patch-2.1.66 linux/drivers/char/ftape/lowlevel/ftape-rw.c
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- Lines: 1092
- Date:
Tue Nov 25 14:45:27 1997
- Orig file:
v2.1.65/linux/drivers/char/ftape/lowlevel/ftape-rw.c
- Orig date:
Wed Dec 31 16:00:00 1969
diff -u --recursive --new-file v2.1.65/linux/drivers/char/ftape/lowlevel/ftape-rw.c linux/drivers/char/ftape/lowlevel/ftape-rw.c
@@ -0,0 +1,1091 @@
+/*
+ * 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 = 0;
+buffer_struct *ft_buffer[FT_MAX_NR_BUFFERS] = {NULL, };
+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 = 0;
+
+/* Local vars.
+ */
+static int overrun_count_offset = 0;
+static int inhibit_correction = 0;
+
+/* 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.
+ */
+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 && (current->signal & _NEVER_BLOCK) == 0);
+#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 ||
+ (current->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 ||
+ (current->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 &&
+ (current->signal & _DONT_BLOCK) == 0) {
+
+ 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;
+}
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen, slshen@lbl.gov