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[mascara-docs.git] / i386 / linux / linux-2.3.21 / drivers / char / tpqic02.c

/* $Id: tpqic02.c,v 1.10 1997/01/26 07:13:20 davem Exp $
 *
 * Driver for tape drive support for Linux-i386
 *
 * Copyright (c) 1992--1996 by H. H. Bergman. All rights reserved.
 * Current e-mail address: hennus@cybercomm.nl
 *
 * Distribution of this program in executable form is only allowed if
 * all of the corresponding source files are made available through the same
 * medium at no extra cost.
 *
 * I will not accept any responsibility for damage caused directly or
 * indirectly by this program, or code derived from this program.
 *
 * Use this code at your own risk. Don't blame me if it destroys your data!
 * Make sure you have a backup before you try this code.
 *
 * If you make changes to my code and redistribute it in source or binary
 * form you must make it clear to even casual users of your code that you
 * have modified my code, clearly point out what the changes exactly are
 * (preferably in the form of a context diff file), how to undo your changes,
 * where the original can be obtained, and that complaints/requests about the
 * modified code should be directed to you instead of me.
 *
 * This driver was partially inspired by the 'wt' driver in the 386BSD
 * source distribution, which carries the following copyright notice:
 *
 *  Copyright (c) 1991 The Regents of the University of California.
 *  All rights reserved.
 *
 * You are not allowed to change this line nor the text above.
 *
 * 1996/10/10   Emerald changes
 *
 * 1996/05/21   Misc changes+merges+cleanups + I/O reservations
 *
 * 1996/05/20   Module support patches submitted by Brian McCauley.
 *
 * 1994/05/03   Initial attempt at Mountain support for the Mountain 7150.
 * Based on patches provided by Erik Jacobson. Still incomplete, I suppose.
 *
 * 1994/02/07   Archive changes & some cleanups by Eddy Olk.
 *
 * 1994/01/19   Speed measuring stuff moved from aperf.h to delay.h.
 *              BogoMips (tm) introduced by Linus.
 *
 * 1993/01/25   Kernel udelay. Eof fixups.
 * 
 * 1992/09/19   Some changes based on patches by Eddy Olk to support
 *              Archive SC402/SC499R controller cards.
 *
 * 1992/05/27   First release.
 *
 * 1992/05/26   Initial version. Copyright H. H. Bergman 1992
 */

/* After the legalese, now the important bits:
 * 
 * This is a driver for the Wangtek 5150 tape drive with 
 * a QIC-02 controller for ISA-PC type computers.
 * Hopefully it will work with other QIC-02 tape drives as well.
 *
 * Make sure your setup matches the configuration parameters.
 * Also, be careful to avoid IO conflicts with other devices!
 */


/*
#define TDEBUG
*/

#define REALLY_SLOW_IO          /* it sure is ... */

#include <linux/module.h>

#include <linux/config.h>

#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/mtio.h>
#include <linux/fcntl.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/tpqic02.h>
#include <linux/mm.h>
#include <linux/malloc.h>
#include <linux/init.h>
 
#include <asm/dma.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/uaccess.h>

/* check existence of required configuration parameters */
#if !defined(QIC02_CMD_PORT) || !defined(QIC02_TAPE_IRQ) || !defined(QIC02_TAPE_DMA)
# error qic02_tape configuration error
#endif


#define TPQIC02_NAME    "tpqic02"

/* Linux outb() commands have (value,port) as parameters.
 * One might expect (port,value) instead, so beware!
 */

#ifdef CONFIG_QIC02_DYNCONF
/* This holds the dynamic configuration info for the interface
 * card+drive info if runtime configuration has been selected.
 */

static struct mtconfiginfo qic02_tape_dynconf =         /* user settable */
    { 0, 0, BOGUS_IRQ, 0, 0, TPQD_DEFAULT_FLAGS, };
static struct qic02_ccb qic02_tape_ccb = { 0, };        /* private stuff */

#else

unsigned long qic02_tape_debug = TPQD_DEFAULT_FLAGS;

# if ((QIC02_TAPE_IFC!=WANGTEK) && (QIC02_TAPE_IFC!=ARCHIVE) && (QIC02_TAPE_IFC!=MOUNTAIN))
#  error No valid interface card specified
# endif
#endif /* CONFIG_QIC02_DYNCONF */

static volatile int ctlbits = 0;     /* control reg bits for tape interface */

static wait_queue_head_t qic02_tape_transfer; /* sync rw with interrupts */

static volatile struct mtget ioctl_status;      /* current generic status */

static volatile struct tpstatus tperror;        /* last drive status */

static char rcs_revision[] = "$Revision: 1.10 $";
static char rcs_date[] = "$Date: 1997/01/26 07:13:20 $";

/* Flag bits for status and outstanding requests.
 * (Could all be put in one bit-field-struct.)
 * Some variables need `volatile' because they may be modified
 * by an interrupt.
 */
static volatile flag status_dead = YES; /* device is legally dead until proven alive */
static          flag status_zombie = YES; /* it's `zombie' until irq/dma allocated */

static volatile flag status_bytes_wr = NO;      /* write FM at close or not */
static volatile flag status_bytes_rd = NO;      /* (rd|wr) used for rewinding */

static volatile unsigned long status_cmd_pending = 0; /* cmd in progress */
static volatile flag status_expect_int = NO;    /* ready for interrupts */
static volatile flag status_timer_on = NO;      /* using time-out */
static volatile int  status_error = 0;          /* int handler may detect error */
static volatile flag status_eof_detected = NO;  /* end of file */
static volatile flag status_eom_detected = NO;  /* end of recorded media */
static volatile flag status_eot_detected = NO;  /* end of tape */
static volatile flag doing_read = NO;
static volatile flag doing_write = NO;

static volatile unsigned long dma_bytes_todo;
static volatile unsigned long dma_bytes_done;
static volatile unsigned dma_mode = 0;          /* !=0 also means DMA in use */
static          flag need_rewind = YES;

static kdev_t current_tape_dev;
static int extra_blocks_left = BLOCKS_BEYOND_EW;


/* return_*_eof:
 *      NO:     not at EOF,
 *      YES:    tell app EOF was reached (return 0).
 *
 * return_*_eof==YES && reported_*_eof==NO  ==>
 *      return current buffer, next time(s) return EOF.
 *
 * return_*_eof==YES && reported_*_eof==YES  ==>
 *      at EOF and application knows it, so we can
 *      move on to the next file.
 *
 */
static flag return_read_eof = NO;       /* set to signal app EOF was reached */
static flag return_write_eof = NO;
static flag reported_read_eof = NO;     /* set when we've done that */
static flag reported_write_eof = NO;


/* This is for doing `mt seek <blocknr>' */
static char seek_addr_buf[AR_SEEK_BUF_SIZE];


/* In write mode, we have to write a File Mark after the last block written, 
 * when the tape device is closed. Tape repositioning and reading in write
 * mode is allowed as long as no actual writing has been done. After writing
 * the File Mark, repositioning and reading are allowed again.
 */
static int  mode_access;        /* access mode: READ or WRITE */

static int qic02_get_resources(void);
static void qic02_release_resources(void);

/* This is a pointer to the actual kernel buffer where the interrupt routines
 * read from/write to. It is needed because the DMA channels 1 and 3 cannot
 * always access the user buffers. [The kernel buffer must reside in the
 * lower 16MBytes of system memory because of the DMA controller.] The user
 * must ensure that a large enough buffer is passed to the kernel, in order
 * to reduce tape repositioning wear and tear.
 */
static unsigned long buffaddr = 0;      /* physical address of buffer */

/* This translates minor numbers to the corresponding recording format: */
static const char *format_names[] = {
        "not set",      /* for dumb drives unable to handle format selection */
        "11",           /* extinct */
        "24",
        "120",
        "150",
        "300",          /* untested. */
        "600"           /* untested. */
};


/* `exception_list' is needed for exception status reporting.
 * Exceptions 1..14 are defined by QIC-02 rev F.
 * The drive status is matched sequentially to each entry,
 * ignoring irrelevant bits, until a match is found. If no
 * match is found, exception number 0 is used. (That should of
 * course never happen...) The original table was based on the
 * "Exception Status Summary" in QIC-02 rev F, but some changes
 * were required to make it work with real-world drives.
 *
 * Exception 2 (CNI) is changed to also cover status 0x00e0 (mask USL),
 * Exception 4 (EOM) is changed to also cover status 0x8288 (mask EOR),
 * Exception 11 (FIL) is changed to also cover status 0x0089 (mask EOM).
 * Exception 15 (EOR) is added for seek-to-end-of-data (catch EOR),
 * Exception 16 (BOM) is added for beginning-of-media (catch BOM).
 *
 * Had to swap EXC_NDRV and EXC_NCART to ensure that extended EXC_NCART
 * (because of the incorrect Wangtek status code) doesn't catch the
 * EXC_NDRV first.
 */
static struct exception_list_type {
        unsigned short mask, code;
        const char *msg;
        /* EXC_nr attribute should match with tpqic02.h */
} exception_list[] = {
        {0, 0,
                "Unknown exception status code",                /* extra: 0 */},
        {~(0), TP_ST0|TP_CNI|TP_USL|TP_WRP,
                "Drive not online"                              /* 1 */},
                /* Drive presence goes before cartridge presence. */
        {~(TP_WRP|TP_USL), TP_ST0|TP_CNI,
                /* My Wangtek 5150EQ sometimes reports a status code
                 * of 0x00e0, which is not a valid exception code, but
                 * I think it should be recognized as "NO CARTRIDGE".
                 */
                "Cartridge not in place"                        /* 2 */},
        {(unsigned short) ~(TP_ST1|TP_BOM), (TP_ST0|TP_WRP),
                "Write protected cartridge"                     /* 3 */},
        {(unsigned short) ~(TP_ST1|TP_EOR), (TP_ST0|TP_EOM),
                "End of media"                                  /* 4 */},
        {~TP_WRP, TP_ST0|TP_UDA| TP_ST1|TP_BOM,
                "Read or Write abort. Rewind tape."             /* 5 */},
        {~TP_WRP, TP_ST0|TP_UDA,
                "Read error. Bad block transferred."            /* 6 */},
        {~TP_WRP, TP_ST0|TP_UDA|TP_BNL,
                "Read error. Filler block transferred."         /* 7 */},
        {~TP_WRP, TP_ST0|TP_UDA|TP_BNL |TP_ST1|TP_NDT,
                "Read error. No data detected."                 /* 8 */},
        {~TP_WRP, TP_ST0|TP_EOM|TP_UDA|TP_BNL |TP_ST1|TP_NDT,
                "Read error. No data detected. EOM."            /* 9 */},
        {~(TP_WRP|TP_MBD|TP_PAR|TP_EOR), TP_ST0|TP_UDA|TP_BNL |TP_ST1|TP_NDT|TP_BOM,
                "Read error. No data detected. BOM."            /* 10 */},
        {~(TP_WRP|TP_EOM), TP_ST0|TP_FIL,
                /* Status 0x0089 (EOM & FM) is viewed as an FM,
                 * because it can only happen during a read.
                 * EOM is checked separately for an FM condition.
                 */
                "File mark detected"                            /* 11 */},
        {~(TP_ST0|TP_CNI|TP_USL|TP_WRP|TP_BOM), TP_ST1|TP_ILL,
                "Illegal command"                               /* 12 */},
        {~(TP_ST0|TP_CNI|TP_USL|TP_WRP|TP_BOM), TP_ST1|TP_POR,
                "Reset occurred"                                        /* 13 */},
        {~TP_WRP, TP_ST0|TP_FIL|TP_MBD,         /* NOTE: ST1 not set! */
                "Marginal block detected"                       /* 14 */},
        {~(TP_ST0|TP_WRP|TP_EOM|TP_UDA|TP_BNL|TP_FIL |TP_NDT), TP_ST1|TP_EOR,
                /********** Is the extra TP_NDT really needed Eddy? **********/
                "End of recorded media"                         /* extra: 15 */},
                /* 15 is returned when SEEKEOD completes successfully */
        {~(TP_WRP|TP_ST0), TP_ST1|TP_BOM,
                "Beginning of media"                            /* extra: 16 */}
};
#define NR_OF_EXC       (sizeof(exception_list)/sizeof(struct exception_list_type))

/* Compare expected struct size and actual struct size. This
 * is useful to catch programs compiled with old #includes.
 */
#define CHECK_IOC_SIZE(structure) \
        if (_IOC_SIZE(iocmd) != sizeof(struct structure)) { \
                tpqputs(TPQD_ALWAYS, "sizeof(struct " #structure \
                        ") does not match!"); \
                return -EFAULT; \
        } \

static void tpqputs(unsigned long flags, const char *s)
{
        if ((flags & TPQD_ALWAYS) || (flags & QIC02_TAPE_DEBUG))
                printk(TPQIC02_NAME ": %s\n", s);
} /* tpqputs */


/* Perform byte order swapping for a 16-bit word.
 *
 * [FIXME] This should probably be in include/asm/
 * ([FIXME] i486 can do this faster)
 */
static inline void byte_swap_w(volatile unsigned short * w)
{
        int t = *w;

