diff options
Diffstat (limited to 'drivers/char/ftape/lowlevel/ftape-rw.c')
| -rw-r--r-- | drivers/char/ftape/lowlevel/ftape-rw.c | 1092 |
1 files changed, 0 insertions, 1092 deletions
diff --git a/drivers/char/ftape/lowlevel/ftape-rw.c b/drivers/char/ftape/lowlevel/ftape-rw.c deleted file mode 100644 index c0d6dc2cbfd..00000000000 --- a/drivers/char/ftape/lowlevel/ftape-rw.c +++ /dev/null @@ -1,1092 +0,0 @@ -/* - * 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(¤t->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(¤t->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(¤t->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(¤t->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; -} |