// SPDX-License-Identifier: GPL-2.0
/*
 * usb-serial driver for Quatech USB 2 devices
 *
 * Copyright (C) 2012 Bill Pemberton (wfp5p@virginia.edu)
 *
 *  These devices all have only 1 bulk in and 1 bulk out that is shared
 *  for all serial ports.
 *
 */

#include <linux/unaligned.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/serial.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/serial_reg.h>
#include <linux/uaccess.h>

/* default urb timeout for usb operations */
#define QT2_USB_TIMEOUT USB_CTRL_SET_TIMEOUT

#define QT_OPEN_CLOSE_CHANNEL       0xca
#define QT_SET_GET_DEVICE           0xc2
#define QT_SET_GET_REGISTER         0xc0
#define QT_GET_SET_PREBUF_TRIG_LVL  0xcc
#define QT_SET_ATF                  0xcd
#define QT_TRANSFER_IN              0xc0
#define QT_HW_FLOW_CONTROL_MASK     0xc5
#define QT_SW_FLOW_CONTROL_MASK     0xc6
#define QT2_BREAK_CONTROL           0xc8
#define QT2_GET_SET_UART            0xc1
#define QT2_FLUSH_DEVICE            0xc4
#define QT2_GET_SET_QMCR            0xe1
#define QT2_QMCR_RS232              0x40
#define QT2_QMCR_RS422              0x10

#define  SERIAL_CRTSCTS ((UART_MCR_RTS << 8) | UART_MSR_CTS)

#define  SERIAL_EVEN_PARITY         (UART_LCR_PARITY | UART_LCR_EPAR)

/* status bytes for the device */
#define QT2_CONTROL_BYTE    0x1b
#define QT2_LINE_STATUS     0x00  /* following 1 byte is line status */
#define QT2_MODEM_STATUS    0x01  /* following 1 byte is modem status */
#define QT2_XMIT_HOLD       0x02  /* following 2 bytes are ?? */
#define QT2_CHANGE_PORT     0x03  /* following 1 byte is port to change to */
#define QT2_REC_FLUSH       0x04  /* no following info */
#define QT2_XMIT_FLUSH      0x05  /* no following info */
#define QT2_CONTROL_ESCAPE  0xff  /* pass through previous 2 control bytes */

#define  MAX_BAUD_RATE              921600
#define  DEFAULT_BAUD_RATE          9600

#define QT2_READ_BUFFER_SIZE    512  /* size of read buffer */
#define QT2_WRITE_BUFFER_SIZE   512  /* size of write buffer */
#define QT2_WRITE_CONTROL_SIZE  5    /* control bytes used for a write */

#define DRIVER_DESC "Quatech 2nd gen USB to Serial Driver"

#define USB_VENDOR_ID_QUATECH   0x061d
#define QUATECH_SSU2_100        0xC120  /* RS232 single port */
#define QUATECH_DSU2_100        0xC140  /* RS232 dual port */
#define QUATECH_DSU2_400        0xC150  /* RS232/422/485 dual port */
#define QUATECH_QSU2_100        0xC160  /* RS232 four port */
#define QUATECH_QSU2_400        0xC170  /* RS232/422/485 four port */
#define QUATECH_ESU2_100        0xC1A0  /* RS232 eight port */
#define QUATECH_ESU2_400        0xC180  /* RS232/422/485 eight port */

struct qt2_device_detail {
        int product_id;
        int num_ports;
};

#define QT_DETAILS(prod, ports) \
        .product_id = (prod),   \
        .num_ports = (ports)

static const struct qt2_device_detail qt2_device_details[] = {
        {QT_DETAILS(QUATECH_SSU2_100, 1)},
        {QT_DETAILS(QUATECH_DSU2_400, 2)},
        {QT_DETAILS(QUATECH_DSU2_100, 2)},
        {QT_DETAILS(QUATECH_QSU2_400, 4)},
        {QT_DETAILS(QUATECH_QSU2_100, 4)},
        {QT_DETAILS(QUATECH_ESU2_400, 8)},
        {QT_DETAILS(QUATECH_ESU2_100, 8)},
        {QT_DETAILS(0, 0)}      /* Terminating entry */
};

static const struct usb_device_id id_table[] = {
        {USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_SSU2_100)},
        {USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_DSU2_100)},
        {USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_DSU2_400)},
        {USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_QSU2_100)},
        {USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_QSU2_400)},
        {USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_ESU2_100)},
        {USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_ESU2_400)},
        {}                      /* Terminating entry */
};
MODULE_DEVICE_TABLE(usb, id_table);

