tty: Update serial core API documentation

Signed-off-by: Kevin Cernekee <[e-mail]>
Acked-by: Alan Cox <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/serial/driver

···
 	Interrupts: locally disabled.
 	This call must not sleep
 
+  send_xchar(port,ch)
+	Transmit a high priority character, even if the port is stopped.
+	This is used to implement XON/XOFF flow control and tcflow().  If
+	the serial driver does not implement this function, the tty core
+	will append the character to the circular buffer and then call
+	start_tx() / stop_tx() to flush the data out.
+
+	Locking: none.
+	Interrupts: caller dependent.
+
   stop_rx(port)
 	Stop receiving characters; the port is in the process of
 	being closed.
···
 	Locking: none.
 	Interrupts: caller dependent.
 
+  set_wake(port,state)
+	Enable/disable power management wakeup on serial activity.  Not
+	currently implemented.
+
   type(port)
 	Return a pointer to a string constant describing the specified
 	port, or return NULL, in which case the string 'unknown' is
···
 
 	Locking: none.
 	Interrupts: caller dependent.
+
+  poll_init(port)
+	Called by kgdb to perform the minimal hardware initialization needed
+	to support poll_put_char() and poll_get_char().  Unlike ->startup()
+	this should not request interrupts.
+
+	Locking: tty_mutex and tty_port->mutex taken.
+	Interrupts: n/a.
+
+  poll_put_char(port,ch)
+	Called by kgdb to write a single character directly to the serial
+	port.  It can and should block until there is space in the TX FIFO.
+
+	Locking: none.
+	Interrupts: caller dependent.
+	This call must not sleep
+
+  poll_get_char(port)
+	Called by kgdb to read a single character directly from the serial
+	port.  If data is available, it should be returned; otherwise
+	the function should return NO_POLL_CHAR immediately.
+
+	Locking: none.
+	Interrupts: caller dependent.
+	This call must not sleep
 
 Other functions
 ---------------

include/linux/serial_core.h

···
 struct device;
 
 /*
- * This structure describes all the operations that can be
- * done on the physical hardware.
+ * This structure describes all the operations that can be done on the
+ * physical hardware.  See Documentation/serial/driver for details.
  */
 struct uart_ops {
 	unsigned int	(*tx_empty)(struct uart_port *);
···
 	/*
 	 * Return a string describing the type of the port
 	 */
-	const char *(*type)(struct uart_port *);
+	const char	*(*type)(struct uart_port *);
 
 	/*
 	 * Release IO and memory resources used by the port.
···
 	int		(*ioctl)(struct uart_port *, unsigned int, unsigned long);
 #ifdef CONFIG_CONSOLE_POLL
 	int		(*poll_init)(struct uart_port *);
-	void	(*poll_put_char)(struct uart_port *, unsigned char);
+	void		(*poll_put_char)(struct uart_port *, unsigned char);
 	int		(*poll_get_char)(struct uart_port *);
 #endif
 };