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>

3 files changed, 240 insertions, 76 deletions

diff --git a/drivers/usb/serial/ftdi_sio_ids.h b/drivers/usb/serial/ftdi_sio_ids.h
index 792e054..cb12b31 100644
--- a/drivers/usb/serial/ftdi_sio_ids.h
+++ b/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
diff --git a/drivers/usb/serial/io_ti.c b/drivers/usb/serial/io_ti.c
index ddbb8fe..0ac1b10 100644
--- a/drivers/usb/serial/io_ti.c
+++ b/drivers/usb/serial/io_ti.c
@@ -71,6 +71,25 @@ struct product_info {
 	__u8	hardware_type;		/* Type of hardware */
 } __attribute__((packed));
 
+/*
+ * Edgeport firmware header
+ *
+ * "build_number" has been set to 0 in all three of the images I have
+ * seen, and Digi Tech Support suggests that it is safe to ignore it.
+ *
+ * "length" is the number of bytes of actual data following the header.
+ *
+ * "checksum" is the low order byte resulting from adding the values of
+ * all the data bytes.
+ */
+struct edgeport_fw_hdr {
+	u8 major_version;
+	u8 minor_version;
+	__le16 build_number;
+	__le16 length;
+	u8 checksum;
+} __packed;
+
 struct edgeport_port {
 	__u16 uart_base;
 	__u16 dma_address;
@@ -101,6 +120,9 @@ struct edgeport_serial {
 	struct mutex es_lock;
 	int num_ports_open;
 	struct usb_serial *serial;
+	struct delayed_work heartbeat_work;
+	int fw_version;
+	bool use_heartbeat;
 };
 
 
@@ -187,10 +209,6 @@ static const struct usb_device_id id_table_combined[] = {
 
 MODULE_DEVICE_TABLE(usb, id_table_combined);
 
-static unsigned char OperationalMajorVersion;
-static unsigned char OperationalMinorVersion;
-static unsigned short OperationalBuildNumber;
-
 static int closing_wait = EDGE_CLOSING_WAIT;
 static bool ignore_cpu_rev;
 static int default_uart_mode;		/* RS232 */
@@ -209,6 +227,26 @@ static void edge_send(struct usb_serial_port *port, struct tty_struct *tty);
 static int edge_create_sysfs_attrs(struct usb_serial_port *port);
 static int edge_remove_sysfs_attrs(struct usb_serial_port *port);
 
+/*
+ * Some release of Edgeport firmware "down3.bin" after version 4.80
+ * introduced code to automatically disconnect idle devices on some
+ * Edgeport models after periods of inactivity, typically ~60 seconds.
+ * This occurs without regard to whether ports on the device are open
+ * or not.  Digi International Tech Support suggested:
+ *
+ * 1.  Adding driver "heartbeat" code to reset the firmware timer by
+ *     requesting a descriptor record every 15 seconds, which should be
+ *     effective with newer firmware versions that require it, and benign
+ *     with older versions that do not. In practice 40 seconds seems often
+ *     enough.
+ * 2.  The heartbeat code is currently required only on Edgeport/416 models.
+ */
+#define FW_HEARTBEAT_VERSION_CUTOFF ((4 << 8) + 80)
+#define FW_HEARTBEAT_SECS 40
+
+/* Timeouts in msecs: firmware downloads take longer */
+#define TI_VSEND_TIMEOUT_DEFAULT 1000
+#define TI_VSEND_TIMEOUT_FW_DOWNLOAD 10000
 
 static int ti_vread_sync(struct usb_device *dev, __u8 request,
 				__u16 value, __u16 index, u8 *data, int size)
@@ -228,14 +266,14 @@ static int ti_vread_sync(struct usb_device *dev, __u8 request,
 	return 0;
 }
 
-static int ti_vsend_sync(struct usb_device *dev, __u8 request,
-				__u16 value, __u16 index, u8 *data, int size)
+static int ti_vsend_sync(struct usb_device *dev, u8 request, u16 value,
+		u16 index, u8 *data, int size, int timeout)
 {
 	int status;
 
 	status = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
 			(USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT),
-			value, index, data, size, 1000);
+			value, index, data, size, timeout);
 	if (status < 0)
 		return status;
 	if (status != size) {
@@ -250,7 +288,8 @@ static int send_cmd(struct usb_device *dev, __u8 command,
 				__u8 moduleid, __u16 value, u8 *data,
 				int size)
 {
-	return ti_vsend_sync(dev, command, value, moduleid, data, size);
+	return ti_vsend_sync(dev, command, value, moduleid, data, size,
+			TI_VSEND_TIMEOUT_DEFAULT);
 }
 
