Re: Status of CAN API?
Hello Philip, Gedare and others interested in RTEMS CAN/CAN FD API, On Tuesday 22 of August 2023 14:11:22 Philip Kirkpatrick wrote: > Thank you for your input on this. I'm still digesting LinCAN, but it looks > like a good way to go. On our end, we will likely have some resources to > throw at this in a few weeks. LinCAN has been designed as full featured, vendor neutral character driver API based CAN stack for Linux and RTOS RT Linux kernel with ability to be accessed from Linux user-land and RT Linux modules in the second case. https://ortcan.sourceforge.net/lincan/ But SocketCAN is the choice for Linux kernel CAN support today. It has nicer API but has it problems on real-time side etc... Even from our experience with NuttX CAN drivers development I tend to stay with character driver API for RTEMS in the current iteration... Potability of LinCAN to RTEMS and even bare metal HW without scheduler has been taken in mind. There is a branch can-usb1 which used slightly modified SJA1000 LinCAN chip driver together with LinCAN infrastructure to provide low level API (only FIFOs, no POSIX read/write call) in system less mode to implement USB to CAN converter on old NXP LPC21xx and SJA1000 or newer LPC17xx targets https://sourceforge.net/p/ortcan/lincan/ci/can-usb1/tree/embedded/app/usbcan/ We have implemented the companion Linux kernel LinCAN and SocketCAN drivers which allowed to use even USB converter in addition to ISA and PCI bus connected CAN controllers... > On Thu, Aug 17, 2023 at 4:26 PM Gedare Bloom wrote: > > Hi Phil, > > > > On Wed, Aug 9, 2023 at 6:38 AM Philip Kirkpatrick > > > > wrote: > > > Hello, > > > > > > Some people on our team here at Reflex are preparing to implement some > > > > CAN drivers. Specifically for TMS570 and for ZynqMP-RPU (side note my > > latest patch for that on Jun 29th is still sitting there unreviewed). I > > was wondering what the current status of the CAN API is. > > Feel free to ping the patch. At the moment, this email based system is > > all we have, and sometimes patches may not get a lot of attention > > especially if no one "owns" it -- such as new BSPs. > > > > > I saw in August of last year and API was added and then last month was > > > > reverted with this patch: > > > https://lists.rtems.org/pipermail/devel/2023-July/076013.html > > > The comment on the patch says the API isn't mature enough for release. > > > > What deficiencies need to be resolved in the API, is this being actively > > worked on, and should we design against this API or is there a different > > API we should target? We plan keeping CAN/CAN FD structure (discussed and agreed upon with Oliver Hartkopp) and keep barely the same read/write code as is in already included CAN solution. I consider deep redesign of the rest as a must. > > The implementation of that API was deficient. It did not support > > multiple read/write transactions, it had a custom-built ring buffer > > that was not fully vetted, and some other problems related to > > threads+priorities. I expect to have some time to look at how to > > provide better CAN support inside of RTEMS. This has been an ongoing > > discussion I've been having with Pavel Pisa and others for many years > > now (a decade?). The direction that I will prefer to go is to port > > LinCAN > > https://cmp.felk.cvut.cz/~pisa/can/doc/lincandoc-0.3.5.pdf > > > > Both Pavel and I are interested in seeing this come through. So far, > > we mostly do it on volunteer time or as side pieces of other work. > > Pavel's group has good experience with CAN and CAN FD, and with both > > TMS570 and the Zynq (non-MP) boards, with Linux, RTEMS, and NuttX. We > > would be open to collaborating, subject to whatever time or resource > > constraints everyone has :) Michal Lenc has been working on this topic > > as a thesis, "CAN FD Support for Space Grade Real-Time RTEMS > > Executive" Or initial panned target is our own CTU CAN FD IP Core https://canbus.pages.fel.cvut.cz/ which we can test on our MZ_APO Zynq 7k based kits and have emulation for it in QEMU mainline etc... There has been James Holley working on Zynq 7k XCAN support during his intern under Noviumdesigns company funding, if I remember well. But I am not sure if there has been some final version released to public. It has been based on actual RTEMS CAN FIFOs stub and they planned to somehow fix it but if it. If it is offered under RTEMS mainline compatible license then it can be updated to CAN API and FIFOS after rewrite and used for RTEMS XCAN support in the next step. By the way Zynq-MP and Versal have advantage that Xilinx included corresponding CAN FD controllers model int
Re: Status of CAN API?
