/*-
 * Copyright (c) 1997 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/ppb_1284.c,v 1.11 2000/01/14 08:03:14 nsouch Exp $
 */

/*
 * General purpose routines for the IEEE1284-1994 Standard
 */

#include "opt_ppb_1284.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>

#include <machine/clock.h>

#include "ppbconf.h"
#include "ppb_1284.h"

#include "ppbus_if.h"

#include "ppbio.h"

#define DEVTOSOFTC(dev) ((struct ppb_data *)device_get_softc(dev))

/*
 * do_1284_wait()
 *
 * Wait for the peripherial up to 40ms
 */
static int
do_1284_wait(device_t bus, char mask, char status)
{
        return (ppb_poll_bus(bus, 4, mask, status, PPB_NOINTR | PPB_POLL));
}

static int
do_peripheral_wait(device_t bus, char mask, char status)
{
        return (ppb_poll_bus(bus, 100, mask, status, PPB_NOINTR | PPB_POLL));
}

#define nibble2char(s) (((s & ~nACK) >> 3) | (~s & nBUSY) >> 4)

/*
 * ppb_1284_reset_error()
 *
 * Unconditionaly reset the error field
 */
static int
ppb_1284_reset_error(device_t bus, int state)
{
        struct ppb_data *ppb = DEVTOSOFTC(bus);

        ppb->error = PPB_NO_ERROR;
        ppb->state = state;

        return (0);
}

/*
 * ppb_1284_get_state()
 *
 * Get IEEE1284 state
 */
int
ppb_1284_get_state(device_t bus)
{
        return (DEVTOSOFTC(bus)->state);
}

/*
 * ppb_1284_set_state()
 *
 * Change IEEE1284 state if no error occured
 */
int
ppb_1284_set_state(device_t bus, int state)
{
        struct ppb_data *ppb = DEVTOSOFTC(bus);

        /* call ppb_1284_reset_error() if you absolutly want to change
         * the state from PPB_ERROR to another */
        if ((ppb->state != PPB_ERROR) &&
                        (ppb->error == PPB_NO_ERROR)) {
                ppb->state = state;
                ppb->error = PPB_NO_ERROR;
        }

        return (0);
}

static int
ppb_1284_set_error(device_t bus, int error, int event)
{
        struct ppb_data *ppb = DEVTOSOFTC(bus);

        /* do not accumulate errors */
        if ((ppb->error == PPB_NO_ERROR) &&
                        (ppb->state != PPB_ERROR)) {
                ppb->error = error;
                ppb->state = PPB_ERROR;
        }

#ifdef DEBUG_1284
        kprintf("ppb1284: error=%d status=0x%x event=%d\n", error,
                ppb_rstr(bus) & 0xff, event);
#endif

        return (0);
}

/*
 * ppb_request_mode()
 *
 * Converts mode+options into ext. value
 */
static int
ppb_request_mode(int mode, int options)
{
        int request_mode = 0;

        if (options & PPB_EXTENSIBILITY_LINK) {
                request_mode = EXT_LINK_1284_NORMAL;

        } else {
                switch (mode) {
                case PPB_NIBBLE:
                        request_mode = (options & PPB_REQUEST_ID) ?
                                        NIBBLE_1284_REQUEST_ID :
                                        NIBBLE_1284_NORMAL;
                        break;
                case PPB_PS2:
                        request_mode = (options & PPB_REQUEST_ID) ?
                                        BYTE_1284_REQUEST_ID :
                                        BYTE_1284_NORMAL;
                        break;
                case PPB_ECP:
                        if (options & PPB_USE_RLE)
                                request_mode = (options & PPB_REQUEST_ID) ?
                                        ECP_1284_RLE_REQUEST_ID :
                                        ECP_1284_RLE;
                        else
                                request_mode = (options & PPB_REQUEST_ID) ?
                                        ECP_1284_REQUEST_ID :
                                        ECP_1284_NORMAL;
                        break;
                case PPB_EPP:
                        request_mode = EPP_1284_NORMAL;
                        break;
                default:
                        panic("%s: unsupported mode %d", __func__, mode);
                }
        }

        return (request_mode);
}

/*
 * ppb_peripheral_negotiate()
 *
 * Negotiate the peripheral side
 */
int
ppb_peripheral_negotiate(device_t bus, int mode, int options)
{
        int spin, request_mode, error = 0;
        char r;

        ppb_set_mode(bus, PPB_COMPATIBLE);
        ppb_1284_set_state(bus, PPB_PERIPHERAL_NEGOTIATION);

