/*
 * USB Cypress M8 driver
 *
 *      Copyright (C) 2004
 *          Lonnie Mendez (dignome@gmail.com)
 *      Copyright (C) 2003,2004
 *          Neil Whelchel (koyama@firstlight.net)
 *
 *      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.
 *
 * See Documentation/usb/usb-serial.txt for more information on using this
 * driver
 *
 * See http://geocities.com/i0xox0i for information on this driver and the
 * earthmate usb device.
 *
 *  Lonnie Mendez <dignome@gmail.com>
 *  4-29-2005
 *      Fixed problem where setting or retreiving the serial config would fail
 *      with EPIPE.  Removed CRTS toggling so the driver behaves more like
 *      other usbserial adapters.  Issued new interval of 1ms instead of the
 *      default 10ms.  As a result, transfer speed has been substantially
 *      increased from avg. 850bps to avg. 3300bps.  initial termios has also
 *      been modified.  Cleaned up code and formatting issues so it is more
 *      readable.  Replaced the C++ style comments.
 *
 *  Lonnie Mendez <dignome@gmail.com>
 *  12-15-2004
 *      Incorporated write buffering from pl2303 driver.  Fixed bug with line
 *      handling so both lines are raised in cypress_open. (was dropping rts)
 *      Various code cleanups made as well along with other misc bug fixes.
 *
 *  Lonnie Mendez <dignome@gmail.com>
 *  04-10-2004
 *      Driver modified to support dynamic line settings.  Various improvments
 *      and features.
 *
 *  Neil Whelchel
 *  10-2003
 *      Driver first released.
 *
 */

/* Thanks to Neil Whelchel for writing the first cypress m8 implementation
   for linux. */
/* Thanks to cypress for providing references for the hid reports. */
/* Thanks to Jiang Zhang for providing links and for general help. */
/* Code originates and was built up from ftdi_sio, belkin, pl2303 and others.*/


#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/moduleparam.h>
#include <linux/spinlock.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/serial.h>
#include <linux/delay.h>
#include <linux/uaccess.h>

#include "cypress_m8.h"


#ifdef CONFIG_USB_SERIAL_DEBUG
        static int debug = 1;
#else
        static int debug;
#endif
static int stats;
static int interval;

/*
 * Version Information
 */
#define DRIVER_VERSION "v1.09"
#define DRIVER_AUTHOR "Lonnie Mendez <dignome@gmail.com>, Neil Whelchel <koyama@firstlight.net>"
#define DRIVER_DESC "Cypress USB to Serial Driver"

/* write buffer size defines */
#define CYPRESS_BUF_SIZE        1024
#define CYPRESS_CLOSING_WAIT    (30*HZ)

static struct usb_device_id id_table_earthmate [] = {
        { USB_DEVICE(VENDOR_ID_DELORME, PRODUCT_ID_EARTHMATEUSB) },
        { USB_DEVICE(VENDOR_ID_DELORME, PRODUCT_ID_EARTHMATEUSB_LT20) },
        { }                                             /* Terminating entry */
};

static struct usb_device_id id_table_cyphidcomrs232 [] = {
        { USB_DEVICE(VENDOR_ID_CYPRESS, PRODUCT_ID_CYPHIDCOM) },
        { USB_DEVICE(VENDOR_ID_POWERCOM, PRODUCT_ID_UPS) },
        { }                                             /* Terminating entry */
};

static struct usb_device_id id_table_nokiaca42v2 [] = {
        { USB_DEVICE(VENDOR_ID_DAZZLE, PRODUCT_ID_CA42) },
        { }                                             /* Terminating entry */
};

static struct usb_device_id id_table_combined [] = {
        { USB_DEVICE(VENDOR_ID_DELORME, PRODUCT_ID_EARTHMATEUSB) },
        { USB_DEVICE(VENDOR_ID_DELORME, PRODUCT_ID_EARTHMATEUSB_LT20) },
        { USB_DEVICE(VENDOR_ID_CYPRESS, PRODUCT_ID_CYPHIDCOM) },
        { USB_DEVICE(VENDOR_ID_POWERCOM, PRODUCT_ID_UPS) },
        { USB_DEVICE(VENDOR_ID_DAZZLE, PRODUCT_ID_CA42) },
        { }                                             /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, id_table_combined);

static struct usb_driver cypress_driver = {
        .name =         "cypress",
        .probe =        usb_serial_probe,
        .disconnect =   usb_serial_disconnect,
        .id_table =     id_table_combined,
        .no_dynamic_id =        1,
};

enum packet_format {
        packet_format_1,  /* b0:status, b1:payload count */
        packet_format_2   /* b0[7:3]:status, b0[2:0]:payload count */
};

struct cypress_private {
        spinlock_t lock;                   /* private lock */
        int chiptype;                      /* identifier of device, for quirks/etc */
        int bytes_in;                      /* used for statistics */
        int bytes_out;                     /* used for statistics */
        int cmd_count;                     /* used for statistics */
        int cmd_ctrl;                      /* always set this to 1 before issuing a command */
        struct cypress_buf *buf;           /* write buffer */
        int write_urb_in_use;              /* write urb in use indicator */
        int write_urb_interval;            /* interval to use for write urb */
        int read_urb_interval;             /* interval to use for read urb */
        int comm_is_ok;                    /* true if communication is (still) ok */
        int termios_initialized;
        __u8 line_control;                 /* holds dtr / rts value */
        __u8 current_status;               /* received from last read - info on dsr,cts,cd,ri,etc */
        __u8 current_config;               /* stores the current configuration byte */
        __u8 rx_flags;                     /* throttling - used from whiteheat/ftdi_sio */
        enum packet_format pkt_fmt;        /* format to use for packet send / receive */
        int get_cfg_unsafe;                /* If true, the CYPRESS_GET_CONFIG is unsafe */
        int baud_rate;                     /* stores current baud rate in
                                              integer form */
        int isthrottled;                   /* if throttled, discard reads */
        wait_queue_head_t delta_msr_wait;  /* used for TIOCMIWAIT */
        char prev_status, diff_status;     /* used for TIOCMIWAIT */
        /* we pass a pointer to this as the arguement sent to
           cypress_set_termios old_termios */
        struct ktermios tmp_termios;       /* stores the old termios settings */
};

/* write buffer structure */
struct cypress_buf {
        unsigned int    buf_size;
        char            *buf_buf;
        char            *buf_get;
        char            *buf_put;
};

