You can list your USB devices using
lsusb. However, the USB subsystem of controllers, hubs and devices connected to them has the structure of a tree and it would be most convenient to view as such. USBView is a small GTK tool written by kernel developer Greg Kroah-Hartman that shows the topography of the devices connected to your USB subsystem in this tree format.
$ sudo apt install usbview
/sys/kernel/debug/usb/devicesand presents it nicely. Reading this file needs superuser permissions. You can read this information manually too:
$ sudo cat /sys/kernel/debug/usb/devices
$ sudo usbview
In the tree presented by USBView, click on the controllers, hubs and devices connected to them to view information about them.
Some of the information I typically look for:
USB version (2 or 3)
Power needed (in mA)
Tried with: USBView 2.0, Linux 3.13.0-52-generic and Ubuntu 14.04