/*
 * Silicon Laboratories CP210x USB to RS232 serial adaptor driver
 *
 * Copyright (C) 2005 Craig Shelley (craig@microtron.org.uk)
 *
 *      This program is free software; you can redistribute it and/or
 *      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
 *
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/usb.h>
#include <linux/uaccess.h>
#include <linux/usb/serial.h>

/*
 * Version Information
 */
#define DRIVER_VERSION "v0.09"
#define DRIVER_DESC "Silicon Labs CP210x RS232 serial adaptor driver"

/*
 * Function Prototypes
 */
static int cp210x_open(struct tty_struct *tty, struct usb_serial_port *);
static void cp210x_cleanup(struct usb_serial_port *);
static void cp210x_close(struct usb_serial_port *);
static void cp210x_get_termios(struct tty_struct *,
        struct usb_serial_port *port);
static void cp210x_get_termios_port(struct usb_serial_port *port,
        unsigned int *cflagp, unsigned int *baudp);
static void cp210x_set_termios(struct tty_struct *, struct usb_serial_port *,
                                                        struct ktermios*);
static int cp210x_tiocmget(struct tty_struct *, struct file *);
static int cp210x_tiocmset(struct tty_struct *, struct file *,
                unsigned int, unsigned int);
static int cp210x_tiocmset_port(struct usb_serial_port *port, struct file *,
                unsigned int, unsigned int);
static void cp210x_break_ctl(struct tty_struct *, int);
static int cp210x_startup(struct usb_serial *);
static void cp210x_disconnect(struct usb_serial *);
static void cp210x_dtr_rts(struct usb_serial_port *p, int on);
static int cp210x_carrier_raised(struct usb_serial_port *p);

static int debug;

