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linux-next/drivers/parport/ieee1284_ops.c
Colin Ian King 0be883a0d7 parport: remove non-zero check on count 
The check for count appears to be incorrect since a non-zero count
check occurs a couple of statements earlier. Currently the check is
always false and the dev->port->irq != PARPORT_IRQ_NONE part of the
check is never tested and the if statement is dead-code. Fix this
by removing the check on count.

Note that this code is pre-git history, so I can't find a sha for
it.

Acked-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Addresses-Coverity: ("Logically dead code")
Link: https://lore.kernel.org/r/20210730100710.27405-1-colin.king@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-08-27 16:18:42 +02:00

894 lines
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// SPDX-License-Identifier: GPL-2.0
/* IEEE-1284 operations for parport.
*
* This file is for generic IEEE 1284 operations. The idea is that
* they are used by the low-level drivers. If they have a special way
* of doing something, they can provide their own routines (and put
* the function pointers in port->ops); if not, they can just use these
* as a fallback.
*
* Note: Make no assumptions about hardware or architecture in this file!
*
* Author: Tim Waugh <tim@cyberelk.demon.co.uk>
* Fixed AUTOFD polarity in ecp_forward_to_reverse(). Fred Barnes, 1999
* Software emulated EPP fixes, Fred Barnes, 04/2001.
*/
#include <linux/module.h>
#include <linux/parport.h>
#include <linux/delay.h>
#include <linux/sched/signal.h>
#include <linux/uaccess.h>
#undef DEBUG /* undef me for production */
#ifdef CONFIG_LP_CONSOLE
#undef DEBUG /* Don't want a garbled console */
#endif
/*** *
* One-way data transfer functions. *
* ***/
/* Compatibility mode. */
size_t parport_ieee1284_write_compat (struct parport *port,
const void *buffer, size_t len,
int flags)
{
int no_irq = 1;
ssize_t count = 0;
const unsigned char *addr = buffer;
unsigned char byte;
struct pardevice *dev = port->physport->cad;
unsigned char ctl = (PARPORT_CONTROL_SELECT
| PARPORT_CONTROL_INIT);
if (port->irq != PARPORT_IRQ_NONE) {
parport_enable_irq (port);
no_irq = 0;
}
port->physport->ieee1284.phase = IEEE1284_PH_FWD_DATA;
parport_write_control (port, ctl);
parport_data_forward (port);
while (count < len) {
unsigned long expire = jiffies + dev->timeout;
long wait = msecs_to_jiffies(10);
unsigned char mask = (PARPORT_STATUS_ERROR
| PARPORT_STATUS_BUSY);
unsigned char val = (PARPORT_STATUS_ERROR
| PARPORT_STATUS_BUSY);
/* Wait until the peripheral's ready */
do {
/* Is the peripheral ready yet? */
if (!parport_wait_peripheral (port, mask, val))
/* Skip the loop */
goto ready;
/* Is the peripheral upset? */
if ((parport_read_status (port) &
(PARPORT_STATUS_PAPEROUT |
PARPORT_STATUS_SELECT |
PARPORT_STATUS_ERROR))
!= (PARPORT_STATUS_SELECT |
PARPORT_STATUS_ERROR))
/* If nFault is asserted (i.e. no
* error) and PAPEROUT and SELECT are
* just red herrings, give the driver
* a chance to check it's happy with
* that before continuing. */
goto stop;
/* Have we run out of time? */
