/*

 
        Copyright (C) 1996  Digi International.
 
        For technical support please email digiLinux@dgii.com or
        call Digi tech support at (612) 912-3456

        Much of this design and code came from epca.c which was 
        copyright (C) 1994, 1995 Troy De Jongh, and subsquently 
        modified by David Nugent, Christoph Lameter, Mike McLagan. 
 
        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.

        This program is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        GNU General Public License for more details.

        You should have received a copy of the GNU General Public License
        along with this program; if not, write to the Free Software
        Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

--------------------------------------------------------------------------- */
/* See README.epca for change history --DAT*/


#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/serial.h>
#include <linux/delay.h>
#include <linux/ctype.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <asm/uaccess.h>
#include <asm/io.h>

#ifdef CONFIG_PCI
#define ENABLE_PCI
#endif /* CONFIG_PCI */

#define putUser(arg1, arg2) put_user(arg1, (unsigned long *)arg2)
#define getUser(arg1, arg2) get_user(arg1, (unsigned int *)arg2)

#ifdef ENABLE_PCI
#include <linux/pci.h>
#include "digiPCI.h"
#endif /* ENABLE_PCI */

#include "digi1.h"
#include "digiFep1.h"
#include "epca.h"
#include "epcaconfig.h"

#if BITS_PER_LONG != 32
#  error FIXME: this driver only works on 32-bit platforms
#endif

/* ---------------------- Begin defines ------------------------ */

#define VERSION            "1.3.0.1-LK"

/* This major needs to be submitted to Linux to join the majors list */

#define DIGIINFOMAJOR       35  /* For Digi specific ioctl */ 


#define MIN(a,b)        ((a) < (b) ? (a) : (b))
#define MAXCARDS 7
#define epcaassert(x, msg)  if (!(x)) epca_error(__LINE__, msg)

#define PFX "epca: "

/* ----------------- Begin global definitions ------------------- */

static char mesg[100];
static int pc_refcount, nbdevs, num_cards, liloconfig;
static int digi_poller_inhibited = 1 ;

static int setup_error_code;
static int invalid_lilo_config;

/* -----------------------------------------------------------------------
        MAXBOARDS is typically 12, but ISA and EISA cards are restricted to 
        7 below.
--------------------------------------------------------------------------*/
static struct board_info boards[MAXBOARDS];


/* ------------- Begin structures used for driver registeration ---------- */

struct tty_driver pc_driver;
struct tty_driver pc_callout;
struct tty_driver pc_info;

/* The below structures are used to initialize the tty_driver structures. */

/*      -------------------------------------------------------------------------
        Note : MAX_ALLOC is currently limited to 0x100.  This restriction is 
        placed on us by Linux not Digi.
----------------------------------------------------------------------------*/
static struct tty_struct *pc_table[MAX_ALLOC];
static struct termios *pc_termios[MAX_ALLOC];
static struct termios *pc_termios_locked[MAX_ALLOC];


/* ------------------ Begin Digi specific structures -------------------- */

/* ------------------------------------------------------------------------
        digi_channels represents an array of structures that keep track of
        each channel of the Digi product.  Information such as transmit and
        receive pointers, termio data, and signal definitions (DTR, CTS, etc ...)
        are stored here.  This structure is NOT used to overlay the cards 
        physical channel structure.
-------------------------------------------------------------------------- */
  
static struct channel digi_channels[MAX_ALLOC];

/* ------------------------------------------------------------------------
        card_ptr is an array used to hold the address of the
        first channel structure of each card.  This array will hold
        the addresses of various channels located in digi_channels.
-------------------------------------------------------------------------- */
static struct channel *card_ptr[MAXCARDS];

static struct timer_list epca_timer;

/* ---------------------- Begin function prototypes --------------------- */

/* ----------------------------------------------------------------------
        Begin generic memory functions.  These functions will be alias
        (point at) more specific functions dependent on the board being
        configured.
----------------------------------------------------------------------- */
        

#ifdef MODULE
int                init_module(void);
void               cleanup_module(void);
#endif /* MODULE */

static inline void memwinon(struct board_info *b, unsigned int win);
static inline void memwinoff(struct board_info *b, unsigned int win);
static inline void globalwinon(struct channel *ch);
static inline void rxwinon(struct channel *ch);
static inline void txwinon(struct channel *ch);
static inline void memoff(struct channel *ch);
static inline void assertgwinon(struct channel *ch);
static inline void assertmemoff(struct channel *ch);

/* ---- Begin more 'specific' memory functions for cx_like products --- */

static inline void pcxem_memwinon(struct board_info *b, unsigned int win);
static inline void pcxem_memwinoff(struct board_info *b, unsigned int win);
static inline void pcxem_globalwinon(struct channel *ch);
static inline void pcxem_rxwinon(struct channel *ch);
static inline void pcxem_txwinon(struct channel *ch);
static inline void pcxem_memoff(struct channel *ch);

/* ------ Begin more 'specific' memory functions for the pcxe ------- */

static inline void pcxe_memwinon(struct board_info *b, unsigned int win);
static inline void pcxe_memwinoff(struct board_info *b, unsigned int win);
static inline void pcxe_globalwinon(struct channel *ch);
static inline void pcxe_rxwinon(struct channel *ch);
static inline void pcxe_txwinon(struct channel *ch);
static inline void pcxe_memoff(struct channel *ch);

/* ---- Begin more 'specific' memory functions for the pc64xe and pcxi ---- */
/* Note : pc64xe and pcxi share the same windowing routines */

static inline void pcxi_memwinon(struct board_info *b, unsigned int win);
static inline void pcxi_memwinoff(struct board_info *b, unsigned int win);
static inline void pcxi_globalwinon(struct channel *ch);
static inline void pcxi_rxwinon(struct channel *ch);
static inline void pcxi_txwinon(struct channel *ch);
static inline void pcxi_memoff(struct channel *ch);

/* - Begin 'specific' do nothing memory functions needed for some cards - */

static inline void dummy_memwinon(struct board_info *b, unsigned int win);
static inline void dummy_memwinoff(struct board_info *b, unsigned int win);
static inline void dummy_globalwinon(struct channel *ch);
static inline void dummy_rxwinon(struct channel *ch);
static inline void dummy_txwinon(struct channel *ch);
static inline void dummy_memoff(struct channel *ch);
static inline void dummy_assertgwinon(struct channel *ch);
static inline void dummy_assertmemoff(struct channel *ch);

/* ------------------- Begin declare functions ----------------------- */

static inline struct channel *verifyChannel(register struct tty_struct *);
static inline void pc_sched_event(struct channel *, int);
static void epca_error(int, char *);
static void pc_close(struct tty_struct *, struct file *);
static void shutdown(struct channel *);
static void pc_hangup(struct tty_struct *);
static void pc_put_char(struct tty_struct *, unsigned char);
static int pc_write_room(struct tty_struct *);
static int pc_chars_in_buffer(struct tty_struct *);
static void pc_flush_buffer(struct tty_struct *);
static void pc_flush_chars(struct tty_struct *);
static int block_til_ready(struct tty_struct *, struct file *,
                           struct channel *);
static int pc_open(struct tty_struct *, struct file *);
static void post_fep_init(unsigned int crd);
static void epcapoll(unsigned long);
static void doevent(int);
static void fepcmd(struct channel *, int, int, int, int, int);
static unsigned termios2digi_h(struct channel *ch, unsigned);
static unsigned termios2digi_i(struct channel *ch, unsigned);
static unsigned termios2digi_c(struct channel *ch, unsigned);
static void epcaparam(struct tty_struct *, struct channel *);
static void receive_data(struct channel *);
static int pc_ioctl(struct tty_struct *, struct file *,
                    unsigned int, unsigned long);
static void pc_set_termios(struct tty_struct *, struct termios *);
static void do_softint(void *);
static void pc_stop(struct tty_struct *);
static void pc_start(struct tty_struct *);
static void pc_throttle(struct tty_struct * tty);
static void pc_unthrottle(struct tty_struct *tty);
static void digi_send_break(struct channel *ch, int msec);
static void setup_empty_event(struct tty_struct *tty, struct channel *ch);
void epca_setup(char *, int *);
void console_print(const char *);

static int get_termio(struct tty_struct *, struct termio *);
static int pc_write(struct tty_struct *, int, const unsigned char *, int);
int pc_init(void);

#ifdef ENABLE_PCI
static int init_PCI(void);
#endif /* ENABLE_PCI */


/* ------------------------------------------------------------------
        Table of functions for each board to handle memory.  Mantaining 
        parallelism is a *very* good idea here.  The idea is for the 
        runtime code to blindly call these functions, not knowing/caring    
        about the underlying hardware.  This stuff should contain no
        conditionals; if more functionality is needed a different entry
        should be established.  These calls are the interface calls and 
        are the only functions that should be accessed.  Anyone caught
        making direct calls deserves what they get.
-------------------------------------------------------------------- */

static inline void memwinon(struct board_info *b, unsigned int win)
{
        (b->memwinon)(b, win);
}

static inline void memwinoff(struct board_info *b, unsigned int win)
{
        (b->memwinoff)(b, win);
}

static inline void globalwinon(struct channel *ch)
{
        (ch->board->globalwinon)(ch);
}

static inline void rxwinon(struct channel *ch)
{
        (ch->board->rxwinon)(ch);
}

static inline void txwinon(struct channel *ch)
{
        (ch->board->txwinon)(ch);
}

static inline void memoff(struct channel *ch)
{
        (ch->board->memoff)(ch);
}
static inline void assertgwinon(struct channel *ch)
{
        (ch->board->assertgwinon)(ch);
}

static inline void assertmemoff(struct channel *ch)
{
        (ch->board->assertmemoff)(ch);
}

/* ---------------------------------------------------------
        PCXEM windowing is the same as that used in the PCXR 
        and CX series cards.
------------------------------------------------------------ */

static inline void pcxem_memwinon(struct board_info *b, unsigned int win)
{
        outb_p(FEPWIN|win, (int)b->port + 1);
}

static inline void pcxem_memwinoff(struct board_info *b, unsigned int win)
{
        outb_p(0, (int)b->port + 1);
}

static inline void pcxem_globalwinon(struct channel *ch)
{
        outb_p( FEPWIN, (int)ch->board->port + 1);
}

static inline void pcxem_rxwinon(struct channel *ch)
{
        outb_p(ch->rxwin, (int)ch->board->port + 1);
}

static inline void pcxem_txwinon(struct channel *ch)
{
        outb_p(ch->txwin, (int)ch->board->port + 1);
}

static inline void pcxem_memoff(struct channel *ch)
{
        outb_p(0, (int)ch->board->port + 1);
}

/* ----------------- Begin pcxe memory window stuff ------------------ */

static inline void pcxe_memwinon(struct board_info *b, unsigned int win)
{
               outb_p(FEPWIN | win, (int)b->port + 1);
}

static inline void pcxe_memwinoff(struct board_info *b, unsigned int win)
{
        outb_p(inb((int)b->port) & ~FEPMEM,
                   (int)b->port + 1);
        outb_p(0, (int)b->port + 1);
}

static inline void pcxe_globalwinon(struct channel *ch)
{
        outb_p( FEPWIN, (int)ch->board->port + 1);
}

static inline void pcxe_rxwinon(struct channel *ch)
{
                outb_p(ch->rxwin, (int)ch->board->port + 1);
}

static inline void pcxe_txwinon(struct channel *ch)
{
                outb_p(ch->txwin, (int)ch->board->port + 1);
}

static inline void pcxe_memoff(struct channel *ch)
{
        outb_p(0, (int)ch->board->port);
        outb_p(0, (int)ch->board->port + 1);
}

/* ------------- Begin pc64xe and pcxi memory window stuff -------------- */

static inline void pcxi_memwinon(struct board_info *b, unsigned int win)
{
               outb_p(inb((int)b->port) | FEPMEM, (int)b->port);
}

static inline void pcxi_memwinoff(struct board_info *b, unsigned int win)
{
        outb_p(inb((int)b->port) & ~FEPMEM, (int)b->port);
}

static inline void pcxi_globalwinon(struct channel *ch)
{
        outb_p(FEPMEM, (int)ch->board->port);
}

static inline void pcxi_rxwinon(struct channel *ch)
{
                outb_p(FEPMEM, (int)ch->board->port);
}

static inline void pcxi_txwinon(struct channel *ch)
{
                outb_p(FEPMEM, (int)ch->board->port);
}

static inline void pcxi_memoff(struct channel *ch)
{
        outb_p(0, (int)ch->board->port);
}

static inline void pcxi_assertgwinon(struct channel *ch)
{
        epcaassert(inb((int)ch->board->port) & FEPMEM, "Global memory off");
}

static inline void pcxi_assertmemoff(struct channel *ch)
{
        epcaassert(!(inb((int)ch->board->port) & FEPMEM), "Memory on");
}


/* ----------------------------------------------------------------------
        Not all of the cards need specific memory windowing routines.  Some
        cards (Such as PCI) needs no windowing routines at all.  We provide
        these do nothing routines so that the same code base can be used.
        The driver will ALWAYS call a windowing routine if it thinks it needs
        to; regardless of the card.  However, dependent on the card the routine
        may or may not do anything.
---------------------------------------------------------------------------*/

static inline void dummy_memwinon(struct board_info *b, unsigned int win)
{
}

static inline void dummy_memwinoff(struct board_info *b, unsigned int win)
{
}

static inline void dummy_globalwinon(struct channel *ch)
{
}

static inline void dummy_rxwinon(struct channel *ch)
{
}

static inline void dummy_txwinon(struct channel *ch)
{
}

static inline void dummy_memoff(struct channel *ch)
{
}

static inline void dummy_assertgwinon(struct channel *ch)
{
}

static inline void dummy_assertmemoff(struct channel *ch)
{
}

/* ----------------- Begin verifyChannel function ----------------------- */
static inline struct channel *verifyChannel(register struct tty_struct *tty)
{ /* Begin verifyChannel */

        /* --------------------------------------------------------------------
                This routine basically provides a sanity check.  It insures that
                the channel returned is within the proper range of addresses as
                well as properly initialized.  If some bogus info gets passed in
                through tty->driver_data this should catch it.
        --------------------------------------------------------------------- */

        if (tty) 
        { /* Begin if tty */

                register struct channel *ch = (struct channel *)tty->driver_data;

                if ((ch >= &digi_channels[0]) && (ch < &digi_channels[nbdevs])) 
                {
                        if (ch->magic == EPCA_MAGIC)
                                return ch;
                }

        } /* End if tty */

        /* Else return a NULL for invalid */
        return NULL;

} /* End verifyChannel */

/* ------------------ Begin pc_sched_event ------------------------- */

static inline void pc_sched_event(struct channel *ch, int event)
{ /* Begin pc_sched_event */


        /* ----------------------------------------------------------------------
                We call this to schedule interrupt processing on some event.  The 
                kernel sees our request and calls the related routine in OUR driver.
        -------------------------------------------------------------------------*/

        ch->event |= 1 << event;
        MOD_INC_USE_COUNT;
        if (schedule_task(&ch->tqueue) == 0)
                MOD_DEC_USE_COUNT;


