TTY: serial, document few functions

Just put a kernel-doc comment to uart_change_pm and uart_insert_char.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/tty/serial/serial_core.c

@@ -1822,6 +1822,14 @@ uart_set_options(struct uart_port *port, struct console *co,
 EXPORT_SYMBOL_GPL(uart_set_options);
 #endif /* CONFIG_SERIAL_CORE_CONSOLE */
 
+/**
+ * uart_change_pm - set power state of the port
+ *
+ * @state: port descriptor
+ * @pm_state: new state
+ *
+ * Locking: port->mutex has to be held
+ */
 static void uart_change_pm(struct uart_state *state, int pm_state)
 {
 	struct uart_port *port = state->uart_port;
@@ -2495,6 +2503,18 @@ void uart_handle_cts_change(struct uart_port *uport, unsigned int status)
 }
 EXPORT_SYMBOL_GPL(uart_handle_cts_change);
 
+/**
+ * uart_insert_char - push a char to the uart layer
+ *
+ * User is responsible to call tty_flip_buffer_push when they are done with
+ * insertion.
+ *
+ * @port: corresponding port
+ * @status: state of the serial port RX buffer (LSR for 8250)
+ * @overrun: mask of overrun bits in @status
+ * @ch: character to push
+ * @flag: flag for the character (see TTY_NORMAL and friends)
+ */
 void uart_insert_char(struct uart_port *port, unsigned int status,
 		 unsigned int overrun, unsigned int ch, unsigned int flag)
 {