static struct usb_device_id id_table [] = {
        { USB_DEVICE(0x0471, 0x066A) }, /* AKTAKOM ACE-1001 cable */
        { USB_DEVICE(0x0489, 0xE000) }, /* Pirelli Broadband S.p.A, DP-L10 SIP/GSM Mobile */
        { USB_DEVICE(0x0745, 0x1000) }, /* CipherLab USB CCD Barcode Scanner 1000 */
        { USB_DEVICE(0x08e6, 0x5501) }, /* Gemalto Prox-PU/CU contactless smartcard reader */
        { USB_DEVICE(0x08FD, 0x000A) }, /* Digianswer A/S , ZigBee/802.15.4 MAC Device */
        { USB_DEVICE(0x0FCF, 0x1003) }, /* Dynastream ANT development board */
        { USB_DEVICE(0x0FCF, 0x1004) }, /* Dynastream ANT2USB */
        { USB_DEVICE(0x0FCF, 0x1006) }, /* Dynastream ANT development board */
        { USB_DEVICE(0x10A6, 0xAA26) }, /* Knock-off DCU-11 cable */
        { USB_DEVICE(0x10AB, 0x10C5) }, /* Siemens MC60 Cable */
        { USB_DEVICE(0x10B5, 0xAC70) }, /* Nokia CA-42 USB */
        { USB_DEVICE(0x10C4, 0x0F91) }, /* Vstabi */
        { USB_DEVICE(0x10C4, 0x1101) }, /* Arkham Technology DS101 Bus Monitor */
        { USB_DEVICE(0x10C4, 0x1601) }, /* Arkham Technology DS101 Adapter */
        { USB_DEVICE(0x10C4, 0x800A) }, /* SPORTident BSM7-D-USB main station */
        { USB_DEVICE(0x10C4, 0x803B) }, /* Pololu USB-serial converter */
        { USB_DEVICE(0x10C4, 0x8053) }, /* Enfora EDG1228 */
        { USB_DEVICE(0x10C4, 0x8054) }, /* Enfora GSM2228 */
        { USB_DEVICE(0x10C4, 0x8066) }, /* Argussoft In-System Programmer */
        { USB_DEVICE(0x10C4, 0x807A) }, /* Crumb128 board */
        { USB_DEVICE(0x10C4, 0x80CA) }, /* Degree Controls Inc */
        { USB_DEVICE(0x10C4, 0x80DD) }, /* Tracient RFID */
        { USB_DEVICE(0x10C4, 0x80F6) }, /* Suunto sports instrument */
        { USB_DEVICE(0x10C4, 0x8115) }, /* Arygon NFC/Mifare Reader */
        { USB_DEVICE(0x10C4, 0x813D) }, /* Burnside Telecom Deskmobile */
        { USB_DEVICE(0x10C4, 0x813F) }, /* Tams Master Easy Control */
        { USB_DEVICE(0x10C4, 0x814A) }, /* West Mountain Radio RIGblaster P&P */
        { USB_DEVICE(0x10C4, 0x814B) }, /* West Mountain Radio RIGtalk */
        { USB_DEVICE(0x10C4, 0x815E) }, /* Helicomm IP-Link 1220-DVM */
        { USB_DEVICE(0x10C4, 0x819F) }, /* MJS USB Toslink Switcher */
        { USB_DEVICE(0x10C4, 0x81A6) }, /* ThinkOptics WavIt */
        { USB_DEVICE(0x10C4, 0x81AC) }, /* MSD Dash Hawk */
        { USB_DEVICE(0x10C4, 0x81C8) }, /* Lipowsky Industrie Elektronik GmbH, Baby-JTAG */
        { USB_DEVICE(0x10C4, 0x81E2) }, /* Lipowsky Industrie Elektronik GmbH, Baby-LIN */
        { USB_DEVICE(0x10C4, 0x81E7) }, /* Aerocomm Radio */
        { USB_DEVICE(0x10C4, 0x81F2) }, /* C1007 HF band RFID controller */
        { USB_DEVICE(0x10C4, 0x8218) }, /* Lipowsky Industrie Elektronik GmbH, HARP-1 */
        { USB_DEVICE(0x10C4, 0x822B) }, /* Modem EDGE(GSM) Comander 2 */
        { USB_DEVICE(0x10C4, 0x826B) }, /* Cygnal Integrated Products, Inc., Fasttrax GPS demostration module */
        { USB_DEVICE(0x10c4, 0x8293) }, /* Telegesys ETRX2USB */
        { USB_DEVICE(0x10C4, 0x82F9) }, /* Procyon AVS */
        { USB_DEVICE(0x10C4, 0x8341) }, /* Siemens MC35PU GPRS Modem */
        { USB_DEVICE(0x10C4, 0x8382) }, /* Cygnal Integrated Products, Inc. */
        { USB_DEVICE(0x10C4, 0x83A8) }, /* Amber Wireless AMB2560 */
        { USB_DEVICE(0x10C4, 0x8411) }, /* Kyocera GPS Module */
        { USB_DEVICE(0x10C4, 0x846E) }, /* BEI USB Sensor Interface (VCP) */
        { USB_DEVICE(0x10C4, 0xEA60) }, /* Silicon Labs factory default */
        { USB_DEVICE(0x10C4, 0xEA61) }, /* Silicon Labs factory default */
        { USB_DEVICE(0x10C4, 0xF001) }, /* Elan Digital Systems USBscope50 */
        { USB_DEVICE(0x10C4, 0xF002) }, /* Elan Digital Systems USBwave12 */
        { USB_DEVICE(0x10C4, 0xF003) }, /* Elan Digital Systems USBpulse100 */
        { USB_DEVICE(0x10C4, 0xF004) }, /* Elan Digital Systems USBcount50 */
        { USB_DEVICE(0x10C5, 0xEA61) }, /* Silicon Labs MobiData GPRS USB Modem */
        { USB_DEVICE(0x10CE, 0xEA6A) }, /* Silicon Labs MobiData GPRS USB Modem 100EU */
        { USB_DEVICE(0x13AD, 0x9999) }, /* Baltech card reader */
        { USB_DEVICE(0x1555, 0x0004) }, /* Owen AC4 USB-RS485 Converter */
        { USB_DEVICE(0x166A, 0x0303) }, /* Clipsal 5500PCU C-Bus USB interface */
        { USB_DEVICE(0x16D6, 0x0001) }, /* Jablotron serial interface */
        { USB_DEVICE(0x18EF, 0xE00F) }, /* ELV USB-I2C-Interface */
        { USB_DEVICE(0x413C, 0x9500) }, /* DW700 GPS USB interface */
        { } /* Terminating Entry */
};