        *w = (t>>8) | ((t & 0xff)<<8);
}



/* Init control register bits on interface card.
 * For Archive, interrupts must be enabled explicitly.
 * Wangtek interface card requires ONLINE to be set, Archive SC402/SC499R
 * cards keep it active all the time.
 */
static void ifc_init(void)
{
    if (QIC02_TAPE_IFC == WANGTEK) /* || (QIC02_TAPE_IFC == EVEREX) */
    {
        ctlbits = WT_CTL_ONLINE;        /* online */
        outb_p(ctlbits, QIC02_CTL_PORT);
    }
    else if (QIC02_TAPE_IFC == ARCHIVE)
    {
        ctlbits = 0;                    /* no interrupts yet */
        outb_p(ctlbits, QIC02_CTL_PORT);
        outb_p(0, AR_RESET_DMA_PORT);   /* dummy write to reset DMA */
    }
    else /* MOUNTAIN */
    {
        ctlbits = MTN_CTL_ONLINE;       /* online, and logic enabled */
        outb_p(ctlbits, QIC02_CTL_PORT);
    }
} /* ifc_init */


static void report_qic_exception(unsigned n)
{
    if (n >= NR_OF_EXC)
    {
        tpqputs(TPQD_ALWAYS, "Oops -- report_qic_exception");
        n = 0;
    }
    if (TPQDBG(SENSE_TEXT) || n==0)
    {
        printk(TPQIC02_NAME ": sense: %s\n", exception_list[n].msg);
    }
} /* report_qic_exception */


/* Try to map the drive-exception bits `s' to a predefined "exception number",
 * by comparing the significant exception bits for each entry in the
 * exception table (`exception_list[]').
 * It is assumed that s!=0.
 */
static int decode_qic_exception_nr(unsigned s)
{
    int i;

    for (i=1; i<NR_OF_EXC; i++)
    {
        if ((s & exception_list[i].mask)==exception_list[i].code)
        {
            return i;
        }
    }
    printk(TPQIC02_NAME ": decode_qic_exception_nr: exception(%x) not recognized\n", s);
    return 0;
} /* decode_qic_exception_nr */



/* Perform appropriate action for certain exceptions.
 * should return a value to indicate stop/continue (in case of bad blocks)
 */
static void handle_qic_exception(int exnr, int exbits)
{
    if (exnr==EXC_NCART)
    {
        /* Cartridge was changed. Redo sense().
         * EXC_NCART should be handled in open().
         * It is not permitted to remove the tape while
         * the tape driver has open files. 
         */
        need_rewind = YES;
        status_eof_detected = NO;
        status_eom_detected = NO;
    }
    else if (exnr==EXC_XFILLER)
    {
        tpqputs(TPQD_ALWAYS, "[Bad block -- filler data transferred.]");
    }
    else if (exnr==EXC_XBAD)
    {
        tpqputs(TPQD_ALWAYS, "[CRC failed!]");
    }
    else if (exnr==EXC_MARGINAL)
    {
        /* A marginal block behaves much like a FM.
         * User may continue reading, if desired.
         */
        tpqputs(TPQD_ALWAYS, "[Marginal block]");
        doing_read = NO;
    }
    else if (exnr==EXC_FM)
    {
        doing_read = NO;
    }
} /* handle_qic_exception */


static inline int is_exception(void)
{
    return (inb(QIC02_STAT_PORT) & QIC02_STAT_EXCEPTION) == 0;
} /* is_exception */


/* Reset the tape drive and controller.
 * When reset fails, it marks  the drive as dead and all
 * requests (except reset) are to be ignored (ENXIO).
 */
static int tape_reset(int verbose)
{
    ifc_init();                         /* reset interface card */

    /* assert reset */
    if (QIC02_TAPE_IFC == MOUNTAIN)
    {
        outb_p(ctlbits & ~MTN_QIC02_CTL_RESET_NOT, QIC02_CTL_PORT);
    }
    else /* WANGTEK, ARCHIVE */
    {
        outb_p(ctlbits | QIC02_CTL_RESET, QIC02_CTL_PORT);
    }
    
    /* Next, we need to wait >=25 usec. */
    udelay(30);

    /* after reset, we will be at BOT (modulo an automatic rewind) */
    status_eof_detected = NO;
    status_eom_detected = NO;
    status_cmd_pending = 0;
    need_rewind = YES;
    doing_read = doing_write = NO;
    ioctl_status.mt_fileno = ioctl_status.mt_blkno = 0;
    
    /* de-assert reset */
    if (QIC02_TAPE_IFC == MOUNTAIN)
    {
        outb_p(ctlbits | MTN_QIC02_CTL_RESET_NOT, QIC02_CTL_PORT);
    }
    else
    {
        outb_p(ctlbits & ~QIC02_CTL_RESET, QIC02_CTL_PORT);
    }
    
    /* KLUDGE FOR G++ BUG */
    { int stat = inb_p(QIC02_STAT_PORT);
        status_dead = ((stat & QIC02_STAT_RESETMASK) != QIC02_STAT_RESETVAL); }
    /* if successful, inb(STAT) returned RESETVAL */
    if (status_dead == YES)
    {
        printk(TPQIC02_NAME ": reset failed!\n");
    }
    else if (verbose)
    {
        printk(TPQIC02_NAME ": reset successful\n");
    }
    
    return (status_dead == YES)? TE_DEAD : TE_OK;
} /* tape_reset */



/* Notify tape drive of a new command. It only waits for the
 * command to be accepted, not for the actual command to complete.
 *
 * Before calling this routine, QIC02_CMD_PORT must have been loaded
 * with the command to be executed.
 * After this routine, the exception bit must be checked.
 * This routine is also used by rdstatus(), so in that case, any exception
 * must be ignored (`ignore_ex' flag).
 */
static int notify_cmd(char cmd, short ignore_ex)
{
        int i;

        outb_p(cmd, QIC02_CMD_PORT);    /* output the command */

        /* wait 1 usec before asserting /REQUEST */
        udelay(1);

        if ((!ignore_ex) && is_exception()) {
                tpqputs(TPQD_ALWAYS, "*** exception detected in notify_cmd");
                /** force a reset here **/
                if (tape_reset(1)==TE_DEAD)
                        return TE_DEAD;
                if (is_exception()) {
                        tpqputs(TPQD_ALWAYS, "exception persists after reset.");
                        tpqputs(TPQD_ALWAYS, " ^ exception ignored.");
                }
        }

        outb_p(ctlbits | QIC02_CTL_REQUEST, QIC02_CTL_PORT);  /* set request bit */
        i = TAPE_NOTIFY_TIMEOUT;
        /* The specs say this takes about 500 usec, but there is no upper limit!
         * If the drive were busy retensioning or something like that,
         * it could be *much* longer!
         */
        while ((inb_p(QIC02_STAT_PORT) & QIC02_STAT_READY) && (--i>0))
                /*skip*/;                         /* wait for ready */
        if (i==0) {
                tpqputs(TPQD_ALWAYS, "timed out waiting for ready in notify_cmd");
                status_dead = YES;
                return TE_TIM;
        }

        outb_p(ctlbits & ~QIC02_CTL_REQUEST, QIC02_CTL_PORT); /* reset request bit */
        i = TAPE_NOTIFY_TIMEOUT;
        /* according to the specs this one should never time-out */
        while (((inb_p(QIC02_STAT_PORT) & QIC02_STAT_READY) == 0) && (--i>0))
                /*skip*/;                         /* wait for not ready */
        if (i==0) {
                tpqputs(TPQD_ALWAYS, "timed out waiting for !ready in notify_cmd");
                status_dead = YES;
                return TE_TIM;
        }
        /* command accepted */
        return TE_OK;
} /* notify_cmd */



/* Wait for a command to complete, with timeout */
static int wait_for_ready(time_t timeout)
{
        int stat;
        time_t spin_t;

        /* Wait for ready or exception, without driving the loadavg up too much.
         * In most cases, the tape drive already has READY asserted,
         * so optimize for that case.
         *
         * First, busy wait a few usec:
         */
        spin_t = 50;
        while (((stat = inb_p(QIC02_STAT_PORT) & QIC02_STAT_MASK) == QIC02_STAT_MASK) && (--spin_t>0))
                /*SKIP*/;
        if ((stat & QIC02_STAT_READY) == 0)
                return TE_OK;                   /* covers 99.99% of all calls */

        /* Then use schedule() a few times */
        spin_t = 3;     /* max 0.03 sec busy waiting */
        if (spin_t > timeout)
                spin_t = timeout;
        timeout -= spin_t;
        spin_t += jiffies;

        while (((stat = inb_p(QIC02_STAT_PORT) & QIC02_STAT_MASK) == QIC02_STAT_MASK) && time_before(jiffies, spin_t))
                schedule();             /* don't waste all the CPU time */
        if ((stat & QIC02_STAT_READY) == 0)
                return TE_OK;

        /* If we reach this point, we probably need to wait much longer, or
         * an exception occurred. Either case is not very time-critical.
         * Check the status port only a few times every second.
         * A interval of less than 0.10 sec will not be noticed by the user,
         * more than 0.40 sec may give noticeable delays.
         */
        spin_t += timeout;
        TPQDEB({printk("wait_for_ready: additional timeout: %d\n", spin_t);})

                /* not ready and no exception && timeout not expired yet */
        while (((stat = inb_p(QIC02_STAT_PORT) & QIC02_STAT_MASK) == QIC02_STAT_MASK) && time_before(jiffies, spin_t)) {
                /* be `nice` to other processes on long operations... */
                current->state = TASK_INTERRUPTIBLE;
                /* nap 0.30 sec between checks, */
                /* but could be woken up earlier by signals... */
                schedule_timeout(3*HZ/10);
        }

        /* don't use jiffies for this test because it may have changed by now */
        if ((stat & QIC02_STAT_MASK) == QIC02_STAT_MASK) {
                tpqputs(TPQD_ALWAYS, "wait_for_ready() timed out");
                return TE_TIM;
        }

        if ((stat & QIC02_STAT_EXCEPTION) == 0) {
                tpqputs(TPQD_ALWAYS, "exception detected after waiting_for_ready");
                return TE_EX;
        } else {
                return TE_OK;
        }
} /* wait_for_ready */



/* Send some data to the drive */
static int send_qic02_data(char sb[], unsigned size, int ignore_ex)
{
        int i, stat;

        for (i=0; i<size; i++) {

                stat = wait_for_ready(TIM_S);
                if (stat != TE_OK)
                        return stat;

                stat = notify_cmd(sb[i], ignore_ex);
                if (stat != TE_OK)
                        return stat;
        }
        return TE_OK;
        
} /* send_qic02_data */


/* Send a QIC-02 command (`cmd') to the tape drive, with
 * a time-out (`timeout').
 * This one is also used by tp_sense(), so we must have
 * a flag to disable exception checking (`ignore_ex'). 
 *
 * On entry, the controller is supposed to be READY.
 */
static int send_qic02_cmd(int cmd, time_t timeout, int ignore_ex)
{
        int stat;

        stat = inb_p(QIC02_STAT_PORT);
        if ((stat & QIC02_STAT_EXCEPTION) == 0) {       /* if exception */
                tpqputs(TPQD_ALWAYS, "send_qic02_cmd: Exception!");
                return TE_EX;
        }
        if (stat & QIC02_STAT_READY) {                  /* if not ready */
                tpqputs(TPQD_ALWAYS, "send_qic02_cmd: not Ready!");
                return TE_ERR;
        }

        /* assert(ready & !exception) */

        /* Remember current command for later re-use with dma transfers.
         * (For reading/writing multiple blocks.)
         */
        status_cmd_pending = cmd;

        stat = notify_cmd(cmd, ignore_ex); /* tell drive new command was loaded, */
                                           /* inherit exception check. */
        if (TP_HAVE_SEEK && (cmd == AR_QCMDV_SEEK_BLK)) {
                /* This one needs to send 3 more bytes, MSB first */
                stat = send_qic02_data(seek_addr_buf, sizeof(seek_addr_buf), ignore_ex);
        }

        if (stat != TE_OK) {
                tpqputs(TPQD_ALWAYS, "send_qic02_cmd failed");
        }
        return stat;
} /* send_qic02_cmd */



/* Get drive status. Assume drive is ready or has exception set.
 * (or will be in <1000 usec.)
 * Extra parameters added because of 'Read Extended Status 3' command.
 */
static int rdstatus(char *stp, unsigned size, char qcmd)
{
        int     s, n;
        char    *q = stp;

        /* Try to busy-wait a few (700) usec, after that de-schedule.
         *
         * The problem is, if we don't de-schedule, performance will
         * drop to zero when the drive is not responding and if we
         * de-schedule immediately, we waste a lot of time because a
         * task switch is much longer than we usually have to wait here.
         */
        n = 1000;       /* 500 is not enough on a 486/33 */
        while ((n>0) && ((inb_p(QIC02_STAT_PORT) & QIC02_STAT_MASK) == QIC02_STAT_MASK))
                n--;  /* wait for ready or exception or timeout */
        if (n==0) {
                /* n (above) should be chosen such that on your machine
                 * you rarely ever see the message below, and it should
                 * be small enough to give reasonable response time.]
                 */
                tpqputs(TPQD_ALWAYS, "waiting looong in rdstatus() -- drive dead?");
                while ((inb_p(QIC02_STAT_PORT) & QIC02_STAT_MASK) == QIC02_STAT_MASK)
                        schedule();
                tpqputs(TPQD_ALWAYS, "finished waiting in rdstatus()");
        }

