1                          Linux ACM driver v0.16
   2                 (c) 1999 Vojtech Pavlik <>
   3                             Sponsored by SuSE
   60. Disclaimer
   8  This program is free software; you can redistribute it and/or modify it
   9under the terms of the GNU General Public License as published by the Free
  10Software Foundation; either version 2 of the License, or (at your option)
  11any later version.
  13  This program is distributed in the hope that it will be useful, but
  14WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  15or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  16more details.
  18  You should have received a copy of the GNU General Public License along
  19with this program; if not, write to the Free Software Foundation, Inc., 59
  20Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22  Should you need to contact me, the author, you can do so either by e-mail
  23- mail your message to <>, or by paper mail: Vojtech Pavlik,
  24Ucitelska 1576, Prague 8, 182 00 Czech Republic
  26  For your convenience, the GNU General Public License version 2 is included
  27in the package: See the file COPYING.
  291. Usage
  31  The drivers/usb/class/cdc-acm.c drivers works with USB modems and USB ISDN terminal
  32adapters that conform to the Universal Serial Bus Communication Device Class
  33Abstract Control Model (USB CDC ACM) specification.
  35  Many modems do, here is a list of those I know of:
  37        3Com OfficeConnect 56k
  38        3Com Voice FaxModem Pro
  39        3Com Sportster
  40        MultiTech MultiModem 56k
  41        Zoom 2986L FaxModem
  42        Compaq 56k FaxModem
  43        ELSA Microlink 56k
  45  I know of one ISDN TA that does work with the acm driver:
  47        3Com USR ISDN Pro TA
  49  Some cell phones also connect via USB. I know the following phones work:
  51        SonyEricsson K800i
  53  Unfortunately many modems and most ISDN TAs use proprietary interfaces and
  54thus won't work with this drivers. Check for ACM compliance before buying.
  56  To use the modems you need these modules loaded:
  58        usbcore.ko
  59        uhci-hcd.ko ohci-hcd.ko or ehci-hcd.ko
  60        cdc-acm.ko
  62  After that, the modem[s] should be accessible. You should be able to use
  63minicom, ppp and mgetty with them.
  652. Verifying that it works
  67  The first step would be to check /proc/bus/usb/devices, it should look
  68like this:
  70T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=12  MxCh= 2
  71B:  Alloc=  0/900 us ( 0%), #Int=  0, #Iso=  0
  72D:  Ver= 1.00 Cls=09(hub  ) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1
  73P:  Vendor=0000 ProdID=0000 Rev= 0.00
  74S:  Product=USB UHCI Root Hub
  75S:  SerialNumber=6800
  76C:* #Ifs= 1 Cfg#= 1 Atr=40 MxPwr=  0mA
  77I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
  78E:  Ad=81(I) Atr=03(Int.) MxPS=   8 Ivl=255ms
  79T:  Bus=01 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#=  2 Spd=12  MxCh= 0
  80D:  Ver= 1.00 Cls=02(comm.) Sub=00 Prot=00 MxPS= 8 #Cfgs=  2
  81P:  Vendor=04c1 ProdID=008f Rev= 2.07
  82S:  Manufacturer=3Com Inc.
  83S:  Product=3Com U.S. Robotics Pro ISDN TA
  84S:  SerialNumber=UFT53A49BVT7
  85C:  #Ifs= 1 Cfg#= 1 Atr=60 MxPwr=  0mA
  86I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=acm
  87E:  Ad=85(I) Atr=02(Bulk) MxPS=  64 Ivl=  0ms
  88E:  Ad=04(O) Atr=02(Bulk) MxPS=  64 Ivl=  0ms
  89E:  Ad=81(I) Atr=03(Int.) MxPS=  16 Ivl=128ms
  90C:* #Ifs= 2 Cfg#= 2 Atr=60 MxPwr=  0mA
  91I:  If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=01 Driver=acm
  92E:  Ad=81(I) Atr=03(Int.) MxPS=  16 Ivl=128ms
  93I:  If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=acm
  94E:  Ad=85(I) Atr=02(Bulk) MxPS=  64 Ivl=  0ms
  95E:  Ad=04(O) Atr=02(Bulk) MxPS=  64 Ivl=  0ms
  97The presence of these three lines (and the Cls= 'comm' and 'data' classes)
  98is important, it means it's an ACM device. The Driver=acm means the acm
  99driver is used for the device. If you see only Cls=ff(vend.) then you're out
 100of luck, you have a device with vendor specific-interface.
 102D:  Ver= 1.00 Cls=02(comm.) Sub=00 Prot=00 MxPS= 8 #Cfgs=  2
 103I:  If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=01 Driver=acm
 104I:  If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=acm
 106In the system log you should see:
 108usb.c: USB new device connect, assigned device number 2
 109usb.c: kmalloc IF c7691fa0, numif 1
 110usb.c: kmalloc IF c7b5f3e0, numif 2
 111usb.c: skipped 4 class/vendor specific interface descriptors
 112usb.c: new device strings: Mfr=1, Product=2, SerialNumber=3
 113usb.c: USB device number 2 default language ID 0x409
 114Manufacturer: 3Com Inc.
 115Product: 3Com U.S. Robotics Pro ISDN TA
 116SerialNumber: UFT53A49BVT7
 117acm.c: probing config 1
 118acm.c: probing config 2
 119ttyACM0: USB ACM device
 120acm.c: acm_control_msg: rq: 0x22 val: 0x0 len: 0x0 result: 0
 121acm.c: acm_control_msg: rq: 0x20 val: 0x0 len: 0x7 result: 7
 122usb.c: acm driver claimed interface c7b5f3e0
 123usb.c: acm driver claimed interface c7b5f3f8
 124usb.c: acm driver claimed interface c7691fa0
 126If all this seems to be OK, fire up minicom and set it to talk to the ttyACM
 127device and try typing 'at'. If it responds with 'OK', then everything is
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