ftape-rw.c

linux-2.6.15.6

/*
 *      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);
	}