Merge tag 'usb-serial-4.3-rc1' of...

Merge tag 'usb-serial-4.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial into usb-next

Johan writes:

USB-serial updates for v4.3-rc1

Here's a fix for a long-standing issue with the pl2303 divisor
calculations that affects some non-standard baudrates that were enabled
in v3.18.

Adding support for newer Edgeport devices and firmware required changes
to the io_ti driver and also exposed some issues with the driver's
current firmware handling.

Included is also a URL comment-typo fix.
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/ftdi_sio_ids.h

@@ -1365,7 +1365,7 @@
 #define FTDI_CTI_NANO_PID	0xF60B
 
 /*
- * ZeitControl cardsystems GmbH rfid-readers http://zeitconrol.de
+ * ZeitControl cardsystems GmbH rfid-readers http://zeitcontrol.de
  */
 /* TagTracer MIFARE*/
 #define FTDI_ZEITCONTROL_TAGTRACE_MIFARE_PID	0xF7C0

drivers/usb/serial/pl2303.c

@@ -362,21 +362,38 @@ static speed_t pl2303_encode_baud_rate_direct(unsigned char buf[4],
 static speed_t pl2303_encode_baud_rate_divisor(unsigned char buf[4],
 								speed_t baud)
 {
-	unsigned int tmp;
+	unsigned int baseline, mantissa, exponent;
 
 	/*
 	 * Apparently the formula is:
-	 * baudrate = 12M * 32 / (2^buf[1]) / buf[0]
+	 *   baudrate = 12M * 32 / (mantissa * 4^exponent)
+	 * where
+	 *   mantissa = buf[8:0]
+	 *   exponent = buf[11:9]
 	 */
-	tmp = 12000000 * 32 / baud;
+	baseline = 12000000 * 32;
+	mantissa = baseline / baud;
+	if (mantissa == 0)
+		mantissa = 1;	/* Avoid dividing by zero if baud > 32*12M. */
+	exponent = 0;
+	while (mantissa >= 512) {
+		if (exponent < 7) {
+			mantissa >>= 2;	/* divide by 4 */
+			exponent++;
+		} else {
+			/* Exponent is maxed. Trim mantissa and leave. */
+			mantissa = 511;
+			break;
+		}
+	}
+
 	buf[3] = 0x80;
 	buf[2] = 0;
-	buf[1] = (tmp >= 256);
-	while (tmp >= 256) {
-		tmp >>= 2;
-		buf[1] <<= 1;
-	}
-	buf[0] = tmp;
+	buf[1] = exponent << 1 | mantissa >> 8;
+	buf[0] = mantissa & 0xff;
+
+	/* Calculate and return the exact baud rate. */
+	baud = (baseline / mantissa) >> (exponent << 1);
 
 	return baud;
 }