Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2085 insertions, 0 deletions

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
new file mode 100644
index 000000000..6f26634b2
--- /dev/null
+++ b/drivers/ide/ide-tape.c
@@ -0,0 +1,2085 @@
+/*
+ * IDE ATAPI streaming tape driver.
+ *
+ * Copyright (C) 1995-1999  Gadi Oxman <gadio@netvision.net.il>
+ * Copyright (C) 2003-2005  Bartlomiej Zolnierkiewicz
+ *
+ * This driver was constructed as a student project in the software laboratory
+ * of the faculty of electrical engineering in the Technion - Israel's
+ * Institute Of Technology, with the guide of Avner Lottem and Dr. Ilana David.
+ *
+ * It is hereby placed under the terms of the GNU general public license.
+ * (See linux/COPYING).
+ *
+ * For a historical changelog see
+ * Documentation/ide/ChangeLog.ide-tape.1995-2002
+ */
+
+#define DRV_NAME "ide-tape"
+
+#define IDETAPE_VERSION "1.20"
+
+#include <linux/compat.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/timer.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/major.h>
+#include <linux/errno.h>
+#include <linux/genhd.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/pci.h>
+#include <linux/ide.h>
+#include <linux/completion.h>
+#include <linux/bitops.h>
+#include <linux/mutex.h>
+#include <scsi/scsi.h>
+
+#include <asm/byteorder.h>
+#include <linux/uaccess.h>
+#include <linux/io.h>
+#include <asm/unaligned.h>
+#include <linux/mtio.h>
+
+/* define to see debug info */
+#undef IDETAPE_DEBUG_LOG
+
+#ifdef IDETAPE_DEBUG_LOG
+#define ide_debug_log(lvl, fmt, args...) __ide_debug_log(lvl, fmt, ## args)
+#else
+#define ide_debug_log(lvl, fmt, args...) do {} while (0)
+#endif
+
+/**************************** Tunable parameters *****************************/
+/*
+ * After each failed packet command we issue a request sense command and retry
+ * the packet command IDETAPE_MAX_PC_RETRIES times.
+ *
+ * Setting IDETAPE_MAX_PC_RETRIES to 0 will disable retries.
+ */
+#define IDETAPE_MAX_PC_RETRIES		3
+
+/*
+ * The following parameter is used to select the point in the internal tape fifo
+ * in which we will start to refill the buffer. Decreasing the following
+ * parameter will improve the system's latency and interactive response, while
+ * using a high value might improve system throughput.
+ */
+#define IDETAPE_FIFO_THRESHOLD		2
+
+/*
+ * DSC polling parameters.
+ *
+ * Polling for DSC (a single bit in the status register) is a very important
+ * function in ide-tape. There are two cases in which we poll for DSC:
+ *
+ * 1. Before a read/write packet command, to ensure that we can transfer data
+ * from/to the tape's data buffers, without causing an actual media access.
+ * In case the tape is not ready yet, we take out our request from the device
+ * request queue, so that ide.c could service requests from the other device
+ * on the same interface in the meantime.
+ *
+ * 2. After the successful initialization of a "media access packet command",
+ * which is a command that can take a long time to complete (the interval can
+ * range from several seconds to even an hour). Again, we postpone our request
+ * in the middle to free the bus for the other device. The polling frequency
+ * here should be lower than the read/write frequency since those media access
+ * commands are slow. We start from a "fast" frequency - IDETAPE_DSC_MA_FAST
+ * (1 second), and if we don't receive DSC after IDETAPE_DSC_MA_THRESHOLD
+ * (5 min), we switch it to a lower frequency - IDETAPE_DSC_MA_SLOW (1 min).
+ *
+ * We also set a timeout for the timer, in case something goes wrong. The
+ * timeout should be longer then the maximum execution time of a tape operation.
+ */
+
+/* DSC timings. */
+#define IDETAPE_DSC_RW_MIN		5*HZ/100	/* 50 msec */
+#define IDETAPE_DSC_RW_MAX		40*HZ/100	/* 400 msec */
+#define IDETAPE_DSC_RW_TIMEOUT		2*60*HZ		/* 2 minutes */
+#define IDETAPE_DSC_MA_FAST		2*HZ		/* 2 seconds */
+#define IDETAPE_DSC_MA_THRESHOLD	5*60*HZ		/* 5 minutes */
+#define IDETAPE_DSC_MA_SLOW		30*HZ		/* 30 seconds */
+#define IDETAPE_DSC_MA_TIMEOUT		2*60*60*HZ	/* 2 hours */
+
+/*************************** End of tunable parameters ***********************/
+
+/* tape directions */
+enum {
+	IDETAPE_DIR_NONE  = (1 << 0),
+	IDETAPE_DIR_READ  = (1 << 1),
+	IDETAPE_DIR_WRITE = (1 << 2),
+};
+
+/* Tape door status */
+#define DOOR_UNLOCKED			0
+#define DOOR_LOCKED			1
+#define DOOR_EXPLICITLY_LOCKED		2
+
+/* Some defines for the SPACE command */
+#define IDETAPE_SPACE_OVER_FILEMARK	1
+#define IDETAPE_SPACE_TO_EOD		3
+
+/* Some defines for the LOAD UNLOAD command */
+#define IDETAPE_LU_LOAD_MASK		1
+#define IDETAPE_LU_RETENSION_MASK	2
+#define IDETAPE_LU_EOT_MASK		4
+
+/* Structures related to the SELECT SENSE / MODE SENSE packet commands. */
+#define IDETAPE_BLOCK_DESCRIPTOR	0
+#define IDETAPE_CAPABILITIES_PAGE	0x2a
+
+/*
+ * Most of our global data which we need to save even as we leave the driver due
+ * to an interrupt or a timer event is stored in the struct defined below.
+ */
+typedef struct ide_tape_obj {
+	ide_drive_t		*drive;
+	struct ide_driver	*driver;
+	struct gendisk		*disk;
+	struct device		dev;
+
+	/* used by REQ_IDETAPE_{READ,WRITE} requests */
+	struct ide_atapi_pc queued_pc;
+
+	/*
+	 * DSC polling variables.
+	 *
+	 * While polling for DSC we use postponed_rq to postpone the current
+	 * request so that ide.c will be able to service pending requests on the
+	 * other device. Note that at most we will have only one DSC (usually
+	 * data transfer) request in the device request queue.
+	 */
+	bool postponed_rq;
+
+	/* The time in which we started polling for DSC */
+	unsigned long dsc_polling_start;
+	/* Timer used to poll for dsc */
+	struct timer_list dsc_timer;
+	/* Read/Write dsc polling frequency */
+	unsigned long best_dsc_rw_freq;
+	unsigned long dsc_poll_freq;
+	unsigned long dsc_timeout;
+
+	/* Read position information */
+	u8 partition;
+	/* Current block */
+	unsigned int first_frame;
+
+	/* Last error information */
+	u8 sense_key, asc, ascq;
+
+	/* Character device operation */
+	unsigned int minor;
+	/* device name */
+	char name[4];
+	/* Current character device data transfer direction */
+	u8 chrdev_dir;
+
+	/* tape block size, usually 512 or 1024 bytes */
+	unsigned short blk_size;
+	int user_bs_factor;
+
+	/* Copy of the tape's Capabilities and Mechanical Page */
+	u8 caps[20];
+
+	/*
+	 * Active data transfer request parameters.
+	 *
+	 * At most, there is only one ide-tape originated data transfer request
+	 * in the device request queue. This allows ide.c to easily service
+	 * requests from the other device when we postpone our active request.
+	 */
+
+	/* Data buffer size chosen based on the tape's recommendation */
+	int buffer_size;
+	/* Staging buffer of buffer_size bytes */
+	void *buf;
+	/* The read/write cursor */
+	void *cur;
+	/* The number of valid bytes in buf */
+	size_t valid;
+
+	/* Measures average tape speed */
+	unsigned long avg_time;
+	int avg_size;
+	int avg_speed;
+
+	/* the door is currently locked */
+	int door_locked;
+	/* the tape hardware is write protected */
+	char drv_write_prot;
+	/* the tape is write protected (hardware or opened as read-only) */
+	char write_prot;
+} idetape_tape_t;
+
+static DEFINE_MUTEX(ide_tape_mutex);
+static DEFINE_MUTEX(idetape_ref_mutex);
+
+static DEFINE_MUTEX(idetape_chrdev_mutex);
+
+static struct class *idetape_sysfs_class;
+
+static void ide_tape_release(struct device *);
+
+static struct ide_tape_obj *idetape_devs[MAX_HWIFS * MAX_DRIVES];
+
+static struct ide_tape_obj *ide_tape_get(struct gendisk *disk, bool cdev,
+					 unsigned int i)
+{
+	struct ide_tape_obj *tape = NULL;
+
+	mutex_lock(&idetape_ref_mutex);
+
+	if (cdev)
+		tape = idetape_devs[i];
+	else
+		tape = ide_drv_g(disk, ide_tape_obj);
+
+	if (tape) {
+		if (ide_device_get(tape->drive))
+			tape = NULL;
+		else
+			get_device(&tape->dev);
+	}
+
+	mutex_unlock(&idetape_ref_mutex);
+	return tape;
+}
+
+static void ide_tape_put(struct ide_tape_obj *tape)
+{
+	ide_drive_t *drive = tape->drive;
+
+	mutex_lock(&idetape_ref_mutex);
+	put_device(&tape->dev);
+	ide_device_put(drive);
+	mutex_unlock(&idetape_ref_mutex);
+}
+
+/*
+ * called on each failed packet command retry to analyze the request sense. We
+ * currently do not utilize this information.
