mos7720.c

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/*
 * mos7720.c
 *   Controls the Moschip 7720 usb to dual port serial convertor
 *
 * Copyright 2006 Moschip Semiconductor Tech. Ltd.
 *
 * 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, version 2 of the License.
 *
 * Developed by:
 *  Vijaya Kumar <[email protected]>
 *  Ajay Kumar <[email protected]>
 *  Gurudeva <[email protected]>
 *
 * Cleaned up from the original by:
 *  Greg Kroah-Hartman <[email protected]>
 *
 * Originally based on drivers/usb/serial/io_edgeport.c which is:
 *  Copyright (C) 2000 Inside Out Networks, All rights reserved.
 *  Copyright (C) 2001-2002 Greg Kroah-Hartman <[email protected]>
 */
#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/serial.h>
#include <linux/serial_reg.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/uaccess.h>
#include <linux/parport.h>

/*
 * Version Information
 */
#define DRIVER_VERSION "2.1"
#define DRIVER_AUTHOR "Aspire Communications pvt Ltd."
#define DRIVER_DESC "Moschip USB Serial Driver"

/* default urb timeout */
#define MOS_WDR_TIMEOUT (HZ * 5)

#define MOS_MAX_PORT    0x02
#define MOS_WRITE   0x0E
#define MOS_READ    0x0D

/* Interrupt Rotinue Defines    */
#define SERIAL_IIR_RLS  0x06
#define SERIAL_IIR_RDA  0x04
#define SERIAL_IIR_CTI  0x0c
#define SERIAL_IIR_THR  0x02
#define SERIAL_IIR_MS   0x00

#define NUM_URBS            16  /* URB Count */
#define URB_TRANSFER_BUFFER_SIZE    32  /* URB Size */

/* This structure holds all of the local serial port information */
struct moschip_port {
    __u8    shadowLCR;      /* last LCR value received */
    __u8    shadowMCR;      /* last MCR value received */
    __u8    shadowMSR;      /* last MSR value received */
    char            open;
    struct async_icount icount;
    struct usb_serial_port  *port;  /* loop back to the owner */
    struct urb      *write_urb_pool[NUM_URBS];
};

static struct usb_serial_driver moschip7720_2port_driver;

#define USB_VENDOR_ID_MOSCHIP       0x9710
#define MOSCHIP_DEVICE_ID_7720      0x7720
#define MOSCHIP_DEVICE_ID_7715      0x7715

static const struct usb_device_id id_table[] = {
    { USB_DEVICE(USB_VENDOR_ID_MOSCHIP, MOSCHIP_DEVICE_ID_7720) },
    { USB_DEVICE(USB_VENDOR_ID_MOSCHIP, MOSCHIP_DEVICE_ID_7715) },
    { } /* terminating entry */
};
MODULE_DEVICE_TABLE(usb, id_table);

#ifdef CONFIG_USB_SERIAL_MOS7715_PARPORT

/* initial values for parport regs */
#define DCR_INIT_VAL       0x0c /* SLCTIN, nINIT */
#define ECR_INIT_VAL       0x00 /* SPP mode */

struct urbtracker {
    struct mos7715_parport  *mos_parport;
    struct list_head        urblist_entry;
    struct kref             ref_count;
    struct urb              *urb;
};

enum mos7715_pp_modes {
    SPP = 0<<5,
    PS2 = 1<<5,      /* moschip calls this 'NIBBLE' mode */
    PPF = 2<<5,  /* moschip calls this 'CB-FIFO mode */
};

struct mos7715_parport {
    struct parport          *pp;           /* back to containing struct */
    struct kref             ref_count;     /* to instance of this struct */
    struct list_head        deferred_urbs; /* list deferred async urbs */
    struct list_head        active_urbs;   /* list async urbs in flight */
    spinlock_t              listlock;      /* protects list access */
    bool                    msg_pending;   /* usb sync call pending */
    struct completion       syncmsg_compl; /* usb sync call completed */
    struct tasklet_struct   urb_tasklet;   /* for sending deferred urbs */
    struct usb_serial       *serial;       /* back to containing struct */
    __u8                    shadowECR;     /* parallel port regs... */
    __u8                    shadowDCR;
    atomic_t                shadowDSR;     /* updated in int-in callback */
};

/* lock guards against dereferencing NULL ptr in parport ops callbacks */
static DEFINE_SPINLOCK(release_lock);

#endif  /* CONFIG_USB_SERIAL_MOS7715_PARPORT */

static const unsigned int dummy; /* for clarity in register access fns */

enum mos_regs {
    THR,              /* serial port regs */
    RHR,
    IER,
    FCR,
    ISR,
    LCR,
    MCR,
    LSR,
    MSR,
    SPR,
    DLL,
    DLM,
    DPR,              /* parallel port regs */
    DSR,
    DCR,
    ECR,
    SP1_REG,          /* device control regs */
    SP2_REG,          /* serial port 2 (7720 only) */
    PP_REG,
    SP_CONTROL_REG,
};

/*
 * Return the correct value for the Windex field of the setup packet
 * for a control endpoint message.  See the 7715 datasheet.
 */
static inline __u16 get_reg_index(enum mos_regs reg)
{
    static const __u16 mos7715_index_lookup_table[] = {
        0x00,       /* THR */
        0x00,       /* RHR */
        0x01,       /* IER */
        0x02,       /* FCR */
        0x02,       /* ISR */
        0x03,       /* LCR */
        0x04,       /* MCR */
        0x05,       /* LSR */
        0x06,       /* MSR */
        0x07,       /* SPR */
        0x00,       /* DLL */
        0x01,       /* DLM */
        0x00,       /* DPR */
        0x01,       /* DSR */
        0x02,       /* DCR */
        0x0a,       /* ECR */
        0x01,       /* SP1_REG */
        0x02,       /* SP2_REG (7720 only) */
        0x04,       /* PP_REG (7715 only) */
        0x08,       /* SP_CONTROL_REG */
    };
    return mos7715_index_lookup_table[reg];
}

/*
 * Return the correct value for the upper byte of the Wvalue field of
 * the setup packet for a control endpoint message.
 */
static inline __u16 get_reg_value(enum mos_regs reg,
                  unsigned int serial_portnum)
{
    if (reg >= SP1_REG)       /* control reg */
        return 0x0000;

    else if (reg >= DPR)          /* parallel port reg (7715 only) */
        return 0x0100;

    else                  /* serial port reg */
        return (serial_portnum + 2) << 8;
}

/*
 * Write data byte to the specified device register.  The data is embedded in
 * the value field of the setup packet. serial_portnum is ignored for registers
 * not specific to a particular serial port.
 */
static int write_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
             enum mos_regs reg, __u8 data)
{
    struct usb_device *usbdev = serial->dev;
    unsigned int pipe = usb_sndctrlpipe(usbdev, 0);
    __u8 request = (__u8)0x0e;
    __u8 requesttype = (__u8)0x40;
    __u16 index = get_reg_index(reg);
    __u16 value = get_reg_value(reg, serial_portnum) + data;
    int status = usb_control_msg(usbdev, pipe, request, requesttype, value,
                     index, NULL, 0, MOS_WDR_TIMEOUT);
    if (status < 0)
        dev_err(&usbdev->dev,
            "mos7720: usb_control_msg() failed: %d", status);
    return status;
}

/*
 * Read data byte from the specified device register.  The data returned by the
 * device is embedded in the value field of the setup packet.  serial_portnum is
 * ignored for registers that are not specific to a particular serial port.
 */
static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
            enum mos_regs reg, __u8 *data)
{
    struct usb_device *usbdev = serial->dev;
    unsigned int pipe = usb_rcvctrlpipe(usbdev, 0);
    __u8 request = (__u8)0x0d;
    __u8 requesttype = (__u8)0xc0;
    __u16 index = get_reg_index(reg);
    __u16 value = get_reg_value(reg, serial_portnum);
    int status = usb_control_msg(usbdev, pipe, request, requesttype, value,
                     index, data, 1, MOS_WDR_TIMEOUT);
    if (status < 0)
        dev_err(&usbdev->dev,
            "mos7720: usb_control_msg() failed: %d", status);
    return status;
}

#ifdef CONFIG_USB_SERIAL_MOS7715_PARPORT

static inline int mos7715_change_mode(struct mos7715_parport *mos_parport,
                      enum mos7715_pp_modes mode)
{
    mos_parport->shadowECR = mode;
    write_mos_reg(mos_parport->serial, dummy, ECR, mos_parport->shadowECR);
    return 0;
}

static void destroy_mos_parport(struct kref *kref)
{
    struct mos7715_parport *mos_parport =
        container_of(kref, struct mos7715_parport, ref_count);

    kfree(mos_parport);
}

static void destroy_urbtracker(struct kref *kref)
{
    struct urbtracker *urbtrack =
        container_of(kref, struct urbtracker, ref_count);
    struct mos7715_parport *mos_parport = urbtrack->mos_parport;

    usb_free_urb(urbtrack->urb);
    kfree(urbtrack);
    kref_put(&mos_parport->ref_count, destroy_mos_parport);
}

