[PATCH] USB: CP2101 Add support for flow control

Added support to get/set flow control line levels using TIOCMGET and
TIOCMSET.
Added support for RTSCTS hardware flow control.
cp2101_get_config and cp2101_set_config modified to support long request
strings, required for configuring flow control.

Signed-off-by: Craig Shelley craig@microtron.org.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 275 insertions, 88 deletions

diff --git a/drivers/usb/serial/cp2101.c b/drivers/usb/serial/cp2101.c
index 7e9bb63eb466..4ace9964fc6b 100644
--- a/drivers/usb/serial/cp2101.c
+++ b/drivers/usb/serial/cp2101.c
@@ -7,6 +7,14 @@
  *      modify it under the terms of the GNU General Public License version
  *      2 as published by the Free Software Foundation.
  *
+ * Support to set flow control line levels using TIOCMGET and TIOCMSET
+ * thanks to Karl Hiramoto karl@hiramoto.org. RTSCTS hardware flow
+ * control thanks to Munir Nassar nassarmu@real-time.com
+ *
+ * Outstanding Issues:
+ *  Buffers are not flushed when the port is opened.
+ *  Multiple calls to write() may fail with "Resource temporarily unavailable"
+ *
  */
 
 #include <linux/config.h>
@@ -24,7 +32,7 @@
 /*
  * Version Information
  */
-#define DRIVER_VERSION "v0.03"
+#define DRIVER_VERSION "v0.04"
 #define DRIVER_DESC "Silicon Labs CP2101/CP2102 RS232 serial adaptor driver"
 
 /*
@@ -35,6 +43,9 @@ static void cp2101_cleanup(struct usb_serial_port*);
 static void cp2101_close(struct usb_serial_port*, struct file*);
 static void cp2101_get_termios(struct usb_serial_port*);
 static void cp2101_set_termios(struct usb_serial_port*, struct termios*);
+static int cp2101_tiocmget (struct usb_serial_port *, struct file *);
+static int cp2101_tiocmset (struct usb_serial_port *, struct file *,
+                unsigned int, unsigned int);
 static void cp2101_break_ctl(struct usb_serial_port*, int);
 static int cp2101_startup (struct usb_serial *);
 static void cp2101_shutdown(struct usb_serial*);
@@ -43,9 +54,10 @@ static void cp2101_shutdown(struct usb_serial*);
 static int debug;
 
 static struct usb_device_id id_table [] = {
-        {USB_DEVICE(0x10c4, 0xea60) },  /*Silicon labs factory default*/
-        {USB_DEVICE(0x10ab, 0x10c5) },  /*Siemens MC60 Cable*/
-        { } /* Terminating Entry*/
+        { USB_DEVICE(0x10C4, 0xEA60) }, /* Silicon Labs factory default */
+        { USB_DEVICE(0x10C4, 0x80CA) }, /* Degree Controls Inc */
+        { USB_DEVICE(0x10AB, 0x10C5) }, /* Siemens MC60 Cable */
+        { } /* Terminating Entry */
 };
 
 MODULE_DEVICE_TABLE (usb, id_table);
@@ -70,32 +82,35 @@ static struct usb_serial_device_type cp2101_device = {
         .close                  = cp2101_close,
         .break_ctl              = cp2101_break_ctl,
         .set_termios            = cp2101_set_termios,
+        .tiocmget               = cp2101_tiocmget,
+        .tiocmset               = cp2101_tiocmset,
         .attach                 = cp2101_startup,
         .shutdown               = cp2101_shutdown,
 };
 
-/*Config request types*/
+/* Config request types */
 #define REQTYPE_HOST_TO_DEVICE  0x41
 #define REQTYPE_DEVICE_TO_HOST  0xc1
 
