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linux-stable-rt/drivers/char/ftape/lowlevel/ftape-rw.c

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/*
* Copyright (C) 1993-1996 Bas Laarhoven,
* (C) 1996-1997 Claus-Justus Heine.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Source: /homes/cvs/ftape-stacked/ftape/lowlevel/ftape-rw.c,v $
* $Revision: 1.7 $
* $Date: 1997/10/28 14:26:49 $
*
* This file contains some common code for the segment read and
* segment write routines for the QIC-117 floppy-tape driver for
* Linux.
*/
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/ftape.h>
#include <linux/qic117.h>
#include "../lowlevel/ftape-tracing.h"
#include "../lowlevel/ftape-rw.h"
#include "../lowlevel/fdc-io.h"
#include "../lowlevel/ftape-init.h"
#include "../lowlevel/ftape-io.h"
#include "../lowlevel/ftape-ctl.h"
#include "../lowlevel/ftape-read.h"
#include "../lowlevel/ftape-ecc.h"
#include "../lowlevel/ftape-bsm.h"
/* Global vars.
*/
int ft_nr_buffers;
buffer_struct *ft_buffer[FT_MAX_NR_BUFFERS];
static volatile int ft_head;
static volatile int ft_tail; /* not volatile but need same type as head */
int fdc_setup_error;
location_record ft_location = {-1, 0};
volatile int ftape_tape_running;
/* Local vars.
*/
static int overrun_count_offset;
static int inhibit_correction;
/* maxmimal allowed overshoot when fast seeking
*/
#define OVERSHOOT_LIMIT 10
/* Increment cyclic buffer nr.
*/
buffer_struct *ftape_next_buffer(ft_buffer_queue_t pos)
{
switch (pos) {
case ft_queue_head:
if (++ft_head >= ft_nr_buffers) {
ft_head = 0;
}
return ft_buffer[ft_head];
case ft_queue_tail:
if (++ft_tail >= ft_nr_buffers) {
ft_tail = 0;
}
return ft_buffer[ft_tail];
default:
return NULL;
}
}
int ftape_buffer_id(ft_buffer_queue_t pos)
{
switch(pos) {
case ft_queue_head: return ft_head;
case ft_queue_tail: return ft_tail;
default: return -1;
}
}
buffer_struct *ftape_get_buffer(ft_buffer_queue_t pos)
{
switch(pos) {
case ft_queue_head: return ft_buffer[ft_head];
case ft_queue_tail: return ft_buffer[ft_tail];
default: return NULL;
}
}
void ftape_reset_buffer(void)
{
ft_head = ft_tail = 0;
}
buffer_state_enum ftape_set_state(buffer_state_enum new_state)
{
buffer_state_enum old_state = ft_driver_state;
ft_driver_state = new_state;
return old_state;
}
/* Calculate Floppy Disk Controller and DMA parameters for a segment.
* head: selects buffer struct in array.
* offset: number of physical sectors to skip (including bad ones).
* count: number of physical sectors to handle (including bad ones).
*/
static int setup_segment(buffer_struct * buff,
int segment_id,
unsigned int sector_offset,
unsigned int sector_count,
int retry)
{
SectorMap offset_mask;
SectorMap mask;
TRACE_FUN(ft_t_any);
buff->segment_id = segment_id;
buff->sector_offset = sector_offset;
buff->remaining = sector_count;
buff->head = segment_id / ftape_segments_per_head;
buff->cyl = (segment_id % ftape_segments_per_head) / ftape_segments_per_cylinder;
buff->sect = (segment_id % ftape_segments_per_cylinder) * FT_SECTORS_PER_SEGMENT + 1;
buff->deleted = 0;
offset_mask = (1 << buff->sector_offset) - 1;
mask = ftape_get_bad_sector_entry(segment_id) & offset_mask;
while (mask) {
if (mask & 1) {
offset_mask >>= 1; /* don't count bad sector */
}
mask >>= 1;
}
buff->data_offset = count_ones(offset_mask); /* good sectors to skip */
buff->ptr = buff->address + buff->data_offset * FT_SECTOR_SIZE;
TRACE(ft_t_flow, "data offset = %d sectors", buff->data_offset);
if (retry) {
buff->soft_error_map &= offset_mask; /* keep skipped part */
} else {
buff->hard_error_map = buff->soft_error_map = 0;
}
buff->bad_sector_map = ftape_get_bad_sector_entry(buff->segment_id);
if (buff->bad_sector_map != 0) {
TRACE(ft_t_noise, "segment: %d, bad sector map: %08lx",
buff->segment_id, (long)buff->bad_sector_map);
} else {
TRACE(ft_t_flow, "segment: %d", buff->segment_id);
}
if (buff->sector_offset > 0) {
buff->bad_sector_map >>= buff->sector_offset;
}
if (buff->sector_offset != 0 || buff->remaining != FT_SECTORS_PER_SEGMENT) {
TRACE(ft_t_flow, "sector offset = %d, count = %d",
buff->sector_offset, buff->remaining);
}
/* Segments with 3 or less sectors are not written with valid
* data because there is no space left for the ecc. The
* data written is whatever happens to be in the buffer.