/*
 * This runs as a tasklet when sending an urb in a non-blocking parallel
 * port callback had to be deferred because the disconnect mutex could not be
 * obtained at the time.
 */
static void send_deferred_urbs(unsigned long _mos_parport)
{
    int ret_val;
    unsigned long flags;
    struct mos7715_parport *mos_parport = (void *)_mos_parport;
    struct urbtracker *urbtrack, *tmp;
    struct list_head *cursor, *next;
    struct device *dev;

    /* if release function ran, game over */
    if (unlikely(mos_parport->serial == NULL))
        return;

    dev = &mos_parport->serial->dev->dev;

    /* try again to get the mutex */
    if (!mutex_trylock(&mos_parport->serial->disc_mutex)) {
        dev_dbg(dev, "%s: rescheduling tasklet\n", __func__);
        tasklet_schedule(&mos_parport->urb_tasklet);
        return;
    }

    /* if device disconnected, game over */
    if (unlikely(mos_parport->serial->disconnected)) {
        mutex_unlock(&mos_parport->serial->disc_mutex);
        return;
    }

    spin_lock_irqsave(&mos_parport->listlock, flags);
    if (list_empty(&mos_parport->deferred_urbs)) {
        spin_unlock_irqrestore(&mos_parport->listlock, flags);
        mutex_unlock(&mos_parport->serial->disc_mutex);
        dev_dbg(dev, "%s: deferred_urbs list empty\n", __func__);
        return;
    }

    /* move contents of deferred_urbs list to active_urbs list and submit */
    list_for_each_safe(cursor, next, &mos_parport->deferred_urbs)
        list_move_tail(cursor, &mos_parport->active_urbs);
    list_for_each_entry_safe(urbtrack, tmp, &mos_parport->active_urbs,
                urblist_entry) {
        ret_val = usb_submit_urb(urbtrack->urb, GFP_ATOMIC);
        dev_dbg(dev, "%s: urb submitted\n", __func__);
        if (ret_val) {
            dev_err(dev, "usb_submit_urb() failed: %d\n", ret_val);
            list_del(&urbtrack->urblist_entry);
            kref_put(&urbtrack->ref_count, destroy_urbtracker);
        }
    }
    spin_unlock_irqrestore(&mos_parport->listlock, flags);
    mutex_unlock(&mos_parport->serial->disc_mutex);
}

/* callback for parallel port control urbs submitted asynchronously */
static void async_complete(struct urb *urb)
{
    struct urbtracker *urbtrack = urb->context;
    int status = urb->status;

    if (unlikely(status))
        dev_dbg(&urb->dev->dev, "%s - nonzero urb status received: %d\n", __func__, status);

    /* remove the urbtracker from the active_urbs list */
    spin_lock(&urbtrack->mos_parport->listlock);
    list_del(&urbtrack->urblist_entry);
    spin_unlock(&urbtrack->mos_parport->listlock);
    kref_put(&urbtrack->ref_count, destroy_urbtracker);
}

static int write_parport_reg_nonblock(struct mos7715_parport *mos_parport,
                      enum mos_regs reg, __u8 data)
{
    struct urbtracker *urbtrack;
    int ret_val;
    unsigned long flags;
    struct usb_ctrlrequest setup;
    struct usb_serial *serial = mos_parport->serial;
    struct usb_device *usbdev = serial->dev;

    /* create and initialize the control urb and containing urbtracker */
    urbtrack = kmalloc(sizeof(struct urbtracker), GFP_ATOMIC);
    if (urbtrack == NULL) {
        dev_err(&usbdev->dev, "out of memory");
        return -ENOMEM;
    }
    kref_get(&mos_parport->ref_count);
    urbtrack->mos_parport = mos_parport;
    urbtrack->urb = usb_alloc_urb(0, GFP_ATOMIC);
    if (urbtrack->urb == NULL) {
        dev_err(&usbdev->dev, "out of urbs");
        kfree(urbtrack);
        return -ENOMEM;
    }
    setup.bRequestType = (__u8)0x40;
    setup.bRequest = (__u8)0x0e;
    setup.wValue = get_reg_value(reg, dummy);
    setup.wIndex = get_reg_index(reg);
    setup.wLength = 0;
    usb_fill_control_urb(urbtrack->urb, usbdev,
                 usb_sndctrlpipe(usbdev, 0),
                 (unsigned char *)&setup,
                 NULL, 0, async_complete, urbtrack);
    kref_init(&urbtrack->ref_count);
    INIT_LIST_HEAD(&urbtrack->urblist_entry);

    /*
     * get the disconnect mutex, or add tracker to the deferred_urbs list
     * and schedule a tasklet to try again later
     */
    if (!mutex_trylock(&serial->disc_mutex)) {
        spin_lock_irqsave(&mos_parport->listlock, flags);
        list_add_tail(&urbtrack->urblist_entry,
                  &mos_parport->deferred_urbs);
        spin_unlock_irqrestore(&mos_parport->listlock, flags);
        tasklet_schedule(&mos_parport->urb_tasklet);
        dev_dbg(&usbdev->dev, "tasklet scheduled");
        return 0;
    }

    /* bail if device disconnected */
    if (serial->disconnected) {
        kref_put(&urbtrack->ref_count, destroy_urbtracker);
        mutex_unlock(&serial->disc_mutex);
        return -ENODEV;
    }

    /* add the tracker to the active_urbs list and submit */
    spin_lock_irqsave(&mos_parport->listlock, flags);
    list_add_tail(&urbtrack->urblist_entry, &mos_parport->active_urbs);
    spin_unlock_irqrestore(&mos_parport->listlock, flags);
    ret_val = usb_submit_urb(urbtrack->urb, GFP_ATOMIC);
    mutex_unlock(&serial->disc_mutex);
    if (ret_val) {
        dev_err(&usbdev->dev,
            "%s: submit_urb() failed: %d", __func__, ret_val);
        spin_lock_irqsave(&mos_parport->listlock, flags);
        list_del(&urbtrack->urblist_entry);
        spin_unlock_irqrestore(&mos_parport->listlock, flags);
        kref_put(&urbtrack->ref_count, destroy_urbtracker);
        return ret_val;
    }
    return 0;
}

/*
 * This is the the common top part of all parallel port callback operations that
 * send synchronous messages to the device.  This implements convoluted locking
 * that avoids two scenarios: (1) a port operation is called after usbserial
 * has called our release function, at which point struct mos7715_parport has
 * been destroyed, and (2) the device has been disconnected, but usbserial has
 * not called the release function yet because someone has a serial port open.
 * The shared release_lock prevents the first, and the mutex and disconnected
 * flag maintained by usbserial covers the second.  We also use the msg_pending
 * flag to ensure that all synchronous usb messgage calls have completed before
 * our release function can return.
 */
static int parport_prologue(struct parport *pp)
{
    struct mos7715_parport *mos_parport;

    spin_lock(&release_lock);
    mos_parport = pp->private_data;
    if (unlikely(mos_parport == NULL)) {
        /* release fn called, port struct destroyed */
        spin_unlock(&release_lock);
        return -1;
    }
    mos_parport->msg_pending = true;   /* synch usb call pending */
    INIT_COMPLETION(mos_parport->syncmsg_compl);
    spin_unlock(&release_lock);

    mutex_lock(&mos_parport->serial->disc_mutex);
    if (mos_parport->serial->disconnected) {
        /* device disconnected */
        mutex_unlock(&mos_parport->serial->disc_mutex);
        mos_parport->msg_pending = false;
        complete(&mos_parport->syncmsg_compl);
        return -1;
    }

    return 0;
}

/*
 * This is the the common bottom part of all parallel port functions that send
 * synchronous messages to the device.
 */
static inline void parport_epilogue(struct parport *pp)
{
    struct mos7715_parport *mos_parport = pp->private_data;
    mutex_unlock(&mos_parport->serial->disc_mutex);
    mos_parport->msg_pending = false;
    complete(&mos_parport->syncmsg_compl);
}

static void parport_mos7715_write_data(struct parport *pp, unsigned char d)
{
    struct mos7715_parport *mos_parport = pp->private_data;

    if (parport_prologue(pp) < 0)
        return;
    mos7715_change_mode(mos_parport, SPP);
    write_mos_reg(mos_parport->serial, dummy, DPR, (__u8)d);
    parport_epilogue(pp);
}

static unsigned char parport_mos7715_read_data(struct parport *pp)
{
    struct mos7715_parport *mos_parport = pp->private_data;
    unsigned char d;

    if (parport_prologue(pp) < 0)
        return 0;
    read_mos_reg(mos_parport->serial, dummy, DPR, &d);
    parport_epilogue(pp);
    return d;
}

static void parport_mos7715_write_control(struct parport *pp, unsigned char d)
{
    struct mos7715_parport *mos_parport = pp->private_data;
    __u8 data;

    if (parport_prologue(pp) < 0)
        return;
    data = ((__u8)d & 0x0f) | (mos_parport->shadowDCR & 0xf0);
    write_mos_reg(mos_parport->serial, dummy, DCR, data);
    mos_parport->shadowDCR = data;
    parport_epilogue(pp);
}