+ */
+static void idetape_analyze_error(ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct ide_atapi_pc *pc = drive->failed_pc;
+	struct request *rq = drive->hwif->rq;
+	u8 *sense = bio_data(rq->bio);
+
+	tape->sense_key = sense[2] & 0xF;
+	tape->asc       = sense[12];
+	tape->ascq      = sense[13];
+
+	ide_debug_log(IDE_DBG_FUNC,
+		      "cmd: 0x%x, sense key = %x, asc = %x, ascq = %x",
+		      rq->cmd[0], tape->sense_key, tape->asc, tape->ascq);
+
+	/* correct remaining bytes to transfer */
+	if (pc->flags & PC_FLAG_DMA_ERROR)
+		scsi_req(rq)->resid_len = tape->blk_size * get_unaligned_be32(&sense[3]);
+
+	/*
+	 * If error was the result of a zero-length read or write command,
+	 * with sense key=5, asc=0x22, ascq=0, let it slide.  Some drives
+	 * (i.e. Seagate STT3401A Travan) don't support 0-length read/writes.
+	 */
+	if ((pc->c[0] == READ_6 || pc->c[0] == WRITE_6)
+	    /* length == 0 */
+	    && pc->c[4] == 0 && pc->c[3] == 0 && pc->c[2] == 0) {
+		if (tape->sense_key == 5) {
+			/* don't report an error, everything's ok */
+			pc->error = 0;
+			/* don't retry read/write */
+			pc->flags |= PC_FLAG_ABORT;
+		}
+	}
+	if (pc->c[0] == READ_6 && (sense[2] & 0x80)) {
+		pc->error = IDE_DRV_ERROR_FILEMARK;
+		pc->flags |= PC_FLAG_ABORT;
+	}
+	if (pc->c[0] == WRITE_6) {
+		if ((sense[2] & 0x40) || (tape->sense_key == 0xd
+		     && tape->asc == 0x0 && tape->ascq == 0x2)) {
+			pc->error = IDE_DRV_ERROR_EOD;
+			pc->flags |= PC_FLAG_ABORT;
+		}
+	}
+	if (pc->c[0] == READ_6 || pc->c[0] == WRITE_6) {
+		if (tape->sense_key == 8) {
+			pc->error = IDE_DRV_ERROR_EOD;
+			pc->flags |= PC_FLAG_ABORT;
+		}
+		if (!(pc->flags & PC_FLAG_ABORT) &&
+		    (blk_rq_bytes(rq) - scsi_req(rq)->resid_len))
+			pc->retries = IDETAPE_MAX_PC_RETRIES + 1;
+	}
+}
+
+static void ide_tape_handle_dsc(ide_drive_t *);
+
+static int ide_tape_callback(ide_drive_t *drive, int dsc)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct ide_atapi_pc *pc = drive->pc;
+	struct request *rq = drive->hwif->rq;
+	int uptodate = pc->error ? 0 : 1;
+	int err = uptodate ? 0 : IDE_DRV_ERROR_GENERAL;
+
+	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x, dsc: %d, err: %d", rq->cmd[0],
+		      dsc, err);
+
+	if (dsc)
+		ide_tape_handle_dsc(drive);
+
+	if (drive->failed_pc == pc)
+		drive->failed_pc = NULL;
+
+	if (pc->c[0] == REQUEST_SENSE) {
+		if (uptodate)
+			idetape_analyze_error(drive);
+		else
+			printk(KERN_ERR "ide-tape: Error in REQUEST SENSE "
+					"itself - Aborting request!\n");
+	} else if (pc->c[0] == READ_6 || pc->c[0] == WRITE_6) {
+		unsigned int blocks =
+			(blk_rq_bytes(rq) - scsi_req(rq)->resid_len) / tape->blk_size;
+
+		tape->avg_size += blocks * tape->blk_size;
+
+		if (time_after_eq(jiffies, tape->avg_time + HZ)) {
+			tape->avg_speed = tape->avg_size * HZ /
+				(jiffies - tape->avg_time) / 1024;
+			tape->avg_size = 0;
+			tape->avg_time = jiffies;
+		}
+
+		tape->first_frame += blocks;
+
+		if (pc->error) {
+			uptodate = 0;
+			err = pc->error;
+		}
+	}
+	scsi_req(rq)->result = err;
+
+	return uptodate;
+}
+
+/*
+ * Postpone the current request so that ide.c will be able to service requests
+ * from another device on the same port while we are polling for DSC.
+ */
+static void ide_tape_stall_queue(ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x, dsc_poll_freq: %lu",
+		      drive->hwif->rq->cmd[0], tape->dsc_poll_freq);
+
+	tape->postponed_rq = true;
+
+	ide_stall_queue(drive, tape->dsc_poll_freq);
+}
+
+static void ide_tape_handle_dsc(ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+	/* Media access command */
+	tape->dsc_polling_start = jiffies;
+	tape->dsc_poll_freq = IDETAPE_DSC_MA_FAST;
+	tape->dsc_timeout = jiffies + IDETAPE_DSC_MA_TIMEOUT;
+	/* Allow ide.c to handle other requests */
+	ide_tape_stall_queue(drive);
+}
+
+/*
+ * Packet Command Interface
+ *
+ * The current Packet Command is available in drive->pc, and will not change
+ * until we finish handling it. Each packet command is associated with a
+ * callback function that will be called when the command is finished.
+ *
+ * The handling will be done in three stages:
+ *
+ * 1. ide_tape_issue_pc will send the packet command to the drive, and will set
+ * the interrupt handler to ide_pc_intr.
+ *
+ * 2. On each interrupt, ide_pc_intr will be called. This step will be
+ * repeated until the device signals us that no more interrupts will be issued.
+ *
+ * 3. ATAPI Tape media access commands have immediate status with a delayed
+ * process. In case of a successful initiation of a media access packet command,
+ * the DSC bit will be set when the actual execution of the command is finished.
+ * Since the tape drive will not issue an interrupt, we have to poll for this
+ * event. In this case, we define the request as "low priority request" by
+ * setting rq_status to IDETAPE_RQ_POSTPONED, set a timer to poll for DSC and
+ * exit the driver.
+ *
+ * ide.c will then give higher priority to requests which originate from the
+ * other device, until will change rq_status to RQ_ACTIVE.
+ *
+ * 4. When the packet command is finished, it will be checked for errors.
+ *
+ * 5. In case an error was found, we queue a request sense packet command in
+ * front of the request queue and retry the operation up to
+ * IDETAPE_MAX_PC_RETRIES times.
+ *
+ * 6. In case no error was found, or we decided to give up and not to retry
+ * again, the callback function will be called and then we will handle the next
+ * request.
+ */
+
+static ide_startstop_t ide_tape_issue_pc(ide_drive_t *drive,
+					 struct ide_cmd *cmd,
+					 struct ide_atapi_pc *pc)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct request *rq = drive->hwif->rq;
+
+	if (drive->failed_pc == NULL && pc->c[0] != REQUEST_SENSE)
+		drive->failed_pc = pc;
+
+	/* Set the current packet command */
+	drive->pc = pc;
+
+	if (pc->retries > IDETAPE_MAX_PC_RETRIES ||
+		(pc->flags & PC_FLAG_ABORT)) {
+
+		/*
+		 * We will "abort" retrying a packet command in case legitimate
+		 * error code was received (crossing a filemark, or end of the
+		 * media, for example).
+		 */
+		if (!(pc->flags & PC_FLAG_ABORT)) {
+			if (!(pc->c[0] == TEST_UNIT_READY &&
+			      tape->sense_key == 2 && tape->asc == 4 &&
+			     (tape->ascq == 1 || tape->ascq == 8))) {
+				printk(KERN_ERR "ide-tape: %s: I/O error, "
+						"pc = %2x, key = %2x, "
+						"asc = %2x, ascq = %2x\n",
+						tape->name, pc->c[0],
+						tape->sense_key, tape->asc,
+						tape->ascq);
+			}
+			/* Giving up */
+			pc->error = IDE_DRV_ERROR_GENERAL;
+		}
+
+		drive->failed_pc = NULL;
+		drive->pc_callback(drive, 0);
+		ide_complete_rq(drive, BLK_STS_IOERR, blk_rq_bytes(rq));
+		return ide_stopped;
+	}
+	ide_debug_log(IDE_DBG_SENSE, "retry #%d, cmd: 0x%02x", pc->retries,
+		      pc->c[0]);
+
+	pc->retries++;
+
+	return ide_issue_pc(drive, cmd);
+}
+
+/* A mode sense command is used to "sense" tape parameters. */
+static void idetape_create_mode_sense_cmd(struct ide_atapi_pc *pc, u8 page_code)
+{
+	ide_init_pc(pc);
+	pc->c[0] = MODE_SENSE;
+	if (page_code != IDETAPE_BLOCK_DESCRIPTOR)
+		/* DBD = 1 - Don't return block descriptors */
+		pc->c[1] = 8;
+	pc->c[2] = page_code;
+	/*
+	 * Changed pc->c[3] to 0 (255 will at best return unused info).
+	 *
+	 * For SCSI this byte is defined as subpage instead of high byte
+	 * of length and some IDE drives seem to interpret it this way
+	 * and return an error when 255 is used.