MODULE_DEVICE_TABLE(usb, id_table);

static struct usb_driver cp210x_driver = {
        .name           = "cp210x",
        .probe          = usb_serial_probe,
        .disconnect     = usb_serial_disconnect,
        .id_table       = id_table,
        .no_dynamic_id  =       1,
};

static struct usb_serial_driver cp210x_device = {
        .driver = {
                .owner =        THIS_MODULE,
                .name =         "cp210x",
        },
        .usb_driver             = &cp210x_driver,
        .id_table               = id_table,
        .num_ports              = 1,
        .open                   = cp210x_open,
        .close                  = cp210x_close,
        .break_ctl              = cp210x_break_ctl,
        .set_termios            = cp210x_set_termios,
        .tiocmget               = cp210x_tiocmget,
        .tiocmset               = cp210x_tiocmset,
        .attach                 = cp210x_startup,
        .disconnect             = cp210x_disconnect,
        .dtr_rts                = cp210x_dtr_rts,
        .carrier_raised         = cp210x_carrier_raised
};

/* Config request types */
#define REQTYPE_HOST_TO_DEVICE  0x41
#define REQTYPE_DEVICE_TO_HOST  0xc1

/* Config request codes */
#define CP210X_IFC_ENABLE       0x00
#define CP210X_SET_BAUDDIV      0x01
#define CP210X_GET_BAUDDIV      0x02
#define CP210X_SET_LINE_CTL     0x03
#define CP210X_GET_LINE_CTL     0x04
#define CP210X_SET_BREAK        0x05
#define CP210X_IMM_CHAR         0x06
#define CP210X_SET_MHS          0x07
#define CP210X_GET_MDMSTS       0x08
#define CP210X_SET_XON          0x09
#define CP210X_SET_XOFF         0x0A
#define CP210X_SET_EVENTMASK    0x0B
#define CP210X_GET_EVENTMASK    0x0C
#define CP210X_SET_CHAR         0x0D
#define CP210X_GET_CHARS        0x0E
#define CP210X_GET_PROPS        0x0F
#define CP210X_GET_COMM_STATUS  0x10
#define CP210X_RESET            0x11
#define CP210X_PURGE            0x12
#define CP210X_SET_FLOW         0x13
#define CP210X_GET_FLOW         0x14
#define CP210X_EMBED_EVENTS     0x15
#define CP210X_GET_EVENTSTATE   0x16
#define CP210X_SET_CHARS        0x19

/* CP210X_IFC_ENABLE */
#define UART_ENABLE             0x0001
#define UART_DISABLE            0x0000

/* CP210X_(SET|GET)_BAUDDIV */
#define BAUD_RATE_GEN_FREQ      0x384000

/* CP210X_(SET|GET)_LINE_CTL */
#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
#define BITS_DATA_9             0X0900

#define BITS_PARITY_MASK        0x00f0
#define BITS_PARITY_NONE        0x0000
#define BITS_PARITY_ODD         0x0010
#define BITS_PARITY_EVEN        0x0020
#define BITS_PARITY_MARK        0x0030
#define BITS_PARITY_SPACE       0x0040

#define BITS_STOP_MASK          0x000f
#define BITS_STOP_1             0x0000
#define BITS_STOP_1_5           0x0001
#define BITS_STOP_2             0x0002

/* CP210X_SET_BREAK */
#define BREAK_ON                0x0000
#define BREAK_OFF               0x0001

/* CP210X_(SET_MHS|GET_MDMSTS) */
#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

/*
 * cp210x_get_config
 * Reads from the CP210x 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 cp210x_get_config(struct usb_serial_port *port, u8 request,
                unsigned int *data, int size)
{
        struct usb_serial *serial = port->serial;
        __le32 *buf;
        int result, i, length;

        /* Number of integers required to contain the array */
        length = (((size - 1) | 3) + 1)/4;

        buf = kcalloc(length, sizeof(__le32), GFP_KERNEL);
        if (!buf) {
                dev_err(&port->dev, "%s - out of memory.\n", __func__);
                return -ENOMEM;
        }

        /* 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, size, 300);

        /* Convert data into an array of integers */
        for (i = 0; i < length; i++)
                data[i] = le32_to_cpu(buf[i]);

        kfree(buf);

        if (result != size) {
                dbg("%s - Unable to send config request, "
                                "request=0x%x size=%d result=%d\n",
                                __func__, request, size, result);
                return -EPROTO;
        }

        return 0;
}

/*
 * cp210x_set_config
 * Writes to the CP210x configuration registers
 * Values less than 16 bits wide are sent directly
 * 'size' is specified in bytes.
 */
static int cp210x_set_config(struct usb_serial_port *port, u8 request,
                unsigned int *data, int size)
{
        struct usb_serial *serial = port->serial;
        __le32 *buf;
        int result, i, length;