static unsigned char parport_mos7715_read_control(struct parport *pp)
{
    struct mos7715_parport *mos_parport = pp->private_data;
    __u8 dcr;

    spin_lock(&release_lock);
    mos_parport = pp->private_data;
    if (unlikely(mos_parport == NULL)) {
        spin_unlock(&release_lock);
        return 0;
    }
    dcr = mos_parport->shadowDCR & 0x0f;
    spin_unlock(&release_lock);
    return dcr;
}

static unsigned char parport_mos7715_frob_control(struct parport *pp,
                          unsigned char mask,
                          unsigned char val)
{
    struct mos7715_parport *mos_parport = pp->private_data;
    __u8 dcr;

    mask &= 0x0f;
    val &= 0x0f;
    if (parport_prologue(pp) < 0)
        return 0;
    mos_parport->shadowDCR = (mos_parport->shadowDCR & (~mask)) ^ val;
    write_mos_reg(mos_parport->serial, dummy, DCR, mos_parport->shadowDCR);
    dcr = mos_parport->shadowDCR & 0x0f;
    parport_epilogue(pp);
    return dcr;
}

static unsigned char parport_mos7715_read_status(struct parport *pp)
{
    unsigned char status;
    struct mos7715_parport *mos_parport = pp->private_data;

    spin_lock(&release_lock);
    mos_parport = pp->private_data;
    if (unlikely(mos_parport == NULL)) {    /* release called */
        spin_unlock(&release_lock);
        return 0;
    }
    status = atomic_read(&mos_parport->shadowDSR) & 0xf8;
    spin_unlock(&release_lock);
    return status;
}

static void parport_mos7715_enable_irq(struct parport *pp)
{
}

static void parport_mos7715_disable_irq(struct parport *pp)
{
}

static void parport_mos7715_data_forward(struct parport *pp)
{
    struct mos7715_parport *mos_parport = pp->private_data;

    if (parport_prologue(pp) < 0)
        return;
    mos7715_change_mode(mos_parport, PS2);
    mos_parport->shadowDCR &=  ~0x20;
    write_mos_reg(mos_parport->serial, dummy, DCR, mos_parport->shadowDCR);
    parport_epilogue(pp);
}

static void parport_mos7715_data_reverse(struct parport *pp)
{
    struct mos7715_parport *mos_parport = pp->private_data;

    if (parport_prologue(pp) < 0)
        return;
    mos7715_change_mode(mos_parport, PS2);
    mos_parport->shadowDCR |= 0x20;
    write_mos_reg(mos_parport->serial, dummy, DCR, mos_parport->shadowDCR);
    parport_epilogue(pp);
}

static void parport_mos7715_init_state(struct pardevice *dev,
                       struct parport_state *s)
{
    s->u.pc.ctr = DCR_INIT_VAL;
    s->u.pc.ecr = ECR_INIT_VAL;
}

/* N.B. Parport core code requires that this function not block */
static void parport_mos7715_save_state(struct parport *pp,
                       struct parport_state *s)
{
    struct mos7715_parport *mos_parport;

    spin_lock(&release_lock);
    mos_parport = pp->private_data;
    if (unlikely(mos_parport == NULL)) {    /* release called */
        spin_unlock(&release_lock);
        return;
    }
    s->u.pc.ctr = mos_parport->shadowDCR;
    s->u.pc.ecr = mos_parport->shadowECR;
    spin_unlock(&release_lock);
}

/* N.B. Parport core code requires that this function not block */
static void parport_mos7715_restore_state(struct parport *pp,
                      struct parport_state *s)
{
    struct mos7715_parport *mos_parport;

    spin_lock(&release_lock);
    mos_parport = pp->private_data;
    if (unlikely(mos_parport == NULL)) {    /* release called */
        spin_unlock(&release_lock);
        return;
    }
    write_parport_reg_nonblock(mos_parport, DCR, mos_parport->shadowDCR);
    write_parport_reg_nonblock(mos_parport, ECR, mos_parport->shadowECR);
    spin_unlock(&release_lock);
}

static size_t parport_mos7715_write_compat(struct parport *pp,
                       const void *buffer,
                       size_t len, int flags)
{
    int retval;
    struct mos7715_parport *mos_parport = pp->private_data;
    int actual_len;

    if (parport_prologue(pp) < 0)
        return 0;
    mos7715_change_mode(mos_parport, PPF);
    retval = usb_bulk_msg(mos_parport->serial->dev,
                  usb_sndbulkpipe(mos_parport->serial->dev, 2),
                  (void *)buffer, len, &actual_len,
                  MOS_WDR_TIMEOUT);
    parport_epilogue(pp);
    if (retval) {
        dev_err(&mos_parport->serial->dev->dev,
            "mos7720: usb_bulk_msg() failed: %d", retval);
        return 0;
    }
    return actual_len;
}

static struct parport_operations parport_mos7715_ops = {
    .owner =        THIS_MODULE,
    .write_data =       parport_mos7715_write_data,
    .read_data =        parport_mos7715_read_data,

    .write_control =    parport_mos7715_write_control,
    .read_control =     parport_mos7715_read_control,
    .frob_control =     parport_mos7715_frob_control,

    .read_status =      parport_mos7715_read_status,

    .enable_irq =       parport_mos7715_enable_irq,
    .disable_irq =      parport_mos7715_disable_irq,

    .data_forward =     parport_mos7715_data_forward,
    .data_reverse =     parport_mos7715_data_reverse,

    .init_state =       parport_mos7715_init_state,
    .save_state =       parport_mos7715_save_state,
    .restore_state =    parport_mos7715_restore_state,

    .compat_write_data =    parport_mos7715_write_compat,

    .nibble_read_data = parport_ieee1284_read_nibble,
    .byte_read_data =   parport_ieee1284_read_byte,
};

/*
 * Allocate and initialize parallel port control struct, initialize
 * the parallel port hardware device, and register with the parport subsystem.
 */
static int mos7715_parport_init(struct usb_serial *serial)
{
    struct mos7715_parport *mos_parport;

    /* allocate and initialize parallel port control struct */
    mos_parport = kzalloc(sizeof(struct mos7715_parport), GFP_KERNEL);
    if (mos_parport == NULL) {
        dev_dbg(&serial->dev->dev, "%s: kzalloc failed\n", __func__);
        return -ENOMEM;
    }
    mos_parport->msg_pending = false;
    kref_init(&mos_parport->ref_count);
    spin_lock_init(&mos_parport->listlock);
    INIT_LIST_HEAD(&mos_parport->active_urbs);
    INIT_LIST_HEAD(&mos_parport->deferred_urbs);
    usb_set_serial_data(serial, mos_parport); /* hijack private pointer */
    mos_parport->serial = serial;
    tasklet_init(&mos_parport->urb_tasklet, send_deferred_urbs,
             (unsigned long) mos_parport);
    init_completion(&mos_parport->syncmsg_compl);

    /* cycle parallel port reset bit */
    write_mos_reg(mos_parport->serial, dummy, PP_REG, (__u8)0x80);
    write_mos_reg(mos_parport->serial, dummy, PP_REG, (__u8)0x00);

    /* initialize device registers */
    mos_parport->shadowDCR = DCR_INIT_VAL;
    write_mos_reg(mos_parport->serial, dummy, DCR, mos_parport->shadowDCR);
    mos_parport->shadowECR = ECR_INIT_VAL;
    write_mos_reg(mos_parport->serial, dummy, ECR, mos_parport->shadowECR);

    /* register with parport core */
    mos_parport->pp = parport_register_port(0, PARPORT_IRQ_NONE,
                        PARPORT_DMA_NONE,
                        &parport_mos7715_ops);
    if (mos_parport->pp == NULL) {
        dev_err(&serial->interface->dev,
            "Could not register parport\n");
        kref_put(&mos_parport->ref_count, destroy_mos_parport);
        return -EIO;
    }
    mos_parport->pp->private_data = mos_parport;
    mos_parport->pp->modes = PARPORT_MODE_COMPAT | PARPORT_MODE_PCSPP;
    mos_parport->pp->dev = &serial->interface->dev;
    parport_announce_port(mos_parport->pp);

    return 0;
}
#endif  /* CONFIG_USB_SERIAL_MOS7715_PARPORT */

/*
 * mos7720_interrupt_callback
 *  this is the callback function for when we have received data on the
 *  interrupt endpoint.
 */
static void mos7720_interrupt_callback(struct urb *urb)
{
    int result;
    int length;
    int status = urb->status;
    struct device *dev = &urb->dev->dev;
    __u8 *data;
    __u8 sp1;
    __u8 sp2;

    switch (status) {
    case 0:
        /* success */
        break;
    case -ECONNRESET:
    case -ENOENT:
    case -ESHUTDOWN:
        /* this urb is terminated, clean up */
        dev_dbg(dev, "%s - urb shutting down with status: %d\n", __func__, status);
        return;
    default:
        dev_dbg(dev, "%s - nonzero urb status received: %d\n", __func__, status);
        goto exit;
    }

    length = urb->actual_length;
    data = urb->transfer_buffer;