* Reading such a segment will return a zero byte-count.
* To allow us to read/write segments with all bad sectors
* we fake one readable sector in the segment. This
* prevents having to handle these segments in a very
* special way. It is not important if the reading of this
* bad sector fails or not (the data is ignored). It is
* only read to keep the driver running.
*
* The QIC-40/80 spec. has no information on how to handle
* this case, so this is my interpretation.
*/
if (buff->bad_sector_map == EMPTY_SEGMENT) {
TRACE(ft_t_flow, "empty segment %d, fake first sector good",
buff->segment_id);
if (buff->ptr != buff->address) {
TRACE(ft_t_bug, "This is a bug: %p/%p",
buff->ptr, buff->address);
}
buff->bad_sector_map = FAKE_SEGMENT;
}
fdc_setup_error = 0;
buff->next_segment = segment_id + 1;
TRACE_EXIT 0;
}
/* Calculate Floppy Disk Controller and DMA parameters for a new segment.
*/
int ftape_setup_new_segment(buffer_struct * buff, int segment_id, int skip)
{
int result = 0;
static int old_segment_id = -1;
static buffer_state_enum old_ft_driver_state = idle;
int retry = 0;
unsigned offset = 0;
int count = FT_SECTORS_PER_SEGMENT;
TRACE_FUN(ft_t_flow);
TRACE(ft_t_flow, "%s segment %d (old = %d)",
(ft_driver_state == reading || ft_driver_state == verifying)
? "reading" : "writing",
segment_id, old_segment_id);
if (ft_driver_state != old_ft_driver_state) { /* when verifying */
old_segment_id = -1;
old_ft_driver_state = ft_driver_state;
}
if (segment_id == old_segment_id) {
++buff->retry;
++ft_history.retries;
TRACE(ft_t_flow, "setting up for retry nr %d", buff->retry);
retry = 1;
if (skip && buff->skip > 0) { /* allow skip on retry */
offset = buff->skip;
count -= offset;
TRACE(ft_t_flow, "skipping %d sectors", offset);
}
} else {
buff->retry = 0;
buff->skip = 0;
old_segment_id = segment_id;
}
result = setup_segment(buff, segment_id, offset, count, retry);
TRACE_EXIT result;
}
/* Determine size of next cluster of good sectors.
*/
int ftape_calc_next_cluster(buffer_struct * buff)
{
/* Skip bad sectors.
*/
while (buff->remaining > 0 && (buff->bad_sector_map & 1) != 0) {
buff->bad_sector_map >>= 1;
++buff->sector_offset;
--buff->remaining;
}
/* Find next cluster of good sectors
*/
if (buff->bad_sector_map == 0) { /* speed up */
buff->sector_count = buff->remaining;
} else {
SectorMap map = buff->bad_sector_map;
buff->sector_count = 0;
while (buff->sector_count < buff->remaining && (map & 1) == 0) {
++buff->sector_count;
map >>= 1;
}
}
return buff->sector_count;
}
/* if just passed the last segment on a track, wait for BOT
* or EOT mark.