} /* End pc_sched_event */

/* ------------------ Begin epca_error ------------------------- */

static void epca_error(int line, char *msg)
{ /* Begin epca_error */

        printk(KERN_ERR "epca_error (Digi): line = %d %s\n",line,msg);
        return;

} /* End epca_error */

/* ------------------ Begin pc_close ------------------------- */
static void pc_close(struct tty_struct * tty, struct file * filp)
{ /* Begin pc_close */

        struct channel *ch;
        unsigned long flags;

        if (tty->driver.subtype == SERIAL_TYPE_INFO) 
        {
                return;
        }


        /* ---------------------------------------------------------
                verifyChannel returns the channel from the tty struct
                if it is valid.  This serves as a sanity check.
        ------------------------------------------------------------- */

        if ((ch = verifyChannel(tty)) != NULL) 
        { /* Begin if ch != NULL */

                save_flags(flags);
                cli();

                if (tty_hung_up_p(filp)) 
                {
                        restore_flags(flags);
                        return;
                }

                /* Check to see if the channel is open more than once */
                if (ch->count-- > 1) 
                { /* Begin channel is open more than once */

                        /* -------------------------------------------------------------
                                Return without doing anything.  Someone might still be using
                                the channel.
                        ---------------------------------------------------------------- */

                        restore_flags(flags);
                        return;
                } /* End channel is open more than once */

                /* Port open only once go ahead with shutdown & reset */

                if (ch->count < 0) 
                {
                        ch->count = 0;
                }

                /* ---------------------------------------------------------------
                        Let the rest of the driver know the channel is being closed.
                        This becomes important if an open is attempted before close 
                        is finished.
                ------------------------------------------------------------------ */

                ch->asyncflags |= ASYNC_CLOSING;
        
                /* -------------------------------------------------------------
                        Save the termios structure, since this port may have
                        separate termios for callout and dialin.
                --------------------------------------------------------------- */

                if (ch->asyncflags & ASYNC_NORMAL_ACTIVE)
                        ch->normal_termios = *tty->termios;

                if (ch->asyncflags & ASYNC_CALLOUT_ACTIVE)
                        ch->callout_termios = *tty->termios;

                tty->closing = 1;

                if (ch->asyncflags & ASYNC_INITIALIZED) 
                {
                        /* Setup an event to indicate when the transmit buffer empties */
                        setup_empty_event(tty, ch);             
                        tty_wait_until_sent(tty, 3000); /* 30 seconds timeout */
                }
        
                if (tty->driver.flush_buffer)
                        tty->driver.flush_buffer(tty);

                if (tty->ldisc.flush_buffer)
                        tty->ldisc.flush_buffer(tty);

                shutdown(ch);
                tty->closing = 0;
                ch->event = 0;
                ch->tty = NULL;

                if (ch->blocked_open) 
                { /* Begin if blocked_open */

                        if (ch->close_delay) 
                        {
                                current->state = TASK_INTERRUPTIBLE;
                                schedule_timeout(ch->close_delay);
                        }

                        wake_up_interruptible(&ch->open_wait);

                } /* End if blocked_open */

                ch->asyncflags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_INITIALIZED | 
                                      ASYNC_CALLOUT_ACTIVE | ASYNC_CLOSING);
                wake_up_interruptible(&ch->close_wait);

                MOD_DEC_USE_COUNT;

                restore_flags(flags);

        } /* End if ch != NULL */

} /* End pc_close */ 

/* ------------------ Begin shutdown  ------------------------- */

static void shutdown(struct channel *ch)
{ /* Begin shutdown */

        unsigned long flags;
        struct tty_struct *tty;
        volatile struct board_chan *bc;

        if (!(ch->asyncflags & ASYNC_INITIALIZED)) 
                return;

        save_flags(flags);
        cli();
        globalwinon(ch);

        bc = ch->brdchan;

        /* ------------------------------------------------------------------
                In order for an event to be generated on the receipt of data the
                idata flag must be set. Since we are shutting down, this is not 
                necessary clear this flag.
        --------------------------------------------------------------------- */ 

        if (bc)
                bc->idata = 0;

        tty = ch->tty;

        /* ----------------------------------------------------------------
           If we're a modem control device and HUPCL is on, drop RTS & DTR.
        ------------------------------------------------------------------ */

        if (tty->termios->c_cflag & HUPCL) 
        {
                ch->omodem &= ~(ch->m_rts | ch->m_dtr);
                fepcmd(ch, SETMODEM, 0, ch->m_dtr | ch->m_rts, 10, 1);
        }

        memoff(ch);

        /* ------------------------------------------------------------------
                The channel has officialy been closed.  The next time it is opened
                it will have to reinitialized.  Set a flag to indicate this.
        ---------------------------------------------------------------------- */

        /* Prevent future Digi programmed interrupts from coming active */

        ch->asyncflags &= ~ASYNC_INITIALIZED;
        restore_flags(flags);

} /* End shutdown */

/* ------------------ Begin pc_hangup  ------------------------- */

static void pc_hangup(struct tty_struct *tty)
{ /* Begin pc_hangup */

        struct channel *ch;
        
        /* ---------------------------------------------------------
                verifyChannel returns the channel from the tty struct
                if it is valid.  This serves as a sanity check.
        ------------------------------------------------------------- */

        if ((ch = verifyChannel(tty)) != NULL) 
        { /* Begin if ch != NULL */

                unsigned long flags;

                save_flags(flags);
                cli();
                if (tty->driver.flush_buffer)
                        tty->driver.flush_buffer(tty);

                if (tty->ldisc.flush_buffer)
                        tty->ldisc.flush_buffer(tty);

                shutdown(ch);

                if (ch->count)
                        MOD_DEC_USE_COUNT;
                

                ch->tty   = NULL;
                ch->event = 0;
                ch->count = 0;
                restore_flags(flags);
                ch->asyncflags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_INITIALIZED | ASYNC_CALLOUT_ACTIVE);
                wake_up_interruptible(&ch->open_wait);

        } /* End if ch != NULL */

} /* End pc_hangup */

/* ------------------ Begin pc_write  ------------------------- */

static int pc_write(struct tty_struct * tty, int from_user,
                    const unsigned char *buf, int bytesAvailable)
{ /* Begin pc_write */

        register unsigned int head, tail;
        register int dataLen;
        register int size;
        register int amountCopied;


        struct channel *ch;
        unsigned long flags;
        int remain;
        volatile struct board_chan *bc;


        /* ----------------------------------------------------------------
                pc_write is primarily called directly by the kernel routine
                tty_write (Though it can also be called by put_char) found in
                tty_io.c.  pc_write is passed a line discipline buffer where 
                the data to be written out is stored.  The line discipline 
                implementation itself is done at the kernel level and is not 
                brought into the driver.  
        ------------------------------------------------------------------- */

        /* Stop users from hurting themselves on control minor */

        if (tty->driver.subtype == SERIAL_TYPE_INFO) 
        {
                return (0) ;
        }

        /* ---------------------------------------------------------
                verifyChannel returns the channel from the tty struct
                if it is valid.  This serves as a sanity check.
        ------------------------------------------------------------- */

        if ((ch = verifyChannel(tty)) == NULL)
                return 0;

        /* Make a pointer to the channel data structure found on the board. */

        bc   = ch->brdchan;
        size = ch->txbufsize;

        if (from_user) 
        { /* Begin from_user */

                save_flags(flags);
                cli();

                globalwinon(ch);

                /* -----------------------------------------------------------------    
                        Anding against size will wrap the pointer back to its beginning 
                        position if it is necessary.  This will only work if size is
                        a power of 2 which should always be the case.  Size is determined 
                        by the cards on board FEP/OS.
                -------------------------------------------------------------------- */ 

                /* head refers to the next empty location in which data may be stored */ 

                head = bc->tin & (size - 1);

                /* tail refers to the next data byte to be transmitted */ 

                tail = bc->tout;

                /* Consider changing this to a do statement to make sure */

                if (tail != bc->tout)
                        tail = bc->tout;

                /* ------------------------------------------------------------------   
                        Anding against size will wrap the pointer back to its beginning 
                        position if it is necessary.  This will only work if size is
                        a power of 2 which should always be the case.  Size is determined 
                        by the cards on board FEP/OS.
                --------------------------------------------------------------------- */        

                tail &= (size - 1);

                /* -----------------------------------------------------------------
                        Two situations can affect how space in the transmit buffer
                        is calculated.  You can have a situation where the transmit
                        in pointer (tin) head has wrapped around and actually has a 
                        lower address than the transmit out pointer (tout) tail; or
                        the transmit in pointer (tin) head will not be wrapped around
                        yet, and have a higher address than the transmit out pointer
                        (tout) tail.  Obviously space available in the transmit buffer
                        is calculated differently for each case.

                        Example 1:
                        
                        Consider a 10 byte buffer where head is a pointer to the next
                        empty location in the buffer and tail is a pointer to the next 
                        byte to transmit.  In this example head will not have wrapped 
                        around and therefore head > tail.  

                        0      1      2      3      4      5      6      7      8      9   
                                tail                               head

                        The above diagram shows that buffer locations 2,3,4,5 and 6 have
                        data to be transmitted, while head points at the next empty
                        location.  To calculate how much space is available first we have
                        to determine if the head pointer (tin) has wrapped.  To do this
                        compare the head pointer to the tail pointer,  If head is equal
                        or greater than tail; then it has not wrapped; and the space may
                        be calculated by subtracting tail from head and then subtracting
                        that value from the buffers size.  A one is subtracted from the
                        new value to indicate how much space is available between the 
                        head pointer and end of buffer; as well as the space between the
                        beginning of the buffer and the tail.  If the head is not greater
                        or equal to the tail this indicates that the head has wrapped
                        around to the beginning of the buffer.  To calculate the space 
                        available in this case simply subtract head from tail.  This new 
                        value minus one represents the space available betwwen the head 
                        and tail pointers.  In this example head (7) is greater than tail (2)
                        and therefore has not wrapped around.  We find the space by first
                        subtracting tail from head (7-2=5).  We then subtract this value
                        from the buffer size of ten and subtract one (10-5-1=4).  The space
                        remaining is 4 bytes. 

                        Example 2:
                        
                        Consider a 10 byte buffer where head is a pointer to the next
                        empty location in the buffer and tail is a pointer to the next 
                        byte to transmit.  In this example head will wrapped around and 
                        therefore head < tail.  

                        0      1      2      3      4      5      6      7      8      9   
                                head                               tail

                        The above diagram shows that buffer locations 7,8,9,0 and 1 have
                        data to be transmitted, while head points at the next empty
                        location.  To find the space available we compare head to tail.  If
                        head is not equal to, or greater than tail this indicates that head
                        has wrapped around. In this case head (2) is not equal to, or
                        greater than tail (7) and therefore has already wrapped around.  To
                        calculate the available space between the two pointers we subtract
                        head from tail (7-2=5).  We then subtract one from this new value
                        (5-1=4).  We have 5 bytes empty remaining in the buffer.  Unlike the
                        previous example these five bytes are located between the head and
                        tail pointers. 

                ----------------------------------------------------------------------- */

                dataLen = (head >= tail) ? (size - (head - tail) - 1) : (tail - head - 1);

                /* ----------------------------------------------------------------------
                        In this case bytesAvailable has been passed into pc_write and
                        represents the amount of data that needs to be written.  dataLen
                        represents the amount of space available on the card.  Whichever
                        value is smaller will be the amount actually written. 
                        bytesAvailable will then take on this newly calculated value.
                ---------------------------------------------------------------------- */

                bytesAvailable = MIN(dataLen, bytesAvailable);

                /* First we read the data in from the file system into a temp buffer */

                memoff(ch);
                restore_flags(flags);

                if (bytesAvailable) 
                { /* Begin bytesAvailable */

                        /* Can the user buffer be accessed at the moment ? */
                        if (verify_area(VERIFY_READ, (char*)buf, bytesAvailable))
                                bytesAvailable = 0; /* Can't do; try again later */
                        else  /* Evidently it can, began transmission */
                        { /* Begin if area verified */
                                /* ---------------------------------------------------------------
                                        The below function reads data from user memory.  This routine
                                        can not be used in an interrupt routine. (Because it may 
                                        generate a page fault)  It can only be called while we can the
                                        user context is accessible. 

                                        The prototype is :
                                        inline void copy_from_user(void * to, const void * from,
                                                                  unsigned long count);

                                        You must include <asm/segment.h>
                                        I also think (Check hackers guide) that optimization must
                                        be turned ON.  (Which sounds strange to me...)
        
                                        Remember copy_from_user WILL generate a page fault if the
                                        user memory being accessed has been swapped out.  This can
                                        cause this routine to temporarily sleep while this page
                                        fault is occuring.
                                
                                ----------------------------------------------------------------- */

                                if (copy_from_user(ch->tmp_buf, buf,
                                                   bytesAvailable))
                                        return -EFAULT;

                        } /* End if area verified */

                } /* End bytesAvailable */

                /* ------------------------------------------------------------------ 
                        Set buf to this address for the moment.  tmp_buf was allocated in
                        post_fep_init.
                --------------------------------------------------------------------- */
                buf = ch->tmp_buf;

        } /* End from_user */

        /* All data is now local */

        amountCopied = 0;
        save_flags(flags);
        cli();

        globalwinon(ch);

        head = bc->tin & (size - 1);
        tail = bc->tout;

        if (tail != bc->tout)
                tail = bc->tout;
        tail &= (size - 1);

        /*      If head >= tail, head has not wrapped around. */ 
        if (head >= tail) 
        { /* Begin head has not wrapped */

                /* ---------------------------------------------------------------
                        remain (much like dataLen above) represents the total amount of
                        space available on the card for data.  Here dataLen represents
                        the space existing between the head pointer and the end of 
                        buffer.  This is important because a memcpy cannot be told to
                        automatically wrap around when it hits the buffer end.
                ------------------------------------------------------------------ */ 

                dataLen = size - head;
                remain = size - (head - tail) - 1;

        } /* End head has not wrapped */
        else 
        { /* Begin head has wrapped around */

                remain = tail - head - 1;
                dataLen = remain;

        } /* End head has wrapped around */

        /* -------------------------------------------------------------------
                        Check the space on the card.  If we have more data than 
                        space; reduce the amount of data to fit the space.
        ---------------------------------------------------------------------- */

        bytesAvailable = MIN(remain, bytesAvailable);

        txwinon(ch);
        while (bytesAvailable > 0) 
        { /* Begin while there is data to copy onto card */

                /* -----------------------------------------------------------------
                        If head is not wrapped, the below will make sure the first 
                        data copy fills to the end of card buffer.
                ------------------------------------------------------------------- */

                dataLen = MIN(bytesAvailable, dataLen);
                memcpy(ch->txptr + head, buf, dataLen);
                buf += dataLen;
                head += dataLen;
                amountCopied += dataLen;
                bytesAvailable -= dataLen;

                if (head >= size) 
                {
                        head = 0;
                        dataLen = tail;
                }

        } /* End while there is data to copy onto card */

        ch->statusflags |= TXBUSY;
        globalwinon(ch);
        bc->tin = head;

        if ((ch->statusflags & LOWWAIT) == 0) 
        {
                ch->statusflags |= LOWWAIT;
                bc->ilow = 1;
        }
        memoff(ch);
        restore_flags(flags);

        return(amountCopied);