        (void) notify_cmd(qcmd, 1);                     /* send read status command */
        /* ignore return code -- should always be ok, STAT may contain 
         * exception flag from previous exception which we are trying to clear.
         */

        if (TP_DIAGS(current_tape_dev))
                printk(TPQIC02_NAME ": reading status bytes: ");

        for (q=stp; q<stp+size; q++)
        {
                do s = inb_p(QIC02_STAT_PORT);
                while ((s & QIC02_STAT_MASK) == QIC02_STAT_MASK);       /* wait for ready or exception */

                if ((s & QIC02_STAT_EXCEPTION) == 0) {          /* if exception */
                        tpqputs(TPQD_ALWAYS, "rdstatus: exception error");
                        ioctl_status.mt_erreg = 0;              /* dunno... */
                        return TE_NS;                           /* error, shouldn't happen... */
                }

                *q = inb_p(QIC02_DATA_PORT);                    /* read status byte */

                if (TP_DIAGS(current_tape_dev))
                        printk("[%1d]=0x%x  ", q-stp, (unsigned) (*q) & 0xff);

                outb_p(ctlbits | QIC02_CTL_REQUEST, QIC02_CTL_PORT);    /* set request */

                while ((inb_p(QIC02_STAT_PORT) & QIC02_STAT_READY) == 0);       /* wait for not ready */

                udelay(22);     /* delay >20 usec */

                outb_p(ctlbits & ~QIC02_CTL_REQUEST, QIC02_CTL_PORT);   /* un-set request */

        }

        /* Specs say we should wait for READY here.
         * My drive doesn't seem to need it here yet, but others do?
         */
        while (inb_p(QIC02_STAT_PORT) & QIC02_STAT_READY)
                /*skip*/;                         /* wait for ready */

        if (TP_DIAGS(current_tape_dev))
                printk("\n");

        return TE_OK;
} /* rdstatus */



/* Get standard status (6 bytes).
 * The `.dec' and `.urc' fields are in MSB-first byte-order,
 * so they have to be swapped first.
 */
static int get_status(volatile struct tpstatus *stp)
{
        int stat = rdstatus((char *) stp, TPSTATSIZE, QCMD_RD_STAT);
#if defined(i386) || defined(i486)
        byte_swap_w(&(stp->dec));
        byte_swap_w(&(stp->urc));
#else
        /* should probably swap status bytes #definition */
#endif
        return stat;
} /* get_status */


#if 0
/* This fails for my Wangtek drive */
/* get "Extended Status Register 3" (64 bytes)
 *
 * If the meaning of the returned bytes were known, the MT_TYPE
 * identifier could be used to decode them, since they are
 * "vendor unique". :-(
 */
static int get_ext_status3(void)
{
        char vus[64];   /* vendor unique status */
        int stat, i;

        tpqputs(TPQD_ALWAYS, "Attempting to read Extended Status 3...");
        stat = rdstatus(vus, sizeof(vus), QCMD_RD_STAT_X3);
        if (stat != TE_OK)
                return stat;

        tpqputs(TPQD_ALWAYS, "Returned status bytes:");
        for (i=0; i<sizeof(vus); i++) {
                if ( i % 8 == 0 )
                        printk("\n" TPQIC02_NAME ": %2d:");
                printk(" %2x", vus[i] & 0xff);
        }
        printk("\n");

        return TE_OK;
} /* get_ext_status3 */
#endif


/* Read drive status and set generic status too.
 * NOTE: Once we do a tp_sense(), read/write transfers are killed.
 */
static int tp_sense(int ignore)
{
        unsigned err = 0, exnr = 0, gs = 0;
        static void finish_rw(int cmd);

        if (TPQDBG(SENSE_TEXT))
                printk(TPQIC02_NAME ": tp_sense(ignore=0x%x) enter\n", ignore);

        /* sense() is not allowed during a read or write cycle */
        if (doing_write == YES)
                tpqputs(TPQD_ALWAYS, "Warning: File Mark inserted because of sense() request");
        /* The extra test is to avoid calling finish_rw during booting */
        if ((doing_read!=NO) || (doing_write!=NO))
                finish_rw(QCMD_RD_STAT);

        if (get_status(&tperror) != TE_OK) {
                tpqputs(TPQD_ALWAYS, "tp_sense: could not read tape drive status");
                return TE_ERR;
        }

        err = tperror.exs;      /* get exception status bits */
        if (err & (TP_ST0|TP_ST1))
                printk(TPQIC02_NAME ": tp_sense: status: %x, error count: %d, underruns: %d\n",
                        tperror.exs, tperror.dec, tperror.urc);
        else if ((tperror.dec!=0) || (tperror.urc!=0) || TPQDBG(SENSE_CNTS))
                printk(TPQIC02_NAME ": tp_sense: no hard errors, soft error count: %d, underruns: %d\n",
                        tperror.dec, tperror.urc);

        /* Set generic status. HP-UX defines these, but some extra would 
         * be useful. Problem is to remain compatible. [Do we want to be
         * compatible??]
         */
        if (err & TP_ST0) {
                if (err & TP_CNI)               /* no cartridge */
                        gs |= GMT_DR_OPEN(-1);
                if (status_dead == NO)
                        gs |= GMT_ONLINE(-1);   /* always online */
                if (err & TP_USL)               /* not online */
                        gs &= ~GMT_ONLINE(-1);
                if (err & TP_WRP)
                        gs |= GMT_WR_PROT(-1);
                if (err & TP_EOM) {             /* end of media */
                        gs |= GMT_EOT(-1);      /* not sure this is correct for writes */
                        status_eom_detected = YES;
                        /* I don't know whether drive always reports EOF at or before EOM. */
                        status_eof_detected = YES;
                }
                /** if (err & TP_UDA) "Unrecoverable data error" **/
                /** if (err & TP_BNL) "Bad block not located" **/
                if (err & TP_FIL) {
                        gs |= GMT_EOF(-1);
                        status_eof_detected = YES;
                }
        }
        if (err & TP_ST1) {
                /** if (err & TP_ILL) "Illegal command" **/
                /** if (err & TP_NDT) "No data detected" **/
                /** if (err & TP_MBD) "Marginal block detected" **/
                if (err & TP_BOM)
                        gs |= GMT_BOT(-1);      /* beginning of tape */
        }
        ioctl_status.mt_gstat = gs;
        ioctl_status.mt_dsreg = tperror.exs;    /* "drive status" */
        ioctl_status.mt_erreg = tperror.dec;    /* "sense key error" */

        if (err & (TP_ST0|TP_ST1)) {
                /* My Wangtek occasionally reports `status' 1212 which should be ignored. */
                exnr = decode_qic_exception_nr(err);
                handle_qic_exception(exnr, err);                /* update driver state wrt drive status */
                report_qic_exception(exnr);
        }
        err &= ~ignore;         /* mask unwanted errors -- not the correct way, use exception nrs?? */
        if (((err & TP_ST0) && (err & REPORT_ERR0)) ||
            ((err & TP_ST1) && (err & REPORT_ERR1)))
                return TE_ERR;
        return TE_OK;
} /* tp_sense */



/* Wait for a wind or rewind operation to finish or
 * to time-out. (May take very long).
 */
static int wait_for_rewind(time_t timeout)
{
        int stat;

        stat = inb(QIC02_STAT_PORT) & QIC02_STAT_MASK;
        if (TPQDBG(REWIND))
                printk(TPQIC02_NAME ": Waiting for (re-)wind to finish: stat=0x%x\n", stat);

        stat = wait_for_ready(timeout);

        if (stat != TE_OK) {
                        tpqputs(TPQD_ALWAYS, "(re-) winding failed\n");
        }
        return stat;
} /* wait_for_rewind */



/* Perform a full QIC02 command, and wait for completion,
 * check status when done. Complain about exceptions.
 *
 * This function should return an OS error code when
 * something goes wrong, 0 otherwise.
 */
static int ll_do_qic_cmd(int cmd, time_t timeout)
{
        int stat;

        if (status_dead == YES) {
                tpqputs(TPQD_ALWAYS, "Drive is dead. Do a `mt reset`.");
                return -ENXIO;                  /* User should do an MTRESET. */
        }

        stat = wait_for_ready(timeout);         /* wait for ready or exception */
        if (stat == TE_EX) {
                if (tp_sense(TP_WRP|TP_BOM|TP_EOM|TP_FIL)!=TE_OK)
                        return -EIO;
                /* else nothing to worry about, I hope */
                stat = TE_OK;
        }
        if (stat != TE_OK) {
                printk(TPQIC02_NAME ": ll_do_qic_cmd(%x, %ld) failed\n", cmd, (long) timeout);
                return -EIO;
        }


#if OBSOLETE
        /* wait for ready since it may not be active immediately after reading status */
        while ((inb_p(QIC02_STAT_PORT) & QIC02_STAT_READY) != 0);
#endif

        stat = send_qic02_cmd(cmd, timeout, 0); /* (checks for exceptions) */

        if (cmd==QCMD_RD_FM) {
                status_eof_detected = NO;
                ioctl_status.mt_fileno++;
                /* Should update block count as well, but can't.
                 * Can do a `read address' for some drives, when MTNOP is done.
                 */
        } else if (cmd==QCMD_WRT_FM) {
                status_eof_detected = NO;
                ioctl_status.mt_fileno++;
        } else if ((cmd==QCMD_REWIND) || (cmd==QCMD_ERASE) || (cmd==QCMD_RETEN)) {
                status_eof_detected = NO;
                status_eom_detected = NO;
                status_eot_detected = NO;
                need_rewind = NO;
                ioctl_status.mt_fileno = ioctl_status.mt_blkno = 0;
                extra_blocks_left = BLOCKS_BEYOND_EW;
                return_write_eof = NO;
                return_read_eof = NO;
                reported_read_eof = NO;
                reported_write_eof = NO;
        }
        /* sense() will set eof/eom as required */
        if (stat==TE_EX) {
                if (tp_sense(TP_WRP|TP_BOM|TP_EOM|TP_FIL)!=TE_OK) {
                        printk(TPQIC02_NAME ": Exception persist in ll_do_qic_cmd[1](%x, %ld)", cmd, (long) timeout);
                        status_dead = YES;
                        return -ENXIO;
                        /* if rdstatus fails too, we're in trouble */
                }
        }
        else if (stat!=TE_OK) {
                printk(TPQIC02_NAME ": ll_do_qic_cmd: send_qic02_cmd failed, stat = 0x%x\n", stat);
                return -EIO;    /*** -EIO is probably not always appropriate */
        }


        if (timeout == TIM_R)
                stat = wait_for_rewind(timeout);
        else
                stat = wait_for_ready(timeout);

        if (stat==TE_EX) {
                if (tp_sense((cmd==QCMD_SEEK_EOD ?              /*****************************/
                      TP_EOR|TP_NDT|TP_UDA|TP_BNL|TP_WRP|TP_BOM|TP_EOM|TP_FIL :
                      TP_WRP|TP_BOM|TP_EOM|TP_FIL))!=TE_OK) {
                        printk(TPQIC02_NAME ": Exception persist in ll_do_qic_cmd[2](%x, %ld)\n", cmd, (long) timeout);
                        if (cmd!=QCMD_RD_FM)
                                status_dead = YES;
                        return -ENXIO;
                        /* if rdstatus fails too, we're in trouble */
                }
        }
        else if (stat!=TE_OK) {
                printk(TPQIC02_NAME ": ll_do_qic_cmd %x: wait failed, stat == 0x%x\n", cmd, stat);
                return -EIO;
        }
        return 0;
} /* ll_do_qic_cmd */


/* 
 * Problem: What to do when the user cancels a read/write operation
 * in-progress?
 *
 * "Deactivating ONLINE during a READ also causes the"
 * "tape to be rewound to BOT." Ditto for WRITEs, except
 * a FM is written first. "The host may alternatively terminate
 * the READ/WRITE command by issuing a RFM/WFM command."
 *
 * For READs:
 * Neither option will leave the tape positioned where it was.
 * Another (better?) solution is to terminate the READ by two
 * subsequent sense() operations, the first to stop the current
 * READ cycle, the second to clear the `Illegal command' exception,
 * because the QIC-02 specs didn't anticipate this. This is
 * delayed until actually needed, so a tar listing can be aborted
 * by the user and continued later.
 * If anybody has a better solution, let me know! [Also, let me
 * know if your drive (mine is a Wangtek5150EQ) does not accept
 * this sequence for canceling the read-cycle.]
 *
 * For WRITEs it's simple: Just do a WRITE_FM, leaving the tape
 * positioned after the FM.
 */

static void terminate_read(int cmd)
{
        if (doing_read == YES) {
                doing_read = NO;
                if (cmd != QCMD_RD_FM) {
                        /* if the command is a RFM, there is no need to do this
                         * because a RFM will legally terminate the read-cycle.
                         */
                        tpqputs(TPQD_ALWAYS, "terminating pending read-cycle");

                        /* I'm not too sure about this part  -- hhb */
                        if (QIC02_TAPE_IFC == MOUNTAIN) {
                                /* Mountain reference says can terminate by de-asserting online */
                                ctlbits &= ~MTN_QIC02_CTL_ONLINE;
                        }
 