/* function prototypes for the Cypress USB to serial device */
static int  cypress_earthmate_startup(struct usb_serial *serial);
static int  cypress_hidcom_startup(struct usb_serial *serial);
static int  cypress_ca42v2_startup(struct usb_serial *serial);
static void cypress_release(struct usb_serial *serial);
static int  cypress_open(struct tty_struct *tty, struct usb_serial_port *port);
static void cypress_close(struct usb_serial_port *port);
static void cypress_dtr_rts(struct usb_serial_port *port, int on);
static int  cypress_write(struct tty_struct *tty, struct usb_serial_port *port,
                        const unsigned char *buf, int count);
static void cypress_send(struct usb_serial_port *port);
static int  cypress_write_room(struct tty_struct *tty);
static int  cypress_ioctl(struct tty_struct *tty, struct file *file,
                        unsigned int cmd, unsigned long arg);
static void cypress_set_termios(struct tty_struct *tty,
                        struct usb_serial_port *port, struct ktermios *old);
static int  cypress_tiocmget(struct tty_struct *tty, struct file *file);
static int  cypress_tiocmset(struct tty_struct *tty, struct file *file,
                        unsigned int set, unsigned int clear);
static int  cypress_chars_in_buffer(struct tty_struct *tty);
static void cypress_throttle(struct tty_struct *tty);
static void cypress_unthrottle(struct tty_struct *tty);
static void cypress_set_dead(struct usb_serial_port *port);
static void cypress_read_int_callback(struct urb *urb);
static void cypress_write_int_callback(struct urb *urb);
/* write buffer functions */
static struct cypress_buf *cypress_buf_alloc(unsigned int size);
static void cypress_buf_free(struct cypress_buf *cb);
static void cypress_buf_clear(struct cypress_buf *cb);
static unsigned int cypress_buf_data_avail(struct cypress_buf *cb);
static unsigned int cypress_buf_space_avail(struct cypress_buf *cb);
static unsigned int cypress_buf_put(struct cypress_buf *cb,
                                        const char *buf, unsigned int count);
static unsigned int cypress_buf_get(struct cypress_buf *cb,
                                        char *buf, unsigned int count);


static struct usb_serial_driver cypress_earthmate_device = {
        .driver = {
                .owner =                THIS_MODULE,
                .name =                 "earthmate",
        },
        .description =                  "DeLorme Earthmate USB",
        .usb_driver =                   &cypress_driver,
        .id_table =                     id_table_earthmate,
        .num_ports =                    1,
        .attach =                       cypress_earthmate_startup,
        .release =                      cypress_release,
        .open =                         cypress_open,
        .close =                        cypress_close,
        .dtr_rts =                      cypress_dtr_rts,
        .write =                        cypress_write,
        .write_room =                   cypress_write_room,
        .ioctl =                        cypress_ioctl,
        .set_termios =                  cypress_set_termios,
        .tiocmget =                     cypress_tiocmget,
        .tiocmset =                     cypress_tiocmset,
        .chars_in_buffer =              cypress_chars_in_buffer,
        .throttle =                     cypress_throttle,
        .unthrottle =                   cypress_unthrottle,
        .read_int_callback =            cypress_read_int_callback,
        .write_int_callback =           cypress_write_int_callback,
};

static struct usb_serial_driver cypress_hidcom_device = {
        .driver = {
                .owner =                THIS_MODULE,
                .name =                 "cyphidcom",
        },
        .description =                  "HID->COM RS232 Adapter",
        .usb_driver =                   &cypress_driver,
        .id_table =                     id_table_cyphidcomrs232,
        .num_ports =                    1,
        .attach =                       cypress_hidcom_startup,
        .release =                      cypress_release,
        .open =                         cypress_open,
        .close =                        cypress_close,
        .dtr_rts =                      cypress_dtr_rts,
        .write =                        cypress_write,
        .write_room =                   cypress_write_room,
        .ioctl =                        cypress_ioctl,
        .set_termios =                  cypress_set_termios,
        .tiocmget =                     cypress_tiocmget,
        .tiocmset =                     cypress_tiocmset,
        .chars_in_buffer =              cypress_chars_in_buffer,
        .throttle =                     cypress_throttle,
        .unthrottle =                   cypress_unthrottle,
        .read_int_callback =            cypress_read_int_callback,
        .write_int_callback =           cypress_write_int_callback,
};

static struct usb_serial_driver cypress_ca42v2_device = {
        .driver = {
                .owner =                THIS_MODULE,
                .name =                 "nokiaca42v2",
        },
        .description =                  "Nokia CA-42 V2 Adapter",
        .usb_driver =                   &cypress_driver,
        .id_table =                     id_table_nokiaca42v2,
        .num_ports =                    1,
        .attach =                       cypress_ca42v2_startup,
        .release =                      cypress_release,
        .open =                         cypress_open,
        .close =                        cypress_close,
        .dtr_rts =                      cypress_dtr_rts,
        .write =                        cypress_write,
        .write_room =                   cypress_write_room,
        .ioctl =                        cypress_ioctl,
        .set_termios =                  cypress_set_termios,
        .tiocmget =                     cypress_tiocmget,
        .tiocmset =                     cypress_tiocmset,
        .chars_in_buffer =              cypress_chars_in_buffer,
        .throttle =                     cypress_throttle,
        .unthrottle =                   cypress_unthrottle,
        .read_int_callback =            cypress_read_int_callback,
        .write_int_callback =           cypress_write_int_callback,
};

/*****************************************************************************
 * Cypress serial helper functions
 *****************************************************************************/


static int analyze_baud_rate(struct usb_serial_port *port, speed_t new_rate)
{
        struct cypress_private *priv;
        priv = usb_get_serial_port_data(port);