*/
int ftape_handle_logical_eot(void)
{
TRACE_FUN(ft_t_flow);
if (ft_runner_status == logical_eot) {
int status;
TRACE(ft_t_noise, "tape at logical EOT");
TRACE_CATCH(ftape_ready_wait(ftape_timeout.seek, &status),);
if ((status & (QIC_STATUS_AT_BOT | QIC_STATUS_AT_EOT)) == 0) {
TRACE_ABORT(-EIO, ft_t_err, "eot/bot not reached");
}
ft_runner_status = end_of_tape;
}
if (ft_runner_status == end_of_tape) {
TRACE(ft_t_noise, "runner stopped because of logical EOT");
ft_runner_status = idle;
}
TRACE_EXIT 0;
}
static int check_bot_eot(int status)
{
TRACE_FUN(ft_t_flow);
if (status & (QIC_STATUS_AT_BOT | QIC_STATUS_AT_EOT)) {
ft_location.bot = ((ft_location.track & 1) == 0 ?
(status & QIC_STATUS_AT_BOT) != 0:
(status & QIC_STATUS_AT_EOT) != 0);
ft_location.eot = !ft_location.bot;
ft_location.segment = (ft_location.track +
(ft_location.bot ? 0 : 1)) * ft_segments_per_track - 1;
ft_location.sector = -1;
ft_location.known = 1;
TRACE(ft_t_flow, "tape at logical %s",
ft_location.bot ? "bot" : "eot");
TRACE(ft_t_flow, "segment = %d", ft_location.segment);
} else {
ft_location.known = 0;
}
TRACE_EXIT ft_location.known;
}
/* Read Id of first sector passing tape head.
*/
static int ftape_read_id(void)
{
int status;
__u8 out[2];
TRACE_FUN(ft_t_any);
/* Assume tape is running on entry, be able to handle
* situation where it stopped or is stopping.
*/
ft_location.known = 0; /* default is location not known */
out[0] = FDC_READID;
out[1] = ft_drive_sel;
TRACE_CATCH(fdc_command(out, 2),);
switch (fdc_interrupt_wait(20 * FT_SECOND)) {
case 0:
if (fdc_sect == 0) {
if (ftape_report_drive_status(&status) >= 0 &&
(status & QIC_STATUS_READY)) {
ftape_tape_running = 0;
TRACE(ft_t_flow, "tape has stopped");
check_bot_eot(status);
}
} else {
ft_location.known = 1;
ft_location.segment = (ftape_segments_per_head
* fdc_head
+ ftape_segments_per_cylinder
* fdc_cyl
+ (fdc_sect - 1)
/ FT_SECTORS_PER_SEGMENT);
ft_location.sector = ((fdc_sect - 1)
% FT_SECTORS_PER_SEGMENT);
ft_location.eot = ft_location.bot = 0;
}
break;
case -ETIME:
/* Didn't find id on tape, must be near end: Wait
* until stopped.
*/
if (ftape_ready_wait(FT_FOREVER, &status) >= 0) {
ftape_tape_running = 0;
TRACE(ft_t_flow, "tape has stopped");
check_bot_eot(status);
}
break;
default:
/* Interrupted or otherwise failing
* fdc_interrupt_wait()
*/
TRACE(ft_t_err, "fdc_interrupt_wait failed");
break;
}
if (!ft_location.known) {
TRACE_ABORT(-EIO, ft_t_flow, "no id found");
}
if (ft_location.sector == 0) {
TRACE(ft_t_flow, "passing segment %d/%d",
ft_location.segment, ft_location.sector);
} else {
TRACE(ft_t_fdc_dma, "passing segment %d/%d",
ft_location.segment, ft_location.sector);
}
TRACE_EXIT 0;
}
static int logical_forward(void)
{
ftape_tape_running = 1;
return ftape_command(QIC_LOGICAL_FORWARD);
}
int ftape_stop_tape(int *pstatus)
{
int retry = 0;
int result;
TRACE_FUN(ft_t_flow);
do {
result = ftape_command_wait(QIC_STOP_TAPE,
ftape_timeout.stop, pstatus);
if (result == 0) {
if ((*pstatus & QIC_STATUS_READY) == 0) {
result = -EIO;
} else {
ftape_tape_running = 0;
}
}
} while (result < 0 && ++retry <= 3);
if (result < 0) {
TRACE(ft_t_err, "failed ! (fatal)");
}
TRACE_EXIT result;
}
int ftape_dumb_stop(void)
{
int result;
int status;
TRACE_FUN(ft_t_flow);
/* Abort current fdc operation if it's busy (probably read
* or write operation pending) with a reset.
*/
if (fdc_ready_wait(100 /* usec */) < 0) {
TRACE(ft_t_noise, "aborting fdc operation");
fdc_reset();
}
/* Reading id's after the last segment on a track may fail
* but eventually the drive will become ready (logical eot).
