I wrote P4Connect back in 2013 (back then I called it UnityP4). It has since been graciously taken over by Perforce themselves, and you can now download it for free!
P4Connect is the simplest Perforce integration tool for Unity yet. It will:
Allow you to perform all basic version control operations directly from inside Unity.
Show you the list of pending changes.
Let you enter submission notes and diff your files against the Depot.
Automatically check out / move / add / delete files when you make changes in the project view.
Handle project settings and Solution files.