} /* End pc_write */

/* ------------------ Begin pc_put_char  ------------------------- */

static void pc_put_char(struct tty_struct *tty, unsigned char c)
{ /* Begin pc_put_char */

   
        pc_write(tty, 0, &c, 1);
        return;

} /* End pc_put_char */

/* ------------------ Begin pc_write_room  ------------------------- */

static int pc_write_room(struct tty_struct *tty)
{ /* Begin pc_write_room */

        int remain;
        struct channel *ch;
        unsigned long flags;
        unsigned int head, tail;
        volatile struct board_chan *bc;

        remain = 0;

        /* ---------------------------------------------------------
                verifyChannel returns the channel from the tty struct
                if it is valid.  This serves as a sanity check.
        ------------------------------------------------------------- */

        if ((ch = verifyChannel(tty)) != NULL) 
        {
                save_flags(flags);
                cli();
                globalwinon(ch);

                bc   = ch->brdchan;
                head = bc->tin & (ch->txbufsize - 1);
                tail = bc->tout;

                if (tail != bc->tout)
                        tail = bc->tout;
                /* Wrap tail if necessary */
                tail &= (ch->txbufsize - 1);

                if ((remain = tail - head - 1) < 0 )
                        remain += ch->txbufsize;

                if (remain && (ch->statusflags & LOWWAIT) == 0) 
                {
                        ch->statusflags |= LOWWAIT;
                        bc->ilow = 1;
                }
                memoff(ch);
                restore_flags(flags);
        }

        /* Return how much room is left on card */
        return remain;

} /* End pc_write_room */

/* ------------------ Begin pc_chars_in_buffer  ---------------------- */

static int pc_chars_in_buffer(struct tty_struct *tty)
{ /* Begin pc_chars_in_buffer */

        int chars;
        unsigned int ctail, head, tail;
        int remain;
        unsigned long flags;
        struct channel *ch;
        volatile struct board_chan *bc;


        /* ---------------------------------------------------------
                verifyChannel returns the channel from the tty struct
                if it is valid.  This serves as a sanity check.
        ------------------------------------------------------------- */

        if ((ch = verifyChannel(tty)) == NULL)
                return(0);

        save_flags(flags);
        cli();
        globalwinon(ch);

        bc = ch->brdchan;
        tail = bc->tout;
        head = bc->tin;
        ctail = ch->mailbox->cout;

        if (tail == head && ch->mailbox->cin == ctail && bc->tbusy == 0)
                chars = 0;
        else 
        { /* Begin if some space on the card has been used */

                head = bc->tin & (ch->txbufsize - 1);
                tail &= (ch->txbufsize - 1);

                /*  --------------------------------------------------------------
                        The logic here is basically opposite of the above pc_write_room
                        here we are finding the amount of bytes in the buffer filled.
                        Not the amount of bytes empty.
                ------------------------------------------------------------------- */

                if ((remain = tail - head - 1) < 0 )
                        remain += ch->txbufsize;

                chars = (int)(ch->txbufsize - remain);

                /* -------------------------------------------------------------  
                        Make it possible to wakeup anything waiting for output
                        in tty_ioctl.c, etc.

                        If not already set.  Setup an event to indicate when the
                        transmit buffer empties 
                ----------------------------------------------------------------- */

                if (!(ch->statusflags & EMPTYWAIT))
                        setup_empty_event(tty,ch);

        } /* End if some space on the card has been used */

        memoff(ch);
        restore_flags(flags);

        /* Return number of characters residing on card. */
        return(chars);

} /* End pc_chars_in_buffer */

/* ------------------ Begin pc_flush_buffer  ---------------------- */

static void pc_flush_buffer(struct tty_struct *tty)
{ /* Begin pc_flush_buffer */

        unsigned int tail;
        unsigned long flags;
        struct channel *ch;
        volatile struct board_chan *bc;


        /* ---------------------------------------------------------
                verifyChannel returns the channel from the tty struct
                if it is valid.  This serves as a sanity check.
        ------------------------------------------------------------- */

        if ((ch = verifyChannel(tty)) == NULL)
                return;

        save_flags(flags);
        cli();

        globalwinon(ch);

        bc   = ch->brdchan;
        tail = bc->tout;

        /* Have FEP move tout pointer; effectively flushing transmit buffer */

        fepcmd(ch, STOUT, (unsigned) tail, 0, 0, 0);

        memoff(ch);
        restore_flags(flags);

        wake_up_interruptible(&tty->write_wait);
        if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) && tty->ldisc.write_wakeup)
                (tty->ldisc.write_wakeup)(tty);

} /* End pc_flush_buffer */

/* ------------------ Begin pc_flush_chars  ---------------------- */

static void pc_flush_chars(struct tty_struct *tty)
{ /* Begin pc_flush_chars */

        struct channel * ch;

        /* ---------------------------------------------------------
                verifyChannel returns the channel from the tty struct
                if it is valid.  This serves as a sanity check.
        ------------------------------------------------------------- */

        if ((ch = verifyChannel(tty)) != NULL) 
        {
                unsigned long flags;

                save_flags(flags);
                cli();

                /* ----------------------------------------------------------------
                        If not already set and the transmitter is busy setup an event
                        to indicate when the transmit empties.
                ------------------------------------------------------------------- */

                if ((ch->statusflags & TXBUSY) && !(ch->statusflags & EMPTYWAIT))
                        setup_empty_event(tty,ch);

                restore_flags(flags);
        }

} /* End pc_flush_chars */

/* ------------------ Begin block_til_ready  ---------------------- */

static int block_til_ready(struct tty_struct *tty, 
                           struct file *filp, struct channel *ch)
{ /* Begin block_til_ready */

        DECLARE_WAITQUEUE(wait,current);
        int     retval, do_clocal = 0;
        unsigned long flags;


        if (tty_hung_up_p(filp))
        {
                if (ch->asyncflags & ASYNC_HUP_NOTIFY)
                        retval = -EAGAIN;
                else
                        retval = -ERESTARTSYS;  
                return(retval);
        }

        /* ----------------------------------------------------------------- 
                If the device is in the middle of being closed, then block
                until it's done, and then try again.
        -------------------------------------------------------------------- */
        if (ch->asyncflags & ASYNC_CLOSING) 
        {
                interruptible_sleep_on(&ch->close_wait);

                if (ch->asyncflags & ASYNC_HUP_NOTIFY)
                        return -EAGAIN;
                else
                        return -ERESTARTSYS;
        }

        /* ----------------------------------------------------------------- 
           If this is a callout device, then just make sure the normal
           device isn't being used.
        -------------------------------------------------------------------- */

        if (tty->driver.subtype == SERIAL_TYPE_CALLOUT) 
        { /* A cud device has been opened */
                if (ch->asyncflags & ASYNC_NORMAL_ACTIVE)
                        return -EBUSY;

                if ((ch->asyncflags & ASYNC_CALLOUT_ACTIVE) &&
                    (ch->asyncflags & ASYNC_SESSION_LOCKOUT) &&
                    (ch->session != current->session))
                    return -EBUSY;

                if ((ch->asyncflags & ASYNC_CALLOUT_ACTIVE) &&
                    (ch->asyncflags & ASYNC_PGRP_LOCKOUT) &&
                    (ch->pgrp != current->pgrp))
                    return -EBUSY;
 
                ch->asyncflags |= ASYNC_CALLOUT_ACTIVE;

                return 0;
        } /* End a cud device has been opened */

        if (filp->f_flags & O_NONBLOCK) 
        {
                /* ----------------------------------------------------------------- 
                 If non-blocking mode is set, then make the check up front
                 and then exit.
                -------------------------------------------------------------------- */

                if (ch->asyncflags & ASYNC_CALLOUT_ACTIVE)
                        return -EBUSY;

                ch->asyncflags |= ASYNC_NORMAL_ACTIVE;

                return 0;
        }


        if (ch->asyncflags & ASYNC_CALLOUT_ACTIVE) 
        {
                if (ch->normal_termios.c_cflag & CLOCAL)
                        do_clocal = 1;
        }
        else 
        {
                if (tty->termios->c_cflag & CLOCAL)
                        do_clocal = 1;
        }
        
   /* Block waiting for the carrier detect and the line to become free */
        
        retval = 0;
        add_wait_queue(&ch->open_wait, &wait);
        save_flags(flags);
        cli();


        /* We dec count so that pc_close will know when to free things */
        if (!tty_hung_up_p(filp))
                ch->count--;

        restore_flags(flags);

        ch->blocked_open++;

        while(1) 
        { /* Begin forever while  */

                set_current_state(TASK_INTERRUPTIBLE);

                if (tty_hung_up_p(filp) ||
                    !(ch->asyncflags & ASYNC_INITIALIZED)) 
                {
                        if (ch->asyncflags & ASYNC_HUP_NOTIFY)
                                retval = -EAGAIN;
                        else
                                retval = -ERESTARTSYS;  
                        break;
                }

                if (!(ch->asyncflags & ASYNC_CLOSING) && 
                    !(ch->asyncflags & ASYNC_CALLOUT_ACTIVE) &&
                          (do_clocal || (ch->imodem & ch->dcd)))
                        break;

                if (signal_pending(current)) 
                {
                        retval = -ERESTARTSYS;
                        break;
                }

                /* ---------------------------------------------------------------
                        Allow someone else to be scheduled.  We will occasionally go
                        through this loop until one of the above conditions change.
                        The below schedule call will allow other processes to enter and
                        prevent this loop from hogging the cpu.
                ------------------------------------------------------------------ */
                schedule();

        } /* End forever while  */

        current->state = TASK_RUNNING;
        remove_wait_queue(&ch->open_wait, &wait);
        cli();
        if (!tty_hung_up_p(filp))
                ch->count++;
        restore_flags(flags);

        ch->blocked_open--;

        if (retval)
                return retval;

        ch->asyncflags |= ASYNC_NORMAL_ACTIVE;

        return 0;

} /* End block_til_ready */     

/* ------------------ Begin pc_open  ---------------------- */

static int pc_open(struct tty_struct *tty, struct file * filp)
{ /* Begin pc_open */

        struct channel *ch;
        unsigned long flags;
        int line, retval, boardnum;
        volatile struct board_chan *bc;
        volatile unsigned int head;

        /* Nothing "real" happens in open of control device */

        if (tty->driver.subtype == SERIAL_TYPE_INFO) 
        {
                return (0) ;
        }

        line = MINOR(tty->device) - tty->driver.minor_start;
        if (line < 0 || line >= nbdevs) 
        {
                printk(KERN_ERR "<Error> - pc_open : line out of range in pc_open\n");
                tty->driver_data = NULL;
                return(-ENODEV);
        }


        MOD_INC_USE_COUNT;

        ch = &digi_channels[line];
        boardnum = ch->boardnum;

        /* Check status of board configured in system.  */

        /* -----------------------------------------------------------------
                I check to see if the epca_setup routine detected an user error.  
                It might be better to put this in pc_init, but for the moment it
                goes here.
        ---------------------------------------------------------------------- */

        if (invalid_lilo_config)
        {
                if (setup_error_code & INVALID_BOARD_TYPE)
                        printk(KERN_ERR "<Error> - pc_open: Invalid board type specified in LILO command\n");

                if (setup_error_code & INVALID_NUM_PORTS)
                        printk(KERN_ERR "<Error> - pc_open: Invalid number of ports specified in LILO command\n");

                if (setup_error_code & INVALID_MEM_BASE)
                        printk(KERN_ERR "<Error> - pc_open: Invalid board memory address specified in LILO command\n");

                if (setup_error_code & INVALID_PORT_BASE)
                        printk(KERN_ERR "<Error> - pc_open: Invalid board port address specified in LILO command\n");

                if (setup_error_code & INVALID_BOARD_STATUS)
                        printk(KERN_ERR "<Error> - pc_open: Invalid board status specified in LILO command\n");

                if (setup_error_code & INVALID_ALTPIN)
                        printk(KERN_ERR "<Error> - pc_open: Invalid board altpin specified in LILO command\n");

                tty->driver_data = NULL;   /* Mark this device as 'down' */
                return(-ENODEV);
        }

        if ((boardnum >= num_cards) || (boards[boardnum].status == DISABLED)) 
        {
                tty->driver_data = NULL;   /* Mark this device as 'down' */
                return(-ENODEV);
        }
        
        if (( bc = ch->brdchan) == 0) 
        {
                tty->driver_data = NULL;
                return(-ENODEV);
        }

        /* ------------------------------------------------------------------
                Every time a channel is opened, increment a counter.  This is 
                necessary because we do not wish to flush and shutdown the channel
                until the last app holding the channel open, closes it.         
        --------------------------------------------------------------------- */

        ch->count++;

        /* ----------------------------------------------------------------
                Set a kernel structures pointer to our local channel 
                structure.  This way we can get to it when passed only
                a tty struct.
        ------------------------------------------------------------------ */

        tty->driver_data = ch;
        
        /* ----------------------------------------------------------------
                If this is the first time the channel has been opened, initialize
                the tty->termios struct otherwise let pc_close handle it.
        -------------------------------------------------------------------- */

        /* Should this be here except for SPLIT termios ? */
        if (ch->count == 1) 
        {
                if (tty->driver.subtype == SERIAL_TYPE_NORMAL)
                        *tty->termios = ch->normal_termios;
                else 
                        *tty->termios = ch->callout_termios;
        }

        ch->session = current->session;
        ch->pgrp = current->pgrp;

        save_flags(flags);
        cli();

        globalwinon(ch);
        ch->statusflags = 0;

        /* Save boards current modem status */
        ch->imodem = bc->mstat;

        /* ----------------------------------------------------------------
           Set receive head and tail ptrs to each other.  This indicates
           no data available to read.
        ----------------------------------------------------------------- */
        head = bc->rin;
        bc->rout = head;

        /* Set the channels associated tty structure */
        ch->tty = tty;

        /* -----------------------------------------------------------------
                The below routine generally sets up parity, baud, flow control 
                issues, etc.... It effect both control flags and input flags.
        -------------------------------------------------------------------- */
        epcaparam(tty,ch);

        ch->asyncflags |= ASYNC_INITIALIZED;
        memoff(ch);

        restore_flags(flags);

        retval = block_til_ready(tty, filp, ch);
        if (retval)
        {
                return retval;
        }

        /* -------------------------------------------------------------
                Set this again in case a hangup set it to zero while this 
                open() was waiting for the line...
        --------------------------------------------------------------- */
        ch->tty = tty;

        save_flags(flags);
        cli();
        globalwinon(ch);

        /* Enable Digi Data events */
        bc->idata = 1;

        memoff(ch);
        restore_flags(flags);

        return 0;