struct qt2_serial_private {
        unsigned char current_port;  /* current port for incoming data */

        struct urb      *read_urb;   /* shared among all ports */
        char            *read_buffer;
};

struct qt2_port_private {
        u8   device_port;

        spinlock_t urb_lock;
        bool       urb_in_use;
        struct urb *write_urb;
        char       *write_buffer;

        spinlock_t  lock;
        u8          shadowLSR;
        u8          shadowMSR;

        struct usb_serial_port *port;
};

static void qt2_update_lsr(struct usb_serial_port *port, unsigned char *ch);
static void qt2_update_msr(struct usb_serial_port *port, unsigned char *ch);
static void qt2_write_bulk_callback(struct urb *urb);
static void qt2_read_bulk_callback(struct urb *urb);

static void qt2_release(struct usb_serial *serial)
{
        struct qt2_serial_private *serial_priv;

        serial_priv = usb_get_serial_data(serial);

        usb_kill_urb(serial_priv->read_urb);
        usb_free_urb(serial_priv->read_urb);
        kfree(serial_priv->read_buffer);
        kfree(serial_priv);
}

static inline int calc_baud_divisor(int baudrate)
{
        int divisor, rem;

        divisor = MAX_BAUD_RATE / baudrate;
        rem = MAX_BAUD_RATE % baudrate;
        /* Round to nearest divisor */
        if (((rem * 2) >= baudrate) && (baudrate != 110))
                divisor++;

        return divisor;
}

static inline int qt2_set_port_config(struct usb_device *dev,
                                      unsigned char port_number,
                                      u16 baudrate, u16 lcr)
{
        int divisor = calc_baud_divisor(baudrate);
        u16 index = ((u16) (lcr << 8) | (u16) (port_number));

        return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                               QT2_GET_SET_UART, 0x40,
                               divisor, index, NULL, 0, QT2_USB_TIMEOUT);
}

static inline int qt2_control_msg(struct usb_device *dev,
                                  u8 request, u16 data, u16 index)
{
        return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                               request, 0x40, data, index,
                               NULL, 0, QT2_USB_TIMEOUT);
}

static inline int qt2_getregister(struct usb_device *dev,
                                  u8 uart,
                                  u8 reg,
                                  u8 *data)
{
        int ret;

        ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
                              QT_SET_GET_REGISTER, 0xc0, reg,
                              uart, data, sizeof(*data), QT2_USB_TIMEOUT);
        if (ret < (int)sizeof(*data)) {
                if (ret >= 0)
                        ret = -EIO;
        }

        return ret;
}

static inline int qt2_setregister(struct usb_device *dev,
                                  u8 uart, u8 reg, u16 data)
{
        u16 value = (data << 8) | reg;

        return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                               QT_SET_GET_REGISTER, 0x40, value, uart,
                               NULL, 0, QT2_USB_TIMEOUT);
}

static inline int update_mctrl(struct qt2_port_private *port_priv,
                               unsigned int set, unsigned int clear)
{
        struct usb_serial_port *port = port_priv->port;
        struct usb_device *dev = port->serial->dev;
        unsigned urb_value;
        int status;

        if (((set | clear) & (TIOCM_DTR | TIOCM_RTS)) == 0) {
                dev_dbg(&port->dev,
                        "update_mctrl - DTR|RTS not being set|cleared\n");
                return 0;       /* no change */
        }

        clear &= ~set;  /* 'set' takes precedence over 'clear' */
        urb_value = 0;
        if (set & TIOCM_DTR)
                urb_value |= UART_MCR_DTR;
        if (set & TIOCM_RTS)
                urb_value |= UART_MCR_RTS;

        status = qt2_setregister(dev, port_priv->device_port, UART_MCR,
                                 urb_value);
        if (status < 0)
                dev_err(&port->dev,
                        "update_mctrl - Error from MODEM_CTRL urb: %i\n",
                        status);
        return status;
}

static int qt2_calc_num_ports(struct usb_serial *serial,
                                        struct usb_serial_endpoints *epds)
{
        struct qt2_device_detail d;
        int i;

        for (i = 0; d = qt2_device_details[i], d.product_id != 0; i++) {
                if (d.product_id == le16_to_cpu(serial->dev->descriptor.idProduct))
                        return d.num_ports;
        }