        /*
         * The general purpose firmware for the Cypress M8 allows for
         * a maximum speed of 57600bps (I have no idea whether DeLorme
         * chose to use the general purpose firmware or not), if you
         * need to modify this speed setting for your own project
         * please add your own chiptype and modify the code likewise.
         * The Cypress HID->COM device will work successfully up to
         * 115200bps (but the actual throughput is around 3kBps).
         */
        if (port->serial->dev->speed == USB_SPEED_LOW) {
                /*
                 * Mike Isely <isely@pobox.com> 2-Feb-2008: The
                 * Cypress app note that describes this mechanism
                 * states the the low-speed part can't handle more
                 * than 800 bytes/sec, in which case 4800 baud is the
                 * safest speed for a part like that.
                 */
                if (new_rate > 4800) {
                        dbg("%s - failed setting baud rate, device incapable "
                            "speed %d", __func__, new_rate);
                        return -1;
                }
        }
        switch (priv->chiptype) {
        case CT_EARTHMATE:
                if (new_rate <= 600) {
                        /* 300 and 600 baud rates are supported under
                         * the generic firmware, but are not used with
                         * NMEA and SiRF protocols */
                        dbg("%s - failed setting baud rate, unsupported speed "
                            "of %d on Earthmate GPS", __func__, new_rate);
                        return -1;
                }
                break;
        default:
                break;
        }
        return new_rate;
}


/* This function can either set or retrieve the current serial line settings */
static int cypress_serial_control(struct tty_struct *tty,
        struct usb_serial_port *port, speed_t baud_rate, int data_bits,
        int stop_bits, int parity_enable, int parity_type, int reset,
        int cypress_request_type)
{
        int new_baudrate = 0, retval = 0, tries = 0;
        struct cypress_private *priv;
        __u8 feature_buffer[5];
        unsigned long flags;

        dbg("%s", __func__);

        priv = usb_get_serial_port_data(port);

        if (!priv->comm_is_ok)
                return -ENODEV;

        switch (cypress_request_type) {
        case CYPRESS_SET_CONFIG:
                new_baudrate = priv->baud_rate;
                /* 0 means 'Hang up' so doesn't change the true bit rate */
                if (baud_rate == 0)
                        new_baudrate = priv->baud_rate;
                /* Change of speed ? */
                else if (baud_rate != priv->baud_rate) {
                        dbg("%s - baud rate is changing", __func__);
                        retval = analyze_baud_rate(port, baud_rate);
                        if (retval >=  0) {
                                new_baudrate = retval;
                                dbg("%s - New baud rate set to %d",
                                    __func__, new_baudrate);
                        }
                }
                dbg("%s - baud rate is being sent as %d",
                                        __func__, new_baudrate);

                memset(feature_buffer, 0, sizeof(feature_buffer));
                /* fill the feature_buffer with new configuration */
                *((u_int32_t *)feature_buffer) = new_baudrate;
                feature_buffer[4] |= data_bits;   /* assign data bits in 2 bit space ( max 3 ) */
                /* 1 bit gap */
                feature_buffer[4] |= (stop_bits << 3);   /* assign stop bits in 1 bit space */
                feature_buffer[4] |= (parity_enable << 4);   /* assign parity flag in 1 bit space */
                feature_buffer[4] |= (parity_type << 5);   /* assign parity type in 1 bit space */
                /* 1 bit gap */
                feature_buffer[4] |= (reset << 7);   /* assign reset at end of byte, 1 bit space */

                dbg("%s - device is being sent this feature report:",
                                                                __func__);
                dbg("%s - %02X - %02X - %02X - %02X - %02X", __func__,
                        feature_buffer[0], feature_buffer[1],
                        feature_buffer[2], feature_buffer[3],
                        feature_buffer[4]);

                do {
                        retval = usb_control_msg(port->serial->dev,
                                        usb_sndctrlpipe(port->serial->dev, 0),
                                        HID_REQ_SET_REPORT,
                                        USB_DIR_OUT | USB_RECIP_INTERFACE | USB_TYPE_CLASS,
                                        0x0300, 0, feature_buffer,
                                        sizeof(feature_buffer), 500);

                        if (tries++ >= 3)
                                break;

                } while (retval != sizeof(feature_buffer) &&
                         retval != -ENODEV);

                if (retval != sizeof(feature_buffer)) {
                        dev_err(&port->dev, "%s - failed sending serial "
                                "line settings - %d\n", __func__, retval);
                        cypress_set_dead(port);
                } else {
                        spin_lock_irqsave(&priv->lock, flags);
                        priv->baud_rate = new_baudrate;
                        priv->current_config = feature_buffer[4];
                        spin_unlock_irqrestore(&priv->lock, flags);
                        /* If we asked for a speed change encode it */
                        if (baud_rate)
                                tty_encode_baud_rate(tty,
                                        new_baudrate, new_baudrate);
                }
        break;
        case CYPRESS_GET_CONFIG:
                if (priv->get_cfg_unsafe) {
                        /* Not implemented for this device,
                           and if we try to do it we're likely
                           to crash the hardware. */
                        return -ENOTTY;
                }
                dbg("%s - retreiving serial line settings", __func__);
                /* set initial values in feature buffer */
                memset(feature_buffer, 0, sizeof(feature_buffer));

                do {
                        retval = usb_control_msg(port->serial->dev,
                                        usb_rcvctrlpipe(port->serial->dev, 0),
                                        HID_REQ_GET_REPORT,
                                        USB_DIR_IN | USB_RECIP_INTERFACE | USB_TYPE_CLASS,
                                        0x0300, 0, feature_buffer,
                                        sizeof(feature_buffer), 500);

                        if (tries++ >= 3)
                                break;
                } while (retval != sizeof(feature_buffer)
                                                && retval != -ENODEV);

                if (retval != sizeof(feature_buffer)) {
                        dev_err(&port->dev, "%s - failed to retrieve serial "
                                "line settings - %d\n", __func__, retval);
                        cypress_set_dead(port);
                        return retval;
                } else {
                        spin_lock_irqsave(&priv->lock, flags);
                        /* store the config in one byte, and later
                           use bit masks to check values */
                        priv->current_config = feature_buffer[4];
                        priv->baud_rate = *((u_int32_t *)feature_buffer);
                        spin_unlock_irqrestore(&priv->lock, flags);
                }
        }
        spin_lock_irqsave(&priv->lock, flags);
        ++priv->cmd_count;
        spin_unlock_irqrestore(&priv->lock, flags);

        return retval;
} /* cypress_serial_control */


static void cypress_set_dead(struct usb_serial_port *port)
{
        struct cypress_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;

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

        dev_err(&port->dev, "cypress_m8 suspending failing port %d - "
                "interval might be too short\n", port->number);
}


/*****************************************************************************
 * Cypress serial driver functions
 *****************************************************************************/


static int generic_startup(struct usb_serial *serial)
{
        struct cypress_private *priv;
        struct usb_serial_port *port = serial->port[0];

