ide-cd.c

linux 内核源代码

		rq->buffer += SECTOR_SIZE;
		--rq->current_nr_sectors;
		--rq->nr_sectors;
		++rq->sector;
	}

	/* If we've satisfied the current request,
	   terminate it successfully. */
	if (rq->nr_sectors == 0) {
		cdrom_end_request(drive, 1);
		return -1;
	}

	/* Move on to the next buffer if needed. */
	if (rq->current_nr_sectors == 0)
		cdrom_end_request(drive, 1);

	/* If this condition does not hold, then the kluge i use to
	   represent the number of sectors to skip at the start of a transfer
	   will fail.  I think that this will never happen, but let's be
	   paranoid and check. */
	if (rq->current_nr_sectors < bio_cur_sectors(rq->bio) &&
	    (rq->sector & (sectors_per_frame - 1))) {
		printk(KERN_ERR "%s: cdrom_read_from_buffer: buffer botch (%ld)\n",
			drive->name, (long)rq->sector);
		cdrom_end_request(drive, 0);
		return -1;
	}

	return 0;
}

/*
 * Routine to send a read packet command to the drive.
 * This is usually called directly from cdrom_start_read.
 * However, for drq_interrupt devices, it is called from an interrupt
 * when the drive is ready to accept the command.
 */
static ide_startstop_t cdrom_start_read_continuation (ide_drive_t *drive)
{
	struct request *rq = HWGROUP(drive)->rq;
	unsigned short sectors_per_frame;
	int nskip;

	sectors_per_frame = queue_hardsect_size(drive->queue) >> SECTOR_BITS;

	/* If the requested sector doesn't start on a cdrom block boundary,
	   we must adjust the start of the transfer so that it does,
	   and remember to skip the first few sectors.
	   If the CURRENT_NR_SECTORS field is larger than the size
	   of the buffer, it will mean that we're to skip a number
	   of sectors equal to the amount by which CURRENT_NR_SECTORS
	   is larger than the buffer size. */
	nskip = rq->sector & (sectors_per_frame - 1);
	if (nskip > 0) {
		/* Sanity check... */
		if (rq->current_nr_sectors != bio_cur_sectors(rq->bio) &&
			(rq->sector & (sectors_per_frame - 1))) {
			printk(KERN_ERR "%s: cdrom_start_read_continuation: buffer botch (%u)\n",
				drive->name, rq->current_nr_sectors);
			cdrom_end_request(drive, 0);
			return ide_stopped;
		}
		rq->current_nr_sectors += nskip;
	}

	/* Set up the command */
	rq->timeout = ATAPI_WAIT_PC;

	/* Send the command to the drive and return. */
	return cdrom_transfer_packet_command(drive, rq, &cdrom_read_intr);
}


#define IDECD_SEEK_THRESHOLD	(1000)			/* 1000 blocks */
#define IDECD_SEEK_TIMER	(5 * WAIT_MIN_SLEEP)	/* 100 ms */
#define IDECD_SEEK_TIMEOUT	(2 * WAIT_CMD)		/* 20 sec */

static ide_startstop_t cdrom_seek_intr (ide_drive_t *drive)
{
	struct cdrom_info *info = drive->driver_data;
	int stat;
	static int retry = 10;

	if (cdrom_decode_status(drive, 0, &stat))
		return ide_stopped;
	CDROM_CONFIG_FLAGS(drive)->seeking = 1;

	if (retry && time_after(jiffies, info->start_seek + IDECD_SEEK_TIMER)) {
		if (--retry == 0) {
			/*
			 * this condition is far too common, to bother
			 * users about it
			 */
			/* printk("%s: disabled DSC seek overlap\n", drive->name);*/ 
			drive->dsc_overlap = 0;
		}
	}
	return ide_stopped;
}

static ide_startstop_t cdrom_start_seek_continuation (ide_drive_t *drive)
{
	struct request *rq = HWGROUP(drive)->rq;
	sector_t frame = rq->sector;

	sector_div(frame, queue_hardsect_size(drive->queue) >> SECTOR_BITS);

	memset(rq->cmd, 0, sizeof(rq->cmd));
	rq->cmd[0] = GPCMD_SEEK;
	put_unaligned(cpu_to_be32(frame), (unsigned int *) &rq->cmd[2]);

	rq->timeout = ATAPI_WAIT_PC;
	return cdrom_transfer_packet_command(drive, rq, &cdrom_seek_intr);
}

static ide_startstop_t cdrom_start_seek (ide_drive_t *drive, unsigned int block)
{
	struct cdrom_info *info = drive->driver_data;

	info->dma = 0;
	info->start_seek = jiffies;
	return cdrom_start_packet_command(drive, 0, cdrom_start_seek_continuation);
}