        /* we didn't recognize the device */
        dev_err(&serial->dev->dev,
                 "don't know the number of ports, assuming 1\n");

        return 1;
}

static void qt2_set_termios(struct tty_struct *tty,
                            struct usb_serial_port *port,
                            const struct ktermios *old_termios)
{
        struct usb_device *dev = port->serial->dev;
        struct qt2_port_private *port_priv;
        struct ktermios *termios = &tty->termios;
        u16 baud;
        unsigned int cflag = termios->c_cflag;
        u16 new_lcr = 0;
        int status;

        port_priv = usb_get_serial_port_data(port);

        if (cflag & PARENB) {
                if (cflag & PARODD)
                        new_lcr |= UART_LCR_PARITY;
                else
                        new_lcr |= SERIAL_EVEN_PARITY;
        }

        new_lcr |= UART_LCR_WLEN(tty_get_char_size(cflag));

        baud = tty_get_baud_rate(tty);
        if (!baud)
                baud = 9600;

        status = qt2_set_port_config(dev, port_priv->device_port, baud,
                                     new_lcr);
        if (status < 0)
                dev_err(&port->dev, "%s - qt2_set_port_config failed: %i\n",
                        __func__, status);

        if (cflag & CRTSCTS)
                status = qt2_control_msg(dev, QT_HW_FLOW_CONTROL_MASK,
                                         SERIAL_CRTSCTS,
                                         port_priv->device_port);
        else
                status = qt2_control_msg(dev, QT_HW_FLOW_CONTROL_MASK,
                                         0, port_priv->device_port);
        if (status < 0)
                dev_err(&port->dev, "%s - set HW flow control failed: %i\n",
                        __func__, status);

        if (I_IXOFF(tty) || I_IXON(tty)) {
                u16 x = ((u16) (START_CHAR(tty) << 8) | (u16) (STOP_CHAR(tty)));

                status = qt2_control_msg(dev, QT_SW_FLOW_CONTROL_MASK,
                                         x, port_priv->device_port);
        } else
                status = qt2_control_msg(dev, QT_SW_FLOW_CONTROL_MASK,
                                         0, port_priv->device_port);

        if (status < 0)
                dev_err(&port->dev, "%s - set SW flow control failed: %i\n",
                        __func__, status);

}

static int qt2_open(struct tty_struct *tty, struct usb_serial_port *port)
{
        struct usb_serial *serial;
        struct qt2_port_private *port_priv;
        u8 *data;
        u16 device_port;
        int status;
        unsigned long flags;

        device_port = port->port_number;

        serial = port->serial;

        port_priv = usb_get_serial_port_data(port);

        /* set the port to RS232 mode */
        status = qt2_control_msg(serial->dev, QT2_GET_SET_QMCR,
                                 QT2_QMCR_RS232, device_port);
        if (status < 0) {
                dev_err(&port->dev,
                        "%s failed to set RS232 mode for port %i error %i\n",
                        __func__, device_port, status);
                return status;
        }

        data = kzalloc(2, GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        /* open the port */
        status = usb_control_msg(serial->dev,
                                 usb_rcvctrlpipe(serial->dev, 0),
                                 QT_OPEN_CLOSE_CHANNEL,
                                 0xc0, 0,
                                 device_port, data, 2, QT2_USB_TIMEOUT);

        if (status < 2) {
                dev_err(&port->dev, "%s - open port failed %i\n", __func__,
                        status);
                if (status >= 0)
                        status = -EIO;
                kfree(data);
                return status;
        }

        spin_lock_irqsave(&port_priv->lock, flags);
        port_priv->shadowLSR = data[0];
        port_priv->shadowMSR = data[1];
        spin_unlock_irqrestore(&port_priv->lock, flags);

        kfree(data);

        /* set to default speed and 8bit word size */
        status = qt2_set_port_config(serial->dev, device_port,
                                     DEFAULT_BAUD_RATE, UART_LCR_WLEN8);
        if (status < 0) {
                dev_err(&port->dev, "%s - initial setup failed (%i)\n",
                        __func__, device_port);
                return status;
        }

        port_priv->device_port = (u8) device_port;

        if (tty)
                qt2_set_termios(tty, port, &tty->termios);

        return 0;

