USB: pl2303: refactor baud-rate divisor handling

Refactor baud-rate divisor handling.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 394903b..44f4b54 100644 (file)
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -339,6 +339,28 @@ static speed_t pl2303_get_supported_baud_rate(speed_t baud)
        return baud;
 }
 
+static speed_t pl2303_encode_baud_rate_divisor(unsigned char buf[4],
+                                                               speed_t baud)
+{
+       unsigned int tmp;
+
+       /*
+        * Apparently the formula is:
+        * baudrate = 12M * 32 / (2^buf[1]) / buf[0]
+        */
+       tmp = 12000000 * 32 / baud;
+       buf[3] = 0x80;
+       buf[2] = 0;
+       buf[1] = (tmp >= 256);
+       while (tmp >= 256) {
+               tmp >>= 2;
+               buf[1] <<= 1;
+       }
+       buf[0] = tmp;
+
+       return baud;
+}
+
 static void pl2303_encode_baud_rate(struct tty_struct *tty,
                                        struct usb_serial_port *port,
                                        u8 buf[4])
@@ -362,23 +384,10 @@ static void pl2303_encode_baud_rate(struct tty_struct *tty,
         */
        baud = pl2303_get_supported_baud_rate(baud);
 
-       if (baud <= 115200) {
+       if (baud <= 115200)
                put_unaligned_le32(baud, buf);
-       } else {
-               /*
-                * Apparently the formula for higher speeds is:
-                * baudrate = 12M * 32 / (2^buf[1]) / buf[0]
-                */
-               unsigned tmp = 12000000 * 32 / baud;
-               buf[3] = 0x80;
-               buf[2] = 0;
-               buf[1] = (tmp >= 256);
-               while (tmp >= 256) {
-                       tmp >>= 2;
-                       buf[1] <<= 1;
-               }
-               buf[0] = tmp;
-       }
+       else
+               baud = pl2303_encode_baud_rate_divisor(buf, baud);
 
        /* Save resulting baud rate */
        tty_encode_baud_rate(tty, baud, baud);