                        if (tp_sense(TP_FIL|TP_EOM|TP_WRP) != TE_OK) {
                                tpqputs(TPQD_ALWAYS, "finish_rw[read1]: ignore the 2 lines above");
                                if (is_exception()) {
                                        if (tp_sense(TP_ILL|TP_FIL|TP_EOM|TP_WRP) != TE_OK)
                                                tpqputs(TPQD_ALWAYS, "finish_rw[read2]: read cycle error");
                                }
                        }
                }
        }
} /* terminate_read */


static void terminate_write(int cmd)
{
        int stat;

        if (doing_write == YES) {
                doing_write = NO;
                /* Finish writing by appending a FileMark at the end. */
                if (cmd != QCMD_WRT_FM) {
                        /* finish off write cycle */
                        stat = ll_do_qic_cmd(QCMD_WRT_FM, TIM_M);
                        if (stat != TE_OK)
                                tpqputs(TPQD_ALWAYS, "Couldn't finish write cycle properly");
                        (void) tp_sense(0);
                }
                /* If there is an EOF token waiting to be returned to
                 * the (writing) application, discard it now.
                 * We could be at EOT, so don't reset return_write_eof.
                 */
                reported_write_eof=YES;
        }
} /* terminate_write */


/* terminate read or write cycle because of command `cmd' */
static void finish_rw(int cmd)
{
        if (wait_for_ready(TIM_S) != TE_OK) {
                tpqputs(TPQD_ALWAYS, "error: drive not ready in finish_rw() !");
                return;
        }
        terminate_read(cmd);
        terminate_write(cmd);
} /* finish_rw */


/* Perform a QIC command through ll_do_qic_cmd().
 * If necessary, rewind the tape first.
 * Return an OS error code if something goes wrong, 0 if all is well.
 */
static int do_qic_cmd(int cmd, time_t timeout)
{
        int stat;


        finish_rw(cmd);

        if (need_rewind) {
                tpqputs(TPQD_REWIND, "Rewinding tape...");
                stat = ll_do_qic_cmd(QCMD_REWIND, TIM_R);
                if (stat != 0) {
                        printk(TPQIC02_NAME ": rewind failed in do_qic_cmd(). stat=0x%2x", stat);
                        return stat;
                }
                need_rewind = NO;
                if (cmd==QCMD_REWIND)   /* don't wind beyond BOT ;-) */
                        return 0;
        }

        return ll_do_qic_cmd(cmd, timeout);
} /* do_qic_cmd */


/* Not all ioctls are supported for all drives. Some rely on
 * optional QIC-02 commands. Check tpqic02.h for configuration.
 * Some of these commands may require ONLINE to be active.
 */
static int do_ioctl_cmd(int cmd)
{
        int stat;

        /* It is not permitted to read or wind the tape after bytes have
         * been written. It is not permitted to write the tape while in
         * read mode.
         * We try to be kind and allow reading again after writing a FM...
         */

        switch (cmd) {
                case MTRESET:
                        /* reset verbose */
                        return (tape_reset(1)==TE_OK)? 0 : -EIO;

                case MTFSF:
                        tpqputs(TPQD_IOCTLS, "MTFSF forward searching filemark");
                        if ((mode_access==WRITE) && status_bytes_wr)
                                return -EACCES;
                        return do_qic_cmd(QCMD_RD_FM, TIM_F);

                case MTBSF:
                        if (TP_HAVE_BSF) {
                                tpqputs(TPQD_IOCTLS, "MTBSF backward searching filemark -- optional command");
                                if ((mode_access==WRITE) && status_bytes_wr)
                                        return -EACCES;
                                stat = do_qic_cmd(QCMD_RD_FM_BCK, TIM_F);
                        } else {
                                stat = -ENXIO;
                        }
                        status_eom_detected = status_eof_detected = NO;
                        return stat;

                case MTFSR:
                        if (TP_HAVE_FSR) { /* This is an optional QIC-02 command */
                                tpqputs(TPQD_IOCTLS, "MTFSR forward space record");
                                if ((mode_access==WRITE) && status_bytes_wr)
                                        return -EACCES;
                                stat = do_qic_cmd(QCMD_SPACE_FWD, TIM_F);
                        } else {
                                /**** fake it by doing a read data block command? ******/
                                tpqputs(TPQD_IOCTLS, "MTFSR not supported");
                                stat = -ENXIO;
                        }
                        return stat;

                case MTBSR:
                        if (TP_HAVE_BSR) { /* This is an optional QIC-02 command */
                                /* we need this for appending files with GNU tar!! */
                                tpqputs(TPQD_IOCTLS, "MTFSR backward space record");
                                if ((mode_access==WRITE) && status_bytes_wr)
                                        return -EACCES;
                                stat = do_qic_cmd(QCMD_SPACE_BCK, TIM_F);
                        } else {
                                tpqputs(TPQD_IOCTLS, "MTBSR not supported");
                                stat = -ENXIO;
                        }
                        status_eom_detected = status_eof_detected = NO;
                        return stat;

                case MTWEOF:
                        tpqputs(TPQD_IOCTLS, "MTWEOF write eof mark");
                        /* Plain GNU mt(1) 2.2 uses read-only mode for writing FM. :-( */
                        if (mode_access==READ)
                                return -EACCES;

                        /* allow tape movement after writing FM */
                        status_bytes_rd = status_bytes_wr;      /* Kludge-O-Matic */
                        status_bytes_wr = NO;
                        return do_qic_cmd(QCMD_WRT_FM, TIM_M);
                        /* not sure what to do with status_bytes when WFM should fail */

                case MTREW:
                        tpqputs(TPQD_IOCTLS, "MTREW rewinding tape");
                        if ((mode_access==WRITE) && status_bytes_wr)
                                return -EACCES;
                        status_eom_detected = status_eof_detected = NO;
                        return do_qic_cmd(QCMD_REWIND, TIM_R);

                case MTOFFL:
                        tpqputs(TPQD_IOCTLS, "MTOFFL rewinding & going offline");
                        /* Doing a drive select will clear (unlock) the current drive.
                         * But that requires support for multiple drives and locking.
                         */
                        if ((mode_access==WRITE) && status_bytes_wr)
                                return -EACCES;
                        status_eom_detected = status_eof_detected = NO;
                        /**** do rewind depending on minor bits??? ***/
                        stat = do_qic_cmd(QCMD_REWIND, TIM_R);
                        return stat;

                case MTNOP:
                        tpqputs(TPQD_IOCTLS, "MTNOP setting status only");
                        /********** should do `read position' for drives that support it **********/
                        return (tp_sense(-1)==TE_OK)? 0 : -EIO; /**** check return codes ****/

                case MTRETEN:
                        tpqputs(TPQD_IOCTLS, "MTRETEN retension tape");
                        if ((mode_access==WRITE) && status_bytes_wr)
                                return -EACCES;
                        status_eom_detected = status_eof_detected = NO;
                        return do_qic_cmd(QCMD_RETEN, TIM_R);

                case MTBSFM:
                        /* Think think is like MTBSF, except that
                         * we shouldn't skip the FM. Tricky.
                         * Maybe use RD_FM_BCK, then do a SPACE_FWD?
                         */
                        tpqputs(TPQD_IOCTLS, "MTBSFM not supported");
                        if ((mode_access==WRITE) && status_bytes_wr)
                                return -EACCES;
                        return -ENXIO;

                case MTFSFM:
                        /* I think this is like MTFSF, except that
                         * we shouldn't skip the FM. Tricky.
                         * Maybe use QCMD_RD_DATA until we get a TP_FIL exception?
                         * But then the FM will have been skipped...
                         * Maybe use RD_FM, then RD_FM_BCK, but not all
                         * drives will support that!
                         */
                        tpqputs(TPQD_IOCTLS, "MTFSFM not supported");
                        if ((mode_access==WRITE) && status_bytes_wr)
                                return -EACCES;
                        return -ENXIO;

                case MTEOM:
                        /* This should leave the tape ready for appending
                         * another file to the end, such that it would append
                         * after the last FM on tape.
                         */
                        tpqputs(TPQD_IOCTLS, "MTEOM search for End Of recorded Media");
                        if ((mode_access==WRITE) && status_bytes_wr)
                                return -EACCES;
                        if (TP_HAVE_EOD) {
                                /* Use faster seeking when possible.
                                 * This requires the absence of data beyond the EOM.
                                 * It seems that my drive does not always perform the
                                 * SEEK_EOD correctly, unless it is preceded by a
                                 * rewind command.
                                 */
# if 0
                                status_eom_detected = status_eof_detected = NO;
# endif
                                stat = do_qic_cmd(QCMD_REWIND, TIM_R);
                                if (stat)
                                        return stat;
                                stat = do_qic_cmd(QCMD_SEEK_EOD, TIM_F);
                                /* After a successful seek, TP_EOR should be returned */
                        } else {
                                /* else just seek until the drive returns exception "No Data" */
                                stat = 0;
                                while ((stat==0) && (!status_eom_detected)) {
                                        stat = do_qic_cmd(QCMD_RD_FM, TIM_F); /***** should use MTFSFM here???? ******/
                                }
                                if (tperror.exs & TP_NDT)
                                        return 0;
                        }
                        return stat;

                case MTERASE:
                        tpqputs(TPQD_IOCTLS, "MTERASE -- ERASE TAPE !");
                        if  ((tperror.exs & TP_ST0) && (tperror.exs & TP_WRP)) {
                                tpqputs(TPQD_ALWAYS, "Cartridge is write-protected.");
                                return -EACCES;
                        } else {
                                time_t t = jiffies;

                                /* Plain GNU mt(1) 2.2 erases a tape in O_RDONLY. :-( */
                                if (mode_access==READ) 
                                        return -EACCES;

                                /* give user a few seconds to pull out tape */
                                while (jiffies - t < 4*HZ)
                                        schedule();
                        }

                        /* don't bother writing filemark first */
                        status_eom_detected = status_eof_detected = NO;
                        return do_qic_cmd(QCMD_ERASE, TIM_R);

                case MTRAS1:
                        if (TP_HAVE_RAS1) {
                                tpqputs(TPQD_IOCTLS, "MTRAS1: non-destructive self test");
                                stat = do_qic_cmd(QCMD_SELF_TST1, TIM_R);
                                if (stat != 0) {
                                        tpqputs(TPQD_ALWAYS, "RAS1 failed");
                                        return stat;
                                }
                                return (tp_sense(0)==TE_OK)? 0 : -EIO; /* get_ext_status3(); */
                        }
                        tpqputs(TPQD_IOCTLS, "RAS1 not supported");
                        return -ENXIO;

                case MTRAS2:
                        if (TP_HAVE_RAS2) {
                                tpqputs(TPQD_IOCTLS, "MTRAS2: destructive self test");
                                stat = do_qic_cmd(QCMD_SELF_TST2, TIM_R);
                                if (stat != 0) {
                                        tpqputs(TPQD_ALWAYS, "RAS2 failed");
                                        return stat;
                                }
                                return (tp_sense(0)==TE_OK)? 0 : -EIO; /* get_ext_status3(); */
                        }
                        tpqputs(TPQD_IOCTLS, "RAS2 not supported");
                        return -ENXIO;

                case MTSEEK:
                        if (TP_HAVE_SEEK && (QIC02_TAPE_IFC==ARCHIVE)) {
                                tpqputs(TPQD_IOCTLS, "MTSEEK seeking block");
                                if ((mode_access==WRITE) && status_bytes_wr)
                                        return -EACCES;
                                /* NOTE: address (24 bits) is in seek_addr_buf[] */
                                return do_qic_cmd(AR_QCMDV_SEEK_BLK, TIM_F);
                        }
                        else
                                return -ENOTTY;

                default:
                        return -ENOTTY;
        }
} /* do_ioctl_cmd */


/* dma_transfer(): This routine is called for every 512 bytes to be read
 * from/written to the tape controller. Speed is important here!
 * (There must be enough time left for the hd controller!)
 * When other devices use DMA they must ensure they use un-interruptible
 * double byte accesses to the DMA controller. Floppy.c is ok.
 * Must have interrupts disabled when this function is invoked,
 * otherwise, the double-byte transfers to the DMA controller will not
 * be atomic. That could lead to nasty problems when they are interrupted
 * by other DMA interrupt-routines.
 *
 * This routine merely does the least possible to keep
 * the transfers going:
 *      - set the DMA count register for the next 512 bytes
 *      - adjust the DMA address and page registers
 *      - adjust the timeout
 *      - tell the tape controller to start transferring
 * We assume the dma address and mode are, and remain, valid.
 */ 
static inline void dma_transfer(void)
{
        unsigned long flags;

        if (QIC02_TAPE_IFC == WANGTEK) /* or EVEREX */
                outb_p(WT_CTL_ONLINE, QIC02_CTL_PORT);  /* back to normal */
        else if (QIC02_TAPE_IFC == ARCHIVE)
                outb_p(0, AR_RESET_DMA_PORT);
        else /* QIC02_TAPE_IFC == MOUNTAIN */
                outb_p(ctlbits, QIC02_CTL_PORT);


        flags=claim_dma_lock();
        clear_dma_ff(QIC02_TAPE_DMA);
        set_dma_mode(QIC02_TAPE_DMA, dma_mode);
        set_dma_addr(QIC02_TAPE_DMA, buffaddr+dma_bytes_done);  /* full address */
        set_dma_count(QIC02_TAPE_DMA, TAPE_BLKSIZE);

        /* start tape DMA controller */
        if (QIC02_TAPE_IFC == WANGTEK) /* or EVEREX */
                outb_p(WT_CTL_DMA | WT_CTL_ONLINE, QIC02_CTL_PORT); /* trigger DMA transfer */

        else if (QIC02_TAPE_IFC == ARCHIVE) {
                outb_p(AR_CTL_IEN | AR_CTL_DNIEN, QIC02_CTL_PORT);  /* enable interrupts again */
                outb_p(0, AR_START_DMA_PORT);                     /* start DMA transfer */
                /* In dma_end() AR_RESET_DMA_PORT is written too. */