 /* clear tx/rx buffers and fifo in TI UMP */
@@ -378,9 +417,9 @@ static int write_boot_mem(struct edgeport_serial *serial,
 	}
 
 	for (i = 0; i < length; ++i) {
-		status = ti_vsend_sync(serial->serial->dev,
-				UMPC_MEMORY_WRITE, buffer[i],
-				(__u16)(i + start_address), NULL, 0);
+		status = ti_vsend_sync(serial->serial->dev, UMPC_MEMORY_WRITE,
+				buffer[i], (u16)(i + start_address), NULL,
+				0, TI_VSEND_TIMEOUT_DEFAULT);
 		if (status)
 			return status;
 	}
@@ -421,10 +460,9 @@ static int write_i2c_mem(struct edgeport_serial *serial,
 	 *       regardless of host byte order.
 	 */
 	be_start_address = swab16((u16)start_address);
-	status = ti_vsend_sync(serial->serial->dev,
-				UMPC_MEMORY_WRITE, (__u16)address_type,
-				be_start_address,
-				buffer,	write_length);
+	status = ti_vsend_sync(serial->serial->dev, UMPC_MEMORY_WRITE,
+				(u16)address_type, be_start_address,
+				buffer,	write_length, TI_VSEND_TIMEOUT_DEFAULT);
 	if (status) {
 		dev_dbg(dev, "%s - ERROR %d\n", __func__, status);
 		return status;
@@ -454,9 +492,8 @@ static int write_i2c_mem(struct edgeport_serial *serial,
 		 */
 		be_start_address = swab16((u16)start_address);
 		status = ti_vsend_sync(serial->serial->dev, UMPC_MEMORY_WRITE,
-				(__u16)address_type,
-				be_start_address,
-				buffer, write_length);
+				(u16)address_type, be_start_address, buffer,
+				write_length, TI_VSEND_TIMEOUT_DEFAULT);
 		if (status) {
 			dev_err(dev, "%s - ERROR %d\n", __func__, status);
 			return status;
@@ -748,18 +785,17 @@ exit:
 }
 
 /* Build firmware header used for firmware update */
-static int build_i2c_fw_hdr(__u8 *header, struct device *dev)
+static int build_i2c_fw_hdr(u8 *header, struct device *dev,
+		const struct firmware *fw)
 {
 	__u8 *buffer;
 	int buffer_size;
 	int i;
-	int err;
 	__u8 cs = 0;
 	struct ti_i2c_desc *i2c_header;
 	struct ti_i2c_image_header *img_header;
 	struct ti_i2c_firmware_rec *firmware_rec;
-	const struct firmware *fw;
-	const char *fw_name = "edgeport/down3.bin";
+	struct edgeport_fw_hdr *fw_hdr = (struct edgeport_fw_hdr *)fw->data;
 
 	/* In order to update the I2C firmware we must change the type 2 record
 	 * to type 0xF2.  This will force the UMP to come up in Boot Mode.
@@ -782,24 +818,11 @@ static int build_i2c_fw_hdr(__u8 *header, struct device *dev)
 	// Set entire image of 0xffs
 	memset(buffer, 0xff, buffer_size);
 
-	err = request_firmware(&fw, fw_name, dev);
-	if (err) {
-		dev_err(dev, "Failed to load image \"%s\" err %d\n",
-			fw_name, err);
-		kfree(buffer);
-		return err;
-	}
-
-	/* Save Download Version Number */
-	OperationalMajorVersion = fw->data[0];
-	OperationalMinorVersion = fw->data[1];
-	OperationalBuildNumber = fw->data[2] | (fw->data[3] << 8);
-
 	/* Copy version number into firmware record */
 	firmware_rec = (struct ti_i2c_firmware_rec *)buffer;
 
-	firmware_rec->Ver_Major	= OperationalMajorVersion;
-	firmware_rec->Ver_Minor	= OperationalMinorVersion;
+	firmware_rec->Ver_Major	= fw_hdr->major_version;
+	firmware_rec->Ver_Minor	= fw_hdr->minor_version;
 
 	/* Pointer to fw_down memory image */
 	img_header = (struct ti_i2c_image_header *)&fw->data[4];
@@ -808,8 +831,6 @@ static int build_i2c_fw_hdr(__u8 *header, struct device *dev)
 		&fw->data[4 + sizeof(struct ti_i2c_image_header)],
 		le16_to_cpu(img_header->Length));
 