*/
result = ftape_report_drive_status(&status);
ft_location.known = 0;
do {
if (result == 0 && status & QIC_STATUS_READY) {
/* Tape is not running any more.
*/
TRACE(ft_t_noise, "tape already halted");
check_bot_eot(status);
ftape_tape_running = 0;
} else if (ftape_tape_running) {
/* Tape is (was) still moving.
*/
#ifdef TESTING
ftape_read_id();
#endif
result = ftape_stop_tape(&status);
} else {
/* Tape not yet ready but stopped.
*/
result = ftape_ready_wait(ftape_timeout.pause,&status);
}
} while (ftape_tape_running
&& !(sigtestsetmask(&current->pending.signal, _NEVER_BLOCK)));
#ifndef TESTING
ft_location.known = 0;
#endif
if (ft_runner_status == aborting || ft_runner_status == do_abort) {
ft_runner_status = idle;
}
TRACE_EXIT result;
}
/* Wait until runner has finished tail buffer.
*
*/
int ftape_wait_segment(buffer_state_enum state)
{
int status;
int result = 0;
TRACE_FUN(ft_t_flow);
while (ft_buffer[ft_tail]->status == state) {
TRACE(ft_t_flow, "state: %d", ft_buffer[ft_tail]->status);
/* First buffer still being worked on, wait up to timeout.
*
* Note: we check two times for being killed. 50
* seconds are quite long. Note that
* fdc_interrupt_wait() is not killable by any
* means. ftape_read_segment() wants us to return
* -EINTR in case of a signal.
*/
FT_SIGNAL_EXIT(_DONT_BLOCK);
result = fdc_interrupt_wait(50 * FT_SECOND);
FT_SIGNAL_EXIT(_DONT_BLOCK);
if (result < 0) {
TRACE_ABORT(result,
ft_t_err, "fdc_interrupt_wait failed");
}
if (fdc_setup_error) {
/* recover... FIXME */
TRACE_ABORT(-EIO, ft_t_err, "setup error");
}
}
if (ft_buffer[ft_tail]->status != error) {
TRACE_EXIT 0;
}
TRACE_CATCH(ftape_report_drive_status(&status),);
TRACE(ft_t_noise, "ftape_report_drive_status: 0x%02x", status);
if ((status & QIC_STATUS_READY) &&
(status & QIC_STATUS_ERROR)) {
unsigned int error;
qic117_cmd_t command;
/* Report and clear error state.
* In case the drive can't operate at the selected
* rate, select the next lower data rate.
*/
ftape_report_error(&error, &command, 1);
if (error == 31 && command == QIC_LOGICAL_FORWARD) {
/* drive does not accept this data rate */
if (ft_data_rate > 250) {
TRACE(ft_t_info,
"Probable data rate conflict");
TRACE(ft_t_info,
"Lowering data rate to %d Kbps",
ft_data_rate / 2);
ftape_half_data_rate();
if (ft_buffer[ft_tail]->retry > 0) {
/* give it a chance */
--ft_buffer[ft_tail]->retry;
}
} else {
/* no rate is accepted... */
TRACE(ft_t_err, "We're dead :(");
}
} else {
TRACE(ft_t_err, "Unknown error");
}
TRACE_EXIT -EIO; /* g.p. error */
}
TRACE_EXIT 0;
}
/* forward */ static int seek_forward(int segment_id, int fast);
static int fast_seek(int count, int reverse)
{
int result = 0;
int status;
TRACE_FUN(ft_t_flow);
if (count > 0) {
/* If positioned at begin or end of tape, fast seeking needs
* special treatment.
* Starting from logical bot needs a (slow) seek to the first
* segment before the high speed seek. Most drives do this
* automatically but some older don't, so we treat them
* all the same.
* Starting from logical eot is even more difficult because
* we cannot (slow) reverse seek to the last segment.
* TO BE IMPLEMENTED.
*/
inhibit_correction = 0;
if (ft_location.known &&
((ft_location.bot && !reverse) ||
(ft_location.eot && reverse))) {
if (!reverse) {
/* (slow) skip to first segment on a track
*/
seek_forward(ft_location.track * ft_segments_per_track, 0);
--count;
} else {
/* When seeking backwards from
* end-of-tape the number of erased
* gaps found seems to be higher than
* expected. Therefor the drive must
* skip some more segments than
* calculated, but we don't know how
* many. Thus we will prevent the
* re-calculation of offset and
* overshoot when seeking backwards.