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

        priv = kzalloc(sizeof(struct cypress_private), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->comm_is_ok = !0;
        spin_lock_init(&priv->lock);
        priv->buf = cypress_buf_alloc(CYPRESS_BUF_SIZE);
        if (priv->buf == NULL) {
                kfree(priv);
                return -ENOMEM;
        }
        init_waitqueue_head(&priv->delta_msr_wait);

        usb_reset_configuration(serial->dev);

        priv->cmd_ctrl = 0;
        priv->line_control = 0;
        priv->termios_initialized = 0;
        priv->rx_flags = 0;
        /* Default packet format setting is determined by packet size.
           Anything with a size larger then 9 must have a separate
           count field since the 3 bit count field is otherwise too
           small.  Otherwise we can use the slightly more compact
           format.  This is in accordance with the cypress_m8 serial
           converter app note. */
        if (port->interrupt_out_size > 9)
                priv->pkt_fmt = packet_format_1;
        else
                priv->pkt_fmt = packet_format_2;

        if (interval > 0) {
                priv->write_urb_interval = interval;
                priv->read_urb_interval = interval;
                dbg("%s - port %d read & write intervals forced to %d",
                    __func__, port->number, interval);
        } else {
                priv->write_urb_interval = port->interrupt_out_urb->interval;
                priv->read_urb_interval = port->interrupt_in_urb->interval;
                dbg("%s - port %d intervals: read=%d write=%d",
                    __func__, port->number,
                    priv->read_urb_interval, priv->write_urb_interval);
        }
        usb_set_serial_port_data(port, priv);

        return 0;
}


static int cypress_earthmate_startup(struct usb_serial *serial)
{
        struct cypress_private *priv;
        struct usb_serial_port *port = serial->port[0];

        dbg("%s", __func__);

        if (generic_startup(serial)) {
                dbg("%s - Failed setting up port %d", __func__,
                                port->number);
                return 1;
        }

        priv = usb_get_serial_port_data(port);
        priv->chiptype = CT_EARTHMATE;
        /* All Earthmate devices use the separated-count packet
           format!  Idiotic. */
        priv->pkt_fmt = packet_format_1;
        if (serial->dev->descriptor.idProduct !=
                                cpu_to_le16(PRODUCT_ID_EARTHMATEUSB)) {
                /* The old original USB Earthmate seemed able to
                   handle GET_CONFIG requests; everything they've
                   produced since that time crashes if this command is
                   attempted :-( */
                dbg("%s - Marking this device as unsafe for GET_CONFIG "
                    "commands", __func__);
                priv->get_cfg_unsafe = !0;
        }

        return 0;
} /* cypress_earthmate_startup */


static int cypress_hidcom_startup(struct usb_serial *serial)
{
        struct cypress_private *priv;

        dbg("%s", __func__);

        if (generic_startup(serial)) {
                dbg("%s - Failed setting up port %d", __func__,
                                serial->port[0]->number);
                return 1;
        }

        priv = usb_get_serial_port_data(serial->port[0]);
        priv->chiptype = CT_CYPHIDCOM;

        return 0;
} /* cypress_hidcom_startup */


static int cypress_ca42v2_startup(struct usb_serial *serial)
{
        struct cypress_private *priv;

        dbg("%s", __func__);

        if (generic_startup(serial)) {
                dbg("%s - Failed setting up port %d", __func__,
                                serial->port[0]->number);
                return 1;
        }

        priv = usb_get_serial_port_data(serial->port[0]);
        priv->chiptype = CT_CA42V2;

        return 0;
} /* cypress_ca42v2_startup */


static void cypress_release(struct usb_serial *serial)
{
        struct cypress_private *priv;

        dbg("%s - port %d", __func__, serial->port[0]->number);

        /* all open ports are closed at this point */

        priv = usb_get_serial_port_data(serial->port[0]);

        if (priv) {
                cypress_buf_free(priv->buf);
                kfree(priv);
        }
}


static int cypress_open(struct tty_struct *tty, struct usb_serial_port *port)
{
        struct cypress_private *priv = usb_get_serial_port_data(port);
        struct usb_serial *serial = port->serial;
        unsigned long flags;
        int result = 0;

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

        if (!priv->comm_is_ok)
                return -EIO;

        /* clear halts before open */
        usb_clear_halt(serial->dev, 0x81);
        usb_clear_halt(serial->dev, 0x02);

        spin_lock_irqsave(&priv->lock, flags);
        /* reset read/write statistics */
        priv->bytes_in = 0;
        priv->bytes_out = 0;
        priv->cmd_count = 0;
        priv->rx_flags = 0;
        spin_unlock_irqrestore(&priv->lock, flags);

        /* Set termios */
        cypress_send(port);

        if (tty)
                cypress_set_termios(tty, port, &priv->tmp_termios);

        /* setup the port and start reading from the device */
        if (!port->interrupt_in_urb) {
                dev_err(&port->dev, "%s - interrupt_in_urb is empty!\n",
                        __func__);
                return -1;
        }

        usb_fill_int_urb(port->interrupt_in_urb, serial->dev,
                usb_rcvintpipe(serial->dev, port->interrupt_in_endpointAddress),
                port->interrupt_in_urb->transfer_buffer,
                port->interrupt_in_urb->transfer_buffer_length,
                cypress_read_int_callback, port, priv->read_urb_interval);
        result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);

        if (result) {
                dev_err(&port->dev,
                        "%s - failed submitting read urb, error %d\n",
                                                        __func__, result);
                cypress_set_dead(port);
        }
        port->port.drain_delay = 256;
        return result;
} /* cypress_open */

static void cypress_dtr_rts(struct usb_serial_port *port, int on)
{
        struct cypress_private *priv = usb_get_serial_port_data(port);
        /* drop dtr and rts */
        priv = usb_get_serial_port_data(port);
        spin_lock_irq(&priv->lock);
        if (on == 0)
                priv->line_control = 0;
        else 
                priv->line_control = CONTROL_DTR | CONTROL_RTS;
        priv->cmd_ctrl = 1;
        spin_unlock_irq(&priv->lock);
        cypress_write(NULL, port, NULL, 0);
}

static void cypress_close(struct usb_serial_port *port)
{
        struct cypress_private *priv = usb_get_serial_port_data(port);

