usb: pl2303: move the two baud rate encoding methods to separate functions

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/pl2303.c

@@ -269,30 +269,18 @@ static int pl2303_set_control_lines(struct usb_serial_port *port, u8 value)
 	return retval;
 }
 
-static void pl2303_encode_baudrate(struct tty_struct *tty,
-					struct usb_serial_port *port,
+static int pl2303_baudrate_encode_direct(int baud, enum pl2303_type type,
 								      u8 buf[4])
 {
-	struct usb_serial *serial = port->serial;
-	struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
-	int baud;
-
-	baud = tty_get_baud_rate(tty);
-	dev_dbg(&port->dev, "baud requested = %d\n", baud);
-	if (!baud)
-		return;
-
-	if (spriv->type != HX || baud <= 115200) {
 	/*
 	 * 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)
 	 */
-		const int baud_sup[] = { 75, 150, 300, 600, 1200, 1800, 2400,
-					 3600, 4800, 7200, 9600, 14400, 19200,
-					 28800, 38400, 57600, 115200, 230400,
-					 460800, 614400, 921600, 1228800,
-					 2457600, 3000000, 6000000 };
+	const int baud_sup[] = { 75, 150, 300, 600, 1200, 1800, 2400, 3600,
+				 4800, 7200, 9600, 14400, 19200, 28800, 38400,
+				 57600, 115200, 230400, 460800, 614400, 921600,
+				 1228800, 2457600, 3000000, 6000000 };
 	int i;
 
 	/* Set baudrate to nearest supported value */
@@ -300,27 +288,28 @@ static void pl2303_encode_baudrate(struct tty_struct *tty,
 		if (baud_sup[i] > baud)
 			break;
 	}
-
 	if (i == ARRAY_SIZE(baud_sup))
 		baud = baud_sup[i - 1];
-		else if (i > 0
-			     && (baud_sup[i] - baud) > (baud - baud_sup[i - 1]))
+	else if (i > 0 && (baud_sup[i] - baud) > (baud - baud_sup[i - 1]))
 		baud = baud_sup[i - 1];
 	else
 		baud = baud_sup[i];
-
 	/* type_0, type_1 only support up to 1228800 baud */
-		if (spriv->type != HX)
+	if (type != HX)
 		baud = min_t(int, baud, 1228800);
-
 	/* Direct (standard) baud rate encoding method */
 	put_unaligned_le32(baud, buf);
-	} else {
+
+	return baud;
+}
+
+static int pl2303_baudrate_encode_divisor(int baud, enum pl2303_type type,
+								      u8 buf[4])
+{
 	/*
 	 * Divisor based baud rate encoding method
 	 *
-		 * NOTE: it's not clear if the type_0/1 chips
-		 * support this method
+	 * NOTE: it's not clear if the type_0/1 chips support this method
 	 *
 	 * divisor = 12MHz * 32 / baudrate = 2^A * B
 	 *
@@ -337,7 +326,7 @@ static void pl2303_encode_baudrate(struct tty_struct *tty,
 
 	/* Respect the specified baud rate limits */
 	baud = max_t(int, baud, 75);
-		if (spriv->type == HX)
+	if (type == HX)
 		baud = min_t(int, baud, 6000000);
 	else
 		baud = min_t(int, baud, 1228800);
@@ -376,8 +365,32 @@ static void pl2303_encode_baudrate(struct tty_struct *tty,
 	if (B <= 8)
 		B = 512;
 	baud = 12000000 * 32 / ((1 << A) * B);
-	}
 
+	return baud;
+}
+
+static void pl2303_encode_baudrate(struct tty_struct *tty,
+					struct usb_serial_port *port,
+					enum pl2303_type type,
+					u8 buf[4])
+{
+	int baud;
+
+	baud = tty_get_baud_rate(tty);
+	dev_dbg(&port->dev, "baud requested = %d\n", baud);
+	if (!baud)
+		return;
+	/*
+	 * There are two methods for setting/encoding the baud rate
+	 * 1) Direct method: encodes the baud rate value directly
+	 *    => supported by all chip types
+	 * 2) Divisor based method: encodes a divisor to a base value (12MHz*32)
+	 *    => supported by HX chips (and likely not by type_0/1 chips)
+	 */
+	if (type != HX || baud <= 115200)
+		baud = pl2303_baudrate_encode_direct(baud, type, buf);
+	else
+		baud = pl2303_baudrate_encode_divisor(baud, type, buf);
 	/* Save resulting baud rate */
 	tty_encode_baud_rate(tty, baud, baud);
 	dev_dbg(&port->dev, "baud set = %d\n", baud);
@@ -434,8 +447,8 @@ static void pl2303_set_termios(struct tty_struct *tty,
 		dev_dbg(&port->dev, "data bits = %d\n", buf[6]);
 	}
 
-	/* For reference buf[0]:buf[3] baud rate value */
-	pl2303_encode_baudrate(tty, port, &buf[0]);
+	/* For reference:   buf[0]:buf[3] baud rate value */
+	pl2303_encode_baudrate(tty, port, spriv->type, buf);
 
 	/* For reference buf[4]=0 is 1 stop bits */
 	/* For reference buf[4]=1 is 1.5 stop bits */