} /* End pc_open */

#ifdef MODULE
/* -------------------- Begin init_module ---------------------- */
int __init init_module()
{ /* Begin init_module */

        unsigned long   flags;

        save_flags(flags);
        cli();

        pc_init();

        restore_flags(flags);

        return(0);
} /* End init_module */

#endif

#ifdef ENABLE_PCI
static struct pci_driver epca_driver;
#endif

#ifdef MODULE
/* -------------------- Begin cleanup_module  ---------------------- */

void cleanup_module()
{ /* Begin cleanup_module */

        int               count, crd;
        struct board_info *bd;
        struct channel    *ch;
        unsigned long     flags;

        del_timer_sync(&epca_timer);

        save_flags(flags);
        cli();

        if ((tty_unregister_driver(&pc_driver)) ||  
            (tty_unregister_driver(&pc_callout)) ||
            (tty_unregister_driver(&pc_info)))
        {
                printk(KERN_WARNING "<Error> - DIGI : cleanup_module failed to un-register tty driver\n");
                restore_flags(flags);
                return;
        }

        for (crd = 0; crd < num_cards; crd++) 
        { /* Begin for each card */

                bd = &boards[crd];

                if (!bd)
                { /* Begin sanity check */
                        printk(KERN_ERR "<Error> - Digi : cleanup_module failed\n");
                        return;
                } /* End sanity check */

                ch = card_ptr[crd]; 

                for (count = 0; count < bd->numports; count++, ch++) 
                { /* Begin for each port */

                        if (ch) 
                        {
                                if (ch->tty)
                                        tty_hangup(ch->tty);
                                kfree(ch->tmp_buf);
                        }

                } /* End for each port */
        } /* End for each card */

#ifdef ENABLE_PCI
        pci_unregister_driver (&epca_driver);
#endif

        restore_flags(flags);

} /* End cleanup_module */
#endif /* MODULE */

/* ------------------ Begin pc_init  ---------------------- */

int __init pc_init(void)
{ /* Begin pc_init */

        /* ----------------------------------------------------------------
                pc_init is called by the operating system during boot up prior to
                any open calls being made.  In the older versions of Linux (Prior
                to 2.0.0) an entry is made into tty_io.c.  A pointer to the last
                memory location (from kernel space) used (kmem_start) is passed
                to pc_init.  It is pc_inits responsibility to modify this value 
                for any memory that the Digi driver might need and then return
                this value to the operating system.  For example if the driver
                wishes to allocate 1K of kernel memory, pc_init would return 
                (kmem_start + 1024).  This memory (Between kmem_start and kmem_start
                + 1024) would then be available for use exclusively by the driver.  
                In this case our driver does not allocate any of this kernel 
                memory.
        ------------------------------------------------------------------*/

        ulong flags;
        int crd;
        struct board_info *bd;
        unsigned char board_id = 0;
        

#ifdef ENABLE_PCI
        int pci_boards_found, pci_count;

        pci_count = 0;
#endif /* ENABLE_PCI */

        /* -----------------------------------------------------------------------
                If epca_setup has not been ran by LILO set num_cards to defaults; copy
                board structure defined by digiConfig into drivers board structure.
                Note : If LILO has ran epca_setup then epca_setup will handle defining
                num_cards as well as copying the data into the board structure.
        -------------------------------------------------------------------------- */
        if (!liloconfig)
        { /* Begin driver has been configured via. epcaconfig */

                nbdevs = NBDEVS;
                num_cards = NUMCARDS;
                memcpy((void *)&boards, (void *)&static_boards,
                       (sizeof(struct board_info) * NUMCARDS));
        } /* End driver has been configured via. epcaconfig */

        /* -----------------------------------------------------------------
                Note : If lilo was used to configure the driver and the 
                ignore epcaconfig option was choosen (digiepca=2) then 
                nbdevs and num_cards will equal 0 at this point.  This is
                okay; PCI cards will still be picked up if detected.
        --------------------------------------------------------------------- */

        /*  -----------------------------------------------------------
                Set up interrupt, we will worry about memory allocation in
                post_fep_init. 
        --------------------------------------------------------------- */


        printk(KERN_INFO "DIGI epca driver version %s loaded.\n",VERSION);

#ifdef ENABLE_PCI

        /* ------------------------------------------------------------------
                NOTE : This code assumes that the number of ports found in 
                       the boards array is correct.  This could be wrong if
                       the card in question is PCI (And therefore has no ports 
                       entry in the boards structure.)  The rest of the 
                       information will be valid for PCI because the beginning
                       of pc_init scans for PCI and determines i/o and base
                       memory addresses.  I am not sure if it is possible to 
                       read the number of ports supported by the card prior to
                       it being booted (Since that is the state it is in when 
                       pc_init is run).  Because it is not possible to query the
                       number of supported ports until after the card has booted;
                       we are required to calculate the card_ptrs as the card is         
                       is initialized (Inside post_fep_init).  The negative thing
                       about this approach is that digiDload's call to GET_INFO
                       will have a bad port value.  (Since this is called prior
                       to post_fep_init.)

        --------------------------------------------------------------------- */
  
        pci_boards_found = 0;
        if (pci_present())
        {
                if(num_cards < MAXBOARDS)
                        pci_boards_found += init_PCI();
                num_cards += pci_boards_found;
        }
        else 
        {
                printk(KERN_ERR "<Error> - No PCI BIOS found\n");
        }

#endif /* ENABLE_PCI */

        memset(&pc_driver, 0, sizeof(struct tty_driver));
        memset(&pc_callout, 0, sizeof(struct tty_driver));
        memset(&pc_info, 0, sizeof(struct tty_driver));

        pc_driver.magic = TTY_DRIVER_MAGIC;
        pc_driver.name = "ttyD"; 
        pc_driver.major = DIGI_MAJOR; 
        pc_driver.minor_start = 0;
        pc_driver.num = MAX_ALLOC;
        pc_driver.type = TTY_DRIVER_TYPE_SERIAL;
        pc_driver.subtype = SERIAL_TYPE_NORMAL;
        pc_driver.init_termios = tty_std_termios;
        pc_driver.init_termios.c_iflag = 0;
        pc_driver.init_termios.c_oflag = 0;

        pc_driver.init_termios.c_cflag = B9600 | CS8 | CREAD | CLOCAL | HUPCL;
        pc_driver.init_termios.c_lflag = 0;
        pc_driver.flags = TTY_DRIVER_REAL_RAW;
        pc_driver.refcount = &pc_refcount;
        pc_driver.table = pc_table;
        
        /* pc_termios is an array of pointers pointing at termios structs */
        /* The below should get the first pointer */
        pc_driver.termios = pc_termios;
        pc_driver.termios_locked = pc_termios_locked;

        /* ------------------------------------------------------------------
                Setup entry points for the driver.  These are primarily called by 
                the kernel in tty_io.c and n_tty.c
        --------------------------------------------------------------------- */

        pc_driver.open = pc_open;
        pc_driver.close = pc_close;
        pc_driver.write = pc_write;
        pc_driver.write_room = pc_write_room;
        pc_driver.flush_buffer = pc_flush_buffer;
        pc_driver.chars_in_buffer = pc_chars_in_buffer;
        pc_driver.flush_chars = pc_flush_chars;
        pc_driver.put_char = pc_put_char;
        pc_driver.ioctl = pc_ioctl;
        pc_driver.set_termios = pc_set_termios;
        pc_driver.stop = pc_stop;
        pc_driver.start = pc_start;
        pc_driver.throttle = pc_throttle;
        pc_driver.unthrottle = pc_unthrottle;
        pc_driver.hangup = pc_hangup;
        pc_callout = pc_driver;

        pc_callout.name = "cud";
        pc_callout.major = DIGICU_MAJOR;
        pc_callout.minor_start = 0;
        pc_callout.init_termios.c_cflag = B9600 | CS8 | CREAD | CLOCAL | HUPCL;
        pc_callout.subtype = SERIAL_TYPE_CALLOUT;

        pc_info = pc_driver;
        pc_info.name = "digi_ctl";
        pc_info.major = DIGIINFOMAJOR;
        pc_info.minor_start = 0;
        pc_info.num = 1;
        pc_info.init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL;
        pc_info.subtype = SERIAL_TYPE_INFO;


        save_flags(flags);
        cli();

        for (crd = 0; crd < num_cards; crd++) 
        { /* Begin for each card */

                /*  ------------------------------------------------------------------
                        This is where the appropriate memory handlers for the hardware is
                        set.  Everything at runtime blindly jumps through these vectors.
                ---------------------------------------------------------------------- */

                /* defined in epcaconfig.h */
                bd = &boards[crd];

                switch (bd->type)
                { /* Begin switch on bd->type {board type} */
                        case PCXEM:
                        case EISAXEM:
                                bd->memwinon     = pcxem_memwinon ;
                                bd->memwinoff    = pcxem_memwinoff ;
                                bd->globalwinon  = pcxem_globalwinon ;
                                bd->txwinon      = pcxem_txwinon ;
                                bd->rxwinon      = pcxem_rxwinon ;
                                bd->memoff       = pcxem_memoff ;
                                bd->assertgwinon = dummy_assertgwinon;
                                bd->assertmemoff = dummy_assertmemoff;
                                break;

                        case PCIXEM:
                        case PCIXRJ:
                        case PCIXR:
                                bd->memwinon     = dummy_memwinon;
                                bd->memwinoff    = dummy_memwinoff;
                                bd->globalwinon  = dummy_globalwinon;
                                bd->txwinon      = dummy_txwinon;
                                bd->rxwinon      = dummy_rxwinon;
                                bd->memoff       = dummy_memoff;
                                bd->assertgwinon = dummy_assertgwinon;
                                bd->assertmemoff = dummy_assertmemoff;
                                break;

                        case PCXE:
                        case PCXEVE:

                                bd->memwinon     = pcxe_memwinon;
                                bd->memwinoff    = pcxe_memwinoff;
                                bd->globalwinon  = pcxe_globalwinon;
                                bd->txwinon      = pcxe_txwinon;
                                bd->rxwinon      = pcxe_rxwinon;
                                bd->memoff       = pcxe_memoff;
                                bd->assertgwinon = dummy_assertgwinon;
                                bd->assertmemoff = dummy_assertmemoff;
                                break;

                        case PCXI:
                        case PC64XE:

                                bd->memwinon     = pcxi_memwinon;
                                bd->memwinoff    = pcxi_memwinoff;
                                bd->globalwinon  = pcxi_globalwinon;
                                bd->txwinon      = pcxi_txwinon;
                                bd->rxwinon      = pcxi_rxwinon;
                                bd->memoff       = pcxi_memoff;
                                bd->assertgwinon = pcxi_assertgwinon;
                                bd->assertmemoff = pcxi_assertmemoff;
                                break;

                        default:
                                break;

                } /* End switch on bd->type */

                /* ---------------------------------------------------------------
                        Some cards need a memory segment to be defined for use in 
                        transmit and receive windowing operations.  These boards
                        are listed in the below switch.  In the case of the XI the
                        amount of memory on the board is variable so the memory_seg
                        is also variable.  This code determines what they segment 
                        should be.
                ----------------------------------------------------------------- */

                switch (bd->type)
                { /* Begin switch on bd->type {board type} */

                        case PCXE:
                        case PCXEVE:
                        case PC64XE:
                                bd->memory_seg = 0xf000;
                        break;

                        case PCXI:
                                board_id = inb((int)bd->port);
                                if ((board_id & 0x1) == 0x1) 
                                { /* Begin its an XI card */ 

                                        /* Is it a 64K board */
                                        if ((board_id & 0x30) == 0) 
                                                bd->memory_seg = 0xf000;

                                        /* Is it a 128K board */
                                        if ((board_id & 0x30) == 0x10) 
                                                bd->memory_seg = 0xe000;

                                        /* Is is a 256K board */        
                                        if ((board_id & 0x30) == 0x20) 
                                                bd->memory_seg = 0xc000;

                                        /* Is it a 512K board */
                                        if ((board_id & 0x30) == 0x30) 
                                                bd->memory_seg = 0x8000;

                                } /* End it is an XI card */
                                else
                                {
                                        printk(KERN_ERR "<Error> - Board at 0x%x doesn't appear to be an XI\n",(int)bd->port);
                                }
                        break;

                } /* End switch on bd->type */

        } /* End for each card */

        if (tty_register_driver(&pc_driver))
                panic("Couldn't register Digi PC/ driver");

        if (tty_register_driver(&pc_callout))
                panic("Couldn't register Digi PC/ callout");

        if (tty_register_driver(&pc_info))
                panic("Couldn't register Digi PC/ info ");

        /* -------------------------------------------------------------------
           Start up the poller to check for events on all enabled boards
        ---------------------------------------------------------------------- */

        init_timer(&epca_timer);
        epca_timer.function = epcapoll;
        mod_timer(&epca_timer, jiffies + HZ/25);

        restore_flags(flags);

        return 0;

} /* End pc_init */

/* ------------------ Begin post_fep_init  ---------------------- */

static void post_fep_init(unsigned int crd)
{ /* Begin post_fep_init */

        int i;
        unchar *memaddr;
        volatile struct global_data *gd;
        struct board_info *bd;
        volatile struct board_chan *bc;
        struct channel *ch; 
        int shrinkmem = 0, lowwater ; 
 
        /*  -------------------------------------------------------------
                This call is made by the user via. the ioctl call DIGI_INIT.
                It is responsible for setting up all the card specific stuff.
        ---------------------------------------------------------------- */
        bd = &boards[crd];

        /* -----------------------------------------------------------------
                If this is a PCI board, get the port info.  Remember PCI cards
                do not have entries into the epcaconfig.h file, so we can't get 
                the number of ports from it.  Unfortunetly, this means that anyone
                doing a DIGI_GETINFO before the board has booted will get an invalid
                number of ports returned (It should return 0).  Calls to DIGI_GETINFO
                after DIGI_INIT has been called will return the proper values. 
        ------------------------------------------------------------------- */

        if (bd->type >= PCIXEM) /* If the board in question is PCI */
        { /* Begin get PCI number of ports */

                /* --------------------------------------------------------------------
                        Below we use XEMPORTS as a memory offset regardless of which PCI
                        card it is.  This is because all of the supported PCI cards have
                        the same memory offset for the channel data.  This will have to be
                        changed if we ever develop a PCI/XE card.  NOTE : The FEP manual
                        states that the port offset is 0xC22 as opposed to 0xC02.  This is
                        only true for PC/XE, and PC/XI cards; not for the XEM, or CX series.
                        On the PCI cards the number of ports is determined by reading a 
                        ID PROM located in the box attached to the card.  The card can then
                        determine the index the id to determine the number of ports available.
                        (FYI - The id should be located at 0x1ac (And may use up to 4 bytes
                        if the box in question is a XEM or CX)).  
                ------------------------------------------------------------------------ */ 

                bd->numports = (unsigned short)*(unsigned char *)bus_to_virt((unsigned long)
                                                       (bd->re_map_membase + XEMPORTS));

                
                epcaassert(bd->numports <= 64,"PCI returned a invalid number of ports");
                nbdevs += (bd->numports);

        } /* End get PCI number of ports */

        if (crd != 0)
                card_ptr[crd] = card_ptr[crd-1] + boards[crd-1].numports;
        else
                card_ptr[crd] = &digi_channels[crd]; /* <- For card 0 only */

        ch = card_ptr[crd];


        epcaassert(ch <= &digi_channels[nbdevs - 1], "ch out of range");

        memaddr = (unchar *)bd->re_map_membase;

        /* 
           The below command is necessary because newer kernels (2.1.x and
           up) do not have a 1:1 virtual to physical mapping.  The below
           call adjust for that.
        */

        memaddr = (unsigned char *)bus_to_virt((unsigned long)memaddr);

