/*
 * spcp8x5 USB to serial adaptor driver
 *
 * Copyright (C) 2006 Linxb (xubin.lin@worldplus.com.cn)
 * Copyright (C) 2006 S1 Corp.
 *
 * Original driver for 2.6.10 pl2303 driver by
 *   Greg Kroah-Hartman (greg@kroah.com)
 * Changes for 2.6.20 by Harald Klein <hari@vt100.at>
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 *
 */
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.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/spinlock.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>


/* Version Information */
#define DRIVER_VERSION  "v0.04"
#define DRIVER_DESC     "SPCP8x5 USB to serial adaptor driver"

static int debug;

#define SPCP8x5_007_VID         0x04FC
#define SPCP8x5_007_PID         0x0201
#define SPCP8x5_008_VID         0x04fc
#define SPCP8x5_008_PID         0x0235
#define SPCP8x5_PHILIPS_VID     0x0471
#define SPCP8x5_PHILIPS_PID     0x081e
#define SPCP8x5_INTERMATIC_VID  0x04FC
#define SPCP8x5_INTERMATIC_PID  0x0204
#define SPCP8x5_835_VID         0x04fc
#define SPCP8x5_835_PID         0x0231

static struct usb_device_id id_table [] = {
        { USB_DEVICE(SPCP8x5_PHILIPS_VID , SPCP8x5_PHILIPS_PID)},
        { USB_DEVICE(SPCP8x5_INTERMATIC_VID, SPCP8x5_INTERMATIC_PID)},
        { USB_DEVICE(SPCP8x5_835_VID, SPCP8x5_835_PID)},
        { USB_DEVICE(SPCP8x5_008_VID, SPCP8x5_008_PID)},
        { USB_DEVICE(SPCP8x5_007_VID, SPCP8x5_007_PID)},
        { }                                     /* Terminating entry */
};
MODULE_DEVICE_TABLE(usb, id_table);

struct spcp8x5_usb_ctrl_arg {
        u8      type;
        u8      cmd;
        u8      cmd_type;
        u16     value;
        u16     index;
        u16     length;
};

/* wait 30s before close */
#define SPCP8x5_CLOSING_WAIT    (30*HZ)

#define SPCP8x5_BUF_SIZE        1024


/* spcp8x5 spec register define */
#define MCR_CONTROL_LINE_RTS            0x02
#define MCR_CONTROL_LINE_DTR            0x01
#define MCR_DTR                         0x01
#define MCR_RTS                         0x02

#define MSR_STATUS_LINE_DCD             0x80
#define MSR_STATUS_LINE_RI              0x40
#define MSR_STATUS_LINE_DSR             0x20
#define MSR_STATUS_LINE_CTS             0x10

/* verdor command here , we should define myself */
#define SET_DEFAULT                     0x40
#define SET_DEFAULT_TYPE                0x20

#define SET_UART_FORMAT                 0x40
#define SET_UART_FORMAT_TYPE            0x21
#define SET_UART_FORMAT_SIZE_5          0x00
#define SET_UART_FORMAT_SIZE_6          0x01
#define SET_UART_FORMAT_SIZE_7          0x02
#define SET_UART_FORMAT_SIZE_8          0x03
#define SET_UART_FORMAT_STOP_1          0x00
#define SET_UART_FORMAT_STOP_2          0x04
#define SET_UART_FORMAT_PAR_NONE        0x00
#define SET_UART_FORMAT_PAR_ODD         0x10
#define SET_UART_FORMAT_PAR_EVEN        0x30
#define SET_UART_FORMAT_PAR_MASK        0xD0
#define SET_UART_FORMAT_PAR_SPACE       0x90

#define GET_UART_STATUS_TYPE            0xc0
#define GET_UART_STATUS                 0x22
#define GET_UART_STATUS_MSR             0x06

#define SET_UART_STATUS                 0x40
#define SET_UART_STATUS_TYPE            0x23
#define SET_UART_STATUS_MCR             0x0004
#define SET_UART_STATUS_MCR_DTR         0x01
#define SET_UART_STATUS_MCR_RTS         0x02
#define SET_UART_STATUS_MCR_LOOP        0x10