+	 */
+	pc->c[3] = 0;
+	/* We will just discard data in that case */
+	pc->c[4] = 255;
+	if (page_code == IDETAPE_BLOCK_DESCRIPTOR)
+		pc->req_xfer = 12;
+	else if (page_code == IDETAPE_CAPABILITIES_PAGE)
+		pc->req_xfer = 24;
+	else
+		pc->req_xfer = 50;
+}
+
+static ide_startstop_t idetape_media_access_finished(ide_drive_t *drive)
+{
+	ide_hwif_t *hwif = drive->hwif;
+	idetape_tape_t *tape = drive->driver_data;
+	struct ide_atapi_pc *pc = drive->pc;
+	u8 stat;
+
+	stat = hwif->tp_ops->read_status(hwif);
+
+	if (stat & ATA_DSC) {
+		if (stat & ATA_ERR) {
+			/* Error detected */
+			if (pc->c[0] != TEST_UNIT_READY)
+				printk(KERN_ERR "ide-tape: %s: I/O error, ",
+						tape->name);
+			/* Retry operation */
+			ide_retry_pc(drive);
+			return ide_stopped;
+		}
+		pc->error = 0;
+	} else {
+		pc->error = IDE_DRV_ERROR_GENERAL;
+		drive->failed_pc = NULL;
+	}
+	drive->pc_callback(drive, 0);
+	return ide_stopped;
+}
+
+static void ide_tape_create_rw_cmd(idetape_tape_t *tape,
+				   struct ide_atapi_pc *pc, struct request *rq,
+				   u8 opcode)
+{
+	unsigned int length = blk_rq_sectors(rq) / (tape->blk_size >> 9);
+
+	ide_init_pc(pc);
+	put_unaligned(cpu_to_be32(length), (unsigned int *) &pc->c[1]);
+	pc->c[1] = 1;
+
+	if (blk_rq_bytes(rq) == tape->buffer_size)
+		pc->flags |= PC_FLAG_DMA_OK;
+
+	if (opcode == READ_6)
+		pc->c[0] = READ_6;
+	else if (opcode == WRITE_6) {
+		pc->c[0] = WRITE_6;
+		pc->flags |= PC_FLAG_WRITING;
+	}
+
+	memcpy(scsi_req(rq)->cmd, pc->c, 12);
+}
+
+static ide_startstop_t idetape_do_request(ide_drive_t *drive,
+					  struct request *rq, sector_t block)
+{
+	ide_hwif_t *hwif = drive->hwif;
+	idetape_tape_t *tape = drive->driver_data;
+	struct ide_atapi_pc *pc = NULL;
+	struct ide_cmd cmd;
+	struct scsi_request *req = scsi_req(rq);
+	u8 stat;
+
+	ide_debug_log(IDE_DBG_RQ, "cmd: 0x%x, sector: %llu, nr_sectors: %u",
+		      req->cmd[0], (unsigned long long)blk_rq_pos(rq),
+		      blk_rq_sectors(rq));
+
+	BUG_ON(!blk_rq_is_private(rq));
+	BUG_ON(ide_req(rq)->type != ATA_PRIV_MISC &&
+	       ide_req(rq)->type != ATA_PRIV_SENSE);
+
+	/* Retry a failed packet command */
+	if (drive->failed_pc && drive->pc->c[0] == REQUEST_SENSE) {
+		pc = drive->failed_pc;
+		goto out;
+	}
+
+	/*
+	 * If the tape is still busy, postpone our request and service
+	 * the other device meanwhile.
+	 */
+	stat = hwif->tp_ops->read_status(hwif);
+
+	if ((drive->dev_flags & IDE_DFLAG_DSC_OVERLAP) == 0 &&
+	    (req->cmd[13] & REQ_IDETAPE_PC2) == 0)
+		drive->atapi_flags |= IDE_AFLAG_IGNORE_DSC;
+
+	if (drive->dev_flags & IDE_DFLAG_POST_RESET) {
+		drive->atapi_flags |= IDE_AFLAG_IGNORE_DSC;
+		drive->dev_flags &= ~IDE_DFLAG_POST_RESET;
+	}
+
+	if (!(drive->atapi_flags & IDE_AFLAG_IGNORE_DSC) &&
+	    !(stat & ATA_DSC)) {
+		if (!tape->postponed_rq) {
+			tape->dsc_polling_start = jiffies;
+			tape->dsc_poll_freq = tape->best_dsc_rw_freq;
+			tape->dsc_timeout = jiffies + IDETAPE_DSC_RW_TIMEOUT;
+		} else if (time_after(jiffies, tape->dsc_timeout)) {
+			printk(KERN_ERR "ide-tape: %s: DSC timeout\n",
+				tape->name);
+			if (req->cmd[13] & REQ_IDETAPE_PC2) {
+				idetape_media_access_finished(drive);
+				return ide_stopped;
+			} else {
+				return ide_do_reset(drive);
+			}
+		} else if (time_after(jiffies,
+					tape->dsc_polling_start +
+					IDETAPE_DSC_MA_THRESHOLD))
+			tape->dsc_poll_freq = IDETAPE_DSC_MA_SLOW;
+		ide_tape_stall_queue(drive);
+		return ide_stopped;
+	} else {
+		drive->atapi_flags &= ~IDE_AFLAG_IGNORE_DSC;
+		tape->postponed_rq = false;
+	}
+
+	if (req->cmd[13] & REQ_IDETAPE_READ) {
+		pc = &tape->queued_pc;
+		ide_tape_create_rw_cmd(tape, pc, rq, READ_6);
+		goto out;
+	}
+	if (req->cmd[13] & REQ_IDETAPE_WRITE) {
+		pc = &tape->queued_pc;
+		ide_tape_create_rw_cmd(tape, pc, rq, WRITE_6);
+		goto out;
+	}
+	if (req->cmd[13] & REQ_IDETAPE_PC1) {
+		pc = (struct ide_atapi_pc *)ide_req(rq)->special;
+		req->cmd[13] &= ~(REQ_IDETAPE_PC1);
+		req->cmd[13] |= REQ_IDETAPE_PC2;
+		goto out;
+	}
+	if (req->cmd[13] & REQ_IDETAPE_PC2) {
+		idetape_media_access_finished(drive);
+		return ide_stopped;
+	}
+	BUG();
+
+out:
+	/* prepare sense request for this command */
+	ide_prep_sense(drive, rq);
+
+	memset(&cmd, 0, sizeof(cmd));
+
+	if (rq_data_dir(rq))
+		cmd.tf_flags |= IDE_TFLAG_WRITE;
+
+	cmd.rq = rq;
+
+	ide_init_sg_cmd(&cmd, blk_rq_bytes(rq));
+	ide_map_sg(drive, &cmd);
+
+	return ide_tape_issue_pc(drive, &cmd, pc);
+}
+
+/*
+ * Write a filemark if write_filemark=1. Flush the device buffers without
+ * writing a filemark otherwise.
+ */
+static void idetape_create_write_filemark_cmd(ide_drive_t *drive,
+		struct ide_atapi_pc *pc, int write_filemark)
+{
+	ide_init_pc(pc);
+	pc->c[0] = WRITE_FILEMARKS;
+	pc->c[4] = write_filemark;
+	pc->flags |= PC_FLAG_WAIT_FOR_DSC;
+}
+
+static int idetape_wait_ready(ide_drive_t *drive, unsigned long timeout)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct gendisk *disk = tape->disk;
+	int load_attempted = 0;
+
+	/* Wait for the tape to become ready */
+	set_bit(ilog2(IDE_AFLAG_MEDIUM_PRESENT), &drive->atapi_flags);
+	timeout += jiffies;
+	while (time_before(jiffies, timeout)) {
+		if (ide_do_test_unit_ready(drive, disk) == 0)
+			return 0;
+		if ((tape->sense_key == 2 && tape->asc == 4 && tape->ascq == 2)
+		    || (tape->asc == 0x3A)) {
+			/* no media */
+			if (load_attempted)
+				return -ENOMEDIUM;
+			ide_do_start_stop(drive, disk, IDETAPE_LU_LOAD_MASK);
+			load_attempted = 1;
+		/* not about to be ready */
+		} else if (!(tape->sense_key == 2 && tape->asc == 4 &&
+			     (tape->ascq == 1 || tape->ascq == 8)))
+			return -EIO;
+		msleep(100);
+	}
+	return -EIO;
+}
+
+static int idetape_flush_tape_buffers(ide_drive_t *drive)
+{
+	struct ide_tape_obj *tape = drive->driver_data;
+	struct ide_atapi_pc pc;
+	int rc;
+
+	idetape_create_write_filemark_cmd(drive, &pc, 0);
+	rc = ide_queue_pc_tail(drive, tape->disk, &pc, NULL, 0);
+	if (rc)
+		return rc;
+	idetape_wait_ready(drive, 60 * 5 * HZ);
+	return 0;
+}
+
+static int ide_tape_read_position(ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct ide_atapi_pc pc;
+	u8 buf[20];
+
+	ide_debug_log(IDE_DBG_FUNC, "enter");
+
+	/* prep cmd */
+	ide_init_pc(&pc);
+	pc.c[0] = READ_POSITION;
+	pc.req_xfer = 20;
+
+	if (ide_queue_pc_tail(drive, tape->disk, &pc, buf, pc.req_xfer))
+		return -1;
+
+	if (!pc.error) {
+		ide_debug_log(IDE_DBG_FUNC, "BOP - %s",
+				(buf[0] & 0x80) ? "Yes" : "No");
+		ide_debug_log(IDE_DBG_FUNC, "EOP - %s",
+				(buf[0] & 0x40) ? "Yes" : "No");
+
+		if (buf[0] & 0x4) {
+			printk(KERN_INFO "ide-tape: Block location is unknown"
+					 "to the tape\n");
+			clear_bit(ilog2(IDE_AFLAG_ADDRESS_VALID),
+				  &drive->atapi_flags);
+			return -1;
+		} else {
+			ide_debug_log(IDE_DBG_FUNC, "Block Location: %u",
+				      be32_to_cpup((__be32 *)&buf[4]));
+
+			tape->partition = buf[1];
+			tape->first_frame = be32_to_cpup((__be32 *)&buf[4]);
+			set_bit(ilog2(IDE_AFLAG_ADDRESS_VALID),
+				&drive->atapi_flags);
+		}
+	}
+
+	return tape->first_frame;
+}
+
+static void idetape_create_locate_cmd(ide_drive_t *drive,
+		struct ide_atapi_pc *pc,
+		unsigned int block, u8 partition, int skip)
+{
+	ide_init_pc(pc);
+	pc->c[0] = POSITION_TO_ELEMENT;
+	pc->c[1] = 2;
+	put_unaligned(cpu_to_be32(block), (unsigned int *) &pc->c[3]);
+	pc->c[8] = partition;
+	pc->flags |= PC_FLAG_WAIT_FOR_DSC;
+}
+
+static void __ide_tape_discard_merge_buffer(ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+	if (tape->chrdev_dir != IDETAPE_DIR_READ)
+		return;
+
+	clear_bit(ilog2(IDE_AFLAG_FILEMARK), &drive->atapi_flags);
+	tape->valid = 0;
+	if (tape->buf != NULL) {
+		kfree(tape->buf);
+		tape->buf = NULL;
+	}
+
+	tape->chrdev_dir = IDETAPE_DIR_NONE;
+}
+
+/*
+ * Position the tape to the requested block using the LOCATE packet command.