        /* -----------------------------------------------------------------

                The below assignment will set bc to point at the BEGINING of
                the cards channel structures.  For 1 card there will be between
                8 and 64 of these structures.
        -------------------------------------------------------------------- */

        bc = (volatile struct board_chan *)((ulong)memaddr + CHANSTRUCT);

        /* -------------------------------------------------------------------
                The below assignment will set gd to point at the BEGINING of
                global memory address 0xc00.  The first data in that global
                memory actually starts at address 0xc1a.  The command in 
                pointer begins at 0xd10.
        ---------------------------------------------------------------------- */

        gd = (volatile struct global_data *)((ulong)memaddr + GLOBAL);

        /* --------------------------------------------------------------------
                XEPORTS (address 0xc22) points at the number of channels the
                card supports. (For 64XE, XI, XEM, and XR use 0xc02)
        ----------------------------------------------------------------------- */

        if (((bd->type == PCXEVE) | (bd->type == PCXE)) &&
            (*(ushort *)((ulong)memaddr + XEPORTS) < 3))
                shrinkmem = 1;
        if (bd->type < PCIXEM)
                if (!request_region((int)bd->port, 4, board_desc[bd->type]))
                        return;         

        memwinon(bd, 0);

        /*  --------------------------------------------------------------------
                Remember ch is the main drivers channels structure, while bc is 
           the cards channel structure.
        ------------------------------------------------------------------------ */

        /* For every port on the card do ..... */

        for (i = 0; i < bd->numports; i++, ch++, bc++) 
        { /* Begin for each port */

                ch->brdchan        = bc;
                ch->mailbox        = gd; 
                ch->tqueue.routine = do_softint;
                ch->tqueue.data    = ch;
                ch->board          = &boards[crd];

                switch (bd->type)
                { /* Begin switch bd->type */

                        /* ----------------------------------------------------------------
                                Since some of the boards use different bitmaps for their
                                control signals we cannot hard code these values and retain
                                portability.  We virtualize this data here.
                        ------------------------------------------------------------------- */
                        case EISAXEM:
                        case PCXEM:
                        case PCIXEM:
                        case PCIXRJ:
                        case PCIXR:
                                ch->m_rts = 0x02 ;
                                ch->m_dcd = 0x80 ; 
                                ch->m_dsr = 0x20 ;
                                ch->m_cts = 0x10 ;
                                ch->m_ri  = 0x40 ;
                                ch->m_dtr = 0x01 ;
                                break;

                        case PCXE:
                        case PCXEVE:
                        case PCXI:
                        case PC64XE:
                                ch->m_rts = 0x02 ;
                                ch->m_dcd = 0x08 ; 
                                ch->m_dsr = 0x10 ;
                                ch->m_cts = 0x20 ;
                                ch->m_ri  = 0x40 ;
                                ch->m_dtr = 0x80 ;
                                break;
        
                } /* End switch bd->type */

                if (boards[crd].altpin) 
                {
                        ch->dsr = ch->m_dcd;
                        ch->dcd = ch->m_dsr;
                        ch->digiext.digi_flags |= DIGI_ALTPIN;
                }
                else 
                { 
                        ch->dcd = ch->m_dcd;
                        ch->dsr = ch->m_dsr;
                }
        
                ch->boardnum   = crd;
                ch->channelnum = i;
                ch->magic      = EPCA_MAGIC;
                ch->tty        = 0;

                if (shrinkmem) 
                {
                        fepcmd(ch, SETBUFFER, 32, 0, 0, 0);
                        shrinkmem = 0;
                }

                switch (bd->type)
                { /* Begin switch bd->type */

                        case PCIXEM:
                        case PCIXRJ:
                        case PCIXR:
                                /* Cover all the 2MEG cards */
                                ch->txptr = memaddr + (((bc->tseg) << 4) & 0x1fffff);
                                ch->rxptr = memaddr + (((bc->rseg) << 4) & 0x1fffff);
                                ch->txwin = FEPWIN | ((bc->tseg) >> 11);
                                ch->rxwin = FEPWIN | ((bc->rseg) >> 11);
                                break;

                        case PCXEM:
                        case EISAXEM:
                                /* Cover all the 32K windowed cards */
                                /* Mask equal to window size - 1 */
                                ch->txptr = memaddr + (((bc->tseg) << 4) & 0x7fff);
                                ch->rxptr = memaddr + (((bc->rseg) << 4) & 0x7fff);
                                ch->txwin = FEPWIN | ((bc->tseg) >> 11);
                                ch->rxwin = FEPWIN | ((bc->rseg) >> 11);
                                break;

                        case PCXEVE:
                        case PCXE:
                                ch->txptr = memaddr + (((bc->tseg - bd->memory_seg) << 4) & 0x1fff);
                                ch->txwin = FEPWIN | ((bc->tseg - bd->memory_seg) >> 9);
                                ch->rxptr = memaddr + (((bc->rseg - bd->memory_seg) << 4) & 0x1fff);
                                ch->rxwin = FEPWIN | ((bc->rseg - bd->memory_seg) >>9 );
                                break;

                        case PCXI:
                        case PC64XE:
                                ch->txptr = memaddr + ((bc->tseg - bd->memory_seg) << 4);
                                ch->rxptr = memaddr + ((bc->rseg - bd->memory_seg) << 4);
                                ch->txwin = ch->rxwin = 0;
                                break;

                } /* End switch bd->type */

                ch->txbufhead = 0;
                ch->txbufsize = bc->tmax + 1;
        
                ch->rxbufhead = 0;
                ch->rxbufsize = bc->rmax + 1;
        
                lowwater = ch->txbufsize >= 2000 ? 1024 : (ch->txbufsize / 2);

                /* Set transmitter low water mark */
                fepcmd(ch, STXLWATER, lowwater, 0, 10, 0);

                /* Set receiver low water mark */

                fepcmd(ch, SRXLWATER, (ch->rxbufsize / 4), 0, 10, 0);

                /* Set receiver high water mark */

                fepcmd(ch, SRXHWATER, (3 * ch->rxbufsize / 4), 0, 10, 0);

                bc->edelay = 100;
                bc->idata = 1;
        
                ch->startc  = bc->startc;
                ch->stopc   = bc->stopc;
                ch->startca = bc->startca;
                ch->stopca  = bc->stopca;
        
                ch->fepcflag = 0;
                ch->fepiflag = 0;
                ch->fepoflag = 0;
                ch->fepstartc = 0;
                ch->fepstopc = 0;
                ch->fepstartca = 0;
                ch->fepstopca = 0;
        
                ch->close_delay = 50;
                ch->count = 0;
                ch->blocked_open = 0;
                ch->callout_termios = pc_callout.init_termios;
                ch->normal_termios = pc_driver.init_termios;
                init_waitqueue_head(&ch->open_wait);
                init_waitqueue_head(&ch->close_wait);
                ch->tmp_buf = kmalloc(ch->txbufsize,GFP_KERNEL);
                if (!(ch->tmp_buf))
                {
                        printk(KERN_ERR "POST FEP INIT : kmalloc failed for port 0x%x\n",i);
                        release_region((int)bd->port, 4);
                        while(i-- > 0)
                                kfree((ch--)->tmp_buf);
                        return;
                }
                else 
                        memset((void *)ch->tmp_buf,0,ch->txbufsize);
        } /* End for each port */

        printk(KERN_INFO 
                "Digi PC/Xx Driver V%s:  %s I/O = 0x%lx Mem = 0x%lx Ports = %d\n", 
                VERSION, board_desc[bd->type], (long)bd->port, (long)bd->membase, bd->numports);
        sprintf(mesg, 
                "Digi PC/Xx Driver V%s:  %s I/O = 0x%lx Mem = 0x%lx Ports = %d\n", 
                VERSION, board_desc[bd->type], (long)bd->port, (long)bd->membase, bd->numports);
        console_print(mesg);

        memwinoff(bd, 0);

} /* End post_fep_init */

/* --------------------- Begin epcapoll  ------------------------ */

static void epcapoll(unsigned long ignored)
{ /* Begin epcapoll */

        unsigned long flags;
        int crd;
        volatile unsigned int head, tail;
        struct channel *ch;
        struct board_info *bd;

        /* -------------------------------------------------------------------
                This routine is called upon every timer interrupt.  Even though
                the Digi series cards are capable of generating interrupts this 
                method of non-looping polling is more efficient.  This routine
                checks for card generated events (Such as receive data, are transmit
                buffer empty) and acts on those events.
        ----------------------------------------------------------------------- */
        
        save_flags(flags);
        cli();

        for (crd = 0; crd < num_cards; crd++) 
        { /* Begin for each card */

                bd = &boards[crd];
                ch = card_ptr[crd];

                if ((bd->status == DISABLED) || digi_poller_inhibited)
                        continue; /* Begin loop next interation */

                /* -----------------------------------------------------------
                        assertmemoff is not needed here; indeed it is an empty subroutine.
                        It is being kept because future boards may need this as well as
                        some legacy boards.
                ---------------------------------------------------------------- */

                assertmemoff(ch);

                globalwinon(ch);

                /* ---------------------------------------------------------------
                        In this case head and tail actually refer to the event queue not
                        the transmit or receive queue.
                ------------------------------------------------------------------- */

                head = ch->mailbox->ein;
                tail = ch->mailbox->eout;
                
                /* If head isn't equal to tail we have an event */

                if (head != tail)
                        doevent(crd);

                memoff(ch);

        } /* End for each card */

        mod_timer(&epca_timer, jiffies + (HZ / 25));

        restore_flags(flags);
} /* End epcapoll */

/* --------------------- Begin doevent  ------------------------ */

static void doevent(int crd)
{ /* Begin doevent */

        volatile unchar *eventbuf;
        struct channel *ch, *chan0;
        static struct tty_struct *tty;
        volatile struct board_info *bd;
        volatile struct board_chan *bc;
        register volatile unsigned int tail, head;
        register int event, channel;
        register int mstat, lstat;

        /* -------------------------------------------------------------------
                This subroutine is called by epcapoll when an event is detected 
                in the event queue.  This routine responds to those events.
        --------------------------------------------------------------------- */

        bd = &boards[crd];

        chan0 = card_ptr[crd];
        epcaassert(chan0 <= &digi_channels[nbdevs - 1], "ch out of range");

        assertgwinon(chan0);

        while ((tail = chan0->mailbox->eout) != (head = chan0->mailbox->ein)) 
        { /* Begin while something in event queue */

                assertgwinon(chan0);

                eventbuf = (volatile unchar *)bus_to_virt((ulong)(bd->re_map_membase + tail + ISTART));

                /* Get the channel the event occurred on */
                channel = eventbuf[0];

                /* Get the actual event code that occurred */
                event = eventbuf[1];

                /*  ----------------------------------------------------------------
                        The two assignments below get the current modem status (mstat)
                        and the previous modem status (lstat).  These are useful becuase
                        an event could signal a change in modem signals itself.
                ------------------------------------------------------------------- */

                mstat = eventbuf[2];
                lstat = eventbuf[3];

                ch = chan0 + channel;

                if ((unsigned)channel >= bd->numports || !ch) 
                { 
                        if (channel >= bd->numports)
                                ch = chan0;
                        bc = ch->brdchan;
                        goto next;
                }

                if ((bc = ch->brdchan) == NULL)
                        goto next;

                if (event & DATA_IND) 
                { /* Begin DATA_IND */

                        receive_data(ch);
                        assertgwinon(ch);

                } /* End DATA_IND */
                /* else *//* Fix for DCD transition missed bug */
                if (event & MODEMCHG_IND) 
                { /* Begin MODEMCHG_IND */

                        /* A modem signal change has been indicated */

                        ch->imodem = mstat;

                        if (ch->asyncflags & ASYNC_CHECK_CD) 
                        {
                                if (mstat & ch->dcd)  /* We are now receiving dcd */
                                        wake_up_interruptible(&ch->open_wait);
                                else
                                        pc_sched_event(ch, EPCA_EVENT_HANGUP); /* No dcd; hangup */
                        }

                } /* End MODEMCHG_IND */

                tty = ch->tty;
                if (tty) 
                { /* Begin if valid tty */

                        if (event & BREAK_IND) 
                        { /* Begin if BREAK_IND */

                                /* A break has been indicated */

                                tty->flip.count++;
                                *tty->flip.flag_buf_ptr++ = TTY_BREAK;

                                *tty->flip.char_buf_ptr++ = 0;

                                tty_schedule_flip(tty); 

                        } /* End if BREAK_IND */
                        else
                        if (event & LOWTX_IND) 
                        { /* Begin LOWTX_IND */

                                if (ch->statusflags & LOWWAIT) 
                                { /* Begin if LOWWAIT */

                                        ch->statusflags &= ~LOWWAIT;
                                        if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
                                                  tty->ldisc.write_wakeup)
                                                (tty->ldisc.write_wakeup)(tty);
                                        wake_up_interruptible(&tty->write_wait);

                                } /* End if LOWWAIT */

                        } /* End LOWTX_IND */
                        else
                        if (event & EMPTYTX_IND) 
                        { /* Begin EMPTYTX_IND */

                                /* This event is generated by setup_empty_event */

                                ch->statusflags &= ~TXBUSY;
                                if (ch->statusflags & EMPTYWAIT) 
                                { /* Begin if EMPTYWAIT */

                                        ch->statusflags &= ~EMPTYWAIT;
                                        if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
                                                  tty->ldisc.write_wakeup)
                                                (tty->ldisc.write_wakeup)(tty);

                                        wake_up_interruptible(&tty->write_wait);

                                } /* End if EMPTYWAIT */

                        } /* End EMPTYTX_IND */

                } /* End if valid tty */


        next:
                globalwinon(ch);

                if (!bc)
                        printk(KERN_ERR "<Error> - bc == NULL in doevent!\n");
                else 
                        bc->idata = 1;

                chan0->mailbox->eout = (tail + 4) & (IMAX - ISTART - 4);
                globalwinon(chan0);

        } /* End while something in event queue */

} /* End doevent */

/* --------------------- Begin fepcmd  ------------------------ */

static void fepcmd(struct channel *ch, int cmd, int word_or_byte,
                   int byte2, int ncmds, int bytecmd)
{ /* Begin fepcmd */

        unchar *memaddr;
        unsigned int head, cmdTail, cmdStart, cmdMax;
        long count;
        int n;

        /* This is the routine in which commands may be passed to the card. */

        if (ch->board->status == DISABLED)
        {
                return;
        }

        assertgwinon(ch);

        /* Remember head (As well as max) is just an offset not a base addr */
        head = ch->mailbox->cin;

        /* cmdStart is a base address */
        cmdStart = ch->mailbox->cstart;

        /* ------------------------------------------------------------------
                We do the addition below because we do not want a max pointer 
                relative to cmdStart.  We want a max pointer that points at the 
                physical end of the command queue.
        -------------------------------------------------------------------- */

        cmdMax = (cmdStart + 4 + (ch->mailbox->cmax));

        memaddr = ch->board->re_map_membase;