-/*Config SET requests. To GET, add 1 to the request number*/
-#define CP2101_UART             0x00    /*Enable / Disable*/
-#define CP2101_BAUDRATE         0x01    /*(BAUD_RATE_GEN_FREQ / baudrate)*/
-#define CP2101_BITS             0x03    /*0x(0)(data bits)(parity)(stop bits)*/
-#define CP2101_BREAK            0x05    /*On / Off*/
-#define CP2101_DTRRTS           0x07    /*101 / 202  ???*/
-#define CP2101_CONFIG_16        0x13    /*16 bytes of config data ???*/
-#define CP2101_CONFIG_6         0x19    /*6 bytes of config data ???*/
+/* Config SET requests. To GET, add 1 to the request number */
+#define CP2101_UART             0x00    /* Enable / Disable */
+#define CP2101_BAUDRATE         0x01    /* (BAUD_RATE_GEN_FREQ / baudrate) */
+#define CP2101_BITS             0x03    /* 0x(0)(databits)(parity)(stopbits) */
+#define CP2101_BREAK            0x05    /* On / Off */
+#define CP2101_CONTROL          0x07    /* Flow control line states */
+#define CP2101_MODEMCTL         0x13    /* Modem controls */
+#define CP2101_CONFIG_6         0x19    /* 6 bytes of config data ??? */
 
-/*CP2101_UART*/
+/* CP2101_UART */
 #define UART_ENABLE             0x0001
 #define UART_DISABLE            0x0000
 
-/*CP2101_BAUDRATE*/
+/* CP2101_BAUDRATE */
 #define BAUD_RATE_GEN_FREQ      0x384000
 
-/*CP2101_BITS*/
+/* CP2101_BITS */
 #define BITS_DATA_MASK          0X0f00
+#define BITS_DATA_5             0X0500
 #define BITS_DATA_6             0X0600
 #define BITS_DATA_7             0X0700
 #define BITS_DATA_8             0X0800
@@ -112,64 +127,137 @@ static struct usb_serial_device_type cp2101_device = {
 #define BITS_STOP_1             0x0000
 #define BITS_STOP_1_5           0x0001
 #define BITS_STOP_2             0x0002
+
+/* CP2101_BREAK */
 #define BREAK_ON                0x0000
 #define BREAK_OFF               0x0001
 
+/* CP2101_CONTROL */
+#define CONTROL_DTR             0x0001
+#define CONTROL_RTS             0x0002
+#define CONTROL_CTS             0x0010
+#define CONTROL_DSR             0x0020
+#define CONTROL_RING            0x0040
+#define CONTROL_DCD             0x0080
+#define CONTROL_WRITE_DTR       0x0100
+#define CONTROL_WRITE_RTS       0x0200
 
-static int cp2101_get_config(struct usb_serial_port* port, u8 request)
+/*
+ * cp2101_get_config
+ * Reads from the CP2101 configuration registers
+ * 'size' is specified in bytes.
+ * 'data' is a pointer to a pre-allocated array of integers large
+ * enough to hold 'size' bytes (with 4 bytes to each integer)
+ */
+static int cp2101_get_config(struct usb_serial_port* port, u8 request,
+                unsigned int *data, int size)
 {
         struct usb_serial *serial = port->serial;
-        unsigned char buf[4];
-        unsigned int value;
-        int result, i;
+        u32 *buf;
+        int result, i, length;
+
+        /* Number of integers required to contain the array */
+        length = (((size - 1) | 3) + 1)/4;
+
+        buf = kmalloc (length * sizeof(u32), GFP_KERNEL);
+        memset(buf, 0, length * sizeof(u32));
+
+        if (!buf) {
+                dev_err(&port->dev, "%s - out of memory.\n", __FUNCTION__);
+                return -ENOMEM;
+        }
 
-        /*For get requests, the request number must be incremented*/
+        /* For get requests, the request number must be incremented */
         request++;
 
-        /*Issue the request, attempting to read 4 bytes*/
+        /* Issue the request, attempting to read 'size' bytes */
         result = usb_control_msg (serial->dev,usb_rcvctrlpipe (serial->dev, 0),
                                 request, REQTYPE_DEVICE_TO_HOST, 0x0000,
-                                0, buf, 4, 300);
+                                0, buf, size, 300);
 
-        if (result < 0) {
-                dev_err(&port->dev, "%s - Unable to send config request, "
-                                "request=0x%x result=%d\n",
-                                __FUNCTION__, request, result);
-                return result;
-        }
+        /* Convert data into an array of integers */
+        for (i=0; i<length; i++)
+                data[i] = le32_to_cpu(buf[i]);
 