+ * A READ POSITION command is then issued to check where we are positioned. Like
+ * all higher level operations, we queue the commands at the tail of the request
+ * queue and wait for their completion.
+ */
+static int idetape_position_tape(ide_drive_t *drive, unsigned int block,
+		u8 partition, int skip)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct gendisk *disk = tape->disk;
+	int ret;
+	struct ide_atapi_pc pc;
+
+	if (tape->chrdev_dir == IDETAPE_DIR_READ)
+		__ide_tape_discard_merge_buffer(drive);
+	idetape_wait_ready(drive, 60 * 5 * HZ);
+	idetape_create_locate_cmd(drive, &pc, block, partition, skip);
+	ret = ide_queue_pc_tail(drive, disk, &pc, NULL, 0);
+	if (ret)
+		return ret;
+
+	ret = ide_tape_read_position(drive);
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+static void ide_tape_discard_merge_buffer(ide_drive_t *drive,
+					  int restore_position)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	int seek, position;
+
+	__ide_tape_discard_merge_buffer(drive);
+	if (restore_position) {
+		position = ide_tape_read_position(drive);
+		seek = position > 0 ? position : 0;
+		if (idetape_position_tape(drive, seek, 0, 0)) {
+			printk(KERN_INFO "ide-tape: %s: position_tape failed in"
+					 " %s\n", tape->name, __func__);
+			return;
+		}
+	}
+}
+
+/*
+ * Generate a read/write request for the block device interface and wait for it
+ * to be serviced.
+ */
+static int idetape_queue_rw_tail(ide_drive_t *drive, int cmd, int size)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct request *rq;
+	int ret;
+
+	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x, size: %d", cmd, size);
+
+	BUG_ON(cmd != REQ_IDETAPE_READ && cmd != REQ_IDETAPE_WRITE);
+	BUG_ON(size < 0 || size % tape->blk_size);
+
+	rq = blk_get_request(drive->queue, REQ_OP_DRV_IN, 0);
+	ide_req(rq)->type = ATA_PRIV_MISC;
+	scsi_req(rq)->cmd[13] = cmd;
+	rq->rq_disk = tape->disk;
+	rq->__sector = tape->first_frame;
+
+	if (size) {
+		ret = blk_rq_map_kern(drive->queue, rq, tape->buf, size,
+				      GFP_NOIO);
+		if (ret)
+			goto out_put;
+	}
+
+	blk_execute_rq(drive->queue, tape->disk, rq, 0);
+
+	/* calculate the number of transferred bytes and update buffer state */
+	size -= scsi_req(rq)->resid_len;
+	tape->cur = tape->buf;
+	if (cmd == REQ_IDETAPE_READ)
+		tape->valid = size;
+	else
+		tape->valid = 0;
+
+	ret = size;
+	if (scsi_req(rq)->result == IDE_DRV_ERROR_GENERAL)
+		ret = -EIO;
+out_put:
+	blk_put_request(rq);
+	return ret;
+}
+
+static void idetape_create_inquiry_cmd(struct ide_atapi_pc *pc)
+{
+	ide_init_pc(pc);
+	pc->c[0] = INQUIRY;
+	pc->c[4] = 254;
+	pc->req_xfer = 254;
+}
+
+static void idetape_create_rewind_cmd(ide_drive_t *drive,
+		struct ide_atapi_pc *pc)
+{
+	ide_init_pc(pc);
+	pc->c[0] = REZERO_UNIT;
+	pc->flags |= PC_FLAG_WAIT_FOR_DSC;
+}
+
+static void idetape_create_erase_cmd(struct ide_atapi_pc *pc)
+{
+	ide_init_pc(pc);
+	pc->c[0] = ERASE;
+	pc->c[1] = 1;
+	pc->flags |= PC_FLAG_WAIT_FOR_DSC;
+}
+
+static void idetape_create_space_cmd(struct ide_atapi_pc *pc, int count, u8 cmd)
+{
+	ide_init_pc(pc);
+	pc->c[0] = SPACE;
+	put_unaligned(cpu_to_be32(count), (unsigned int *) &pc->c[1]);
+	pc->c[1] = cmd;
+	pc->flags |= PC_FLAG_WAIT_FOR_DSC;
+}
+
+static void ide_tape_flush_merge_buffer(ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+	if (tape->chrdev_dir != IDETAPE_DIR_WRITE) {
+		printk(KERN_ERR "ide-tape: bug: Trying to empty merge buffer"
+				" but we are not writing.\n");
+		return;
+	}
+	if (tape->buf) {
+		size_t aligned = roundup(tape->valid, tape->blk_size);
+
+		memset(tape->cur, 0, aligned - tape->valid);
+		idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, aligned);
+		kfree(tape->buf);
+		tape->buf = NULL;
+	}
+	tape->chrdev_dir = IDETAPE_DIR_NONE;
+}
+
+static int idetape_init_rw(ide_drive_t *drive, int dir)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	int rc;
+
+	BUG_ON(dir != IDETAPE_DIR_READ && dir != IDETAPE_DIR_WRITE);
+
+	if (tape->chrdev_dir == dir)
+		return 0;
+
+	if (tape->chrdev_dir == IDETAPE_DIR_READ)
+		ide_tape_discard_merge_buffer(drive, 1);
+	else if (tape->chrdev_dir == IDETAPE_DIR_WRITE) {
+		ide_tape_flush_merge_buffer(drive);
+		idetape_flush_tape_buffers(drive);
+	}
+
+	if (tape->buf || tape->valid) {
+		printk(KERN_ERR "ide-tape: valid should be 0 now\n");
+		tape->valid = 0;
+	}
+
+	tape->buf = kmalloc(tape->buffer_size, GFP_KERNEL);
+	if (!tape->buf)
+		return -ENOMEM;
+	tape->chrdev_dir = dir;
+	tape->cur = tape->buf;
+
+	/*
+	 * Issue a 0 rw command to ensure that DSC handshake is
+	 * switched from completion mode to buffer available mode.  No
+	 * point in issuing this if DSC overlap isn't supported, some
+	 * drives (Seagate STT3401A) will return an error.
+	 */
+	if (drive->dev_flags & IDE_DFLAG_DSC_OVERLAP) {
+		int cmd = dir == IDETAPE_DIR_READ ? REQ_IDETAPE_READ
+						  : REQ_IDETAPE_WRITE;
+
+		rc = idetape_queue_rw_tail(drive, cmd, 0);
+		if (rc < 0) {
+			kfree(tape->buf);
+			tape->buf = NULL;
+			tape->chrdev_dir = IDETAPE_DIR_NONE;
+			return rc;
+		}
+	}
+
+	return 0;
+}
+
+static void idetape_pad_zeros(ide_drive_t *drive, int bcount)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+	memset(tape->buf, 0, tape->buffer_size);
+
+	while (bcount) {
+		unsigned int count = min(tape->buffer_size, bcount);
+
+		idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, count);
+		bcount -= count;
+	}
+}
+
+/*
+ * Rewinds the tape to the Beginning Of the current Partition (BOP). We
+ * currently support only one partition.
