[PATCH] Serial: Add uart_insert_char()

Add uart_insert_char(), which handles inserting characters into the
flip buffer.  This helper function handles the correct semantics
for handling overrun in addition to inserting normal characters.

Signed-off-by: Russell King <rmk@arm.linux.org.uk>
diff --git a/drivers/serial/21285.c b/drivers/serial/21285.c
index 33fbda7..0b10169 100644
--- a/drivers/serial/21285.c
+++ b/drivers/serial/21285.c
@@ -126,18 +126,8 @@
 				flag = TTY_FRAME;
 		}
 
-		if ((rxs & port->ignore_status_mask) == 0) {
-			tty_insert_flip_char(tty, ch, flag);
-		}
-		if ((rxs & RXSTAT_OVERRUN) &&
-		    tty->flip.count < TTY_FLIPBUF_SIZE) {
-			/*
-			 * Overrun is special, since it's reported
-			 * immediately, and doesn't affect the current
-			 * character.
-			 */
-			tty_insert_flip_char(tty, 0, TTY_OVERRUN);
-		}
+		uart_insert_char(port, rxs, RXSTAT_OVERRUN, ch, flag);
+
 		status = *CSR_UARTFLG;
 	}
 	tty_flip_buffer_push(tty);