| Current Path : /sys/amd64/compile/hs32/modules/usr/src/sys/modules/ae/@/dev/ppbus/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //sys/amd64/compile/hs32/modules/usr/src/sys/modules/ae/@/dev/ppbus/ppb_1284.c |
/*-
* 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: release/9.1.0/sys/dev/ppbus/ppb_1284.c 187576 2009-01-21 23:10:06Z jhb $");
/*
* 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, 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)
{
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 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 */
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()
*
* Negociate 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
/* negociation 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 negociation phase
*
* Normal nibble mode or request device id mode (see ppb_1284.h)
*
* After negociation, 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 negociation 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 negociation 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:
/* negociation 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 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);
}