}

static void qt2_close(struct usb_serial_port *port)
{
        struct usb_serial *serial;
        struct qt2_port_private *port_priv;
        int i;

        serial = port->serial;
        port_priv = usb_get_serial_port_data(port);

        usb_kill_urb(port_priv->write_urb);

        /* flush the port transmit buffer */
        i = usb_control_msg(serial->dev,
                            usb_sndctrlpipe(serial->dev, 0),
                            QT2_FLUSH_DEVICE, 0x40, 1,
                            port_priv->device_port, NULL, 0, QT2_USB_TIMEOUT);

        if (i < 0)
                dev_err(&port->dev, "%s - transmit buffer flush failed: %i\n",
                        __func__, i);

        /* flush the port receive buffer */
        i = usb_control_msg(serial->dev,
                            usb_sndctrlpipe(serial->dev, 0),
                            QT2_FLUSH_DEVICE, 0x40, 0,
                            port_priv->device_port, NULL, 0, QT2_USB_TIMEOUT);

        if (i < 0)
                dev_err(&port->dev, "%s - receive buffer flush failed: %i\n",
                        __func__, i);

        /* close the port */
        i = usb_control_msg(serial->dev,
                            usb_sndctrlpipe(serial->dev, 0),
                            QT_OPEN_CLOSE_CHANNEL,
                            0x40, 0,
                            port_priv->device_port, NULL, 0, QT2_USB_TIMEOUT);

        if (i < 0)
                dev_err(&port->dev, "%s - close port failed %i\n",
                        __func__, i);
}

static void qt2_disconnect(struct usb_serial *serial)
{
        struct qt2_serial_private *serial_priv = usb_get_serial_data(serial);

        usb_kill_urb(serial_priv->read_urb);
}

static void qt2_process_status(struct usb_serial_port *port, unsigned char *ch)
{
        switch (*ch) {
        case QT2_LINE_STATUS:
                qt2_update_lsr(port, ch + 1);
                break;
        case QT2_MODEM_STATUS:
                qt2_update_msr(port, ch + 1);
                break;
        }
}

static void qt2_process_read_urb(struct urb *urb)
{
        struct usb_serial *serial;
        struct qt2_serial_private *serial_priv;
        struct usb_serial_port *port;
        bool escapeflag;
        unsigned char *ch;
        int i;
        unsigned char newport;
        int len = urb->actual_length;

        if (!len)
                return;

        ch = urb->transfer_buffer;
        serial = urb->context;
        serial_priv = usb_get_serial_data(serial);
        port = serial->port[serial_priv->current_port];

        for (i = 0; i < urb->actual_length; i++) {
                ch = (unsigned char *)urb->transfer_buffer + i;
                if ((i <= (len - 3)) &&
                    (*ch == QT2_CONTROL_BYTE) &&
                    (*(ch + 1) == QT2_CONTROL_BYTE)) {
                        escapeflag = false;
                        switch (*(ch + 2)) {
                        case QT2_LINE_STATUS:
                        case QT2_MODEM_STATUS:
                                if (i > (len - 4)) {
                                        dev_warn(&port->dev,
                                                 "%s - status message too short\n",
                                                __func__);
                                        break;
                                }
                                qt2_process_status(port, ch + 2);
                                i += 3;
                                escapeflag = true;
                                break;
                        case QT2_XMIT_HOLD:
                                if (i > (len - 5)) {
                                        dev_warn(&port->dev,
                                                 "%s - xmit_empty message too short\n",
                                                 __func__);
                                        break;
                                }
                                /* bytes_written = (ch[1] << 4) + ch[0]; */
                                i += 4;
                                escapeflag = true;
                                break;
                        case QT2_CHANGE_PORT:
                                if (i > (len - 4)) {
                                        dev_warn(&port->dev,
                                                 "%s - change_port message too short\n",
                                                 __func__);
                                        break;
                                }
                                tty_flip_buffer_push(&port->port);

                                newport = *(ch + 3);

                                if (newport >= serial->num_ports) {
                                        dev_err(&port->dev,
                                                "%s - port change to invalid port: %i\n",
                                                __func__, newport);
                                        break;
                                }

