Django Admin- disable Editing and remove "Save" buttons for a specific model

I have a Django Model which I wish to be only readonly. No adds and edits allowed.

I have marked all fields readonly and overridden has_add_permission in ModelAdmin as:

class SomeModelAdmin(admin.ModelAdmin):
     def has_add_permission(self, request):
        return False

Is there a similar has_edit_permission? Which can be disabled to remove "Save" and "Save and continue" buttons? And replace by a simple "Close and Return" button.

Django Documentation Only mentions only about read only fields not about overriding edit permissions.