-        /*Assemble each byte read into an integer value*/
-        value = 0;
-        for (i=0; i<4 && i<result; i++)
-                value |= (buf[i] << (i * 8));
+        kfree(buf);
 
-        dbg( " %s - request=0x%x result=%d value=0x%x",
-                        __FUNCTION__, request, result, value);
+        if (result != size) {
+                dev_err(&port->dev, "%s - Unable to send config request, "
+                                "request=0x%x size=%d result=%d\n",
+                                __FUNCTION__, request, size, result);
+                return -EPROTO;
+        }
 
-        return value;
+        return 0;
 }
 
-static int cp2101_set_config(struct usb_serial_port* port, u8 request, u16 value)
+/*
+ * cp2101_set_config
+ * Writes to the CP2101 configuration registers
+ * Values less than 16 bits wide are sent directly
+ * 'size' is specified in bytes.
+ */
+static int cp2101_set_config(struct usb_serial_port* port, u8 request,
+                unsigned int *data, int size)
 {
         struct usb_serial *serial = port->serial;
-        int result;
-        result = usb_control_msg (serial->dev, usb_sndctrlpipe(serial->dev, 0),
-                        request, REQTYPE_HOST_TO_DEVICE, value,
-                        0, NULL, 0, 300);
+        u32 *buf;
+        int result, i, length;
 
-        if (result <0) {
-                dev_err(&port->dev, "%s - Unable to send config request, "
-                                "request=0x%x value=0x%x result=%d\n",
-                                __FUNCTION__, request, value, result);
-                return result;
+        /* Number of integers required to contain the array */
+        length = (((size - 1) | 3) + 1)/4;
+
+        buf = kmalloc(length * sizeof(u32), GFP_KERNEL);
+        if (!buf) {
+                dev_err(&port->dev, "%s - out of memory.\n",
+                                __FUNCTION__);
+                return -ENOMEM;
+        }
+
+        /* Array of integers into bytes */
+        for (i = 0; i < length; i++)
+                buf[i] = cpu_to_le32(data[i]);
+
+        if (size > 2) {
+                result = usb_control_msg (serial->dev,
+                                usb_sndctrlpipe(serial->dev, 0),
+                                request, REQTYPE_HOST_TO_DEVICE, 0x0000,
+                                0, buf, size, 300);
+        } else {
+                result = usb_control_msg (serial->dev,
+                                usb_sndctrlpipe(serial->dev, 0),
+                                request, REQTYPE_HOST_TO_DEVICE, data[0],
+                                0, NULL, 0, 300);
         }
 
-        dbg(" %s - request=0x%x value=0x%x result=%d",
-                        __FUNCTION__, request, value, result);
+        kfree(buf);
+
+        if ((size > 2 && result != size) || result < 0) {
+                dev_err(&port->dev, "%s - Unable to send request, "
+                                "request=0x%x size=%d result=%d\n",
+                                __FUNCTION__, request, size, result);
+                return -EPROTO;
+        }
 
+        /* Single data value */
+        result = usb_control_msg (serial->dev,
+                        usb_sndctrlpipe(serial->dev, 0),
+                        request, REQTYPE_HOST_TO_DEVICE, data[0],
+                        0, NULL, 0, 300);
         return 0;
 }
 
+/*
+ * cp2101_set_config_single
+ * Convenience function for calling cp2101_set_config on single data values
+ * without requiring an integer pointer
+ */
+static inline int cp2101_set_config_single(struct usb_serial_port* port,
+                u8 request, unsigned int data)
+{
+        return cp2101_set_config(port, request, &data, 2);
+}
+
 static int cp2101_open (struct usb_serial_port *port, struct file *filp)
 {
         struct usb_serial *serial = port->serial;
@@ -177,7 +265,7 @@ static int cp2101_open (struct usb_serial_port *port, struct file *filp)
 
         dbg("%s - port %d", __FUNCTION__, port->number);
 