                                serial_priv->current_port = newport;
                                port = serial->port[serial_priv->current_port];
                                i += 3;
                                escapeflag = true;
                                break;
                        case QT2_REC_FLUSH:
                        case QT2_XMIT_FLUSH:
                                i += 2;
                                escapeflag = true;
                                break;
                        case QT2_CONTROL_ESCAPE:
                                tty_insert_flip_string(&port->port, ch, 2);
                                i += 2;
                                escapeflag = true;
                                break;
                        default:
                                dev_warn(&port->dev,
                                         "%s - unsupported command %i\n",
                                         __func__, *(ch + 2));
                                break;
                        }
                        if (escapeflag)
                                continue;
                }

                tty_insert_flip_char(&port->port, *ch, TTY_NORMAL);
        }

        tty_flip_buffer_push(&port->port);
}

static void qt2_write_bulk_callback(struct urb *urb)
{
        struct usb_serial_port *port;
        struct qt2_port_private *port_priv;
        unsigned long flags;

        port = urb->context;
        port_priv = usb_get_serial_port_data(port);

        spin_lock_irqsave(&port_priv->urb_lock, flags);

        port_priv->urb_in_use = false;
        usb_serial_port_softint(port);

        spin_unlock_irqrestore(&port_priv->urb_lock, flags);

}

static void qt2_read_bulk_callback(struct urb *urb)
{
        struct usb_serial *serial = urb->context;
        int status;

        if (urb->status) {
                dev_warn(&serial->dev->dev,
                         "%s - non-zero urb status: %i\n", __func__,
                         urb->status);
                return;
        }

        qt2_process_read_urb(urb);

        status = usb_submit_urb(urb, GFP_ATOMIC);
        if (status != 0)
                dev_err(&serial->dev->dev,
                        "%s - resubmit read urb failed: %i\n",
                        __func__, status);
}

static int qt2_setup_urbs(struct usb_serial *serial)
{
        struct usb_serial_port *port0;
        struct qt2_serial_private *serial_priv;
        int status;

        port0 = serial->port[0];

        serial_priv = usb_get_serial_data(serial);
        serial_priv->read_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!serial_priv->read_urb)
                return -ENOMEM;

        usb_fill_bulk_urb(serial_priv->read_urb, serial->dev,
                          usb_rcvbulkpipe(serial->dev,
                                          port0->bulk_in_endpointAddress),
                          serial_priv->read_buffer,
                          QT2_READ_BUFFER_SIZE,
                          qt2_read_bulk_callback, serial);

        status = usb_submit_urb(serial_priv->read_urb, GFP_KERNEL);
        if (status != 0) {
                dev_err(&serial->dev->dev,
                        "%s - submit read urb failed %i\n", __func__, status);
                usb_free_urb(serial_priv->read_urb);
                return status;
        }

        return 0;
}

static int qt2_attach(struct usb_serial *serial)
{
        struct qt2_serial_private *serial_priv;
        int status;

        /* power on unit */
        status = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
                                 0xc2, 0x40, 0x8000, 0, NULL, 0,
                                 QT2_USB_TIMEOUT);
        if (status < 0) {
                dev_err(&serial->dev->dev,
                        "%s - failed to power on unit: %i\n", __func__, status);
                return status;
        }

        serial_priv = kzalloc_obj(*serial_priv);
        if (!serial_priv)
                return -ENOMEM;

        serial_priv->read_buffer = kmalloc(QT2_READ_BUFFER_SIZE, GFP_KERNEL);
        if (!serial_priv->read_buffer) {
                status = -ENOMEM;
                goto err_buf;
        }

        usb_set_serial_data(serial, serial_priv);

        status = qt2_setup_urbs(serial);
        if (status != 0)
                goto attach_failed;

        return 0;

attach_failed:
        kfree(serial_priv->read_buffer);
err_buf:
        kfree(serial_priv);
        return status;
}

static int qt2_port_probe(struct usb_serial_port *port)
{
        struct usb_serial *serial = port->serial;
        struct qt2_port_private *port_priv;
        u8 bEndpointAddress;

        port_priv = kzalloc_obj(*port_priv);
        if (!port_priv)
                return -ENOMEM;

        spin_lock_init(&port_priv->lock);
        spin_lock_init(&port_priv->urb_lock);
        port_priv->port = port;

        port_priv->write_buffer = kmalloc(QT2_WRITE_BUFFER_SIZE, GFP_KERNEL);
        if (!port_priv->write_buffer)
                goto err_buf;

        port_priv->write_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!port_priv->write_urb)
                goto err_urb;

