Prevent claiming of novelty usb device by usbhid so I can control it with libusb?

Question

I have a USB rocket launcher that I wish to experiment with through libusb. However, libusb cannot claim the interface; presumably because the output of usb-devices lists 'usbhid' as the driver for the device.

From reading around on the internet, I've only come to the conclusion that I need to detach this driver from the device so I can use it with libusb. However, I have not found a single definitive way to do that, only several different ideas and bug reports.

So, is there a way to detach the usbhid driver from a device that would be relevant with the kernel and tools supplied with Ubuntu 11.04?

EDIT:

I tried creating the file

/etc/udev/rules.d/10-usbhid.rules

and writing the following:

ATTRS{idVendor}=="0a81", ATTRS{idProduct}=="0701", OPTIONS=="ignore_device"

Saving, then rebooting. The file is still there, but it doesn't appear to be working at all.

EDIT:

Okay, I tried this:

sudo -i
echo -n "0003:0A81:0701.0006" > /sys/bus/hid/drivers/generic-usb/unbind

After that, navigating to /sys/bus/hid/devices/0003:0A81:0701.0006 and ls yields:

drwxr-xr-x 2 root root    0 2011-05-29 15:46 power
lrwxrwxrwx 1 root root    0 2011-05-29 13:19 subsystem ->       ../../../../../../../../../bus/hid
-rw-r--r-- 1 root root 4096 2011-05-29 13:19 uevent

It no longer lists a "driver" symlink like it did before, so I would assume that it unbound it. However, all evidence seems to suggest that the driver is still usbhid. For example usb-devices yields:

T:  Bus=02 Lev=03 Prnt=07 Port=00 Cnt=01 Dev#=  9 Spd=1.5 MxCh= 0
D:  Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1
P:  Vendor=0a81 ProdID=0701 Rev=00.01
S:  Manufacturer=Dream Link
S:  Product=USB Missile Launcher v1.0
C:  #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=100mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=03(HID  ) Sub=00 Prot=00 Driver=usbhid

libusb still retuns -1 on usb_claim_interface()....

Answer 1

If you simply run the libusb program as root,

usb_detach_kernel_driver_np()

actually works as expected.

Answer 2

I think you will need to add the device id to udev's blacklist so that no module, including usbhid, gets attached to it.

Answer 3

I think that the following udev rule will do what you want:

SUBSYSTEM=="usb", ATTRS{idVendor}=="0a81", ATTRS{idProduct}=="0701", MODE="0660", GROUP="plugdev", RUN="/bin/sh -c 'echo -n $id:1.0 > /sys/bus/usb/drivers/usbhid/unbind'"

Your user will need to be a member of the plugdev group to gain access. There's no need to run as root with this rule in place.

Answer 4

For me (Debian sid/stretch), the udev $id attribute is empty when I plug in my USB device. It is $kernel that contains the necessary string to pass to USBHID's unbind.

Here are the udev rules that I'm using:

SUBSYSTEM=="usb", ATTRS{idVendor}=="0000", ATTRS{idProduct}=="0000", MODE="0660", GROUP="plugdev"
ATTRS{idVendor}=="0000", ATTRS{idProduct}=="0000", DRIVER="usbhid", RUN="/bin/sh -c 'echo -n $kernel >/sys/bus/usb/drivers/usbhid/unbind'"

Replace the idVendor and idProduct with the IDs of your device, of course.

---

For writing these sorts of rules, the following command will show you all of the attributes you can use (for the given USB device):

udevadm info -a /sys/bus/usb/devices/1-3:1.0/

Finally, $id and $kernel are not shell variables; they are replaced by the udev parser. For a complete list of these variables, man udev and search for %k.