Kernel driver for Topaz Switch uses DSA (Distributed Switch Architecture) API which automatically enable hardware forwarding between witch ports when network interfaces of switch ports are put into kernel bridge. It means that if you use standard linux tools for bridges (e.g. brctl, ip or bridge) and put lan0, lan1, etc. into br0 then kernel transparently enables hardware forwarding between lan0 and lan1 ports without using CPU.
So basically you do not need to do anything, hardware switching is enabled transparently.
As @robb_fr wrote, you can verify it via tcpdump on eth0 (this will show only packets which are going to CPU).