        bEndpointAddress = serial->port[0]->bulk_out_endpointAddress;
        usb_fill_bulk_urb(port_priv->write_urb, serial->dev,
                                usb_sndbulkpipe(serial->dev, bEndpointAddress),
                                port_priv->write_buffer,
                                QT2_WRITE_BUFFER_SIZE,
                                qt2_write_bulk_callback, port);

        usb_set_serial_port_data(port, port_priv);

        return 0;
err_urb:
        kfree(port_priv->write_buffer);
err_buf:
        kfree(port_priv);
        return -ENOMEM;
}

static void qt2_port_remove(struct usb_serial_port *port)
{
        struct qt2_port_private *port_priv;

        port_priv = usb_get_serial_port_data(port);
        usb_free_urb(port_priv->write_urb);
        kfree(port_priv->write_buffer);
        kfree(port_priv);
}

static int qt2_tiocmget(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct usb_device *dev = port->serial->dev;
        struct qt2_port_private *port_priv = usb_get_serial_port_data(port);
        u8 *d;
        int r;

        d = kzalloc(2, GFP_KERNEL);
        if (!d)
                return -ENOMEM;

        r = qt2_getregister(dev, port_priv->device_port, UART_MCR, d);
        if (r < 0)
                goto mget_out;

        r = qt2_getregister(dev, port_priv->device_port, UART_MSR, d + 1);
        if (r < 0)
                goto mget_out;

        r = (d[0] & UART_MCR_DTR ? TIOCM_DTR : 0) |
            (d[0] & UART_MCR_RTS ? TIOCM_RTS : 0) |
            (d[1] & UART_MSR_CTS ? TIOCM_CTS : 0) |
            (d[1] & UART_MSR_DCD ? TIOCM_CAR : 0) |
            (d[1] & UART_MSR_RI ? TIOCM_RI : 0) |
            (d[1] & UART_MSR_DSR ? TIOCM_DSR : 0);

mget_out:
        kfree(d);
        return r;
}

static int qt2_tiocmset(struct tty_struct *tty,
                        unsigned int set, unsigned int clear)
{
        struct qt2_port_private *port_priv;

        port_priv = usb_get_serial_port_data(tty->driver_data);
        return update_mctrl(port_priv, set, clear);
}

static int qt2_break_ctl(struct tty_struct *tty, int break_state)
{
        struct usb_serial_port *port = tty->driver_data;
        struct qt2_port_private *port_priv;
        int status;
        u16 val;

        port_priv = usb_get_serial_port_data(port);

        val = (break_state == -1) ? 1 : 0;

        status = qt2_control_msg(port->serial->dev, QT2_BREAK_CONTROL,
                                 val, port_priv->device_port);
        if (status < 0) {
                dev_warn(&port->dev,
                         "%s - failed to send control message: %i\n", __func__,
                         status);
                return status;
        }

        return 0;
}



static void qt2_dtr_rts(struct usb_serial_port *port, int on)
{
        struct usb_device *dev = port->serial->dev;
        struct qt2_port_private *port_priv = usb_get_serial_port_data(port);

        /* Disable flow control */
        if (!on) {
                if (qt2_setregister(dev, port_priv->device_port,
                                           UART_MCR, 0) < 0)
                        dev_warn(&port->dev, "error from flowcontrol urb\n");
        }
        /* drop RTS and DTR */
        if (on)
                update_mctrl(port_priv, TIOCM_DTR | TIOCM_RTS, 0);
        else
                update_mctrl(port_priv, 0, TIOCM_DTR | TIOCM_RTS);
}

static void qt2_update_msr(struct usb_serial_port *port, unsigned char *ch)
{
        struct qt2_port_private *port_priv;
        u8 newMSR = (u8) *ch;
        unsigned long flags;

        /* May be called from qt2_process_read_urb() for an unbound port. */
        port_priv = usb_get_serial_port_data(port);
        if (!port_priv)
                return;

        spin_lock_irqsave(&port_priv->lock, flags);
        port_priv->shadowMSR = newMSR;
        spin_unlock_irqrestore(&port_priv->lock, flags);

        if (newMSR & UART_MSR_ANY_DELTA) {
                /* update input line counters */
                if (newMSR & UART_MSR_DCTS)
                        port->icount.cts++;
                if (newMSR & UART_MSR_DDSR)
                        port->icount.dsr++;
                if (newMSR & UART_MSR_DDCD)
                        port->icount.dcd++;
                if (newMSR & UART_MSR_TERI)
                        port->icount.rng++;

                wake_up_interruptible(&port->port.delta_msr_wait);
        }
}

static void qt2_update_lsr(struct usb_serial_port *port, unsigned char *ch)
{
        struct qt2_port_private *port_priv;
        struct async_icount *icount;
        unsigned long flags;
        u8 newLSR = (u8) *ch;