*/
inhibit_correction = 1;
count += 3; /* best guess */
}
}
} else {
TRACE(ft_t_flow, "warning: zero or negative count: %d", count);
}
if (count > 0) {
int i;
int nibbles = count > 255 ? 3 : 2;
if (count > 4095) {
TRACE(ft_t_noise, "skipping clipped at 4095 segment");
count = 4095;
}
/* Issue this tape command first. */
if (!reverse) {
TRACE(ft_t_noise, "skipping %d segment(s)", count);
result = ftape_command(nibbles == 3 ?
QIC_SKIP_EXTENDED_FORWARD : QIC_SKIP_FORWARD);
} else {
TRACE(ft_t_noise, "backing up %d segment(s)", count);
result = ftape_command(nibbles == 3 ?
QIC_SKIP_EXTENDED_REVERSE : QIC_SKIP_REVERSE);
}
if (result < 0) {
TRACE(ft_t_noise, "Skip command failed");
} else {
--count; /* 0 means one gap etc. */
for (i = 0; i < nibbles; ++i) {
if (result >= 0) {
result = ftape_parameter(count & 15);
count /= 16;
}
}
result = ftape_ready_wait(ftape_timeout.rewind, &status);
if (result >= 0) {
ftape_tape_running = 0;
}
}
}
TRACE_EXIT result;
}
static int validate(int id)
{
/* Check to see if position found is off-track as reported
* once. Because all tracks in one direction lie next to
* each other, if off-track the error will be approximately
* 2 * ft_segments_per_track.
*/
if (ft_location.track == -1) {
return 1; /* unforseen situation, don't generate error */
} else {
/* Use margin of ft_segments_per_track on both sides
* because ftape needs some margin and the error we're
* looking for is much larger !
*/
int lo = (ft_location.track - 1) * ft_segments_per_track;
int hi = (ft_location.track + 2) * ft_segments_per_track;
return (id >= lo && id < hi);
}
}
static int seek_forward(int segment_id, int fast)
{
int failures = 0;
int count;
static int margin = 1; /* fixed: stop this before target */
static int overshoot = 1;
static int min_count = 8;
int expected = -1;
int target = segment_id - margin;
int fast_seeking;
int prev_segment = ft_location.segment;
TRACE_FUN(ft_t_flow);
if (!ft_location.known) {
TRACE_ABORT(-EIO, ft_t_err,
"fatal: cannot seek from unknown location");
}
if (!validate(segment_id)) {
ftape_sleep(1 * FT_SECOND);
ft_failure = 1;
TRACE_ABORT(-EIO, ft_t_err,
"fatal: head off track (bad hardware?)");
}
TRACE(ft_t_noise, "from %d/%d to %d/0 - %d",
ft_location.segment, ft_location.sector,segment_id,margin);
count = target - ft_location.segment - overshoot;
fast_seeking = (fast &&
count > (min_count + (ft_location.bot ? 1 : 0)));
if (fast_seeking) {
TRACE(ft_t_noise, "fast skipping %d segments", count);
expected = segment_id - margin;
fast_seek(count, 0);
}
if (!ftape_tape_running) {
logical_forward();
}
while (ft_location.segment < segment_id) {
/* This requires at least one sector in a (bad) segment to
* have a valid and readable sector id !
* It looks like this is not guaranteed, so we must try
* to find a way to skip an EMPTY_SEGMENT. !!! FIXME !!!
*/
if (ftape_read_id() < 0 || !ft_location.known ||
sigtestsetmask(&current->pending.signal, _DONT_BLOCK)) {
ft_location.known = 0;
if (!ftape_tape_running ||
++failures > FT_SECTORS_PER_SEGMENT) {
TRACE_ABORT(-EIO, ft_t_err,
"read_id failed completely");
}
FT_SIGNAL_EXIT(_DONT_BLOCK);
TRACE(ft_t_flow, "read_id failed, retry (%d)",
failures);
continue;
}
if (fast_seeking) {
TRACE(ft_t_noise, "ended at %d/%d (%d,%d)",
ft_location.segment, ft_location.sector,
overshoot, inhibit_correction);
if (!inhibit_correction &&
(ft_location.segment < expected ||
ft_location.segment > expected + margin)) {
int error = ft_location.segment - expected;
TRACE(ft_t_noise,
"adjusting overshoot from %d to %d",
overshoot, overshoot + error);
overshoot += error;
/* All overshoots have the same
* direction, so it should never
* become negative, but who knows.