        /* Number of integers required to contain the array */
        length = (((size - 1) | 3) + 1)/4;

        buf = kmalloc(length * sizeof(__le32), GFP_KERNEL);
        if (!buf) {
                dev_err(&port->dev, "%s - out of memory.\n",
                                __func__);
                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);
        }

        kfree(buf);

        if ((size > 2 && result != size) || result < 0) {
                dbg("%s - Unable to send request, "
                                "request=0x%x size=%d result=%d\n",
                                __func__, 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;
}

/*
 * cp210x_set_config_single
 * Convenience function for calling cp210x_set_config on single data values
 * without requiring an integer pointer
 */
static inline int cp210x_set_config_single(struct usb_serial_port *port,
                u8 request, unsigned int data)
{
        return cp210x_set_config(port, request, &data, 2);
}

/*
 * cp210x_quantise_baudrate
 * Quantises the baud rate as per AN205 Table 1
 */
static unsigned int cp210x_quantise_baudrate(unsigned int baud) {
        if      (baud <= 56)       baud = 0;
        else if (baud <= 300)      baud = 300;
        else if (baud <= 600)      baud = 600;
        else if (baud <= 1200)     baud = 1200;
        else if (baud <= 1800)     baud = 1800;
        else if (baud <= 2400)     baud = 2400;
        else if (baud <= 4000)     baud = 4000;
        else if (baud <= 4803)     baud = 4800;
        else if (baud <= 7207)     baud = 7200;
        else if (baud <= 9612)     baud = 9600;
        else if (baud <= 14428)    baud = 14400;
        else if (baud <= 16062)    baud = 16000;
        else if (baud <= 19250)    baud = 19200;
        else if (baud <= 28912)    baud = 28800;
        else if (baud <= 38601)    baud = 38400;
        else if (baud <= 51558)    baud = 51200;
        else if (baud <= 56280)    baud = 56000;
        else if (baud <= 58053)    baud = 57600;
        else if (baud <= 64111)    baud = 64000;
        else if (baud <= 77608)    baud = 76800;
        else if (baud <= 117028)   baud = 115200;
        else if (baud <= 129347)   baud = 128000;
        else if (baud <= 156868)   baud = 153600;
        else if (baud <= 237832)   baud = 230400;
        else if (baud <= 254234)   baud = 250000;
        else if (baud <= 273066)   baud = 256000;
        else if (baud <= 491520)   baud = 460800;
        else if (baud <= 567138)   baud = 500000;
        else if (baud <= 670254)   baud = 576000;
        else if (baud <= 1053257)  baud = 921600;
        else if (baud <= 1474560)  baud = 1228800;
        else if (baud <= 2457600)  baud = 1843200;
        else                       baud = 3686400;
        return baud;
}

static int cp210x_open(struct tty_struct *tty, struct usb_serial_port *port)
{
        struct usb_serial *serial = port->serial;
        int result;

        dbg("%s - port %d", __func__, port->number);

        if (cp210x_set_config_single(port, CP210X_IFC_ENABLE, UART_ENABLE)) {
                dev_err(&port->dev, "%s - Unable to enable UART\n",
                                __func__);
                return -EPROTO;
        }

        /* Start reading from the device */
        usb_fill_bulk_urb(port->read_urb, serial->dev,
                        usb_rcvbulkpipe(serial->dev,
                        port->bulk_in_endpointAddress),
                        port->read_urb->transfer_buffer,
                        port->read_urb->transfer_buffer_length,
                        serial->type->read_bulk_callback,
                        port);
        result = usb_submit_urb(port->read_urb, GFP_KERNEL);
        if (result) {
                dev_err(&port->dev, "%s - failed resubmitting read urb, "
                                "error %d\n", __func__, result);
                return result;
        }

        /* Configure the termios structure */
        cp210x_get_termios(tty, port);
        return 0;
}

static void cp210x_cleanup(struct usb_serial_port *port)
{
        struct usb_serial *serial = port->serial;

        dbg("%s - port %d", __func__, port->number);

        if (serial->dev) {
                /* shutdown any bulk reads that might be going on */
                if (serial->num_bulk_out)
                        usb_kill_urb(port->write_urb);
                if (serial->num_bulk_in)
                        usb_kill_urb(port->read_urb);
        }
}

static void cp210x_close(struct usb_serial_port *port)
{
        dbg("%s - port %d", __func__, port->number);