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

        /* writing is potentially harmful, lock must be taken */
        mutex_lock(&port->serial->disc_mutex);
        if (port->serial->disconnected) {
                mutex_unlock(&port->serial->disc_mutex);
                return;
        }
        cypress_buf_clear(priv->buf);
        dbg("%s - stopping urbs", __func__);
        usb_kill_urb(port->interrupt_in_urb);
        usb_kill_urb(port->interrupt_out_urb);


        if (stats)
                dev_info(&port->dev, "Statistics: %d Bytes In | %d Bytes Out | %d Commands Issued\n",
                        priv->bytes_in, priv->bytes_out, priv->cmd_count);
        mutex_unlock(&port->serial->disc_mutex);
} /* cypress_close */


static int cypress_write(struct tty_struct *tty, struct usb_serial_port *port,
                                        const unsigned char *buf, int count)
{
        struct cypress_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;

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

        /* line control commands, which need to be executed immediately,
           are not put into the buffer for obvious reasons.
         */
        if (priv->cmd_ctrl) {
                count = 0;
                goto finish;
        }

        if (!count)
                return count;

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

finish:
        cypress_send(port);

        return count;
} /* cypress_write */


static void cypress_send(struct usb_serial_port *port)
{
        int count = 0, result, offset, actual_size;
        struct cypress_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;

        if (!priv->comm_is_ok)
                return;

        dbg("%s - port %d", __func__, port->number);
        dbg("%s - interrupt out size is %d", __func__,
                                                port->interrupt_out_size);

        spin_lock_irqsave(&priv->lock, flags);
        if (priv->write_urb_in_use) {
                dbg("%s - can't write, urb in use", __func__);
                spin_unlock_irqrestore(&priv->lock, flags);
                return;
        }
        spin_unlock_irqrestore(&priv->lock, flags);

        /* clear buffer */
        memset(port->interrupt_out_urb->transfer_buffer, 0,
                                                port->interrupt_out_size);

        spin_lock_irqsave(&priv->lock, flags);
        switch (priv->pkt_fmt) {
        default:
        case packet_format_1:
                /* this is for the CY7C64013... */
                offset = 2;
                port->interrupt_out_buffer[0] = priv->line_control;
                break;
        case packet_format_2:
                /* this is for the CY7C63743... */
                offset = 1;
                port->interrupt_out_buffer[0] = priv->line_control;
                break;
        }

        if (priv->line_control & CONTROL_RESET)
                priv->line_control &= ~CONTROL_RESET;

        if (priv->cmd_ctrl) {
                priv->cmd_count++;
                dbg("%s - line control command being issued", __func__);
                spin_unlock_irqrestore(&priv->lock, flags);
                goto send;
        } else
                spin_unlock_irqrestore(&priv->lock, flags);

        count = cypress_buf_get(priv->buf, &port->interrupt_out_buffer[offset],
                                port->interrupt_out_size-offset);

        if (count == 0)
                return;

        switch (priv->pkt_fmt) {
        default:
        case packet_format_1:
                port->interrupt_out_buffer[1] = count;
                break;
        case packet_format_2:
                port->interrupt_out_buffer[0] |= count;
        }

        dbg("%s - count is %d", __func__, count);

send:
        spin_lock_irqsave(&priv->lock, flags);
        priv->write_urb_in_use = 1;
        spin_unlock_irqrestore(&priv->lock, flags);

        if (priv->cmd_ctrl)
                actual_size = 1;
        else
                actual_size = count +
                              (priv->pkt_fmt == packet_format_1 ? 2 : 1);

        usb_serial_debug_data(debug, &port->dev, __func__,
                port->interrupt_out_size,
                port->interrupt_out_urb->transfer_buffer);

        usb_fill_int_urb(port->interrupt_out_urb, port->serial->dev,
                usb_sndintpipe(port->serial->dev, port->interrupt_out_endpointAddress),
                port->interrupt_out_buffer, port->interrupt_out_size,
                cypress_write_int_callback, port, priv->write_urb_interval);
        result = usb_submit_urb(port->interrupt_out_urb, GFP_ATOMIC);
        if (result) {
                dev_err(&port->dev,
                                "%s - failed submitting write urb, error %d\n",
                                                        __func__, result);
                priv->write_urb_in_use = 0;
                cypress_set_dead(port);
        }

        spin_lock_irqsave(&priv->lock, flags);
        if (priv->cmd_ctrl)
                priv->cmd_ctrl = 0;

        /* do not count the line control and size bytes */
        priv->bytes_out += count;
        spin_unlock_irqrestore(&priv->lock, flags);

        usb_serial_port_softint(port);
} /* cypress_send */


/* returns how much space is available in the soft buffer */
static int cypress_write_room(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct cypress_private *priv = usb_get_serial_port_data(port);
        int room = 0;
        unsigned long flags;

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

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

        dbg("%s - returns %d", __func__, room);
        return room;
}


static int cypress_tiocmget(struct tty_struct *tty, struct file *file)
{
        struct usb_serial_port *port = tty->driver_data;
        struct cypress_private *priv = usb_get_serial_port_data(port);
        __u8 status, control;
        unsigned int result = 0;
        unsigned long flags;

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

        spin_lock_irqsave(&priv->lock, flags);
        control = priv->line_control;
        status = priv->current_status;
        spin_unlock_irqrestore(&priv->lock, flags);

        result = ((control & CONTROL_DTR)        ? TIOCM_DTR : 0)
                | ((control & CONTROL_RTS)       ? TIOCM_RTS : 0)
                | ((status & UART_CTS)        ? TIOCM_CTS : 0)
                | ((status & UART_DSR)        ? TIOCM_DSR : 0)
                | ((status & UART_RI)         ? TIOCM_RI  : 0)
                | ((status & UART_CD)         ? TIOCM_CD  : 0);

        dbg("%s - result = %x", __func__, result);

        return result;
}


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

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

        spin_lock_irqsave(&priv->lock, flags);
        if (set & TIOCM_RTS)
                priv->line_control |= CONTROL_RTS;
        if (set & TIOCM_DTR)
                priv->line_control |= CONTROL_DTR;
        if (clear & TIOCM_RTS)
                priv->line_control &= ~CONTROL_RTS;
        if (clear & TIOCM_DTR)
                priv->line_control &= ~CONTROL_DTR;
        priv->cmd_ctrl = 1;
        spin_unlock_irqrestore(&priv->lock, flags);

        return cypress_write(tty, port, NULL, 0);
}


static int cypress_ioctl(struct tty_struct *tty, struct file *file,
                                        unsigned int cmd, unsigned long arg)
{
        struct usb_serial_port *port = tty->driver_data;
        struct cypress_private *priv = usb_get_serial_port_data(port);

        dbg("%s - port %d, cmd 0x%.4x", __func__, port->number, cmd);

        switch (cmd) {
        /* This code comes from drivers/char/serial.c and ftdi_sio.c */
        case TIOCMIWAIT:
                while (priv != NULL) {
                        interruptible_sleep_on(&priv->delta_msr_wait);
                        /* see if a signal did it */
                        if (signal_pending(current))
                                return -ERESTARTSYS;
                        else {
                                char diff = priv->diff_status;
                                if (diff == 0)
                                        return -EIO; /* no change => error */

