/*
   *  sr.c Copyright (C) 1992 David Giller
   *           Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
   *
   *  adapted from:
   *      sd.c Copyright (C) 1992 Drew Eckhardt
   *      Linux scsi disk driver by
   *              Drew Eckhardt <drew@colorado.edu>
   *
   *	Modified by Eric Youngdale ericy@andante.org to
   *	add scatter-gather, multiple outstanding request, and other
   *	enhancements.
   *
   *      Modified by Eric Youngdale eric@andante.org to support loadable
   *      low-level scsi drivers.
   *
   *      Modified by Thomas Quinot thomas@melchior.cuivre.fdn.fr to
   *      provide auto-eject.
   *
   *      Modified by Gerd Knorr <kraxel@cs.tu-berlin.de> to support the
   *      generic cdrom interface
   *
   *      Modified by Jens Axboe <axboe@suse.de> - Uniform sr_packet()
   *      interface, capabilities probe additions, ioctl cleanups, etc.
   *
   *	Modified by Richard Gooch <rgooch@atnf.csiro.au> to support devfs
   *
   *	Modified by Jens Axboe <axboe@suse.de> - support DVD-RAM
   *	transparently and lose the GHOST hack
   *
   *	Modified by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   *	check resource allocation in sr_init and some cleanups
   */
  
  #include <linux/module.h>
  #include <linux/fs.h>
  #include <linux/kernel.h>

  #include <linux/mm.h>
  #include <linux/bio.h>
  #include <linux/string.h>
  #include <linux/errno.h>
  #include <linux/cdrom.h>
  #include <linux/interrupt.h>
  #include <linux/init.h>
  #include <linux/blkdev.h>

  #include <linux/mutex.h>

  #include <linux/slab.h>

  #include <linux/pm_runtime.h>

  #include <asm/uaccess.h>
  
  #include <scsi/scsi.h>
  #include <scsi/scsi_dbg.h>
  #include <scsi/scsi_device.h>
  #include <scsi/scsi_driver.h>

  #include <scsi/scsi_cmnd.h>

  #include <scsi/scsi_eh.h>
  #include <scsi/scsi_host.h>
  #include <scsi/scsi_ioctl.h>	/* For the door lock/unlock commands */

  
  #include "scsi_logging.h"
  #include "sr.h"

  MODULE_DESCRIPTION("SCSI cdrom (sr) driver");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_CDROM_MAJOR);

  MODULE_ALIAS_SCSI_DEVICE(TYPE_ROM);
  MODULE_ALIAS_SCSI_DEVICE(TYPE_WORM);

  #define SR_DISKS	256

  #define SR_CAPABILITIES \
  	(CDC_CLOSE_TRAY|CDC_OPEN_TRAY|CDC_LOCK|CDC_SELECT_SPEED| \
  	 CDC_SELECT_DISC|CDC_MULTI_SESSION|CDC_MCN|CDC_MEDIA_CHANGED| \

  	 CDC_PLAY_AUDIO|CDC_RESET|CDC_DRIVE_STATUS| \

  	 CDC_CD_R|CDC_CD_RW|CDC_DVD|CDC_DVD_R|CDC_DVD_RAM|CDC_GENERIC_PACKET| \
  	 CDC_MRW|CDC_MRW_W|CDC_RAM)

  static DEFINE_MUTEX(sr_mutex);

  static int sr_probe(struct device *);
  static int sr_remove(struct device *);

  static int sr_init_command(struct scsi_cmnd *SCpnt);

  static int sr_done(struct scsi_cmnd *);

  static int sr_runtime_suspend(struct device *dev);
  
  static struct dev_pm_ops sr_pm_ops = {
  	.runtime_suspend	= sr_runtime_suspend,
  };

  
  static struct scsi_driver sr_template = {

  	.gendrv = {
  		.name   	= "sr",

  		.owner		= THIS_MODULE,

  		.probe		= sr_probe,
  		.remove		= sr_remove,

  		.pm		= &sr_pm_ops,

  	},

  	.init_command		= sr_init_command,

  	.done			= sr_done,

  };
  
  static unsigned long sr_index_bits[SR_DISKS / BITS_PER_LONG];
  static DEFINE_SPINLOCK(sr_index_lock);
  
