kmalloc: Avoid code duplication.

[dragonfly.git] / sys / dev / disk / vpo / immio.c

/*-
 * Copyright (c) 1998, 1999 Nicolas Souchu
 * Copyright (c) 2001 Alcove - Nicolas Souchu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/sys/dev/ppbus/immio.c,v 1.10.2.3 2001/10/02 05:27:20 nsouch Exp $
 */

/*
 * Iomega ZIP+ Matchmaker Parallel Port Interface driver
 *
 * Thanks to David Campbell work on the Linux driver and the Iomega specs
 * Thanks to Thiebault Moeglin for the drive
 */
#ifdef _KERNEL
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/module.h>
#include <sys/bus.h>
#include <sys/malloc.h>

#endif  /* _KERNEL */

#include "opt_vpo.h"

#include <bus/ppbus/ppbio.h>
#include <bus/ppbus/ppbconf.h>
#include <bus/ppbus/ppb_msq.h>
#include "vpoio.h"
#include <bus/ppbus/ppb_1284.h>

#include "ppbus_if.h"

#define VP0_SELTMO              5000    /* select timeout */
#define VP0_FAST_SPINTMO        500000  /* wait status timeout */
#define VP0_LOW_SPINTMO         5000000 /* wait status timeout */

#define VP0_SECTOR_SIZE 512

/*
 * Microcode to execute very fast I/O sequences at the lowest bus level.
 */

#define WAIT_RET                MS_PARAM(7, 2, MS_TYP_PTR)
#define WAIT_TMO                MS_PARAM(1, 0, MS_TYP_INT)

#define DECLARE_WAIT_MICROSEQUENCE \
struct ppb_microseq wait_microseq[] = {                                 \
        MS_CASS(0x0c),                                                  \
        MS_SET(MS_UNKNOWN),                                             \
        /* loop */                                                      \
        MS_BRSET(nBUSY, 4 /* ready */),                                 \
        MS_DBRA(-2 /* loop */),                                         \
        MS_CASS(0x04),                                                  \
        MS_RET(1), /* timed out */                                      \
        /* ready */                                                     \
        MS_CASS(0x04),                                                  \
        MS_RFETCH(MS_REG_STR, 0xb8, MS_UNKNOWN ),                       \
        MS_RET(0) /* no error */                                        \
}

#define SELECT_TARGET           MS_PARAM(6, 1, MS_TYP_CHA)

#define DECLARE_SELECT_MICROSEQUENCE \
struct ppb_microseq select_microseq[] = {                               \
        MS_CASS(0xc),                                                   \
        /* first, check there is nothing holding onto the bus */        \
        MS_SET(VP0_SELTMO),                                             \
/* _loop: */                                                            \
        MS_BRCLEAR(0x8, 2 /* _ready */),                                \
        MS_DBRA(-2 /* _loop */),                                        \
        MS_RET(2),                      /* bus busy */                  \
/* _ready: */                                                           \
        MS_CASS(0x4),                                                   \
        MS_DASS(MS_UNKNOWN /* 0x80 | 1 << target */),                   \
        MS_DELAY(1),                                                    \
        MS_CASS(0xc),                                                   \
        MS_CASS(0xd),                                                   \
        /* now, wait until the drive is ready */                        \
        MS_SET(VP0_SELTMO),                                             \
/* loop: */                                                             \
        MS_BRSET(0x8, 3 /* ready */),                                   \
        MS_DBRA(-2 /* loop */),                                         \
/* error: */                                                            \
        MS_CASS(0xc),                                                   \
        MS_RET(VP0_ESELECT_TIMEOUT),                                    \
/* ready: */                                                            \
        MS_CASS(0xc),                                                   \
        MS_RET(0)                                                       \
}

static struct ppb_microseq transfer_epilog[] = {
        MS_CASS(0x4),
        MS_CASS(0xc),
        MS_CASS(0xe),
        MS_CASS(0x4),
        MS_RET(0)
};