if (!time_before (jiffies, expire))
break;
/* Yield the port for a while. If this is the
first time around the loop, don't let go of
the port. This way, we find out if we have
our interrupt handler called. */
if (count && no_irq) {
parport_release (dev);
schedule_timeout_interruptible(wait);
parport_claim_or_block (dev);
}
else
/* We must have the device claimed here */
parport_wait_event (port, wait);
/* Is there a signal pending? */
if (signal_pending (current))
break;
/* Wait longer next time. */
wait *= 2;
} while (time_before (jiffies, expire));
if (signal_pending (current))
break;
pr_debug("%s: Timed out\n", port->name);
break;
ready:
/* Write the character to the data lines. */
byte = *addr++;
parport_write_data (port, byte);
udelay (1);
/* Pulse strobe. */
parport_write_control (port, ctl | PARPORT_CONTROL_STROBE);
udelay (1); /* strobe */
parport_write_control (port, ctl);
udelay (1); /* hold */
/* Assume the peripheral received it. */
count++;
/* Let another process run if it needs to. */
if (time_before (jiffies, expire))
if (!parport_yield_blocking (dev)
&& need_resched())
schedule ();
}
stop:
port->physport->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
return count;
}
/* Nibble mode. */
size_t parport_ieee1284_read_nibble (struct parport *port,
void *buffer, size_t len,
int flags)
{
#ifndef CONFIG_PARPORT_1284
return 0;
#else
unsigned char *buf = buffer;
int i;
unsigned char byte = 0;
len *= 2; /* in nibbles */
for (i=0; i < len; i++) {
unsigned char nibble;
/* Does the error line indicate end of data? */
if (((i & 1) == 0) &&
(parport_read_status(port) & PARPORT_STATUS_ERROR)) {
goto end_of_data;
}
/* Event 7: Set nAutoFd low. */
parport_frob_control (port,
PARPORT_CONTROL_AUTOFD,
PARPORT_CONTROL_AUTOFD);
/* Event 9: nAck goes low. */
port->ieee1284.phase = IEEE1284_PH_REV_DATA;
if (parport_wait_peripheral (port,
PARPORT_STATUS_ACK, 0)) {
/* Timeout -- no more data? */
pr_debug("%s: Nibble timeout at event 9 (%d bytes)\n",
port->name, i / 2);
parport_frob_control (port, PARPORT_CONTROL_AUTOFD, 0);
break;
}
/* Read a nibble. */
nibble = parport_read_status (port) >> 3;
nibble &= ~8;
if ((nibble & 0x10) == 0)
nibble |= 8;
nibble &= 0xf;
/* Event 10: Set nAutoFd high. */
parport_frob_control (port, PARPORT_CONTROL_AUTOFD, 0);
/* Event 11: nAck goes high. */
if (parport_wait_peripheral (port,
PARPORT_STATUS_ACK,
PARPORT_STATUS_ACK)) {
/* Timeout -- no more data? */
pr_debug("%s: Nibble timeout at event 11\n",
port->name);
break;
}
if (i & 1) {
/* Second nibble */
byte |= nibble << 4;
*buf++ = byte;
} else
byte = nibble;
}
if (i == len) {
/* Read the last nibble without checking data avail. */
if (parport_read_status (port) & PARPORT_STATUS_ERROR) {
end_of_data:
pr_debug("%s: No more nibble data (%d bytes)\n",
port->name, i / 2);
/* Go to reverse idle phase. */
parport_frob_control (port,
PARPORT_CONTROL_AUTOFD,
PARPORT_CONTROL_AUTOFD);
port->physport->ieee1284.phase = IEEE1284_PH_REV_IDLE;
}
else
port->physport->ieee1284.phase = IEEE1284_PH_HBUSY_DAVAIL;
}
return i/2;
#endif /* IEEE1284 support */
}
/* Byte mode. */