#define SET_WORKING_MODE                0x40
#define SET_WORKING_MODE_TYPE           0x24
#define SET_WORKING_MODE_U2C            0x00
#define SET_WORKING_MODE_RS485          0x01
#define SET_WORKING_MODE_PDMA           0x02
#define SET_WORKING_MODE_SPP            0x03

#define SET_FLOWCTL_CHAR                0x40
#define SET_FLOWCTL_CHAR_TYPE           0x25

#define GET_VERSION                     0xc0
#define GET_VERSION_TYPE                0x26

#define SET_REGISTER                    0x40
#define SET_REGISTER_TYPE               0x27

#define GET_REGISTER                    0xc0
#define GET_REGISTER_TYPE               0x28

#define SET_RAM                         0x40
#define SET_RAM_TYPE                    0x31

#define GET_RAM                         0xc0
#define GET_RAM_TYPE                    0x32

/* how come ??? */
#define UART_STATE                      0x08
#define UART_STATE_TRANSIENT_MASK       0x74
#define UART_DCD                        0x01
#define UART_DSR                        0x02
#define UART_BREAK_ERROR                0x04
#define UART_RING                       0x08
#define UART_FRAME_ERROR                0x10
#define UART_PARITY_ERROR               0x20
#define UART_OVERRUN_ERROR              0x40
#define UART_CTS                        0x80

enum spcp8x5_type {
        SPCP825_007_TYPE,
        SPCP825_008_TYPE,
        SPCP825_PHILIP_TYPE,
        SPCP825_INTERMATIC_TYPE,
        SPCP835_TYPE,
};

/* 1st in 1st out buffer 4 driver */
struct ringbuf {
        unsigned int    buf_size;
        char            *buf_buf;
        char            *buf_get;
        char            *buf_put;
};

/* alloc the ring buf and alloc the buffer itself */
static inline struct ringbuf *alloc_ringbuf(unsigned int size)
{
        struct ringbuf *pb;

        if (size == 0)
                return NULL;

        pb = kmalloc(sizeof(*pb), GFP_KERNEL);
        if (pb == NULL)
                return NULL;

        pb->buf_buf = kmalloc(size, GFP_KERNEL);
        if (pb->buf_buf == NULL) {
                kfree(pb);
                return NULL;
        }

        pb->buf_size = size;
        pb->buf_get = pb->buf_put = pb->buf_buf;

        return pb;
}

/* free the ring buf and the buffer itself */
static inline void free_ringbuf(struct ringbuf *pb)
{
        if (pb != NULL) {
                kfree(pb->buf_buf);
                kfree(pb);
        }
}

/* clear pipo , juest repoint the pointer here */
static inline void clear_ringbuf(struct ringbuf *pb)
{
        if (pb != NULL)
                pb->buf_get = pb->buf_put;
}

/* get the number of data in the pipo */
static inline unsigned int ringbuf_avail_data(struct ringbuf *pb)
{
        if (pb == NULL)
                return 0;
        return (pb->buf_size + pb->buf_put - pb->buf_get) % pb->buf_size;
}

/* get the number of space in the pipo */
static inline unsigned int ringbuf_avail_space(struct ringbuf *pb)
{
        if (pb == NULL)
                return 0;
        return (pb->buf_size + pb->buf_get - pb->buf_put - 1) % pb->buf_size;
}

/* put count data into pipo */
static unsigned int put_ringbuf(struct ringbuf *pb, const char *buf,
                                unsigned int count)
{
        unsigned int len;

        if (pb == NULL)
                return 0;

        len  = ringbuf_avail_space(pb);
        if (count > len)
                count = len;

        if (count == 0)
                return 0;

        len = pb->buf_buf + pb->buf_size - pb->buf_put;
        if (count > len) {
                memcpy(pb->buf_put, buf, len);
                memcpy(pb->buf_buf, buf+len, count - len);
                pb->buf_put = pb->buf_buf + count - len;
        } else {
                memcpy(pb->buf_put, buf, count);
                if (count < len)
                        pb->buf_put += count;
                else /* count == len */
                        pb->buf_put = pb->buf_buf;
        }
        return count;
}

