Open D5 tuning
The open D5 tuning is a relatively popular tuning and especially a viable choice for acoustic guitar.
based on the D 5th chord and to get the open D tuning on your guitar you tune it like this: D A D D A D. Important: tune down (decrease) the string when re-tune and not the opposite.
An alternative D5 tuning is DADADD, but this string configuration involves much more pressure on the strings with especially the 3rd string three seme-notes up. The chords in this presentation will therefore focus on the DADDAD with the peculiar feature with two D-tuned strings in the middle on the same octave. It's also worth noticing that this is a symmetrical tuning, which among many things result in many fingering choices for the same chords.
Including an octave perspective, the tuning is written D2-A2-D3-D3-A3-D4, meaning that the lowest string is a D note on the second octave, the second lowest string is a A note on the second octave and so on. Standard tuning reference: E2-A2-D3-G3-B3-E4.
D5 can be played in other many ways, including 00XXXX, 000XXX and 0000XX.
Dsus2, D and Dsus4 can likewise be played by fretting any of the open D-strings resulting in different voicings. Also, fingerings such as 002200, 004400 and 005500 could be tried.
Besides from the D chords, it is often difficult to find natural fingerings in open position for relevant chords.
One of the possible ways to play the E minor triad are in barre form: 222422. A major can also be played with a barre shape: X02242.
Progressions in this specific tuning:
D5 - Dsus2 - D - Dsus4 - D5 (000700)