        /* shutdown our urbs */
        dbg("%s - shutting down urbs", __func__);
        usb_kill_urb(port->write_urb);
        usb_kill_urb(port->read_urb);

        mutex_lock(&port->serial->disc_mutex);
        if (!port->serial->disconnected)
                cp210x_set_config_single(port, CP210X_IFC_ENABLE, UART_DISABLE);
        mutex_unlock(&port->serial->disc_mutex);
}

/*
 * cp210x_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 cp210x_get_termios(struct tty_struct *tty,
        struct usb_serial_port *port)
{
        unsigned int baud;

        if (tty) {
                cp210x_get_termios_port(tty->driver_data,
                        &tty->termios->c_cflag, &baud);
                tty_encode_baud_rate(tty, baud, baud);
        }

        else {
                unsigned int cflag;
                cflag = 0;
                cp210x_get_termios_port(port, &cflag, &baud);
        }
}

/*
 * cp210x_get_termios_port
 * This is the heart of cp210x_get_termios which always uses a &usb_serial_port.
 */
static void cp210x_get_termios_port(struct usb_serial_port *port,
        unsigned int *cflagp, unsigned int *baudp)
{
        unsigned int cflag, modem_ctl[4];
        unsigned int baud;
        unsigned int bits;

        dbg("%s - port %d", __func__, port->number);

        cp210x_get_config(port, CP210X_GET_BAUDDIV, &baud, 2);
        /* Convert to baudrate */
        if (baud)
                baud = cp210x_quantise_baudrate((BAUD_RATE_GEN_FREQ + baud/2)/ baud);

        dbg("%s - baud rate = %d", __func__, baud);
        *baudp = baud;

        cflag = *cflagp;

        cp210x_get_config(port, CP210X_GET_LINE_CTL, &bits, 2);
        cflag &= ~CSIZE;
        switch (bits & BITS_DATA_MASK) {
        case BITS_DATA_5:
                dbg("%s - data bits = 5", __func__);
                cflag |= CS5;
                break;
        case BITS_DATA_6:
                dbg("%s - data bits = 6", __func__);
                cflag |= CS6;
                break;
        case BITS_DATA_7:
                dbg("%s - data bits = 7", __func__);
                cflag |= CS7;
                break;
        case BITS_DATA_8:
                dbg("%s - data bits = 8", __func__);
                cflag |= CS8;
                break;
        case BITS_DATA_9:
                dbg("%s - data bits = 9 (not supported, using 8 data bits)",
                                                                __func__);
                cflag |= CS8;
                bits &= ~BITS_DATA_MASK;
                bits |= BITS_DATA_8;
                cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
                break;
        default:
                dbg("%s - Unknown number of data bits, using 8", __func__);
                cflag |= CS8;
                bits &= ~BITS_DATA_MASK;
                bits |= BITS_DATA_8;
                cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
                break;
        }

        switch (bits & BITS_PARITY_MASK) {
        case BITS_PARITY_NONE:
                dbg("%s - parity = NONE", __func__);
                cflag &= ~PARENB;
                break;
        case BITS_PARITY_ODD:
                dbg("%s - parity = ODD", __func__);
                cflag |= (PARENB|PARODD);
                break;
        case BITS_PARITY_EVEN:
                dbg("%s - parity = EVEN", __func__);
                cflag &= ~PARODD;
                cflag |= PARENB;
                break;
        case BITS_PARITY_MARK:
                dbg("%s - parity = MARK (not supported, disabling parity)",
                                __func__);
                cflag &= ~PARENB;
                bits &= ~BITS_PARITY_MASK;
                cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
                break;
        case BITS_PARITY_SPACE:
                dbg("%s - parity = SPACE (not supported, disabling parity)",
                                __func__);
                cflag &= ~PARENB;
                bits &= ~BITS_PARITY_MASK;
                cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
                break;
        default:
                dbg("%s - Unknown parity mode, disabling parity", __func__);
                cflag &= ~PARENB;
                bits &= ~BITS_PARITY_MASK;
                cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
                break;
        }