  /* This semaphore is used to mediate the 0->1 reference get in the
   * face of object destruction (i.e. we can't allow a get on an
   * object after last put) */

  static DEFINE_MUTEX(sr_ref_mutex);

  
  static int sr_open(struct cdrom_device_info *, int);
  static void sr_release(struct cdrom_device_info *);
  
  static void get_sectorsize(struct scsi_cd *);
  static void get_capabilities(struct scsi_cd *);

  static unsigned int sr_check_events(struct cdrom_device_info *cdi,
  				    unsigned int clearing, int slot);

  static int sr_packet(struct cdrom_device_info *, struct packet_command *);
  
  static struct cdrom_device_ops sr_dops = {
  	.open			= sr_open,
  	.release	 	= sr_release,
  	.drive_status	 	= sr_drive_status,

  	.check_events		= sr_check_events,

  	.tray_move		= sr_tray_move,
  	.lock_door		= sr_lock_door,
  	.select_speed		= sr_select_speed,
  	.get_last_session	= sr_get_last_session,
  	.get_mcn		= sr_get_mcn,
  	.reset			= sr_reset,
  	.audio_ioctl		= sr_audio_ioctl,

  	.capability		= SR_CAPABILITIES,
  	.generic_packet		= sr_packet,
  };
  
  static void sr_kref_release(struct kref *kref);
  
  static inline struct scsi_cd *scsi_cd(struct gendisk *disk)
  {
  	return container_of(disk->private_data, struct scsi_cd, driver);
  }

  static int sr_runtime_suspend(struct device *dev)
  {
  	struct scsi_cd *cd = dev_get_drvdata(dev);
  
  	if (cd->media_present)
  		return -EBUSY;
  	else
  		return 0;
  }

  /*
   * The get and put routines for the struct scsi_cd.  Note this entity
   * has a scsi_device pointer and owns a reference to this.
   */
  static inline struct scsi_cd *scsi_cd_get(struct gendisk *disk)
  {
  	struct scsi_cd *cd = NULL;

  	mutex_lock(&sr_ref_mutex);

  	if (disk->private_data == NULL)
  		goto out;
  	cd = scsi_cd(disk);
  	kref_get(&cd->kref);

  	if (scsi_device_get(cd->device)) {
  		kref_put(&cd->kref, sr_kref_release);
  		cd = NULL;
  	}

   out:

  	mutex_unlock(&sr_ref_mutex);

  	return cd;
  }

  static void scsi_cd_put(struct scsi_cd *cd)

  {
  	struct scsi_device *sdev = cd->device;

  	mutex_lock(&sr_ref_mutex);

  	kref_put(&cd->kref, sr_kref_release);
  	scsi_device_put(sdev);

  	mutex_unlock(&sr_ref_mutex);

  }

  static unsigned int sr_get_events(struct scsi_device *sdev)
  {
  	u8 buf[8];
  	u8 cmd[] = { GET_EVENT_STATUS_NOTIFICATION,
  		     1,			/* polled */
  		     0, 0,		/* reserved */
  		     1 << 4,		/* notification class: media */
  		     0, 0,		/* reserved */
  		     0, sizeof(buf),	/* allocation length */
  		     0,			/* control */
  	};
  	struct event_header *eh = (void *)buf;
  	struct media_event_desc *med = (void *)(buf + 4);
  	struct scsi_sense_hdr sshdr;
  	int result;
  
  	result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buf, sizeof(buf),
  				  &sshdr, SR_TIMEOUT, MAX_RETRIES, NULL);
  	if (scsi_sense_valid(&sshdr) && sshdr.sense_key == UNIT_ATTENTION)
  		return DISK_EVENT_MEDIA_CHANGE;
  
  	if (result || be16_to_cpu(eh->data_len) < sizeof(*med))
  		return 0;
  
  	if (eh->nea || eh->notification_class != 0x4)
  		return 0;
  
  	if (med->media_event_code == 1)
  		return DISK_EVENT_EJECT_REQUEST;
  	else if (med->media_event_code == 2)
  		return DISK_EVENT_MEDIA_CHANGE;
  	return 0;
  }

  /*

   * This function checks to see if the media has been changed or eject
   * button has been pressed.  It is possible that we have already
   * sensed a change, or the drive may have sensed one and not yet
   * reported it.  The past events are accumulated in sdev->changed and
   * returned together with the current state.

