Basically, you can't have it concealed in a motor vehicle if it's readily accessible.
I would consider locked in the glove box or a carrying case not readily accessible, your mileage may vary
If you are wearing the handgun openlyin a belt holster, it is also considered NOT concealed. Even if you're in a motor vehicle.
There is no notification statute where you have to notify a LEO you have a firearm. so if it's locked in the glove box, you don't have to tell him. However, you may want to keep your registration and proof of insurance somewhere else.
The rest of Oregon's firearms laws are in Chapter 166 of the Oregon Revised Statutes: http://www.leg.state.or.us/ors/166.html
...Hope this helps...