/* get count data from pipo */
static unsigned int get_ringbuf(struct ringbuf *pb, char *buf,
                                unsigned int count)
{
        unsigned int len;

        if (pb == NULL || buf == NULL)
                return 0;

        len = ringbuf_avail_data(pb);
        if (count > len)
                count = len;

        if (count == 0)
                return 0;

        len = pb->buf_buf + pb->buf_size - pb->buf_get;
        if (count > len) {
                memcpy(buf, pb->buf_get, len);
                memcpy(buf+len, pb->buf_buf, count - len);
                pb->buf_get = pb->buf_buf + count - len;
        } else {
                memcpy(buf, pb->buf_get, count);
                if (count < len)
                        pb->buf_get += count;
                else /* count == len */
                        pb->buf_get = pb->buf_buf;
        }

        return count;
}

static struct usb_driver spcp8x5_driver = {
        .name =                 "spcp8x5",
        .probe =                usb_serial_probe,
        .disconnect =           usb_serial_disconnect,
        .id_table =             id_table,
        .no_dynamic_id =        1,
};


struct spcp8x5_private {
        spinlock_t      lock;
        struct ringbuf  *buf;
        int             write_urb_in_use;
        enum spcp8x5_type       type;
        wait_queue_head_t       delta_msr_wait;
        u8                      line_control;
        u8                      line_status;
};

/* desc : when device plug in,this function would be called.
 * thanks to usb_serial subsystem,then do almost every things for us. And what
 * we should do just alloc the buffer */
static int spcp8x5_startup(struct usb_serial *serial)
{
        struct spcp8x5_private *priv;
        int i;
        enum spcp8x5_type type = SPCP825_007_TYPE;
        u16 product = le16_to_cpu(serial->dev->descriptor.idProduct);

        if (product == 0x0201)
                type = SPCP825_007_TYPE;
        else if (product == 0x0231)
                type = SPCP835_TYPE;
        else if (product == 0x0235)
                type = SPCP825_008_TYPE;
        else if (product == 0x0204)
                type = SPCP825_INTERMATIC_TYPE;
        else if (product == 0x0471 &&
                 serial->dev->descriptor.idVendor == cpu_to_le16(0x081e))
                type = SPCP825_PHILIP_TYPE;
        dev_dbg(&serial->dev->dev, "device type = %d\n", (int)type);

        for (i = 0; i < serial->num_ports; ++i) {
                priv = kzalloc(sizeof(struct spcp8x5_private), GFP_KERNEL);
                if (!priv)
                        goto cleanup;

                spin_lock_init(&priv->lock);
                priv->buf = alloc_ringbuf(SPCP8x5_BUF_SIZE);
                if (priv->buf == NULL)
                        goto cleanup2;

                init_waitqueue_head(&priv->delta_msr_wait);
                priv->type = type;
                usb_set_serial_port_data(serial->port[i] , priv);

        }

        return 0;

cleanup2:
        kfree(priv);
cleanup:
        for (--i; i >= 0; --i) {
                priv = usb_get_serial_port_data(serial->port[i]);
                free_ringbuf(priv->buf);
                kfree(priv);
                usb_set_serial_port_data(serial->port[i] , NULL);
        }
        return -ENOMEM;
}

/* call when the device plug out. free all the memory alloced by probe */
static void spcp8x5_release(struct usb_serial *serial)
{
        int i;
        struct spcp8x5_private *priv;

        for (i = 0; i < serial->num_ports; i++) {
                priv = usb_get_serial_port_data(serial->port[i]);
                if (priv) {
                        free_ringbuf(priv->buf);
                        kfree(priv);
                }
        }
}

/* set the modem control line of the device.
 * NOTE spcp825-007 not supported this */
static int spcp8x5_set_ctrlLine(struct usb_device *dev, u8 value,
                                enum spcp8x5_type type)
{
        int retval;
        u8 mcr = 0 ;

        if (type == SPCP825_007_TYPE)
                return -EPERM;

        mcr = (unsigned short)value;
        retval = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                                 SET_UART_STATUS_TYPE, SET_UART_STATUS,
                                 mcr, 0x04, NULL, 0, 100);
        if (retval != 0)
                dev_dbg(&dev->dev, "usb_control_msg return %#x\n", retval);
        return retval;
}

/* get the modem status register of the device
 * NOTE spcp825-007 not supported this */
static int spcp8x5_get_msr(struct usb_device *dev, u8 *status,
                           enum spcp8x5_type type)
{
        u8 *status_buffer;
        int ret;