-	release_firmware(fw);
-
 	for (i=0; i < buffer_size; i++) {
 		cs = (__u8)(cs + buffer[i]);
 	}
@@ -823,8 +844,8 @@ static int build_i2c_fw_hdr(__u8 *header, struct device *dev)
 	i2c_header->Type	= I2C_DESC_TYPE_FIRMWARE_BLANK;
 	i2c_header->Size	= cpu_to_le16(buffer_size);
 	i2c_header->CheckSum	= cs;
-	firmware_rec->Ver_Major	= OperationalMajorVersion;
-	firmware_rec->Ver_Minor	= OperationalMinorVersion;
+	firmware_rec->Ver_Major	= fw_hdr->major_version;
+	firmware_rec->Ver_Minor	= fw_hdr->minor_version;
 
 	return 0;
 }
@@ -925,13 +946,49 @@ static int ti_cpu_rev(struct edge_ti_manuf_descriptor *desc)
 	return TI_GET_CPU_REVISION(desc->CpuRev_BoardRev);
 }
 
+static int check_fw_sanity(struct edgeport_serial *serial,
+		const struct firmware *fw)
+{
+	u16 length_total;
+	u8 checksum = 0;
+	int pos;
+	struct device *dev = &serial->serial->interface->dev;
+	struct edgeport_fw_hdr *fw_hdr = (struct edgeport_fw_hdr *)fw->data;
+
+	if (fw->size < sizeof(struct edgeport_fw_hdr)) {
+		dev_err(dev, "incomplete fw header\n");
+		return -EINVAL;
+	}
+
+	length_total = le16_to_cpu(fw_hdr->length) +
+			sizeof(struct edgeport_fw_hdr);
+
+	if (fw->size != length_total) {
+		dev_err(dev, "bad fw size (expected: %u, got: %zu)\n",
+				length_total, fw->size);
+		return -EINVAL;
+	}
+
+	for (pos = sizeof(struct edgeport_fw_hdr); pos < fw->size; ++pos)
+		checksum += fw->data[pos];
+
+	if (checksum != fw_hdr->checksum) {
+		dev_err(dev, "bad fw checksum (expected: 0x%x, got: 0x%x)\n",
+				fw_hdr->checksum, checksum);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /**
  * DownloadTIFirmware - Download run-time operating firmware to the TI5052
  *
  * This routine downloads the main operating code into the TI5052, using the
  * boot code already burned into E2PROM or ROM.
  */
-static int download_fw(struct edgeport_serial *serial)
+static int download_fw(struct edgeport_serial *serial,
+		const struct firmware *fw)
 {
 	struct device *dev = &serial->serial->dev->dev;
 	int status = 0;
@@ -940,6 +997,14 @@ static int download_fw(struct edgeport_serial *serial)
 	struct usb_interface_descriptor *interface;
 	int download_cur_ver;
 	int download_new_ver;
+	struct edgeport_fw_hdr *fw_hdr = (struct edgeport_fw_hdr *)fw->data;
+
+	if (check_fw_sanity(serial, fw))
+		return -EINVAL;
+
+	/* If on-board version is newer, "fw_version" will be updated below. */
+	serial->fw_version = (fw_hdr->major_version << 8) +
+			fw_hdr->minor_version;
 
 	/* This routine is entered by both the BOOT mode and the Download mode
 	 * We can determine which code is running by the reading the config
@@ -1047,14 +1112,13 @@ static int download_fw(struct edgeport_serial *serial)
 			   version in I2c */
 			download_cur_ver = (firmware_version->Ver_Major << 8) +
 					   (firmware_version->Ver_Minor);
-			download_new_ver = (OperationalMajorVersion << 8) +
-					   (OperationalMinorVersion);
+			download_new_ver = (fw_hdr->major_version << 8) +
+					   (fw_hdr->minor_version);
 
 			dev_dbg(dev, "%s - >> FW Versions Device %d.%d  Driver %d.%d\n",
 				__func__, firmware_version->Ver_Major,
 				firmware_version->Ver_Minor,
-				OperationalMajorVersion,
-				OperationalMinorVersion);
+				fw_hdr->major_version, fw_hdr->minor_version);
 