        /* compute ext. value */
        request_mode = ppb_request_mode(mode, options);

        /* wait host */
        spin = 10;
        while (spin-- && (ppb_rstr(bus) & nBUSY))
                DELAY(1);

        /* check termination */
        if (!(ppb_rstr(bus) & SELECT) || !spin) {
                error = ENODEV;
                goto error;
        }

        /* Event 4 - read ext. value */
        r = ppb_rdtr(bus);

        /* nibble mode is not supported */
        if ((r == (char)request_mode) ||
                        (r == NIBBLE_1284_NORMAL)) {

                /* Event 5 - restore direction bit, no data avail */
                ppb_wctr(bus, (STROBE | nINIT) & ~(SELECTIN));
                DELAY(1);

                /* Event 6 */
                ppb_wctr(bus, (nINIT) & ~(SELECTIN | STROBE));

                if (r == NIBBLE_1284_NORMAL) {
#ifdef DEBUG_1284
                        kprintf("R");
#endif
                        ppb_1284_set_error(bus, PPB_MODE_UNSUPPORTED, 4);
                        error = EINVAL;
                        goto error;
                } else {
                        ppb_1284_set_state(bus, PPB_PERIPHERAL_IDLE);
                        switch (r) {
                        case BYTE_1284_NORMAL:
                                ppb_set_mode(bus, PPB_BYTE);
                                break;
                        default:
                                break;
                        }
#ifdef DEBUG_1284
                        kprintf("A");
#endif
                        /* negotiation succeeds */
                }
        } else {
                /* Event 5 - mode not supported */
                ppb_wctr(bus, SELECTIN);
                DELAY(1);

                /* Event 6 */
                ppb_wctr(bus, (SELECTIN) & ~(STROBE | nINIT));
                ppb_1284_set_error(bus, PPB_MODE_UNSUPPORTED, 4);

#ifdef DEBUG_1284
                kprintf("r");
#endif
                error = EINVAL;
                goto error;
        }

        return (0);

error:
        ppb_peripheral_terminate(bus, PPB_WAIT);
        return (error);
}

/*
 * ppb_peripheral_terminate()
 *
 * Terminate peripheral transfer side
 *
 * Always return 0 in compatible mode
 */
int
ppb_peripheral_terminate(device_t bus, int how)
{
        int error = 0;

#ifdef DEBUG_1284
        kprintf("t");
#endif

        ppb_1284_set_state(bus, PPB_PERIPHERAL_TERMINATION);

        /* Event 22 - wait up to host response time (1s) */
        if ((error = do_peripheral_wait(bus, SELECT | nBUSY, 0))) {
                ppb_1284_set_error(bus, PPB_TIMEOUT, 22);
                goto error;
        }

        /* Event 24 */
        ppb_wctr(bus, (nINIT | STROBE) & ~(AUTOFEED | SELECTIN));

        /* Event 25 - wait up to host response time (1s) */
        if ((error = do_peripheral_wait(bus, nBUSY, nBUSY))) {
                ppb_1284_set_error(bus, PPB_TIMEOUT, 25);
                goto error;
        }

        /* Event 26 */
        ppb_wctr(bus, (SELECTIN | nINIT | STROBE) & ~(AUTOFEED));
        DELAY(1);
        /* Event 27 */
        ppb_wctr(bus, (SELECTIN | nINIT) & ~(STROBE | AUTOFEED));

        /* Event 28 - wait up to host response time (1s) */
        if ((error = do_peripheral_wait(bus, nBUSY, 0))) {
                ppb_1284_set_error(bus, PPB_TIMEOUT, 28);
                goto error;
        }
        
error:
        ppb_set_mode(bus, PPB_COMPATIBLE);
        ppb_1284_set_state(bus, PPB_FORWARD_IDLE);

        return (0);
}

/*
 * byte_peripheral_outbyte()
 *
 * Write 1 byte in BYTE mode
 */
static int
byte_peripheral_outbyte(device_t bus, char *buffer, int last)
{
        int error = 0;