   */

  static unsigned int sr_check_events(struct cdrom_device_info *cdi,
  				    unsigned int clearing, int slot)

  {
  	struct scsi_cd *cd = cdi->handle;

  	bool last_present;
  	struct scsi_sense_hdr sshdr;
  	unsigned int events;
  	int ret;

  	/* no changer support */
  	if (CDSL_CURRENT != slot)
  		return 0;
  
  	events = sr_get_events(cd->device);

  	cd->get_event_changed |= events & DISK_EVENT_MEDIA_CHANGE;
  
  	/*
  	 * If earlier GET_EVENT_STATUS_NOTIFICATION and TUR did not agree
  	 * for several times in a row.  We rely on TUR only for this likely
  	 * broken device, to prevent generating incorrect media changed
  	 * events for every open().
  	 */
  	if (cd->ignore_get_event) {
  		events &= ~DISK_EVENT_MEDIA_CHANGE;
  		goto do_tur;
  	}

  	/*
  	 * GET_EVENT_STATUS_NOTIFICATION is enough unless MEDIA_CHANGE
  	 * is being cleared.  Note that there are devices which hang
  	 * if asked to execute TUR repeatedly.
  	 */

  	if (cd->device->changed) {
  		events |= DISK_EVENT_MEDIA_CHANGE;
  		cd->device->changed = 0;
  		cd->tur_changed = true;
  	}

  	if (!(clearing & DISK_EVENT_MEDIA_CHANGE))
  		return events;
  do_tur:

  	/* let's see whether the media is there with TUR */
  	last_present = cd->media_present;
  	ret = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr);

  	/*
  	 * Media is considered to be present if TUR succeeds or fails with
  	 * sense data indicating something other than media-not-present
  	 * (ASC 0x3a).
  	 */

  	cd->media_present = scsi_status_is_good(ret) ||
  		(scsi_sense_valid(&sshdr) && sshdr.asc != 0x3a);

  	if (last_present != cd->media_present)

  		cd->device->changed = 1;

  	if (cd->device->changed) {
  		events |= DISK_EVENT_MEDIA_CHANGE;
  		cd->device->changed = 0;

  		cd->tur_changed = true;
  	}
  
  	if (cd->ignore_get_event)
  		return events;
  
  	/* check whether GET_EVENT is reporting spurious MEDIA_CHANGE */
  	if (!cd->tur_changed) {
  		if (cd->get_event_changed) {
  			if (cd->tur_mismatch++ > 8) {

  				sr_printk(KERN_WARNING, cd,
  					  "GET_EVENT and TUR disagree continuously, suppress GET_EVENT events
  ");

  				cd->ignore_get_event = true;
  			}
  		} else {
  			cd->tur_mismatch = 0;
  		}

  	}

  	cd->tur_changed = false;
  	cd->get_event_changed = false;

  	return events;

  }

  /*

   * sr_done is the interrupt routine for the device driver.

   *

   * It will be notified on the end of a SCSI read / write, and will take one

   * of several actions based on success or failure.
   */

  static int sr_done(struct scsi_cmnd *SCpnt)

  {
  	int result = SCpnt->result;

  	int this_count = scsi_bufflen(SCpnt);

  	int good_bytes = (result == 0 ? this_count : 0);
  	int block_sectors = 0;
  	long error_sector;
  	struct scsi_cd *cd = scsi_cd(SCpnt->request->rq_disk);
  
  #ifdef DEBUG

  	scmd_printk(KERN_INFO, SCpnt, "done: %x
  ", result);

  #endif
  
  	/*
  	 * Handle MEDIUM ERRORs or VOLUME OVERFLOWs that indicate partial
  	 * success.  Since this is a relatively rare error condition, no
  	 * care is taken to avoid unnecessary additional work such as
  	 * memcpy's that could be avoided.
  	 */
  	if (driver_byte(result) != 0 &&		/* An error occurred */
  	    (SCpnt->sense_buffer[0] & 0x7f) == 0x70) { /* Sense current */
  		switch (SCpnt->sense_buffer[2]) {
  		case MEDIUM_ERROR:
  		case VOLUME_OVERFLOW:
  		case ILLEGAL_REQUEST:
  			if (!(SCpnt->sense_buffer[0] & 0x90))
  				break;

  			error_sector = (SCpnt->sense_buffer[3] << 24) |
  				(SCpnt->sense_buffer[4] << 16) |
  				(SCpnt->sense_buffer[5] << 8) |
  				SCpnt->sense_buffer[6];
  			if (SCpnt->request->bio != NULL)
  				block_sectors =
  					bio_sectors(SCpnt->request->bio);
  			if (block_sectors < 4)
  				block_sectors = 4;
  			if (cd->device->sector_size == 2048)
  				error_sector <<= 2;
  			error_sector &= ~(block_sectors - 1);

  			good_bytes = (error_sector -
  				      blk_rq_pos(SCpnt->request)) << 9;

  			if (good_bytes < 0 || good_bytes >= this_count)
  				good_bytes = 0;
  			/*
  			 * The SCSI specification allows for the value
  			 * returned by READ CAPACITY to be up to 75 2K
  			 * sectors past the last readable block.
  			 * Therefore, if we hit a medium error within the
  			 * last 75 2K sectors, we decrease the saved size
  			 * value.
  			 */
  			if (error_sector < get_capacity(cd->disk) &&
  			    cd->capacity - error_sector < 4 * 75)
  				set_capacity(cd->disk, error_sector);
  			break;
  
  		case RECOVERED_ERROR:

  			good_bytes = this_count;
  			break;
  
  		default:
  			break;
  		}
  	}

  	return good_bytes;