        /* 
           The below command is necessary because newer kernels (2.1.x and
           up) do not have a 1:1 virtual to physical mapping.  The below
           call adjust for that.
        */

        memaddr = (unsigned char *)bus_to_virt((unsigned long)memaddr);

        if (head >= (cmdMax - cmdStart) || (head & 03)) 
        {
                printk(KERN_ERR "line %d: Out of range, cmd = %x, head = %x\n", __LINE__, 
              cmd, head);
                printk(KERN_ERR "line %d: Out of range, cmdMax = %x, cmdStart = %x\n", __LINE__, 
              cmdMax, cmdStart);
                return;
        }

        if (bytecmd) 
        {
                *(volatile unchar *)(memaddr + head + cmdStart + 0) = (unchar)cmd;

                *(volatile unchar *)(memaddr + head + cmdStart + 1) = (unchar)ch->channelnum;
                /* Below word_or_byte is bits to set */
                *(volatile unchar *)(memaddr + head + cmdStart + 2) = (unchar)word_or_byte;
                /* Below byte2 is bits to reset */
                *(volatile unchar *)(memaddr + head + cmdStart + 3) = (unchar)byte2;

        } 
        else 
        {
                *(volatile unchar *)(memaddr + head + cmdStart + 0) = (unchar)cmd;
                *(volatile unchar *)(memaddr + head + cmdStart + 1) = (unchar)ch->channelnum;
                *(volatile ushort*)(memaddr + head + cmdStart + 2) = (ushort)word_or_byte;
        }

        head = (head + 4) & (cmdMax - cmdStart - 4);
        ch->mailbox->cin = head;

        count = FEPTIMEOUT;

        for (;;) 
        { /* Begin forever loop */

                count--;
                if (count == 0) 
                {
                        printk(KERN_ERR "<Error> - Fep not responding in fepcmd()\n");
                        return;
                }

                head = ch->mailbox->cin;
                cmdTail = ch->mailbox->cout;

                n = (head - cmdTail) & (cmdMax - cmdStart - 4);

                /* ----------------------------------------------------------
                        Basically this will break when the FEP acknowledges the 
                        command by incrementing cmdTail (Making it equal to head).
                ------------------------------------------------------------- */

                if (n <= ncmds * (sizeof(short) * 4))
                        break; /* Well nearly forever :-) */

        } /* End forever loop */

} /* End fepcmd */

/* ---------------------------------------------------------------------
        Digi products use fields in their channels structures that are very
        similar to the c_cflag and c_iflag fields typically found in UNIX
        termios structures.  The below three routines allow mappings 
        between these hardware "flags" and their respective Linux flags.
------------------------------------------------------------------------- */
 
/* --------------------- Begin termios2digi_h -------------------- */

static unsigned termios2digi_h(struct channel *ch, unsigned cflag)
{ /* Begin termios2digi_h */

        unsigned res = 0;

        if (cflag & CRTSCTS) 
        {
                ch->digiext.digi_flags |= (RTSPACE | CTSPACE);
                res |= ((ch->m_cts) | (ch->m_rts));
        }

        if (ch->digiext.digi_flags & RTSPACE)
                res |= ch->m_rts;

        if (ch->digiext.digi_flags & DTRPACE)
                res |= ch->m_dtr;

        if (ch->digiext.digi_flags & CTSPACE)
                res |= ch->m_cts;

        if (ch->digiext.digi_flags & DSRPACE)
                res |= ch->dsr;

        if (ch->digiext.digi_flags & DCDPACE)
                res |= ch->dcd;

        if (res & (ch->m_rts))
                ch->digiext.digi_flags |= RTSPACE;

        if (res & (ch->m_cts))
                ch->digiext.digi_flags |= CTSPACE;

        return res;

} /* End termios2digi_h */

/* --------------------- Begin termios2digi_i -------------------- */
static unsigned termios2digi_i(struct channel *ch, unsigned iflag)
{ /* Begin termios2digi_i */

        unsigned res = iflag & (IGNBRK | BRKINT | IGNPAR | PARMRK | 
                                INPCK | ISTRIP|IXON|IXANY|IXOFF);
        
        if (ch->digiext.digi_flags & DIGI_AIXON)
                res |= IAIXON;
        return res;

} /* End termios2digi_i */

/* --------------------- Begin termios2digi_c -------------------- */

static unsigned termios2digi_c(struct channel *ch, unsigned cflag)
{ /* Begin termios2digi_c */

        unsigned res = 0;

#ifdef SPEED_HACK
        /* CL: HACK to force 115200 at 38400 and 57600 at 19200 Baud */
        if ((cflag & CBAUD)== B38400) cflag=cflag - B38400 + B115200;
        if ((cflag & CBAUD)== B19200) cflag=cflag - B19200 + B57600;
#endif /* SPEED_HACK */

        if (cflag & CBAUDEX)
        { /* Begin detected CBAUDEX */

                ch->digiext.digi_flags |= DIGI_FAST;

                /* -------------------------------------------------------------
                   HUPCL bit is used by FEP to indicate fast baud
                   table is to be used.
                ----------------------------------------------------------------- */

                res |= FEP_HUPCL;

        } /* End detected CBAUDEX */
        else ch->digiext.digi_flags &= ~DIGI_FAST; 

        /* -------------------------------------------------------------------
                CBAUD has bit position 0x1000 set these days to indicate Linux
                baud rate remap.  Digi hardware can't handle the bit assignment.
                (We use a different bit assignment for high speed.).  Clear this
                bit out.
        ---------------------------------------------------------------------- */
        res |= cflag & ((CBAUD ^ CBAUDEX) | PARODD | PARENB | CSTOPB | CSIZE);

        /* -------------------------------------------------------------
                This gets a little confusing.  The Digi cards have their own
                representation of c_cflags controling baud rate.  For the most
                part this is identical to the Linux implementation.  However;
                Digi supports one rate (76800) that Linux doesn't.  This means 
                that the c_cflag entry that would normally mean 76800 for Digi
                actually means 115200 under Linux.  Without the below mapping,
                a stty 115200 would only drive the board at 76800.  Since 
                the rate 230400 is also found after 76800, the same problem afflicts    
                us when we choose a rate of 230400.  Without the below modificiation
                stty 230400 would actually give us 115200.

                There are two additional differences.  The Linux value for CLOCAL
                (0x800; 0004000) has no meaning to the Digi hardware.  Also in 
                later releases of Linux; the CBAUD define has CBAUDEX (0x1000;
                0010000) ored into it (CBAUD = 0x100f as opposed to 0xf). CBAUDEX
                should be checked for a screened out prior to termios2digi_c 
                returning.  Since CLOCAL isn't used by the board this can be
                ignored as long as the returned value is used only by Digi hardware. 
        ----------------------------------------------------------------- */

        if (cflag & CBAUDEX)
        {
                /* -------------------------------------------------------------
                        The below code is trying to guarantee that only baud rates
                        115200 and 230400 are remapped.  We use exclusive or because
                        the various baud rates share common bit positions and therefore
                        can't be tested for easily.
                ----------------------------------------------------------------- */

                                
                if ((!((cflag & 0x7) ^ (B115200 & ~CBAUDEX))) || 
                    (!((cflag & 0x7) ^ (B230400 & ~CBAUDEX))))
                {
                        res += 1;
                }
        }

        return res;

} /* End termios2digi_c */

/* --------------------- Begin epcaparam  ----------------------- */

static void epcaparam(struct tty_struct *tty, struct channel *ch)
{ /* Begin epcaparam */

        unsigned int cmdHead;
        struct termios *ts;
        volatile struct board_chan *bc;
        unsigned mval, hflow, cflag, iflag;

        bc = ch->brdchan;
        epcaassert(bc !=0, "bc out of range");

        assertgwinon(ch);

        ts = tty->termios;

        if ((ts->c_cflag & CBAUD) == 0) 
        { /* Begin CBAUD detected */

                cmdHead = bc->rin;
                bc->rout = cmdHead;
                cmdHead = bc->tin;

                /* Changing baud in mid-stream transmission can be wonderful */
                /* ---------------------------------------------------------------
                        Flush current transmit buffer by setting cmdTail pointer (tout)
                        to cmdHead pointer (tin).  Hopefully the transmit buffer is empty.
                ----------------------------------------------------------------- */

                fepcmd(ch, STOUT, (unsigned) cmdHead, 0, 0, 0);
                mval = 0;

        } /* End CBAUD detected */
        else 
        { /* Begin CBAUD not detected */

                /* -------------------------------------------------------------------
                        c_cflags have changed but that change had nothing to do with BAUD.
                        Propagate the change to the card.
                ---------------------------------------------------------------------- */ 

                cflag = termios2digi_c(ch, ts->c_cflag);

                if (cflag != ch->fepcflag) 
                {
                        ch->fepcflag = cflag;
                        /* Set baud rate, char size, stop bits, parity */
                        fepcmd(ch, SETCTRLFLAGS, (unsigned) cflag, 0, 0, 0);
                }


                /* ----------------------------------------------------------------
                        If the user has not forced CLOCAL and if the device is not a 
                        CALLOUT device (Which is always CLOCAL) we set flags such that
                        the driver will wait on carrier detect.
                ------------------------------------------------------------------- */

                if ((ts->c_cflag & CLOCAL) || (tty->driver.subtype == SERIAL_TYPE_CALLOUT))
                { /* Begin it is a cud device or a ttyD device with CLOCAL on */
                        ch->asyncflags &= ~ASYNC_CHECK_CD;
                } /* End it is a cud device or a ttyD device with CLOCAL on */
                else
                { /* Begin it is a ttyD device */
                        ch->asyncflags |= ASYNC_CHECK_CD;
                } /* End it is a ttyD device */

                mval = ch->m_dtr | ch->m_rts;

        } /* End CBAUD not detected */

        iflag = termios2digi_i(ch, ts->c_iflag);

        /* Check input mode flags */

        if (iflag != ch->fepiflag) 
        {
                ch->fepiflag = iflag;

                /* ---------------------------------------------------------------
                        Command sets channels iflag structure on the board. Such things 
                        as input soft flow control, handeling of parity errors, and
                        break handeling are all set here.
                ------------------------------------------------------------------- */

                /* break handeling, parity handeling, input stripping, flow control chars */
                fepcmd(ch, SETIFLAGS, (unsigned int) ch->fepiflag, 0, 0, 0);
        }

        /* ---------------------------------------------------------------
                Set the board mint value for this channel.  This will cause hardware
                events to be generated each time the DCD signal (Described in mint) 
                changes.        
        ------------------------------------------------------------------- */
        bc->mint = ch->dcd;

        if ((ts->c_cflag & CLOCAL) || (ch->digiext.digi_flags & DIGI_FORCEDCD))
                if (ch->digiext.digi_flags & DIGI_FORCEDCD)
                        bc->mint = 0;

        ch->imodem = bc->mstat;

        hflow = termios2digi_h(ch, ts->c_cflag);

        if (hflow != ch->hflow) 
        {
                ch->hflow = hflow;

                /* --------------------------------------------------------------
                        Hard flow control has been selected but the board is not
                        using it.  Activate hard flow control now.
                ----------------------------------------------------------------- */

                fepcmd(ch, SETHFLOW, hflow, 0xff, 0, 1);
        }
        

        mval ^= ch->modemfake & (mval ^ ch->modem);

        if (ch->omodem ^ mval) 
        {
                ch->omodem = mval;

                /* --------------------------------------------------------------
                        The below command sets the DTR and RTS mstat structure.  If
                        hard flow control is NOT active these changes will drive the
                        output of the actual DTR and RTS lines.  If hard flow control 
                        is active, the changes will be saved in the mstat structure and
                        only asserted when hard flow control is turned off. 
                ----------------------------------------------------------------- */

                /* First reset DTR & RTS; then set them */
                fepcmd(ch, SETMODEM, 0, ((ch->m_dtr)|(ch->m_rts)), 0, 1);
                fepcmd(ch, SETMODEM, mval, 0, 0, 1);

        }

        if (ch->startc != ch->fepstartc || ch->stopc != ch->fepstopc) 
        {
                ch->fepstartc = ch->startc;
                ch->fepstopc = ch->stopc;

                /* ------------------------------------------------------------
                        The XON / XOFF characters have changed; propogate these
                        changes to the card.    
                --------------------------------------------------------------- */

                fepcmd(ch, SONOFFC, ch->fepstartc, ch->fepstopc, 0, 1);
        }

        if (ch->startca != ch->fepstartca || ch->stopca != ch->fepstopca) 
        {
                ch->fepstartca = ch->startca;
                ch->fepstopca = ch->stopca;

                /* ---------------------------------------------------------------
                        Similar to the above, this time the auxilarly XON / XOFF 
                        characters have changed; propogate these changes to the card.
                ------------------------------------------------------------------ */

                fepcmd(ch, SAUXONOFFC, ch->fepstartca, ch->fepstopca, 0, 1);
        }

} /* End epcaparam */

/* --------------------- Begin receive_data  ----------------------- */

static void receive_data(struct channel *ch)
{ /* Begin receive_data */

        unchar *rptr;
        struct termios *ts = 0;
        struct tty_struct *tty;
        volatile struct board_chan *bc;
        register int dataToRead, wrapgap, bytesAvailable;
        register unsigned int tail, head;
        unsigned int wrapmask;
        int rc;


        /* ---------------------------------------------------------------
                This routine is called by doint when a receive data event 
                has taken place.
        ------------------------------------------------------------------- */

        globalwinon(ch);

        if (ch->statusflags & RXSTOPPED)
                return;

        tty = ch->tty;
        if (tty)
                ts = tty->termios;

        bc = ch->brdchan;

        if (!bc) 
        {
                printk(KERN_ERR "<Error> - bc is NULL in receive_data!\n");
                return;
        }

        wrapmask = ch->rxbufsize - 1;

        /* --------------------------------------------------------------------- 
                Get the head and tail pointers to the receiver queue.  Wrap the 
                head pointer if it has reached the end of the buffer.
        ------------------------------------------------------------------------ */

        head = bc->rin;
        head &= wrapmask;
        tail = bc->rout & wrapmask;

        bytesAvailable = (head - tail) & wrapmask;

        if (bytesAvailable == 0)
                return;

        /* ------------------------------------------------------------------
           If CREAD bit is off or device not open, set TX tail to head
        --------------------------------------------------------------------- */

        if (!tty || !ts || !(ts->c_cflag & CREAD)) 
        {
                bc->rout = head;
                return;
        }

        if (tty->flip.count == TTY_FLIPBUF_SIZE) 
                return;

        if (bc->orun) 
        {
                bc->orun = 0;
                printk(KERN_WARNING "overrun! DigiBoard device minor = %d\n",MINOR(tty->device));
        }

        rxwinon(ch);
        rptr = tty->flip.char_buf_ptr;
        rc = tty->flip.count;

        while (bytesAvailable > 0) 
        { /* Begin while there is data on the card */

                wrapgap = (head >= tail) ? head - tail : ch->rxbufsize - tail;

                /* ---------------------------------------------------------------
                        Even if head has wrapped around only report the amount of
                        data to be equal to the size - tail.  Remember memcpy can't
                        automaticly wrap around the receive buffer.
                ----------------------------------------------------------------- */

                dataToRead = (wrapgap < bytesAvailable) ? wrapgap : bytesAvailable;