*/
if (overshoot < -5 ||
overshoot > OVERSHOOT_LIMIT) {
if (overshoot < 0) {
/* keep sane value */
overshoot = -5;
} else {
/* keep sane value */
overshoot = OVERSHOOT_LIMIT;
}
TRACE(ft_t_noise,
"clipped overshoot to %d",
overshoot);
}
}
fast_seeking = 0;
}
if (ft_location.known) {
if (ft_location.segment > prev_segment + 1) {
TRACE(ft_t_noise,
"missed segment %d while skipping",
prev_segment + 1);
}
prev_segment = ft_location.segment;
}
}
if (ft_location.segment > segment_id) {
TRACE_ABORT(-EIO,
ft_t_noise, "failed: skip ended at segment %d/%d",
ft_location.segment, ft_location.sector);
}
TRACE_EXIT 0;
}
static int skip_reverse(int segment_id, int *pstatus)
{
int failures = 0;
static int overshoot = 1;
static int min_rewind = 2; /* 1 + overshoot */
static const int margin = 1; /* stop this before target */
int expected = 0;
int count = 1;
int short_seek;
int target = segment_id - margin;
TRACE_FUN(ft_t_flow);
if (ft_location.known && !validate(segment_id)) {
ftape_sleep(1 * FT_SECOND);
ft_failure = 1;
TRACE_ABORT(-EIO, ft_t_err,
"fatal: head off track (bad hardware?)");
}
do {
if (!ft_location.known) {
TRACE(ft_t_warn, "warning: location not known");
}
TRACE(ft_t_noise, "from %d/%d to %d/0 - %d",
ft_location.segment, ft_location.sector,
segment_id, margin);
/* min_rewind == 1 + overshoot_when_doing_minimum_rewind
* overshoot == overshoot_when_doing_larger_rewind
* Initially min_rewind == 1 + overshoot, optimization
* of both values will be done separately.
* overshoot and min_rewind can be negative as both are
* sums of three components:
* any_overshoot == rewind_overshoot -
* stop_overshoot -
* start_overshoot
*/
if (ft_location.segment - target - (min_rewind - 1) < 1) {
short_seek = 1;
} else {
count = ft_location.segment - target - overshoot;
short_seek = (count < 1);
}
if (short_seek) {
count = 1; /* do shortest rewind */
expected = ft_location.segment - min_rewind;
if (expected/ft_segments_per_track != ft_location.track) {
expected = (ft_location.track *
ft_segments_per_track);
}
} else {
expected = target;
}
fast_seek(count, 1);
logical_forward();
if (ftape_read_id() < 0 || !ft_location.known ||
(sigtestsetmask(&current->pending.signal, _DONT_BLOCK))) {
if ((!ftape_tape_running && !ft_location.known) ||
++failures > FT_SECTORS_PER_SEGMENT) {
TRACE_ABORT(-EIO, ft_t_err,
"read_id failed completely");
}
FT_SIGNAL_EXIT(_DONT_BLOCK);
TRACE_CATCH(ftape_report_drive_status(pstatus),);
TRACE(ft_t_noise, "ftape_read_id failed, retry (%d)",
failures);
continue;
}
TRACE(ft_t_noise, "ended at %d/%d (%d,%d,%d)",
ft_location.segment, ft_location.sector,
min_rewind, overshoot, inhibit_correction);
if (!inhibit_correction &&
(ft_location.segment < expected ||
ft_location.segment > expected + margin)) {
int error = expected - ft_location.segment;
if (short_seek) {
TRACE(ft_t_noise,
"adjusting min_rewind from %d to %d",
min_rewind, min_rewind + error);
min_rewind += error;
if (min_rewind < -5) {
/* is this right ? FIXME ! */
/* keep sane value */
min_rewind = -5;
TRACE(ft_t_noise,
"clipped min_rewind to %d",
min_rewind);
}
} else {
TRACE(ft_t_noise,
"adjusting overshoot from %d to %d",
overshoot, overshoot + error);
overshoot += error;
if (overshoot < -5 ||
overshoot > OVERSHOOT_LIMIT) {
if (overshoot < 0) {
/* keep sane value */
overshoot = -5;
} else {
/* keep sane value */
overshoot = OVERSHOOT_LIMIT;
}
TRACE(ft_t_noise,
"clipped overshoot to %d",
overshoot);
}
}
}
} while (ft_location.segment > segment_id);
if (ft_location.known) {
TRACE(ft_t_noise, "current location: %d/%d",
ft_location.segment, ft_location.sector);
}
TRACE_EXIT 0;
}
static int determine_position(void)
{
int retry = 0;
int status;
int result;
TRACE_FUN(ft_t_flow);
if (!ftape_tape_running) {
/* This should only happen if tape is stopped by isr.