    /* Moschip get 4 bytes
     * Byte 1 IIR Port 1 (port.number is 0)
     * Byte 2 IIR Port 2 (port.number is 1)
     * Byte 3 --------------
     * Byte 4 FIFO status for both */

    /* the above description is inverted
     *  oneukum 2007-03-14 */

    if (unlikely(length != 4)) {
        dev_dbg(dev, "Wrong data !!!\n");
        return;
    }

    sp1 = data[3];
    sp2 = data[2];

    if ((sp1 | sp2) & 0x01) {
        /* No Interrupt Pending in both the ports */
        dev_dbg(dev, "No Interrupt !!!\n");
    } else {
        switch (sp1 & 0x0f) {
        case SERIAL_IIR_RLS:
            dev_dbg(dev, "Serial Port 1: Receiver status error or address bit detected in 9-bit mode\n");
            break;
        case SERIAL_IIR_CTI:
            dev_dbg(dev, "Serial Port 1: Receiver time out\n");
            break;
        case SERIAL_IIR_MS:
            /* dev_dbg(dev, "Serial Port 1: Modem status change\n"); */
            break;
        }

        switch (sp2 & 0x0f) {
        case SERIAL_IIR_RLS:
            dev_dbg(dev, "Serial Port 2: Receiver status error or address bit detected in 9-bit mode\n");
            break;
        case SERIAL_IIR_CTI:
            dev_dbg(dev, "Serial Port 2: Receiver time out\n");
            break;
        case SERIAL_IIR_MS:
            /* dev_dbg(dev, "Serial Port 2: Modem status change\n"); */
            break;
        }
    }

exit:
    result = usb_submit_urb(urb, GFP_ATOMIC);
    if (result)
        dev_err(dev, "%s - Error %d submitting control urb\n", __func__, result);
}

/*
 * mos7715_interrupt_callback
 *  this is the 7715's callback function for when we have received data on
 *  the interrupt endpoint.
 */
static void mos7715_interrupt_callback(struct urb *urb)
{
    int result;
    int length;
    int status = urb->status;
    struct device *dev = &urb->dev->dev;
    __u8 *data;
    __u8 iir;

    switch (status) {
    case 0:
        /* success */
        break;
    case -ECONNRESET:
    case -ENOENT:
    case -ESHUTDOWN:
    case -ENODEV:
        /* this urb is terminated, clean up */
        dev_dbg(dev, "%s - urb shutting down with status: %d\n", __func__, status);
        return;
    default:
        dev_dbg(dev, "%s - nonzero urb status received: %d\n", __func__, status);
        goto exit;
    }

    length = urb->actual_length;
    data = urb->transfer_buffer;

    /* Structure of data from 7715 device:
     * Byte 1: IIR serial Port
     * Byte 2: unused
     * Byte 2: DSR parallel port
     * Byte 4: FIFO status for both */

    if (unlikely(length != 4)) {
        dev_dbg(dev, "Wrong data !!!\n");
        return;
    }

    iir = data[0];
    if (!(iir & 0x01)) {    /* serial port interrupt pending */
        switch (iir & 0x0f) {
        case SERIAL_IIR_RLS:
            dev_dbg(dev, "Serial Port: Receiver status error or address bit detected in 9-bit mode\n\n");
            break;
        case SERIAL_IIR_CTI:
            dev_dbg(dev, "Serial Port: Receiver time out\n");
            break;
        case SERIAL_IIR_MS:
            /* dev_dbg(dev, "Serial Port: Modem status change\n"); */
            break;
        }
    }

#ifdef CONFIG_USB_SERIAL_MOS7715_PARPORT
    {       /* update local copy of DSR reg */
        struct usb_serial_port *port = urb->context;
        struct mos7715_parport *mos_parport = port->serial->private;
        if (unlikely(mos_parport == NULL))
            return;
        atomic_set(&mos_parport->shadowDSR, data[2]);
    }
#endif

exit:
    result = usb_submit_urb(urb, GFP_ATOMIC);
    if (result)
        dev_err(dev, "%s - Error %d submitting control urb\n", __func__, result);
}

/*
 * mos7720_bulk_in_callback
 *  this is the callback function for when we have received data on the
 *  bulk in endpoint.
 */
static void mos7720_bulk_in_callback(struct urb *urb)
{
    int retval;
    unsigned char *data ;
    struct usb_serial_port *port;
    struct tty_struct *tty;
    int status = urb->status;

    if (status) {
        dev_dbg(&urb->dev->dev, "nonzero read bulk status received: %d\n", status);
        return;
    }

    port = urb->context;

    dev_dbg(&port->dev, "Entering...%s\n", __func__);

    data = urb->transfer_buffer;

    tty = tty_port_tty_get(&port->port);
    if (tty && urb->actual_length) {
        tty_insert_flip_string(tty, data, urb->actual_length);
        tty_flip_buffer_push(tty);
    }
    tty_kref_put(tty);

    if (port->read_urb->status != -EINPROGRESS) {
        retval = usb_submit_urb(port->read_urb, GFP_ATOMIC);
        if (retval)
            dev_dbg(&port->dev, "usb_submit_urb(read bulk) failed, retval = %d\n", retval);
    }
}

/*
 * mos7720_bulk_out_data_callback
 *  this is the callback function for when we have finished sending serial
 *  data on the bulk out endpoint.
 */
static void mos7720_bulk_out_data_callback(struct urb *urb)
{
    struct moschip_port *mos7720_port;
    struct tty_struct *tty;
    int status = urb->status;

    if (status) {
        dev_dbg(&urb->dev->dev, "nonzero write bulk status received:%d\n", status);
        return;
    }

    mos7720_port = urb->context;
    if (!mos7720_port) {
        dev_dbg(&urb->dev->dev, "NULL mos7720_port pointer\n");
        return ;
    }

    tty = tty_port_tty_get(&mos7720_port->port->port);

    if (tty && mos7720_port->open)
        tty_wakeup(tty);
    tty_kref_put(tty);
}

/*
 * mos77xx_probe
 *  this function installs the appropriate read interrupt endpoint callback
 *  depending on whether the device is a 7720 or 7715, thus avoiding costly
 *  run-time checks in the high-frequency callback routine itself.
 */
static int mos77xx_probe(struct usb_serial *serial,
             const struct usb_device_id *id)
{
    if (id->idProduct == MOSCHIP_DEVICE_ID_7715)
        moschip7720_2port_driver.read_int_callback =
            mos7715_interrupt_callback;
    else
        moschip7720_2port_driver.read_int_callback =
            mos7720_interrupt_callback;

    return 0;
}

static int mos77xx_calc_num_ports(struct usb_serial *serial)
{
    u16 product = le16_to_cpu(serial->dev->descriptor.idProduct);
    if (product == MOSCHIP_DEVICE_ID_7715)
        return 1;

    return 2;
}

static int mos7720_open(struct tty_struct *tty, struct usb_serial_port *port)
{
    struct usb_serial *serial;
    struct urb *urb;
    struct moschip_port *mos7720_port;
    int response;
    int port_number;
    __u8 data;
    int allocated_urbs = 0;
    int j;

    serial = port->serial;

    mos7720_port = usb_get_serial_port_data(port);
    if (mos7720_port == NULL)
        return -ENODEV;

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

    /* Initialising the write urb pool */
    for (j = 0; j < NUM_URBS; ++j) {
        urb = usb_alloc_urb(0, GFP_KERNEL);
        mos7720_port->write_urb_pool[j] = urb;

        if (urb == NULL) {
            dev_err(&port->dev, "No more urbs???\n");
            continue;
        }

        urb->transfer_buffer = kmalloc(URB_TRANSFER_BUFFER_SIZE,
                           GFP_KERNEL);
        if (!urb->transfer_buffer) {
            dev_err(&port->dev,
                "%s-out of memory for urb buffers.\n",
                __func__);
            usb_free_urb(mos7720_port->write_urb_pool[j]);
            mos7720_port->write_urb_pool[j] = NULL;
            continue;
        }
        allocated_urbs++;
    }

    if (!allocated_urbs)
        return -ENOMEM;

