There are a number of mount options for usbfs, which will
be of most interest to you if you need to override the default
access control policy.
That policy is that only root may read or write device files
(/proc/bus/BBB/DDD) although anyone may read
the devices
or drivers files.
I/O requests to the device also need the CAP_SYS_RAWIO capability,
The significance of that is that by default, all user mode device drivers need super-user privileges. You can change modes or ownership in a driver setup when the device hotplugs, or maye just start the driver right then, as a privileged server (or some activity within one). That's the most secure approach for multi-user systems, but for single user systems ("trusted" by that user) it's more convenient just to grant everyone all access (using the devmode=0666 option) so the driver can start whenever it's needed.
The mount options for usbfs, usable in /etc/fstab or in command line invocations of mount, are:
Controls the GID used for the /proc/bus/usb/BBB directories. (Default: 0)
Controls the file mode used for the /proc/bus/usb/BBB directories. (Default: 0555)
Controls the UID used for the /proc/bus/usb/BBB directories. (Default: 0)
Controls the GID used for the /proc/bus/usb/BBB/DDD files. (Default: 0)
Controls the file mode used for the /proc/bus/usb/BBB/DDD files. (Default: 0644)
Controls the UID used for the /proc/bus/usb/BBB/DDD files. (Default: 0)
Controls the GID used for the /proc/bus/usb/devices and drivers files. (Default: 0)
Controls the file mode used for the /proc/bus/usb/devices and drivers files. (Default: 0444)
Controls the UID used for the /proc/bus/usb/devices and drivers files. (Default: 0)
Note that many Linux distributions hard-wire the mount options
for usbfs in their init scripts, such as
/etc/rc.d/rc.sysinit,
rather than making it easy to set this per-system
policy in /etc/fstab.