*/
TRACE(ft_t_flow, "waiting for tape stop");
if (ftape_ready_wait(ftape_timeout.pause, &status) < 0) {
TRACE(ft_t_flow, "drive still running (fatal)");
ftape_tape_running = 1; /* ? */
}
} else {
ftape_report_drive_status(&status);
}
if (status & QIC_STATUS_READY) {
/* Drive must be ready to check error state !
*/
TRACE(ft_t_flow, "drive is ready");
if (status & QIC_STATUS_ERROR) {
unsigned int error;
qic117_cmd_t command;
/* Report and clear error state, try to continue.
*/
TRACE(ft_t_flow, "error status set");
ftape_report_error(&error, &command, 1);
ftape_ready_wait(ftape_timeout.reset, &status);
ftape_tape_running = 0; /* ? */
}
if (check_bot_eot(status)) {
if (ft_location.bot) {
if ((status & QIC_STATUS_READY) == 0) {
/* tape moving away from
* bot/eot, let's see if we
* can catch up with the first
* segment on this track.
*/
} else {
TRACE(ft_t_flow,
"start tape from logical bot");
logical_forward(); /* start moving */
}
} else {
if ((status & QIC_STATUS_READY) == 0) {
TRACE(ft_t_noise, "waiting for logical end of track");
result = ftape_ready_wait(ftape_timeout.reset, &status);
/* error handling needed ? */
} else {
TRACE(ft_t_noise,
"tape at logical end of track");
}
}
} else {
TRACE(ft_t_flow, "start tape");
logical_forward(); /* start moving */
ft_location.known = 0; /* not cleared by logical forward ! */
}
}
/* tape should be moving now, start reading id's
*/
while (!ft_location.known &&
retry++ < FT_SECTORS_PER_SEGMENT &&
(result = ftape_read_id()) < 0) {
TRACE(ft_t_flow, "location unknown");
/* exit on signal
*/
FT_SIGNAL_EXIT(_DONT_BLOCK);
/* read-id somehow failed, tape may
* have reached end or some other
* error happened.
*/
TRACE(ft_t_flow, "read-id failed");
TRACE_CATCH(ftape_report_drive_status(&status),);
TRACE(ft_t_err, "ftape_report_drive_status: 0x%02x", status);
if (status & QIC_STATUS_READY) {
ftape_tape_running = 0;
TRACE(ft_t_noise, "tape stopped for unknown reason! "
"status = 0x%02x", status);
if (status & QIC_STATUS_ERROR ||
!check_bot_eot(status)) {
/* oops, tape stopped but not at end!
*/
TRACE_EXIT -EIO;
}
}
}
TRACE(ft_t_flow,
"tape is positioned at segment %d", ft_location.segment);
TRACE_EXIT ft_location.known ? 0 : -EIO;
}
/* Get the tape running and position it just before the
* requested segment.
* Seek tape-track and reposition as needed.
*/
int ftape_start_tape(int segment_id, int sector_offset)
{
int track = segment_id / ft_segments_per_track;
int result = -EIO;
int status;
static int last_segment = -1;
static int bad_bus_timing = 0;
/* number of segments passing the head between starting the tape
* and being able to access the first sector.
*/
static int start_offset = 1;
int retry;
TRACE_FUN(ft_t_flow);
/* If sector_offset > 0, seek into wanted segment instead of
* into previous.
* This allows error recovery if a part of the segment is bad
* (erased) causing the tape drive to generate an index pulse
* thus causing a no-data error before the requested sector
* is reached.