        /* I return Permited not support here but seem inval device
         * is more fix */
        if (type == SPCP825_007_TYPE)
                return -EPERM;
        if (status == NULL)
                return -EINVAL;

        status_buffer = kmalloc(1, GFP_KERNEL);
        if (!status_buffer)
                return -ENOMEM;
        status_buffer[0] = status[0];

        ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
                              GET_UART_STATUS, GET_UART_STATUS_TYPE,
                              0, GET_UART_STATUS_MSR, status_buffer, 1, 100);
        if (ret < 0)
                dev_dbg(&dev->dev, "Get MSR = 0x%p failed (error = %d)",
                        status_buffer, ret);

        dev_dbg(&dev->dev, "0xc0:0x22:0:6  %d - 0x%p ", ret, status_buffer);
        status[0] = status_buffer[0];
        kfree(status_buffer);

        return ret;
}

/* select the work mode.
 * NOTE this function not supported by spcp825-007 */
static void spcp8x5_set_workMode(struct usb_device *dev, u16 value,
                                 u16 index, enum spcp8x5_type type)
{
        int ret;

        /* I return Permited not support here but seem inval device
         * is more fix */
        if (type == SPCP825_007_TYPE)
                return;

        ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                              SET_WORKING_MODE_TYPE, SET_WORKING_MODE,
                              value, index, NULL, 0, 100);
        dev_dbg(&dev->dev, "value = %#x , index = %#x\n", value, index);
        if (ret < 0)
                dev_dbg(&dev->dev,
                        "RTSCTS usb_control_msg(enable flowctrl) = %d\n", ret);
}

static int spcp8x5_carrier_raised(struct usb_serial_port *port)
{
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        if (priv->line_status & MSR_STATUS_LINE_DCD)
                return 1;
        return 0;
}

static void spcp8x5_dtr_rts(struct usb_serial_port *port, int on)
{
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        u8 control;

        spin_lock_irqsave(&priv->lock, flags);
        if (on)
                priv->line_control = MCR_CONTROL_LINE_DTR
                                                | MCR_CONTROL_LINE_RTS;
        else
                priv->line_control &= ~ (MCR_CONTROL_LINE_DTR
                                                | MCR_CONTROL_LINE_RTS);
        control = priv->line_control;
        spin_unlock_irqrestore(&priv->lock, flags);
        spcp8x5_set_ctrlLine(port->serial->dev, control , priv->type);
}

/* close the serial port. We should wait for data sending to device 1st and
 * then kill all urb. */
static void spcp8x5_close(struct usb_serial_port *port)
{
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        int result;

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

        spin_lock_irqsave(&priv->lock, flags);
        /* clear out any remaining data in the buffer */
        clear_ringbuf(priv->buf);
        spin_unlock_irqrestore(&priv->lock, flags);

        /* kill urb */
        if (port->write_urb != NULL) {
                result = usb_unlink_urb(port->write_urb);
                if (result)
                        dev_dbg(&port->dev,
                                "usb_unlink_urb(write_urb) = %d\n", result);
        }
        result = usb_unlink_urb(port->read_urb);
        if (result)
                dev_dbg(&port->dev, "usb_unlink_urb(read_urb) = %d\n", result);
}

static void spcp8x5_init_termios(struct tty_struct *tty)
{
        /* for the 1st time call this function */
        *(tty->termios) = tty_std_termios;
        tty->termios->c_cflag = B115200 | CS8 | CREAD | HUPCL | CLOCAL;
        tty->termios->c_ispeed = 115200;
        tty->termios->c_ospeed = 115200;
}

/* set the serial param for transfer. we should check if we really need to
 * transfer. if we set flow control we should do this too. */
static void spcp8x5_set_termios(struct tty_struct *tty,
                struct usb_serial_port *port, struct ktermios *old_termios)
{
        struct usb_serial *serial = port->serial;
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        unsigned int cflag = tty->termios->c_cflag;
        unsigned int old_cflag = old_termios->c_cflag;
        unsigned short uartdata;
        unsigned char buf[2] = {0, 0};
        int baud;
        int i;
        u8 control;


        /* check that they really want us to change something */
        if (!tty_termios_hw_change(tty->termios, old_termios))
                return;

