Here's a snippet from the NRA site:
It is unlawful for any person to carry "with the intent to go armed" a firearm, knife with a blade length exceeding four inches, or a club. The burden is on the state to show an "intent to go armed."
It is a defense to unlawful carrying if the possession or carrying was:
* * *
•By a person authorized by written directive and permit to carry handguns.
So, in TN, you start with the presumption that under TN statute, carrying a handgun is a crime, but various defenses exist. One of those defenses is having a Handgun Carry Permit (HCP). Since possession of a handgun is INITIALLY a crime, then merely seeing you with a visible weapon arguably gives law enforcement reasonable, articulable suspicion that you MAY be committing a crime (carrying of a handgun). Since he cannot eliminate that suspicion without contacting you, thus, LEO in TN have the right to stop you and confirm that you have an HCP, and thus have a valid defense to the charge of carrying a handgun "with intent to go armed" (must flow from Civil War days....).
Presumably, the limits to such a stop would be that LEO can check your HCP for validity (and, I presume, check you for warrants in the course of so doing). I do not believe TN law explicitly permits LEO to disarm you during such a stop, but most of the time, this is overlooked in favor of "officer safety". I'm not agreeing, mind you....
Occasionally, an LEO will want to run the weapon in NCIC to insure it is not stolen. My own personal position is that this is improper, and probably constitutes an illegal search under the 4th Amendment, unless there is some OTHER indicia supporting a suspiction that the firearm is stolen. I have taken recently to covering my weapon's serial number with electrical tape. This way, LEO cannot claim the serial number was in "plain view", thus justifying a search, during which they wrote down the serial number and ran it. Might not be for everyone - that's what I do.
I've never had the experience since moving to TN 16 months ago. Hope I don't. If you choose to OC in TN, just understand you are required to show them your HCP. If they start moving beyond that, of course, it's up to you how far you let it go before you start asking "am I free to leave ???". In the few "stop and ID" incidents I've had in other states, use of those exact words brought the contact to a screeching halt, as the officer realized I knew just a little bit about my rights. Of course, the one time he said "no", that brought out a great big can of Shut The Flame Up on my part.....
Enjoy your stay.