From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Subject: Re: [RFC] K-Line protocol via SocketCAN Date: Fri, 20 May 2016 13:59:31 +0200 Message-ID: <573EFC23.2040906@denx.de> References: <573E491E.1000906@denx.de> <573EAE9D.20006@hartkopp.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-out.m-online.net ([212.18.0.9]:57383 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752075AbcETL7w (ORCPT ); Fri, 20 May 2016 07:59:52 -0400 In-Reply-To: <573EAE9D.20006@hartkopp.net> Sender: linux-can-owner@vger.kernel.org List-ID: To: Oliver Hartkopp , Mirza Krak Cc: "linux-can@vger.kernel.org" , Marc Kleine-Budde , Wolfgang Grandegger On 05/20/2016 08:28 AM, Oliver Hartkopp wrote: > Hi, Hi! > I removed Dave Miller from the discussion not to be tagged as SPAM :-) > That's not Daves focus as networking maintainer ... Heh, all right. > Here's an update about the LIN Status from Pavel Pisa: > > http://marc.info/?l=linux-can&m=146163127517268&w=2 I am aware of the sllin. There is also freediag , which implements kline protocol. > I remember a K-Line implementation for Linux where we had a MPC5200 UART > which we programmed with bit-banging of some control line to do the > 5bit/s opening pattern. > After that we went to 10400 bit/s and did some K-Line communication. > All this was done by a user space application on /dev/ttyS0. Yes, and this does make perfect sense until you start dealing with faster modes and need more precise timing. The K-Line is limited by 250kBaud/s bus speed. > What would be the advantages to put this into kernel space (or into the > CAN networking infrastructure)? I see two for putting this into the kernel: - At faster bus speeds, you can achieve more precise timing if this is in the kernel, both of the inter-byte delay and also for the timestamps. Having this in the kernel even allows usage of the realtime extensions if needed. - Dedicated hardware driver can plug into such K-Line infrastructure. Such hardware might be needed to support the faster modes to further increase the timing precision. And two for using socketcan/network interface: - The addressing support of the network stack can be mapped to K-Line bus addresses. - The rtnl can be used as an extensible interface for configuring the K-Line parameters. Cheers! > Regards, > Oliver > > > On 05/20/2016 08:04 AM, Mirza Krak wrote: >> 2016-05-20 1:15 GMT+02:00 Marek Vasut : >>> I will also need to add support for the LIN protocol and SENT protocol >>> further down the line. I will also likely revisit the Arinc at some >>> point afterward. So I would like to know how to deal with this protocol >>> mess. >> >> FYI, there has been a similar LIN project for quite a while [1]. You >> might have seen it earlier? >> >> [1]. http://rtime.felk.cvut.cz/gitweb/linux-lin.git >> -- Best regards, Marek Vasut