  }

  static int sr_init_command(struct scsi_cmnd *SCpnt)

  {

  	int block = 0, this_count, s_size;

  	struct scsi_cd *cd;

  	struct request *rq = SCpnt->request;

  	int ret;

  	ret = scsi_init_io(SCpnt);

  	if (ret != BLKPREP_OK)
  		goto out;
  	SCpnt = rq->special;
  	cd = scsi_cd(rq->rq_disk);
  
  	/* from here on until we're complete, any goto out
  	 * is used for a killable error condition */
  	ret = BLKPREP_KILL;

  	SCSI_LOG_HLQUEUE(1, scmd_printk(KERN_INFO, SCpnt,
  		"Doing sr request, block = %d
  ", block));

  
  	if (!cd->device || !scsi_device_online(cd->device)) {

  		SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt,
  			"Finishing %u sectors
  ", blk_rq_sectors(rq)));
  		SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt,
  			"Retry with 0x%p
  ", SCpnt));

  		goto out;

  	}
  
  	if (cd->device->changed) {
  		/*
  		 * quietly refuse to do anything to a changed disc until the
  		 * changed bit has been reset
  		 */

  		goto out;

  	}
  
  	/*

  	 * we do lazy blocksize switching (when reading XA sectors,
  	 * see CDROMREADMODE2 ioctl) 
  	 */
  	s_size = cd->device->sector_size;
  	if (s_size > 2048) {
  		if (!in_interrupt())
  			sr_set_blocklength(cd, 2048);
  		else

  			scmd_printk(KERN_INFO, SCpnt,
  				    "can't switch blocksize: in interrupt
  ");

  	}
  
  	if (s_size != 512 && s_size != 1024 && s_size != 2048) {

  		scmd_printk(KERN_ERR, SCpnt, "bad sector size %d
  ", s_size);

  		goto out;

  	}

  	if (rq_data_dir(rq) == WRITE) {

  		if (!cd->writeable)

  			goto out;

  		SCpnt->cmnd[0] = WRITE_10;

  		cd->cdi.media_written = 1;

  	} else if (rq_data_dir(rq) == READ) {

  		SCpnt->cmnd[0] = READ_10;

  	} else {

  		blk_dump_rq_flags(rq, "Unknown sr command");
  		goto out;

  	}
  
  	{

  		struct scatterlist *sg;
  		int i, size = 0, sg_count = scsi_sg_count(SCpnt);

  		scsi_for_each_sg(SCpnt, sg, sg_count, i)
  			size += sg->length;
  
  		if (size != scsi_bufflen(SCpnt)) {

  			scmd_printk(KERN_ERR, SCpnt,
  				"mismatch count %d, bytes %d
  ",

  				size, scsi_bufflen(SCpnt));
  			if (scsi_bufflen(SCpnt) > size)
  				SCpnt->sdb.length = size;

  		}
  	}
  
  	/*
  	 * request doesn't start on hw block boundary, add scatter pads
  	 */

  	if (((unsigned int)blk_rq_pos(rq) % (s_size >> 9)) ||

  	    (scsi_bufflen(SCpnt) % s_size)) {

  		scmd_printk(KERN_NOTICE, SCpnt, "unaligned transfer
  ");

  		goto out;

  	}

  	this_count = (scsi_bufflen(SCpnt) >> 9) / (s_size >> 9);

  	SCSI_LOG_HLQUEUE(2, scmd_printk(KERN_INFO, SCpnt,
  					"%s %d/%u 512 byte blocks.
  ",
  					(rq_data_dir(rq) == WRITE) ?