        /* May be called from qt2_process_read_urb() for an unbound port. */
        port_priv = usb_get_serial_port_data(port);
        if (!port_priv)
                return;

        if (newLSR & UART_LSR_BI)
                newLSR &= (u8) (UART_LSR_OE | UART_LSR_BI);

        spin_lock_irqsave(&port_priv->lock, flags);
        port_priv->shadowLSR = newLSR;
        spin_unlock_irqrestore(&port_priv->lock, flags);

        icount = &port->icount;

        if (newLSR & UART_LSR_BRK_ERROR_BITS) {

                if (newLSR & UART_LSR_BI)
                        icount->brk++;

                if (newLSR & UART_LSR_OE)
                        icount->overrun++;

                if (newLSR & UART_LSR_PE)
                        icount->parity++;

                if (newLSR & UART_LSR_FE)
                        icount->frame++;
        }

}

static unsigned int qt2_write_room(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct qt2_port_private *port_priv;
        unsigned long flags;
        unsigned int r;

        port_priv = usb_get_serial_port_data(port);

        spin_lock_irqsave(&port_priv->urb_lock, flags);

        if (port_priv->urb_in_use)
                r = 0;
        else
                r = QT2_WRITE_BUFFER_SIZE - QT2_WRITE_CONTROL_SIZE;

        spin_unlock_irqrestore(&port_priv->urb_lock, flags);

        return r;
}

static int qt2_write(struct tty_struct *tty,
                     struct usb_serial_port *port,
                     const unsigned char *buf, int count)
{
        struct qt2_port_private *port_priv;
        struct urb *write_urb;
        unsigned char *data;
        unsigned long flags;
        int status;
        int bytes_out = 0;

        port_priv = usb_get_serial_port_data(port);

        if (port_priv->write_urb == NULL) {
                dev_err(&port->dev, "%s - no output urb\n", __func__);
                return 0;
        }
        write_urb = port_priv->write_urb;

        count = min(count, QT2_WRITE_BUFFER_SIZE - QT2_WRITE_CONTROL_SIZE);

        data = write_urb->transfer_buffer;
        spin_lock_irqsave(&port_priv->urb_lock, flags);
        if (port_priv->urb_in_use) {
                dev_err(&port->dev, "qt2_write - urb is in use\n");
                goto write_out;
        }

        *data++ = QT2_CONTROL_BYTE;
        *data++ = QT2_CONTROL_BYTE;
        *data++ = port_priv->device_port;
        put_unaligned_le16(count, data);
        data += 2;
        memcpy(data, buf, count);

        write_urb->transfer_buffer_length = count + QT2_WRITE_CONTROL_SIZE;

        status = usb_submit_urb(write_urb, GFP_ATOMIC);
        if (status == 0) {
                port_priv->urb_in_use = true;
                bytes_out += count;
        }

write_out:
        spin_unlock_irqrestore(&port_priv->urb_lock, flags);
        return bytes_out;
}


static struct usb_serial_driver qt2_device = {
        .driver = {
                .name = "quatech-serial",
        },
        .description         = DRIVER_DESC,
        .id_table            = id_table,
        .open                = qt2_open,
        .close               = qt2_close,
        .write               = qt2_write,
        .write_room          = qt2_write_room,
        .calc_num_ports      = qt2_calc_num_ports,
        .attach              = qt2_attach,
        .release             = qt2_release,
        .disconnect          = qt2_disconnect,
        .port_probe          = qt2_port_probe,
        .port_remove         = qt2_port_remove,
        .dtr_rts             = qt2_dtr_rts,
        .break_ctl           = qt2_break_ctl,
        .tiocmget            = qt2_tiocmget,
        .tiocmset            = qt2_tiocmset,
        .tiocmiwait          = usb_serial_generic_tiocmiwait,
        .get_icount          = usb_serial_generic_get_icount,
        .set_termios         = qt2_set_termios,
};

static struct usb_serial_driver *const serial_drivers[] = {
        &qt2_device, NULL
};

module_usb_serial_driver(serial_drivers, id_table);

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL v2");