Was Abiathar the father or the son of Ahimelech?

Abiathar was the son of Ahimelech.

And one of the sons of Ahimelech the son of Ahitub, named Abiathar. 1 Samuel 22:20

Abiathar the son of Ahimelech. 1 Samuel 23:6

And David said to Abiathar the priest, Ahimelech's son. 1 Samuel 30:7

Abiathar was the father of Ahimelech.

Ahimelech the son of Abiathar. 2 Samuel 8:17, 1 Chronicles 18:16, 24:6