        /* set DTR/RTS active */
        spin_lock_irqsave(&priv->lock, flags);
        control = priv->line_control;
        if ((old_cflag & CBAUD) == B0) {
                priv->line_control |= MCR_DTR;
                if (!(old_cflag & CRTSCTS))
                        priv->line_control |= MCR_RTS;
        }
        if (control != priv->line_control) {
                control = priv->line_control;
                spin_unlock_irqrestore(&priv->lock, flags);
                spcp8x5_set_ctrlLine(serial->dev, control , priv->type);
        } else {
                spin_unlock_irqrestore(&priv->lock, flags);
        }

        /* Set Baud Rate */
        baud = tty_get_baud_rate(tty);
        switch (baud) {
        case 300:       buf[0] = 0x00;  break;
        case 600:       buf[0] = 0x01;  break;
        case 1200:      buf[0] = 0x02;  break;
        case 2400:      buf[0] = 0x03;  break;
        case 4800:      buf[0] = 0x04;  break;
        case 9600:      buf[0] = 0x05;  break;
        case 19200:     buf[0] = 0x07;  break;
        case 38400:     buf[0] = 0x09;  break;
        case 57600:     buf[0] = 0x0a;  break;
        case 115200:    buf[0] = 0x0b;  break;
        case 230400:    buf[0] = 0x0c;  break;
        case 460800:    buf[0] = 0x0d;  break;
        case 921600:    buf[0] = 0x0e;  break;
/*      case 1200000:   buf[0] = 0x0f;  break; */
/*      case 2400000:   buf[0] = 0x10;  break; */
        case 3000000:   buf[0] = 0x11;  break;
/*      case 6000000:   buf[0] = 0x12;  break; */
        case 0:
        case 1000000:
                        buf[0] = 0x0b;  break;
        default:
                dev_err(&port->dev, "spcp825 driver does not support the "
                        "baudrate requested, using default of 9600.\n");
        }

        /* Set Data Length : 00:5bit, 01:6bit, 10:7bit, 11:8bit */
        if (cflag & CSIZE) {
                switch (cflag & CSIZE) {
                case CS5:
                        buf[1] |= SET_UART_FORMAT_SIZE_5;
                        break;
                case CS6:
                        buf[1] |= SET_UART_FORMAT_SIZE_6;
                        break;
                case CS7:
                        buf[1] |= SET_UART_FORMAT_SIZE_7;
                        break;
                default:
                case CS8:
                        buf[1] |= SET_UART_FORMAT_SIZE_8;
                        break;
                }
        }

        /* Set Stop bit2 : 0:1bit 1:2bit */
        buf[1] |= (cflag & CSTOPB) ? SET_UART_FORMAT_STOP_2 :
                                     SET_UART_FORMAT_STOP_1;

        /* Set Parity bit3-4 01:Odd 11:Even */
        if (cflag & PARENB) {
                buf[1] |= (cflag & PARODD) ?
                SET_UART_FORMAT_PAR_ODD : SET_UART_FORMAT_PAR_EVEN ;
        } else
                buf[1] |= SET_UART_FORMAT_PAR_NONE;

        uartdata = buf[0] | buf[1]<<8;

        i = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
                            SET_UART_FORMAT_TYPE, SET_UART_FORMAT,
                            uartdata, 0, NULL, 0, 100);
        if (i < 0)
                dev_err(&port->dev, "Set UART format %#x failed (error = %d)\n",
                        uartdata, i);
        dbg("0x21:0x40:0:0  %d\n", i);

        if (cflag & CRTSCTS) {
                /* enable hardware flow control */
                spcp8x5_set_workMode(serial->dev, 0x000a,
                                     SET_WORKING_MODE_U2C, priv->type);
        }
        return;
}

/* open the serial port. do some usb system call. set termios and get the line
 * status of the device. then submit the read urb */
static int spcp8x5_open(struct tty_struct *tty, struct usb_serial_port *port)
{
        struct ktermios tmp_termios;
        struct usb_serial *serial = port->serial;
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        int ret;
        unsigned long flags;
        u8 status = 0x30;
        /* status 0x30 means DSR and CTS = 1 other CDC RI and delta = 0 */