        cflag &= ~CSTOPB;
        switch (bits & BITS_STOP_MASK) {
        case BITS_STOP_1:
                dbg("%s - stop bits = 1", __func__);
                break;
        case BITS_STOP_1_5:
                dbg("%s - stop bits = 1.5 (not supported, using 1 stop bit)",
                                                                __func__);
                bits &= ~BITS_STOP_MASK;
                cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
                break;
        case BITS_STOP_2:
                dbg("%s - stop bits = 2", __func__);
                cflag |= CSTOPB;
                break;
        default:
                dbg("%s - Unknown number of stop bits, using 1 stop bit",
                                                                __func__);
                bits &= ~BITS_STOP_MASK;
                cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
                break;
        }

        cp210x_get_config(port, CP210X_GET_FLOW, modem_ctl, 16);
        if (modem_ctl[0] & 0x0008) {
                dbg("%s - flow control = CRTSCTS", __func__);
                cflag |= CRTSCTS;
        } else {
                dbg("%s - flow control = NONE", __func__);
                cflag &= ~CRTSCTS;
        }

        *cflagp = cflag;
}

static void cp210x_set_termios(struct tty_struct *tty,
                struct usb_serial_port *port, struct ktermios *old_termios)
{
        unsigned int cflag, old_cflag;
        unsigned int baud = 0, bits;
        unsigned int modem_ctl[4];

        dbg("%s - port %d", __func__, port->number);

        if (!tty)
                return;

        tty->termios->c_cflag &= ~CMSPAR;
        cflag = tty->termios->c_cflag;
        old_cflag = old_termios->c_cflag;
        baud = cp210x_quantise_baudrate(tty_get_baud_rate(tty));

        /* If the baud rate is to be updated*/
        if (baud != tty_termios_baud_rate(old_termios) && baud != 0) {
                dbg("%s - Setting baud rate to %d baud", __func__,
                                baud);
                if (cp210x_set_config_single(port, CP210X_SET_BAUDDIV,
                                        ((BAUD_RATE_GEN_FREQ + baud/2) / baud))) {
                        dbg("Baud rate requested not supported by device\n");
                        baud = tty_termios_baud_rate(old_termios);
                }
        }
        /* Report back the resulting baud rate */
        tty_encode_baud_rate(tty, baud, baud);

        /* If the number of data bits is to be updated */
        if ((cflag & CSIZE) != (old_cflag & CSIZE)) {
                cp210x_get_config(port, CP210X_GET_LINE_CTL, &bits, 2);
                bits &= ~BITS_DATA_MASK;
                switch (cflag & CSIZE) {
                case CS5:
                        bits |= BITS_DATA_5;
                        dbg("%s - data bits = 5", __func__);
                        break;
                case CS6:
                        bits |= BITS_DATA_6;
                        dbg("%s - data bits = 6", __func__);
                        break;
                case CS7:
                        bits |= BITS_DATA_7;
                        dbg("%s - data bits = 7", __func__);
                        break;
                case CS8:
                        bits |= BITS_DATA_8;
                        dbg("%s - data bits = 8", __func__);
                        break;
                /*case CS9:
                        bits |= BITS_DATA_9;
                        dbg("%s - data bits = 9", __func__);
                        break;*/
                default:
                        dbg("cp210x driver does not "
                                        "support the number of bits requested,"
                                        " using 8 bit mode\n");
                                bits |= BITS_DATA_8;
                                break;
                }
                if (cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2))
                        dbg("Number of data bits requested "
                                        "not supported by device\n");
        }

        if ((cflag & (PARENB|PARODD)) != (old_cflag & (PARENB|PARODD))) {
                cp210x_get_config(port, CP210X_GET_LINE_CTL, &bits, 2);
                bits &= ~BITS_PARITY_MASK;
                if (cflag & PARENB) {
                        if (cflag & PARODD) {
                                bits |= BITS_PARITY_ODD;
                                dbg("%s - parity = ODD", __func__);
                        } else {
                                bits |= BITS_PARITY_EVEN;
                                dbg("%s - parity = EVEN", __func__);
                        }
                }
                if (cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2))
                        dbg("Parity mode not supported "
                                        "by device\n");
        }