        } else /* QIC02_TAPE_IFC == MOUNTAIN */ {
                inb(MTN_R_DESELECT_DMA_PORT);
                outb_p(ctlbits | (MTN_CTL_EXC_IEN | MTN_CTL_DNIEN), QIC02_CTL_PORT);
                outb_p(0, MTN_W_SELECT_DMA_PORT);        /* start DMA transfer */
                if (dma_mode == DMA_MODE_WRITE)
                        outb_p(0, MTN_W_DMA_WRITE_PORT); /* start DMA transfer */
        }

        /* start computer DMA controller */
        enable_dma(QIC02_TAPE_DMA);

        release_dma_lock(flags);

        /* block transfer should start now, jumping to the 
         * interrupt routine when done or an exception was detected.
         */
} /* dma_transfer */


/* start_dma() sets a DMA transfer up between the tape controller and
 * the kernel qic02_tape_buf buffer.
 * Normally bytes_todo==dma_bytes_done at the end of a DMA transfer. If not,
 * a filemark was read, or an attempt to write beyond the End Of Tape 
 * was made. [Or some other bad thing happened.]
 * Must do a sense() before returning error.
 */
static int start_dma(short mode, unsigned long bytes_todo)
/* assume 'bytes_todo'>0 */
{
        int stat;
        unsigned long flags;
        
        tpqputs(TPQD_DEBUG, "start_dma() enter");
        TPQDEB({printk(TPQIC02_NAME ": doing_read==%d, doing_write==%d\n", doing_read, doing_write);})

        dma_bytes_done = 0;
        dma_bytes_todo = bytes_todo;
        status_error = NO;
        /* dma_mode!=0 indicates that the dma controller is in use */
        dma_mode = (mode == WRITE)? DMA_MODE_WRITE : DMA_MODE_READ;     

        /* Only give READ/WRITE DATA command to tape drive if we haven't
         * done that already. Otherwise the drive will rewind to the beginning
         * of the current file on tape. Any QIC command given other than
         * R/W FM will break the read/write transfer cycle.
         * do_qic_cmd() will terminate doing_{read,write}
         */
        if ((doing_read == NO) && (doing_write == NO)) {
                /* First, we have to clear the status -- maybe remove TP_FIL???
                 */

#if 0
                /* Next dummy get status is to make sure CNI is valid,
                   since we're only just starting a read/write it doesn't
                   matter some exceptions are cleared by reading the status;
                   we're only interested in CNI and WRP. -Eddy */
                get_status(&tperror);
#else
                /* TP_CNI should now be handled in open(). -Hennus */
#endif

                stat = tp_sense(((mode == WRITE)? 0 : TP_WRP) | TP_BOM | TP_FIL);
                if (stat != TE_OK)
                        return stat;

#if OBSOLETE
                /************* not needed iff rd_status() would wait for ready!!!!!! **********/
                if (wait_for_ready(TIM_S) != TE_OK) {   /*** not sure this is needed ***/
                        tpqputs(TPQD_ALWAYS, "wait_for_ready failed in start_dma");
                        return -EIO;
                }
#endif

                if (QIC02_TAPE_IFC == MOUNTAIN) {
                        /* Set control bits to select ONLINE during command */
                        ctlbits |= MTN_QIC02_CTL_ONLINE;
                }

                /* Tell the controller the data direction */

                /* r/w, timeout medium, check exceptions, sets status_cmd_pending. */
                stat = send_qic02_cmd((mode == WRITE)? QCMD_WRT_DATA : QCMD_RD_DATA, TIM_M, 0);
                if (stat!=TE_OK) {
                        printk(TPQIC02_NAME ": start_dma: init %s failed\n",
                                (mode == WRITE)? "write" : "read");
                        (void) tp_sense(0);
                        return stat;
                }

                /* Do this last, because sense() will clear the doing_{read,write}
                 * flags, causing trouble next time around.
                 */
                if (wait_for_ready(TIM_M) != TE_OK)
                        return -EIO;
                switch (mode) {
                        case READ:
                                doing_read = YES;
                                break;
                        case WRITE:
                                doing_write = YES;
                                break;
                        default:
                                printk(TPQIC02_NAME ": requested unknown mode %d\n", mode);
                                panic(TPQIC02_NAME ": invalid mode in start_dma()");
                }

        } else if (is_exception()) {
                /* This is for Archive drives, to handle reads with 0 bytes
                 * left for the last read request.
                 *
                 * ******** this also affects EOF/EOT handling! ************
                 */
                tpqputs(TPQD_ALWAYS, "detected exception in start_dma() while transfer in progress");
                status_error = YES;
                return TE_END;
        }


        status_expect_int = YES;

        /* This assumes tape is already positioned, but these
         * semi-'intelligent' drives are unpredictable...
         */
        TIMERON(TIM_M*2);

        /* initiate first data block read from/write to the tape controller */

        save_flags(flags);
        cli();
        dma_transfer();
        restore_flags(flags);

        TPQPUTS("start_dma() end");
        return TE_OK;
} /* start_dma */


/* This cleans up after the dma transfer has completed
 * (or failed). If an exception occurred, a sense()
 * must be done. If the exception was caused by a FM,
 * sense() will set `status_eof_detected' and
 * `status_eom_detected', as required.
 */
static void end_dma(unsigned long * bytes_done)
{
        int stat = TE_OK;
        unsigned long flags;

        TIMEROFF;

        TPQPUTS("end_dma() enter");

        flags=claim_dma_lock();
        
        disable_dma(QIC02_TAPE_DMA);
        clear_dma_ff(QIC02_TAPE_DMA);
        
        release_dma_lock(flags);

        if (QIC02_TAPE_IFC == WANGTEK) /* or EVEREX */
                outb_p(WT_CTL_ONLINE, QIC02_CTL_PORT);  /* back to normal */
        else if (QIC02_TAPE_IFC == ARCHIVE)
                outb_p(0, AR_RESET_DMA_PORT);
        else /* QIC02_TAPE_IFC == MOUNTAIN */ {
                /* Clear control bits, de-select ONLINE during tp_sense */
                ctlbits &= ~MTN_QIC02_CTL_ONLINE;
        }

        stat = wait_for_ready(TIM_M);
        if (status_error || (stat!=TE_OK)) {
                tpqputs(TPQD_DMAX, "DMA transfer exception");
                stat = tp_sense((dma_mode==READ)? TP_WRP : 0);
                /* no return here -- got to clean up first! */
        } else /* if (QIC02_TAPE_IFC == MOUNTAIN) */ {
                outb_p(ctlbits, QIC02_CTL_PORT);
        }

        if (QIC02_TAPE_IFC == MOUNTAIN)
                inb(MTN_R_DESELECT_DMA_PORT);

        /* take the tape controller offline */

        /* finish off DMA stuff */


        dma_mode = 0;
        /* Note: The drive is left on-line, ready for the next
         * data transfer.
         * If the next command to the drive does not continue
         * the pending cycle, it must do 2 sense()s first.
         */

        *bytes_done = dma_bytes_done;
        status_expect_int = NO;
        ioctl_status.mt_blkno += (dma_bytes_done / TAPE_BLKSIZE);

        TPQPUTS("end_dma() exit");
        /*** could return stat here ***/
} /* end_dma */

/*********** Below are the (public) OS-interface procedures ***********/


/* qic02_tape_times_out() is called when a DMA transfer doesn't complete
 * quickly enough. Usually this means there is something seriously wrong
 * with the hardware/software, but it could just be that the controller
 * has decided to do a long rewind, just when I didn't expect it.
 * Just try again.
 */
static void qic02_tape_times_out(void)
{
        printk("time-out in %s driver\n", TPQIC02_NAME);
        if ((status_cmd_pending>0) || dma_mode) {
                /* takes tooo long, shut it down */
                status_dead = YES;
                status_cmd_pending = 0;
                status_timer_on = NO;
                status_expect_int = NO;
                status_error = YES;
                if (dma_mode) {
                        dma_mode = 0;   /* signal end to read/write routine */
                        wake_up(&qic02_tape_transfer);
                }
        }
} /* qic02_tape_times_out */

/*
 * Interrupt handling:
 *
 * 1) Interrupt is generated iff at the end of 
 *    a 512-DMA-block transfer.
 * 2) EXCEPTION is not raised unless something 
 *    is wrong or EOT/FM is detected.
 * 3) FM EXCEPTION is set *after* the last byte has
 *    been transferred by DMA. By the time the interrupt
 *    is handled, the EXCEPTION may already be set.
 *
 * So,
 * 1) On EXCEPTION, assume data has been transferred, so
 *    continue as usual, but set a flag to indicate the
 *    exception was detected.
 *    Do a sense status when the flag is found set.
 * 2) Do not attempt to continue a transfer after an exception.
 *    [??? What about marginal blocks???????]
 */


/* qic02_tape_interrupt() is called when the tape controller completes 
 * a DMA transfer.
 * We are not allowed to sleep here! 
 *
 * Check if the transfer was successful, check if we need to transfer
 * more. If the buffer contains enough data/is empty enough, signal the
 * read/write() thread to copy to/from user space.
 * When we are finished, set flags to indicate end, disable timer.
 * NOTE: This *must* be fast! 
 */
static void qic02_tape_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
        int stat, r, i;
        unsigned long flags;

        TIMEROFF;

        if (status_expect_int) {
#ifdef WANT_EXTRA_FULL_DEBUGGING
                if (TP_DIAGS(current_tape_dev))
                        printk("@");
#endif
                stat = inb(QIC02_STAT_PORT);    /* Knock, knock */
                if (QIC02_TAPE_IFC == ARCHIVE) {        /* "Who's there?" */
                        if (((stat & (AR_STAT_DMADONE)) == 0) &&
                              ((stat & (QIC02_STAT_EXCEPTION)) != 0)) {
                                TIMERCONT;
                                return;                 /* "Linux with IRQ sharing" */
                        }
                }

                if ((stat & QIC02_STAT_EXCEPTION) == 0) {       /* exception occurred */
                        /* Possible causes for an exception during a transfer:
                         *      - during a write-cycle: end of tape (EW) hole detected.
                         *      - during a read-cycle: filemark or EOD detected.
                         *      - something went wrong
                         * So don't continue with the next block.
                         */
                        tpqputs(TPQD_ALWAYS, "isr: exception on tape controller");
                        printk("      status %02x\n", stat);
                        status_error = TE_EX;

                        dma_bytes_done += TAPE_BLKSIZE;

                        dma_mode = 0;   /* wake up rw() */
                        status_expect_int = NO;
                        wake_up(&qic02_tape_transfer);
                        return;
                }
                /* return if tape controller not ready, or
                 * if dma channel hasn't finished last byte yet.
                 */
                r = 0;

            /* Skip next ready check for Archive controller because
             * it may be busy reading ahead. Weird. --hhb
             */
                if (QIC02_TAPE_IFC == WANGTEK)  /* I think this is a drive-dependency, not IFC -- hhb */
                        if (stat & QIC02_STAT_READY) {          /* not ready */
                                tpqputs(TPQD_ALWAYS, "isr: ? Tape controller not ready");
                                r = 1;
                        }

                flags=claim_dma_lock();
                
                if ( (i = get_dma_residue(QIC02_TAPE_DMA)) != 0 ) {
                        printk(TPQIC02_NAME ": dma_residue == %x !!!\n", i);
                        r = 1;  /* big trouble, but can't do much about it... */
                }
                
                release_dma_lock(flags);

                if (r) 
                        return;

                /* finish DMA cycle */

                /* no errors detected, continue */
                dma_bytes_done += TAPE_BLKSIZE;
                if (dma_bytes_done >= dma_bytes_todo) {
                        /* finished! Wakeup rw() */
                        dma_mode = 0;
                        status_expect_int = NO;
                        TPQPUTS("isr: dma_bytes_done");
                        wake_up(&qic02_tape_transfer);
                } else {
                        /* start next transfer, account for track-switching time */
                        timer_table[QIC02_TAPE_TIMER].expires = jiffies + 6*HZ;
                        dma_transfer();
                }
        } else {
                printk(TPQIC02_NAME ": Unexpected interrupt, stat == %x\n",
                       inb(QIC02_STAT_PORT));
        }
} /* qic02_tape_interrupt */


static long long qic02_tape_lseek(struct file * file, long long offset, int origin)
{
        return -EINVAL; /* not supported */
} /* qic02_tape_lseek */


/* read/write routines:
 * This code copies between a kernel buffer and a user buffer. The 
 * actual data transfer is done using DMA and interrupts. Time-outs
 * are also used.
 *
 * When a filemark is read, we return '0 bytes read' and continue with the
 * next file after that.
 * When EOM is read, we return '0 bytes read' twice.
 * When the EOT marker is detected on writes, '0 bytes read' should be
 * returned twice. If user program does a MTNOP after that, 2 additional
 * blocks may be written.       ------- FIXME: Implement this correctly  *************************************************
 *
 * Only read/writes in multiples of 512 bytes are accepted.
 * When no bytes are available, we sleep() until they are. The controller will
 * generate an interrupt, and we (should) get a wake_up() call.
 *
 * Simple buffering is used. User program should ensure that a large enough
 * buffer is used. Usually the drive does some buffering as well (something
 * like 4k or so).
 *
 * Scott S. Bertilson suggested to continue filling the user buffer, rather
 * than waste time on a context switch, when the kernel buffer fills up.
 */

