sr.c

linux 内核源代码

/*
 *  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 <[e-mail]>
 *
 *	Modified by Eric Youngdale [e-mail] to
 *	add scatter-gather, multiple outstanding request, and other
 *	enhancements.
 *
 *      Modified by Eric Youngdale [e-mail] to support loadable
 *      low-level scsi drivers.
 *
 *      Modified by Thomas Quinot [e-mail] to
 *      provide auto-eject.
 *
 *      Modified by Gerd Knorr <[e-mail]> to support the
 *      generic cdrom interface
 *
 *      Modified by Jens Axboe <[e-mail]> - Uniform sr_packet()
 *      interface, capabilities probe additions, ioctl cleanups, etc.
 *
 *	Modified by Richard Gooch <[e-mail]> to support devfs
 *
 *	Modified by Jens Axboe <[e-mail]> - support DVD-RAM
 *	transparently and lose the GHOST hack
 *
 *	Modified by Arnaldo Carvalho de Melo <[e-mail]>
 *	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 <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 MAX_RETRIES	3
#define SR_TIMEOUT	(30 * HZ)
#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 int sr_probe(struct device *);
static int sr_remove(struct device *);
static int sr_done(struct scsi_cmnd *);

static struct scsi_driver sr_template = {
	.owner			= THIS_MODULE,
	.gendrv = {
		.name   	= "sr",
		.probe		= sr_probe,
		.remove		= sr_remove,
	},
	.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 int sr_media_change(struct cdrom_device_info *, int);
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,
	.media_changed		= sr_media_change,
	.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);
}

/*
 * 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))
		goto out_put;
	goto out;

 out_put:
	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);
}

/*
 * This function checks to see if the media has been changed in the
 * CDROM drive.  It is possible that we have already sensed a change,
 * or the drive may have sensed one and not yet reported it.  We must
 * be ready for either case. This function always reports the current
 * value of the changed bit.  If flag is 0, then the changed bit is reset.
 * This function could be done as an ioctl, but we would need to have
 * an inode for that to work, and we do not always have one.
 */

static int sr_media_change(struct cdrom_device_info *cdi, int slot)
{
	struct scsi_cd *cd = cdi->handle;
	int retval;

	if (CDSL_CURRENT != slot) {
		/* no changer support */
		return -EINVAL;
	}

	retval = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES);
	if (retval) {
		/* Unable to test, unit probably not ready.  This usually
		 * means there is no disc in the drive.  Mark as changed,
		 * and we will figure it out later once the drive is
		 * available again.  */
		cd->device->changed = 1;
		return 1;	/* This will force a flush, if called from
				 * check_disk_change */
	};

	retval = cd->device->changed;
	cd->device->changed = 0;
	/* If the disk changed, the capacity will now be different,
	 * so we force a re-read of this information */
	if (retval) {
		/* check multisession offset etc */
		sr_cd_check(cdi);

		get_sectorsize(cd);
	}
	return retval;
}
 
/*
 * 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 = SCpnt->request_bufflen;
	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
	printk("sr.c done: %x\n", 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 - SCpnt->request->sector) << 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:

			/*
			 * An error occured, but it recovered.  Inform the
			 * user, but make sure that it's not treated as a
			 * hard error.
			 */
			scsi_print_sense("sr", SCpnt);
			SCpnt->result = 0;
			SCpnt->sense_buffer[0] = 0x0;
			good_bytes = this_count;
			break;

		default:
			break;
		}
	}

	return good_bytes;
}

static int sr_prep_fn(struct request_queue *q, struct request *rq)
{
	int block=0, this_count, s_size, timeout = SR_TIMEOUT;
	struct scsi_cd *cd;
	struct scsi_cmnd *SCpnt;
	struct scsi_device *sdp = q->queuedata;
	int ret;

	if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
		ret = scsi_setup_blk_pc_cmnd(sdp, rq);
		goto out;
	} else if (rq->cmd_type != REQ_TYPE_FS) {
		ret = BLKPREP_KILL;
		goto out;
	}
	ret = scsi_setup_fs_cmnd(sdp, rq);
	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, printk("Doing sr request, dev = %s, block = %d\n",
				cd->disk->disk_name, block));

	if (!cd->device || !scsi_device_online(cd->device)) {
		SCSI_LOG_HLQUEUE(2, printk("Finishing %ld sectors\n",
					rq->nr_sectors));
		SCSI_LOG_HLQUEUE(2, printk("Retry with 0x%p\n", 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
			printk("sr: can't switch blocksize: in interrupt\n");
	}

	if (s_size != 512 && s_size != 1024 && s_size != 2048) {
		scmd_printk(KERN_ERR, SCpnt, "bad sector size %d\n", s_size);
		goto out;
	}

	if (rq_data_dir(rq) == WRITE) {
		if (!cd->device->writeable)
			goto out;
		SCpnt->cmnd[0] = WRITE_10;
		SCpnt->sc_data_direction = DMA_TO_DEVICE;
 	 	cd->cdi.media_written = 1;
	} else if (rq_data_dir(rq) == READ) {
		SCpnt->cmnd[0] = READ_10;
		SCpnt->sc_data_direction = DMA_FROM_DEVICE;
	} else {
		blk_dump_rq_flags(rq, "Unknown sr command");
		goto out;
	}

	{
		struct scatterlist *sg = SCpnt->request_buffer;
		int i, size = 0;
		for (i = 0; i < SCpnt->use_sg; i++)
			size += sg[i].length;

		if (size != SCpnt->request_bufflen && SCpnt->use_sg) {
			scmd_printk(KERN_ERR, SCpnt,
				"mismatch count %d, bytes %d\n",
				size, SCpnt->request_bufflen);
			if (SCpnt->request_bufflen > size)
				SCpnt->request_bufflen = size;
		}
	}

	/*
	 * request doesn't start on hw block boundary, add scatter pads
	 */
	if (((unsigned int)rq->sector % (s_size >> 9)) ||
	    (SCpnt->request_bufflen % s_size)) {
		scmd_printk(KERN_NOTICE, SCpnt, "unaligned transfer\n");
		goto out;
	}

	this_count = (SCpnt->request_bufflen >> 9) / (s_size >> 9);


	SCSI_LOG_HLQUEUE(2, printk("%s : %s %d/%ld 512 byte blocks.\n",
				cd->cdi.name,
				(rq_data_dir(rq) == WRITE) ?
					"writing" : "reading",
				this_count, rq->nr_sectors));

	SCpnt->cmnd[1] = 0;
	block = (unsigned int)rq->sector / (s_size >> 9);

	if (this_count > 0xffff) {
		this_count = 0xffff;
		SCpnt->request_bufflen = 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;
	SCpnt->timeout_per_command = timeout;

	/*
	 * This indicates that the command is ready from our end to be
	 * queued.
	 */
	ret = BLKPREP_OK;
 out:
	return scsi_prep_return(q, rq, ret);
}

static int sr_block_open(struct inode *inode, struct file *file)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
	struct scsi_cd *cd;
	int ret = 0;

	if(!(cd = scsi_cd_get(disk)))
		return -ENXIO;

	if((ret = cdrom_open(&cd->cdi, inode, file)) != 0)
		scsi_cd_put(cd);

	return ret;
}

static int sr_block_release(struct inode *inode, struct file *file)
{
	int ret;
	struct scsi_cd *cd = scsi_cd(inode->i_bdev->bd_disk);
	ret = cdrom_release(&cd->cdi, file);
	if(ret)
		return ret;