If iI'm try list usb ...
root@truenas[~]# dmesg | grep usb
usbus0: EHCI version 1.0
usbus0 on ehci0
usbus0: 480Mbps High Speed USB v2.0
usbus1: EHCI version 1.0
usbus1 on ehci1
usbus1: 480Mbps High Speed USB v2.0
ugen0.1: <Intel EHCI root HUB> at usbus0
ugen1.1: <Intel EHCI root HUB> at usbus1
Root mount waiting for: CAM usbus0 usbus1
uhub0: <Intel EHCI root HUB, class 9/0, rev 2.00/1.00, addr 1> on usbus0
uhub1: <Intel EHCI root HUB, class 9/0, rev 2.00/1.00, addr 1> on usbus1
Root mount waiting for: CAM usbus0 usbus1
ugen1.2: <vendor 0x8087 product 0x0024> at usbus1
uhub2: <vendor 0x8087 product 0x0024, class 9/0, rev 2.00/0.00, addr 2> on usbus1
ugen0.2: <vendor 0x8087 product 0x0024> at usbus0
uhub3: <vendor 0x8087 product 0x0024, class 9/0, rev 2.00/0.00, addr 2> on usbus0
But from this I'm can't find cc2531 and can't understand device address.