forked from Imagelibrary/rtems
Add a new low-level device API to Termios that passes the TTY structure to the low-level device functions. This greatly simplifies the low-level device drivers since they are no longer forced to derive their private data from the minor number. It makes it possible to use the TTY low-level lock in the device driver low-level functions which is necessary for proper SMP support. For example to set the attributes it is often necessary to perform a read-modify-write operation on a control register used also by interrupt routines. A compatibility layer is provided to support device drivers using the old callback functions so it is not necessary to modify existing device drivers.