  					"writing" : "reading",

  					this_count, blk_rq_sectors(rq)));

  
  	SCpnt->cmnd[1] = 0;

  	block = (unsigned int)blk_rq_pos(rq) / (s_size >> 9);

  
  	if (this_count > 0xffff) {
  		this_count = 0xffff;

  		SCpnt->sdb.length = this_count * s_size;

  	}
  
  	SCpnt->cmnd[2] = (unsigned char) (block >> 24) & 0xff;
  	SCpnt->cmnd[3] = (unsigned char) (block >> 16) & 0xff;
  	SCpnt->cmnd[4] = (unsigned char) (block >> 8) & 0xff;
  	SCpnt->cmnd[5] = (unsigned char) block & 0xff;
  	SCpnt->cmnd[6] = SCpnt->cmnd[9] = 0;
  	SCpnt->cmnd[7] = (unsigned char) (this_count >> 8) & 0xff;
  	SCpnt->cmnd[8] = (unsigned char) this_count & 0xff;
  
  	/*
  	 * We shouldn't disconnect in the middle of a sector, so with a dumb
  	 * host adapter, it's safe to assume that we can at least transfer
  	 * this many bytes between each connect / disconnect.
  	 */
  	SCpnt->transfersize = cd->device->sector_size;
  	SCpnt->underflow = this_count << 9;

  	SCpnt->allowed = MAX_RETRIES;

  
  	/*

  	 * This indicates that the command is ready from our end to be
  	 * queued.
  	 */

  	ret = BLKPREP_OK;
   out:

  	return ret;

  }

  static int sr_block_open(struct block_device *bdev, fmode_t mode)

  {

  	struct scsi_cd *cd;

  	int ret = -ENXIO;

  	mutex_lock(&sr_mutex);

  	cd = scsi_cd_get(bdev->bd_disk);

  	if (cd) {
  		ret = cdrom_open(&cd->cdi, bdev, mode);
  		if (ret)
  			scsi_cd_put(cd);
  	}

  	mutex_unlock(&sr_mutex);

  	return ret;
  }

  static void sr_block_release(struct gendisk *disk, fmode_t mode)

  {

  	struct scsi_cd *cd = scsi_cd(disk);

  	mutex_lock(&sr_mutex);

  	cdrom_release(&cd->cdi, mode);

  	scsi_cd_put(cd);

  	mutex_unlock(&sr_mutex);

  }

  static int sr_block_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,

  			  unsigned long arg)
  {

  	struct scsi_cd *cd = scsi_cd(bdev->bd_disk);

  	struct scsi_device *sdev = cd->device;

  	void __user *argp = (void __user *)arg;
  	int ret;

  	mutex_lock(&sr_mutex);

  	ret = scsi_ioctl_block_when_processing_errors(sdev, cmd,
  			(mode & FMODE_NDELAY) != 0);
  	if (ret)
  		goto out;

  	/*
  	 * Send SCSI addressing ioctls directly to mid level, send other
  	 * ioctls to cdrom/block level.
  	 */
  	switch (cmd) {
  	case SCSI_IOCTL_GET_IDLUN:
  	case SCSI_IOCTL_GET_BUS_NUMBER:

  		ret = scsi_ioctl(sdev, cmd, argp);
  		goto out;

  	}

  	ret = cdrom_ioctl(&cd->cdi, bdev, mode, cmd, arg);

  	if (ret != -ENOSYS)

  		goto out;

  	ret = scsi_ioctl(sdev, cmd, argp);
  
  out:

  	mutex_unlock(&sr_mutex);

  	return ret;

  }

  static unsigned int sr_block_check_events(struct gendisk *disk,
  					  unsigned int clearing)

  {
  	struct scsi_cd *cd = scsi_cd(disk);

  	if (atomic_read(&cd->device->disk_events_disable_depth))
  		return 0;

  	return cdrom_check_events(&cd->cdi, clearing);

  }
  
  static int sr_block_revalidate_disk(struct gendisk *disk)
  {
  	struct scsi_cd *cd = scsi_cd(disk);
  	struct scsi_sense_hdr sshdr;
  
  	/* if the unit is not ready, nothing more to do */
  	if (scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr))

  		goto out;

  
  	sr_cd_check(&cd->cdi);
  	get_sectorsize(cd);

  out:

  	return 0;

  }

  static const struct block_device_operations sr_bdops =

  {
  	.owner		= THIS_MODULE,

  	.open		= sr_block_open,
  	.release	= sr_block_release,

  	.ioctl		= sr_block_ioctl,

  	.check_events	= sr_block_check_events,
  	.revalidate_disk = sr_block_revalidate_disk,

  	/* 
  	 * No compat_ioctl for now because sr_block_ioctl never

  	 * seems to pass arbitrary ioctls down to host drivers.

