Linux ACM driver v0.16¶
Copyright (c) 1999 Vojtech Pavlik <firstname.lastname@example.org>
Sponsored by SuSE
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For your convenience, the GNU General Public License version 2 is included in the package: See the file COPYING.
The drivers/usb/class/cdc-acm.c drivers works with USB modems and USB ISDN terminal adapters that conform to the Universal Serial Bus Communication Device Class Abstract Control Model (USB CDC ACM) specification.
Many modems do, here is a list of those I know of:
3Com OfficeConnect 56k
3Com Voice FaxModem Pro
MultiTech MultiModem 56k
Zoom 2986L FaxModem
Compaq 56k FaxModem
ELSA Microlink 56k
I know of one ISDN TA that does work with the acm driver:
3Com USR ISDN Pro TA
Some cell phones also connect via USB. I know the following phones work:
Unfortunately many modems and most ISDN TAs use proprietary interfaces and thus won’t work with this drivers. Check for ACM compliance before buying.
To use the modems you need these modules loaded:
usbcore.ko uhci-hcd.ko ohci-hcd.ko or ehci-hcd.ko cdc-acm.ko
After that, the modem[s] should be accessible. You should be able to use minicom, ppp and mgetty with them.
2. Verifying that it works¶
The first step would be to check /sys/kernel/debug/usb/devices, it should look like this:
T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2 B: Alloc= 0/900 us ( 0%), #Int= 0, #Iso= 0 D: Ver= 1.00 Cls=09(hub ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1 P: Vendor=0000 ProdID=0000 Rev= 0.00 S: Product=USB UHCI Root Hub S: SerialNumber=6800 C:* #Ifs= 1 Cfg#= 1 Atr=40 MxPwr= 0mA I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub E: Ad=81(I) Atr=03(Int.) MxPS= 8 Ivl=255ms T: Bus=01 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#= 2 Spd=12 MxCh= 0 D: Ver= 1.00 Cls=02(comm.) Sub=00 Prot=00 MxPS= 8 #Cfgs= 2 P: Vendor=04c1 ProdID=008f Rev= 2.07 S: Manufacturer=3Com Inc. S: Product=3Com U.S. Robotics Pro ISDN TA S: SerialNumber=UFT53A49BVT7 C: #Ifs= 1 Cfg#= 1 Atr=60 MxPwr= 0mA I: If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=acm E: Ad=85(I) Atr=02(Bulk) MxPS= 64 Ivl= 0ms E: Ad=04(O) Atr=02(Bulk) MxPS= 64 Ivl= 0ms E: Ad=81(I) Atr=03(Int.) MxPS= 16 Ivl=128ms C:* #Ifs= 2 Cfg#= 2 Atr=60 MxPwr= 0mA I: If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=01 Driver=acm E: Ad=81(I) Atr=03(Int.) MxPS= 16 Ivl=128ms I: If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=acm E: Ad=85(I) Atr=02(Bulk) MxPS= 64 Ivl= 0ms E: Ad=04(O) Atr=02(Bulk) MxPS= 64 Ivl= 0ms
The presence of these three lines (and the Cls= ‘comm’ and ‘data’ classes) is important, it means it’s an ACM device. The Driver=acm means the acm driver is used for the device. If you see only Cls=ff(vend.) then you’re out of luck, you have a device with vendor specific-interface:
D: Ver= 1.00 Cls=02(comm.) Sub=00 Prot=00 MxPS= 8 #Cfgs= 2 I: If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=01 Driver=acm I: If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=acm
In the system log you should see:
usb.c: USB new device connect, assigned device number 2 usb.c: kmalloc IF c7691fa0, numif 1 usb.c: kmalloc IF c7b5f3e0, numif 2 usb.c: skipped 4 class/vendor specific interface descriptors usb.c: new device strings: Mfr=1, Product=2, SerialNumber=3 usb.c: USB device number 2 default language ID 0x409 Manufacturer: 3Com Inc. Product: 3Com U.S. Robotics Pro ISDN TA SerialNumber: UFT53A49BVT7 acm.c: probing config 1 acm.c: probing config 2 ttyACM0: USB ACM device acm.c: acm_control_msg: rq: 0x22 val: 0x0 len: 0x0 result: 0 acm.c: acm_control_msg: rq: 0x20 val: 0x0 len: 0x7 result: 7 usb.c: acm driver claimed interface c7b5f3e0 usb.c: acm driver claimed interface c7b5f3f8 usb.c: acm driver claimed interface c7691fa0
If all this seems to be OK, fire up minicom and set it to talk to the ttyACM device and try typing ‘at’. If it responds with ‘OK’, then everything is working.