        /* Event 7 */
        if ((error = do_1284_wait(bus, nBUSY, nBUSY))) {
                ppb_1284_set_error(bus, PPB_TIMEOUT, 7);
                goto error;
        }

        /* check termination */
        if (!(ppb_rstr(bus) & SELECT)) {
                ppb_peripheral_terminate(bus, PPB_WAIT);
                goto error;
        }

        /* Event 15 - put byte on data lines */
#ifdef DEBUG_1284
        kprintf("B");
#endif
        ppb_wdtr(bus, *buffer);

        /* Event 9 */
        ppb_wctr(bus, (AUTOFEED | STROBE) & ~(nINIT | SELECTIN));

        /* Event 10 - wait data read */
        if ((error = do_peripheral_wait(bus, nBUSY, 0))) {
                ppb_1284_set_error(bus, PPB_TIMEOUT, 16);
                goto error;
        }

        /* Event 11 */
        if (!last) {
                ppb_wctr(bus, (AUTOFEED) & ~(nINIT | STROBE | SELECTIN));
        } else {
                ppb_wctr(bus, (nINIT) & ~(STROBE | SELECTIN | AUTOFEED));
        }

#if 0
        /* Event 16 - wait strobe */
        if ((error = do_peripheral_wait(bus, nACK | nBUSY, 0))) {
                ppb_1284_set_error(bus, PPB_TIMEOUT, 16);
                goto error;
        }
#endif

        /* check termination */
        if (!(ppb_rstr(bus) & SELECT)) {
                ppb_peripheral_terminate(bus, PPB_WAIT);
                goto error;
        }

error:
        return (error);
}

/*
 * byte_peripheral_write()
 *
 * Write n bytes in BYTE mode
 */
int
byte_peripheral_write(device_t bus, char *buffer, int len, int *sent)
{
        int error = 0, i;
        char r;

        ppb_1284_set_state(bus, PPB_PERIPHERAL_TRANSFER);

        /* wait forever, the remote host is master and should initiate
         * termination
         */
        for (i=0; i<len; i++) {
                /* force remote nFAULT low to release the remote waiting
                 * process, if any
                 */
                r = ppb_rctr(bus);
                ppb_wctr(bus, r & ~nINIT);

#ifdef DEBUG_1284
                kprintf("y");
#endif
                /* Event 7 */
                error = ppb_poll_bus(bus, PPB_FOREVER, nBUSY, nBUSY,
                                        PPB_INTR);

                if (error && error != EWOULDBLOCK)
                        goto error;

#ifdef DEBUG_1284
                kprintf("b");
#endif
                if ((error = byte_peripheral_outbyte(bus, buffer+i, (i == len-1))))
                        goto error;
        }
error:
        if (!error)
                ppb_1284_set_state(bus, PPB_PERIPHERAL_IDLE);

        *sent = i;
        return (error);
}

/*
 * byte_1284_inbyte()
 *
 * Read 1 byte in BYTE mode
 */
int
byte_1284_inbyte(device_t bus, char *buffer)
{
        int error = 0;

        /* Event 7 - ready to take data (nAUTO low) */
        ppb_wctr(bus, (PCD | nINIT | AUTOFEED) & ~(STROBE | SELECTIN));

        /* Event 9 - peripheral set nAck low */
        if ((error = do_1284_wait(bus, nACK, 0))) {
                ppb_1284_set_error(bus, PPB_TIMEOUT, 9);
                goto error;
        }

        /* read the byte */
        *buffer = ppb_rdtr(bus);

        /* Event 10 - data received, can't accept more */
        ppb_wctr(bus, (nINIT) & ~(AUTOFEED | STROBE | SELECTIN));

        /* Event 11 - peripheral ack */
        if ((error = do_1284_wait(bus, nACK, nACK))) {
                ppb_1284_set_error(bus, PPB_TIMEOUT, 11);
                goto error;
        }