  	 */
  };
  
  static int sr_open(struct cdrom_device_info *cdi, int purpose)
  {
  	struct scsi_cd *cd = cdi->handle;
  	struct scsi_device *sdev = cd->device;
  	int retval;
  
  	/*
  	 * If the device is in error recovery, wait until it is done.
  	 * If the device is offline, then disallow any access to it.
  	 */
  	retval = -ENXIO;
  	if (!scsi_block_when_processing_errors(sdev))
  		goto error_out;

  	return 0;
  
  error_out:
  	return retval;	
  }
  
  static void sr_release(struct cdrom_device_info *cdi)
  {
  	struct scsi_cd *cd = cdi->handle;
  
  	if (cd->device->sector_size > 2048)
  		sr_set_blocklength(cd, 2048);
  
  }
  
  static int sr_probe(struct device *dev)
  {
  	struct scsi_device *sdev = to_scsi_device(dev);
  	struct gendisk *disk;
  	struct scsi_cd *cd;
  	int minor, error;

  	scsi_autopm_get_device(sdev);

  	error = -ENODEV;
  	if (sdev->type != TYPE_ROM && sdev->type != TYPE_WORM)
  		goto fail;
  
  	error = -ENOMEM;

  	cd = kzalloc(sizeof(*cd), GFP_KERNEL);

  	if (!cd)
  		goto fail;

  
  	kref_init(&cd->kref);
  
  	disk = alloc_disk(1);
  	if (!disk)
  		goto fail_free;
  
  	spin_lock(&sr_index_lock);
  	minor = find_first_zero_bit(sr_index_bits, SR_DISKS);
  	if (minor == SR_DISKS) {
  		spin_unlock(&sr_index_lock);
  		error = -EBUSY;
  		goto fail_put;
  	}
  	__set_bit(minor, sr_index_bits);
  	spin_unlock(&sr_index_lock);
  
  	disk->major = SCSI_CDROM_MAJOR;
  	disk->first_minor = minor;
  	sprintf(disk->disk_name, "sr%d", minor);
  	disk->fops = &sr_bdops;

  	disk->flags = GENHD_FL_CD | GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;

  	disk->events = DISK_EVENT_MEDIA_CHANGE | DISK_EVENT_EJECT_REQUEST;

  	blk_queue_rq_timeout(sdev->request_queue, SR_TIMEOUT);

  	cd->device = sdev;
  	cd->disk = disk;
  	cd->driver = &sr_template;
  	cd->disk = disk;
  	cd->capacity = 0x1fffff;

  	cd->device->changed = 1;	/* force recheck CD type */

  	cd->media_present = 1;

  	cd->use = 1;
  	cd->readcd_known = 0;
  	cd->readcd_cdda = 0;
  
  	cd->cdi.ops = &sr_dops;
  	cd->cdi.handle = cd;
  	cd->cdi.mask = 0;
  	cd->cdi.capacity = 1;
  	sprintf(cd->cdi.name, "sr%d", minor);
  
  	sdev->sector_size = 2048;	/* A guess, just in case */
  
  	/* FIXME: need to handle a get_capabilities failure properly ?? */
  	get_capabilities(cd);
  	sr_vendor_init(cd);

  	disk->driverfs_dev = &sdev->sdev_gendev;
  	set_capacity(disk, cd->capacity);
  	disk->private_data = &cd->driver;
  	disk->queue = sdev->request_queue;
  	cd->cdi.disk = disk;
  
  	if (register_cdrom(&cd->cdi))
  		goto fail_put;

  	/*
  	 * Initialize block layer runtime PM stuffs before the
  	 * periodic event checking request gets started in add_disk.
  	 */
  	blk_pm_runtime_init(sdev->request_queue, dev);

  	dev_set_drvdata(dev, cd);
  	disk->flags |= GENHD_FL_REMOVABLE;
  	add_disk(disk);

  	sdev_printk(KERN_DEBUG, sdev,
  		    "Attached scsi CD-ROM %s
  ", cd->cdi.name);

  	scsi_autopm_put_device(cd->device);

  	return 0;
  
  fail_put:
  	put_disk(disk);
  fail_free:
  	kfree(cd);
  fail:

  	scsi_autopm_put_device(sdev);

  	return error;
  }
  
  
  static void get_sectorsize(struct scsi_cd *cd)
  {
  	unsigned char cmd[10];

  	unsigned char buffer[8];

  	int the_result, retries = 3;
  	int sector_size;

  	struct request_queue *queue;

  	do {
  		cmd[0] = READ_CAPACITY;
  		memset((void *) &cmd[1], 0, 9);

  		memset(buffer, 0, sizeof(buffer));

  
  		/* Do the command and wait.. */

  		the_result = scsi_execute_req(cd->device, cmd, DMA_FROM_DEVICE,

  					      buffer, sizeof(buffer), NULL,

  					      SR_TIMEOUT, MAX_RETRIES, NULL);

  		retries--;
  
  	} while (the_result && retries);

  	if (the_result) {
  		cd->capacity = 0x1fffff;
  		sector_size = 2048;	/* A guess, just in case */

