freebsd-skq/sys/dev/ppbus/ppb_1284.c
Pedro F. Giffuni 718cf2ccb9 sys/dev: further adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
2017-11-27 14:52:40 +00:00

868 lines
18 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* 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.
*
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* General purpose routines for the IEEE1284-1994 Standard
*/
#include "opt_ppb_1284.h"
#include <sys/param.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <dev/ppbus/ppbconf.h>
#include <dev/ppbus/ppb_1284.h>
#include "ppbus_if.h"
#include <dev/ppbus/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, uint8_t mask, uint8_t status)
{
return (ppb_poll_bus(bus, 4, mask, status, PPB_NOINTR | PPB_POLL));
}
static int
do_peripheral_wait(device_t bus, uint8_t mask, uint8_t 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)
{
struct ppb_data *ppb = DEVTOSOFTC(bus);
mtx_assert(ppb->ppc_lock, MA_OWNED);
return (ppb->state);
}
/*
* ppb_1284_set_state()
*
* Change IEEE1284 state if no error occurred
*/
int
ppb_1284_set_state(device_t bus, int state)
{
struct ppb_data *ppb = DEVTOSOFTC(bus);
/* call ppb_1284_reset_error() if you absolutely want to change
* the state from PPB_ERROR to another */
mtx_assert(ppb->ppc_lock, MA_OWNED);
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
printf("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\n", __func__, mode);
}
}
return (request_mode);
}
/*
* ppb_peripheral_negociate()
*
* Negotiate the peripheral side
*/
int
ppb_peripheral_negociate(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_NEGOCIATION);
/* 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
printf("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
printf("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
printf("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
printf("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
printf("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
printf("y");
#endif
/* Event 7 */
error = ppb_poll_bus(bus, PPB_FOREVER, nBUSY, nBUSY,
PPB_INTR);
if (error && error != EWOULDBLOCK)
goto error;
#ifdef DEBUG_1284
printf("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_negociate(bus, mode, 0)))
return (error);
break;
case PPB_REVERSE_IDLE:
terminate_after_transfer = 0;
break;
default:
ppb_1284_terminate(bus);
if ((error = ppb_1284_negociate(bus, mode, 0)))
return (error);
break;
}
while ((len < max) && !(ppb_rstr(bus) & (nFAULT))) {
ppb_1284_set_state(bus, PPB_REVERSE_TRANSFER);
#ifdef DEBUG_1284
printf("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_negociate(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_negociate(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\n", __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_negociate()
*
* 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_negociate(device_t bus, int mode, int options)
{
int error;
int request_mode;
#ifdef DEBUG_1284
printf("n");
#endif
if (ppb_1284_get_state(bus) >= PPB_PERIPHERAL_NEGOCIATION)
ppb_peripheral_terminate(bus, PPB_WAIT);
if (ppb_1284_get_state(bus) != PPB_FORWARD_IDLE)
ppb_1284_terminate(bus);
#ifdef DEBUG_1284
printf("%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_NEGOCIATION);
/* 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
printf("T");
#endif
/* do not reset error here to keep the error that
* may occurred 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);
}