Gedare, Thank you for your input on this. I'm still digesting LinCAN, but it looks like a good way to go. On our end, we will likely have some resources to throw at this in a few weeks. -Phil On Thu, Aug 17, 2023 at 4:26 PM Gedare Bloom wrote: > Hi Phil, > > On Wed, Aug 9, 2023 at 6:38 AM Philip Kirkpatrick > wrote: > > > > Hello, > > > > Some people on our team here at Reflex are preparing to implement some > CAN drivers. Specifically for TMS570 and for ZynqMP-RPU (side note my > latest patch for that on Jun 29th is still sitting there unreviewed). I > was wondering what the current status of the CAN API is. > Feel free to ping the patch. At the moment, this email based system is > all we have, and sometimes patches may not get a lot of attention > especially if no one "owns" it -- such as new BSPs. > > > I saw in August of last year and API was added and then last month was > reverted with this patch: > > https://lists.rtems.org/pipermail/devel/2023-July/076013.html > > The comment on the patch says the API isn't mature enough for release. > What deficiencies need to be resolved in the API, is this being actively > worked on, and should we design against this API or is there a different > API we should target? > > > The implementation of that API was deficient. It did not support > multiple read/write transactions, it had a custom-built ring buffer > that was not fully vetted, and some other problems related to > threads+priorities. I expect to have some time to look at how to > provide better CAN support inside of RTEMS. This has been an ongoing > discussion I've been having with Pavel Pisa and others for many years > now (a decade?). The direction that I will prefer to go is to port > LinCAN > https://cmp.felk.cvut.cz/~pisa/can/doc/lincandoc-0.3.5.pdf > > Both Pavel and I are interested in seeing this come through. So far, > we mostly do it on volunteer time or as side pieces of other work. > Pavel's group has good experience with CAN and CAN FD, and with both > TMS570 and the Zynq (non-MP) boards, with Linux, RTEMS, and NuttX. We > would be open to collaborating, subject to whatever time or resource > constraints everyone has :) Michal Lenc has been working on this topic > as a thesis, "CAN FD Support for Space Grade Real-Time RTEMS > Executive" > > Regarding LinCAN itself, there is one design challenge to port it, > which has to do with the use of internal FIFOs already in LinCAN code > base, or to use RTEMS/POSIX message queue style to interface the CAN > drivers and userspace. I actually see there are good reasons to > support both ways, and may explore exactly that. We have had quite > some discussions here on the topic: > * https://lists.rtems.org/pipermail/devel/2023-March/074537.html > * https://lists.rtems.org/pipermail/devel/2022-April/071235.html > * https://lists.rtems.org/pipermail/devel/2013-April/030761.html (for > historical good measure) > > Gedare > > > Thank you, > > Phil > > ___ > > devel mailing list > > devel@rtems.org > > http://lists.rtems.org/mailman/listinfo/devel > ___ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
Re: Status of CAN API?
Hi Phil, On Wed, Aug 9, 2023 at 6:38 AM Philip Kirkpatrick wrote: > > Hello, > > Some people on our team here at Reflex are preparing to implement some CAN > drivers. Specifically for TMS570 and for ZynqMP-RPU (side note my latest > patch for that on Jun 29th is still sitting there unreviewed). I was > wondering what the current status of the CAN API is. Feel free to ping the patch. At the moment, this email based system is all we have, and sometimes patches may not get a lot of attention especially if no one "owns" it -- such as new BSPs. > I saw in August of last year and API was added and then last month was > reverted with this patch: > https://lists.rtems.org/pipermail/devel/2023-July/076013.html > The comment on the patch says the API isn't mature enough for release. What > deficiencies need to be resolved in the API, is this being actively worked > on, and should we design against this API or is there a different API we > should target? > The implementation of that API was deficient. It did not support multiple read/write transactions, it had a custom-built ring buffer that was not fully vetted, and some other problems related to threads+priorities. I expect to have some time to look at how to provide better CAN support inside of RTEMS. This has been an ongoing discussion I've been having with Pavel Pisa and others for many years now (a decade?). The direction that I will prefer to go is to port LinCAN https://cmp.felk.cvut.cz/~pisa/can/doc/lincandoc-0.3.5.pdf Both Pavel and I are interested in seeing this come through. So far, we mostly do it on volunteer time or as side pieces of other work. Pavel's group has good experience with CAN and CAN FD, and with both TMS570 and the Zynq (non-MP) boards, with Linux, RTEMS, and NuttX. We would be open to collaborating, subject to whatever time or resource constraints everyone has :) Michal Lenc has been working on this topic as a thesis, "CAN FD Support for Space Grade Real-Time RTEMS Executive" Regarding LinCAN itself, there is one design challenge to port it, which has to do with the use of internal FIFOs already in LinCAN code base, or to use RTEMS/POSIX message queue style to interface the CAN drivers and userspace. I actually see there are good reasons to support both ways, and may explore exactly that. We have had quite some discussions here on the topic: * https://lists.rtems.org/pipermail/devel/2023-March/074537.html * https://lists.rtems.org/pipermail/devel/2022-April/071235.html * https://lists.rtems.org/pipermail/devel/2013-April/030761.html (for historical good measure) Gedare > Thank you, > Phil > ___ > devel mailing list > devel@rtems.org > http://lists.rtems.org/mailman/listinfo/devel ___ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
Status of CAN API?
Hello, Some people on our team here at Reflex are preparing to implement some CAN drivers. Specifically for TMS570 and for ZynqMP-RPU (side note my latest patch for that on Jun 29th is still sitting there unreviewed). I was wondering what the current status of the CAN API is. I saw in August of last year and API was added and then last month was reverted with this patch: https://lists.rtems.org/pipermail/devel/2023-July/076013.html The comment on the patch says the API isn't mature enough for release. What deficiencies need to be resolved in the API, is this being actively worked on, and should we design against this API or is there a different API we should target? Thank you, Phil ___ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