size_t parport_ieee1284_read_byte (struct parport *port,
void *buffer, size_t len,
int flags)
{
#ifndef CONFIG_PARPORT_1284
return 0;
#else
unsigned char *buf = buffer;
ssize_t count = 0;
for (count = 0; count < len; count++) {
unsigned char byte;
/* Data available? */
if (parport_read_status (port) & PARPORT_STATUS_ERROR) {
goto end_of_data;
}
/* Event 14: Place data bus in high impedance state. */
parport_data_reverse (port);
/* Event 7: Set nAutoFd low. */
parport_frob_control (port,
PARPORT_CONTROL_AUTOFD,
PARPORT_CONTROL_AUTOFD);
/* Event 9: nAck goes low. */
port->physport->ieee1284.phase = IEEE1284_PH_REV_DATA;
if (parport_wait_peripheral (port,
PARPORT_STATUS_ACK,
0)) {
/* Timeout -- no more data? */
parport_frob_control (port, PARPORT_CONTROL_AUTOFD,
0);
pr_debug("%s: Byte timeout at event 9\n", port->name);
break;
}
byte = parport_read_data (port);
*buf++ = byte;
/* Event 10: Set nAutoFd high */
parport_frob_control (port, PARPORT_CONTROL_AUTOFD, 0);
/* Event 11: nAck goes high. */
if (parport_wait_peripheral (port,
PARPORT_STATUS_ACK,
PARPORT_STATUS_ACK)) {
/* Timeout -- no more data? */
pr_debug("%s: Byte timeout at event 11\n", port->name);
break;
}
/* Event 16: Set nStrobe low. */
parport_frob_control (port,
PARPORT_CONTROL_STROBE,
PARPORT_CONTROL_STROBE);
udelay (5);
/* Event 17: Set nStrobe high. */
parport_frob_control (port, PARPORT_CONTROL_STROBE, 0);
}
if (count == len) {
/* Read the last byte without checking data avail. */
if (parport_read_status (port) & PARPORT_STATUS_ERROR) {
end_of_data:
pr_debug("%s: No more byte data (%zd bytes)\n",
port->name, count);
/* Go to reverse idle phase. */
parport_frob_control (port,
PARPORT_CONTROL_AUTOFD,
PARPORT_CONTROL_AUTOFD);
port->physport->ieee1284.phase = IEEE1284_PH_REV_IDLE;
}
else
port->physport->ieee1284.phase = IEEE1284_PH_HBUSY_DAVAIL;
}
return count;
#endif /* IEEE1284 support */
}
/*** *
* ECP Functions. *
* ***/
#ifdef CONFIG_PARPORT_1284
static inline
int ecp_forward_to_reverse (struct parport *port)
{
int retval;
/* Event 38: Set nAutoFd low */
parport_frob_control (port,
PARPORT_CONTROL_AUTOFD,
PARPORT_CONTROL_AUTOFD);
parport_data_reverse (port);
udelay (5);
/* Event 39: Set nInit low to initiate bus reversal */
parport_frob_control (port,
PARPORT_CONTROL_INIT,
0);
/* Event 40: PError goes low */
retval = parport_wait_peripheral (port,
PARPORT_STATUS_PAPEROUT, 0);
if (!retval) {
pr_debug("%s: ECP direction: reverse\n", port->name);
port->ieee1284.phase = IEEE1284_PH_REV_IDLE;
} else {
pr_debug("%s: ECP direction: failed to reverse\n", port->name);
port->ieee1284.phase = IEEE1284_PH_ECP_DIR_UNKNOWN;
}
return retval;
}
static inline
int ecp_reverse_to_forward (struct parport *port)
{
int retval;
/* Event 47: Set nInit high */
parport_frob_control (port,
PARPORT_CONTROL_INIT
| PARPORT_CONTROL_AUTOFD,
PARPORT_CONTROL_INIT
| PARPORT_CONTROL_AUTOFD);
/* Event 49: PError goes high */
retval = parport_wait_peripheral (port,
PARPORT_STATUS_PAPEROUT,
PARPORT_STATUS_PAPEROUT);
if (!retval) {
parport_data_forward (port);
pr_debug("%s: ECP direction: forward\n", port->name);
