[Xenomai-help] Comedi over RTDM

[Xenomai-help] Comedi over RTDM

[nourry]

Hi all,

Alex told me that a Comedi port to RTDM exists.

What does this mean ? If i'm able to write a driver for Comedi, this one will
work with RTDM and thus with Xenomai ?

I can't see where is the link between both and can't neither find information on
that port.

does anybody have recent examples of driver working with Comedi/RTDM ?

many thanks,
Antoine

Re: [Xenomai-help] Comedi over RTDM

[Alexis Berlemont]

Hi,

> Alex told me that a Comedi port to RTDM exists.
>
> What does this mean ? If i'm able to write a driver for Comedi, this one
> will work with RTDM and thus with Xenomai ?
>
> I can't see where is the link between both and can't neither find
> information on that port.
>
> does anybody have recent examples of driver working with Comedi/RTDM ?
>

Originally, Comedi is a framework for acquisition drivers which can be used in 
a common Linux system and in some specific real-time context.

This project was initiated by David Schleed. Have a look at the Comedi 
website: www.comedi.org. Many documents detail the main ideas.

A little while after the development of RTDM by Jan Kiszka, I started to work 
on a literal porting of Comedi over RTDM during my free time. I faced no 
specific issues for the porting of the kernel side of Comedi. But, on the 
user side, as far as I remember, things were different. I had some 
difficulties to ensure the real-time context considering the use of common 
Linux API in the Comedi library (malloc).

So I sent a mail to the Comedi mailing-list to tell that I was interested in 
writing a reviewed Comedi port for RTDM (here is a link 
http://osdir.com/ml/comedi/2006-04/msg00017.html).

This task took a long time as I can only work on it during my spare-time 
(roughly one or two hours per day; my job is not related with Comedi). 

Eventually (at last), the "comedi-rtdm-dev" branch reached a stable state (a 
few weeks ago). The "comedi-rtdm-dev" consists of a kernel framework and a 
user-space library. Right now, the critical issue is the recovery of the 
original Comedi drivers. And, more critically, the integration of new drivers 
for new devices.

On that last point, I hope some external contributions will help the 
Comedi4RTDM drivers set to grow as I have no acquisition cards and no way to 
get some.

By the way, if anyone is interested in Comedi, feel free to help me and / or 
criticize / improve the code I wrote.

Best regards.

Alexis.

Re: [Xenomai-help] Comedi over RTDM

[Leopold Palomo Avellaneda]

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A Dijous 26 Juny 2008, Alexis Berlemont va escriure:
> Hi,
>
> > Alex told me that a Comedi port to RTDM exists.
> >
> > What does this mean ? If i'm able to write a driver for Comedi, this one
> > will work with RTDM and thus with Xenomai ?
> >
> > I can't see where is the link between both and can't neither find
> > information on that port.
> >
> > does anybody have recent examples of driver working with Comedi/RTDM ?
>
> Originally, Comedi is a framework for acquisition drivers which can be used
> in a common Linux system and in some specific real-time context.
>
> This project was initiated by David Schleed. Have a look at the Comedi
> website: www.comedi.org. Many documents detail the main ideas.
>
> A little while after the development of RTDM by Jan Kiszka, I started to
> work on a literal porting of Comedi over RTDM during my free time. I faced
> no specific issues for the porting of the kernel side of Comedi. But, on
> the user side, as far as I remember, things were different. I had some
> difficulties to ensure the real-time context considering the use of common
> Linux API in the Comedi library (malloc).
>
> So I sent a mail to the Comedi mailing-list to tell that I was interested
> in writing a reviewed Comedi port for RTDM (here is a link
> http://osdir.com/ml/comedi/2006-04/msg00017.html).
>
> This task took a long time as I can only work on it during my spare-time
> (roughly one or two hours per day; my job is not related with Comedi).
>
> Eventually (at last), the "comedi-rtdm-dev" branch reached a stable state
> (a few weeks ago). The "comedi-rtdm-dev" consists of a kernel framework and
> a user-space library. Right now, the critical issue is the recovery of the
> original Comedi drivers. And, more critically, the integration of new
> drivers for new devices.
>
> On that last point, I hope some external contributions will help the
> Comedi4RTDM drivers set to grow as I have no acquisition cards and no way
> to get some.
>
> By the way, if anyone is interested in Comedi, feel free to help me and /
> or criticize / improve the code I wrote.

Alexis,

I would like to help, specially with the jr3 sensor, but I have to admit that 
you need a level of kernel programing, or comedi or xenomai that I don't 
have, and it's very frustrate.