+ */
+static int idetape_rewind_tape(ide_drive_t *drive)
+{
+	struct ide_tape_obj *tape = drive->driver_data;
+	struct gendisk *disk = tape->disk;
+	struct ide_atapi_pc pc;
+	int ret;
+
+	ide_debug_log(IDE_DBG_FUNC, "enter");
+
+	idetape_create_rewind_cmd(drive, &pc);
+	ret = ide_queue_pc_tail(drive, disk, &pc, NULL, 0);
+	if (ret)
+		return ret;
+
+	ret = ide_tape_read_position(drive);
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+/* mtio.h compatible commands should be issued to the chrdev interface. */
+static int idetape_blkdev_ioctl(ide_drive_t *drive, unsigned int cmd,
+				unsigned long arg)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	void __user *argp = (void __user *)arg;
+
+	struct idetape_config {
+		int dsc_rw_frequency;
+		int dsc_media_access_frequency;
+		int nr_stages;
+	} config;
+
+	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%04x", cmd);
+
+	switch (cmd) {
+	case 0x0340:
+		if (copy_from_user(&config, argp, sizeof(config)))
+			return -EFAULT;
+		tape->best_dsc_rw_freq = config.dsc_rw_frequency;
+		break;
+	case 0x0350:
+		memset(&config, 0, sizeof(config));
+		config.dsc_rw_frequency = (int) tape->best_dsc_rw_freq;
+		config.nr_stages = 1;
+		if (copy_to_user(argp, &config, sizeof(config)))
+			return -EFAULT;
+		break;
+	default:
+		return -EIO;
+	}
+	return 0;
+}
+
+static int idetape_space_over_filemarks(ide_drive_t *drive, short mt_op,
+					int mt_count)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct gendisk *disk = tape->disk;
+	struct ide_atapi_pc pc;
+	int retval, count = 0;
+	int sprev = !!(tape->caps[4] & 0x20);
+
+
+	ide_debug_log(IDE_DBG_FUNC, "mt_op: %d, mt_count: %d", mt_op, mt_count);
+
+	if (mt_count == 0)
+		return 0;
+	if (MTBSF == mt_op || MTBSFM == mt_op) {
+		if (!sprev)
+			return -EIO;
+		mt_count = -mt_count;
+	}
+
+	if (tape->chrdev_dir == IDETAPE_DIR_READ) {
+		tape->valid = 0;
+		if (test_and_clear_bit(ilog2(IDE_AFLAG_FILEMARK),
+				       &drive->atapi_flags))
+			++count;
+		ide_tape_discard_merge_buffer(drive, 0);
+	}
+
+	switch (mt_op) {
+	case MTFSF:
+	case MTBSF:
+		idetape_create_space_cmd(&pc, mt_count - count,
+					 IDETAPE_SPACE_OVER_FILEMARK);
+		return ide_queue_pc_tail(drive, disk, &pc, NULL, 0);
+	case MTFSFM:
+	case MTBSFM:
+		if (!sprev)
+			return -EIO;
+		retval = idetape_space_over_filemarks(drive, MTFSF,
+						      mt_count - count);
+		if (retval)
+			return retval;
+		count = (MTBSFM == mt_op ? 1 : -1);
+		return idetape_space_over_filemarks(drive, MTFSF, count);
+	default:
+		printk(KERN_ERR "ide-tape: MTIO operation %d not supported\n",
+				mt_op);
+		return -EIO;
+	}
+}
+
+/*
+ * Our character device read / write functions.
+ *
+ * The tape is optimized to maximize throughput when it is transferring an
+ * integral number of the "continuous transfer limit", which is a parameter of
+ * the specific tape (26kB on my particular tape, 32kB for Onstream).
+ *
+ * As of version 1.3 of the driver, the character device provides an abstract
+ * continuous view of the media - any mix of block sizes (even 1 byte) on the
+ * same backup/restore procedure is supported. The driver will internally
+ * convert the requests to the recommended transfer unit, so that an unmatch
+ * between the user's block size to the recommended size will only result in a
+ * (slightly) increased driver overhead, but will no longer hit performance.
+ * This is not applicable to Onstream.
+ */
+static ssize_t idetape_chrdev_read(struct file *file, char __user *buf,
+				   size_t count, loff_t *ppos)
+{
+	struct ide_tape_obj *tape = file->private_data;
+	ide_drive_t *drive = tape->drive;
+	size_t done = 0;
+	ssize_t ret = 0;
+	int rc;
+
+	ide_debug_log(IDE_DBG_FUNC, "count %zd", count);
+
+	if (tape->chrdev_dir != IDETAPE_DIR_READ) {
+		if (test_bit(ilog2(IDE_AFLAG_DETECT_BS), &drive->atapi_flags))
+			if (count > tape->blk_size &&
+			    (count % tape->blk_size) == 0)
+				tape->user_bs_factor = count / tape->blk_size;
+	}
+
+	rc = idetape_init_rw(drive, IDETAPE_DIR_READ);
+	if (rc < 0)
+		return rc;
+
+	while (done < count) {
+		size_t todo;
+
+		/* refill if staging buffer is empty */
+		if (!tape->valid) {
+			/* If we are at a filemark, nothing more to read */
+			if (test_bit(ilog2(IDE_AFLAG_FILEMARK),
+				     &drive->atapi_flags))
+				break;
+			/* read */
+			if (idetape_queue_rw_tail(drive, REQ_IDETAPE_READ,
+						  tape->buffer_size) <= 0)
+				break;
+		}
+
+		/* copy out */
+		todo = min_t(size_t, count - done, tape->valid);
+		if (copy_to_user(buf + done, tape->cur, todo))
+			ret = -EFAULT;
+
+		tape->cur += todo;
+		tape->valid -= todo;
+		done += todo;
+	}
+
+	if (!done && test_bit(ilog2(IDE_AFLAG_FILEMARK), &drive->atapi_flags)) {
+		idetape_space_over_filemarks(drive, MTFSF, 1);
+		return 0;
+	}
+
+	return ret ? ret : done;
+}
+
+static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
+				     size_t count, loff_t *ppos)
+{
+	struct ide_tape_obj *tape = file->private_data;
+	ide_drive_t *drive = tape->drive;
+	size_t done = 0;
+	ssize_t ret = 0;
+	int rc;
+
+	/* The drive is write protected. */
+	if (tape->write_prot)
+		return -EACCES;
+
+	ide_debug_log(IDE_DBG_FUNC, "count %zd", count);
+
+	/* Initialize write operation */
+	rc = idetape_init_rw(drive, IDETAPE_DIR_WRITE);
+	if (rc < 0)
+		return rc;
+
+	while (done < count) {
+		size_t todo;
+
+		/* flush if staging buffer is full */
+		if (tape->valid == tape->buffer_size &&
+		    idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE,
+					  tape->buffer_size) <= 0)
+			return rc;
+
+		/* copy in */
+		todo = min_t(size_t, count - done,
+			     tape->buffer_size - tape->valid);
+		if (copy_from_user(tape->cur, buf + done, todo))
+			ret = -EFAULT;
+
+		tape->cur += todo;
+		tape->valid += todo;
+		done += todo;
+	}
+
+	return ret ? ret : done;
+}
+
+static int idetape_write_filemark(ide_drive_t *drive)
+{
+	struct ide_tape_obj *tape = drive->driver_data;
+	struct ide_atapi_pc pc;
+
+	/* Write a filemark */
+	idetape_create_write_filemark_cmd(drive, &pc, 1);
+	if (ide_queue_pc_tail(drive, tape->disk, &pc, NULL, 0)) {
+		printk(KERN_ERR "ide-tape: Couldn't write a filemark\n");
+		return -EIO;
+	}
+	return 0;
+}
+
+/*
+ * Called from idetape_chrdev_ioctl when the general mtio MTIOCTOP ioctl is
+ * requested.
+ *
+ * Note: MTBSF and MTBSFM are not supported when the tape doesn't support
+ * spacing over filemarks in the reverse direction. In this case, MTFSFM is also
+ * usually not supported.
+ *
+ * The following commands are currently not supported:
+ *
+ * MTFSS, MTBSS, MTWSM, MTSETDENSITY, MTSETDRVBUFFER, MT_ST_BOOLEANS,
+ * MT_ST_WRITE_THRESHOLD.
+ */
+static int idetape_mtioctop(ide_drive_t *drive, short mt_op, int mt_count)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct gendisk *disk = tape->disk;
+	struct ide_atapi_pc pc;
+	int i, retval;
+
+	ide_debug_log(IDE_DBG_FUNC, "MTIOCTOP ioctl: mt_op: %d, mt_count: %d",
+		      mt_op, mt_count);
+
+	switch (mt_op) {
+	case MTFSF:
+	case MTFSFM:
+	case MTBSF:
+	case MTBSFM:
+		if (!mt_count)
+			return 0;
+		return idetape_space_over_filemarks(drive, mt_op, mt_count);
+	default:
+		break;
+	}
+
+	switch (mt_op) {
+	case MTWEOF:
+		if (tape->write_prot)
+			return -EACCES;
+		ide_tape_discard_merge_buffer(drive, 1);
+		for (i = 0; i < mt_count; i++) {
+			retval = idetape_write_filemark(drive);
+			if (retval)
+				return retval;
+		}
+		return 0;
+	case MTREW:
+		ide_tape_discard_merge_buffer(drive, 0);
+		if (idetape_rewind_tape(drive))
+			return -EIO;
+		return 0;
+	case MTLOAD:
+		ide_tape_discard_merge_buffer(drive, 0);
+		return ide_do_start_stop(drive, disk, IDETAPE_LU_LOAD_MASK);
+	case MTUNLOAD:
+	case MTOFFL:
+		/*
+		 * If door is locked, attempt to unlock before
+		 * attempting to eject.
+		 */
+		if (tape->door_locked) {
+			if (!ide_set_media_lock(drive, disk, 0))
+				tape->door_locked = DOOR_UNLOCKED;
+		}
+		ide_tape_discard_merge_buffer(drive, 0);
+		retval = ide_do_start_stop(drive, disk, !IDETAPE_LU_LOAD_MASK);
+		if (!retval)
+			clear_bit(ilog2(IDE_AFLAG_MEDIUM_PRESENT),
+				  &drive->atapi_flags);
+		return retval;
+	case MTNOP:
+		ide_tape_discard_merge_buffer(drive, 0);
+		return idetape_flush_tape_buffers(drive);
+	case MTRETEN:
+		ide_tape_discard_merge_buffer(drive, 0);
+		return ide_do_start_stop(drive, disk,
+			IDETAPE_LU_RETENSION_MASK | IDETAPE_LU_LOAD_MASK);
+	case MTEOM:
+		idetape_create_space_cmd(&pc, 0, IDETAPE_SPACE_TO_EOD);
+		return ide_queue_pc_tail(drive, disk, &pc, NULL, 0);
+	case MTERASE:
+		(void)idetape_rewind_tape(drive);
+		idetape_create_erase_cmd(&pc);
+		return ide_queue_pc_tail(drive, disk, &pc, NULL, 0);
+	case MTSETBLK:
+		if (mt_count) {
+			if (mt_count < tape->blk_size ||
+			    mt_count % tape->blk_size)
+				return -EIO;
+			tape->user_bs_factor = mt_count / tape->blk_size;
+			clear_bit(ilog2(IDE_AFLAG_DETECT_BS),
+				  &drive->atapi_flags);
+		} else
+			set_bit(ilog2(IDE_AFLAG_DETECT_BS),
+				&drive->atapi_flags);
+		return 0;
+	case MTSEEK:
+		ide_tape_discard_merge_buffer(drive, 0);
+		return idetape_position_tape(drive,
+			mt_count * tape->user_bs_factor, tape->partition, 0);
+	case MTSETPART:
+		ide_tape_discard_merge_buffer(drive, 0);
+		return idetape_position_tape(drive, 0, mt_count, 0);
+	case MTFSR:
+	case MTBSR:
+	case MTLOCK:
+		retval = ide_set_media_lock(drive, disk, 1);
+		if (retval)
+			return retval;
+		tape->door_locked = DOOR_EXPLICITLY_LOCKED;
+		return 0;
+	case MTUNLOCK:
+		retval = ide_set_media_lock(drive, disk, 0);
+		if (retval)
+			return retval;
+		tape->door_locked = DOOR_UNLOCKED;
+		return 0;
+	default:
+		printk(KERN_ERR "ide-tape: MTIO operation %d not supported\n",
+				mt_op);
+		return -EIO;
+	}
+}
+
+/*
+ * Our character device ioctls. General mtio.h magnetic io commands are
+ * supported here, and not in the corresponding block interface. Our own
+ * ide-tape ioctls are supported on both interfaces.
