Re: [Linux-usb-users] Stable identification of identical USB hardware

["Kay Sievers" <kay.sievers@vrfy.org>]

On 6/18/07, Greg KH <greg@kroah.com> wrote:
> On Mon, Jun 18, 2007 at 08:35:35AM -0700, Joerg Pommnitz wrote:
> > I want to be able to distinguish between two (or more) mostly
> > identical USB serial devices. The devices in question are UMTS modems.
> > AFAIK they are identical except for the SIM card and the point of
> > attachment. Externally the cards are CardBus devices with an
> > integrated USB host adapter. The actual UMTS device is (internally)
> > connected to the USB host adapter.
> >
> > If I have to cardbus sockets, how do I get from what I know ("the card
> > is in socket 0") to "I have to talk to ttyUSB2 to talk to the card"? I
> > suspect I have to follow the thread from /sys/bus/pci to
> > /sys/bus/usb/devices, but how exactly?
>
> Walk up the "chain" of devices in sysfs and in udev.  The udev man pages
> and documentation should show you how to do this.  If you have specific
> questions about this, please ask them on the linux-hotplug-devel mailing
> list.

This should create a symlink for the serial device in the first slot:
  KERNEL="ttyUSB*", SUBSYSTEMS=="pcmcia", KERNELS=="0.0",
SYMLINK+="serial-slot0"

You find the keys used with udevinfo. Here is an example for a PCMCIA
CF Memory card:
  udevinfo --attribute-walk --name hda4
  ...

  looking at device '/block/hda/hda4':
    KERNEL=="hda4"
    SUBSYSTEM=="block"
  ...

  looking at parent device '/devices/pci0000:00/0000:00:1e.0/0000:04:00.0/0.0':
    KERNELS=="0.0"
    SUBSYSTEMS=="pcmcia"
    DRIVERS=="ide-cs"
  ...

  looking at parent device '/devices/pci0000:00/0000:00:1e.0/0000:04:00.0':
    KERNELS=="0000:04:00.0"
    SUBSYSTEMS=="pci"
    DRIVERS=="yenta_cardbus"
  ...

Kay