-        if (cp2101_set_config(port, CP2101_UART, UART_ENABLE)) {
+        if (cp2101_set_config_single(port, CP2101_UART, UART_ENABLE)) {
                 dev_err(&port->dev, "%s - Unable to enable UART\n",
                                 __FUNCTION__);
                 return -EPROTO;
@@ -198,9 +286,12 @@ static int cp2101_open (struct usb_serial_port *port, struct file *filp)
                 return result;
         }
 
-        /*Configure the termios structure*/
+        /* Configure the termios structure */
         cp2101_get_termios(port);
 
+        /* Set the DTR and RTS pins low */
+        cp2101_tiocmset(port, NULL, TIOCM_DTR | TIOCM_RTS, 0);
+
         return 0;
 }
 
@@ -228,16 +319,18 @@ static void cp2101_close (struct usb_serial_port *port, struct file * filp)
         usb_kill_urb(port->write_urb);
         usb_kill_urb(port->read_urb);
 
-        cp2101_set_config(port, CP2101_UART, UART_DISABLE);
+        cp2101_set_config_single(port, CP2101_UART, UART_DISABLE);
 }
 
-/* cp2101_get_termios*/
-/* Reads the baud rate, data bits, parity and stop bits from the device*/
-/* Corrects any unsupported values*/
-/* Configures the termios structure to reflect the state of the device*/
+/*
+ * cp2101_get_termios
+ * Reads the baud rate, data bits, parity, stop bits and flow control mode
+ * from the device, corrects any unsupported values, and configures the
+ * termios structure to reflect the state of the device
+ */
 static void cp2101_get_termios (struct usb_serial_port *port)
 {
-        unsigned int cflag;
+        unsigned int cflag, modem_ctl[4];
         int baud;
         int bits;
 
@@ -249,15 +342,16 @@ static void cp2101_get_termios (struct usb_serial_port *port)
         }
         cflag = port->tty->termios->c_cflag;
 
-        baud = cp2101_get_config(port, CP2101_BAUDRATE);
-        /*Convert to baudrate*/
+        cp2101_get_config(port, CP2101_BAUDRATE, &baud, 2);
+        /* Convert to baudrate */
         if (baud)
                 baud = BAUD_RATE_GEN_FREQ / baud;
 
         dbg("%s - baud rate = %d", __FUNCTION__, baud);
         cflag &= ~CBAUD;
         switch (baud) {
-                /* The baud rates which are commented out below
+                /*
+                 * The baud rates which are commented out below
                  * appear to be supported by the device
                  * but are non-standard
                  */
@@ -284,14 +378,18 @@ static void cp2101_get_termios (struct usb_serial_port *port)
                         dbg("%s - Baud rate is not supported, "
                                         "using 9600 baud", __FUNCTION__);
                         cflag |= B9600;
-                        cp2101_set_config(port, CP2101_BAUDRATE,
+                        cp2101_set_config_single(port, CP2101_BAUDRATE,
                                         (BAUD_RATE_GEN_FREQ/9600));
                         break;
         }
 
-        bits = cp2101_get_config(port, CP2101_BITS);
+        cp2101_get_config(port, CP2101_BITS, &bits, 2);
         cflag &= ~CSIZE;
         switch(bits & BITS_DATA_MASK) {
+                case BITS_DATA_5:
+                        dbg("%s - data bits = 5", __FUNCTION__);
+                        cflag |= CS5;
+                        break;
                 case BITS_DATA_6:
                         dbg("%s - data bits = 6", __FUNCTION__);
                         cflag |= CS6;
@@ -310,7 +408,7 @@ static void cp2101_get_termios (struct usb_serial_port *port)
                         cflag |= CS8;
                         bits &= ~BITS_DATA_MASK;
                         bits |= BITS_DATA_8;
-                        cp2101_set_config(port, CP2101_BITS, bits);
+                        cp2101_set_config(port, CP2101_BITS, &bits, 2);
                         break;
                 default:
                         dbg("%s - Unknown number of data bits, "
@@ -318,7 +416,7 @@ static void cp2101_get_termios (struct usb_serial_port *port)
                         cflag |= CS8;
                         bits &= ~BITS_DATA_MASK;
                         bits |= BITS_DATA_8;
-                        cp2101_set_config(port, CP2101_BITS, bits);
+                        cp2101_set_config(port, CP2101_BITS, &bits, 2);
                         break;
         }
 
