[admin]

To do so add the following code to BeforeAdd/BeforeEdit events (C#):

foreach(var field in values.ToList())
{
     values[field.Key] = field.Value.ToString().ToUpper();
}

return true;

If you also want all text to appear in upper case as it being entered add the following to 'Custom CSS' section in Style Editor.

.rnr-control input, .rnr-control select, .rnr-control textarea 
{ text-transform: uppercase; }