        /* Event 16 - strobe */
        ppb_wctr(bus, (nINIT | STROBE) & ~(AUTOFEED | SELECTIN));
        DELAY(3);
        ppb_wctr(bus, (nINIT) & ~(AUTOFEED | STROBE | SELECTIN));

error:
        return (error);
}

/*
 * nibble_1284_inbyte()
 *
 * Read 1 byte in NIBBLE mode
 */
int
nibble_1284_inbyte(device_t bus, char *buffer)
{
        char nibble[2];
        int i, error;

        for (i = 0; i < 2; i++) {

                /* Event 7 - ready to take data (nAUTO low) */
                ppb_wctr(bus, (nINIT | AUTOFEED) & ~(STROBE | SELECTIN));

                /* Event 8 - peripheral writes the first nibble */

                /* Event 9 - peripheral set nAck low */
                if ((error = do_1284_wait(bus, nACK, 0))) {
                        ppb_1284_set_error(bus, PPB_TIMEOUT, 9);
                        goto error;
                }

                /* read nibble */
                nibble[i] = ppb_rstr(bus);

                /* Event 10 - ack, nibble received */
                ppb_wctr(bus, nINIT & ~(AUTOFEED | STROBE | SELECTIN));

                /* Event 11 - wait ack from peripherial */
                if ((error = do_1284_wait(bus, nACK, nACK))) {
                        ppb_1284_set_error(bus, PPB_TIMEOUT, 11);
                        goto error;
                }
        }

        *buffer = ((nibble2char(nibble[1]) << 4) & 0xf0) |
                                (nibble2char(nibble[0]) & 0x0f);

error:
        return (error);
}

/*
 * spp_1284_read()
 *
 * Read in IEEE1284 NIBBLE/BYTE mode
 */
int
spp_1284_read(device_t bus, int mode, char *buffer, int max, int *read)
{
        int error = 0, len = 0;
        int terminate_after_transfer = 1;
        int state;

        *read = len = 0;

        state = ppb_1284_get_state(bus);

        switch (state) {
        case PPB_FORWARD_IDLE:
                if ((error = ppb_1284_negotiate(bus, mode, 0)))
                        return (error);
                break;

        case PPB_REVERSE_IDLE:
                terminate_after_transfer = 0;
                break;
                
        default:
                ppb_1284_terminate(bus);
                if ((error = ppb_1284_negotiate(bus, mode, 0)))
                        return (error);
                break;
        }

        while ((len < max) && !(ppb_rstr(bus) & (nFAULT))) {

                ppb_1284_set_state(bus, PPB_REVERSE_TRANSFER);

#ifdef DEBUG_1284
                kprintf("B");
#endif

                switch (mode) {
                case PPB_NIBBLE:
                        /* read a byte, error means no more data */
                        if (nibble_1284_inbyte(bus, buffer+len))
                                goto end_while;
                        break;
                case PPB_BYTE:
                        if (byte_1284_inbyte(bus, buffer+len))
                                goto end_while;
                        break;
                default:
                        error = EINVAL;
                        goto end_while;
                }
                len ++;
        }
end_while:

        if (!error)
                ppb_1284_set_state(bus, PPB_REVERSE_IDLE);

        *read = len;

        if (terminate_after_transfer || error)
                ppb_1284_terminate(bus);

        return (error);
}

/*
 * ppb_1284_read_id()
 *
 */
int
ppb_1284_read_id(device_t bus, int mode, char *buffer,
                int max, int *read)
{
        int error = 0;

        /* fill the buffer with 0s */
        bzero(buffer, max);

        switch (mode) {
        case PPB_NIBBLE:
        case PPB_ECP:
                if ((error = ppb_1284_negotiate(bus, PPB_NIBBLE, PPB_REQUEST_ID)))
                        return (error);
                error = spp_1284_read(bus, PPB_NIBBLE, buffer, max, read);
                break;
        case PPB_BYTE:
                if ((error = ppb_1284_negotiate(bus, PPB_BYTE, PPB_REQUEST_ID)))
                        return (error);
                error = spp_1284_read(bus, PPB_BYTE, buffer, max, read);
                break;
        default:
                panic("%s: unsupported mode %d", __func__, mode);
        }

