Yes, AR 600-20 para 2-2: specifies the following:
Commanders will establish an open door policy within their commands. Soldiers are responsible to ensure that the commander is made aware of problems that affect discipline, morale, and mission effectiveness; and an open door policy allows members of the command to present facts, concerns, and problems of a personal or professional nature or other issues that the Soldier has been unable to resolve. The timing, conduct, and specific procedures of the open door policy are determined by the commander. He or she is responsible for ensuring that Soldiers are aware of the command’s open door policy.