Hi all,
I've been getting a lot of requests lately to see if Linux supports the
USB to serial device from Silicon Laboratories called the CP2102 chip.
It turns out that the company is claiming Linux support, yet they are
only shipping a binary driver for Red Hat Linux 9.0.
In talking with the company, they insist that they will not release the
source code to this module, and they claim that they are not infringing
on any rights by not doing so. I claim that this is not true, as to
write a usb to serial driver for Linux you have to use the
drivers/usb/serial/usb-serial.h header file which is specifically
licensed under the GPL v2. This file contains inline functions and
structures that all usb-serial drivers need to use in order to work
properly.
In short, there's no way you can write a Linux usb-serial driver, that
uses the usbserial interface, without it being a derived work of other,
GPL only code.
So, they are in violation, so what. Well, I can't do much about this
(due to my employer's rules about suing companies). But I can do my
best to spread the word that the CP2102 device is not supported on
Linux, and should be avoided at all costs by anyone considering such a
device in a future design. I encourage everyone else to help spread
this information too.
If people are looking for a good usb to serial chip that is supported on
Linux, Windows, and OS-X, there's the PL2303 device from Prolific, and
the FTDI-SIO chip, and the MCT-U232 chip. All of these work very well
on Linux, and are fully supported by all distros. I think they even
might be cheaper than the CP2102 device too :)
Oh, and just for fun, attached to this message is the Linux driver that
SiLabs is distributing, if anyone wants to poke around in it. The
tarball contains 2 binary drivers, one of them a version of the
usbserial.c file (which plainly is licensed under the GPL) and a
mcci_usb.o binary driver. Have fun with it, but don't blame me for any
badness that might happen to your box for running it, no one has any way
of knowing exactly what this driver is doing.
So, in conclusion, please stay away from Silicon Laboratories devices,
if you want to run Linux, as they are obviously not supporting Linux in
any way.
thanks,
greg k-h
On Thursday 18 November 2004 12:39pm, Greg KH wrote:
> Hi all,
>
> I've been getting a lot of requests lately to see if Linux supports the
> USB to serial device from Silicon Laboratories called the CP2102 chip.
> It turns out that the company is claiming Linux support, yet they are
> only shipping a binary driver for Red Hat Linux 9.0.
>
> In talking with the company, they insist that they will not release the
> source code to this module, and they claim that they are not infringing
> on any rights by not doing so.
(... snip ...)
> So, they are in violation, so what. Well, I can't do much about this
> (due to my employer's rules about suing companies). But I can do my
> best to spread the word that the CP2102 device is not supported on
> Linux, and should be avoided at all costs by anyone considering such a
> device in a future design. I encourage everyone else to help spread
> this information too.
(... snip ...)
> So, in conclusion, please stay away from Silicon Laboratories devices,
> if you want to run Linux, as they are obviously not supporting Linux in
> any way.
If anyone has the USB Vendor/Product IDs (VID/PID) for these errant devices, a
negative report (maybe including a link back to Greg's post in the
Linux-USB-Devel list archives [http://
marc.theaimsgroup.com/?l=linux-usb-devel&m=110079963113076&w=2]) should be
submitted to the USB 'Working Devices' list for RS-232/USB adapters at:
http://www.qbik.ch/usb/devices/showdevcat.php?id=12
(I just did a search at that location for 'CP2102' and 'Silicon' and 'SiLabs'
and found no entries for any such devices. I don't see any USB VID/PID info
about them or their devices in the 'usb.ids' file either.)
That might help keep future users away from the devices of a company with such
a poorly-thought-out policy.
Thank you, Greg, for alerting us to this situation.
Bill Marr
Back in November of last year, I wrote about how SiLabs were
distributing a binary only version of a usb-serial driver for Linux that
was violating the GPL <http://thread.gmane.org/gmane.linux.kernel/256403>
Well, it looks like SiLabs and MCCI have finally released the source
code to their driver, but in obfuscated form. I've attached the .zip
file to this message so that everyone can see this horrible nightmare of
a "driver". As per the GPL, they are still violating the license as
obfuscated code releases is not allowed. And as such, they are still
violating my copyright, and the copyrights of a few other kernel
developers.
So, just to re-iterate, I very soundly do not recommend ever buying any
devices from this company, as if this is the way they treat well
established legal issues, who know what else they have done...
Oh, and if you don't want to go through the trouble of opening up the
zip file, I've included inline their header file, in all of it's glory,
with no changes made by me at all, below.
And yes, if you notice the 2.6 kernel does now support this device, but
that is because of some people reverse engineering the device. It was
by no help of the company involved (when seeing this code, those
developers just laughed and said it would be more work to try to read it
than to finish up the driver itself.)
thanks,
greg k-h
-------------------- actual .h file is below -------
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Hi Greg.
> Back in November of last year, I wrote about how SiLabs were
> distributing a binary only version of a usb-serial driver for Linux that
> was violating the GPL <http://thread.gmane.org/gmane.linux.kernel/256403>
>
> Well, it looks like SiLabs and MCCI have finally released the source
> code to their driver, but in obfuscated form. I've attached the .zip
> file to this message so that everyone can see this horrible nightmare of
> a "driver". As per the GPL, they are still violating the license as
> obfuscated code releases is not allowed. And as such, they are still
> violating my copyright, and the copyrights of a few other kernel
> developers.
>
> So, just to re-iterate, I very soundly do not recommend ever buying any
> devices from this company, as if this is the way they treat well
> established legal issues, who know what else they have done...
>
> Oh, and if you don't want to go through the trouble of opening up the
> zip file, I've included inline their header file, in all of it's glory,
> with no changes made by me at all, below.
>
> And yes, if you notice the 2.6 kernel does now support this device, but
> that is because of some people reverse engineering the device. It was
> by no help of the company involved (when seeing this code, those
> developers just laughed and said it would be more work to try to read it
> than to finish up the driver itself.)
Is this for real? What exactly do they think they're trying to pull
here?
I've seen borderline violations but this .. this .. this ..
If the .h file was bad, the .c's are worse.
// Stefan
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On Wed, May 18, 2005 at 08:00:05PM +0200, Stefan Smietanowski wrote:
> Is this for real? What exactly do they think they're trying to pull
> here?
Yes this is for real, and I have no idea what they are trying to do.
> I've seen borderline violations but this .. this .. this ..
>
> If the .h file was bad, the .c's are worse.
Yes it is. And because of this I know of at least one company that has
switched their hardware design away from using this chip already.
Hopefully everyone else will do the same (with the prolifieration of
cheap, usb to serial chips, that work well with Linux, there is no
reason anyone should use this device.)
thanks,
greg k-h