     /* Initialize MCS7720 -- Write Init values to corresponding Registers
      *
      * Register Index
      * 0 : THR/RHR
      * 1 : IER
      * 2 : FCR
      * 3 : LCR
      * 4 : MCR
      * 5 : LSR
      * 6 : MSR
      * 7 : SPR
      *
      * 0x08 : SP1/2 Control Reg
      */
    port_number = port->number - port->serial->minor;
    read_mos_reg(serial, port_number, LSR, &data);

    dev_dbg(&port->dev, "SS::%p LSR:%x\n", mos7720_port, data);

    write_mos_reg(serial, dummy, SP1_REG, 0x02);
    write_mos_reg(serial, dummy, SP2_REG, 0x02);

    write_mos_reg(serial, port_number, IER, 0x00);
    write_mos_reg(serial, port_number, FCR, 0x00);

    write_mos_reg(serial, port_number, FCR, 0xcf);
    mos7720_port->shadowLCR = 0x03;
    write_mos_reg(serial, port_number, LCR, mos7720_port->shadowLCR);
    mos7720_port->shadowMCR = 0x0b;
    write_mos_reg(serial, port_number, MCR, mos7720_port->shadowMCR);

    write_mos_reg(serial, port_number, SP_CONTROL_REG, 0x00);
    read_mos_reg(serial, dummy, SP_CONTROL_REG, &data);
    data = data | (port->number - port->serial->minor + 1);
    write_mos_reg(serial, dummy, SP_CONTROL_REG, data);
    mos7720_port->shadowLCR = 0x83;
    write_mos_reg(serial, port_number, LCR, mos7720_port->shadowLCR);
    write_mos_reg(serial, port_number, THR, 0x0c);
    write_mos_reg(serial, port_number, IER, 0x00);
    mos7720_port->shadowLCR = 0x03;
    write_mos_reg(serial, port_number, LCR, mos7720_port->shadowLCR);
    write_mos_reg(serial, port_number, IER, 0x0c);

    response = usb_submit_urb(port->read_urb, GFP_KERNEL);
    if (response)
        dev_err(&port->dev, "%s - Error %d submitting read urb\n",
                            __func__, response);

    /* initialize our icount structure */
    memset(&(mos7720_port->icount), 0x00, sizeof(mos7720_port->icount));

    /* initialize our port settings */
    mos7720_port->shadowMCR = UART_MCR_OUT2; /* Must set to enable ints! */

    /* send a open port command */
    mos7720_port->open = 1;

    return 0;
}

/*
 * mos7720_chars_in_buffer
 *  this function is called by the tty driver when it wants to know how many
 *  bytes of data we currently have outstanding in the port (data that has
 *  been written, but hasn't made it out the port yet)
 *  If successful, we return the number of bytes left to be written in the
 *  system,
 *  Otherwise we return a negative error number.
 */
static int mos7720_chars_in_buffer(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    int i;
    int chars = 0;
    struct moschip_port *mos7720_port;

    mos7720_port = usb_get_serial_port_data(port);
    if (mos7720_port == NULL)
        return 0;

    for (i = 0; i < NUM_URBS; ++i) {
        if (mos7720_port->write_urb_pool[i] &&
            mos7720_port->write_urb_pool[i]->status == -EINPROGRESS)
            chars += URB_TRANSFER_BUFFER_SIZE;
    }
    dev_dbg(&port->dev, "%s - returns %d\n", __func__, chars);
    return chars;
}

static void mos7720_close(struct usb_serial_port *port)
{
    struct usb_serial *serial;
    struct moschip_port *mos7720_port;
    int j;

    serial = port->serial;

    mos7720_port = usb_get_serial_port_data(port);
    if (mos7720_port == NULL)
        return;

    for (j = 0; j < NUM_URBS; ++j)
        usb_kill_urb(mos7720_port->write_urb_pool[j]);

    /* Freeing Write URBs */
    for (j = 0; j < NUM_URBS; ++j) {
        if (mos7720_port->write_urb_pool[j]) {
            kfree(mos7720_port->write_urb_pool[j]->transfer_buffer);
            usb_free_urb(mos7720_port->write_urb_pool[j]);
        }
    }

    /* While closing port, shutdown all bulk read, write  *
     * and interrupt read if they exists, otherwise nop   */
    usb_kill_urb(port->write_urb);
    usb_kill_urb(port->read_urb);

    mutex_lock(&serial->disc_mutex);
    /* these commands must not be issued if the device has
     * been disconnected */
    if (!serial->disconnected) {
        write_mos_reg(serial, port->number - port->serial->minor,
                  MCR, 0x00);
        write_mos_reg(serial, port->number - port->serial->minor,
                  IER, 0x00);
    }
    mutex_unlock(&serial->disc_mutex);
    mos7720_port->open = 0;
}

static void mos7720_break(struct tty_struct *tty, int break_state)
{
    struct usb_serial_port *port = tty->driver_data;
    unsigned char data;
    struct usb_serial *serial;
    struct moschip_port *mos7720_port;

    serial = port->serial;

    mos7720_port = usb_get_serial_port_data(port);
    if (mos7720_port == NULL)
        return;

    if (break_state == -1)
        data = mos7720_port->shadowLCR | UART_LCR_SBC;
    else
        data = mos7720_port->shadowLCR & ~UART_LCR_SBC;

    mos7720_port->shadowLCR  = data;
    write_mos_reg(serial, port->number - port->serial->minor,
              LCR, mos7720_port->shadowLCR);
}

/*
 * mos7720_write_room
 *  this function is called by the tty driver when it wants to know how many
 *  bytes of data we can accept for a specific port.
 *  If successful, we return the amount of room that we have for this port
 *  Otherwise we return a negative error number.
 */
static int mos7720_write_room(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    struct moschip_port *mos7720_port;
    int room = 0;
    int i;

    mos7720_port = usb_get_serial_port_data(port);
    if (mos7720_port == NULL)
        return -ENODEV;

    /* FIXME: Locking */
    for (i = 0; i < NUM_URBS; ++i) {
        if (mos7720_port->write_urb_pool[i] &&
            mos7720_port->write_urb_pool[i]->status != -EINPROGRESS)
            room += URB_TRANSFER_BUFFER_SIZE;
    }

    dev_dbg(&port->dev, "%s - returns %d\n", __func__, room);
    return room;
}

static int mos7720_write(struct tty_struct *tty, struct usb_serial_port *port,
                 const unsigned char *data, int count)
{
    int status;
    int i;
    int bytes_sent = 0;
    int transfer_size;

    struct moschip_port *mos7720_port;
    struct usb_serial *serial;
    struct urb    *urb;
    const unsigned char *current_position = data;

    serial = port->serial;

    mos7720_port = usb_get_serial_port_data(port);
    if (mos7720_port == NULL)
        return -ENODEV;

    /* try to find a free urb in the list */
    urb = NULL;

    for (i = 0; i < NUM_URBS; ++i) {
        if (mos7720_port->write_urb_pool[i] &&
            mos7720_port->write_urb_pool[i]->status != -EINPROGRESS) {
            urb = mos7720_port->write_urb_pool[i];
            dev_dbg(&port->dev, "URB:%d\n", i);
            break;
        }
    }

    if (urb == NULL) {
        dev_dbg(&port->dev, "%s - no more free urbs\n", __func__);
        goto exit;
    }

    if (urb->transfer_buffer == NULL) {
        urb->transfer_buffer = kmalloc(URB_TRANSFER_BUFFER_SIZE,
                           GFP_KERNEL);
        if (urb->transfer_buffer == NULL) {
            dev_err_console(port, "%s no more kernel memory...\n",
                __func__);
            goto exit;
        }
    }
    transfer_size = min(count, URB_TRANSFER_BUFFER_SIZE);

    memcpy(urb->transfer_buffer, current_position, transfer_size);
    usb_serial_debug_data(&port->dev, __func__, transfer_size,
                  urb->transfer_buffer);

    /* fill urb with data and submit  */
    usb_fill_bulk_urb(urb, serial->dev,
              usb_sndbulkpipe(serial->dev,
                    port->bulk_out_endpointAddress),
              urb->transfer_buffer, transfer_size,
              mos7720_bulk_out_data_callback, mos7720_port);

    /* send it down the pipe */
    status = usb_submit_urb(urb, GFP_ATOMIC);
    if (status) {
        dev_err_console(port, "%s - usb_submit_urb(write bulk) failed "
            "with status = %d\n", __func__, status);
        bytes_sent = status;
        goto exit;
    }
    bytes_sent = transfer_size;

exit:
    return bytes_sent;
}

static void mos7720_throttle(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    struct moschip_port *mos7720_port;
    int status;

    mos7720_port = usb_get_serial_port_data(port);

    if (mos7720_port == NULL)
        return;

    if (!mos7720_port->open) {
        dev_dbg(&port->dev, "%s - port not opened\n", __func__);
        return;
    }

    /* if we are implementing XON/XOFF, send the stop character */
    if (I_IXOFF(tty)) {
        unsigned char stop_char = STOP_CHAR(tty);
        status = mos7720_write(tty, port, &stop_char, 1);
        if (status <= 0)
            return;
    }

    /* if we are implementing RTS/CTS, toggle that line */
    if (tty->termios.c_cflag & CRTSCTS) {
        mos7720_port->shadowMCR &= ~UART_MCR_RTS;
        write_mos_reg(port->serial, port->number - port->serial->minor,
                  MCR, mos7720_port->shadowMCR);
        if (status != 0)
            return;
    }
}

static void mos7720_unthrottle(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    struct moschip_port *mos7720_port = usb_get_serial_port_data(port);
    int status;

    if (mos7720_port == NULL)
        return;

    if (!mos7720_port->open) {
        dev_dbg(&port->dev, "%s - port not opened\n", __func__);
        return;
    }