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

        usb_clear_halt(serial->dev, port->write_urb->pipe);
        usb_clear_halt(serial->dev, port->read_urb->pipe);

        ret = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
                              0x09, 0x00,
                              0x01, 0x00, NULL, 0x00, 100);
        if (ret)
                return ret;

        spcp8x5_set_ctrlLine(serial->dev, priv->line_control , priv->type);

        /* Setup termios */
        if (tty)
                spcp8x5_set_termios(tty, port, &tmp_termios);

        spcp8x5_get_msr(serial->dev, &status, priv->type);

        /* may be we should update uart status here but now we did not do */
        spin_lock_irqsave(&priv->lock, flags);
        priv->line_status = status & 0xf0 ;
        spin_unlock_irqrestore(&priv->lock, flags);

        dbg("%s - submitting read urb", __func__);
        port->read_urb->dev = serial->dev;
        ret = usb_submit_urb(port->read_urb, GFP_KERNEL);
        if (ret) {
                spcp8x5_close(port);
                return -EPROTO;
        }
        port->port.drain_delay = 256;
        return 0;
}

/* bulk read call back function. check the status of the urb. if transfer
 * failed return. then update the status and the tty send data to tty subsys.
 * submit urb again.
 */
static void spcp8x5_read_bulk_callback(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        struct tty_struct *tty;
        unsigned char *data = urb->transfer_buffer;
        unsigned long flags;
        int i;
        int result = urb->status;
        u8 status;
        char tty_flag;

        dev_dbg(&port->dev, "start, result = %d, urb->actual_length = %d\n,",
                result, urb->actual_length);

        /* check the urb status */
        if (result) {
                if (!port->port.count)
                        return;
                if (result == -EPROTO) {
                        /* spcp8x5 mysteriously fails with -EPROTO */
                        /* reschedule the read */
                        urb->dev = port->serial->dev;
                        result = usb_submit_urb(urb , GFP_ATOMIC);
                        if (result)
                                dev_dbg(&port->dev,
                                        "failed submitting read urb %d\n",
                                        result);
                        return;
                }
                dev_dbg(&port->dev, "unable to handle the error, exiting.\n");
                return;
        }

        /* get tty_flag from status */
        tty_flag = TTY_NORMAL;

        spin_lock_irqsave(&priv->lock, flags);
        status = priv->line_status;
        priv->line_status &= ~UART_STATE_TRANSIENT_MASK;
        spin_unlock_irqrestore(&priv->lock, flags);
        /* wake up the wait for termios */
        wake_up_interruptible(&priv->delta_msr_wait);

        /* break takes precedence over parity, which takes precedence over
         * framing errors */
        if (status & UART_BREAK_ERROR)
                tty_flag = TTY_BREAK;
        else if (status & UART_PARITY_ERROR)
                tty_flag = TTY_PARITY;
        else if (status & UART_FRAME_ERROR)
                tty_flag = TTY_FRAME;
        dev_dbg(&port->dev, "tty_flag = %d\n", tty_flag);

        tty = tty_port_tty_get(&port->port);
        if (tty && urb->actual_length) {
                tty_buffer_request_room(tty, urb->actual_length + 1);
                /* overrun is special, not associated with a char */
                if (status & UART_OVERRUN_ERROR)
                        tty_insert_flip_char(tty, 0, TTY_OVERRUN);
                for (i = 0; i < urb->actual_length; ++i)
                        tty_insert_flip_char(tty, data[i], tty_flag);
                tty_flip_buffer_push(tty);
        }
        tty_kref_put(tty);

        /* Schedule the next read _if_ we are still open */
        if (port->port.count) {
                urb->dev = port->serial->dev;
                result = usb_submit_urb(urb , GFP_ATOMIC);
                if (result)
                        dev_dbg(&port->dev, "failed submitting read urb %d\n",
                                result);
        }

        return;
}

/* get data from ring buffer and then write to usb bus */
static void spcp8x5_send(struct usb_serial_port *port)
{
        int count, result;
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;

        spin_lock_irqsave(&priv->lock, flags);

        if (priv->write_urb_in_use) {
                dev_dbg(&port->dev, "write urb still used\n");
                spin_unlock_irqrestore(&priv->lock, flags);
                return;
        }

        /* send the 1st urb for writting */
        memset(port->write_urb->transfer_buffer , 0x00 , port->bulk_out_size);
        count = get_ringbuf(priv->buf, port->write_urb->transfer_buffer,
                port->bulk_out_size);

        if (count == 0) {
                spin_unlock_irqrestore(&priv->lock, flags);
                return;
        }