 			/* Check if we have an old version in the I2C and
 			   update if necessary */
@@ -1063,8 +1127,8 @@ static int download_fw(struct edgeport_serial *serial)
 					__func__,
 					firmware_version->Ver_Major,
 					firmware_version->Ver_Minor,
-					OperationalMajorVersion,
-					OperationalMinorVersion);
+					fw_hdr->major_version,
+					fw_hdr->minor_version);
 
 				record = kmalloc(1, GFP_KERNEL);
 				if (!record) {
@@ -1129,7 +1193,8 @@ static int download_fw(struct edgeport_serial *serial)
 				/* Reset UMP -- Back to BOOT MODE */
 				status = ti_vsend_sync(serial->serial->dev,
 						UMPC_HARDWARE_RESET,
-						0, 0, NULL, 0);
+						0, 0, NULL, 0,
+						TI_VSEND_TIMEOUT_DEFAULT);
 
 				dev_dbg(dev, "%s - HARDWARE RESET return %d\n", __func__, status);
 
@@ -1139,6 +1204,9 @@ static int download_fw(struct edgeport_serial *serial)
 				kfree(rom_desc);
 				kfree(ti_manuf_desc);
 				return -ENODEV;
+			} else {
+				/* Same or newer fw version is already loaded */
+				serial->fw_version = download_cur_ver;
 			}
 			kfree(firmware_version);
 		}
@@ -1177,7 +1245,7 @@ static int download_fw(struct edgeport_serial *serial)
 			 * UMP Ram to I2C and the firmware will update the
 			 * record type from 0xf2 to 0x02.
 			 */
-			status = build_i2c_fw_hdr(header, dev);
+			status = build_i2c_fw_hdr(header, dev, fw);
 			if (status) {
 				kfree(vheader);
 				kfree(header);
@@ -1229,7 +1297,9 @@ static int download_fw(struct edgeport_serial *serial)
 
 			/* Tell firmware to copy download image into I2C */
 			status = ti_vsend_sync(serial->serial->dev,
-					UMPC_COPY_DNLD_TO_I2C, 0, 0, NULL, 0);
+					UMPC_COPY_DNLD_TO_I2C,
+					0, 0, NULL, 0,
+					TI_VSEND_TIMEOUT_FW_DOWNLOAD);
 
 		  	dev_dbg(dev, "%s - Update complete 0x%x\n", __func__, status);
 			if (status) {
@@ -1278,9 +1348,6 @@ static int download_fw(struct edgeport_serial *serial)
 		__u8 cs = 0;
 		__u8 *buffer;
 		int buffer_size;
-		int err;
-		const struct firmware *fw;
-		const char *fw_name = "edgeport/down3.bin";
 
 		/* Validate Hardware version number
 		 * Read Manufacturing Descriptor from TI Based Edgeport
@@ -1328,16 +1395,7 @@ static int download_fw(struct edgeport_serial *serial)
 
 		/* Initialize the buffer to 0xff (pad the buffer) */
 		memset(buffer, 0xff, buffer_size);
-
-		err = request_firmware(&fw, fw_name, dev);
-		if (err) {
-			dev_err(dev, "Failed to load image \"%s\" err %d\n",
-				fw_name, err);
-			kfree(buffer);
-			return err;
-		}
 		memcpy(buffer, &fw->data[4], fw->size - 4);
-		release_firmware(fw);
 
 		for (i = sizeof(struct ti_i2c_image_header);
 				i < buffer_size; i++) {
@@ -1352,7 +1410,9 @@ static int download_fw(struct edgeport_serial *serial)
 		header->CheckSum = cs;
 
 		/* Download the operational code  */
-		dev_dbg(dev, "%s - Downloading operational code image (TI UMP)\n", __func__);
+		dev_dbg(dev, "%s - Downloading operational code image version %d.%d (TI UMP)\n",
+				__func__,
+				fw_hdr->major_version, fw_hdr->minor_version);
 		status = download_code(serial, buffer, buffer_size);
 
 		kfree(buffer);
@@ -2373,10 +2433,44 @@ static void edge_break(struct tty_struct *tty, int break_state)
 			__func__, status);
 }
 