#define CPP_S1          MS_PARAM(10, 2, MS_TYP_PTR)
#define CPP_S2          MS_PARAM(13, 2, MS_TYP_PTR)
#define CPP_S3          MS_PARAM(16, 2, MS_TYP_PTR)
#define CPP_PARAM       MS_PARAM(17, 1, MS_TYP_CHA)

#define DECLARE_CPP_MICROSEQ \
struct ppb_microseq cpp_microseq[] = {                                  \
        MS_CASS(0x0c), MS_DELAY(2),                                     \
        MS_DASS(0xaa), MS_DELAY(10),                                    \
        MS_DASS(0x55), MS_DELAY(10),                                    \
        MS_DASS(0x00), MS_DELAY(10),                                    \
        MS_DASS(0xff), MS_DELAY(10),                                    \
        MS_RFETCH(MS_REG_STR, 0xb8, MS_UNKNOWN /* &s1 */),              \
        MS_DASS(0x87), MS_DELAY(10),                                    \
        MS_RFETCH(MS_REG_STR, 0xb8, MS_UNKNOWN /* &s2 */),              \
        MS_DASS(0x78), MS_DELAY(10),                                    \
        MS_RFETCH(MS_REG_STR, 0x38, MS_UNKNOWN /* &s3 */),              \
        MS_DASS(MS_UNKNOWN /* param */),                                \
        MS_DELAY(2),                                                    \
        MS_CASS(0x0c), MS_DELAY(10),                                    \
        MS_CASS(0x0d), MS_DELAY(2),                                     \
        MS_CASS(0x0c), MS_DELAY(10),                                    \
        MS_DASS(0xff), MS_DELAY(10),                                    \
        MS_RET(0)                                                       \
}

#define NEGOCIATED_MODE         MS_PARAM(2, 1, MS_TYP_CHA)

#define DECLARE_NEGOCIATE_MICROSEQ \
struct ppb_microseq negociate_microseq[] = {                            \
        MS_CASS(0x4),                                                   \
        MS_DELAY(5),                                                    \
        MS_DASS(MS_UNKNOWN /* mode */),                                 \
        MS_DELAY(100),                                                  \
        MS_CASS(0x6),                                                   \
        MS_DELAY(5),                                                    \
        MS_BRSET(0x20, 5 /* continue */),                               \
        MS_DELAY(5),                                                    \
        MS_CASS(0x7),                                                   \
        MS_DELAY(5),                                                    \
        MS_CASS(0x6),                                                   \
        MS_RET(VP0_ENEGOCIATE),                                         \
/* continue: */                                                         \
        MS_DELAY(5),                                                    \
        MS_CASS(0x7),                                                   \
        MS_DELAY(5),                                                    \
        MS_CASS(0x6),                                                   \
        MS_RET(0)                                                       \
}

#define INB_NIBBLE_L MS_PARAM(3, 2, MS_TYP_PTR)
#define INB_NIBBLE_H MS_PARAM(6, 2, MS_TYP_PTR)
#define INB_NIBBLE_F MS_PARAM(9, 0, MS_TYP_FUN)
#define INB_NIBBLE_P MS_PARAM(9, 1, MS_TYP_PTR)

/*
 * This is the sub-microseqence for MS_GET in NIBBLE mode
 * Retrieve the two nibbles and call the C function to generate the character
 * and store it in the buffer (see nibble_inbyte_hook())
 */

#define DECLARE_NIBBLE_INBYTE_SUBMICROSEQ \
struct ppb_microseq nibble_inbyte_submicroseq[] = {                     \
        MS_CASS(0x4),                                                   \
/* loop: */                                                             \
        MS_CASS(0x6),                                                   \
        MS_DELAY(1),                                                    \
        MS_RFETCH(MS_REG_STR, MS_FETCH_ALL, MS_UNKNOWN /* low nibble */),\
        MS_CASS(0x5),                                                   \
        MS_DELAY(1),                                                    \
        MS_RFETCH(MS_REG_STR, MS_FETCH_ALL, MS_UNKNOWN /* high nibble */),\
        MS_CASS(0x4),                                                   \
        MS_DELAY(1),                                                    \
        /* do a C call to format the received nibbles */                \
        MS_C_CALL(MS_UNKNOWN /* C hook */, MS_UNKNOWN /* param */),     \
        MS_DBRA(-7 /* loop */),                                         \
        MS_RET(0)                                                       \
}