        if ((cflag & CSTOPB) != (old_cflag & CSTOPB)) {
                cp210x_get_config(port, CP210X_GET_LINE_CTL, &bits, 2);
                bits &= ~BITS_STOP_MASK;
                if (cflag & CSTOPB) {
                        bits |= BITS_STOP_2;
                        dbg("%s - stop bits = 2", __func__);
                } else {
                        bits |= BITS_STOP_1;
                        dbg("%s - stop bits = 1", __func__);
                }
                if (cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2))
                        dbg("Number of stop bits requested "
                                        "not supported by device\n");
        }

        if ((cflag & CRTSCTS) != (old_cflag & CRTSCTS)) {
                cp210x_get_config(port, CP210X_GET_FLOW, modem_ctl, 16);
                dbg("%s - read modem controls = 0x%.4x 0x%.4x 0x%.4x 0x%.4x",
                                __func__, 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", __func__);
                } else {
                        modem_ctl[0] &= ~0x7B;
                        modem_ctl[0] |= 0x01;
                        modem_ctl[1] |= 0x40;
                        dbg("%s - flow control = NONE", __func__);
                }

                dbg("%s - write modem controls = 0x%.4x 0x%.4x 0x%.4x 0x%.4x",
                                __func__, modem_ctl[0], modem_ctl[1],
                                modem_ctl[2], modem_ctl[3]);
                cp210x_set_config(port, CP210X_SET_FLOW, modem_ctl, 16);
        }

}

static int cp210x_tiocmset (struct tty_struct *tty, struct file *file,
                unsigned int set, unsigned int clear)
{
        struct usb_serial_port *port = tty->driver_data;
        return cp210x_tiocmset_port(port, file, set, clear);
}

static int cp210x_tiocmset_port(struct usb_serial_port *port, struct file *file,
                unsigned int set, unsigned int clear)
{
        unsigned int control = 0;

        dbg("%s - port %d", __func__, 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", __func__, control);

        return cp210x_set_config(port, CP210X_SET_MHS, &control, 2);
}

static void cp210x_dtr_rts(struct usb_serial_port *p, int on)
{
        if (on)
                cp210x_tiocmset_port(p, NULL,  TIOCM_DTR|TIOCM_RTS, 0);
        else
                cp210x_tiocmset_port(p, NULL,  0, TIOCM_DTR|TIOCM_RTS);
}

static int cp210x_tiocmget (struct tty_struct *tty, struct file *file)
{
        struct usb_serial_port *port = tty->driver_data;
        unsigned int control;
        int result;

        dbg("%s - port %d", __func__, port->number);

        cp210x_get_config(port, CP210X_GET_MDMSTS, &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", __func__, control);

        return result;
}

static int cp210x_carrier_raised(struct usb_serial_port *p)
{
        unsigned int control;
        cp210x_get_config(p, CP210X_GET_MDMSTS, &control, 1);
        if (control & CONTROL_DCD)
                return 1;
        return 0;
}

static void cp210x_break_ctl (struct tty_struct *tty, int break_state)
{
        struct usb_serial_port *port = tty->driver_data;
        unsigned int state;

        dbg("%s - port %d", __func__, port->number);
        if (break_state == 0)
                state = BREAK_OFF;
        else
                state = BREAK_ON;
        dbg("%s - turning break %s", __func__,
                        state == BREAK_OFF ? "off" : "on");
        cp210x_set_config(port, CP210X_SET_BREAK, &state, 2);
}

static int cp210x_startup(struct usb_serial *serial)
{
        /* cp210x buffers behave strangely unless device is reset */
        usb_reset_device(serial->dev);
        return 0;
}

static void cp210x_disconnect(struct usb_serial *serial)
{
        int i;

        dbg("%s", __func__);

        /* Stop reads and writes on all ports */
        for (i = 0; i < serial->num_ports; ++i)
                cp210x_cleanup(serial->port[i]);
}

static int __init cp210x_init(void)
{
        int retval;

        retval = usb_serial_register(&cp210x_device);
        if (retval)
                return retval; /* Failed to register */

        retval = usb_register(&cp210x_driver);
        if (retval) {
                /* Failed to register */
                usb_serial_deregister(&cp210x_device);
                return retval;
        }

        /* Success */
        printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":"
               DRIVER_DESC "\n");
        return 0;
}

static void __exit cp210x_exit(void)
{
        usb_deregister(&cp210x_driver);
        usb_serial_deregister(&cp210x_device);
}

module_init(cp210x_init);
module_exit(cp210x_exit);

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL");

module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Enable verbose debugging messages");