+static void edge_heartbeat_schedule(struct edgeport_serial *edge_serial)
+{
+	if (!edge_serial->use_heartbeat)
+		return;
+
+	schedule_delayed_work(&edge_serial->heartbeat_work,
+			FW_HEARTBEAT_SECS * HZ);
+}
+
+static void edge_heartbeat_work(struct work_struct *work)
+{
+	struct edgeport_serial *serial;
+	struct ti_i2c_desc *rom_desc;
+
+	serial = container_of(work, struct edgeport_serial,
+			heartbeat_work.work);
+
+	rom_desc = kmalloc(sizeof(*rom_desc), GFP_KERNEL);
+
+	/* Descriptor address request is enough to reset the firmware timer */
+	if (!rom_desc || !get_descriptor_addr(serial, I2C_DESC_TYPE_ION,
+			rom_desc)) {
+		dev_err(&serial->serial->interface->dev,
+				"%s - Incomplete heartbeat\n", __func__);
+	}
+	kfree(rom_desc);
+
+	edge_heartbeat_schedule(serial);
+}
+
 static int edge_startup(struct usb_serial *serial)
 {
 	struct edgeport_serial *edge_serial;
 	int status;
+	const struct firmware *fw;
+	const char *fw_name = "edgeport/down3.bin";
+	struct device *dev = &serial->interface->dev;
+	u16 product_id;
 
 	/* create our private serial structure */
 	edge_serial = kzalloc(sizeof(struct edgeport_serial), GFP_KERNEL);
@@ -2387,12 +2481,35 @@ static int edge_startup(struct usb_serial *serial)
 	edge_serial->serial = serial;
 	usb_set_serial_data(serial, edge_serial);
 
-	status = download_fw(edge_serial);
+	status = request_firmware(&fw, fw_name, dev);
 	if (status) {
+		dev_err(dev, "Failed to load image \"%s\" err %d\n",
+				fw_name, status);
 		kfree(edge_serial);
 		return status;
 	}
 
+	status = download_fw(edge_serial, fw);
+	release_firmware(fw);
+	if (status) {
+		kfree(edge_serial);
+		return status;
+	}
+
+	product_id = le16_to_cpu(
+			edge_serial->serial->dev->descriptor.idProduct);
+
+	/* Currently only the EP/416 models require heartbeat support */
+	if (edge_serial->fw_version > FW_HEARTBEAT_VERSION_CUTOFF) {
+		if (product_id == ION_DEVICE_ID_TI_EDGEPORT_416 ||
+			product_id == ION_DEVICE_ID_TI_EDGEPORT_416B) {
+			edge_serial->use_heartbeat = true;
+		}
+	}
+
+	INIT_DELAYED_WORK(&edge_serial->heartbeat_work, edge_heartbeat_work);
+	edge_heartbeat_schedule(edge_serial);
+
 	return 0;
 }
 
@@ -2402,7 +2519,10 @@ static void edge_disconnect(struct usb_serial *serial)
 
 static void edge_release(struct usb_serial *serial)
 {
-	kfree(usb_get_serial_data(serial));
+	struct edgeport_serial *edge_serial = usb_get_serial_data(serial);
+
+	cancel_delayed_work_sync(&edge_serial->heartbeat_work);
+	kfree(edge_serial);
 }
 
 static int edge_port_probe(struct usb_serial_port *port)
@@ -2506,6 +2626,25 @@ static int edge_remove_sysfs_attrs(struct usb_serial_port *port)
 	return 0;
 }
 
+#ifdef CONFIG_PM
+static int edge_suspend(struct usb_serial *serial, pm_message_t message)
+{
+	struct edgeport_serial *edge_serial = usb_get_serial_data(serial);
+
+	cancel_delayed_work_sync(&edge_serial->heartbeat_work);
+
+	return 0;
+}
+
+static int edge_resume(struct usb_serial *serial)
+{
+	struct edgeport_serial *edge_serial = usb_get_serial_data(serial);
+
+	edge_heartbeat_schedule(edge_serial);
+
+	return 0;
+}
+#endif
 
 static struct usb_serial_driver edgeport_1port_device = {
 	.driver = {
@@ -2538,6 +2677,10 @@ static struct usb_serial_driver edgeport_1port_device = {
 	.read_int_callback	= edge_interrupt_callback,
 	.read_bulk_callback	= edge_bulk_in_callback,
 	.write_bulk_callback	= edge_bulk_out_callback,
+#ifdef CONFIG_PM
+	.suspend		= edge_suspend,
+	.resume			= edge_resume,
+#endif
 };
 
 static struct usb_serial_driver edgeport_2port_device = {
@@ -2571,6 +2714,10 @@ static struct usb_serial_driver edgeport_2port_device = {
 	.read_int_callback	= edge_interrupt_callback,
 	.read_bulk_callback	= edge_bulk_in_callback,
 	.write_bulk_callback	= edge_bulk_out_callback,
+#ifdef CONFIG_PM
+	.suspend		= edge_suspend,
+	.resume			= edge_resume,
+#endif
 };
 
 static struct usb_serial_driver * const serial_drivers[] = {
diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index f5257af..ae682e4 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/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;
 }