USB: pl2303: refactor baud-rate table lookup

Refactor supported baud-rate table lookup.

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

1 files changed, 33 insertions, 22 deletions

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 8d792afbe27f..9a95b92310f2 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -311,31 +311,19 @@ static int pl2303_set_control_lines(struct usb_serial_port *port, u8 value)
         return retval;
 }
 
-static void pl2303_encode_baud_rate(struct tty_struct *tty,
-                                        struct usb_serial_port *port,
-                                        u8 buf[4])
+/*
+ * Returns the nearest supported baud rate.
+ */
+static speed_t pl2303_get_supported_baud_rate(speed_t baud)
 {
-        const speed_t baud_sup[] = { 75, 150, 300, 600, 1200, 1800, 2400, 3600,
-                                 4800, 7200, 9600, 14400, 19200, 28800, 38400,
-                                 57600, 115200, 230400, 460800, 500000, 614400,
-                                 921600, 1228800, 2457600, 3000000, 6000000 };
+        static const speed_t baud_sup[] = {
+                75, 150, 300, 600, 1200, 1800, 2400, 3600, 4800, 7200, 9600,
+                14400, 19200, 28800, 38400, 57600, 115200, 230400, 460800,
+                500000, 614400, 921600, 1228800, 2457600, 3000000, 6000000
+        };
 
-        struct usb_serial *serial = port->serial;
-        struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
-        speed_t baud;
-        int i;
+        unsigned i;
 
-        /*
-         * NOTE: Only the values defined in baud_sup are supported!
-         *       => if unsupported values are set, the PL2303 seems to use
-         *          9600 baud (at least my PL2303X always does)
-         */
-        baud = tty_get_baud_rate(tty);
-        dev_dbg(&port->dev, "baud requested = %u\n", baud);
-        if (!baud)
-                return;
-
-        /* Set baud rate to nearest supported value */
         for (i = 0; i < ARRAY_SIZE(baud_sup); ++i) {
                 if (baud_sup[i] > baud)
                         break;
@@ -348,6 +336,29 @@ static void pl2303_encode_baud_rate(struct tty_struct *tty,
         else
                 baud = baud_sup[i];
 
+        return baud;
+}
+
+static void pl2303_encode_baud_rate(struct tty_struct *tty,
+                                        struct usb_serial_port *port,
+                                        u8 buf[4])
+{
+        struct usb_serial *serial = port->serial;
+        struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
+        speed_t baud;
+
+        baud = tty_get_baud_rate(tty);
+        dev_dbg(&port->dev, "baud requested = %u\n", baud);
+        if (!baud)
+                return;
+        /*
+         * Set baud rate to nearest supported value.
+         *
+         * NOTE: If unsupported values are set directly, the PL2303 seems to
+         *       use 9600 baud.
+         */
+        baud = pl2303_get_supported_baud_rate(baud);
+
         if (spriv->type->max_baud_rate)
                 baud = min_t(speed_t, baud, spriv->type->max_baud_rate);