    /* if we are implementing XON/XOFF, send the start character */
    if (I_IXOFF(tty)) {
        unsigned char start_char = START_CHAR(tty);
        status = mos7720_write(tty, port, &start_char, 1);
        if (status <= 0)
            return;
    }

    /* if we are implementing RTS/CTS, toggle that line */
    if (tty->termios.c_cflag & CRTSCTS) {
        mos7720_port->shadowMCR |= UART_MCR_RTS;
        write_mos_reg(port->serial, port->number - port->serial->minor,
                  MCR, mos7720_port->shadowMCR);
        if (status != 0)
            return;
    }
}

/* FIXME: this function does not work */
static int set_higher_rates(struct moschip_port *mos7720_port,
                unsigned int baud)
{
    struct usb_serial_port *port;
    struct usb_serial *serial;
    int port_number;
    enum mos_regs sp_reg;
    if (mos7720_port == NULL)
        return -EINVAL;

    port = mos7720_port->port;
    serial = port->serial;

     /***********************************************
     *      Init Sequence for higher rates
     ***********************************************/
    dev_dbg(&port->dev, "Sending Setting Commands ..........\n");
    port_number = port->number - port->serial->minor;

    write_mos_reg(serial, port_number, IER, 0x00);
    write_mos_reg(serial, port_number, FCR, 0x00);
    write_mos_reg(serial, port_number, FCR, 0xcf);
    mos7720_port->shadowMCR = 0x0b;
    write_mos_reg(serial, port_number, MCR, mos7720_port->shadowMCR);
    write_mos_reg(serial, dummy, SP_CONTROL_REG, 0x00);

    /***********************************************
     *              Set for higher rates           *
     ***********************************************/
    /* writing baud rate verbatum into uart clock field clearly not right */
    if (port_number == 0)
        sp_reg = SP1_REG;
    else
        sp_reg = SP2_REG;
    write_mos_reg(serial, dummy, sp_reg, baud * 0x10);
    write_mos_reg(serial, dummy, SP_CONTROL_REG, 0x03);
    mos7720_port->shadowMCR = 0x2b;
    write_mos_reg(serial, port_number, MCR, mos7720_port->shadowMCR);

    /***********************************************
     *              Set DLL/DLM
     ***********************************************/
    mos7720_port->shadowLCR = mos7720_port->shadowLCR | UART_LCR_DLAB;
    write_mos_reg(serial, port_number, LCR, mos7720_port->shadowLCR);
    write_mos_reg(serial, port_number, DLL, 0x01);
    write_mos_reg(serial, port_number, DLM, 0x00);
    mos7720_port->shadowLCR = mos7720_port->shadowLCR & ~UART_LCR_DLAB;
    write_mos_reg(serial, port_number, LCR, mos7720_port->shadowLCR);

    return 0;
}

/* baud rate information */
struct divisor_table_entry {
    __u32  baudrate;
    __u16  divisor;
};

/* Define table of divisors for moschip 7720 hardware      *
 * These assume a 3.6864MHz crystal, the standard /16, and *
 * MCR.7 = 0.                          */
static struct divisor_table_entry divisor_table[] = {
    {   50,     2304},
    {   110,    1047},  /* 2094.545455 => 230450   => .0217 % over */
    {   134,    857},   /* 1713.011152 => 230398.5 => .00065% under */
    {   150,    768},
    {   300,    384},
    {   600,    192},
    {   1200,   96},
    {   1800,   64},
    {   2400,   48},
    {   4800,   24},
    {   7200,   16},
    {   9600,   12},
    {   19200,  6},
    {   38400,  3},
    {   57600,  2},
    {   115200, 1},
};

/*****************************************************************************
 * calc_baud_rate_divisor
 *  this function calculates the proper baud rate divisor for the specified
 *  baud rate.
 *****************************************************************************/
static int calc_baud_rate_divisor(struct usb_serial_port *port, int baudrate, int *divisor)
{
    int i;
    __u16 custom;
    __u16 round1;
    __u16 round;


    dev_dbg(&port->dev, "%s - %d\n", __func__, baudrate);

    for (i = 0; i < ARRAY_SIZE(divisor_table); i++) {
        if (divisor_table[i].baudrate == baudrate) {
            *divisor = divisor_table[i].divisor;
            return 0;
        }
    }

    /* After trying for all the standard baud rates    *
     * Try calculating the divisor for this baud rate  */
    if (baudrate > 75 &&  baudrate < 230400) {
        /* get the divisor */
        custom = (__u16)(230400L  / baudrate);

        /* Check for round off */
        round1 = (__u16)(2304000L / baudrate);
        round = (__u16)(round1 - (custom * 10));
        if (round > 4)
            custom++;
        *divisor = custom;

        dev_dbg(&port->dev, "Baud %d = %d\n", baudrate, custom);
        return 0;
    }

    dev_dbg(&port->dev, "Baud calculation Failed...\n");
    return -EINVAL;
}

/*
 * send_cmd_write_baud_rate
 *  this function sends the proper command to change the baud rate of the
 *  specified port.
 */
static int send_cmd_write_baud_rate(struct moschip_port *mos7720_port,
                    int baudrate)
{
    struct usb_serial_port *port;
    struct usb_serial *serial;
    int divisor;
    int status;
    unsigned char number;

    if (mos7720_port == NULL)
        return -1;

    port = mos7720_port->port;
    serial = port->serial;

    number = port->number - port->serial->minor;
    dev_dbg(&port->dev, "%s - baud = %d\n", __func__, baudrate);

    /* Calculate the Divisor */
    status = calc_baud_rate_divisor(port, baudrate, &divisor);
    if (status) {
        dev_err(&port->dev, "%s - bad baud rate\n", __func__);
        return status;
    }

    /* Enable access to divisor latch */
    mos7720_port->shadowLCR = mos7720_port->shadowLCR | UART_LCR_DLAB;
    write_mos_reg(serial, number, LCR, mos7720_port->shadowLCR);

    /* Write the divisor */
    write_mos_reg(serial, number, DLL, (__u8)(divisor & 0xff));
    write_mos_reg(serial, number, DLM, (__u8)((divisor & 0xff00) >> 8));

    /* Disable access to divisor latch */
    mos7720_port->shadowLCR = mos7720_port->shadowLCR & ~UART_LCR_DLAB;
    write_mos_reg(serial, number, LCR, mos7720_port->shadowLCR);

    return status;
}

/*
 * change_port_settings
 *  This routine is called to set the UART on the device to match
 *      the specified new settings.
 */
static void change_port_settings(struct tty_struct *tty,
                 struct moschip_port *mos7720_port,
                 struct ktermios *old_termios)
{
    struct usb_serial_port *port;
    struct usb_serial *serial;
    int baud;
    unsigned cflag;
    unsigned iflag;
    __u8 mask = 0xff;
    __u8 lData;
    __u8 lParity;
    __u8 lStop;
    int status;
    int port_number;

    if (mos7720_port == NULL)
        return ;

    port = mos7720_port->port;
    serial = port->serial;
    port_number = port->number - port->serial->minor;

    if (!mos7720_port->open) {
        dev_dbg(&port->dev, "%s - port not opened\n", __func__);
        return;
    }

    lData = UART_LCR_WLEN8;
    lStop = 0x00;   /* 1 stop bit */
    lParity = 0x00; /* No parity */

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

    /* Change the number of bits */
    switch (cflag & CSIZE) {
    case CS5:
        lData = UART_LCR_WLEN5;
        mask = 0x1f;
        break;

    case CS6:
        lData = UART_LCR_WLEN6;
        mask = 0x3f;
        break;

    case CS7:
        lData = UART_LCR_WLEN7;
        mask = 0x7f;
        break;
    default:
    case CS8:
        lData = UART_LCR_WLEN8;
        break;
    }

    /* Change the Parity bit */
    if (cflag & PARENB) {
        if (cflag & PARODD) {
            lParity = UART_LCR_PARITY;
            dev_dbg(&port->dev, "%s - parity = odd\n", __func__);
        } else {
            lParity = (UART_LCR_EPAR | UART_LCR_PARITY);
            dev_dbg(&port->dev, "%s - parity = even\n", __func__);
        }

    } else {
        dev_dbg(&port->dev, "%s - parity = none\n", __func__);
    }

    if (cflag & CMSPAR)
        lParity = lParity | 0x20;

    /* Change the Stop bit */
    if (cflag & CSTOPB) {
        lStop = UART_LCR_STOP;
        dev_dbg(&port->dev, "%s - stop bits = 2\n", __func__);
    } else {
        lStop = 0x00;
        dev_dbg(&port->dev, "%s - stop bits = 1\n", __func__);
    }

#define LCR_BITS_MASK       0x03    /* Mask for bits/char field */
#define LCR_STOP_MASK       0x04    /* Mask for stop bits field */
#define LCR_PAR_MASK        0x38    /* Mask for parity field */

    /* Update the LCR with the correct value */
    mos7720_port->shadowLCR &=
        ~(LCR_BITS_MASK | LCR_STOP_MASK | LCR_PAR_MASK);
    mos7720_port->shadowLCR |= (lData | lParity | lStop);