  	} else {

  		long last_written;
  
  		cd->capacity = 1 + ((buffer[0] << 24) | (buffer[1] << 16) |
  				    (buffer[2] << 8) | buffer[3]);
  		/*
  		 * READ_CAPACITY doesn't return the correct size on
  		 * certain UDF media.  If last_written is larger, use
  		 * it instead.
  		 *
  		 * http://bugzilla.kernel.org/show_bug.cgi?id=9668
  		 */
  		if (!cdrom_get_last_written(&cd->cdi, &last_written))
  			cd->capacity = max_t(long, cd->capacity, last_written);

  		sector_size = (buffer[4] << 24) |
  		    (buffer[5] << 16) | (buffer[6] << 8) | buffer[7];
  		switch (sector_size) {
  			/*
  			 * HP 4020i CD-Recorder reports 2340 byte sectors
  			 * Philips CD-Writers report 2352 byte sectors
  			 *
  			 * Use 2k sectors for them..
  			 */
  		case 0:
  		case 2340:
  		case 2352:
  			sector_size = 2048;
  			/* fall through */
  		case 2048:
  			cd->capacity *= 4;
  			/* fall through */
  		case 512:
  			break;
  		default:

  			sr_printk(KERN_INFO, cd,
  				  "unsupported sector size %d.", sector_size);

  			cd->capacity = 0;

  		}
  
  		cd->device->sector_size = sector_size;
  
  		/*
  		 * Add this so that we have the ability to correctly gauge
  		 * what the device is capable of.
  		 */

  		set_capacity(cd->disk, cd->capacity);
  	}
  
  	queue = cd->device->request_queue;

  	blk_queue_logical_block_size(queue, sector_size);

  	return;

  }
  
  static void get_capabilities(struct scsi_cd *cd)
  {
  	unsigned char *buffer;
  	struct scsi_mode_data data;

  	struct scsi_sense_hdr sshdr;

  	int rc, n;

  	static const char *loadmech[] =

  	{
  		"caddy",
  		"tray",
  		"pop-up",
  		"",
  		"changer",
  		"cartridge changer",
  		"",
  		""
  	};

  
  	/* allocate transfer buffer */
  	buffer = kmalloc(512, GFP_KERNEL | GFP_DMA);
  	if (!buffer) {

  		sr_printk(KERN_ERR, cd, "out of memory.
  ");

  		return;
  	}

  	/* eat unit attentions */

  	scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr);

  
  	/* ask for mode page 0x2a */
  	rc = scsi_mode_sense(cd->device, 0, 0x2a, buffer, 128,

  			     SR_TIMEOUT, 3, &data, NULL);

  
  	if (!scsi_status_is_good(rc)) {
  		/* failed, drive doesn't have capabilities mode page */
  		cd->cdi.speed = 1;
  		cd->cdi.mask |= (CDC_CD_R | CDC_CD_RW | CDC_DVD_R |

  				 CDC_DVD | CDC_DVD_RAM |
  				 CDC_SELECT_DISC | CDC_SELECT_SPEED |
  				 CDC_MRW | CDC_MRW_W | CDC_RAM);

  		kfree(buffer);

  		sr_printk(KERN_INFO, cd, "scsi-1 drive");

  		return;
  	}
  
  	n = data.header_length + data.block_descriptor_length;
  	cd->cdi.speed = ((buffer[n + 8] << 8) + buffer[n + 9]) / 176;
  	cd->readcd_known = 1;
  	cd->readcd_cdda = buffer[n + 5] & 0x01;
  	/* print some capability bits */

  	sr_printk(KERN_INFO, cd,
  		  "scsi3-mmc drive: %dx/%dx %s%s%s%s%s%s
  ",
  		  ((buffer[n + 14] << 8) + buffer[n + 15]) / 176,
  		  cd->cdi.speed,
  		  buffer[n + 3] & 0x01 ? "writer " : "", /* CD Writer */
  		  buffer[n + 3] & 0x20 ? "dvd-ram " : "",
  		  buffer[n + 2] & 0x02 ? "cd/rw " : "", /* can read rewriteable */
  		  buffer[n + 4] & 0x20 ? "xa/form2 " : "",	/* can read xa/from2 */
  		  buffer[n + 5] & 0x01 ? "cdda " : "", /* can read audio data */
  		  loadmech[buffer[n + 6] >> 5]);

  	if ((buffer[n + 6] >> 5) == 0)
  		/* caddy drives can't close tray... */
  		cd->cdi.mask |= CDC_CLOSE_TRAY;
  	if ((buffer[n + 2] & 0x8) == 0)
  		/* not a DVD drive */
  		cd->cdi.mask |= CDC_DVD;

  	if ((buffer[n + 3] & 0x20) == 0)