static struct ppb_microseq reset_microseq[] = {
        MS_CASS(0x04),
        MS_DASS(0x40),
        MS_DELAY(1),
        MS_CASS(0x0c),
        MS_CASS(0x0d),
        MS_DELAY(50),
        MS_CASS(0x0c),
        MS_CASS(0x04),
        MS_RET(0)
};

/*
 * nibble_inbyte_hook()
 *
 * Formats high and low nibble into a character
 */
static int
nibble_inbyte_hook (void *p, char *ptr)
{
        struct vpo_nibble *s = (struct vpo_nibble *)p;

        /* increment the buffer pointer */
        *ptr = ((s->l >> 4) & 0x0f) + (s->h & 0xf0);

        return (0);
}

/*
 * This is the sub-microseqence for MS_GET in PS2 mode
 */
static struct ppb_microseq ps2_inbyte_submicroseq[] = {
          MS_CASS(0x4),

/* loop: */
          MS_CASS(PCD | 0x6),
          MS_RFETCH_P(1, MS_REG_DTR, MS_FETCH_ALL),
          MS_CASS(PCD | 0x5),
          MS_DBRA(-4 /* loop */),

          MS_RET(0)
};

/*
 * This is the sub-microsequence for MS_PUT in both NIBBLE and PS2 modes
 */
static struct ppb_microseq spp_outbyte_submicroseq[] = {
          MS_CASS(0x4),

/* loop: */
          MS_RASSERT_P(1, MS_REG_DTR), 
          MS_CASS(0x5),
          MS_DBRA(0),                           /* decrement counter */
          MS_RASSERT_P(1, MS_REG_DTR), 
          MS_CASS(0x0),
          MS_DBRA(-6 /* loop */),

          /* return from the put call */
          MS_CASS(0x4),
          MS_RET(0)
};

/* EPP 1.7 microsequences, ptr and len set at runtime */
static struct ppb_microseq epp17_outstr[] = {
          MS_CASS(0x4),
          MS_RASSERT_P(MS_ACCUM, MS_REG_EPP_D), 
          MS_CASS(0xc),
          MS_RET(0),
};

static struct ppb_microseq epp17_instr[] = {
          MS_CASS(PCD | 0x4),
          MS_RFETCH_P(MS_ACCUM, MS_REG_EPP_D, MS_FETCH_ALL), 
          MS_CASS(PCD | 0xc),
          MS_RET(0),
};

static int
imm_disconnect(struct vpoio_data *vpo, int *connected, int release_bus)
{
        DECLARE_CPP_MICROSEQ;

        device_t ppbus = device_get_parent(vpo->vpo_dev);
        char s1, s2, s3;
        int ret;

        /* all should be ok */
        if (connected)
                *connected = 0;

        ppb_MS_init_msq(cpp_microseq, 4, CPP_S1, (void *)&s1,
                        CPP_S2, (void *)&s2, CPP_S3, (void *)&s3,
                        CPP_PARAM, 0x30);

        ppb_MS_microseq(ppbus, vpo->vpo_dev, cpp_microseq, &ret);

        if ((s1 != (char)0xb8 || s2 != (char)0x18 || s3 != (char)0x38)) {
                if (bootverbose)
                        kprintf("imm%d: (disconnect) s1=0x%x s2=0x%x, s3=0x%x\n",
                                vpo->vpo_unit, s1 & 0xff, s2 & 0xff, s3 & 0xff);
                if (connected)
                        *connected = VP0_ECONNECT;
        }

        if (release_bus)
                return (ppb_release_bus(ppbus, vpo->vpo_dev));
        else
                return (0);
}