        /* update the urb status */
        priv->write_urb_in_use = 1;

        spin_unlock_irqrestore(&priv->lock, flags);

        port->write_urb->transfer_buffer_length = count;
        port->write_urb->dev = port->serial->dev;

        result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
        if (result) {
                dev_dbg(&port->dev, "failed submitting write urb, error %d\n",
                        result);
                priv->write_urb_in_use = 0;
                /* TODO: reschedule spcp8x5_send */
        }


        schedule_work(&port->work);
}

/* this is the call back function for write urb. NOTE we should not sleep in
 * this routine. check the urb return code and then submit the write urb again
 * to hold the write loop */
static void spcp8x5_write_bulk_callback(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        int result;
        int status = urb->status;

        switch (status) {
        case 0:
                /* success */
                break;
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
                /* this urb is terminated, clean up */
                dev_dbg(&port->dev, "urb shutting down with status: %d\n",
                        status);
                priv->write_urb_in_use = 0;
                return;
        default:
                /* error in the urb, so we have to resubmit it */
                dbg("%s - Overflow in write", __func__);
                dbg("%s - nonzero write bulk status received: %d",
                        __func__, status);
                port->write_urb->transfer_buffer_length = 1;
                port->write_urb->dev = port->serial->dev;
                result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
                if (result)
                        dev_dbg(&port->dev,
                                "failed resubmitting write urb %d\n", result);
                else
                        return;
        }

        priv->write_urb_in_use = 0;

        /* send any buffered data */
        spcp8x5_send(port);
}

/* write data to ring buffer. and then start the write transfer */
static int spcp8x5_write(struct tty_struct *tty, struct usb_serial_port *port,
                         const unsigned char *buf, int count)
{
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;

        dev_dbg(&port->dev, "%d bytes\n", count);

        if (!count)
                return count;

        spin_lock_irqsave(&priv->lock, flags);
        count = put_ringbuf(priv->buf, buf, count);
        spin_unlock_irqrestore(&priv->lock, flags);

        spcp8x5_send(port);

        return count;
}

static int spcp8x5_wait_modem_info(struct usb_serial_port *port,
                                   unsigned int arg)
{
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        unsigned int prevstatus;
        unsigned int status;
        unsigned int changed;

        spin_lock_irqsave(&priv->lock, flags);
        prevstatus = priv->line_status;
        spin_unlock_irqrestore(&priv->lock, flags);

        while (1) {
                /* wake up in bulk read */
                interruptible_sleep_on(&priv->delta_msr_wait);

                /* see if a signal did it */
                if (signal_pending(current))
                        return -ERESTARTSYS;

                spin_lock_irqsave(&priv->lock, flags);
                status = priv->line_status;
                spin_unlock_irqrestore(&priv->lock, flags);

                changed = prevstatus^status;

                if (((arg & TIOCM_RNG) && (changed & MSR_STATUS_LINE_RI)) ||
                    ((arg & TIOCM_DSR) && (changed & MSR_STATUS_LINE_DSR)) ||
                    ((arg & TIOCM_CD)  && (changed & MSR_STATUS_LINE_DCD)) ||
                    ((arg & TIOCM_CTS) && (changed & MSR_STATUS_LINE_CTS)))
                        return 0;

                prevstatus = status;
        }
        /* NOTREACHED */
        return 0;
}

static int spcp8x5_ioctl(struct tty_struct *tty, struct file *file,
                         unsigned int cmd, unsigned long arg)
{
        struct usb_serial_port *port = tty->driver_data;
        dbg("%s (%d) cmd = 0x%04x", __func__, port->number, cmd);

        switch (cmd) {
        case TIOCMIWAIT:
                dbg("%s (%d) TIOCMIWAIT", __func__,  port->number);
                return spcp8x5_wait_modem_info(port, arg);

        default:
                dbg("%s not supported = 0x%04x", __func__, cmd);
                break;
        }

        return -ENOIOCTLCMD;
}

static int spcp8x5_tiocmset(struct tty_struct *tty, struct file *file,
                            unsigned int set, unsigned int clear)
{
        struct usb_serial_port *port = tty->driver_data;
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        u8 control;