/*
 * Problem: tar(1) doesn't always read the entire file. Sometimes the entire file
 * has been read, but the EOF token is never returned to tar(1), simply because
 * tar(1) knows it has already read all of the data it needs. So we must use
 * open/release to reset the `reported_read_eof' flag. If we don't, the next read
 * request would return the EOF flag for the previous file.
 */

static ssize_t qic02_tape_read(struct file * filp, char * buf, size_t count, loff_t *ppos)
{
    int err;
    kdev_t dev = filp->f_dentry->d_inode->i_rdev;
    unsigned short flags = filp->f_flags;
    unsigned long bytes_todo, bytes_done, total_bytes_done = 0;
    int stat;

    if (status_zombie==YES)
    {
        tpqputs(TPQD_ALWAYS, "configs not set");                
        return -ENXIO;
    }

    if (TP_DIAGS(current_tape_dev))
      /* can't print a ``long long'' (for filp->f_pos), so chop it */
      printk(TPQIC02_NAME ": request READ, minor=%x, buf=%p, count=%lx"
                          ", pos=%lx, flags=%x\n",
             MINOR(dev), buf, (long) count,
             (unsigned long) filp->f_pos, flags);
    
    if (count % TAPE_BLKSIZE)   /* Only allow mod 512 bytes at a time. */
    {
        tpqputs(TPQD_BLKSZ, "Wrong block size");
        return -EINVAL;
    }

    /* Just assume everything is ok. Controller will scream if not. */

    if (status_bytes_wr)        /* Once written, no more reads, 'till after WFM. */
    {
        return -EACCES;
    }
    
    /* This is rather ugly because it has to implement a finite state
     * machine in order to handle the EOF situations properly.
     */
    while ((signed)count>=0)
    {
        bytes_done = 0;
        /* see how much fits in the kernel buffer */
        bytes_todo = TPQBUF_SIZE;
        if (bytes_todo>count)
        {
            bytes_todo = count;
        }
        
        /* Must ensure that user program sees exactly one EOF token (==0) */
        if (return_read_eof==YES)
        {
            if (TPQDBG(DEBUG))
            {
                printk("read: return_read_eof==%d, reported_read_eof==%d, total_bytes_done==%lu\n", return_read_eof, reported_read_eof, total_bytes_done);
            }
            
            if (reported_read_eof==NO)
            {
                /* have not yet returned EOF to user program */
                if (total_bytes_done>0)
                {
                    return total_bytes_done; /* next time return EOF */
                }
                else
                {
                    reported_read_eof = YES; /* move on next time */
                    return 0;            /* return EOF */
                }                               
            }
            else
            {
                /* Application program has already received EOF
                 * (above), now continue with next file on tape,
                 * if possible.
                 * When the FM is reached, EXCEPTION is set,
                 * causing a sense(). Subsequent read/writes will
                 * continue after the FM.
                 */
                /*********** ?????????? this should check for (EOD|NDT), not EOM, 'cause we can read past EW: ************/
                if (status_eom_detected)
                {
                    /* If EOM, nothing left to read, so keep returning EOFs.
                     *** should probably set some flag to avoid clearing
                     *** status_eom_detected through ioctls or something
                     */
                    return 0;
                }
                else
                {
                    /* just eof, there may be more files ahead... */
                    return_read_eof = NO;
                    reported_read_eof = NO;
                    status_eof_detected = NO; /* reset this too */
                    /*fall through*/
                }
            }
        }
        
        /*****************************/
        if (bytes_todo==0)
        {
            return total_bytes_done;
        }
        
        if (bytes_todo>0)
        {
            /* start reading data */
            if (is_exception()) /****************************************/
            {
                tpqputs(TPQD_DMAX, "is_exception() before start_dma()!");
            }
            
/******************************************************************
 ***** if start_dma() fails because the head is positioned 0 bytes
 ***** before the FM, (causing EXCEPTION to be set) return_read_eof should
 ***** be set to YES, and we should return total_bytes_done, rather than -ENXIO.
 ***** The app should recognize this as an EOF condition.
 ***************************************************************************/
            stat = start_dma(READ, bytes_todo);
            if (stat == TE_OK)
            {
                /* Wait for transfer to complete, interrupt should wake us */
                while (dma_mode != 0)
                {
                    sleep_on(&qic02_tape_transfer);
                }
                if (status_error)
                {
                    return_read_eof = YES;
                }
                
            }
            else if (stat != TE_END)
            {
                /* should do sense() on error here */
#if 0
                return -ENXIO;
#else
                printk("Trouble: stat==%02x\n", stat);
                return_read_eof = YES;
                /*************** check EOF/EOT handling!!!!!! **/
#endif
            }
            end_dma(&bytes_done);
            if (bytes_done>bytes_todo)
            {
                tpqputs(TPQD_ALWAYS, "read: Oops, read more bytes than requested");
                return -EIO;
            }
            /* copy buffer to user-space in one go */
            if (bytes_done>0)
            {
                err = copy_to_user( (void *) buf, (void *) bus_to_virt(buffaddr), bytes_done);
                if (err)
                {
                    return -EFAULT;
                }
            }
#if 1
            /* Checks Ton's patch below */
            if ((return_read_eof == NO) && (status_eof_detected == YES))
            {
                printk(TPQIC02_NAME ": read(): return_read_eof=%d, status_eof_detected=YES. return_read_eof:=YES\n", return_read_eof);
            }
#endif
            if ((bytes_todo != bytes_done) || (status_eof_detected == YES))
            {
                /* EOF or EOM detected. return EOF next time. */
                return_read_eof = YES;
            }
            
        } /* else: ignore read request for 0 bytes */

        if (bytes_done>0)
        {
            status_bytes_rd = YES;
            buf += bytes_done;
            *ppos += bytes_done;
            total_bytes_done += bytes_done;
            count -= bytes_done;
        }
    }
    tpqputs(TPQD_ALWAYS, "read request for <0 bytes");
    return -EINVAL;
} /* qic02_tape_read */



/* The drive detects near-EOT by means of the holes in the tape.
 * When the holes are detected, there is some space left. The drive
 * reports this as a TP_EOM exception. After clearing the exception,
 * the drive should accept two extra blocks.
 *
 * It seems there are some archiver programs that would like to use the
 * extra space for writing a continuation marker. The driver should return
 * end-of-file to the user program on writes, when the holes are detected.
 * If the user-program wants to use the extra space, it should use the
 * MTNOP ioctl() to get the generic status register and may then continue
 * writing (max 1kB).   ----------- doesn't work yet...............
 *
 * EOF behaviour on writes:
 * If there is enough room, write all of the data.
 * If there is insufficient room, write as much as will fit and
 * return the amount written. If the requested amount differs from the
 * written amount, the application program should recognize that as the
 * end of file. Subsequent writes will return -ENOSPC.
 * Unless the minor bits specify a rewind-on-close, the tape will not
 * be rewound when it is full. The user-program should do that, if desired.
 * If the driver were to do that automatically, a user-program could be 
 * confused about the EOT/BOT condition after re-opening the tape device.
 *
 * Multiple volume support: Tar closes the tape device before prompting for
 * the next tape. The user may then insert a new tape and tar will open the
 * tape device again. The driver will detect an exception status in (No Cartridge)
 * and force a rewind. After that tar may continue writing.
 */
static ssize_t qic02_tape_write( struct file * filp,  const char * buf, 
                size_t count, loff_t *ppos)
{
    int err;
    kdev_t dev = filp->f_dentry->d_inode->i_rdev;
    unsigned short flags = filp->f_flags;
    unsigned long bytes_todo, bytes_done, total_bytes_done = 0;
    
    if (status_zombie==YES)
    {
        tpqputs(TPQD_ALWAYS, "configs not set");                
        return -ENXIO;
    }

    if (TP_DIAGS(current_tape_dev))
    {
        /* can't print a ``long long'' (for filp->f_pos), so chop it */
        printk(TPQIC02_NAME ": request WRITE, minor=%x, buf=%p"
                            ", count=%lx, pos=%lx, flags=%x\n",
               MINOR(dev), buf,
               (long) count, (unsigned long) filp->f_pos, flags);
    }
    
    if (count % TAPE_BLKSIZE)   /* only allow mod 512 bytes at a time */
    {
        tpqputs(TPQD_BLKSZ, "Wrong block size");
        return -EINVAL;
    }

    if (mode_access==READ)
    {
        tpqputs(TPQD_ALWAYS, "Not in write mode");
        return -EACCES;
    }

    /* open() does a sense() and we can assume the tape isn't changed
     * between open() and release(), so the tperror.exs bits will still
     * be valid.
     */
    if ((tperror.exs & TP_ST0) && (tperror.exs & TP_WRP))
    {
        tpqputs(TPQD_ALWAYS, "Cartridge is write-protected.");
        return -EACCES; /* don't even try when write protected */
    }
      
    if (doing_read == YES)
    {
        terminate_read(0);
    }
    
    while ((signed)count>=0)
    {
        /* see how much fits in the kernel buffer */
        bytes_done = 0;
        bytes_todo = TPQBUF_SIZE;
        if (bytes_todo>count)
        {
            bytes_todo = count;
        }
        
        if (return_write_eof == YES)
        {
            /* return_write_eof should be reset on reverse tape movements. */
            
            if (reported_write_eof==NO)
            {
                if (bytes_todo>0)
                {
                    tpqputs(TPQD_ALWAYS, "partial write");
                    /* partial write signals EOF to user program */
                }
                reported_write_eof = YES;
                return total_bytes_done;
            }
            else
            {
                return -ENOSPC;          /* return error */
            }   
        }
        
        /* Quit when done. */
        if (bytes_todo==0)
        {
            return total_bytes_done;
        }
        
        /* copy from user to DMA buffer and initiate transfer. */
        if (bytes_todo>0)
        {
            err = copy_from_user( (void *) bus_to_virt(buffaddr), (const void *) buf, bytes_todo);
            if (err)
            {
                return -EFAULT;
            }

/****************** similar problem with read() at FM could happen here at EOT.
 ******************/

/***** if at EOT, 0 bytes can be written. start_dma() will
 ***** fail and write() will return ENXIO error
 *****/
            if (start_dma(WRITE, bytes_todo) != TE_OK)
            {
                tpqputs(TPQD_ALWAYS, "write: start_dma() failed");
                /* should do sense() on error here */
                return -ENXIO;  /*********** FIXTHIS **************/
            }

            /* Wait for write to complete, interrupt should wake us. */
            while ((status_error == 0) && (dma_mode != 0))
            {
                sleep_on(&qic02_tape_transfer);
            }

            end_dma(&bytes_done);
            if (bytes_done>bytes_todo)
            {
                tpqputs(TPQD_ALWAYS, "write: Oops, wrote more bytes than requested");
                return -EIO;
            }
            /* If the dma-transfer was aborted because of an exception,
             * status_error will have been set in the interrupt handler.
             * Then end_dma() will do a sense().
             * If the exception was EXC_EOM, the EW-hole was encountered
             * and two more blocks could be written. For the time being we'll
             * just consider this to be the EOT.
             * Otherwise, something Bad happened, such as the maximum number
             * of block-rewrites was exceeded. [e.g. A very bad spot on tape was
             * encountered. Normally short dropouts are compensated for by
             * rewriting the block in error, up to 16 times. I'm not sure
             * QIC-24 drives can do this.]
             */
            if (status_error)
            {
                if (status_eom_detected == YES)
                {
                    tpqputs(TPQD_ALWAYS, "write: EW detected");
                    return_write_eof = YES;
                }
                else
                {
                    /* probably EXC_RWA */
                    tpqputs(TPQD_ALWAYS, "write: dma: error in writing");
                    return -EIO;
                }
            }
            if (bytes_todo != bytes_done)
            {
                /* EOF or EOM detected. return EOT next time. */
                return_write_eof = YES;
            }
        }
        /* else: ignore write request for 0 bytes. */
        
        if (bytes_done>0)
        {
            status_bytes_wr = YES;
            buf += bytes_done;
            *ppos += bytes_done;
            total_bytes_done += bytes_done;
            count -= bytes_done;
        }
    }
    
    tpqputs(TPQD_ALWAYS, "write request for <0 bytes");
    if (TPQDBG(DEBUG))
    {
        printk(TPQIC02_NAME ": status_bytes_wr %x, buf %p"
                            ", total_bytes_done %lx, count %lx\n",
               status_bytes_wr, buf, total_bytes_done, (long) count);
    }
    return -EINVAL;
} /* qic02_tape_write */