/* Fix up a possibly partially-processed request so that we can
   start it over entirely, or even put it back on the request queue. */
static void restore_request (struct request *rq)
{
	if (rq->buffer != bio_data(rq->bio)) {
		sector_t n = (rq->buffer - (char *) bio_data(rq->bio)) / SECTOR_SIZE;

		rq->buffer = bio_data(rq->bio);
		rq->nr_sectors += n;
		rq->sector -= n;
	}
	rq->hard_cur_sectors = rq->current_nr_sectors = bio_cur_sectors(rq->bio);
	rq->hard_nr_sectors = rq->nr_sectors;
	rq->hard_sector = rq->sector;
	rq->q->prep_rq_fn(rq->q, rq);
}

/*
 * Start a read request from the CD-ROM.
 */
static ide_startstop_t cdrom_start_read (ide_drive_t *drive, unsigned int block)
{
	struct cdrom_info *info = drive->driver_data;
	struct request *rq = HWGROUP(drive)->rq;
	unsigned short sectors_per_frame;

	sectors_per_frame = queue_hardsect_size(drive->queue) >> SECTOR_BITS;

	/* We may be retrying this request after an error.  Fix up
	   any weirdness which might be present in the request packet. */
	restore_request(rq);

	/* Satisfy whatever we can of this request from our cached sector. */
	if (cdrom_read_from_buffer(drive))
		return ide_stopped;

	/* Clear the local sector buffer. */
	info->nsectors_buffered = 0;

	/* use dma, if possible. */
	info->dma = drive->using_dma;
	if ((rq->sector & (sectors_per_frame - 1)) ||
	    (rq->nr_sectors & (sectors_per_frame - 1)))
		info->dma = 0;

	/* Start sending the read request to the drive. */
	return cdrom_start_packet_command(drive, 32768, cdrom_start_read_continuation);
}

/****************************************************************************
 * Execute all other packet commands.
 */

/* Interrupt routine for packet command completion. */
static ide_startstop_t cdrom_pc_intr (ide_drive_t *drive)
{
	int ireason, len, thislen;
	struct request *rq = HWGROUP(drive)->rq;
	u8 lowcyl = 0, highcyl = 0;
	int stat;

	/* Check for errors. */
	if (cdrom_decode_status(drive, 0, &stat))
		return ide_stopped;

	/* Read the interrupt reason and the transfer length. */
	ireason = HWIF(drive)->INB(IDE_IREASON_REG) & 0x3;
	lowcyl  = HWIF(drive)->INB(IDE_BCOUNTL_REG);
	highcyl = HWIF(drive)->INB(IDE_BCOUNTH_REG);

	len = lowcyl + (256 * highcyl);

	/* If DRQ is clear, the command has completed.
	   Complain if we still have data left to transfer. */
	if ((stat & DRQ_STAT) == 0) {
		/* Some of the trailing request sense fields are optional, and
		   some drives don't send them.  Sigh. */
		if (rq->cmd[0] == GPCMD_REQUEST_SENSE &&
		    rq->data_len > 0 &&
		    rq->data_len <= 5) {
			while (rq->data_len > 0) {
				*(unsigned char *)rq->data++ = 0;
				--rq->data_len;
			}
		}

		if (rq->data_len == 0)
			cdrom_end_request(drive, 1);
		else {
			/* Comment this out, because this always happens 
			   right after a reset occurs, and it is annoying to 
			   always print expected stuff.  */
			/*
			printk ("%s: cdrom_pc_intr: data underrun %d\n",
				drive->name, pc->buflen);
			*/
			rq->cmd_flags |= REQ_FAILED;
			cdrom_end_request(drive, 0);
		}
		return ide_stopped;
	}

	/* Figure out how much data to transfer. */
	thislen = rq->data_len;
	if (thislen > len) thislen = len;

	/* The drive wants to be written to. */
	if (ireason == 0) {
		if (!rq->data) {
			blk_dump_rq_flags(rq, "cdrom_pc_intr, write");
			goto confused;
		}
		/* Transfer the data. */
		HWIF(drive)->atapi_output_bytes(drive, rq->data, thislen);

		/* If we haven't moved enough data to satisfy the drive,
		   add some padding. */
		while (len > thislen) {
			int dum = 0;
			HWIF(drive)->atapi_output_bytes(drive, &dum, sizeof(dum));
			len -= sizeof(dum);
		}

		/* Keep count of how much data we've moved. */
		rq->data += thislen;
		rq->data_len -= thislen;
	}

	/* Same drill for reading. */
	else if (ireason == 2) {
		if (!rq->data) {
			blk_dump_rq_flags(rq, "cdrom_pc_intr, read");
			goto confused;
		}
		/* Transfer the data. */
		HWIF(drive)->atapi_input_bytes(drive, rq->data, thislen);

		/* If we haven't moved enough data to satisfy the drive,
		   add some padding. */
		while (len > thislen) {
			int dum = 0;
			HWIF(drive)->atapi_input_bytes(drive, &dum, sizeof(dum));
			len -= sizeof(dum);
		}