        spin_lock_irqsave(&priv->lock, flags);
        if (set & TIOCM_RTS)
                priv->line_control |= MCR_RTS;
        if (set & TIOCM_DTR)
                priv->line_control |= MCR_DTR;
        if (clear & TIOCM_RTS)
                priv->line_control &= ~MCR_RTS;
        if (clear & TIOCM_DTR)
                priv->line_control &= ~MCR_DTR;
        control = priv->line_control;
        spin_unlock_irqrestore(&priv->lock, flags);

        return spcp8x5_set_ctrlLine(port->serial->dev, control , priv->type);
}

static int spcp8x5_tiocmget(struct tty_struct *tty, struct file *file)
{
        struct usb_serial_port *port = tty->driver_data;
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        unsigned int mcr;
        unsigned int status;
        unsigned int result;

        spin_lock_irqsave(&priv->lock, flags);
        mcr = priv->line_control;
        status = priv->line_status;
        spin_unlock_irqrestore(&priv->lock, flags);

        result = ((mcr & MCR_DTR)                       ? TIOCM_DTR : 0)
                  | ((mcr & MCR_RTS)                    ? TIOCM_RTS : 0)
                  | ((status & MSR_STATUS_LINE_CTS)     ? TIOCM_CTS : 0)
                  | ((status & MSR_STATUS_LINE_DSR)     ? TIOCM_DSR : 0)
                  | ((status & MSR_STATUS_LINE_RI)      ? TIOCM_RI  : 0)
                  | ((status & MSR_STATUS_LINE_DCD)     ? TIOCM_CD  : 0);

        return result;
}

/* get the avail space room in ring buffer */
static int spcp8x5_write_room(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        int room = 0;
        unsigned long flags;

        spin_lock_irqsave(&priv->lock, flags);
        room = ringbuf_avail_space(priv->buf);
        spin_unlock_irqrestore(&priv->lock, flags);

        return room;
}

/* get the number of avail data in write ring buffer */
static int spcp8x5_chars_in_buffer(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct spcp8x5_private *priv = usb_get_serial_port_data(port);
        int chars = 0;
        unsigned long flags;

        spin_lock_irqsave(&priv->lock, flags);
        chars = ringbuf_avail_data(priv->buf);
        spin_unlock_irqrestore(&priv->lock, flags);

        return chars;
}

/* All of the device info needed for the spcp8x5 SIO serial converter */
static struct usb_serial_driver spcp8x5_device = {
        .driver = {
                .owner =        THIS_MODULE,
                .name =         "SPCP8x5",
        },

        .id_table               = id_table,
        .num_ports              = 1,
        .open                   = spcp8x5_open,
        .close                  = spcp8x5_close,
        .dtr_rts                = spcp8x5_dtr_rts,
        .carrier_raised         = spcp8x5_carrier_raised,
        .write                  = spcp8x5_write,
        .set_termios            = spcp8x5_set_termios,
        .init_termios           = spcp8x5_init_termios,
        .ioctl                  = spcp8x5_ioctl,
        .tiocmget               = spcp8x5_tiocmget,
        .tiocmset               = spcp8x5_tiocmset,
        .write_room             = spcp8x5_write_room,
        .read_bulk_callback     = spcp8x5_read_bulk_callback,
        .write_bulk_callback    = spcp8x5_write_bulk_callback,
        .chars_in_buffer        = spcp8x5_chars_in_buffer,
        .attach                 = spcp8x5_startup,
        .release                = spcp8x5_release,
};

static int __init spcp8x5_init(void)
{
        int retval;
        retval = usb_serial_register(&spcp8x5_device);
        if (retval)
                goto failed_usb_serial_register;
        retval = usb_register(&spcp8x5_driver);
        if (retval)
                goto failed_usb_register;
        printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":"
               DRIVER_DESC "\n");
        return 0;
failed_usb_register:
        usb_serial_deregister(&spcp8x5_device);
failed_usb_serial_register:
        return retval;
}

static void __exit spcp8x5_exit(void)
{
        usb_deregister(&spcp8x5_driver);
        usb_serial_deregister(&spcp8x5_device);
}

module_init(spcp8x5_init);
module_exit(spcp8x5_exit);

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

module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug enabled or not");