This song was originally written/recorded by Trent Reznor, of NIN...
Johnny covered it on American IV, his new album...it sounds amazing.
Only Johnny Cash could cover a song and make it better...well, actually
I like both versions...they are both brilliant in their own way.

Standard tuning (EADGBE)

Verse: Arpeggiated chords
Am Cm D

Chorus:
G Am F G

And that's really about it...listen to it & play along, you'll get it.
A simple song, but genius nonetheless...