		/* Keep count of how much data we've moved. */
		rq->data += thislen;
		rq->data_len -= thislen;

		if (blk_sense_request(rq))
			rq->sense_len += thislen;
	} else {
confused:
		printk (KERN_ERR "%s: cdrom_pc_intr: The drive "
			"appears confused (ireason = 0x%02x). "
			"Trying to recover by ending request.\n",
			drive->name, ireason);
		rq->cmd_flags |= REQ_FAILED;
		cdrom_end_request(drive, 0);
		return ide_stopped;
	}

	/* Now we wait for another interrupt. */
	ide_set_handler(drive, &cdrom_pc_intr, ATAPI_WAIT_PC, cdrom_timer_expiry);
	return ide_started;
}

static ide_startstop_t cdrom_do_pc_continuation (ide_drive_t *drive)
{
	struct request *rq = HWGROUP(drive)->rq;

	if (!rq->timeout)
		rq->timeout = ATAPI_WAIT_PC;

	/* Send the command to the drive and return. */
	return cdrom_transfer_packet_command(drive, rq, &cdrom_pc_intr);
}


static ide_startstop_t cdrom_do_packet_command (ide_drive_t *drive)
{
	int len;
	struct request *rq = HWGROUP(drive)->rq;
	struct cdrom_info *info = drive->driver_data;

	info->dma = 0;
	rq->cmd_flags &= ~REQ_FAILED;
	len = rq->data_len;

	/* Start sending the command to the drive. */
	return cdrom_start_packet_command(drive, len, cdrom_do_pc_continuation);
}


static int cdrom_queue_packet_command(ide_drive_t *drive, struct request *rq)
{
	struct request_sense sense;
	int retries = 10;
	unsigned int flags = rq->cmd_flags;

	if (rq->sense == NULL)
		rq->sense = &sense;

	/* Start of retry loop. */
	do {
		int error;
		unsigned long time = jiffies;
		rq->cmd_flags = flags;

		error = ide_do_drive_cmd(drive, rq, ide_wait);
		time = jiffies - time;

		/* FIXME: we should probably abort/retry or something 
		 * in case of failure */
		if (rq->cmd_flags & REQ_FAILED) {
			/* The request failed.  Retry if it was due to a unit
			   attention status
			   (usually means media was changed). */
			struct request_sense *reqbuf = rq->sense;

			if (reqbuf->sense_key == UNIT_ATTENTION)
				cdrom_saw_media_change(drive);
			else if (reqbuf->sense_key == NOT_READY &&
				 reqbuf->asc == 4 && reqbuf->ascq != 4) {
				/* The drive is in the process of loading
				   a disk.  Retry, but wait a little to give
				   the drive time to complete the load. */
				ssleep(2);
			} else {
				/* Otherwise, don't retry. */
				retries = 0;
			}
			--retries;
		}

		/* End of retry loop. */
	} while ((rq->cmd_flags & REQ_FAILED) && retries >= 0);

	/* Return an error if the command failed. */
	return (rq->cmd_flags & REQ_FAILED) ? -EIO : 0;
}

/*
 * Write handling
 */
static int cdrom_write_check_ireason(ide_drive_t *drive, int len, int ireason)
{
	/* Two notes about IDE interrupt reason here - 0 means that
	 * the drive wants to receive data from us, 2 means that
	 * the drive is expecting to transfer data to us.
	 */
	if (ireason == 0)
		return 0;
	else if (ireason == 2) {
		/* Whoops... The drive wants to send data. */
		printk(KERN_ERR "%s: %s: wrong transfer direction!\n",
				drive->name, __FUNCTION__);

		while (len > 0) {
			int dum = 0;
			HWIF(drive)->atapi_input_bytes(drive, &dum, sizeof(dum));
			len -= sizeof(dum);
		}
	} else {
		/* Drive wants a command packet, or invalid ireason... */
		printk(KERN_ERR "%s: %s: bad interrupt reason 0x%02x\n",
				drive->name, __FUNCTION__, ireason);
	}

	cdrom_end_request(drive, 0);
	return 1;
}

typedef void (xfer_func_t)(ide_drive_t *, void *, u32);

/*
 * best way to deal with dma that is not sector aligned right now... note
 * that in this path we are not using ->data or ->buffer at all. this irs
 * can replace cdrom_pc_intr, cdrom_read_intr, and cdrom_write_intr in the
 * future.
 */
static ide_startstop_t cdrom_newpc_intr(ide_drive_t *drive)
{
	struct cdrom_info *info = drive->driver_data;
	struct request *rq = HWGROUP(drive)->rq;
	int dma_error, dma, stat, ireason, len, thislen;
	u8 lowcyl, highcyl;
	xfer_func_t *xferfunc;
	unsigned long flags;

	/* Check for errors. */
	dma_error = 0;
	dma = info->dma;
	if (dma) {