+ */
+static long do_idetape_chrdev_ioctl(struct file *file,
+				unsigned int cmd, unsigned long arg)
+{
+	struct ide_tape_obj *tape = file->private_data;
+	ide_drive_t *drive = tape->drive;
+	struct mtop mtop;
+	struct mtget mtget;
+	struct mtpos mtpos;
+	int block_offset = 0, position = tape->first_frame;
+	void __user *argp = (void __user *)arg;
+
+	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x", cmd);
+
+	if (tape->chrdev_dir == IDETAPE_DIR_WRITE) {
+		ide_tape_flush_merge_buffer(drive);
+		idetape_flush_tape_buffers(drive);
+	}
+	if (cmd == MTIOCGET || cmd == MTIOCPOS) {
+		block_offset = tape->valid /
+			(tape->blk_size * tape->user_bs_factor);
+		position = ide_tape_read_position(drive);
+		if (position < 0)
+			return -EIO;
+	}
+	switch (cmd) {
+	case MTIOCTOP:
+		if (copy_from_user(&mtop, argp, sizeof(struct mtop)))
+			return -EFAULT;
+		return idetape_mtioctop(drive, mtop.mt_op, mtop.mt_count);
+	case MTIOCGET:
+		memset(&mtget, 0, sizeof(struct mtget));
+		mtget.mt_type = MT_ISSCSI2;
+		mtget.mt_blkno = position / tape->user_bs_factor - block_offset;
+		mtget.mt_dsreg =
+			((tape->blk_size * tape->user_bs_factor)
+			 << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK;
+
+		if (tape->drv_write_prot)
+			mtget.mt_gstat |= GMT_WR_PROT(0xffffffff);
+
+		return put_user_mtget(argp, &mtget);
+	case MTIOCPOS:
+		mtpos.mt_blkno = position / tape->user_bs_factor - block_offset;
+		return put_user_mtpos(argp, &mtpos);
+	default:
+		if (tape->chrdev_dir == IDETAPE_DIR_READ)
+			ide_tape_discard_merge_buffer(drive, 1);
+		return idetape_blkdev_ioctl(drive, cmd, arg);
+	}
+}
+
+static long idetape_chrdev_ioctl(struct file *file,
+				unsigned int cmd, unsigned long arg)
+{
+	long ret;
+	mutex_lock(&ide_tape_mutex);
+	ret = do_idetape_chrdev_ioctl(file, cmd, arg);
+	mutex_unlock(&ide_tape_mutex);
+	return ret;
+}
+
+static long idetape_chrdev_compat_ioctl(struct file *file,
+				unsigned int cmd, unsigned long arg)
+{
+	long ret;
+
+	if (cmd == MTIOCPOS32)
+		cmd = MTIOCPOS;
+	else if (cmd == MTIOCGET32)
+		cmd = MTIOCGET;
+
+	mutex_lock(&ide_tape_mutex);
+	ret = do_idetape_chrdev_ioctl(file, cmd, arg);
+	mutex_unlock(&ide_tape_mutex);
+	return ret;
+}
+
+/*
+ * Do a mode sense page 0 with block descriptor and if it succeeds set the tape
+ * block size with the reported value.
+ */
+static void ide_tape_get_bsize_from_bdesc(ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct ide_atapi_pc pc;
+	u8 buf[12];
+
+	idetape_create_mode_sense_cmd(&pc, IDETAPE_BLOCK_DESCRIPTOR);
+	if (ide_queue_pc_tail(drive, tape->disk, &pc, buf, pc.req_xfer)) {
+		printk(KERN_ERR "ide-tape: Can't get block descriptor\n");
+		if (tape->blk_size == 0) {
+			printk(KERN_WARNING "ide-tape: Cannot deal with zero "
+					    "block size, assuming 32k\n");
+			tape->blk_size = 32768;
+		}
+		return;
+	}
+	tape->blk_size = (buf[4 + 5] << 16) +
+				(buf[4 + 6] << 8)  +
+				 buf[4 + 7];
+	tape->drv_write_prot = (buf[2] & 0x80) >> 7;
+
+	ide_debug_log(IDE_DBG_FUNC, "blk_size: %d, write_prot: %d",
+		      tape->blk_size, tape->drv_write_prot);
+}
+
+static int idetape_chrdev_open(struct inode *inode, struct file *filp)
+{
+	unsigned int minor = iminor(inode), i = minor & ~0xc0;
+	ide_drive_t *drive;
+	idetape_tape_t *tape;
+	int retval;
+
+	if (i >= MAX_HWIFS * MAX_DRIVES)
+		return -ENXIO;
+
+	mutex_lock(&idetape_chrdev_mutex);
+
+	tape = ide_tape_get(NULL, true, i);
+	if (!tape) {
+		mutex_unlock(&idetape_chrdev_mutex);
+		return -ENXIO;
+	}
+
+	drive = tape->drive;
+	filp->private_data = tape;
+
+	ide_debug_log(IDE_DBG_FUNC, "enter");
+
+	/*
+	 * We really want to do nonseekable_open(inode, filp); here, but some
+	 * versions of tar incorrectly call lseek on tapes and bail out if that
+	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
+	 */
+	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
+
+
+	if (test_and_set_bit(ilog2(IDE_AFLAG_BUSY), &drive->atapi_flags)) {
+		retval = -EBUSY;
+		goto out_put_tape;
+	}
+
+	retval = idetape_wait_ready(drive, 60 * HZ);
+	if (retval) {
+		clear_bit(ilog2(IDE_AFLAG_BUSY), &drive->atapi_flags);
+		printk(KERN_ERR "ide-tape: %s: drive not ready\n", tape->name);
+		goto out_put_tape;
+	}
+
+	ide_tape_read_position(drive);
+	if (!test_bit(ilog2(IDE_AFLAG_ADDRESS_VALID), &drive->atapi_flags))
+		(void)idetape_rewind_tape(drive);
+
+	/* Read block size and write protect status from drive. */
+	ide_tape_get_bsize_from_bdesc(drive);
+
+	/* Set write protect flag if device is opened as read-only. */
+	if ((filp->f_flags & O_ACCMODE) == O_RDONLY)
+		tape->write_prot = 1;
+	else
+		tape->write_prot = tape->drv_write_prot;
+
+	/* Make sure drive isn't write protected if user wants to write. */
+	if (tape->write_prot) {
+		if ((filp->f_flags & O_ACCMODE) == O_WRONLY ||
+		    (filp->f_flags & O_ACCMODE) == O_RDWR) {
+			clear_bit(ilog2(IDE_AFLAG_BUSY), &drive->atapi_flags);
+			retval = -EROFS;
+			goto out_put_tape;
+		}
+	}
+
+	/* Lock the tape drive door so user can't eject. */
+	if (tape->chrdev_dir == IDETAPE_DIR_NONE) {
+		if (!ide_set_media_lock(drive, tape->disk, 1)) {
+			if (tape->door_locked != DOOR_EXPLICITLY_LOCKED)
+				tape->door_locked = DOOR_LOCKED;
+		}
+	}
+	mutex_unlock(&idetape_chrdev_mutex);
+
+	return 0;
+
+out_put_tape:
+	ide_tape_put(tape);
+
+	mutex_unlock(&idetape_chrdev_mutex);
+
+	return retval;
+}
+
+static void idetape_write_release(ide_drive_t *drive, unsigned int minor)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+	ide_tape_flush_merge_buffer(drive);
+	tape->buf = kmalloc(tape->buffer_size, GFP_KERNEL);
+	if (tape->buf != NULL) {
+		idetape_pad_zeros(drive, tape->blk_size *
+				(tape->user_bs_factor - 1));
+		kfree(tape->buf);
+		tape->buf = NULL;
+	}
+	idetape_write_filemark(drive);
+	idetape_flush_tape_buffers(drive);
+	idetape_flush_tape_buffers(drive);
+}
+
+static int idetape_chrdev_release(struct inode *inode, struct file *filp)
+{
+	struct ide_tape_obj *tape = filp->private_data;
+	ide_drive_t *drive = tape->drive;
+	unsigned int minor = iminor(inode);
+
+	mutex_lock(&idetape_chrdev_mutex);
+
+	tape = drive->driver_data;
+
+	ide_debug_log(IDE_DBG_FUNC, "enter");
+
+	if (tape->chrdev_dir == IDETAPE_DIR_WRITE)
+		idetape_write_release(drive, minor);
+	if (tape->chrdev_dir == IDETAPE_DIR_READ) {
+		if (minor < 128)
+			ide_tape_discard_merge_buffer(drive, 1);
+	}
+
+	if (minor < 128 && test_bit(ilog2(IDE_AFLAG_MEDIUM_PRESENT),
+				    &drive->atapi_flags))
+		(void) idetape_rewind_tape(drive);
+
+	if (tape->chrdev_dir == IDETAPE_DIR_NONE) {
+		if (tape->door_locked == DOOR_LOCKED) {
+			if (!ide_set_media_lock(drive, tape->disk, 0))
+				tape->door_locked = DOOR_UNLOCKED;
+		}
+	}
+	clear_bit(ilog2(IDE_AFLAG_BUSY), &drive->atapi_flags);
+	ide_tape_put(tape);
+
+	mutex_unlock(&idetape_chrdev_mutex);
+
+	return 0;
+}
+
+static void idetape_get_inquiry_results(ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct ide_atapi_pc pc;
+	u8 pc_buf[256];
+	char fw_rev[4], vendor_id[8], product_id[16];
+
+	idetape_create_inquiry_cmd(&pc);
+	if (ide_queue_pc_tail(drive, tape->disk, &pc, pc_buf, pc.req_xfer)) {
+		printk(KERN_ERR "ide-tape: %s: can't get INQUIRY results\n",
+				tape->name);
+		return;
+	}
+	memcpy(vendor_id, &pc_buf[8], 8);
+	memcpy(product_id, &pc_buf[16], 16);
+	memcpy(fw_rev, &pc_buf[32], 4);
+
+	ide_fixstring(vendor_id, 8, 0);
+	ide_fixstring(product_id, 16, 0);
+	ide_fixstring(fw_rev, 4, 0);
+
+	printk(KERN_INFO "ide-tape: %s <-> %s: %.8s %.16s rev %.4s\n",
+			drive->name, tape->name, vendor_id, product_id, fw_rev);
+}
+
+/*
+ * Ask the tape about its various parameters. In particular, we will adjust our
+ * data transfer buffer	size to the recommended value as returned by the tape.