/* qic02_tape_open()
 * We allow the device to be opened, even if it is marked 'dead' because
 * we want to be able to reset the tape device without rebooting.
 * Only one open tape file at a time, except when minor=255.
 * Minor 255 is only allowed for resetting and always returns <0.
 * 
 * The density command is only allowed when TP_BOM is set. Thus, remember
 * the most recently used minor bits. When they are different from the
 * remembered values, rewind the tape and set the required density.
 * Don't rewind if the minor bits specify density 0.
 */

static int qic02_tape_open(struct inode * inode, struct file * filp)
{
    static int qic02_tape_open_no_use_count(struct inode *, struct file *);
    int open_error;

    open_error = qic02_tape_open_no_use_count(inode, filp);
    if (!open_error)
    {
        MOD_INC_USE_COUNT;
    }
    return open_error;
}

static int qic02_tape_open_no_use_count(struct inode * inode, struct file * filp)
{
    kdev_t dev = inode->i_rdev;
    unsigned short flags = filp->f_flags;
    unsigned short dens = 0;
    int s;


    if (TP_DIAGS(dev))
    {
        printk("qic02_tape_open: dev=%s, flags=%x     ",
               kdevname(dev), flags);
    }

    if (MINOR(dev)==255)        /* special case for resetting */
    {
        if (suser())
        {
            return (tape_reset(1)==TE_OK) ? -EAGAIN : -ENXIO;
        }
        else
        {
            return -EPERM;
        }
    }
    
    if (status_dead==YES)
    {
        /* Allow `mt reset' ioctl() even when already open()ed. */
        return 0;
    }
    
        /* Only one at a time from here on... */
    if (file_count(filp)>1)     /* filp->f_count==1 for the first open() */
    {
        return -EBUSY;
    }

    if (status_zombie==YES)
    {
        /* no irq/dma/port stuff allocated yet, no reset done
         * yet, so return until MTSETCONFIG has been done.
         */
        return 0;
    }
    
    status_bytes_rd = NO;
    status_bytes_wr = NO;
    
    return_read_eof = NO;       /********????????????????*****/
    return_write_eof = (status_eot_detected)? YES : NO;

    /* Clear this in case user app close()d before reading EOF token */
    status_eof_detected = NO;

    reported_read_eof = NO;
    reported_write_eof = NO;


    switch (flags & O_ACCMODE)
    {
     case O_RDONLY:
        mode_access = READ;
        break;
     case O_WRONLY:     /* Fallthru... Strictly speaking this is not correct... */
     case O_RDWR:       /* Reads are allowed as long as nothing is written */
        mode_access = WRITE;
        break;
    }
    
    /* This is to avoid tape-changed problems (TP_CNI exception).
     *
     * Since removing the cartridge will not raise an exception,
     * we always do a tp_sense() to make sure we have the proper
     * CNI status, the 2150L may need an additional sense.... - Eddy
     */
    s = tp_sense(TP_WRP|TP_EOM|TP_BOM|TP_CNI|TP_EOR);
    
    if (s == TE_OK)
    {
        /* Try to clear cartridge-changed status for Archive-2150L */
        if ((tperror.exs & TP_ST0) && (tperror.exs & TP_CNI))
        {
            s = tp_sense(TP_WRP|TP_EOM|TP_BOM|TP_CNI|TP_EOR);
        }
    }
    
    if (s != TE_OK)
    {
        tpqputs(TPQD_ALWAYS, "open: sense() failed");
        return -EIO;
    }

    /* exception bits should be up-to-date now, so check for
     * tape presence and exit if absent.
     * Even `mt stat' will fail without a tape.
     */
    if ((tperror.exs & TP_ST0) && (tperror.exs & TP_CNI))
    {
        tpqputs(TPQD_ALWAYS, "No tape present.");
        return -EIO;
    }

    /* At this point we can assume that a tape is present and
     * that it will remain present until release() is called.
     */

    /* not allowed to do QCMD_DENS_* unless tape is rewound */
    if ((TP_DENS(dev)!=0) && (TP_DENS(current_tape_dev) != TP_DENS(dev)))
    {
        /* force rewind if minor bits have changed,
         * i.e. user wants to use tape in different format.
         * [assuming single drive operation]
         */
        if (TP_HAVE_DENS)
        {
            tpqputs(TPQD_REWIND, "Density minor bits have changed. Forcing rewind.");
            need_rewind = YES;
        }
    }
    else
    {
        /* density bits still the same, but TP_DIAGS bit 
         * may have changed.
         */
        current_tape_dev = dev;
    }
    
    if (need_rewind == YES)  /***************** CHECK THIS!!!!!!!! **********/
    {
        s = do_qic_cmd(QCMD_REWIND, TIM_R);
        if (s != 0)
        {
            tpqputs(TPQD_ALWAYS, "open: rewind failed");
            return -EIO;
        }
    }


/* Note: After a reset command, the controller will rewind the tape
 *       just before performing any tape movement operation! ************ SO SET need_rewind flag!!!!!
 */ 
    if (status_dead==YES)
    {
        tpqputs(TPQD_ALWAYS, "open: tape dead, attempting reset");
        if (tape_reset(1)!=TE_OK)
        {
            return -ENXIO;
        }
        else
        {
            status_dead = NO;
            if (tp_sense(~(TP_ST1|TP_ILL)) != TE_OK)
            {
                tpqputs(TPQD_ALWAYS, "open: tp_sense() failed\n");
                status_dead = YES;      /* try reset next time */
                return -EIO;
            }
        }
    }
    
    /* things should be ok, once we get here */
    

    /* set density: only allowed when TP_BOM status bit is set,
     * so we must have done a rewind by now. If not, just skip over.
     * Only give set density command when minor bits have changed.
     */
    if (TP_DENS(current_tape_dev) == TP_DENS(dev) )
    {
        return 0;
    }
    
    current_tape_dev = dev;
    need_rewind = NO;
    if (TP_HAVE_DENS)
    {
        dens = TP_DENS(dev);
    }
    
    if (dens < sizeof(format_names)/sizeof(char *))
    {
        printk(TPQIC02_NAME ": format: %s%s\n", (dens!=0)? "QIC-" : "", format_names[dens]);
    }
    else
    {
        tpqputs(TPQD_REWIND, "Wait for retensioning...");
    }
    
    switch (TP_DENS(dev))
    {
     case 0: /* Minor 0 is for drives without set-density support */
        s = 0;
        break;
     case 1:
        s = do_qic_cmd(QCMD_DENS_11, TIM_S);
        break;
     case 2:
        s = do_qic_cmd(QCMD_DENS_24, TIM_S);
        break;
     case 3:
        s = do_qic_cmd(QCMD_DENS_120, TIM_S);
        break;
     case 4:
        s = do_qic_cmd(QCMD_DENS_150, TIM_S);
        break;
     case 5:
        s = do_qic_cmd(QCMD_DENS_300, TIM_S);
        break;
     case 6:
        s = do_qic_cmd(QCMD_DENS_600, TIM_S);
        break;
     default:  /* otherwise do a retension before anything else */
        s = do_qic_cmd(QCMD_RETEN, TIM_R);
    }
    if (s != 0)
    {
        status_dead = YES;      /* force reset */
        current_tape_dev = 0; /* earlier 0xff80 */
        return -EIO;
    }
    
    return 0;
} /* qic02_tape_open */


static int qic02_tape_release(struct inode * inode, struct file * filp)
{
    kdev_t dev = inode->i_rdev;

    if (TP_DIAGS(dev))
    {
        printk("qic02_tape_release: dev=%s\n",  kdevname(dev));
    }
    
    if (status_zombie==NO)              /* don't rewind in zombie mode */
    {
        /* Terminate any pending write cycle. Terminating the read-cycle
         * is delayed until it is required to do so for a new command.
         */
        terminate_write(-1);
        
        if (status_dead==YES)
        {
            tpqputs(TPQD_ALWAYS, "release: device dead!?");
        }
        
        /* Rewind only if minor number requires it AND 
         * read/writes have been done. ************* IS THIS CORRECT??????????
         */
        if ((TP_REWCLOSE(dev)) && (status_bytes_rd | status_bytes_wr))
        {
            tpqputs(TPQD_REWIND, "release: Doing rewind...");
            (void) do_qic_cmd(QCMD_REWIND, TIM_R);
        }
    }
#ifdef MODULE
    MOD_DEC_USE_COUNT;
#endif
    return 0;
} /* qic02_tape_release */


#ifdef CONFIG_QIC02_DYNCONF
/* Set masks etc. based on the interface card type. */
static int update_ifc_masks(int ifc)
{
    QIC02_TAPE_IFC = ifc;

    if ((QIC02_TAPE_IFC == WANGTEK) || (QIC02_TAPE_IFC == EVEREX))
    {
        QIC02_STAT_PORT = QIC02_TAPE_PORT;
        QIC02_CTL_PORT = QIC02_TAPE_PORT;
        QIC02_CMD_PORT = QIC02_TAPE_PORT+1;
        QIC02_DATA_PORT = QIC02_TAPE_PORT+1;
        QIC02_STAT_READY = WT_QIC02_STAT_READY;
        QIC02_STAT_EXCEPTION = WT_QIC02_STAT_EXCEPTION;
        QIC02_STAT_MASK = WT_QIC02_STAT_MASK;
        
        QIC02_STAT_RESETMASK = WT_QIC02_STAT_RESETMASK;
        QIC02_STAT_RESETVAL = WT_QIC02_STAT_RESETVAL;
        
        QIC02_CTL_RESET = WT_QIC02_CTL_RESET;
        QIC02_CTL_REQUEST = WT_QIC02_CTL_REQUEST;
 
        if (QIC02_TAPE_DMA == 3)
        {
            WT_CTL_DMA = WT_CTL_DMA3;
        }
        else if (QIC02_TAPE_DMA == 1)
        {
            WT_CTL_DMA = WT_CTL_DMA1;
        }
        else
        {
            tpqputs(TPQD_ALWAYS, "Unsupported or incorrect DMA channel");
            return -EIO;
        } 

        if (QIC02_TAPE_IFC == EVEREX)
        {
            /* Everex is a special case for Wangtek (actually
             * it's the other way 'round, but I saw Wangtek first)
             */
            if (QIC02_TAPE_DMA==3)
            {
                WT_CTL_DMA = WT_CTL_DMA1;
            }
            
            /* Fixup the kernel copy of the IFC type to that
             * we don't have to distinguish between Wangtek and
             * and Everex at runtime.
             */
            QIC02_TAPE_IFC = WANGTEK;
        }
    }
    else if (QIC02_TAPE_IFC == ARCHIVE)
    {
        QIC02_STAT_PORT = QIC02_TAPE_PORT+1;
        QIC02_CTL_PORT = QIC02_TAPE_PORT+1;
        QIC02_CMD_PORT = QIC02_TAPE_PORT;
        QIC02_DATA_PORT = QIC02_TAPE_PORT;
        QIC02_STAT_READY = AR_QIC02_STAT_READY;
        QIC02_STAT_EXCEPTION  = AR_QIC02_STAT_EXCEPTION;
        QIC02_STAT_MASK = AR_QIC02_STAT_MASK;
        
        QIC02_STAT_RESETMASK = AR_QIC02_STAT_RESETMASK;
        QIC02_STAT_RESETVAL = AR_QIC02_STAT_RESETVAL;
        
        QIC02_CTL_RESET = AR_QIC02_CTL_RESET;
        QIC02_CTL_REQUEST = AR_QIC02_CTL_REQUEST;
        
        if (QIC02_TAPE_DMA > 3)
        {
            tpqputs(TPQD_ALWAYS, "Unsupported or incorrect DMA channel");
            return -EIO;
        } 
    }
    else if (QIC02_TAPE_IFC == MOUNTAIN)
    {
        QIC02_STAT_PORT = QIC02_TAPE_PORT+1;
        QIC02_CTL_PORT = QIC02_TAPE_PORT+1;
        QIC02_CMD_PORT = QIC02_TAPE_PORT;
        QIC02_DATA_PORT = QIC02_TAPE_PORT;
        
        QIC02_STAT_READY = MTN_QIC02_STAT_READY;
        QIC02_STAT_EXCEPTION  = MTN_QIC02_STAT_EXCEPTION;
        QIC02_STAT_MASK = MTN_QIC02_STAT_MASK;
        
        QIC02_STAT_RESETMASK = MTN_QIC02_STAT_RESETMASK;
        QIC02_STAT_RESETVAL = MTN_QIC02_STAT_RESETVAL;
        
        QIC02_CTL_RESET = MTN_QIC02_CTL_RESET;
        QIC02_CTL_REQUEST = MTN_QIC02_CTL_REQUEST;
        
        if (QIC02_TAPE_DMA > 3)
        {
            tpqputs(TPQD_ALWAYS, "Unsupported or incorrect DMA channel");
            return -EIO;
        } 
    }
    else
    {
        tpqputs(TPQD_ALWAYS, "Invalid interface type");
        return -ENXIO;
    }
    return qic02_get_resources();
} /* update_ifc_masks */
#endif


/* ioctl allows user programs to rewind the tape and stuff like that */
static int qic02_tape_ioctl(struct inode * inode, struct file * filp, 
                     unsigned int iocmd, unsigned long ioarg)
{
    int error;
    int dev_maj = MAJOR(inode->i_rdev);
    int c;
    struct mtop operation;
    unsigned char blk_addr[6];
    struct mtpos ioctl_tell;
    

    if (TP_DIAGS(current_tape_dev))
    {
        printk(TPQIC02_NAME ": ioctl(%4x, %4x, %4lx)\n", dev_maj, iocmd, ioarg);
    }
    
    if (!inode || !ioarg)
    {
        return -EINVAL;
    }
    
    /* check iocmd first */

    if (dev_maj != QIC02_TAPE_MAJOR)
    {
        printk(TPQIC02_NAME ": Oops! Wrong device?\n");
        /* A panic() would be appropriate here */
        return -ENODEV;
    }

    c = _IOC_NR(iocmd);

#ifdef CONFIG_QIC02_DYNCONF
    if (c == _IOC_NR(MTIOCGETCONFIG))
    {
        CHECK_IOC_SIZE(mtconfiginfo);

        if (copy_to_user((char *) ioarg, (char *) &qic02_tape_dynconf, sizeof(qic02_tape_dynconf)))
        {
            return -EFAULT;
        }
        return 0;