    /* Disable Interrupts */
    write_mos_reg(serial, port_number, IER, 0x00);
    write_mos_reg(serial, port_number, FCR, 0x00);
    write_mos_reg(serial, port_number, FCR, 0xcf);

    /* Send the updated LCR value to the mos7720 */
    write_mos_reg(serial, port_number, LCR, mos7720_port->shadowLCR);
    mos7720_port->shadowMCR = 0x0b;
    write_mos_reg(serial, port_number, MCR, mos7720_port->shadowMCR);

    /* set up the MCR register and send it to the mos7720 */
    mos7720_port->shadowMCR = UART_MCR_OUT2;
    if (cflag & CBAUD)
        mos7720_port->shadowMCR |= (UART_MCR_DTR | UART_MCR_RTS);

    if (cflag & CRTSCTS) {
        mos7720_port->shadowMCR |= (UART_MCR_XONANY);
        /* To set hardware flow control to the specified *
         * serial port, in SP1/2_CONTROL_REG             */
        if (port->number)
            write_mos_reg(serial, dummy, SP_CONTROL_REG, 0x01);
        else
            write_mos_reg(serial, dummy, SP_CONTROL_REG, 0x02);

    } else
        mos7720_port->shadowMCR &= ~(UART_MCR_XONANY);

    write_mos_reg(serial, port_number, MCR, mos7720_port->shadowMCR);

    /* Determine divisor based on baud rate */
    baud = tty_get_baud_rate(tty);
    if (!baud) {
        /* pick a default, any default... */
        dev_dbg(&port->dev, "Picked default baud...\n");
        baud = 9600;
    }

    if (baud >= 230400) {
        set_higher_rates(mos7720_port, baud);
        /* Enable Interrupts */
        write_mos_reg(serial, port_number, IER, 0x0c);
        return;
    }

    dev_dbg(&port->dev, "%s - baud rate = %d\n", __func__, baud);
    status = send_cmd_write_baud_rate(mos7720_port, baud);
    /* FIXME: needs to write actual resulting baud back not just
       blindly do so */
    if (cflag & CBAUD)
        tty_encode_baud_rate(tty, baud, baud);
    /* Enable Interrupts */
    write_mos_reg(serial, port_number, IER, 0x0c);

    if (port->read_urb->status != -EINPROGRESS) {
        status = usb_submit_urb(port->read_urb, GFP_ATOMIC);
        if (status)
            dev_dbg(&port->dev, "usb_submit_urb(read bulk) failed, status = %d\n", status);
    }
}

/*
 * mos7720_set_termios
 *  this function is called by the tty driver when it wants to change the
 *  termios structure.
 */
static void mos7720_set_termios(struct tty_struct *tty,
        struct usb_serial_port *port, struct ktermios *old_termios)
{
    int status;
    unsigned int cflag;
    struct usb_serial *serial;
    struct moschip_port *mos7720_port;

    serial = port->serial;

    mos7720_port = usb_get_serial_port_data(port);

    if (mos7720_port == NULL)
        return;

    if (!mos7720_port->open) {
        dev_dbg(&port->dev, "%s - port not opened\n", __func__);
        return;
    }

    dev_dbg(&port->dev, "setting termios - ASPIRE\n");

    cflag = tty->termios.c_cflag;

    dev_dbg(&port->dev, "%s - cflag %08x iflag %08x\n", __func__,
        tty->termios.c_cflag, RELEVANT_IFLAG(tty->termios.c_iflag));

    dev_dbg(&port->dev, "%s - old cflag %08x old iflag %08x\n", __func__,
        old_termios->c_cflag, RELEVANT_IFLAG(old_termios->c_iflag));

    /* change the port settings to the new ones specified */
    change_port_settings(tty, mos7720_port, old_termios);

    if (port->read_urb->status != -EINPROGRESS) {
        status = usb_submit_urb(port->read_urb, GFP_ATOMIC);
        if (status)
            dev_dbg(&port->dev, "usb_submit_urb(read bulk) failed, status = %d\n", status);
    }
}

/*
 * get_lsr_info - get line status register info
 *
 * Purpose: Let user call ioctl() to get info when the UART physically
 *      is emptied.  On bus types like RS485, the transmitter must
 *      release the bus after transmitting. This must be done when
 *      the transmit shift register is empty, not be done when the
 *      transmit holding register is empty.  This functionality
 *      allows an RS485 driver to be written in user space.
 */
static int get_lsr_info(struct tty_struct *tty,
        struct moschip_port *mos7720_port, unsigned int __user *value)
{
    struct usb_serial_port *port = tty->driver_data;
    unsigned int result = 0;
    unsigned char data = 0;
    int port_number = port->number - port->serial->minor;
    int count;

    count = mos7720_chars_in_buffer(tty);
    if (count == 0) {
        read_mos_reg(port->serial, port_number, LSR, &data);
        if ((data & (UART_LSR_TEMT | UART_LSR_THRE))
                    == (UART_LSR_TEMT | UART_LSR_THRE)) {
            dev_dbg(&port->dev, "%s -- Empty\n", __func__);
            result = TIOCSER_TEMT;
        }
    }
    if (copy_to_user(value, &result, sizeof(int)))
        return -EFAULT;
    return 0;
}

static int mos7720_tiocmget(struct tty_struct *tty)
{
    struct usb_serial_port *port = tty->driver_data;
    struct moschip_port *mos7720_port = usb_get_serial_port_data(port);
    unsigned int result = 0;
    unsigned int mcr ;
    unsigned int msr ;

    mcr = mos7720_port->shadowMCR;
    msr = mos7720_port->shadowMSR;

    result = ((mcr & UART_MCR_DTR)  ? TIOCM_DTR : 0)   /* 0x002 */
      | ((mcr & UART_MCR_RTS)   ? TIOCM_RTS : 0)   /* 0x004 */
      | ((msr & UART_MSR_CTS)   ? TIOCM_CTS : 0)   /* 0x020 */
      | ((msr & UART_MSR_DCD)   ? TIOCM_CAR : 0)   /* 0x040 */
      | ((msr & UART_MSR_RI)    ? TIOCM_RI :  0)   /* 0x080 */
      | ((msr & UART_MSR_DSR)   ? TIOCM_DSR : 0);  /* 0x100 */

    return result;
}

static int mos7720_tiocmset(struct tty_struct *tty,
                unsigned int set, unsigned int clear)
{
    struct usb_serial_port *port = tty->driver_data;
    struct moschip_port *mos7720_port = usb_get_serial_port_data(port);
    unsigned int mcr ;

    mcr = mos7720_port->shadowMCR;

    if (set & TIOCM_RTS)
        mcr |= UART_MCR_RTS;
    if (set & TIOCM_DTR)
        mcr |= UART_MCR_DTR;
    if (set & TIOCM_LOOP)
        mcr |= UART_MCR_LOOP;

    if (clear & TIOCM_RTS)
        mcr &= ~UART_MCR_RTS;
    if (clear & TIOCM_DTR)
        mcr &= ~UART_MCR_DTR;
    if (clear & TIOCM_LOOP)
        mcr &= ~UART_MCR_LOOP;

    mos7720_port->shadowMCR = mcr;
    write_mos_reg(port->serial, port->number - port->serial->minor,
              MCR, mos7720_port->shadowMCR);

    return 0;
}

static int mos7720_get_icount(struct tty_struct *tty,
                struct serial_icounter_struct *icount)
{
    struct usb_serial_port *port = tty->driver_data;
    struct moschip_port *mos7720_port;
    struct async_icount cnow;

    mos7720_port = usb_get_serial_port_data(port);
    cnow = mos7720_port->icount;

    icount->cts = cnow.cts;
    icount->dsr = cnow.dsr;
    icount->rng = cnow.rng;
    icount->dcd = cnow.dcd;
    icount->rx = cnow.rx;
    icount->tx = cnow.tx;
    icount->frame = cnow.frame;
    icount->overrun = cnow.overrun;
    icount->parity = cnow.parity;
    icount->brk = cnow.brk;
    icount->buf_overrun = cnow.buf_overrun;

    dev_dbg(&port->dev, "%s TIOCGICOUNT RX=%d, TX=%d\n", __func__,
        icount->rx, icount->tx);
    return 0;
}

static int set_modem_info(struct moschip_port *mos7720_port, unsigned int cmd,
              unsigned int __user *value)
{
    unsigned int mcr;
    unsigned int arg;

    struct usb_serial_port *port;

    if (mos7720_port == NULL)
        return -1;

    port = (struct usb_serial_port *)mos7720_port->port;
    mcr = mos7720_port->shadowMCR;

    if (copy_from_user(&arg, value, sizeof(int)))
        return -EFAULT;

    switch (cmd) {
    case TIOCMBIS:
        if (arg & TIOCM_RTS)
            mcr |= UART_MCR_RTS;
        if (arg & TIOCM_DTR)
            mcr |= UART_MCR_RTS;
        if (arg & TIOCM_LOOP)
            mcr |= UART_MCR_LOOP;
        break;

    case TIOCMBIC:
        if (arg & TIOCM_RTS)
            mcr &= ~UART_MCR_RTS;
        if (arg & TIOCM_DTR)
            mcr &= ~UART_MCR_RTS;
        if (arg & TIOCM_LOOP)
            mcr &= ~UART_MCR_LOOP;
        break;