@@ -341,21 +439,21 @@ static void cp2101_get_termios (struct usb_serial_port *port)
                                         "disabling parity)", __FUNCTION__);
                         cflag &= ~PARENB;
                         bits &= ~BITS_PARITY_MASK;
-                        cp2101_set_config(port, CP2101_BITS, bits);
+                        cp2101_set_config(port, CP2101_BITS, &bits, 2);
                         break;
                 case BITS_PARITY_SPACE:
                         dbg("%s - parity = SPACE (not supported, "
                                         "disabling parity)", __FUNCTION__);
                         cflag &= ~PARENB;
                         bits &= ~BITS_PARITY_MASK;
-                        cp2101_set_config(port, CP2101_BITS, bits);
+                        cp2101_set_config(port, CP2101_BITS, &bits, 2);
                         break;
                 default:
                         dbg("%s - Unknown parity mode, "
                                         "disabling parity", __FUNCTION__);
                         cflag &= ~PARENB;
                         bits &= ~BITS_PARITY_MASK;
-                        cp2101_set_config(port, CP2101_BITS, bits);
+                        cp2101_set_config(port, CP2101_BITS, &bits, 2);
                         break;
         }
 
@@ -366,9 +464,9 @@ static void cp2101_get_termios (struct usb_serial_port *port)
                         break;
                 case BITS_STOP_1_5:
                         dbg("%s - stop bits = 1.5 (not supported, "
-                                        "using 1 stop bit", __FUNCTION__);
+                                        "using 1 stop bit)", __FUNCTION__);
                         bits &= ~BITS_STOP_MASK;
-                        cp2101_set_config(port, CP2101_BITS, bits);
+                        cp2101_set_config(port, CP2101_BITS, &bits, 2);
                         break;
                 case BITS_STOP_2:
                         dbg("%s - stop bits = 2", __FUNCTION__);
@@ -378,10 +476,19 @@ static void cp2101_get_termios (struct usb_serial_port *port)
                         dbg("%s - Unknown number of stop bits, "
                                         "using 1 stop bit", __FUNCTION__);
                         bits &= ~BITS_STOP_MASK;
-                        cp2101_set_config(port, CP2101_BITS, bits);
+                        cp2101_set_config(port, CP2101_BITS, &bits, 2);
                         break;
         }
 
+        cp2101_get_config(port, CP2101_MODEMCTL, modem_ctl, 16);
+        if (modem_ctl[0] & 0x0008) {
+                dbg("%s - flow control = CRTSCTS", __FUNCTION__);
+                cflag |= CRTSCTS;
+        } else {
+                dbg("%s - flow control = NONE", __FUNCTION__);
+                cflag &= ~CRTSCTS;
+        }
+
         port->tty->termios->c_cflag = cflag;
 }
 
@@ -389,8 +496,8 @@ static void cp2101_set_termios (struct usb_serial_port *port,
                 struct termios *old_termios)
 {
         unsigned int cflag, old_cflag=0;
-        int baud=0;
-        int bits;
+        int baud=0, bits;
+        unsigned int modem_ctl[4];
 
         dbg("%s - port %d", __FUNCTION__, port->number);
 
@@ -400,7 +507,7 @@ static void cp2101_set_termios (struct usb_serial_port *port,
         }
         cflag = port->tty->termios->c_cflag;
 
-        /* check that they really want us to change something */
+        /* Check that they really want us to change something */
         if (old_termios) {
                 if ((cflag == old_termios->c_cflag) &&
                                 (RELEVANT_IFLAG(port->tty->termios->c_iflag)
@@ -415,7 +522,8 @@ static void cp2101_set_termios (struct usb_serial_port *port,
         /* If the baud rate is to be updated*/
         if ((cflag & CBAUD) != (old_cflag & CBAUD)) {
                 switch (cflag & CBAUD) {
-                        /* The baud rates which are commented out below
+                        /*
+                         * The baud rates which are commented out below
                          * appear to be supported by the device
                          * but are non-standard
                          */
@@ -448,18 +556,22 @@ static void cp2101_set_termios (struct usb_serial_port *port,
                 if (baud) {
                         dbg("%s - Setting baud rate to %d baud", __FUNCTION__,
                                         baud);
-                        if (cp2101_set_config(port, CP2101_BAUDRATE,
+                        if (cp2101_set_config_single(port, CP2101_BAUDRATE,
                                                 (BAUD_RATE_GEN_FREQ / baud)))
                                 dev_err(&port->dev, "Baud rate requested not "
                                                 "supported by device\n");
                 }
         }
 