  		/* can't write DVD-RAM media */
  		cd->cdi.mask |= CDC_DVD_RAM;
  	if ((buffer[n + 3] & 0x10) == 0)
  		/* can't write DVD-R media */
  		cd->cdi.mask |= CDC_DVD_R;
  	if ((buffer[n + 3] & 0x2) == 0)
  		/* can't write CD-RW media */
  		cd->cdi.mask |= CDC_CD_RW;
  	if ((buffer[n + 3] & 0x1) == 0)
  		/* can't write CD-R media */
  		cd->cdi.mask |= CDC_CD_R;
  	if ((buffer[n + 6] & 0x8) == 0)
  		/* can't eject */
  		cd->cdi.mask |= CDC_OPEN_TRAY;
  
  	if ((buffer[n + 6] >> 5) == mechtype_individual_changer ||
  	    (buffer[n + 6] >> 5) == mechtype_cartridge_changer)
  		cd->cdi.capacity =
  		    cdrom_number_of_slots(&cd->cdi);
  	if (cd->cdi.capacity <= 1)
  		/* not a changer */
  		cd->cdi.mask |= CDC_SELECT_DISC;
  	/*else    I don't think it can close its tray
  		cd->cdi.mask |= CDC_CLOSE_TRAY; */
  
  	/*
  	 * if DVD-RAM, MRW-W or CD-RW, we are randomly writable
  	 */
  	if ((cd->cdi.mask & (CDC_DVD_RAM | CDC_MRW_W | CDC_RAM | CDC_CD_RW)) !=
  			(CDC_DVD_RAM | CDC_MRW_W | CDC_RAM | CDC_CD_RW)) {

  		cd->writeable = 1;

  	}

  	kfree(buffer);
  }
  
  /*
   * sr_packet() is the entry point for the generic commands generated

   * by the Uniform CD-ROM layer.

   */
  static int sr_packet(struct cdrom_device_info *cdi,
  		struct packet_command *cgc)
  {

  	struct scsi_cd *cd = cdi->handle;
  	struct scsi_device *sdev = cd->device;
  
  	if (cgc->cmd[0] == GPCMD_READ_DISC_INFO && sdev->no_read_disc_info)
  		return -EDRIVE_CANT_DO_THIS;

  	if (cgc->timeout <= 0)
  		cgc->timeout = IOCTL_TIMEOUT;

  	sr_do_ioctl(cd, cgc);

  
  	return cgc->stat;
  }
  
  /**
   *	sr_kref_release - Called to free the scsi_cd structure
   *	@kref: pointer to embedded kref
   *

   *	sr_ref_mutex must be held entering this routine.  Because it is

   *	called on last put, you should always use the scsi_cd_get()
   *	scsi_cd_put() helpers which manipulate the semaphore directly
   *	and never do a direct kref_put().
   **/
  static void sr_kref_release(struct kref *kref)
  {
  	struct scsi_cd *cd = container_of(kref, struct scsi_cd, kref);
  	struct gendisk *disk = cd->disk;
  
  	spin_lock(&sr_index_lock);

  	clear_bit(MINOR(disk_devt(disk)), sr_index_bits);

  	spin_unlock(&sr_index_lock);
  
  	unregister_cdrom(&cd->cdi);
  
  	disk->private_data = NULL;
  
  	put_disk(disk);
  
  	kfree(cd);
  }
  
  static int sr_remove(struct device *dev)
  {
  	struct scsi_cd *cd = dev_get_drvdata(dev);

  	scsi_autopm_get_device(cd->device);

  	del_gendisk(cd->disk);

  	mutex_lock(&sr_ref_mutex);

  	kref_put(&cd->kref, sr_kref_release);

  	mutex_unlock(&sr_ref_mutex);

  
  	return 0;
  }
  
  static int __init init_sr(void)
  {
  	int rc;
  
  	rc = register_blkdev(SCSI_CDROM_MAJOR, "sr");
  	if (rc)
  		return rc;

  	rc = scsi_register_driver(&sr_template.gendrv);
  	if (rc)
  		unregister_blkdev(SCSI_CDROM_MAJOR, "sr");
  
  	return rc;

  }
  
  static void __exit exit_sr(void)
  {
  	scsi_unregister_driver(&sr_template.gendrv);
  	unregister_blkdev(SCSI_CDROM_MAJOR, "sr");
  }
  
  module_init(init_sr);
  module_exit(exit_sr);
  MODULE_LICENSE("GPL");