[PATCH 1/4] tty: omap-serial: pull out calculation from baud_is_mode16

[Frans Klaver <frans.klaver@xsens.com>]

To determine the correct divisor, we need to know the difference between
the desired baud rate and the actual baud rate. The calculation for this
difference is implemented twice within omap_serial_baud_is_mode16().
Pull out the calculation for easier maintenance.

Signed-off-by: Frans Klaver <frans.klaver@xsens.com>
---
 drivers/tty/serial/omap-serial.c | 26 ++++++++++++++++++--------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index d017cec..ae935ce 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -239,6 +239,22 @@ static void serial_omap_enable_wakeup(struct uart_omap_port *up, bool enable)
 }
 
 /*
+ * Calculate the absolute difference between the desired and actual baud
+ * rate for the given mode.
+ */
+static inline int calculate_baud_abs_diff(struct uart_port *port,
+				unsigned int baud, unsigned int mode)
+{
+	unsigned int n = port->uartclk / (mode * baud);
+	int abs_diff = baud - (port->uartclk / (mode * n));
+
+	if (abs_diff < 0)
+		abs_diff = -abs_diff;
+
+	return abs_diff;
+}
+
+/*
  * serial_omap_baud_is_mode16 - check if baud rate is MODE16X
  * @port: uart port info
  * @baud: baudrate for which mode needs to be determined
@@ -252,14 +268,8 @@ static void serial_omap_enable_wakeup(struct uart_omap_port *up, bool enable)
 static bool
 serial_omap_baud_is_mode16(struct uart_port *port, unsigned int baud)
 {
-	unsigned int n13 = port->uartclk / (13 * baud);
-	unsigned int n16 = port->uartclk / (16 * baud);
-	int baudAbsDiff13 = baud - (port->uartclk / (13 * n13));
-	int baudAbsDiff16 = baud - (port->uartclk / (16 * n16));
-	if (baudAbsDiff13 < 0)
-		baudAbsDiff13 = -baudAbsDiff13;
-	if (baudAbsDiff16 < 0)
-		baudAbsDiff16 = -baudAbsDiff16;
+	int baudAbsDiff13 = calculate_baud_abs_diff(port, baud, 13);
+	int baudAbsDiff16 = calculate_baud_abs_diff(port, baud, 16);
 
 	return (baudAbsDiff13 >= baudAbsDiff16);
 }
-- 
1.9.3