port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
} else {
pr_debug("%s: ECP direction: failed to switch forward\n",
port->name);
port->ieee1284.phase = IEEE1284_PH_ECP_DIR_UNKNOWN;
}
return retval;
}
#endif /* IEEE1284 support */
/* ECP mode, forward channel, data. */
size_t parport_ieee1284_ecp_write_data (struct parport *port,
const void *buffer, size_t len,
int flags)
{
#ifndef CONFIG_PARPORT_1284
return 0;
#else
const unsigned char *buf = buffer;
size_t written;
int retry;
port = port->physport;
if (port->ieee1284.phase != IEEE1284_PH_FWD_IDLE)
if (ecp_reverse_to_forward (port))
return 0;
port->ieee1284.phase = IEEE1284_PH_FWD_DATA;
/* HostAck high (data, not command) */
parport_frob_control (port,
PARPORT_CONTROL_AUTOFD
| PARPORT_CONTROL_STROBE
| PARPORT_CONTROL_INIT,
PARPORT_CONTROL_INIT);
for (written = 0; written < len; written++, buf++) {
unsigned long expire = jiffies + port->cad->timeout;
unsigned char byte;
byte = *buf;
try_again:
parport_write_data (port, byte);
parport_frob_control (port, PARPORT_CONTROL_STROBE,
PARPORT_CONTROL_STROBE);
udelay (5);
for (retry = 0; retry < 100; retry++) {
if (!parport_wait_peripheral (port,
PARPORT_STATUS_BUSY, 0))
goto success;
if (signal_pending (current)) {
parport_frob_control (port,
PARPORT_CONTROL_STROBE,
0);
break;
}
}
/* Time for Host Transfer Recovery (page 41 of IEEE1284) */
pr_debug("%s: ECP transfer stalled!\n", port->name);
parport_frob_control (port, PARPORT_CONTROL_INIT,
PARPORT_CONTROL_INIT);
udelay (50);
if (parport_read_status (port) & PARPORT_STATUS_PAPEROUT) {
/* It's buggered. */
parport_frob_control (port, PARPORT_CONTROL_INIT, 0);
break;
}
parport_frob_control (port, PARPORT_CONTROL_INIT, 0);
udelay (50);
if (!(parport_read_status (port) & PARPORT_STATUS_PAPEROUT))
break;
pr_debug("%s: Host transfer recovered\n", port->name);
if (time_after_eq (jiffies, expire)) break;
goto try_again;
success:
parport_frob_control (port, PARPORT_CONTROL_STROBE, 0);
udelay (5);
if (parport_wait_peripheral (port,
PARPORT_STATUS_BUSY,
PARPORT_STATUS_BUSY))
/* Peripheral hasn't accepted the data. */
break;
}
port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
return written;
#endif /* IEEE1284 support */
}
/* ECP mode, reverse channel, data. */
size_t parport_ieee1284_ecp_read_data (struct parport *port,
void *buffer, size_t len, int flags)
{
#ifndef CONFIG_PARPORT_1284
return 0;
#else
struct pardevice *dev = port->cad;
unsigned char *buf = buffer;
int rle_count = 0; /* shut gcc up */
unsigned char ctl;
int rle = 0;
ssize_t count = 0;
port = port->physport;
if (port->ieee1284.phase != IEEE1284_PH_REV_IDLE)
if (ecp_forward_to_reverse (port))
return 0;
port->ieee1284.phase = IEEE1284_PH_REV_DATA;
/* Set HostAck low to start accepting data. */
ctl = parport_read_control (port);
ctl &= ~(PARPORT_CONTROL_STROBE | PARPORT_CONTROL_INIT |
PARPORT_CONTROL_AUTOFD);
parport_write_control (port,
ctl | PARPORT_CONTROL_AUTOFD);
while (count < len) {
unsigned long expire = jiffies + dev->timeout;
unsigned char byte;
int command;
/* Event 43: Peripheral sets nAck low. It can take as
long as it wants. */