                                /* consume all events */
                                priv->diff_status = 0;

                                /* return 0 if caller wanted to know about
                                   these bits */
                                if (((arg & TIOCM_RNG) && (diff & UART_RI)) ||
                                    ((arg & TIOCM_DSR) && (diff & UART_DSR)) ||
                                    ((arg & TIOCM_CD) && (diff & UART_CD)) ||
                                    ((arg & TIOCM_CTS) && (diff & UART_CTS)))
                                        return 0;
                                /* otherwise caller can't care less about what
                                 * happened, and so we continue to wait for
                                 * more events.
                                 */
                        }
                }
                return 0;
        default:
                break;
        }
        dbg("%s - arg not supported - it was 0x%04x - check include/asm/ioctls.h", __func__, cmd);
        return -ENOIOCTLCMD;
} /* cypress_ioctl */


static void cypress_set_termios(struct tty_struct *tty,
        struct usb_serial_port *port, struct ktermios *old_termios)
{
        struct cypress_private *priv = usb_get_serial_port_data(port);
        int data_bits, stop_bits, parity_type, parity_enable;
        unsigned cflag, iflag;
        unsigned long flags;
        __u8 oldlines;
        int linechange = 0;

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

        spin_lock_irqsave(&priv->lock, flags);
        /* We can't clean this one up as we don't know the device type
           early enough */
        if (!priv->termios_initialized) {

                if (priv->chiptype == CT_EARTHMATE) {
                        *(tty->termios) = tty_std_termios;
                        tty->termios->c_cflag = B4800 | CS8 | CREAD | HUPCL |
                                CLOCAL;
                        tty->termios->c_ispeed = 4800;
                        tty->termios->c_ospeed = 4800;
                } else if (priv->chiptype == CT_CYPHIDCOM) {
                        *(tty->termios) = tty_std_termios;
                        tty->termios->c_cflag = B9600 | CS8 | CREAD | HUPCL |
                                CLOCAL;
                        tty->termios->c_ispeed = 9600;
                        tty->termios->c_ospeed = 9600;
                } else if (priv->chiptype == CT_CA42V2) {
                        *(tty->termios) = tty_std_termios;
                        tty->termios->c_cflag = B9600 | CS8 | CREAD | HUPCL |
                                CLOCAL;
                        tty->termios->c_ispeed = 9600;
                        tty->termios->c_ospeed = 9600;
                }
                priv->termios_initialized = 1;
        }
        spin_unlock_irqrestore(&priv->lock, flags);

        /* Unsupported features need clearing */
        tty->termios->c_cflag &= ~(CMSPAR|CRTSCTS);

        cflag = tty->termios->c_cflag;
        iflag = tty->termios->c_iflag;

        /* check if there are new settings */
        if (old_termios) {
                spin_lock_irqsave(&priv->lock, flags);
                priv->tmp_termios = *(tty->termios);
                spin_unlock_irqrestore(&priv->lock, flags);
        }

        /* set number of data bits, parity, stop bits */
        /* when parity is disabled the parity type bit is ignored */

        /* 1 means 2 stop bits, 0 means 1 stop bit */
        stop_bits = cflag & CSTOPB ? 1 : 0;

        if (cflag & PARENB) {
                parity_enable = 1;
                /* 1 means odd parity, 0 means even parity */
                parity_type = cflag & PARODD ? 1 : 0;
        } else
                parity_enable = parity_type = 0;

        switch (cflag & CSIZE) {
        case CS5:
                data_bits = 0;
                break;
        case CS6:
                data_bits = 1;
                break;
        case CS7:
                data_bits = 2;
                break;
        case CS8:
                data_bits = 3;
                break;
        default:
                dev_err(&port->dev, "%s - CSIZE was set, but not CS5-CS8\n",
                        __func__);
                data_bits = 3;
        }
        spin_lock_irqsave(&priv->lock, flags);
        oldlines = priv->line_control;
        if ((cflag & CBAUD) == B0) {
                /* drop dtr and rts */
                dbg("%s - dropping the lines, baud rate 0bps", __func__);
                priv->line_control &= ~(CONTROL_DTR | CONTROL_RTS);
        } else
                priv->line_control = (CONTROL_DTR | CONTROL_RTS);
        spin_unlock_irqrestore(&priv->lock, flags);

        dbg("%s - sending %d stop_bits, %d parity_enable, %d parity_type, "
                        "%d data_bits (+5)", __func__, stop_bits,
                        parity_enable, parity_type, data_bits);

        cypress_serial_control(tty, port, tty_get_baud_rate(tty),
                        data_bits, stop_bits,
                        parity_enable, parity_type,
                        0, CYPRESS_SET_CONFIG);

        /* we perform a CYPRESS_GET_CONFIG so that the current settings are
         * filled into the private structure this should confirm that all is
         * working if it returns what we just set */
        cypress_serial_control(tty, port, 0, 0, 0, 0, 0, 0, CYPRESS_GET_CONFIG);

