structure:
write() Write a block of characters to the tty device.
- Returns the number of characters accepted.
+ Returns the number of characters accepted. The
+ character buffer passed to this method is already
+ in kernel space.
put_char() Queues a character for writing to the tty device.
If there is no room in the queue, the character is
tty->termios. Previous settings should be passed in
the "old" argument.
+ The API is defined such that the driver should return
+ the actual modes selected. This means that the
+ driver function is responsible for modifying any
+ bits in the request it cannot fulfill to indicate
+ the actual modes being used. A device with no
+ hardware capability for change (eg a USB dongle or
+ virtual port) can provide NULL for this method.
+
throttle() Notify the tty driver that input buffers for the
line discipline are close to full, and it should
somehow signal that no more characters should be