-        /*If the number of data bits is to be updated*/
+        /* If the number of data bits is to be updated */
         if ((cflag & CSIZE) != (old_cflag & CSIZE)) {
-                bits = cp2101_get_config(port, CP2101_BITS);
+                cp2101_get_config(port, CP2101_BITS, &bits, 2);
                 bits &= ~BITS_DATA_MASK;
                 switch (cflag & CSIZE) {
+                        case CS5:
+                                bits |= BITS_DATA_5;
+                                dbg("%s - data bits = 5", __FUNCTION__);
+                                break;
                         case CS6:
                                 bits |= BITS_DATA_6;
                                 dbg("%s - data bits = 6", __FUNCTION__);
@@ -483,13 +595,13 @@ static void cp2101_set_termios (struct usb_serial_port *port,
                                 bits |= BITS_DATA_8;
                                 break;
                 }
-                if (cp2101_set_config(port, CP2101_BITS, bits))
+                if (cp2101_set_config(port, CP2101_BITS, &bits, 2))
                         dev_err(&port->dev, "Number of data bits requested "
                                         "not supported by device\n");
         }
 
         if ((cflag & (PARENB|PARODD)) != (old_cflag & (PARENB|PARODD))) {
-                bits = cp2101_get_config(port, CP2101_BITS);
+                cp2101_get_config(port, CP2101_BITS, &bits, 2);
                 bits &= ~BITS_PARITY_MASK;
                 if (cflag & PARENB) {
                         if (cflag & PARODD) {
@@ -500,13 +612,13 @@ static void cp2101_set_termios (struct usb_serial_port *port,
                                 dbg("%s - parity = EVEN", __FUNCTION__);
                         }
                 }
-                if (cp2101_set_config(port, CP2101_BITS, bits))
+                if (cp2101_set_config(port, CP2101_BITS, &bits, 2))
                         dev_err(&port->dev, "Parity mode not supported "
                                         "by device\n");
         }
 