/*
 * how  : PPB_WAIT or PPB_DONTWAIT
 */
static int
imm_connect(struct vpoio_data *vpo, int how, int *disconnected, int request_bus)
{
        DECLARE_CPP_MICROSEQ;

        device_t ppbus = device_get_parent(vpo->vpo_dev);
        char s1, s2, s3;
        int error;
        int ret;

        /* all should be ok */
        if (disconnected)
                *disconnected = 0;

        if (request_bus)
                if ((error = ppb_request_bus(ppbus, vpo->vpo_dev, how)))
                        return (error);

        ppb_MS_init_msq(cpp_microseq, 3, CPP_S1, (void *)&s1,
                        CPP_S2, (void *)&s2, CPP_S3, (void *)&s3);

        /* select device 0 in compatible mode */
        ppb_MS_init_msq(cpp_microseq, 1, CPP_PARAM, 0xe0);
        ppb_MS_microseq(ppbus, vpo->vpo_dev, cpp_microseq, &ret);

        /* disconnect all devices */
        ppb_MS_init_msq(cpp_microseq, 1, CPP_PARAM, 0x30);
        ppb_MS_microseq(ppbus, vpo->vpo_dev, cpp_microseq, &ret);

        if (PPB_IN_EPP_MODE(ppbus))
                ppb_MS_init_msq(cpp_microseq, 1, CPP_PARAM, 0x28);
        else
                ppb_MS_init_msq(cpp_microseq, 1, CPP_PARAM, 0xe0);

        ppb_MS_microseq(ppbus, vpo->vpo_dev, cpp_microseq, &ret);

        if ((s1 != (char)0xb8 || s2 != (char)0x18 || s3 != (char)0x30)) {
                if (bootverbose)
                        kprintf("imm%d: (connect) s1=0x%x s2=0x%x, s3=0x%x\n",
                                vpo->vpo_unit, s1 & 0xff, s2 & 0xff, s3 & 0xff);
                if (disconnected)
                        *disconnected = VP0_ECONNECT;
        }

        return (0);
}

/*
 * imm_detect()
 *
 * Detect and initialise the VP0 adapter.
 */
static int
imm_detect(struct vpoio_data *vpo)
{
        device_t ppbus = device_get_parent(vpo->vpo_dev);
        int error;

        if ((error = ppb_request_bus(ppbus, vpo->vpo_dev, PPB_DONTWAIT)))
                return (error);

        /* disconnect the drive, keep the bus */
        imm_disconnect(vpo, NULL, 0);

        vpo->vpo_mode_found = VP0_MODE_UNDEFINED;
        error = 1;

        /* try to enter EPP mode since vpoio failure put the bus in NIBBLE */
        if (ppb_set_mode(ppbus, PPB_EPP) != -1) {
                imm_connect(vpo, PPB_DONTWAIT, &error, 0);
        }

        /* if connection failed try PS/2 then NIBBLE modes */
        if (error) {
                if (ppb_set_mode(ppbus, PPB_PS2) != -1) {
                        imm_connect(vpo, PPB_DONTWAIT, &error, 0);
                }
                if (error) {
                        if (ppb_set_mode(ppbus, PPB_NIBBLE) != -1) {
                                imm_connect(vpo, PPB_DONTWAIT, &error, 0);
                                if (error)
                                        goto error;
                                vpo->vpo_mode_found = VP0_MODE_NIBBLE;
                        } else {
                                kprintf("imm%d: NIBBLE mode unavailable!\n", vpo->vpo_unit);
                                goto error;
                        }
                } else {
                        vpo->vpo_mode_found = VP0_MODE_PS2;
                }
        } else {
                vpo->vpo_mode_found = VP0_MODE_EPP;
        }

        /* send SCSI reset signal */
        ppb_MS_microseq(ppbus, vpo->vpo_dev, reset_microseq, NULL);

        /* release the bus now */
        imm_disconnect(vpo, &error, 1);

