Re: [RFC] A CAN Bus (SocketCAN-like) networking stack for FreeBSD

Hi,
Some progress in implementation?


Dne 2025-10-29 06:08, Adrian Chadd napsal:
> hi! did anyone get back to you about this?
> 
> Yes I think CAN support would benefit the community! Please send over
> some diffs and we can start reviewing!
> 
> -adrian
> 
> On Thu, 18 Sept 2025 at 09:58, Jérémie JOURDIN
> <[email protected]> wrote:
> 
>> Hello,
>> 
>> This is an update to my initial proposal regarding a CAN Bus stack
>> for FreeBSD. I'm happy to report that we now have a working
>> proof-of-concept implementation.
>> 
>> For context, this project—tentatively named "NetCAN"—provides
>> kernel-level support for the Controller Area Network protocol,
>> modeled after the widely adopted Linux SocketCAN framework. It
>> introduces the PF_CAN protocol family, allowing userland
>> applications to interact with CAN bus hardware through a standard
>> socket API.
>> 
>> The stack is designed to be modular, with a clear separation between
>> the protocol implementation, the generic network interface layer
>> (can_if), and hardware-specific device drivers.
>> 
>> So far, the project is composed of:
>> 
>> Kernel Modules
>> 
>> * can.ko: Core module registering the PF_CAN protocol family and
>> the CAN netisr.
>> * can_raw.ko: CAN_RAW protocol implementation for SOCK_RAW sockets.
>> * vcan.ko: Virtual CAN loopback driver (vcanX), which is CAN FD
>> capable.
>> 
>> User-space Tools
>> 
>> * canconfig: Utility for configuring CAN interfaces (bitrate,
>> mode, etc.).
>> * canutils (candump, cansend): A port of the essential Linux
>> can-utils.
>> 
>> -------------------------
>> 
>> Stack Architecture Overview
>> 
>> The architecture is designed to align with standard FreeBSD
>> networking practices.
>> 
>> can.c (Core Domain): Registers the PF_CAN/AF_CAN domain.
>> 
>> can_raw.c (Raw Socket): Manages the CAN_RAW protocol, socket
>> lifecycle, send/write operations, setsockopt, and packet delivery
>> from the netisr to sockets via software filters.
>> 
>> can_if.c (Generic Interface Layer): Provides the ifnet abstraction
>> (canX) for all hardware drivers. It handles the if_transmit entry
>> point, software loopback, and exposes service routines for drivers
>> to report bus state and errors.
>> 
>> struct can_softc (Driver Contract): The contract a hardware driver
>> must fulfill, providing function pointers for hardware-specific
>> operations (transmit, set bitrate, etc.).
>> 
>> -------------------------
>> 
>> We are already planning to use it in our own FreeBSD-based products,
>> which ensures we have a strong commitment to its long-term
>> maintenance.
>> Our goal would be to contribute this stack to the FreeBSD base
>> system.
>> 
>> Before preparing a formal submission, I am seeking feedback from the
>> community, specifically on:
>> 
>> * The overall architecture and API design.
>> * Real-world use cases or specific hardware (CAN adapters) that you
>> believe are critical to support.
>> * Any obvious design patterns that feel more aligned with Linux
>> than FreeBSD and could be improved.
>> 
>> Any and all feedback is welcome.
>> 
>> Thank you,
>> 
>> Jérémie
>> 
>> From: Jérémie JOURDIN <[email protected]>
>> Date: Monday, 23 June 2025 at 08:57
>> To: Tomek CEDRO <[email protected]>
>> Cc: [email protected] <[email protected]>
>> Subject: Re: FreeBSD-native CAN Stack and AF_CAN Protocol Family
>> 
>> Theoretically, yes, the CAN stack is intended to be
>> hardware-independent.
>> 
>> I suppose there will also be drivers to create or modify, but that
>> shouldn’t be the most complicated part.
>> 
>> De : Tomek CEDRO <[email protected]>
>> Date : vendredi, 20 juin 2025 à 20:29
>> À : Jérémie JOURDIN <[email protected]>
>> Cc : [email protected] <[email protected]>
>> Objet : Re: FreeBSD-native CAN Stack and AF_CAN Protocol Family
>> 
>> CAUTION: External Sender. This email originated from outside of
>> ADVENS. Do not click on links or open attachments from senders you
>> do not trust.
>> 
>> On Fri, Jun 20, 2025, 14:52 Jérémie JOURDIN
>> <[email protected]> wrote:
>> 
>>> Hello all,
>>> 
>>> I am working on a system (15-current) that requires interaction
>>> with a CAN network.
>>> 
>>> So far, I have developped a driver for my controller, able to send
>>> and receive CAN frames to and from connected devices.
>>> 
>>> I’d like to implement a FreeBSD-native CAN network stack that is
>>> API-compatible with Linux’s Netlink CAN (netcan).
>>> 
>>> This would allow us to recompile and use existing Linux userland
>>> tools with minimal changes.
>>> 
>>> If you believe this development could benefit the community, I
>>> would be happy to submit a set of patches (driver + netcan
>>> support).
>>> 
>>> We’re considering defining a new Protocol Family, AF_CAN, for
>>> this purpose.
>>> 
>>> Would it be acceptable to use the first available « AF_VENDORXX
>>> » from sys/socket.h ?
>>> 
>>> I would appreciate your thoughts, advice, and any recommendations
>>> you may have on this matter.
>>> 
>>> -- Jérémie
>> 
>> Hello Jeremie, sounds great! :-) Would that work with simple
>> USB-UART-CAN adapters? :-)
>> 
>> --
>> CeDeROM, SQ7MHZ, http://www.tomek.cedro.info [1]
> 
> 
> Links:
> ------
> [1] http://www.tomek.cedro.info/