usbserial: Add support for VW/Skoda "Carstick LTE"

Add support for VW/Skoda "Carstick LTE"

D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=1c9e ProdID=7605 Rev=02.00
S:  Manufacturer=USB Modem
S:  Product=USB Modem
C:  #Ifs= 4 Cfg#= 1 Atr=e0 MxPwr=500mA
I:  If#=0x0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
I:  If#=0x1 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
I:  If#=0x2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
I:  If#=0x3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)

The stick has AT command interfaces on interfaces 1, 2, and 3, and does PPP on interface 3.

---
Note that the patch is untested, I hope that it's trivial enough. I have the device running on a Debian kernel 4.19 by dynamically binding the USB device ID to the option driver.

index ee5ac4e..61b4a46 100644
@@ -406,6 +406,8 @@ static void option_instat_callback(struct urb *urb);
  * It seems to contain a Qualcomm QSC6240/6290 chipset            */
 #define FOUR_G_SYSTEMS_PRODUCT_W14		0x9603
 #define FOUR_G_SYSTEMS_PRODUCT_W100		0x9b01
+/* This one was sold as the VW and Skoda "Carstick LTE" */
+#define FOUR_G_SYSTEMS_PRODUCT_CARSTICK_LTE	0x7605
 
 /* Fujisoft products */
 #define FUJISOFT_PRODUCT_FS040U			0x9b02

@@ -1980,6 +1982,8 @@ static const struct usb_device_id option_ids[] = {
 	  .driver_info = NCTRL(0) | NCTRL(1) },
 	{ USB_DEVICE(LONGCHEER_VENDOR_ID, FOUR_G_SYSTEMS_PRODUCT_W100),
 	  .driver_info = NCTRL(1) | NCTRL(2) | RSVD(3) },
+	{ USB_DEVICE(LONGCHEER_VENDOR_ID, FOUR_G_SYSTEMS_PRODUCT_CARSTICK_LTE),
+	  .driver_info = RSVD(0) },
 	{USB_DEVICE(LONGCHEER_VENDOR_ID, FUJISOFT_PRODUCT_FS040U),
 	 .driver_info = RSVD(3)},
 	{ USB_DEVICE_INTERFACE_CLASS(LONGCHEER_VENDOR_ID, SPEEDUP_PRODUCT_SU9800, 0xff) },

Thanks for the patch. Looks good.

I've applied it now with an updated patch prefix:

USB: serial: option: add support for VW/Skoda "Carstick LTE"

and after moving the new define above the other FOUR_G defines to maintain the sort order (by PID).