        /* ensure we are disconnected or daisy chained peripheral 
         * may cause serious problem to the disk */

        if (error) {
                if (bootverbose)
                        kprintf("imm%d: can't disconnect from the drive\n",
                                vpo->vpo_unit);
                goto error;
        }

        return (0);

error:
        ppb_release_bus(ppbus, vpo->vpo_dev);
        return (VP0_EINITFAILED);
}

/*
 * imm_outstr()
 */
static int
imm_outstr(struct vpoio_data *vpo, char *_buffer, int _size)
{
        union ppb_insarg buffer = { .c = _buffer };
        union ppb_insarg size = { .i = _size };
        union ppb_insarg unknown = { .i = MS_UNKNOWN };
        device_t ppbus = device_get_parent(vpo->vpo_dev);
        int error = 0;

        if (PPB_IN_EPP_MODE(ppbus))
                ppb_reset_epp_timeout(ppbus);

        ppb_MS_exec(ppbus, vpo->vpo_dev, MS_OP_PUT, buffer, size, unknown,
            &error);

        return (error);
}

/*
 * imm_instr()
 */
static int
imm_instr(struct vpoio_data *vpo, char *_buffer, int _size)
{
        union ppb_insarg buffer = { .c = _buffer };
        union ppb_insarg size = { .i = _size };
        union ppb_insarg unknown = { .i = MS_UNKNOWN };
        device_t ppbus = device_get_parent(vpo->vpo_dev);
        int error = 0;

        if (PPB_IN_EPP_MODE(ppbus))
                ppb_reset_epp_timeout(ppbus);

        ppb_MS_exec(ppbus, vpo->vpo_dev, MS_OP_GET, buffer, size, unknown,
            &error);

        return (error);
}

static char
imm_select(struct vpoio_data *vpo, int initiator, int target)
{
        DECLARE_SELECT_MICROSEQUENCE;
        device_t ppbus = device_get_parent(vpo->vpo_dev);
        int ret;

        /* initialize the select microsequence */
        ppb_MS_init_msq(select_microseq, 1,
                        SELECT_TARGET, 1 << initiator | 1 << target);
                                
        ppb_MS_microseq(ppbus, vpo->vpo_dev, select_microseq, &ret);

        return (ret);
}

/*
 * imm_wait()
 *
 * H_SELIN must be low.
 *
 */
static char
imm_wait(struct vpoio_data *vpo, int tmo)
{
        DECLARE_WAIT_MICROSEQUENCE;

        device_t ppbus = device_get_parent(vpo->vpo_dev);
        int ret, err;

        /*
         * Return some status information.
         * Semantics :  0x88 = ZIP+ wants more data
         *              0x98 = ZIP+ wants to send more data
         *              0xa8 = ZIP+ wants command
         *              0xb8 = end of transfer, ZIP+ is sending status
         */

        ppb_MS_init_msq(wait_microseq, 2,
                        WAIT_RET, (void *)&ret,
                        WAIT_TMO, tmo);

        ppb_MS_microseq(ppbus, vpo->vpo_dev, wait_microseq, &err);

        if (err)
                return (0);                        /* command timed out */      

        return(ret);
}

static int
imm_negociate(struct vpoio_data *vpo)
{
        DECLARE_NEGOCIATE_MICROSEQ;
        device_t ppbus = device_get_parent(vpo->vpo_dev);
        int negociate_mode;
        int ret;

        if (PPB_IN_NIBBLE_MODE(ppbus))
                negociate_mode = 0;
        else if (PPB_IN_PS2_MODE(ppbus))
                negociate_mode = 1;
        else
                return (0);

#if 0 /* XXX use standalone code not to depend on ppb_1284 code yet */
        ret = ppb_1284_negociate(ppbus, negociate_mode);

        if (ret)
                return (VP0_ENEGOCIATE);
#endif
        
        ppb_MS_init_msq(negociate_microseq, 1,
                        NEGOCIATED_MODE, negociate_mode);

        ppb_MS_microseq(ppbus, vpo->vpo_dev, negociate_microseq, &ret);

        return (ret);
}

/*
 * imm_probe()
 *
 * Low level probe of vpo device
 *
 */
int
imm_probe(device_t dev, struct vpoio_data *vpo)
{
        int error;