while (parport_wait_peripheral (port, PARPORT_STATUS_ACK, 0)) {
/* The peripheral hasn't given us data in
35ms. If we have data to give back to the
caller, do it now. */
if (count)
goto out;
/* If we've used up all the time we were allowed,
give up altogether. */
if (!time_before (jiffies, expire))
goto out;
/* Yield the port for a while. */
if (dev->port->irq != PARPORT_IRQ_NONE) {
parport_release (dev);
schedule_timeout_interruptible(msecs_to_jiffies(40));
parport_claim_or_block (dev);
}
else
/* We must have the device claimed here. */
parport_wait_event (port, msecs_to_jiffies(40));
/* Is there a signal pending? */
if (signal_pending (current))
goto out;
}
/* Is this a command? */
if (rle)
/* The last byte was a run-length count, so
this can't be as well. */
command = 0;
else
command = (parport_read_status (port) &
PARPORT_STATUS_BUSY) ? 1 : 0;
/* Read the data. */
byte = parport_read_data (port);
/* If this is a channel command, rather than an RLE
command or a normal data byte, don't accept it. */
if (command) {
if (byte & 0x80) {
pr_debug("%s: stopping short at channel command (%02x)\n",
port->name, byte);
goto out;
}
else if (port->ieee1284.mode != IEEE1284_MODE_ECPRLE)
pr_debug("%s: device illegally using RLE; accepting anyway\n",
port->name);
rle_count = byte + 1;
/* Are we allowed to read that many bytes? */
if (rle_count > (len - count)) {
pr_debug("%s: leaving %d RLE bytes for next time\n",
port->name, rle_count);
break;
}
rle = 1;
}
/* Event 44: Set HostAck high, acknowledging handshake. */
parport_write_control (port, ctl);
/* Event 45: The peripheral has 35ms to set nAck high. */
if (parport_wait_peripheral (port, PARPORT_STATUS_ACK,
PARPORT_STATUS_ACK)) {
/* It's gone wrong. Return what data we have
to the caller. */
pr_debug("ECP read timed out at 45\n");
if (command)
pr_warn("%s: command ignored (%02x)\n",
port->name, byte);
break;
}
/* Event 46: Set HostAck low and accept the data. */
parport_write_control (port,
ctl | PARPORT_CONTROL_AUTOFD);
/* If we just read a run-length count, fetch the data. */
if (command)
continue;
/* If this is the byte after a run-length count, decompress. */
if (rle) {
rle = 0;
memset (buf, byte, rle_count);
buf += rle_count;
count += rle_count;
pr_debug("%s: decompressed to %d bytes\n",
port->name, rle_count);
} else {
/* Normal data byte. */
*buf = byte;
buf++, count++;
}
}
out:
port->ieee1284.phase = IEEE1284_PH_REV_IDLE;
return count;
#endif /* IEEE1284 support */
}
/* ECP mode, forward channel, commands. */
size_t parport_ieee1284_ecp_write_addr (struct parport *port,
const void *buffer, size_t len,
int flags)
{
#ifndef CONFIG_PARPORT_1284
return 0;
#else
const unsigned char *buf = buffer;
size_t written;
int retry;
port = port->physport;
if (port->ieee1284.phase != IEEE1284_PH_FWD_IDLE)
if (ecp_reverse_to_forward (port))
return 0;
port->ieee1284.phase = IEEE1284_PH_FWD_DATA;
/* HostAck low (command, not data) */
parport_frob_control (port,
PARPORT_CONTROL_AUTOFD
| PARPORT_CONTROL_STROBE
| PARPORT_CONTROL_INIT,
PARPORT_CONTROL_AUTOFD
| PARPORT_CONTROL_INIT);
for (written = 0; written < len; written++, buf++) {