        /* Here we can define custom tty settings for devices; the main tty
         * termios flag base comes from empeg.c */

        spin_lock_irqsave(&priv->lock, flags);
        if (priv->chiptype == CT_EARTHMATE && priv->baud_rate == 4800) {
                dbg("Using custom termios settings for a baud rate of "
                                "4800bps.");
                /* define custom termios settings for NMEA protocol */

                tty->termios->c_iflag /* input modes - */
                        &= ~(IGNBRK  /* disable ignore break */
                        | BRKINT     /* disable break causes interrupt */
                        | PARMRK     /* disable mark parity errors */
                        | ISTRIP     /* disable clear high bit of input char */
                        | INLCR      /* disable translate NL to CR */
                        | IGNCR      /* disable ignore CR */
                        | ICRNL      /* disable translate CR to NL */
                        | IXON);     /* disable enable XON/XOFF flow control */

                tty->termios->c_oflag /* output modes */
                        &= ~OPOST;    /* disable postprocess output char */

                tty->termios->c_lflag /* line discipline modes */
                        &= ~(ECHO     /* disable echo input characters */
                        | ECHONL      /* disable echo new line */
                        | ICANON      /* disable erase, kill, werase, and rprnt
                                         special characters */
                        | ISIG        /* disable interrupt, quit, and suspend
                                         special characters */
                        | IEXTEN);    /* disable non-POSIX special characters */
        } /* CT_CYPHIDCOM: Application should handle this for device */

        linechange = (priv->line_control != oldlines);
        spin_unlock_irqrestore(&priv->lock, flags);

        /* if necessary, set lines */
        if (linechange) {
                priv->cmd_ctrl = 1;
                cypress_write(tty, port, NULL, 0);
        }
} /* cypress_set_termios */


/* returns amount of data still left in soft buffer */
static int cypress_chars_in_buffer(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct cypress_private *priv = usb_get_serial_port_data(port);
        int chars = 0;
        unsigned long flags;

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

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

        dbg("%s - returns %d", __func__, chars);
        return chars;
}


static void cypress_throttle(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct cypress_private *priv = usb_get_serial_port_data(port);

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

        spin_lock_irq(&priv->lock);
        priv->rx_flags = THROTTLED;
        spin_unlock_irq(&priv->lock);
}


static void cypress_unthrottle(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct cypress_private *priv = usb_get_serial_port_data(port);
        int actually_throttled, result;

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

        spin_lock_irq(&priv->lock);
        actually_throttled = priv->rx_flags & ACTUALLY_THROTTLED;
        priv->rx_flags = 0;
        spin_unlock_irq(&priv->lock);

        if (!priv->comm_is_ok)
                return;

        if (actually_throttled) {
                port->interrupt_in_urb->dev = port->serial->dev;

                result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
                if (result) {
                        dev_err(&port->dev, "%s - failed submitting read urb, "
                                        "error %d\n", __func__, result);
                        cypress_set_dead(port);
                }
        }
}


static void cypress_read_int_callback(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct cypress_private *priv = usb_get_serial_port_data(port);
        struct tty_struct *tty;
        unsigned char *data = urb->transfer_buffer;
        unsigned long flags;
        char tty_flag = TTY_NORMAL;
        int havedata = 0;
        int bytes = 0;
        int result;
        int i = 0;
        int status = urb->status;

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

        switch (status) {
        case 0: /* success */
                break;
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
                /* precursor to disconnect so just go away */
                return;
        case -EPIPE:
                /* Can't call usb_clear_halt while in_interrupt */
                /* FALLS THROUGH */
        default:
                /* something ugly is going on... */
                dev_err(&urb->dev->dev,
                        "%s - unexpected nonzero read status received: %d\n",
                                                        __func__, status);
                cypress_set_dead(port);
                return;
        }

        spin_lock_irqsave(&priv->lock, flags);
        if (priv->rx_flags & THROTTLED) {
                dbg("%s - now throttling", __func__);
                priv->rx_flags |= ACTUALLY_THROTTLED;
                spin_unlock_irqrestore(&priv->lock, flags);
                return;
        }
        spin_unlock_irqrestore(&priv->lock, flags);

        tty = tty_port_tty_get(&port->port);
        if (!tty) {
                dbg("%s - bad tty pointer - exiting", __func__);
                return;
        }

        spin_lock_irqsave(&priv->lock, flags);
        result = urb->actual_length;
        switch (priv->pkt_fmt) {
        default:
        case packet_format_1:
                /* This is for the CY7C64013... */
                priv->current_status = data[0] & 0xF8;
                bytes = data[1] + 2;
                i = 2;
                if (bytes > 2)
                        havedata = 1;
                break;
        case packet_format_2:
                /* This is for the CY7C63743... */
                priv->current_status = data[0] & 0xF8;
                bytes = (data[0] & 0x07) + 1;
                i = 1;
                if (bytes > 1)
                        havedata = 1;
                break;
        }
        spin_unlock_irqrestore(&priv->lock, flags);
        if (result < bytes) {
                dbg("%s - wrong packet size - received %d bytes but packet "
                    "said %d bytes", __func__, result, bytes);
                goto continue_read;
        }

        usb_serial_debug_data(debug, &port->dev, __func__,
                                                urb->actual_length, data);

        spin_lock_irqsave(&priv->lock, flags);
        /* check to see if status has changed */
        if (priv->current_status != priv->prev_status) {
                priv->diff_status |= priv->current_status ^
                        priv->prev_status;
                wake_up_interruptible(&priv->delta_msr_wait);
                priv->prev_status = priv->current_status;
        }
        spin_unlock_irqrestore(&priv->lock, flags);

        /* hangup, as defined in acm.c... this might be a bad place for it
         * though */
        if (tty && !(tty->termios->c_cflag & CLOCAL) &&
                        !(priv->current_status & UART_CD)) {
                dbg("%s - calling hangup", __func__);
                tty_hangup(tty);
                goto continue_read;
        }

        /* There is one error bit... I'm assuming it is a parity error
         * indicator as the generic firmware will set this bit to 1 if a
         * parity error occurs.
         * I can not find reference to any other error events. */
        spin_lock_irqsave(&priv->lock, flags);
        if (priv->current_status & CYP_ERROR) {
                spin_unlock_irqrestore(&priv->lock, flags);
                tty_flag = TTY_PARITY;
                dbg("%s - Parity Error detected", __func__);
        } else
                spin_unlock_irqrestore(&priv->lock, flags);

        /* process read if there is data other than line status */
        if (tty && (bytes > i)) {
                bytes = tty_buffer_request_room(tty, bytes);
                for (; i < bytes ; ++i) {
                        dbg("pushing byte number %d - %d - %c", i, data[i],
                                        data[i]);
                        tty_insert_flip_char(tty, data[i], tty_flag);
                }
                tty_flip_buffer_push(tty);
        }

        spin_lock_irqsave(&priv->lock, flags);
        /* control and status byte(s) are also counted */
        priv->bytes_in += bytes;
        spin_unlock_irqrestore(&priv->lock, flags);

continue_read:
        tty_kref_put(tty);

