u3g serial device name query

[Milan Obuch]

On Thursday 30 April 2009 12:58:36 Hans Petter Selasky wrote:
> On Thursday 30 April 2009, Milan Obuch wrote:
> > Hi,
> >
> > I have HUAWEI 3g usb modem. It works with u3g from current. There is
> > however one thing I did not get working yet.
> >
> > When device attaches, it is added into tree as u3gN, devd event is sent.
> > It is easily matched with 'device-name "u3g[0-9]"' clause in devd.conf. I
> > can start ppp automatically and it works well, given no other USB serial
> > device is present.
> >
> > If another USB serial device such as uplcom is present, u3g serial ports
> > does not have the same name. I found no way to relate serial device name
> > to this event and looking in source I see no place where it is created. I
> > would like to put a devctl notify call there. This way I could start ppp
> > with correct device name even if there is some other USB serial device.
> >
> > Could someone point me in the right direction?
>
> USB serial devices have their own unit management. There is however a way
> to override the unit number through the "usb2_com_tty_name" callback, which
> requires some code changes to the u3g driver.
>
> All USB modems and serial adapters end up with the same naming
> prefix: /dev/cuaU%d.%d, so the assigned numbers must be serialised.
>
> What we could do is to have a separate naming prefix for 3G modems, and use
> the device_get_unit() for unit number.
>
> See: src/sys/dev/usb/serial and usb_serial.c
>

I looked over usb2_com_attach_tty function in usb_serial.c, and somewhere 
after call to tty_makedev (where a DPRINT is too) I could put a devctl call.

All I need for it would be device name. In /var/log/message file I see a line 
telling 'u3g0 : Found 2 ports' just after usb2_com_attach_tty function is 
called. If you could tell me how I can get 'u3g0' name via sc argument in 
usb2_com_attach_tty function, I can solve this with no other change.

Regards,
Milan