Fields Level Permission for Create

What's already Implemeneted is We can define the permission on the fields for read and write as follows
'emp_id':fields.many2one('res.users','Employee escalated',write=["crm.group_crm_user"],read=["crm.group_crm_user","crm.group_crm_manager"]),

but the proble is if we give the only read access and no write access then and only we can create the new record and set the value for that fields even the related user have only read permission

need to makc a changes smoethings like

if Read permission only - then allow to read only
if Write Permission Only then - Allow Write + Read permission
if create Permission Only then - Allow Create + Read

so already developed

read = []
write = []

need to implement
create = []