         if ((cflag & CSTOPB) != (old_cflag & CSTOPB)) {
-                bits = cp2101_get_config(port, CP2101_BITS);
+                cp2101_get_config(port, CP2101_BITS, &bits, 2);
                 bits &= ~BITS_STOP_MASK;
                 if (cflag & CSTOPB) {
                         bits |= BITS_STOP_2;
@@ -515,15 +627,90 @@ static void cp2101_set_termios (struct usb_serial_port *port,
                         bits |= BITS_STOP_1;
                         dbg("%s - stop bits = 1", __FUNCTION__);
                 }
-                if (cp2101_set_config(port, CP2101_BITS, bits))
+                if (cp2101_set_config(port, CP2101_BITS, &bits, 2))
                         dev_err(&port->dev, "Number of stop bits requested "
                                         "not supported by device\n");
         }
+
+        if ((cflag & CRTSCTS) != (old_cflag & CRTSCTS)) {
+                cp2101_get_config(port, CP2101_MODEMCTL, modem_ctl, 16);
+                dbg("%s - read modem controls = 0x%.4x 0x%.4x 0x%.4x 0x%.4x",
+                                __FUNCTION__, modem_ctl[0], modem_ctl[1],
+                                modem_ctl[2], modem_ctl[3]);
+
+                if (cflag & CRTSCTS) {
+                        modem_ctl[0] &= ~0x7B;
+                        modem_ctl[0] |= 0x09;
+                        modem_ctl[1] = 0x80;
+                        dbg("%s - flow control = CRTSCTS", __FUNCTION__);
+                } else {
+                        modem_ctl[0] &= ~0x7B;
+                        modem_ctl[0] |= 0x01;
+                        modem_ctl[1] |= 0x40;
+                        dbg("%s - flow control = NONE", __FUNCTION__);
+                }
+
+                dbg("%s - write modem controls = 0x%.4x 0x%.4x 0x%.4x 0x%.4x",
+                                __FUNCTION__, modem_ctl[0], modem_ctl[1],
+                                modem_ctl[2], modem_ctl[3]);
+                cp2101_set_config(port, CP2101_MODEMCTL, modem_ctl, 16);
+        }
+
+}
+
+static int cp2101_tiocmset (struct usb_serial_port *port, struct file *file,
+                unsigned int set, unsigned int clear)
+{
+        int control = 0;
+
+        dbg("%s - port %d", __FUNCTION__, port->number);
+
+        if (set & TIOCM_RTS) {
+                control |= CONTROL_RTS;
+                control |= CONTROL_WRITE_RTS;
+        }
+        if (set & TIOCM_DTR) {
+                control |= CONTROL_DTR;
+                control |= CONTROL_WRITE_DTR;
+        }
+        if (clear & TIOCM_RTS) {
+                control &= ~CONTROL_RTS;
+                control |= CONTROL_WRITE_RTS;
+        }
+        if (clear & TIOCM_DTR) {
+                control &= ~CONTROL_DTR;
+                control |= CONTROL_WRITE_DTR;
+        }
+
+        dbg("%s - control = 0x%.4x", __FUNCTION__, control);
+
+        return cp2101_set_config(port, CP2101_CONTROL, &control, 2);
+
+}
+
+static int cp2101_tiocmget (struct usb_serial_port *port, struct file *file)
+{
+        int control, result;
+
+        dbg("%s - port %d", __FUNCTION__, port->number);
+
+        cp2101_get_config(port, CP2101_CONTROL, &control, 1);
+
+        result = ((control & CONTROL_DTR) ? TIOCM_DTR : 0)
+                |((control & CONTROL_RTS) ? TIOCM_RTS : 0)
+                |((control & CONTROL_CTS) ? TIOCM_CTS : 0)
+                |((control & CONTROL_DSR) ? TIOCM_DSR : 0)
+                |((control & CONTROL_RING)? TIOCM_RI  : 0)
+                |((control & CONTROL_DCD) ? TIOCM_CD  : 0);
+
+        dbg("%s - control = 0x%.2x", __FUNCTION__, control);
+
+        return result;
 }
 
 static void cp2101_break_ctl (struct usb_serial_port *port, int break_state)
 {
-        u16 state;
+        int state;
 
         dbg("%s - port %d", __FUNCTION__, port->number);
         if (break_state == 0)
@@ -532,12 +719,12 @@ static void cp2101_break_ctl (struct usb_serial_port *port, int break_state)
                 state = BREAK_ON;
         dbg("%s - turning break %s", __FUNCTION__,
                         state==BREAK_OFF ? "off" : "on");
-        cp2101_set_config(port, CP2101_BREAK, state);
+        cp2101_set_config(port, CP2101_BREAK, &state, 2);
 }
 
 static int cp2101_startup (struct usb_serial *serial)
 {
-        /*CP2101 buffers behave strangely unless device is reset*/
+        /* CP2101 buffers behave strangely unless device is reset */
         usb_reset_device(serial->dev);
         return 0;
 }
@@ -548,7 +735,7 @@ static void cp2101_shutdown (struct usb_serial *serial)
 
         dbg("%s", __FUNCTION__);
 
-        /* stop reads and writes on all ports */
+        /* Stop reads and writes on all ports */
         for (i=0; i < serial->num_ports; ++i) {
                 cp2101_cleanup(serial->port[i]);
         }
@@ -560,16 +747,16 @@ static int __init cp2101_init (void)
 
         retval = usb_serial_register(&cp2101_device);
         if (retval)
-                return retval; /*Failed to register*/
+                return retval; /* Failed to register */
 
         retval = usb_register(&cp2101_driver);
         if (retval) {
-                /*Failed to register*/
+                /* Failed to register */
                 usb_serial_deregister(&cp2101_device);
                 return retval;
         }
 
-        /*Success*/
+        /* Success */
         info(DRIVER_DESC " " DRIVER_VERSION);
         return 0;
 }