add this to your shell rc file and whenever you are in a subfolder of a git repo, you go back to the git project root directory. "gitroot" called outside a directory as no effect except printing to stdout that you are not currently in a git repo.

gistfile1.txt

# @chgravier <[email protected]>
function gitroot {
        FROM=$( pwd )
        LOOKFOR=".git"
        GITPROJECT=0
        while [ "$(pwd)" != "/" ]
        do
                if [ ! -e $LOOKFOR ];
                then
                        PARENT=$(dirname $( pwd ))
                        chdir $PARENT
                else
                        GITPROJECT=1
                        unset PARENT
                        break;
                fi
        done

        if [ $GITPROJECT -eq 1 ]
        then
                unset FROM
                unset PARENT
                echo "Switched to git project home."
        else
                echo "This is not a git project !"
                cd $FROM
                unset FROM
        fi
}

Ya mean I already had it given I have git zsh plugin ? rofl :)