                /* --------------------------------------------------------------
                   Make sure we don't overflow the buffer
                ----------------------------------------------------------------- */

                if ((rc + dataToRead) > TTY_FLIPBUF_SIZE)
                        dataToRead = TTY_FLIPBUF_SIZE - rc;

                if (dataToRead == 0)
                        break;

                /* ---------------------------------------------------------------
                        Move data read from our card into the line disciplines buffer
                        for translation if necessary.
                ------------------------------------------------------------------ */

                if ((memcpy(rptr, ch->rxptr + tail, dataToRead)) != rptr)
                        printk(KERN_ERR "<Error> - receive_data : memcpy failed\n");
                        
                rc   += dataToRead;
                rptr += dataToRead;
                tail = (tail + dataToRead) & wrapmask;
                bytesAvailable -= dataToRead;

        } /* End while there is data on the card */


        tty->flip.count = rc;
        tty->flip.char_buf_ptr = rptr;
        globalwinon(ch);
        bc->rout = tail;

        /* Must be called with global data */
        tty_schedule_flip(ch->tty); 
        return;

} /* End receive_data */

/* --------------------- Begin pc_ioctl  ----------------------- */

static int pc_ioctl(struct tty_struct *tty, struct file * file,
                    unsigned int cmd, unsigned long arg)
{ /* Begin pc_ioctl */

        digiflow_t dflow;
        int retval, error;
        unsigned long flags;
        unsigned int mflag, mstat;
        unsigned char startc, stopc;
        volatile struct board_chan *bc;
        struct channel *ch = (struct channel *) tty->driver_data;
        
        /* The control device has it's own set of commands */
        if (tty->driver.subtype == SERIAL_TYPE_INFO) 
        { /* Begin if subtype is the control device */

                switch (cmd) 
                { /* Begin switch cmd */

                        case DIGI_GETINFO:
                        { /* Begin case DIGI_GETINFO */

                                struct digi_info di ;
                                int brd;

                                getUser(brd, (unsigned int *)arg);

                                if ((error = verify_area(VERIFY_WRITE, (char*)arg, sizeof(di))))
                                {
                                        printk(KERN_ERR "DIGI_GETINFO : verify area size 0x%x failed\n",sizeof(di));
                                        return(error);
                                }

                                if ((brd < 0) || (brd >= num_cards) || (num_cards == 0))
                                        return (-ENODEV);

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

                                di.board = brd ; 
                                di.status = boards[brd].status;
                                di.type = boards[brd].type ;
                                di.numports = boards[brd].numports ;
                                di.port = boards[brd].port ;
                                di.membase = boards[brd].membase ;

                                if (copy_to_user((char *)arg, &di, sizeof (di)))
                                        return -EFAULT;
                                break;

                        } /* End case DIGI_GETINFO */

                        case DIGI_POLLER:
                        { /* Begin case DIGI_POLLER */

                                int brd = arg & 0xff000000 >> 16 ; 
                                unsigned char state = arg & 0xff ; 

                                if ((brd < 0) || (brd >= num_cards))
                                {
                                        printk(KERN_ERR "<Error> - DIGI POLLER : brd not valid!\n");
                                        return (-ENODEV);
                                }

                                digi_poller_inhibited = state ;
                                break ; 

                        } /* End case DIGI_POLLER */

                        case DIGI_INIT:
                        { /* Begin case DIGI_INIT */

                                /* ------------------------------------------------------------
                                        This call is made by the apps to complete the initilization
                                        of the board(s).  This routine is responsible for setting
                                        the card to its initial state and setting the drivers control
                                        fields to the sutianle settings for the card in question.
                                ---------------------------------------------------------------- */
                        
                                int crd ; 
                                for (crd = 0; crd < num_cards; crd++) 
                                        post_fep_init (crd);

                                break ; 

                        } /* End case DIGI_INIT */


                        default:
                                return -ENOIOCTLCMD;

                } /* End switch cmd */
                return (0) ;

        } /* End if subtype is the control device */

        if (ch)
                bc = ch->brdchan;
        else 
        {
                printk(KERN_ERR "<Error> - ch is NULL in pc_ioctl!\n");
                return(-EINVAL);
        }

        save_flags(flags);

        /* -------------------------------------------------------------------
                For POSIX compliance we need to add more ioctls.  See tty_ioctl.c
                in /usr/src/linux/drivers/char for a good example.  In particular 
                think about adding TCSETAF, TCSETAW, TCSETA, TCSETSF, TCSETSW, TCSETS.
        ---------------------------------------------------------------------- */

        switch (cmd) 
        { /* Begin switch cmd */

                case TCGETS:
                        if (copy_to_user((struct termios *)arg, 
                                         tty->termios, sizeof(struct termios)))
                                return -EFAULT;
                        return(0);

                case TCGETA:
                        return get_termio(tty, (struct termio *)arg);

                case TCSBRK:    /* SVID version: non-zero arg --> no break */

                        retval = tty_check_change(tty);
                        if (retval)
                                return retval;

                        /* Setup an event to indicate when the transmit buffer empties */

                        setup_empty_event(tty,ch);              
                        tty_wait_until_sent(tty, 0);
                        if (!arg)
                                digi_send_break(ch, HZ/4);    /* 1/4 second */
                        return 0;

                case TCSBRKP:   /* support for POSIX tcsendbreak() */

                        retval = tty_check_change(tty);
                        if (retval)
                                return retval;

                        /* Setup an event to indicate when the transmit buffer empties */

                        setup_empty_event(tty,ch);              
                        tty_wait_until_sent(tty, 0);
                        digi_send_break(ch, arg ? arg*(HZ/10) : HZ/4);
                        return 0;

                case TIOCGSOFTCAR:

                        error = verify_area(VERIFY_WRITE, (void *) arg,sizeof(long));
                        if (error)
                                return error;

                        putUser(C_CLOCAL(tty) ? 1 : 0,
                                    (unsigned long *) arg);
                        return 0;

                case TIOCSSOFTCAR:
                        /*RONNIE PUT VERIFY_READ (See above) check here */
                {
                        unsigned int value;

                        getUser(value, (unsigned int *)arg);
                        tty->termios->c_cflag =
                                ((tty->termios->c_cflag & ~CLOCAL) |
                                 (value ? CLOCAL : 0));
                        return 0;
                }

                case TIOCMODG:
                case TIOCMGET:

                        mflag = 0;

                        cli();
                        globalwinon(ch);
                        mstat = bc->mstat;
                        memoff(ch);
                        restore_flags(flags);

                        if (mstat & ch->m_dtr)
                                mflag |= TIOCM_DTR;

                        if (mstat & ch->m_rts)
                                mflag |= TIOCM_RTS;

                        if (mstat & ch->m_cts)
                                mflag |= TIOCM_CTS;

                        if (mstat & ch->dsr)
                                mflag |= TIOCM_DSR;

                        if (mstat & ch->m_ri)
                                mflag |= TIOCM_RI;

                        if (mstat & ch->dcd)
                                mflag |= TIOCM_CD;

                        error = verify_area(VERIFY_WRITE, (void *) arg,sizeof(long));

                        if (error)
                                return error;

                        putUser(mflag, (unsigned int *) arg);

                        break;

                case TIOCMBIS:
                case TIOCMBIC:
                case TIOCMODS:
                case TIOCMSET:

                        getUser(mstat, (unsigned int *)arg);

                        mflag = 0;
                        if (mstat & TIOCM_DTR)
                                mflag |= ch->m_dtr;

                        if (mstat & TIOCM_RTS)
                                mflag |= ch->m_rts;

                        switch (cmd) 
                        { /* Begin switch cmd */

                                case TIOCMODS:
                                case TIOCMSET:
                                        ch->modemfake = ch->m_dtr|ch->m_rts;
                                        ch->modem = mflag;
                                        break;

                                case TIOCMBIS:
                                        ch->modemfake |= mflag;
                                        ch->modem |= mflag;
                                        break;

                                case TIOCMBIC:
                                        ch->modemfake |= mflag;
                                        ch->modem &= ~mflag;
                                        break;

                        } /* End switch cmd */

                        cli();
                        globalwinon(ch);

                        /*  --------------------------------------------------------------
                                The below routine generally sets up parity, baud, flow control 
                                issues, etc.... It effect both control flags and input flags.
                        ------------------------------------------------------------------ */

                        epcaparam(tty,ch);
                        memoff(ch);
                        restore_flags(flags);
                        break;

                case TIOCSDTR:
                        ch->omodem |= ch->m_dtr;
                        cli();
                        globalwinon(ch);
                        fepcmd(ch, SETMODEM, ch->m_dtr, 0, 10, 1);
                        memoff(ch);
                        restore_flags(flags);
                        break;

                case TIOCCDTR:
                        ch->omodem &= ~ch->m_dtr;
                        cli();
                        globalwinon(ch);
                        fepcmd(ch, SETMODEM, 0, ch->m_dtr, 10, 1);
                        memoff(ch);
                        restore_flags(flags);
                        break;

                case DIGI_GETA:
                        if (copy_to_user((char*)arg, &ch->digiext,
                                         sizeof(digi_t)))
                                return -EFAULT;
                        break;

                case DIGI_SETAW:
                case DIGI_SETAF:
                        if ((cmd) == (DIGI_SETAW)) 
                        {
                                /* Setup an event to indicate when the transmit buffer empties */

                                setup_empty_event(tty,ch);              
                                tty_wait_until_sent(tty, 0);
                        }
                        else 
                        {
                                if (tty->ldisc.flush_buffer)
                                        tty->ldisc.flush_buffer(tty);
                        }

                        /* Fall Thru */

                case DIGI_SETA:
                        if (copy_from_user(&ch->digiext, (char*)arg,
                                           sizeof(digi_t)))
                                return -EFAULT;
                        
                        if (ch->digiext.digi_flags & DIGI_ALTPIN) 
                        {
                                ch->dcd = ch->m_dsr;
                                ch->dsr = ch->m_dcd;
                        } 
                        else 
                        {
                                ch->dcd = ch->m_dcd;
                                ch->dsr = ch->m_dsr;
                        }
                
                        cli();
                        globalwinon(ch);

                        /* -----------------------------------------------------------------
                                The below routine generally sets up parity, baud, flow control 
                                issues, etc.... It effect both control flags and input flags.
                        ------------------------------------------------------------------- */

                        epcaparam(tty,ch);
                        memoff(ch);
                        restore_flags(flags);
                        break;

                case DIGI_GETFLOW:
                case DIGI_GETAFLOW:
                        cli();  
                        globalwinon(ch);
                        if ((cmd) == (DIGI_GETFLOW)) 
                        {
                                dflow.startc = bc->startc;
                                dflow.stopc = bc->stopc;
                        }
                        else 
                        {
                                dflow.startc = bc->startca;
                                dflow.stopc = bc->stopca;
                        }
                        memoff(ch);
                        restore_flags(flags);

                        if (copy_to_user((char*)arg, &dflow, sizeof(dflow)))
                                return -EFAULT;
                        break;

                case DIGI_SETAFLOW:
                case DIGI_SETFLOW:
                        if ((cmd) == (DIGI_SETFLOW)) 
                        {
                                startc = ch->startc;
                                stopc = ch->stopc;
                        } 
                        else 
                        {
                                startc = ch->startca;
                                stopc = ch->stopca;
                        }

                        if (copy_from_user(&dflow, (char*)arg, sizeof(dflow)))
                                return -EFAULT;

                        if (dflow.startc != startc || dflow.stopc != stopc) 
                        { /* Begin  if setflow toggled */
                                cli();
                                globalwinon(ch);

                                if ((cmd) == (DIGI_SETFLOW)) 
                                {
                                        ch->fepstartc = ch->startc = dflow.startc;
                                        ch->fepstopc = ch->stopc = dflow.stopc;
                                        fepcmd(ch, SONOFFC, ch->fepstartc, ch->fepstopc, 0, 1);
                                } 
                                else 
                                {
                                        ch->fepstartca = ch->startca = dflow.startc;
                                        ch->fepstopca  = ch->stopca = dflow.stopc;
                                        fepcmd(ch, SAUXONOFFC, ch->fepstartca, ch->fepstopca, 0, 1);
                                }

                                if      (ch->statusflags & TXSTOPPED)
                                        pc_start(tty);

                                memoff(ch);
                                restore_flags(flags);

                        } /* End if setflow toggled */
                        break;

                default:
                        return -ENOIOCTLCMD;

        } /* End switch cmd */

        return 0;

} /* End pc_ioctl */

/* --------------------- Begin pc_set_termios  ----------------------- */

static void pc_set_termios(struct tty_struct *tty, struct termios *old_termios)
{ /* Begin pc_set_termios */

        struct channel *ch;
        unsigned long flags;

        /* ---------------------------------------------------------
                verifyChannel returns the channel from the tty struct
                if it is valid.  This serves as a sanity check.
        ------------------------------------------------------------- */

        if ((ch = verifyChannel(tty)) != NULL) 
        { /* Begin if channel valid */

                save_flags(flags);
                cli();
                globalwinon(ch);
                epcaparam(tty, ch);
                memoff(ch);

                if ((old_termios->c_cflag & CRTSCTS) &&
                         ((tty->termios->c_cflag & CRTSCTS) == 0))
                        tty->hw_stopped = 0;

                if (!(old_termios->c_cflag & CLOCAL) &&
                         (tty->termios->c_cflag & CLOCAL))
                        wake_up_interruptible(&ch->open_wait);

                restore_flags(flags);

        } /* End if channel valid */

} /* End pc_set_termios */

/* --------------------- Begin do_softint  ----------------------- */

static void do_softint(void *private_)
{ /* Begin do_softint */

        struct channel *ch = (struct channel *) private_;
        

        /* Called in response to a modem change event */

        if (ch && ch->magic == EPCA_MAGIC) 
        { /* Begin EPCA_MAGIC */

                struct tty_struct *tty = ch->tty;

                if (tty && tty->driver_data) 
                { 
                        if (test_and_clear_bit(EPCA_EVENT_HANGUP, &ch->event)) 
                        { /* Begin if clear_bit */

                                tty_hangup(tty);        /* FIXME: module removal race here - AKPM */
                                wake_up_interruptible(&ch->open_wait);
                                ch->asyncflags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_CALLOUT_ACTIVE);

                        } /* End if clear_bit */
                }

        } /* End EPCA_MAGIC */
        MOD_DEC_USE_COUNT;
} /* End do_softint */

/* ------------------------------------------------------------
        pc_stop and pc_start provide software flow control to the 
        routine and the pc_ioctl routine.
---------------------------------------------------------------- */

/* --------------------- Begin pc_stop  ----------------------- */

static void pc_stop(struct tty_struct *tty)
{ /* Begin pc_stop */

        struct channel *ch;
        unsigned long flags;

        /* ---------------------------------------------------------
                verifyChannel returns the channel from the tty struct
                if it is valid.  This serves as a sanity check.
        ------------------------------------------------------------- */

        if ((ch = verifyChannel(tty)) != NULL) 
        { /* Begin if valid channel */

                save_flags(flags); 
                cli();

                if ((ch->statusflags & TXSTOPPED) == 0) 
                { /* Begin if transmit stop requested */