*/
ftape_tape_running = 0;
TRACE(ft_t_noise, "target segment: %d/%d%s", segment_id, sector_offset,
ft_buffer[ft_head]->retry > 0 ? " retry" : "");
if (ft_buffer[ft_head]->retry > 0) { /* this is a retry */
int dist = segment_id - last_segment;
if ((int)ft_history.overrun_errors < overrun_count_offset) {
overrun_count_offset = ft_history.overrun_errors;
} else if (dist < 0 || dist > 50) {
overrun_count_offset = ft_history.overrun_errors;
} else if ((ft_history.overrun_errors -
overrun_count_offset) >= 8) {
if (ftape_increase_threshold() >= 0) {
--ft_buffer[ft_head]->retry;
overrun_count_offset =
ft_history.overrun_errors;
TRACE(ft_t_warn, "increased threshold because "
"of excessive overrun errors");
} else if (!bad_bus_timing && ft_data_rate >= 1000) {
ftape_half_data_rate();
--ft_buffer[ft_head]->retry;
bad_bus_timing = 1;
overrun_count_offset =
ft_history.overrun_errors;
TRACE(ft_t_warn, "reduced datarate because "
"of excessive overrun errors");
}
}
}
last_segment = segment_id;
if (ft_location.track != track ||
(ftape_might_be_off_track && ft_buffer[ft_head]->retry== 0)) {
/* current track unknown or not equal to destination
*/
ftape_ready_wait(ftape_timeout.seek, &status);
ftape_seek_head_to_track(track);
/* overrun_count_offset = ft_history.overrun_errors; */
}
result = -EIO;
retry = 0;
while (result < 0 &&
retry++ <= 5 &&
!ft_failure &&
!(sigtestsetmask(&current->pending.signal, _DONT_BLOCK))) {
if (retry && start_offset < 5) {
start_offset ++;
}
/* Check if we are able to catch the requested
* segment in time.
*/
if ((ft_location.known || (determine_position() == 0)) &&
ft_location.segment >=
(segment_id -
((ftape_tape_running || ft_location.bot)
? 0 : start_offset))) {
/* Too far ahead (in or past target segment).
*/
if (ftape_tape_running) {
if ((result = ftape_stop_tape(&status)) < 0) {
TRACE(ft_t_err,
"stop tape failed with code %d",
result);
break;
}
TRACE(ft_t_noise, "tape stopped");
ftape_tape_running = 0;
}
TRACE(ft_t_noise, "repositioning");
++ft_history.rewinds;
if (segment_id % ft_segments_per_track < start_offset){
TRACE(ft_t_noise, "end of track condition\n"
KERN_INFO "segment_id : %d\n"
KERN_INFO "ft_segments_per_track: %d\n"
KERN_INFO "start_offset : %d",
segment_id, ft_segments_per_track,
start_offset);
/* If seeking to first segments on
* track better do a complete rewind
* to logical begin of track to get a
* more steady tape motion.
*/
result = ftape_command_wait(
(ft_location.track & 1)
? QIC_PHYSICAL_FORWARD
: QIC_PHYSICAL_REVERSE,
ftape_timeout.rewind, &status);
check_bot_eot(status); /* update location */
} else {
result= skip_reverse(segment_id - start_offset,
&status);
}
}
if (!ft_location.known) {
TRACE(ft_t_bug, "panic: location not known");
result = -EIO;
continue; /* while() will check for failure */
}
TRACE(ft_t_noise, "current segment: %d/%d",
ft_location.segment, ft_location.sector);
/* We're on the right track somewhere before the
* wanted segment. Start tape movement if needed and
* skip to just before or inside the requested
* segment. Keep tape running.
*/
result = 0;
if (ft_location.segment <
(segment_id - ((ftape_tape_running || ft_location.bot)
? 0 : start_offset))) {
if (sector_offset > 0) {
result = seek_forward(segment_id,
retry <= 3);
} else {
result = seek_forward(segment_id - 1,
retry <= 3);
}
}
if (result == 0 &&
ft_location.segment !=
(segment_id - (sector_offset > 0 ? 0 : 1))) {
result = -EIO;
}
}
if (result < 0) {
TRACE(ft_t_err, "failed to reposition");
} else {
ft_runner_status = running;
}
TRACE_EXIT result;
}
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