    }

    mos7720_port->shadowMCR = mcr;
    write_mos_reg(port->serial, port->number - port->serial->minor,
              MCR, mos7720_port->shadowMCR);

    return 0;
}

static int get_serial_info(struct moschip_port *mos7720_port,
               struct serial_struct __user *retinfo)
{
    struct serial_struct tmp;

    if (!retinfo)
        return -EFAULT;

    memset(&tmp, 0, sizeof(tmp));

    tmp.type        = PORT_16550A;
    tmp.line        = mos7720_port->port->serial->minor;
    tmp.port        = mos7720_port->port->number;
    tmp.irq         = 0;
    tmp.flags       = ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ;
    tmp.xmit_fifo_size  = NUM_URBS * URB_TRANSFER_BUFFER_SIZE;
    tmp.baud_base       = 9600;
    tmp.close_delay     = 5*HZ;
    tmp.closing_wait    = 30*HZ;

    if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
        return -EFAULT;
    return 0;
}

static int mos7720_ioctl(struct tty_struct *tty,
             unsigned int cmd, unsigned long arg)
{
    struct usb_serial_port *port = tty->driver_data;
    struct moschip_port *mos7720_port;
    struct async_icount cnow;
    struct async_icount cprev;

    mos7720_port = usb_get_serial_port_data(port);
    if (mos7720_port == NULL)
        return -ENODEV;

    dev_dbg(&port->dev, "%s - cmd = 0x%x", __func__, cmd);

    switch (cmd) {
    case TIOCSERGETLSR:
        dev_dbg(&port->dev, "%s TIOCSERGETLSR\n", __func__);
        return get_lsr_info(tty, mos7720_port,
                    (unsigned int __user *)arg);

    /* FIXME: These should be using the mode methods */
    case TIOCMBIS:
    case TIOCMBIC:
        dev_dbg(&port->dev, "%s TIOCMSET/TIOCMBIC/TIOCMSET\n", __func__);
        return set_modem_info(mos7720_port, cmd,
                      (unsigned int __user *)arg);

    case TIOCGSERIAL:
        dev_dbg(&port->dev, "%s TIOCGSERIAL\n", __func__);
        return get_serial_info(mos7720_port,
                       (struct serial_struct __user *)arg);

    case TIOCMIWAIT:
        dev_dbg(&port->dev, "%s TIOCMIWAIT\n", __func__);
        cprev = mos7720_port->icount;
        while (1) {
            if (signal_pending(current))
                return -ERESTARTSYS;
            cnow = mos7720_port->icount;
            if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
                cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
                return -EIO; /* no change => error */
            if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
                ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
                ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
                ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {
                return 0;
            }
            cprev = cnow;
        }
        /* NOTREACHED */
        break;
    }

    return -ENOIOCTLCMD;
}

static int mos7720_startup(struct usb_serial *serial)
{
    struct usb_device *dev;
    char data;
    u16 product;
    int ret_val;

    product = le16_to_cpu(serial->dev->descriptor.idProduct);
    dev = serial->dev;

    /*
     * The 7715 uses the first bulk in/out endpoint pair for the parallel
     * port, and the second for the serial port.  Because the usbserial core
     * assumes both pairs are serial ports, we must engage in a bit of
     * subterfuge and swap the pointers for ports 0 and 1 in order to make
     * port 0 point to the serial port.  However, both moschip devices use a
     * single interrupt-in endpoint for both ports (as mentioned a little
     * further down), and this endpoint was assigned to port 0.  So after
     * the swap, we must copy the interrupt endpoint elements from port 1
     * (as newly assigned) to port 0, and null out port 1 pointers.
     */
    if (product == MOSCHIP_DEVICE_ID_7715) {
        struct usb_serial_port *tmp = serial->port[0];
        serial->port[0] = serial->port[1];
        serial->port[1] = tmp;
        serial->port[0]->interrupt_in_urb = tmp->interrupt_in_urb;
        serial->port[0]->interrupt_in_buffer = tmp->interrupt_in_buffer;
        serial->port[0]->interrupt_in_endpointAddress =
            tmp->interrupt_in_endpointAddress;
        serial->port[1]->interrupt_in_urb = NULL;
        serial->port[1]->interrupt_in_buffer = NULL;
    }

    /* setting configuration feature to one */
    usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
            (__u8)0x03, 0x00, 0x01, 0x00, NULL, 0x00, 5*HZ);

    /* start the interrupt urb */
    ret_val = usb_submit_urb(serial->port[0]->interrupt_in_urb, GFP_KERNEL);
    if (ret_val)
        dev_err(&dev->dev,
            "%s - Error %d submitting control urb\n",
            __func__, ret_val);

#ifdef CONFIG_USB_SERIAL_MOS7715_PARPORT
    if (product == MOSCHIP_DEVICE_ID_7715) {
        ret_val = mos7715_parport_init(serial);
        if (ret_val < 0)
            return ret_val;
    }
#endif
    /* LSR For Port 1 */
    read_mos_reg(serial, 0, LSR, &data);
    dev_dbg(&dev->dev, "LSR:%x\n", data);

    return 0;
}

static void mos7720_release(struct usb_serial *serial)
{
#ifdef CONFIG_USB_SERIAL_MOS7715_PARPORT
    /* close the parallel port */

    if (le16_to_cpu(serial->dev->descriptor.idProduct)
        == MOSCHIP_DEVICE_ID_7715) {
        struct urbtracker *urbtrack;
        unsigned long flags;
        struct mos7715_parport *mos_parport =
            usb_get_serial_data(serial);

        /* prevent NULL ptr dereference in port callbacks */
        spin_lock(&release_lock);
        mos_parport->pp->private_data = NULL;
        spin_unlock(&release_lock);

        /* wait for synchronous usb calls to return */
        if (mos_parport->msg_pending)
            wait_for_completion_timeout(&mos_parport->syncmsg_compl,
                            MOS_WDR_TIMEOUT);

        parport_remove_port(mos_parport->pp);
        usb_set_serial_data(serial, NULL);
        mos_parport->serial = NULL;

        /* if tasklet currently scheduled, wait for it to complete */
        tasklet_kill(&mos_parport->urb_tasklet);

        /* unlink any urbs sent by the tasklet  */
        spin_lock_irqsave(&mos_parport->listlock, flags);
        list_for_each_entry(urbtrack,
                    &mos_parport->active_urbs,
                    urblist_entry)
            usb_unlink_urb(urbtrack->urb);
        spin_unlock_irqrestore(&mos_parport->listlock, flags);

        kref_put(&mos_parport->ref_count, destroy_mos_parport);
    }
#endif
}

static int mos7720_port_probe(struct usb_serial_port *port)
{
    struct moschip_port *mos7720_port;

    mos7720_port = kzalloc(sizeof(*mos7720_port), GFP_KERNEL);
    if (!mos7720_port)
        return -ENOMEM;

    /* Initialize all port interrupt end point to port 0 int endpoint.
     * Our device has only one interrupt endpoint common to all ports.
     */
    port->interrupt_in_endpointAddress =
        port->serial->port[0]->interrupt_in_endpointAddress;
    mos7720_port->port = port;

    usb_set_serial_port_data(port, mos7720_port);

    return 0;
}

static int mos7720_port_remove(struct usb_serial_port *port)
{
    struct moschip_port *mos7720_port;

    mos7720_port = usb_get_serial_port_data(port);
    kfree(mos7720_port);

    return 0;
}

static struct usb_serial_driver moschip7720_2port_driver = {
    .driver = {
        .owner =    THIS_MODULE,
        .name =     "moschip7720",
    },
    .description        = "Moschip 2 port adapter",
    .id_table       = id_table,
    .calc_num_ports     = mos77xx_calc_num_ports,
    .open           = mos7720_open,
    .close          = mos7720_close,
    .throttle       = mos7720_throttle,
    .unthrottle     = mos7720_unthrottle,
    .probe          = mos77xx_probe,
    .attach         = mos7720_startup,
    .release        = mos7720_release,
    .port_probe     = mos7720_port_probe,
    .port_remove        = mos7720_port_remove,
    .ioctl          = mos7720_ioctl,
    .tiocmget       = mos7720_tiocmget,
    .tiocmset       = mos7720_tiocmset,
    .get_icount     = mos7720_get_icount,
    .set_termios        = mos7720_set_termios,
    .write          = mos7720_write,
    .write_room     = mos7720_write_room,
    .chars_in_buffer    = mos7720_chars_in_buffer,
    .break_ctl      = mos7720_break,
    .read_bulk_callback = mos7720_bulk_in_callback,
    .read_int_callback  = NULL  /* dynamically assigned in probe() */
};

static struct usb_serial_driver * const serial_drivers[] = {
    &moschip7720_2port_driver, NULL
};

module_usb_serial_driver(serial_drivers, id_table);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");