    }
    else if (c == _IOC_NR(MTIOCSETCONFIG))
    {
        /* One should always do a MTIOCGETCONFIG first, then update
         * user-settings, then write back with MTIOCSETCONFIG.
         * The qic02conf program should re-open() the device before actual
         * use, to make sure everything is initialized.
         */
        
        CHECK_IOC_SIZE(mtconfiginfo);
        
        if (!suser())
        {
            return -EPERM;
        }
        
        if ((doing_read!=NO) || (doing_write!=NO))
        {
            return -EBUSY;
        }
        
        if (status_zombie==NO)
        {
            qic02_release_resources();  /* and go zombie */
        }
        
        /* copy struct from user space to kernel space */
        if (copy_from_user((char *) &qic02_tape_dynconf, (char *) ioarg, sizeof(qic02_tape_dynconf)))
        {
            return -EFAULT;
        }
        return update_ifc_masks(qic02_tape_dynconf.ifc_type);
    }
    if (status_zombie==YES)
    {
        tpqputs(TPQD_ALWAYS, "Configs not set");
        return -ENXIO;
    }
#endif
    if (c == _IOC_NR(MTIOCTOP))
    {
        CHECK_IOC_SIZE(mtop);

        /* copy mtop struct from user space to kernel space */
        if (copy_from_user((char *) &operation, (char *) ioarg, sizeof(operation)))
        {
            return -EFAULT;
        }

        /* ---note: mt_count is signed, negative seeks must be
         * ---      translated to seeks in opposite direction!
         * (only needed for Sun-programs, I think.)
         */
        /* ---note: MTFSF with count 0 should position the
         * ---      tape at the beginning of the current file.
         */

        if (TP_DIAGS(current_tape_dev))
        {
            printk("OP op=%4x, count=%4x\n", operation.mt_op, operation.mt_count);
        }
        
        if (operation.mt_count < 0)
        {
            tpqputs(TPQD_ALWAYS, "Warning: negative mt_count ignored");
        }
        
        ioctl_status.mt_resid = operation.mt_count;
        if (operation.mt_op == MTSEEK)
        {
            if (!TP_HAVE_SEEK)
            {
                return -ENOTTY;
            }
            
            seek_addr_buf[0] = (operation.mt_count>>16)&0xff;
            seek_addr_buf[1] = (operation.mt_count>>8)&0xff;
            seek_addr_buf[2] = (operation.mt_count)&0xff;
            if (operation.mt_count>>24)
            {
                return -EINVAL;
            }
            if ((error = do_ioctl_cmd(operation.mt_op)) != 0)
            {
                return error;
            }
            
            ioctl_status.mt_resid = 0;
        }
        else
        {
            while (operation.mt_count > 0)
            {
                operation.mt_count--;
                if ((error = do_ioctl_cmd(operation.mt_op)) != 0)
                {
                    return error;
                }
                
                ioctl_status.mt_resid = operation.mt_count;
            }
        }
        return 0;
        
    }
    else if (c == _IOC_NR(MTIOCGET))
    {
        if (TP_DIAGS(current_tape_dev))
        {
            printk("GET ");
        }
        
        CHECK_IOC_SIZE(mtget);

        /* It appears (gmt(1)) that it is normal behaviour to
         * first set the status with MTNOP, and then to read
         * it out with MTIOCGET
         */

        /* copy results to user space */
        if (copy_to_user((char *) ioarg, (char *) &ioctl_status, sizeof(ioctl_status)))
        {
            return -EFAULT;
        }       
        return 0;
    }
    else if (TP_HAVE_TELL && (c == _IOC_NR(MTIOCPOS)))
    {
        if (TP_DIAGS(current_tape_dev))
        {
            printk("POS ");
        }
        
        CHECK_IOC_SIZE(mtpos);
        
        tpqputs(TPQD_IOCTLS, "MTTELL reading block address");
        if ((doing_read==YES) || (doing_write==YES))
        {
            finish_rw(AR_QCMDV_TELL_BLK);
        }
        
        c = rdstatus((char *) blk_addr, sizeof(blk_addr), AR_QCMDV_TELL_BLK);
        if (c!=TE_OK)
        {
            return -EIO;
        }
        
        ioctl_tell.mt_blkno = (blk_addr[3] << 16) | (blk_addr[4] << 8) | blk_addr[5];

        /* copy results to user space */
        if (copy_to_user((char *) ioarg, (char *) &ioctl_tell, sizeof(ioctl_tell)))
        {
            return -EFAULT;
        }
        return 0;

    }
    else
    {
        return -ENOTTY; /* Other cmds not supported. */
    }
} /* qic02_tape_ioctl */



/* These are (most) of the interface functions: */
static struct file_operations qic02_tape_fops = {
        qic02_tape_lseek,               /* not allowed */
        qic02_tape_read,                /* read */
        qic02_tape_write,               /* write */
        NULL,                           /* readdir not allowed */
        NULL,                           /* poll ??? */
        qic02_tape_ioctl,               /* ioctl */
        NULL,                           /* mmap not allowed */
        qic02_tape_open,                /* open */
        NULL,                           /* flush */
        qic02_tape_release,             /* release */
        NULL,                           /* fsync */
        NULL,                           /* fasync */
        NULL,                           /* check_media_change */
        NULL                            /* revalidate */
};


/* Why is this not is one place? */
/* Pure 2^n version of get_order */
static inline int __get_order(unsigned long size)
{
    int order;

    size = (size-1) >> (PAGE_SHIFT-1);
    order = -1;
    do
    {
        size >>= 1;
        order++;
    } while (size);
    return order;
}


static void qic02_release_resources(void)
{
    free_irq(QIC02_TAPE_IRQ, NULL);
    free_dma(QIC02_TAPE_DMA);
    release_region(QIC02_TAPE_PORT, QIC02_TAPE_PORT_RANGE);
    if (buffaddr)
    {
        free_pages(buffaddr, __get_order(TPQBUF_SIZE));
    }
    buffaddr = 0; /* Better to cause a panic than overwite someone else */
    status_zombie = YES;
} /* qic02_release_resources */


static int qic02_get_resources(void)
{
    /* First perform some checks. If one of them fails,
     * the tape driver will not be registered to the system.
     */
    if (QIC02_TAPE_IRQ>16)
    {
        tpqputs(TPQD_ALWAYS, "Bogus interrupt number.");
        return -ENXIO;
    }

    /* for DYNCONF, allocating IO, DMA and IRQ should not be done until 
     * the config parameters have been set using MTSETCONFIG.
     */

    if (check_region(QIC02_TAPE_PORT, QIC02_TAPE_PORT_RANGE))
    {
        printk(TPQIC02_NAME ": IO space at 0x%x [%d ports] already reserved\n",
               QIC02_TAPE_PORT, QIC02_TAPE_PORT_RANGE);
        return -ENXIO;
    }

    /* get IRQ */
    if (request_irq(QIC02_TAPE_IRQ, qic02_tape_interrupt, SA_INTERRUPT, "QIC-02", NULL))
    {
        printk(TPQIC02_NAME ": can't allocate IRQ%d for QIC-02 tape\n",
               QIC02_TAPE_IRQ);
        return -EBUSY;
    }

    /* After IRQ, allocate DMA channel */
    if (request_dma(QIC02_TAPE_DMA,"QIC-02"))
    {
        printk(TPQIC02_NAME ": can't allocate DMA%d for QIC-02 tape\n",
               QIC02_TAPE_DMA);
        free_irq(QIC02_TAPE_IRQ, NULL);
        return -EBUSY;
    }

    /* Grab the IO region. We already made sure it's available. */
    request_region(QIC02_TAPE_PORT, QIC02_TAPE_PORT_RANGE, TPQIC02_NAME);
    
    /* Setup the page-address for the dma transfer. */

    /*** TODO: does _get_dma_pages() really return the physical address?? ****/
    buffaddr = __get_dma_pages(GFP_KERNEL,__get_order(TPQBUF_SIZE));
    
    if (!buffaddr)
    {
        qic02_release_resources();
        return -EBUSY; /* Not ideal, EAGAIN perhaps? */
    }
    
    memset( (void*) buffaddr, 0, TPQBUF_SIZE );
    
    printk(TPQIC02_NAME ": Settings: IRQ %d, DMA %d, IO 0x%x, IFC %s\n",
           QIC02_TAPE_IRQ, QIC02_TAPE_DMA,
           ((QIC02_TAPE_IFC==ARCHIVE) || (QIC02_TAPE_IFC==MOUNTAIN))?
           QIC02_CMD_PORT : QIC02_STAT_PORT,
           (QIC02_TAPE_IFC==MOUNTAIN)? "Mountain" :
           ((QIC02_TAPE_IFC==ARCHIVE)? "Archive" : "Wangtek"));
    
    if (tape_reset(0)!=TE_OK || tp_sense(TP_WRP|TP_POR|TP_CNI)!=TE_OK)
    {
        /* No drive detected, so vanish */
        tpqputs(TPQD_ALWAYS, "No drive detected -- releasing IO/IRQ/DMA.");
        status_dead = YES;
        qic02_release_resources();
        return -EIO;
    }

    /* All should be ok now */
    status_zombie = NO;
    return 0;
} /* qic02_get_resources */

int __init qic02_tape_init(void)
{
    if (TPSTATSIZE != 6)
    {
        printk(TPQIC02_NAME ": internal error: tpstatus struct incorrect!\n");
        return -ENODEV;
    }
    if ((TPQBUF_SIZE<512) || (TPQBUF_SIZE>=0x10000))
    {
        printk(TPQIC02_NAME ": internal error: DMA buffer size out of range\n");
        return -ENODEV;
    }

    current_tape_dev = MKDEV(QIC02_TAPE_MAJOR, 0);

#ifndef CONFIG_QIC02_DYNCONF
    printk(TPQIC02_NAME ": IRQ %d, DMA %d, IO 0x%x, IFC %s, %s, %s\n",
           QIC02_TAPE_IRQ, QIC02_TAPE_DMA,
# if QIC02_TAPE_IFC == WANGTEK
           QIC02_STAT_PORT, "Wangtek",
# elif QIC02_TAPE_IFC == ARCHIVE
           QIC02_CMD_PORT, "Archive",
# elif QIC02_TAPE_IFC == MOUNTAIN
           QIC02_CMD_PORT, "Mountain",
# else
#  error
# endif
           rcs_revision, rcs_date);
    if (qic02_get_resources())
    {
        return -ENODEV;
    }
#else
    printk(TPQIC02_NAME ": Runtime config, %s, %s\n", 
           rcs_revision, rcs_date);
#endif
    printk(TPQIC02_NAME ": DMA buffers: %u blocks\n", NR_BLK_BUF);
    /* If we got this far, install driver functions */
    if (register_chrdev(QIC02_TAPE_MAJOR, TPQIC02_NAME, &qic02_tape_fops))
    {
        printk(TPQIC02_NAME ": Unable to get chrdev major %d\n", QIC02_TAPE_MAJOR);
#ifndef CONFIG_QIC02_DYNCONF
        qic02_release_resources();
#endif
        return -ENODEV;
    }

    init_waitqueue_head(&qic02_tape_transfer);
    /* prepare timer */
    TIMEROFF;
    timer_table[QIC02_TAPE_TIMER].expires = 0;
    timer_table[QIC02_TAPE_TIMER].fn = qic02_tape_times_out;
    
#ifndef CONFIG_QIC02_DYNCONF
    if (tape_reset(0)!=TE_OK || tp_sense(TP_WRP|TP_POR|TP_CNI)!=TE_OK)
    {
        /* No drive detected, so vanish */
        tpqputs(TPQD_ALWAYS, "No drive detected -- driver going on vacation...");
        qic02_release_resources();
        status_dead = YES;
        return -ENODEV;
    }
    else
    {
        if (is_exception())
        {
            tpqputs(TPQD_ALWAYS, "exception detected\n");
            (void) tp_sense(TP_WRP|TP_POR|TP_CNI);
        }
    }
#endif

    /* initialize generic status for ioctl requests */
    
    ioctl_status.mt_type        = QIC02_TAPE_DRIVE;     /* MT_IS* id nr */
    
    ioctl_status.mt_resid       = 0;    /* ---residual count */
    ioctl_status.mt_gstat       = 0;    /* ---generic status */
    ioctl_status.mt_erreg       = 0;    /* not used */
    ioctl_status.mt_fileno      = 0;    /* number of current file on tape */
    ioctl_status.mt_blkno       = 0;    /* number of current (logical) block */

    return 0;
} /* qic02_tape_init */

#ifdef MODULE

void cleanup_module(void)
{
    if (status_zombie == NO)
    {
        qic02_release_resources();
    }
    unregister_chrdev(QIC02_TAPE_MAJOR, TPQIC02_NAME);
}

int init_module(void)
{
    int retval;
    retval=qic02_tape_init();
# ifdef CONFIG_QIC02_DYNCONF
    /* This allows the dynamic config program to setup the card
     * by presetting qic02_tape_dynconf via insmod
     */
    if (!retval && qic02_tape_dynconf.ifc_type)
    {
        retval=update_ifc_masks(qic02_tape_dynconf.ifc_type);
        if (retval)
        {
          cleanup_module();
        }
    }
# endif
    return retval;
}
#endif