        ppb_1284_terminate(bus);
        return (error);
}

/*
 * ppb_1284_read()
 *
 * IEEE1284 read
 */
int
ppb_1284_read(device_t bus, int mode, char *buffer,
                int max, int *read)
{
        int error = 0;

        switch (mode) {
        case PPB_NIBBLE:
        case PPB_BYTE:
                error = spp_1284_read(bus, mode, buffer, max, read);
                break;
        default:
                return (EINVAL);
        }

        return (error);
}

/*
 * ppb_1284_negotiate()
 *
 * IEEE1284 negotiation phase
 *
 * Normal nibble mode or request device id mode (see ppb_1284.h)
 *
 * After negotiation, nFAULT is low if data is available
 */
int
ppb_1284_negotiate(device_t bus, int mode, int options)
{
        int error;
        int request_mode;

#ifdef DEBUG_1284
        kprintf("n");
#endif

        if (ppb_1284_get_state(bus) >= PPB_PERIPHERAL_NEGOTIATION)
                ppb_peripheral_terminate(bus, PPB_WAIT);

        if (ppb_1284_get_state(bus) != PPB_FORWARD_IDLE)
                ppb_1284_terminate(bus);

#ifdef DEBUG_1284
        kprintf("%d", mode);
#endif

        /* ensure the host is in compatible mode */
        ppb_set_mode(bus, PPB_COMPATIBLE);

        /* reset error to catch the actual negotiation error */
        ppb_1284_reset_error(bus, PPB_FORWARD_IDLE);

        /* calculate ext. value */
        request_mode = ppb_request_mode(mode, options);

        /* default state */
        ppb_wctr(bus, (nINIT | SELECTIN) & ~(STROBE | AUTOFEED));
        DELAY(1);

        /* enter negotiation phase */
        ppb_1284_set_state(bus, PPB_NEGOTIATION);

        /* Event 0 - put the exten. value on the data lines */
        ppb_wdtr(bus, request_mode);

#ifdef PERIPH_1284
        /* request remote host attention */
        ppb_wctr(bus, (nINIT | STROBE) & ~(AUTOFEED | SELECTIN));
        DELAY(1);
        ppb_wctr(bus, (nINIT) & ~(STROBE | AUTOFEED | SELECTIN));
#else
        DELAY(1);

#endif /* !PERIPH_1284 */

        /* Event 1 - enter IEEE1284 mode */
        ppb_wctr(bus, (nINIT | AUTOFEED) & ~(STROBE | SELECTIN));

#ifdef PERIPH_1284
        /* ignore the PError line, wait a bit more, remote host's 
         * interrupts don't respond fast enough */
        if (ppb_poll_bus(bus, 40, nACK | SELECT | nFAULT,
                                SELECT | nFAULT, PPB_NOINTR | PPB_POLL)) {
                ppb_1284_set_error(bus, PPB_NOT_IEEE1284, 2);
                error = ENODEV;
                goto error;
        }
#else
        /* Event 2 - trying IEEE1284 dialog */
        if (do_1284_wait(bus, nACK | PERROR | SELECT | nFAULT,
                        PERROR  | SELECT | nFAULT)) {
                ppb_1284_set_error(bus, PPB_NOT_IEEE1284, 2);
                error = ENODEV;
                goto error;
        }
#endif /* !PERIPH_1284 */

        /* Event 3 - latch the ext. value to the peripheral */
        ppb_wctr(bus, (nINIT | STROBE | AUTOFEED) & ~SELECTIN);
        DELAY(1);

        /* Event 4 - IEEE1284 device recognized */
        ppb_wctr(bus, nINIT & ~(SELECTIN | AUTOFEED | STROBE));

        /* Event 6 - waiting for status lines */
        if (do_1284_wait(bus, nACK, nACK)) {
                ppb_1284_set_error(bus, PPB_TIMEOUT, 6);
                error = EBUSY;
                goto error;
        }

        /* Event 7 - quering result consider nACK not to misunderstand
         * a remote computer terminate sequence */
        if (options & PPB_EXTENSIBILITY_LINK) {