+ */
+static void idetape_get_mode_sense_results(ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct ide_atapi_pc pc;
+	u8 buf[24], *caps;
+	u8 speed, max_speed;
+
+	idetape_create_mode_sense_cmd(&pc, IDETAPE_CAPABILITIES_PAGE);
+	if (ide_queue_pc_tail(drive, tape->disk, &pc, buf, pc.req_xfer)) {
+		printk(KERN_ERR "ide-tape: Can't get tape parameters - assuming"
+				" some default values\n");
+		tape->blk_size = 512;
+		put_unaligned(52,   (u16 *)&tape->caps[12]);
+		put_unaligned(540,  (u16 *)&tape->caps[14]);
+		put_unaligned(6*52, (u16 *)&tape->caps[16]);
+		return;
+	}
+	caps = buf + 4 + buf[3];
+
+	/* convert to host order and save for later use */
+	speed = be16_to_cpup((__be16 *)&caps[14]);
+	max_speed = be16_to_cpup((__be16 *)&caps[8]);
+
+	*(u16 *)&caps[8] = max_speed;
+	*(u16 *)&caps[12] = be16_to_cpup((__be16 *)&caps[12]);
+	*(u16 *)&caps[14] = speed;
+	*(u16 *)&caps[16] = be16_to_cpup((__be16 *)&caps[16]);
+
+	if (!speed) {
+		printk(KERN_INFO "ide-tape: %s: invalid tape speed "
+				"(assuming 650KB/sec)\n", drive->name);
+		*(u16 *)&caps[14] = 650;
+	}
+	if (!max_speed) {
+		printk(KERN_INFO "ide-tape: %s: invalid max_speed "
+				"(assuming 650KB/sec)\n", drive->name);
+		*(u16 *)&caps[8] = 650;
+	}
+
+	memcpy(&tape->caps, caps, 20);
+
+	/* device lacks locking support according to capabilities page */
+	if ((caps[6] & 1) == 0)
+		drive->dev_flags &= ~IDE_DFLAG_DOORLOCKING;
+
+	if (caps[7] & 0x02)
+		tape->blk_size = 512;
+	else if (caps[7] & 0x04)
+		tape->blk_size = 1024;
+}
+
+#ifdef CONFIG_IDE_PROC_FS
+#define ide_tape_devset_get(name, field) \
+static int get_##name(ide_drive_t *drive) \
+{ \
+	idetape_tape_t *tape = drive->driver_data; \
+	return tape->field; \
+}
+
+#define ide_tape_devset_set(name, field) \
+static int set_##name(ide_drive_t *drive, int arg) \
+{ \
+	idetape_tape_t *tape = drive->driver_data; \
+	tape->field = arg; \
+	return 0; \
+}
+
+#define ide_tape_devset_rw_field(_name, _field) \
+ide_tape_devset_get(_name, _field) \
+ide_tape_devset_set(_name, _field) \
+IDE_DEVSET(_name, DS_SYNC, get_##_name, set_##_name)
+
+#define ide_tape_devset_r_field(_name, _field) \
+ide_tape_devset_get(_name, _field) \
+IDE_DEVSET(_name, 0, get_##_name, NULL)
+
+static int mulf_tdsc(ide_drive_t *drive)	{ return 1000; }
+static int divf_tdsc(ide_drive_t *drive)	{ return   HZ; }
+static int divf_buffer(ide_drive_t *drive)	{ return    2; }
+static int divf_buffer_size(ide_drive_t *drive)	{ return 1024; }
+
+ide_devset_rw_flag(dsc_overlap, IDE_DFLAG_DSC_OVERLAP);
+
+ide_tape_devset_rw_field(tdsc, best_dsc_rw_freq);
+
+ide_tape_devset_r_field(avg_speed, avg_speed);
+ide_tape_devset_r_field(speed, caps[14]);
+ide_tape_devset_r_field(buffer, caps[16]);
+ide_tape_devset_r_field(buffer_size, buffer_size);
+
+static const struct ide_proc_devset idetape_settings[] = {
+	__IDE_PROC_DEVSET(avg_speed,	0, 0xffff, NULL, NULL),
+	__IDE_PROC_DEVSET(buffer,	0, 0xffff, NULL, divf_buffer),
+	__IDE_PROC_DEVSET(buffer_size,	0, 0xffff, NULL, divf_buffer_size),
+	__IDE_PROC_DEVSET(dsc_overlap,	0,      1, NULL, NULL),
+	__IDE_PROC_DEVSET(speed,	0, 0xffff, NULL, NULL),
+	__IDE_PROC_DEVSET(tdsc,		IDETAPE_DSC_RW_MIN, IDETAPE_DSC_RW_MAX,
+					mulf_tdsc, divf_tdsc),
+	{ NULL },
+};
+#endif
+
+/*
+ * The function below is called to:
+ *
+ * 1. Initialize our various state variables.
+ * 2. Ask the tape for its capabilities.
+ * 3. Allocate a buffer which will be used for data transfer. The buffer size
+ * is chosen based on the recommendation which we received in step 2.
+ *
+ * Note that at this point ide.c already assigned us an irq, so that we can
+ * queue requests here and wait for their completion.
+ */
+static void idetape_setup(ide_drive_t *drive, idetape_tape_t *tape, int minor)
+{
+	unsigned long t;
+	int speed;
+	u16 *ctl = (u16 *)&tape->caps[12];
+
+	ide_debug_log(IDE_DBG_FUNC, "minor: %d", minor);
+
+	drive->pc_callback = ide_tape_callback;
+
+	drive->dev_flags |= IDE_DFLAG_DSC_OVERLAP;
+
+	if (drive->hwif->host_flags & IDE_HFLAG_NO_DSC) {
+		printk(KERN_INFO "ide-tape: %s: disabling DSC overlap\n",
+				 tape->name);
+		drive->dev_flags &= ~IDE_DFLAG_DSC_OVERLAP;
+	}
+
+	/* Seagate Travan drives do not support DSC overlap. */
+	if (strstr((char *)&drive->id[ATA_ID_PROD], "Seagate STT3401"))
+		drive->dev_flags &= ~IDE_DFLAG_DSC_OVERLAP;
+
+	tape->minor = minor;
+	tape->name[0] = 'h';
+	tape->name[1] = 't';
+	tape->name[2] = '0' + minor;
+	tape->chrdev_dir = IDETAPE_DIR_NONE;
+
+	idetape_get_inquiry_results(drive);
+	idetape_get_mode_sense_results(drive);
+	ide_tape_get_bsize_from_bdesc(drive);
+	tape->user_bs_factor = 1;
+	tape->buffer_size = *ctl * tape->blk_size;
+	while (tape->buffer_size > 0xffff) {
+		printk(KERN_NOTICE "ide-tape: decreasing stage size\n");
+		*ctl /= 2;
+		tape->buffer_size = *ctl * tape->blk_size;
+	}
+
+	/* select the "best" DSC read/write polling freq */
+	speed = max(*(u16 *)&tape->caps[14], *(u16 *)&tape->caps[8]);
+
+	t = (IDETAPE_FIFO_THRESHOLD * tape->buffer_size * HZ) / (speed * 1000);
+
+	/*
+	 * Ensure that the number we got makes sense; limit it within
+	 * IDETAPE_DSC_RW_MIN and IDETAPE_DSC_RW_MAX.