                        globalwinon(ch);

                        /* STOP transmitting now !! */

                        fepcmd(ch, PAUSETX, 0, 0, 0, 0);

                        ch->statusflags |= TXSTOPPED;
                        memoff(ch);

                } /* End if transmit stop requested */

                restore_flags(flags);

        } /* End if valid channel */

} /* End pc_stop */

/* --------------------- Begin pc_start  ----------------------- */

static void pc_start(struct tty_struct *tty)
{ /* Begin pc_start */

        struct channel *ch;

        /* ---------------------------------------------------------
                verifyChannel returns the channel from the tty struct
                if it is valid.  This serves as a sanity check.
        ------------------------------------------------------------- */

        if ((ch = verifyChannel(tty)) != NULL) 
        { /* Begin if channel valid */

                unsigned long flags;

                save_flags(flags);
                cli();

                /* Just in case output was resumed because of a change in Digi-flow */
                if (ch->statusflags & TXSTOPPED) 
                { /* Begin transmit resume requested */

                        volatile struct board_chan *bc;

                        globalwinon(ch);
                        bc = ch->brdchan;
                        if (ch->statusflags & LOWWAIT)
                                bc->ilow = 1;

                        /* Okay, you can start transmitting again... */

                        fepcmd(ch, RESUMETX, 0, 0, 0, 0);

                        ch->statusflags &= ~TXSTOPPED;
                        memoff(ch);

                } /* End transmit resume requested */

                restore_flags(flags);

        } /* End if channel valid */

} /* End pc_start */

/* ------------------------------------------------------------------
        The below routines pc_throttle and pc_unthrottle are used 
        to slow (And resume) the receipt of data into the kernels
        receive buffers.  The exact occurence of this depends on the
        size of the kernels receive buffer and what the 'watermarks'
        are set to for that buffer.  See the n_ttys.c file for more
        details. 
______________________________________________________________________ */
/* --------------------- Begin throttle  ----------------------- */

static void pc_throttle(struct tty_struct * tty)
{ /* Begin pc_throttle */

        struct channel *ch;
        unsigned long flags;

        /* ---------------------------------------------------------
                verifyChannel returns the channel from the tty struct
                if it is valid.  This serves as a sanity check.
        ------------------------------------------------------------- */

        if ((ch = verifyChannel(tty)) != NULL) 
        { /* Begin if channel valid */


                save_flags(flags);
                cli();

                if ((ch->statusflags & RXSTOPPED) == 0)
                {
                        globalwinon(ch);
                        fepcmd(ch, PAUSERX, 0, 0, 0, 0);

                        ch->statusflags |= RXSTOPPED;
                        memoff(ch);
                }
                restore_flags(flags);

        } /* End if channel valid */

} /* End pc_throttle */

/* --------------------- Begin unthrottle  ----------------------- */

static void pc_unthrottle(struct tty_struct *tty)
{ /* Begin pc_unthrottle */

        struct channel *ch;
        unsigned long flags;
        volatile struct board_chan *bc;


        /* ---------------------------------------------------------
                verifyChannel returns the channel from the tty struct
                if it is valid.  This serves as a sanity check.
        ------------------------------------------------------------- */

        if ((ch = verifyChannel(tty)) != NULL) 
        { /* Begin if channel valid */


                /* Just in case output was resumed because of a change in Digi-flow */
                save_flags(flags);
                cli();

                if (ch->statusflags & RXSTOPPED) 
                {

                        globalwinon(ch);
                        bc = ch->brdchan;
                        fepcmd(ch, RESUMERX, 0, 0, 0, 0);

                        ch->statusflags &= ~RXSTOPPED;
                        memoff(ch);
                }
                restore_flags(flags);

        } /* End if channel valid */

} /* End pc_unthrottle */

/* --------------------- Begin digi_send_break  ----------------------- */

void digi_send_break(struct channel *ch, int msec)
{ /* Begin digi_send_break */

        unsigned long flags;

        save_flags(flags);
        cli();
        globalwinon(ch);

        /* -------------------------------------------------------------------- 
           Maybe I should send an infinite break here, schedule() for
           msec amount of time, and then stop the break.  This way,
           the user can't screw up the FEP by causing digi_send_break()
           to be called (i.e. via an ioctl()) more than once in msec amount 
           of time.  Try this for now...
        ------------------------------------------------------------------------ */

        fepcmd(ch, SENDBREAK, msec, 0, 10, 0);
        memoff(ch);

        restore_flags(flags);

} /* End digi_send_break */

/* --------------------- Begin setup_empty_event  ----------------------- */

static void setup_empty_event(struct tty_struct *tty, struct channel *ch)
{ /* Begin setup_empty_event */

        volatile struct board_chan *bc = ch->brdchan;
        unsigned long int flags;

        save_flags(flags);
        cli();
        globalwinon(ch);
        ch->statusflags |= EMPTYWAIT;
        
        /* ------------------------------------------------------------------
                When set the iempty flag request a event to be generated when the 
                transmit buffer is empty (If there is no BREAK in progress).
        --------------------------------------------------------------------- */

        bc->iempty = 1;
        memoff(ch);
        restore_flags(flags);

} /* End setup_empty_event */

/* --------------------- Begin get_termio ----------------------- */

static int get_termio(struct tty_struct * tty, struct termio * termio)
{ /* Begin get_termio */
        int error;

        error = verify_area(VERIFY_WRITE, termio, sizeof (struct termio));
        if (error)
                return error;

        kernel_termios_to_user_termio(termio, tty->termios);

        return 0;
} /* End get_termio */
/* ---------------------- Begin epca_setup  -------------------------- */
void epca_setup(char *str, int *ints)
{ /* Begin epca_setup */

        struct board_info board;
        int               index, loop, last;
        char              *temp, *t2;
        unsigned          len;

        /* ----------------------------------------------------------------------
                If this routine looks a little strange it is because it is only called
                if a LILO append command is given to boot the kernel with parameters.  
                In this way, we can provide the user a method of changing his board
                configuration without rebuilding the kernel.
        ----------------------------------------------------------------------- */
        if (!liloconfig) 
                liloconfig = 1; 

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

        /* Assume the data is int first, later we can change it */
        /* I think that array position 0 of ints holds the number of args */
        for (last = 0, index = 1; index <= ints[0]; index++)
                switch(index)
                { /* Begin parse switch */

                        case 1:
                                board.status = ints[index];
                                
                                /* ---------------------------------------------------------
                                        We check for 2 (As opposed to 1; because 2 is a flag
                                        instructing the driver to ignore epcaconfig.)  For this
                                        reason we check for 2.
                                ------------------------------------------------------------ */ 
                                if (board.status == 2)
                                { /* Begin ignore epcaconfig as well as lilo cmd line */
                                        nbdevs = 0;
                                        num_cards = 0;
                                        return;
                                } /* End ignore epcaconfig as well as lilo cmd line */
        
                                if (board.status > 2)
                                {
                                        printk(KERN_ERR "<Error> - epca_setup: Invalid board status 0x%x\n", board.status);
                                        invalid_lilo_config = 1;
                                        setup_error_code |= INVALID_BOARD_STATUS;
                                        return;
                                }
                                last = index;
                                break;

                        case 2:
                                board.type = ints[index];
                                if (board.type >= PCIXEM) 
                                {
                                        printk(KERN_ERR "<Error> - epca_setup: Invalid board type 0x%x\n", board.type);
                                        invalid_lilo_config = 1;
                                        setup_error_code |= INVALID_BOARD_TYPE;
                                        return;
                                }
                                last = index;
                                break;

                        case 3:
                                board.altpin = ints[index];
                                if (board.altpin > 1)
                                {
                                        printk(KERN_ERR "<Error> - epca_setup: Invalid board altpin 0x%x\n", board.altpin);
                                        invalid_lilo_config = 1;
                                        setup_error_code |= INVALID_ALTPIN;
                                        return;
                                }
                                last = index;
                                break;

                        case 4:
                                board.numports = ints[index];
                                if ((board.numports < 2) || (board.numports > 256))
                                {
                                        printk(KERN_ERR "<Error> - epca_setup: Invalid board numports 0x%x\n", board.numports);
                                        invalid_lilo_config = 1;
                                        setup_error_code |= INVALID_NUM_PORTS;
                                        return;
                                }
                                nbdevs += board.numports;
                                last = index;
                                break;

                        case 5:
                                board.port = (unsigned char *)ints[index];
                                if (ints[index] <= 0)
                                {
                                        printk(KERN_ERR "<Error> - epca_setup: Invalid io port 0x%x\n", (unsigned int)board.port);
                                        invalid_lilo_config = 1;
                                        setup_error_code |= INVALID_PORT_BASE;
                                        return;
                                }
                                last = index;
                                break;

                        case 6:
                                board.membase = (unsigned char *)ints[index];
                                if (ints[index] <= 0)
                                {
                                        printk(KERN_ERR "<Error> - epca_setup: Invalid memory base 0x%x\n",(unsigned int)board.membase);
                                        invalid_lilo_config = 1;
                                        setup_error_code |= INVALID_MEM_BASE;
                                        return;
                                }
                                last = index;
                                break;

                        default:
                                printk(KERN_ERR "<Error> - epca_setup: Too many integer parms\n");
                                return;

                } /* End parse switch */

        while (str && *str) 
        { /* Begin while there is a string arg */

                /* find the next comma or terminator */
                temp = str;

                /* While string is not null, and a comma hasn't been found */
                while (*temp && (*temp != ','))
                        temp++;

                if (!*temp)
                        temp = NULL;
                else
                        *temp++ = 0;

                /* Set index to the number of args + 1 */
                index = last + 1;

                switch(index)
                {
                        case 1:
                                len = strlen(str);
                                if (strncmp("Disable", str, len) == 0) 
                                        board.status = 0;
                                else
                                if (strncmp("Enable", str, len) == 0)
                                        board.status = 1;
                                else
                                {
                                        printk(KERN_ERR "<Error> - epca_setup: Invalid status %s\n", str);
                                        invalid_lilo_config = 1;
                                        setup_error_code |= INVALID_BOARD_STATUS;
                                        return;
                                }
                                last = index;
                                break;

                        case 2:

                                for(loop = 0; loop < EPCA_NUM_TYPES; loop++)
                                        if (strcmp(board_desc[loop], str) == 0)
                                                break;


                                /* ---------------------------------------------------------------
                                        If the index incremented above refers to a legitamate board 
                                        type set it here. 
                                ------------------------------------------------------------------*/

                                if (index < EPCA_NUM_TYPES) 
                                        board.type = loop;
                                else
                                {
                                        printk(KERN_ERR "<Error> - epca_setup: Invalid board type: %s\n", str);
                                        invalid_lilo_config = 1;
                                        setup_error_code |= INVALID_BOARD_TYPE;
                                        return;
                                }
                                last = index;
                                break;

                        case 3:
                                len = strlen(str);
                                if (strncmp("Disable", str, len) == 0) 
                                        board.altpin = 0;
                                else
                                if (strncmp("Enable", str, len) == 0)
                                        board.altpin = 1;
                                else
                                {
                                        printk(KERN_ERR "<Error> - epca_setup: Invalid altpin %s\n", str);
                                        invalid_lilo_config = 1;
                                        setup_error_code |= INVALID_ALTPIN;
                                        return;
                                }
                                last = index;
                                break;

                        case 4:
                                t2 = str;
                                while (isdigit(*t2))
                                        t2++;

                                if (*t2)
                                {
                                        printk(KERN_ERR "<Error> - epca_setup: Invalid port count %s\n", str);
                                        invalid_lilo_config = 1;
                                        setup_error_code |= INVALID_NUM_PORTS;
                                        return;
                                }

                                /* ------------------------------------------------------------
                                        There is not a man page for simple_strtoul but the code can be 
                                        found in vsprintf.c.  The first argument is the string to 
                                        translate (To an unsigned long obviously),  the second argument
                                        can be the address of any character variable or a NULL.  If a
                                        variable is given, the end pointer of the string will be stored 
                                        in that variable; if a NULL is given the end pointer will 
                                        not be returned.  The last argument is the base to use.  If 
                                        a 0 is indicated, the routine will attempt to determine the 
                                        proper base by looking at the values prefix (A '0' for octal,
                                        a 'x' for hex, etc ...  If a value is given it will use that 
                                        value as the base. 
                                ---------------------------------------------------------------- */ 
                                board.numports = simple_strtoul(str, NULL, 0);
                                nbdevs += board.numports;
                                last = index;
                                break;

                        case 5:
                                t2 = str;
                                while (isxdigit(*t2))
                                        t2++;

                                if (*t2)
                                {
                                        printk(KERN_ERR "<Error> - epca_setup: Invalid i/o address %s\n", str);
                                        invalid_lilo_config = 1;
                                        setup_error_code |= INVALID_PORT_BASE;
                                        return;
                                }

                                board.port = (unsigned char *)simple_strtoul(str, NULL, 16);
                                last = index;
                                break;

                        case 6:
                                t2 = str;
                                while (isxdigit(*t2))
                                        t2++;

                                if (*t2)
                                {
                                        printk(KERN_ERR "<Error> - epca_setup: Invalid memory base %s\n",str);
                                        invalid_lilo_config = 1;
                                        setup_error_code |= INVALID_MEM_BASE;
                                        return;
                                }

                                board.membase = (unsigned char *)simple_strtoul(str, NULL, 16);
                                last = index;
                                break;

                        default:
                                printk(KERN_ERR "PC/Xx: Too many string parms\n");
                                return;
                }
                str = temp;

        } /* End while there is a string arg */


        if (last < 6)  
        {
                printk(KERN_ERR "PC/Xx: Insufficient parms specified\n");
                return;
        }
 
        /* I should REALLY validate the stuff here */

        /* Copies our local copy of board into boards */
        memcpy((void *)&boards[num_cards],(void *)&board, sizeof(board));


        /* Does this get called once per lilo arg are what ? */

        printk(KERN_INFO "PC/Xx: Added board %i, %s %i ports at 0x%4.4X base 0x%6.6X\n", 
                num_cards, board_desc[board.type], 
                board.numports, (int)board.port, (unsigned int) board.membase);

        num_cards++;

} /* End epca_setup */



#ifdef ENABLE_PCI
/* ------------------------ Begin init_PCI  --------------------------- */

enum epic_board_types {
        brd_xr = 0,
        brd_xem,
        brd_cx,
        brd_xrj,
};


/* indexed directly by epic_board_types enum */
static struct {
        unsigned char board_type;
        unsigned bar_idx;               /* PCI base address region */
} epca_info_tbl[] = {
        { PCIXR, 0, },
        { PCIXEM, 0, },
        { PCICX, 0, },
        { PCIXRJ, 2, },
};


static int __init epca_init_one (struct pci_dev *pdev,
                                 const struct pci_device_id *ent)
{
        static int board_num = -1;
        int board_idx, info_idx = ent->driver_data;
        unsigned long addr;

        if (pci_enable_device(pdev))
                return -EIO;

        board_num++;
        board_idx = board_num + num_cards;
        if (board_idx >= MAXBOARDS)
                goto err_out;
        
        addr = pci_resource_start (pdev, epca_info_tbl[info_idx].bar_idx);