Making our own device work under Linux

Making our own device work under Linux

[Dmitriy Fitisov]

Hello everyone,
we have made our own device using STM32 chip and it works well under Windows using serial communication
through USB.
We used ST Micro supplied driver and firmware example.

  Now we have a task to make it work under Linux.
USB configuration is declared it as CDC modem, therefore Linux pickups cdc-acm driver and attach it to the device.
I tested it under Ununtu and it seems that once device is attached some program 
tests it using AT commands. I would guess it is ModemManager which is started in /etc/init/modemmanager.conf
I updated firmware on our device to process those commands, now I think I may simply remove ModemManager from startup and it would be fine.

But our final platform should be Raspberry.
It seems init here a little bit different, I do not see initctl program, man init differs and I'm getting different data on my device.
It sounds like terminal sequence, with lot of "0x20 0x08" bytes after start sequence.

So, I need to find out what program/daemon/service trying to communicate with cdc-acm.
Is there a simple easy way without recompiling kernel with debug info?

Thank you.
Dmitriy

Re: Making our own device work under Linux

[Greg KH]

On Fri, Nov 28, 2014 at 01:39:36PM -0500, Dmitriy Fitisov wrote:
> Hello everyone,
> we have made our own device using STM32 chip and it works well under Windows using serial communication
> through USB.
> We used ST Micro supplied driver and firmware example.
> 
>   Now we have a task to make it work under Linux.
> USB configuration is declared it as CDC modem, therefore Linux pickups cdc-acm driver and attach it to the device.
> I tested it under Ununtu and it seems that once device is attached some program 
> tests it using AT commands. I would guess it is ModemManager which is started in /etc/init/modemmanager.conf
> I updated firmware on our device to process those commands, now I think I may simply remove ModemManager from startup and it would be fine.
> 
> But our final platform should be Raspberry.
> It seems init here a little bit different, I do not see initctl program, man init differs and I'm getting different data on my device.
> It sounds like terminal sequence, with lot of "0x20 0x08" bytes after start sequence.
> 
> So, I need to find out what program/daemon/service trying to communicate with cdc-acm.
> Is there a simple easy way without recompiling kernel with debug info?

There are lots of different distros for the Raspberry Pi, I would
suggest asking on the mailing list of the distro you are using to try to
determine this, as the people there will be able to help you out the
best.

Good luck,

greg k-h

Re: Making our own device work under Linux

[Dmitriy Fitisov]

Thank you.
I registered on a forum, awaited activation.
Raspberry mailing list is virtually dead, producing a few kilobytes montly.
But anyway, it is pretty much Debian I would think.

On Nov 28, 2014, at 1:48 PM, Greg KH <gregkh@linuxfoundation.org> wrote:

> On Fri, Nov 28, 2014 at 01:39:36PM -0500, Dmitriy Fitisov wrote:
>> Hello everyone,
>> we have made our own device using STM32 chip and it works well under Windows using serial communication
>> through USB.
>> We used ST Micro supplied driver and firmware example.
>> 
>>  Now we have a task to make it work under Linux.
>> USB configuration is declared it as CDC modem, therefore Linux pickups cdc-acm driver and attach it to the device.
>> I tested it under Ununtu and it seems that once device is attached some program 
>> tests it using AT commands. I would guess it is ModemManager which is started in /etc/init/modemmanager.conf
>> I updated firmware on our device to process those commands, now I think I may simply remove ModemManager from startup and it would be fine.
>> 
>> But our final platform should be Raspberry.
>> It seems init here a little bit different, I do not see initctl program, man init differs and I'm getting different data on my device.
>> It sounds like terminal sequence, with lot of "0x20 0x08" bytes after start sequence.
>> 
>> So, I need to find out what program/daemon/service trying to communicate with cdc-acm.
>> Is there a simple easy way without recompiling kernel with debug info?
> 
> There are lots of different distros for the Raspberry Pi, I would
> suggest asking on the mailing list of the distro you are using to try to
> determine this, as the people there will be able to help you out the
> best.
> 
> Good luck,
> 
> greg k-h
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Re: Making our own device work under Linux

[Greg KH]

On Fri, Nov 28, 2014 at 02:05:55PM -0500, Dmitriy Fitisov wrote:
> Thank you.
> I registered on a forum, awaited activation.
> Raspberry mailing list is virtually dead, producing a few kilobytes montly.
> But anyway, it is pretty much Debian I would think.

If it is Debian, then try asking on one of the Debian developer mailing
lists.  Either way, it's probably still ModemManager doing this type of
thing, try removing it from your system image and see if that helps.

greg k-h