unsigned long expire = jiffies + port->cad->timeout;
unsigned char byte;
byte = *buf;
try_again:
parport_write_data (port, byte);
parport_frob_control (port, PARPORT_CONTROL_STROBE,
PARPORT_CONTROL_STROBE);
udelay (5);
for (retry = 0; retry < 100; retry++) {
if (!parport_wait_peripheral (port,
PARPORT_STATUS_BUSY, 0))
goto success;
if (signal_pending (current)) {
parport_frob_control (port,
PARPORT_CONTROL_STROBE,
0);
break;
}
}
/* Time for Host Transfer Recovery (page 41 of IEEE1284) */
pr_debug("%s: ECP transfer stalled!\n", port->name);
parport_frob_control (port, PARPORT_CONTROL_INIT,
PARPORT_CONTROL_INIT);
udelay (50);
if (parport_read_status (port) & PARPORT_STATUS_PAPEROUT) {
/* It's buggered. */
parport_frob_control (port, PARPORT_CONTROL_INIT, 0);
break;
}
parport_frob_control (port, PARPORT_CONTROL_INIT, 0);
udelay (50);
if (!(parport_read_status (port) & PARPORT_STATUS_PAPEROUT))
break;
pr_debug("%s: Host transfer recovered\n", port->name);
if (time_after_eq (jiffies, expire)) break;
goto try_again;
success:
parport_frob_control (port, PARPORT_CONTROL_STROBE, 0);
udelay (5);
if (parport_wait_peripheral (port,
PARPORT_STATUS_BUSY,
PARPORT_STATUS_BUSY))
/* Peripheral hasn't accepted the data. */
break;
}
port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
return written;
#endif /* IEEE1284 support */
}
/*** *
* EPP functions. *
* ***/
/* EPP mode, forward channel, data. */
size_t parport_ieee1284_epp_write_data (struct parport *port,
const void *buffer, size_t len,
int flags)
{
unsigned char *bp = (unsigned char *) buffer;
size_t ret = 0;
/* set EPP idle state (just to make sure) with strobe low */
parport_frob_control (port,
PARPORT_CONTROL_STROBE |
PARPORT_CONTROL_AUTOFD |
PARPORT_CONTROL_SELECT |
PARPORT_CONTROL_INIT,
PARPORT_CONTROL_STROBE |
PARPORT_CONTROL_INIT);
port->ops->data_forward (port);
for (; len > 0; len--, bp++) {
/* Event 62: Write data and set autofd low */
parport_write_data (port, *bp);
parport_frob_control (port, PARPORT_CONTROL_AUTOFD,
PARPORT_CONTROL_AUTOFD);
/* Event 58: wait for busy (nWait) to go high */
if (parport_poll_peripheral (port, PARPORT_STATUS_BUSY, 0, 10))
break;
/* Event 63: set nAutoFd (nDStrb) high */
parport_frob_control (port, PARPORT_CONTROL_AUTOFD, 0);
/* Event 60: wait for busy (nWait) to go low */
if (parport_poll_peripheral (port, PARPORT_STATUS_BUSY,
PARPORT_STATUS_BUSY, 5))
break;
ret++;
}
/* Event 61: set strobe (nWrite) high */
parport_frob_control (port, PARPORT_CONTROL_STROBE, 0);
return ret;
}
/* EPP mode, reverse channel, data. */
size_t parport_ieee1284_epp_read_data (struct parport *port,
void *buffer, size_t len,
int flags)
{
unsigned char *bp = (unsigned char *) buffer;
unsigned ret = 0;
/* set EPP idle state (just to make sure) with strobe high */
parport_frob_control (port,
PARPORT_CONTROL_STROBE |
PARPORT_CONTROL_AUTOFD |
PARPORT_CONTROL_SELECT |
PARPORT_CONTROL_INIT,
PARPORT_CONTROL_INIT);
port->ops->data_reverse (port);
for (; len > 0; len--, bp++) {
/* Event 67: set nAutoFd (nDStrb) low */
parport_frob_control (port,
PARPORT_CONTROL_AUTOFD,
PARPORT_CONTROL_AUTOFD);
