linux/Documentation/usb/acm.txt
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   1                          Linux ACM driver v0.16
   2                 (c) 1999 Vojtech Pavlik <vojtech@suse.cz>
   3                             Sponsored by SuSE
   4----------------------------------------------------------------------------
   5
   60. Disclaimer
   7~~~~~~~~~~~~~
   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.
  12
  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.
  17
  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
  21
  22  Should you need to contact me, the author, you can do so either by e-mail
  23- mail your message to <vojtech@suse.cz>, or by paper mail: Vojtech Pavlik,
  24Ucitelska 1576, Prague 8, 182 00 Czech Republic
  25
  26  For your convenience, the GNU General Public License version 2 is included
  27in the package: See the file COPYING.
  28
  291. Usage
  30~~~~~~~~
  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.
  34
  35  Many modems do, here is a list of those I know of:
  36
  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
  44
  45  I know of one ISDN TA that does work with the acm driver:
  46
  47        3Com USR ISDN Pro TA
  48
  49  Unfortunately many modems and most ISDN TAs use proprietary interfaces and
  50thus won't work with this drivers. Check for ACM compliance before buying.
  51
  52  The driver (with devfs) creates these devices in /dev/usb/acm:
  53
  54        crw-r--r--   1 root     root     166,   0 Apr  1 10:49 0
  55        crw-r--r--   1 root     root     166,   1 Apr  1 10:49 1
  56        crw-r--r--   1 root     root     166,   2 Apr  1 10:49 2
  57
  58  And so on, up to 31, with the limit being possible to change in acm.c to up
  59to 256, so you can use up to 256 USB modems with one computer (you'll need
  60three USB cards for that, though).
  61
  62  If you don't use devfs, then you can create device nodes with the same
  63minor/major numbers anywhere you want, but either the above location or
  64/dev/usb/ttyACM0 is preferred.
  65
  66  To use the modems you need these modules loaded:
  67
  68        usbcore.ko
  69        uhci-hcd.ko ohci-hcd.ko or ehci-hcd.ko
  70        cdc-acm.ko
  71
  72  After that, the modem[s] should be accessible. You should be able to use
  73minicom, ppp and mgetty with them.
  74
  752. Verifying that it works
  76~~~~~~~~~~~~~~~~~~~~~~~~~~
  77  The first step would be to check /proc/bus/usb/devices, it should look
  78like this:
  79
  80T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=12  MxCh= 2
  81B:  Alloc=  0/900 us ( 0%), #Int=  0, #Iso=  0
  82D:  Ver= 1.00 Cls=09(hub  ) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1
  83P:  Vendor=0000 ProdID=0000 Rev= 0.00
  84S:  Product=USB UHCI Root Hub
  85S:  SerialNumber=6800
  86C:* #Ifs= 1 Cfg#= 1 Atr=40 MxPwr=  0mA
  87I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
  88E:  Ad=81(I) Atr=03(Int.) MxPS=   8 Ivl=255ms
  89T:  Bus=01 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#=  2 Spd=12  MxCh= 0
  90D:  Ver= 1.00 Cls=02(comm.) Sub=00 Prot=00 MxPS= 8 #Cfgs=  2
  91P:  Vendor=04c1 ProdID=008f Rev= 2.07
  92S:  Manufacturer=3Com Inc.
  93S:  Product=3Com U.S. Robotics Pro ISDN TA
  94S:  SerialNumber=UFT53A49BVT7
  95C:  #Ifs= 1 Cfg#= 1 Atr=60 MxPwr=  0mA
  96I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=acm
  97E:  Ad=85(I) Atr=02(Bulk) MxPS=  64 Ivl=  0ms
  98E:  Ad=04(O) Atr=02(Bulk) MxPS=  64 Ivl=  0ms
  99E:  Ad=81(I) Atr=03(Int.) MxPS=  16 Ivl=128ms
 100C:* #Ifs= 2 Cfg#= 2 Atr=60 MxPwr=  0mA
 101I:  If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=01 Driver=acm
 102E:  Ad=81(I) Atr=03(Int.) MxPS=  16 Ivl=128ms
 103I:  If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=acm
 104E:  Ad=85(I) Atr=02(Bulk) MxPS=  64 Ivl=  0ms
 105E:  Ad=04(O) Atr=02(Bulk) MxPS=  64 Ivl=  0ms
 106
 107The presence of these three lines (and the Cls= 'comm' and 'data' classes)
 108is important, it means it's an ACM device. The Driver=acm means the acm
 109driver is used for the device. If you see only Cls=ff(vend.) then you're out
 110of luck, you have a device with vendor specific-interface.
 111
 112D:  Ver= 1.00 Cls=02(comm.) Sub=00 Prot=00 MxPS= 8 #Cfgs=  2
 113I:  If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=01 Driver=acm
 114I:  If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=acm
 115
 116In the system log you should see:
 117
 118usb.c: USB new device connect, assigned device number 2
 119usb.c: kmalloc IF c7691fa0, numif 1
 120usb.c: kmalloc IF c7b5f3e0, numif 2
 121usb.c: skipped 4 class/vendor specific interface descriptors
 122usb.c: new device strings: Mfr=1, Product=2, SerialNumber=3
 123usb.c: USB device number 2 default language ID 0x409
 124Manufacturer: 3Com Inc.
 125Product: 3Com U.S. Robotics Pro ISDN TA
 126SerialNumber: UFT53A49BVT7
 127acm.c: probing config 1
 128acm.c: probing config 2
 129ttyACM0: USB ACM device
 130acm.c: acm_control_msg: rq: 0x22 val: 0x0 len: 0x0 result: 0
 131acm.c: acm_control_msg: rq: 0x20 val: 0x0 len: 0x7 result: 7
 132usb.c: acm driver claimed interface c7b5f3e0
 133usb.c: acm driver claimed interface c7b5f3f8
 134usb.c: acm driver claimed interface c7691fa0
 135
 136If all this seems to be OK, fire up minicom and set it to talk to the ttyACM
 137device and try typing 'at'. If it responds with 'OK', then everything is
 138working.
 139
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