+	 */
+	tape->best_dsc_rw_freq = clamp_t(unsigned long, t, IDETAPE_DSC_RW_MIN,
+					 IDETAPE_DSC_RW_MAX);
+	printk(KERN_INFO "ide-tape: %s <-> %s: %dKBps, %d*%dkB buffer, "
+		"%ums tDSC%s\n",
+		drive->name, tape->name, *(u16 *)&tape->caps[14],
+		(*(u16 *)&tape->caps[16] * 512) / tape->buffer_size,
+		tape->buffer_size / 1024,
+		jiffies_to_msecs(tape->best_dsc_rw_freq),
+		(drive->dev_flags & IDE_DFLAG_USING_DMA) ? ", DMA" : "");
+
+	ide_proc_register_driver(drive, tape->driver);
+}
+
+static void ide_tape_remove(ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+	ide_proc_unregister_driver(drive, tape->driver);
+	device_del(&tape->dev);
+	ide_unregister_region(tape->disk);
+
+	mutex_lock(&idetape_ref_mutex);
+	put_device(&tape->dev);
+	mutex_unlock(&idetape_ref_mutex);
+}
+
+static void ide_tape_release(struct device *dev)
+{
+	struct ide_tape_obj *tape = to_ide_drv(dev, ide_tape_obj);
+	ide_drive_t *drive = tape->drive;
+	struct gendisk *g = tape->disk;
+
+	BUG_ON(tape->valid);
+
+	drive->dev_flags &= ~IDE_DFLAG_DSC_OVERLAP;
+	drive->driver_data = NULL;
+	device_destroy(idetape_sysfs_class, MKDEV(IDETAPE_MAJOR, tape->minor));
+	device_destroy(idetape_sysfs_class,
+			MKDEV(IDETAPE_MAJOR, tape->minor + 128));
+	idetape_devs[tape->minor] = NULL;
+	g->private_data = NULL;
+	put_disk(g);
+	kfree(tape);
+}
+
+#ifdef CONFIG_IDE_PROC_FS
+static int idetape_name_proc_show(struct seq_file *m, void *v)
+{
+	ide_drive_t	*drive = (ide_drive_t *) m->private;
+	idetape_tape_t	*tape = drive->driver_data;
+
+	seq_printf(m, "%s\n", tape->name);
+	return 0;
+}
+
+static ide_proc_entry_t idetape_proc[] = {
+	{ "capacity",	S_IFREG|S_IRUGO,	ide_capacity_proc_show	},
+	{ "name",	S_IFREG|S_IRUGO,	idetape_name_proc_show	},
+	{}
+};
+
+static ide_proc_entry_t *ide_tape_proc_entries(ide_drive_t *drive)
+{
+	return idetape_proc;
+}
+
+static const struct ide_proc_devset *ide_tape_proc_devsets(ide_drive_t *drive)
+{
+	return idetape_settings;
+}
+#endif
+
+static int ide_tape_probe(ide_drive_t *);
+
+static struct ide_driver idetape_driver = {
+	.gen_driver = {
+		.owner		= THIS_MODULE,
+		.name		= "ide-tape",
+		.bus		= &ide_bus_type,
+	},
+	.probe			= ide_tape_probe,
+	.remove			= ide_tape_remove,
+	.version		= IDETAPE_VERSION,
+	.do_request		= idetape_do_request,
+#ifdef CONFIG_IDE_PROC_FS
+	.proc_entries		= ide_tape_proc_entries,
+	.proc_devsets		= ide_tape_proc_devsets,
+#endif
+};
+
+/* Our character device supporting functions, passed to register_chrdev. */
+static const struct file_operations idetape_fops = {
+	.owner		= THIS_MODULE,
+	.read		= idetape_chrdev_read,
+	.write		= idetape_chrdev_write,
+	.unlocked_ioctl	= idetape_chrdev_ioctl,
+	.compat_ioctl	= IS_ENABLED(CONFIG_COMPAT) ?
+			  idetape_chrdev_compat_ioctl : NULL,
+	.open		= idetape_chrdev_open,
+	.release	= idetape_chrdev_release,
+	.llseek		= noop_llseek,
+};
+
+static int idetape_open(struct block_device *bdev, fmode_t mode)
+{
+	struct ide_tape_obj *tape;
+
+	mutex_lock(&ide_tape_mutex);
+	tape = ide_tape_get(bdev->bd_disk, false, 0);
+	mutex_unlock(&ide_tape_mutex);
+
+	if (!tape)
+		return -ENXIO;
+
+	return 0;
+}
+
+static void idetape_release(struct gendisk *disk, fmode_t mode)
+{
+	struct ide_tape_obj *tape = ide_drv_g(disk, ide_tape_obj);
+
+	mutex_lock(&ide_tape_mutex);
+	ide_tape_put(tape);
+	mutex_unlock(&ide_tape_mutex);
+}
+
+static int idetape_ioctl(struct block_device *bdev, fmode_t mode,
+			unsigned int cmd, unsigned long arg)
+{
+	struct ide_tape_obj *tape = ide_drv_g(bdev->bd_disk, ide_tape_obj);
+	ide_drive_t *drive = tape->drive;
+	int err;
+
+	mutex_lock(&ide_tape_mutex);
+	err = generic_ide_ioctl(drive, bdev, cmd, arg);
+	if (err == -EINVAL)
+		err = idetape_blkdev_ioctl(drive, cmd, arg);
+	mutex_unlock(&ide_tape_mutex);
+
+	return err;
+}
+
+static int idetape_compat_ioctl(struct block_device *bdev, fmode_t mode,
+				unsigned int cmd, unsigned long arg)
+{
+        if (cmd == 0x0340 || cmd == 0x350)
+		arg = (unsigned long)compat_ptr(arg);
+
+	return idetape_ioctl(bdev, mode, cmd, arg);
+}
+
+static const struct block_device_operations idetape_block_ops = {
+	.owner		= THIS_MODULE,
+	.open		= idetape_open,
+	.release	= idetape_release,
+	.ioctl		= idetape_ioctl,
+	.compat_ioctl	= IS_ENABLED(CONFIG_COMPAT) ?
+				idetape_compat_ioctl : NULL,
+};
+
+static int ide_tape_probe(ide_drive_t *drive)
+{
+	idetape_tape_t *tape;
+	struct gendisk *g;
+	int minor;
+
+	ide_debug_log(IDE_DBG_FUNC, "enter");
+
+	if (!strstr(DRV_NAME, drive->driver_req))
+		goto failed;
+
+	if (drive->media != ide_tape)
+		goto failed;
+
+	if ((drive->dev_flags & IDE_DFLAG_ID_READ) &&
+	    ide_check_atapi_device(drive, DRV_NAME) == 0) {
+		printk(KERN_ERR "ide-tape: %s: not supported by this version of"
+				" the driver\n", drive->name);
+		goto failed;
+	}
+	tape = kzalloc(sizeof(idetape_tape_t), GFP_KERNEL);
+	if (tape == NULL) {
+		printk(KERN_ERR "ide-tape: %s: Can't allocate a tape struct\n",
+				drive->name);
+		goto failed;
+	}
+
+	g = alloc_disk(1 << PARTN_BITS);
+	if (!g)
+		goto out_free_tape;
+
+	ide_init_disk(g, drive);
+
+	tape->dev.parent = &drive->gendev;
+	tape->dev.release = ide_tape_release;
+	dev_set_name(&tape->dev, "%s", dev_name(&drive->gendev));
+
+	if (device_register(&tape->dev))
+		goto out_free_disk;
+
+	tape->drive = drive;
+	tape->driver = &idetape_driver;
+	tape->disk = g;
+
+	g->private_data = &tape->driver;
+
+	drive->driver_data = tape;
+
+	mutex_lock(&idetape_ref_mutex);
+	for (minor = 0; idetape_devs[minor]; minor++)
+		;
+	idetape_devs[minor] = tape;
+	mutex_unlock(&idetape_ref_mutex);
+
+	idetape_setup(drive, tape, minor);
+
+	device_create(idetape_sysfs_class, &drive->gendev,
+		      MKDEV(IDETAPE_MAJOR, minor), NULL, "%s", tape->name);
+	device_create(idetape_sysfs_class, &drive->gendev,
+		      MKDEV(IDETAPE_MAJOR, minor + 128), NULL,
+		      "n%s", tape->name);
+
+	g->fops = &idetape_block_ops;
+	ide_register_region(g);
+
+	return 0;
+
+out_free_disk:
+	put_disk(g);
+out_free_tape:
+	kfree(tape);
+failed:
+	return -ENODEV;
+}
+
+static void __exit idetape_exit(void)
+{
+	driver_unregister(&idetape_driver.gen_driver);
+	class_destroy(idetape_sysfs_class);
+	unregister_chrdev(IDETAPE_MAJOR, "ht");
+}
+
+static int __init idetape_init(void)
+{
+	int error = 1;
+	idetape_sysfs_class = class_create(THIS_MODULE, "ide_tape");
+	if (IS_ERR(idetape_sysfs_class)) {
+		idetape_sysfs_class = NULL;
+		printk(KERN_ERR "Unable to create sysfs class for ide tapes\n");
+		error = -EBUSY;
+		goto out;
+	}
+
+	if (register_chrdev(IDETAPE_MAJOR, "ht", &idetape_fops)) {
+		printk(KERN_ERR "ide-tape: Failed to register chrdev"
+				" interface\n");
+		error = -EBUSY;
+		goto out_free_class;
+	}
+
+	error = driver_register(&idetape_driver.gen_driver);
+	if (error)
+		goto out_free_chrdev;
+
+	return 0;
+
+out_free_chrdev:
+	unregister_chrdev(IDETAPE_MAJOR, "ht");
+out_free_class:
+	class_destroy(idetape_sysfs_class);
+out:
+	return error;
+}
+
+MODULE_ALIAS("ide:*m-tape*");
+module_init(idetape_init);
+module_exit(idetape_exit);
+MODULE_ALIAS_CHARDEV_MAJOR(IDETAPE_MAJOR);
+MODULE_DESCRIPTION("ATAPI Streaming TAPE Driver");
+MODULE_LICENSE("GPL");