/* Event 58: wait for Busy to go high */
if (parport_wait_peripheral (port, PARPORT_STATUS_BUSY, 0)) {
break;
}
*bp = parport_read_data (port);
/* Event 63: set nAutoFd (nDStrb) high */
parport_frob_control (port, PARPORT_CONTROL_AUTOFD, 0);
/* Event 60: wait for Busy to go low */
if (parport_poll_peripheral (port, PARPORT_STATUS_BUSY,
PARPORT_STATUS_BUSY, 5)) {
break;
}
ret++;
}
port->ops->data_forward (port);
return ret;
}
/* EPP mode, forward channel, addresses. */
size_t parport_ieee1284_epp_write_addr (struct parport *port,
const void *buffer, size_t len,
int flags)
{
unsigned char *bp = (unsigned char *) buffer;
size_t ret = 0;
/* set EPP idle state (just to make sure) with strobe low */
parport_frob_control (port,
PARPORT_CONTROL_STROBE |
PARPORT_CONTROL_AUTOFD |
PARPORT_CONTROL_SELECT |
PARPORT_CONTROL_INIT,
PARPORT_CONTROL_STROBE |
PARPORT_CONTROL_INIT);
port->ops->data_forward (port);
for (; len > 0; len--, bp++) {
/* Event 56: Write data and set nAStrb low. */
parport_write_data (port, *bp);
parport_frob_control (port, PARPORT_CONTROL_SELECT,
PARPORT_CONTROL_SELECT);
/* Event 58: wait for busy (nWait) to go high */
if (parport_poll_peripheral (port, PARPORT_STATUS_BUSY, 0, 10))
break;
/* Event 59: set nAStrb high */
parport_frob_control (port, PARPORT_CONTROL_SELECT, 0);
/* Event 60: wait for busy (nWait) to go low */
if (parport_poll_peripheral (port, PARPORT_STATUS_BUSY,
PARPORT_STATUS_BUSY, 5))
break;
ret++;
}
/* Event 61: set strobe (nWrite) high */
parport_frob_control (port, PARPORT_CONTROL_STROBE, 0);
return ret;
}
/* EPP mode, reverse channel, addresses. */
size_t parport_ieee1284_epp_read_addr (struct parport *port,
void *buffer, size_t len,
int flags)
{
unsigned char *bp = (unsigned char *) buffer;
unsigned ret = 0;
/* Set EPP idle state (just to make sure) with strobe high */
parport_frob_control (port,
PARPORT_CONTROL_STROBE |
PARPORT_CONTROL_AUTOFD |
PARPORT_CONTROL_SELECT |
PARPORT_CONTROL_INIT,
PARPORT_CONTROL_INIT);
port->ops->data_reverse (port);
for (; len > 0; len--, bp++) {
/* Event 64: set nSelectIn (nAStrb) low */
parport_frob_control (port, PARPORT_CONTROL_SELECT,
PARPORT_CONTROL_SELECT);
/* Event 58: wait for Busy to go high */
if (parport_wait_peripheral (port, PARPORT_STATUS_BUSY, 0)) {
break;
}
*bp = parport_read_data (port);
/* Event 59: set nSelectIn (nAStrb) high */
parport_frob_control (port, PARPORT_CONTROL_SELECT,
0);
/* Event 60: wait for Busy to go low */
if (parport_poll_peripheral (port, PARPORT_STATUS_BUSY,
PARPORT_STATUS_BUSY, 5))
break;
ret++;
}
port->ops->data_forward (port);
return ret;
}
EXPORT_SYMBOL(parport_ieee1284_ecp_write_data);
EXPORT_SYMBOL(parport_ieee1284_ecp_read_data);
EXPORT_SYMBOL(parport_ieee1284_ecp_write_addr);
EXPORT_SYMBOL(parport_ieee1284_write_compat);
EXPORT_SYMBOL(parport_ieee1284_read_nibble);
EXPORT_SYMBOL(parport_ieee1284_read_byte);
EXPORT_SYMBOL(parport_ieee1284_epp_write_data);
EXPORT_SYMBOL(parport_ieee1284_epp_read_data);
EXPORT_SYMBOL(parport_ieee1284_epp_write_addr);
EXPORT_SYMBOL(parport_ieee1284_epp_read_addr);
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