        /* ppbus dependent initialisation */
        vpo->vpo_dev = dev;

        /* now, try to initialise the drive */
        if ((error = imm_detect(vpo))) {
                return (error);
        }

        return (0);
}

/*
 * imm_attach()
 *
 * Low level attachment of vpo device
 *
 */
int
imm_attach(struct vpoio_data *vpo)
{
        DECLARE_NIBBLE_INBYTE_SUBMICROSEQ;      
        device_t ppbus = device_get_parent(vpo->vpo_dev);
        int error = 0;

        /*
         * Initialize microsequence code
         */
        vpo->vpo_nibble_inbyte_msq = kmalloc(sizeof(nibble_inbyte_submicroseq),
                                                M_DEVBUF, M_WAITOK);

        bcopy((void *)nibble_inbyte_submicroseq,
                (void *)vpo->vpo_nibble_inbyte_msq,
                sizeof(nibble_inbyte_submicroseq));

        ppb_MS_init_msq(vpo->vpo_nibble_inbyte_msq, 4,
                INB_NIBBLE_H, (void *)&(vpo)->vpo_nibble.h,
                INB_NIBBLE_L, (void *)&(vpo)->vpo_nibble.l,
                INB_NIBBLE_F, nibble_inbyte_hook,
                INB_NIBBLE_P, (void *)&(vpo)->vpo_nibble); 

        /*
         * Initialize mode dependent in/out microsequences
         */
        if ((error = ppb_request_bus(ppbus, vpo->vpo_dev, PPB_WAIT)))
            goto error;

        /* ppbus automatically restore the last mode entered during detection */
        switch (vpo->vpo_mode_found) {
        case VP0_MODE_EPP:
                ppb_MS_GET_init(ppbus, vpo->vpo_dev, epp17_instr);
                ppb_MS_PUT_init(ppbus, vpo->vpo_dev, epp17_outstr);
                kprintf("imm%d: EPP mode\n", vpo->vpo_unit);
                break;
        case VP0_MODE_PS2:
                ppb_MS_GET_init(ppbus, vpo->vpo_dev, ps2_inbyte_submicroseq);
                ppb_MS_PUT_init(ppbus, vpo->vpo_dev, spp_outbyte_submicroseq);
                kprintf("imm%d: PS2 mode\n", vpo->vpo_unit);
                break;
        case VP0_MODE_NIBBLE:
                ppb_MS_GET_init(ppbus, vpo->vpo_dev, vpo->vpo_nibble_inbyte_msq);
                ppb_MS_PUT_init(ppbus, vpo->vpo_dev, spp_outbyte_submicroseq);
                kprintf("imm%d: NIBBLE mode\n", vpo->vpo_unit);
                break;
        default:
                panic("imm: unknown mode %d", vpo->vpo_mode_found);
        }

        ppb_release_bus(ppbus, vpo->vpo_dev);
 error:
        return (error);
}

/*
 * imm_reset_bus()
 *
 */
int
imm_reset_bus(struct vpoio_data *vpo)
{
        device_t ppbus = device_get_parent(vpo->vpo_dev);
        int disconnected;

        /* first, connect to the drive and request the bus */
        imm_connect(vpo, PPB_WAIT|PPB_INTR, &disconnected, 1);

        if (!disconnected) {

                /* reset the SCSI bus */
                ppb_MS_microseq(ppbus, vpo->vpo_dev, reset_microseq, NULL);

                /* then disconnect */
                imm_disconnect(vpo, NULL, 1);
        }

        return (0);
}

/*
 * imm_do_scsi()
 *
 * Send an SCSI command
 *
 */
int 
imm_do_scsi(struct vpoio_data *vpo, int host, int target, char *command,
                int clen, char *buffer, int blen, int *result, int *count,
                int *ret)
{
        device_t ppbus = device_get_parent(vpo->vpo_dev);
        char r;
        char l, h = 0;
        int len, error = 0, not_connected = 0;
        int k;
        int negociated = 0;

