Can I add location in Photos app

Photos is still in Beta, perhaps this option will be added. So far, there is no mention of this option Apple's information about Photos.

Apple - OS X - Photos Preview

Send feedback with a feature request to Apple. Right now is the best time to ask for features, since the app is still under development.

I've always used external editors to write GPS to the original image files before I imported them to Aperture or iPhoto. I prefer to have the GPS directly in the EXIF data of the original photo. You could add Places to your Photos in iPhoto and only then import them to Photos, until Photos will have more advanced features. iPhoto will remain available during the life cycle of Yosemite at least.

I like JetPhoto Studio. That makes it very easy to read the GPS tracks from my Garmin or AMOD tracker and set the GPS coordinates for all photos from a card at once and write them to RAW files. It is also easy to define new waypoints and write GPS based on a Map . Other than with Aperture or iPhoto I can also add the altitude data and the direction the camera has been pointing.

It can also do reverse geocoding look up the address for a given GPS coordinate and write this to the captions or keywords.

And create lovely maps with photos and tracks.

Here is a link: http://www.jetphotosoft.com/web/home/