Newbie wants to know the broadcom chip model on router before installation

i have a router which i want to use as bridge but it requires me to know which broadcom chip is built inside the router, how can i identify that? please advise. many thxs in advance.

In short, don't go there.

Either of the three possible options (BCM43222, BCM43217 or BCM43227) is a softmac based Broadcom design, without proper driver support. While there seems to be extremely basic awareness for these chipsets in b43, this is limited to <<54 MBit/s under the best of all circumstances -if at all- and can't be considered stable.

There will neither be any support at all for the embedded xDSL modem.

i know that open-wrt doesn't support adsl function for this model but i am only using it as bridge. thxs...

You should explain what you're actually interested in. My, perhaps naive, interpretation of your question was assuming br-lan, the default bridge between LAN and WLAN - which (mis-)lead(?) me to discuss the extent of wireless support.

The purely ethernet based point of view would be the BCM5325 based ethernet switch, which would be one CPU port connected to the BCM5325 switch. You can assume that this switch is supported and allows independent configuration of the 4 LAN ports (swconfig based VLAN configuration). If you bridge some of them together (which is purely a software feature) after having previously separated them on the switch level would be orthogonal to extent of support for the hardware (albeit performance for this will be limited by the bottleneck of the single CPU port and the SOCs I/O capabilities).