The USB device code can handle multiple modes:

1) ACM

Emulate a CDC ACM device for modem use by the usb host. Creates a serial device
/dev/usb/acm/*

2) PST

The interface that the Motorola Phone Tools Software (for flash programming,
...) uses.

It creates three misc devices for userspace:

datacmd (read/write)
testcmd (read/write)
datalog (can only be written by userspace)

3) NET

Emulate a usb network device.  Allows TCP/IP communication with the usb host

# cat /proc/usb-functions 
usb-device list

Device descriptor                  12 01 00 02 02 02 00 10 b8 22 0c 60 00 00 03 04 00 01 

Configuration descriptor [1      ] 09 02 5c 00 01 01 05 80 fa 

Interface descriptor     [1:1:0  ] 09 04 00 00 03 02 0a 00 06 
Class descriptor         [1:1:1  ] 05 24 00 10 01 
Class descriptor         [1:1:2  ] 15 24 12 00 01 74 f0 3d bd 1e c1 44 70 a3 67 71 34 c9 f5 54 37 
Class descriptor         [1:1:3  ] 07 24 13 01 00 01 00 
Class descriptor         [1:1:4  ] 0d 24 0f 01 00 00 00 00 ea 05 00 00 00 
Class descriptor         [1:1:5  ] 07 24 0a 00 02 00 00 
Endpint descriptor       [1:1:0:1] 07 05 01 02 40 00 00 
Endpint descriptor       [1:1:0:1] 07 05 82 02 40 00 00 
Endpint descriptor       [1:1:0:1] 07 05 83 03 10 00 0a 

String                   [ 0]      04 09 
String                   [ 1:26]   4eb7ab2026c8
String                   [ 2:14]   (none)
String                   [ 3:18]   Motorola
String                   [ 4:32]   Motorola USBLAN
String                   [ 5:26]   BLAN Net Cfg
String                   [ 6:30]   Comm/Data Intf


4) DSPLOG (implemented as kernel module)

This creates a /dev/dsplog character device.  Userspace programs can write to
that device, and it will be transparently written to a USB endpoint.


5) CFG11 (kernel module)

Composite interface: ACM, test command and MCU data logger

6) Network Monitor Interface (kernel module)

provides cdc-acm and "NM" endpoints.  "NM" endpoint connected to read/write
/dev/nm interface.

7) storage

A usb-storage device