        /* Continue trying to always read... unless the port has closed. */

        if (port->port.count > 0 && priv->comm_is_ok) {
                usb_fill_int_urb(port->interrupt_in_urb, port->serial->dev,
                                usb_rcvintpipe(port->serial->dev,
                                        port->interrupt_in_endpointAddress),
                                port->interrupt_in_urb->transfer_buffer,
                                port->interrupt_in_urb->transfer_buffer_length,
                                cypress_read_int_callback, port,
                                priv->read_urb_interval);
                result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
                if (result) {
                        dev_err(&urb->dev->dev, "%s - failed resubmitting "
                                        "read urb, error %d\n", __func__,
                                        result);
                        cypress_set_dead(port);
                }
        }

        return;
} /* cypress_read_int_callback */


static void cypress_write_int_callback(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct cypress_private *priv = usb_get_serial_port_data(port);
        int result;
        int status = urb->status;

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

        switch (status) {
        case 0:
                /* success */
                break;
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
                /* this urb is terminated, clean up */
                dbg("%s - urb shutting down with status: %d",
                                                __func__, status);
                priv->write_urb_in_use = 0;
                return;
        case -EPIPE: /* no break needed; clear halt and resubmit */
                if (!priv->comm_is_ok)
                        break;
                usb_clear_halt(port->serial->dev, 0x02);
                /* error in the urb, so we have to resubmit it */
                dbg("%s - nonzero write bulk status received: %d",
                        __func__, status);
                port->interrupt_out_urb->transfer_buffer_length = 1;
                port->interrupt_out_urb->dev = port->serial->dev;
                result = usb_submit_urb(port->interrupt_out_urb, GFP_ATOMIC);
                if (!result)
                        return;
                dev_err(&urb->dev->dev,
                        "%s - failed resubmitting write urb, error %d\n",
                                                        __func__, result);
                cypress_set_dead(port);
                break;
        default:
                dev_err(&urb->dev->dev,
                         "%s - unexpected nonzero write status received: %d\n",
                                                        __func__, status);
                cypress_set_dead(port);
                break;
        }
        priv->write_urb_in_use = 0;

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


/*****************************************************************************
 * Write buffer functions - buffering code from pl2303 used
 *****************************************************************************/

/*
 * cypress_buf_alloc
 *
 * Allocate a circular buffer and all associated memory.
 */

static struct cypress_buf *cypress_buf_alloc(unsigned int size)
{

        struct cypress_buf *cb;


        if (size == 0)
                return NULL;

        cb = kmalloc(sizeof(struct cypress_buf), GFP_KERNEL);
        if (cb == NULL)
                return NULL;

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

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

        return cb;

}


/*
 * cypress_buf_free
 *
 * Free the buffer and all associated memory.
 */

static void cypress_buf_free(struct cypress_buf *cb)
{
        if (cb) {
                kfree(cb->buf_buf);
                kfree(cb);
        }
}


/*
 * cypress_buf_clear
 *
 * Clear out all data in the circular buffer.
 */

static void cypress_buf_clear(struct cypress_buf *cb)
{
        if (cb != NULL)
                cb->buf_get = cb->buf_put;
                /* equivalent to a get of all data available */
}


/*
 * cypress_buf_data_avail
 *
 * Return the number of bytes of data available in the circular
 * buffer.
 */

static unsigned int cypress_buf_data_avail(struct cypress_buf *cb)
{
        if (cb != NULL)
                return (cb->buf_size + cb->buf_put - cb->buf_get)
                                                        % cb->buf_size;
        else
                return 0;
}


/*
 * cypress_buf_space_avail
 *
 * Return the number of bytes of space available in the circular
 * buffer.
 */

static unsigned int cypress_buf_space_avail(struct cypress_buf *cb)
{
        if (cb != NULL)
                return (cb->buf_size + cb->buf_get - cb->buf_put - 1)
                                                        % cb->buf_size;
        else
                return 0;
}


/*
 * cypress_buf_put
 *
 * Copy data data from a user buffer and put it into the circular buffer.
 * Restrict to the amount of space available.
 *
 * Return the number of bytes copied.
 */

static unsigned int cypress_buf_put(struct cypress_buf *cb, const char *buf,
        unsigned int count)
{

        unsigned int len;


        if (cb == NULL)
                return 0;

        len  = cypress_buf_space_avail(cb);
        if (count > len)
                count = len;

        if (count == 0)
                return 0;

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

        return count;

}


/*
 * cypress_buf_get
 *
 * Get data from the circular buffer and copy to the given buffer.
 * Restrict to the amount of data available.
 *
 * Return the number of bytes copied.
 */

static unsigned int cypress_buf_get(struct cypress_buf *cb, char *buf,
        unsigned int count)
{

        unsigned int len;


        if (cb == NULL)
                return 0;

        len = cypress_buf_data_avail(cb);
        if (count > len)
                count = len;

        if (count == 0)
                return 0;

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

        return count;

}

/*****************************************************************************
 * Module functions
 *****************************************************************************/

static int __init cypress_init(void)
{
        int retval;

        dbg("%s", __func__);

        retval = usb_serial_register(&cypress_earthmate_device);
        if (retval)
                goto failed_em_register;
        retval = usb_serial_register(&cypress_hidcom_device);
        if (retval)
                goto failed_hidcom_register;
        retval = usb_serial_register(&cypress_ca42v2_device);
        if (retval)
                goto failed_ca42v2_register;
        retval = usb_register(&cypress_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(&cypress_ca42v2_device);
failed_ca42v2_register:
        usb_serial_deregister(&cypress_hidcom_device);
failed_hidcom_register:
        usb_serial_deregister(&cypress_earthmate_device);
failed_em_register:
        return retval;
}


static void __exit cypress_exit(void)
{
        dbg("%s", __func__);

        usb_deregister(&cypress_driver);
        usb_serial_deregister(&cypress_earthmate_device);
        usb_serial_deregister(&cypress_hidcom_device);
        usb_serial_deregister(&cypress_ca42v2_device);
}


module_init(cypress_init);
module_exit(cypress_exit);

MODULE_AUTHOR(DRIVER_AUTHOR);
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");
module_param(stats, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(stats, "Enable statistics or not");
module_param(interval, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(interval, "Overrides interrupt interval");