        /*
         * enter disk state, allocate the ppbus
         *
         * XXX
         * Should we allow this call to be interruptible?
         * The only way to report the interruption is to return
         * EIO to upper SCSI code :^(
         */
        if ((error = imm_connect(vpo, PPB_WAIT|PPB_INTR, &not_connected, 1)))
                return (error);

        if (not_connected) {
                *ret = VP0_ECONNECT; goto error;
        }

        /*
         * Select the drive ...
         */
        if ((*ret = imm_select(vpo,host,target)))
                goto error;

        /*
         * Send the command ...
         */
        for (k = 0; k < clen; k+=2) {
                if (imm_wait(vpo, VP0_FAST_SPINTMO) != (char)0xa8) {
                        *ret = VP0_ECMD_TIMEOUT;
                        goto error;
                }
                if (imm_outstr(vpo, &command[k], 2)) {
                        *ret = VP0_EPPDATA_TIMEOUT;
                        goto error;
                }
        }

        if (!(r = imm_wait(vpo, VP0_LOW_SPINTMO))) {
                *ret = VP0_ESTATUS_TIMEOUT; goto error;
        }

        if ((r & 0x30) == 0x10) {
                if (imm_negociate(vpo)) {
                        *ret = VP0_ENEGOCIATE;
                        goto error;
                } else
                        negociated = 1;
        }

        /* 
         * Complete transfer ... 
         */
        *count = 0;
        for (;;) {

                if (!(r = imm_wait(vpo, VP0_LOW_SPINTMO))) {
                        *ret = VP0_ESTATUS_TIMEOUT; goto error;
                }

                /* stop when the ZIP+ wants to send status */
                if (r == (char)0xb8)
                        break;

                if (*count >= blen) {
                        *ret = VP0_EDATA_OVERFLOW;
                        goto error;
                }

                /* ZIP+ wants to send data? */
                if (r == (char)0x88) {
                        len = (((blen - *count) >= VP0_SECTOR_SIZE)) ?
                                VP0_SECTOR_SIZE : 2;

                        error = imm_outstr(vpo, &buffer[*count], len);
                } else {
                        if (!PPB_IN_EPP_MODE(ppbus))
                                len = 1;
                        else
                                len = (((blen - *count) >= VP0_SECTOR_SIZE)) ?
                                        VP0_SECTOR_SIZE : 1;

                        error = imm_instr(vpo, &buffer[*count], len);
                }

                if (error) {
                        *ret = error;
                        goto error;
                }

                *count += len;
        }

        if ((PPB_IN_NIBBLE_MODE(ppbus) ||
                        PPB_IN_PS2_MODE(ppbus)) && negociated)
                ppb_MS_microseq(ppbus, vpo->vpo_dev, transfer_epilog, NULL);

        /*
         * Retrieve status ...
         */
        if (imm_negociate(vpo)) {
                *ret = VP0_ENEGOCIATE;
                goto error;
        } else
                negociated = 1;

        if (imm_instr(vpo, &l, 1)) {
                *ret = VP0_EOTHER; goto error;
        }

        /* check if the ZIP+ wants to send more status */
        if (imm_wait(vpo, VP0_FAST_SPINTMO) == (char)0xb8)
                if (imm_instr(vpo, &h, 1)) {
                        *ret = VP0_EOTHER+2; goto error;
                }

        /* Experience showed that we should discard this */
        if (h == -1)
                h = 0;

        *result = ((int) h << 8) | ((int) l & 0xff);

error:
        if ((PPB_IN_NIBBLE_MODE(ppbus) ||
                        PPB_IN_PS2_MODE(ppbus)) && negociated)
                ppb_MS_microseq(ppbus, vpo->vpo_dev, transfer_epilog, NULL);

        /* return to printer state, release the ppbus */
        imm_disconnect(vpo, NULL, 1);

        return (0);
}