/ctucanfd_ip_core>`_
+ (8) `CTU CAN FD Core Datasheet Documentation <http://canbus.pages.fel.cvut.cz/ctucanfd_ip_core/Progdokum.pdf>`_
+ (9) `CTU CAN FD Core System Architecture Documentation <http://canbus.pages.fel.cvut.cz/ctucanfd_ip_core/ctu_can_fd_architecture.pdf>`_
+ (10) `CTU CAN FD Driver Documentation <http://canbus.pages.fel.cvut.cz/ctucanfd_ip_core/driver_doc/ctucanfd-driver.html>`_
+ (11) `Integration with PCIe interfacing for Intel/Altera Cyclone IV based board <https://gitlab.fel.cvut.cz/canbus/pcie-ctu_can_fd>`_