I don't understand "exactly" what is comedi-rtdm-dev. You are saying that it's 
a:
> The "comedi-rtdm-dev" consists of a kernel framework 

and this is a?

some kernel modules? 
some templates to generate a kernel module with xenomai?
some code to develop a bridge betwend xenomai and the comedi driver?
a wrapper to encapsulate the comedi driver into a xenomai kernel module?
...
> and 
> a user-space library.

some .h and a .so that let you work with  the modules with xenomai and comedi?

Regards,

Leo


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Re: [Xenomai-help] Comedi over RTDM

[Alexis Berlemont]

Hi,

> I don't understand "exactly" what is comedi-rtdm-dev. 

Sorry I should have named it Comedi over RTDM or 
Comedi4RTDM, "comedi-rtdm-dev" is just the name of the branch containing the 
Comedi code (kernel core framework + kernel test drivers + user library + 
user binary examples) in the Xenomai subversion repository.

> You are saying that 
> it's
>
> a:
> > The "comedi-rtdm-dev" consists of a kernel framework
>
> and this is a?
>
> some kernel modules?
> some templates to generate a kernel module with xenomai?
> some code to develop a bridge betwend xenomai and the comedi driver?
> a wrapper to encapsulate the comedi driver into a xenomai kernel module?
> ...
>
> > and
> > a user-space library.
>
> some .h and a .so that let you work with  the modules with xenomai and
> comedi?

Best regards.

Alexis.

Re: [Xenomai-help] Comedi over RTDM

[Klaas Gadeyne]

Hi Alexis,

On Thu, 26 Jun 2008, Alexis Berlemont wrote:
[...]
> Eventually (at last), the "comedi-rtdm-dev" branch reached a stable state (a
> few weeks ago). The "comedi-rtdm-dev" consists of a kernel framework and a
> user-space library. Right now, the critical issue is the recovery of the
> original Comedi drivers. And, more critically, the integration of new drivers
> for new devices.

Is your port xenomai-version independent yet?  Or maybe better, which version do you use to test things?

> On that last point, I hope some external contributions will help the
> Comedi4RTDM drivers set to grow as I have no acquisition cards and no way to
> get some.

What effort/steps does it take to port an existing driver into comedi-rtdm-dev?

regards,

Klaas

Re: [Xenomai-help] Comedi over RTDM

[Philippe Gerum]

Klaas Gadeyne wrote:
> Hi Alexis,
> 
> On Thu, 26 Jun 2008, Alexis Berlemont wrote:
> [...]
>> Eventually (at last), the "comedi-rtdm-dev" branch reached a stable state (a
>> few weeks ago). The "comedi-rtdm-dev" consists of a kernel framework and a
>> user-space library. Right now, the critical issue is the recovery of the
>> original Comedi drivers. And, more critically, the integration of new drivers
>> for new devices.
> 
> Is your port xenomai-version independent yet?  Or maybe better, which version do you use to test things?
> 

Sidenote: there is a plan to have Alex's work merged into the upcoming 2.5. This
will allow us to complete the jigsaw puzzle on the Xenomai side, paving the way
to a comprehensive RTDM-based real-time device driver suite.

-- 
Philippe.

Re: [Xenomai-help] Comedi over RTDM

[Alexis Berlemont]

Hi,

>
> Is your port xenomai-version independent yet?  Or maybe better, which
> version do you use to test things?

I work with the Xenomai trunk. I already checked with Xenomai 2.4. It should 
work with Xenomai 2.2 / 2.3 but I have not checked recently.

As Philippe told you, this compatibility point must not be an issue thanks to 
the integration of Comedi into the next Xenomai releases.

> > On that last point, I hope some external contributions will help the
> > Comedi4RTDM drivers set to grow as I have no acquisition cards and no way
> > to get some.
>
> What effort/steps does it take to port an existing driver into
> comedi-rtdm-dev?

I have to write a document to explain the little things to update. No deep 
change must be performed as the main concepts (subdevice, channel, range, 
instruction, command, etc.) are the same. However, some functions 
declarations evolved for (I hope) more simplicity. For example, I tried to 
provide a generic API to transfer data thanks to the asynchronous buffer (via 
command) with and without DMA (comedi_buf_put(), comedi_buf_get(), etc.).

To give you an idea: adapting the original Comedi driver "jr3_pci" took me 2-3 
evenings (it was not longer than 4-5 hours if I remember well). I was not 
familiar with this driver, I discovered it during the port.

More documentation should be available, I am working on it.

Best regards.

Alexis.