                /* XXX not fully supported yet */
                ppb_1284_terminate(bus);
                return (0);

        }
        if (request_mode == NIBBLE_1284_NORMAL) {
                if (do_1284_wait(bus, nACK | SELECT, nACK)) {
                        ppb_1284_set_error(bus, PPB_MODE_UNSUPPORTED, 7);
                        error = ENODEV;
                        goto error;
                }
        } else {
                if (do_1284_wait(bus, nACK | SELECT, SELECT | nACK)) {
                        ppb_1284_set_error(bus, PPB_MODE_UNSUPPORTED, 7);
                        error = ENODEV;
                        goto error;
                }
        }

        switch (mode) {
        case PPB_NIBBLE:
        case PPB_PS2:
                /* enter reverse idle phase */
                ppb_1284_set_state(bus, PPB_REVERSE_IDLE);
                break;
        case PPB_ECP:
                /* negotiation ok, now setup the communication */
                ppb_1284_set_state(bus, PPB_SETUP);
                ppb_wctr(bus, (nINIT | AUTOFEED) & ~(SELECTIN | STROBE));

#ifdef PERIPH_1284
                /* ignore PError line */
                if (do_1284_wait(bus, nACK | SELECT | nBUSY,
                                        nACK | SELECT | nBUSY)) {
                        ppb_1284_set_error(bus, PPB_TIMEOUT, 30);
                        error = ENODEV;
                        goto error;
                }
#else
                if (do_1284_wait(bus, nACK | SELECT | PERROR | nBUSY,
                                        nACK | SELECT | PERROR | nBUSY)) {
                        ppb_1284_set_error(bus, PPB_TIMEOUT, 30);
                        error = ENODEV;
                        goto error;
                }
#endif /* !PERIPH_1284 */

                /* ok, the host enters the ForwardIdle state */
                ppb_1284_set_state(bus, PPB_ECP_FORWARD_IDLE);
                break;
        case PPB_EPP:
                ppb_1284_set_state(bus, PPB_EPP_IDLE);
                break;

        default:
                panic("%s: unknown mode (%d)!", __func__, mode);
        }
        ppb_set_mode(bus, mode);

        return (0);

error:
        ppb_1284_terminate(bus);

        return (error);
}

/*
 * ppb_1284_terminate()
 *
 * IEEE1284 termination phase, return code should ignored since the host
 * is _always_ in compatible mode after ppb_1284_terminate()
 */
int
ppb_1284_terminate(device_t bus)
{

#ifdef DEBUG_1284
        kprintf("T");
#endif

        /* do not reset error here to keep the error that
         * may occured before the ppb_1284_terminate() call */
        ppb_1284_set_state(bus, PPB_TERMINATION);

#ifdef PERIPH_1284
        /* request remote host attention */
        ppb_wctr(bus, (nINIT | STROBE | SELECTIN) & ~(AUTOFEED));
        DELAY(1);
#endif /* PERIPH_1284 */

        /* Event 22 - set nSelectin low and nAutoFeed high */
        ppb_wctr(bus, (nINIT | SELECTIN) & ~(STROBE | AUTOFEED));

        /* Event 24 - waiting for peripheral, Xflag ignored */
        if (do_1284_wait(bus, nACK | nBUSY | nFAULT, nFAULT)) {
                ppb_1284_set_error(bus, PPB_TIMEOUT, 24);
                goto error;
        }

        /* Event 25 - set nAutoFd low */
        ppb_wctr(bus, (nINIT | SELECTIN | AUTOFEED) & ~STROBE);

        /* Event 26 - compatible mode status is set */

        /* Event 27 - peripheral set nAck high */
        if (do_1284_wait(bus, nACK, nACK)) {
                ppb_1284_set_error(bus, PPB_TIMEOUT, 27);
        }

        /* Event 28 - end termination, return to idle phase */
        ppb_wctr(bus, (nINIT | SELECTIN) & ~(STROBE | AUTOFEED));

error:
        /* return to compatible mode */
        ppb_set_mode(bus, PPB_COMPATIBLE);
        ppb_1284_set_state(bus, PPB_FORWARD_IDLE);

        return (0);
}