ide-tape.c 162.5 KB
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/*
 * linux/drivers/ide/ide-tape.c		Version 1.19	Nov, 2003
 *
 * Copyright (C) 1995 - 1999 Gadi Oxman <gadio@netvision.net.il>
 *
 * $Header$
 *
 * 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).
 */
 
/*
 * IDE ATAPI streaming tape driver.
 *
 * This driver is a part of the Linux ide driver and works in co-operation
 * with linux/drivers/block/ide.c.
 *
 * The driver, in co-operation with ide.c, basically traverses the 
 * request-list for the block device interface. The character device
 * interface, on the other hand, creates new requests, adds them
 * to the request-list of the block device, and waits for their completion.
 *
 * Pipelined operation mode is now supported on both reads and writes.
 *
 * The block device major and minor numbers are determined from the
 * tape's relative position in the ide interfaces, as explained in ide.c.
 *
 * The character device interface consists of the following devices:
 *
 * ht0		major 37, minor 0	first  IDE tape, rewind on close.
 * ht1		major 37, minor 1	second IDE tape, rewind on close.
 * ...
 * nht0		major 37, minor 128	first  IDE tape, no rewind on close.
 * nht1		major 37, minor 129	second IDE tape, no rewind on close.
 * ...
 *
 * Run linux/scripts/MAKEDEV.ide to create the above entries.
 *
 * The general magnetic tape commands compatible interface, as defined by
 * include/linux/mtio.h, is accessible through the character device.
 *
 * General ide driver configuration options, such as the interrupt-unmask
 * flag, can be configured by issuing an ioctl to the block device interface,
 * as any other ide device.
 *
 * Our own ide-tape ioctl's can be issued to either the block device or
 * the character device interface.
 *
 * Maximal throughput with minimal bus load will usually be achieved in the
 * following scenario:
 *
 *	1.	ide-tape is operating in the pipelined operation mode.
 *	2.	No buffering is performed by the user backup program.
 *
 * Testing was done with a 2 GB CONNER CTMA 4000 IDE ATAPI Streaming Tape Drive.
 * 
 * Ver 0.1   Nov  1 95   Pre-working code :-)
 * Ver 0.2   Nov 23 95   A short backup (few megabytes) and restore procedure
 *                        was successful ! (Using tar cvf ... on the block
 *                        device interface).
 *                       A longer backup resulted in major swapping, bad
 *                        overall Linux performance and eventually failed as
 *                        we received non serial read-ahead requests from the
 *                        buffer cache.
 * Ver 0.3   Nov 28 95   Long backups are now possible, thanks to the
 *                        character device interface. Linux's responsiveness
 *                        and performance doesn't seem to be much affected
 *                        from the background backup procedure.
 *                       Some general mtio.h magnetic tape operations are
 *                        now supported by our character device. As a result,
 *                        popular tape utilities are starting to work with
 *                        ide tapes :-)
 *                       The following configurations were tested:
 *                       	1. An IDE ATAPI TAPE shares the same interface
 *                       	   and irq with an IDE ATAPI CDROM.
 *                        	2. An IDE ATAPI TAPE shares the same interface
 *                          	   and irq with a normal IDE disk.
 *                        Both configurations seemed to work just fine !
 *                        However, to be on the safe side, it is meanwhile
 *                        recommended to give the IDE TAPE its own interface
 *                        and irq.
 *                       The one thing which needs to be done here is to
 *                        add a "request postpone" feature to ide.c,
 *                        so that we won't have to wait for the tape to finish
 *                        performing a long media access (DSC) request (such
 *                        as a rewind) before we can access the other device
 *                        on the same interface. This effect doesn't disturb
 *                        normal operation most of the time because read/write
 *                        requests are relatively fast, and once we are
 *                        performing one tape r/w request, a lot of requests
 *                        from the other device can be queued and ide.c will
 *			  service all of them after this single tape request.
 * Ver 1.0   Dec 11 95   Integrated into Linux 1.3.46 development tree.
 *                       On each read / write request, we now ask the drive
 *                        if we can transfer a constant number of bytes
 *                        (a parameter of the drive) only to its buffers,
 *                        without causing actual media access. If we can't,
 *                        we just wait until we can by polling the DSC bit.
 *                        This ensures that while we are not transferring
 *                        more bytes than the constant referred to above, the
 *                        interrupt latency will not become too high and
 *                        we won't cause an interrupt timeout, as happened
 *                        occasionally in the previous version.
 *                       While polling for DSC, the current request is
 *                        postponed and ide.c is free to handle requests from
 *                        the other device. This is handled transparently to
 *                        ide.c. The hwgroup locking method which was used
 *                        in the previous version was removed.
 *                       Use of new general features which are provided by
 *                        ide.c for use with atapi devices.
 *                        (Programming done by Mark Lord)
 *                       Few potential bug fixes (Again, suggested by Mark)
 *                       Single character device data transfers are now
 *                        not limited in size, as they were before.
 *                       We are asking the tape about its recommended
 *                        transfer unit and send a larger data transfer
 *                        as several transfers of the above size.
 *                        For best results, use an integral number of this
 *                        basic unit (which is shown during driver
 *                        initialization). I will soon add an ioctl to get
 *                        this important parameter.
 *                       Our data transfer buffer is allocated on startup,
 *                        rather than before each data transfer. This should
 *                        ensure that we will indeed have a data buffer.
 * Ver 1.1   Dec 14 95   Fixed random problems which occurred when the tape
 *                        shared an interface with another device.
 *                        (poll_for_dsc was a complete mess).
 *                       Removed some old (non-active) code which had
 *                        to do with supporting buffer cache originated
 *                        requests.
 *                       The block device interface can now be opened, so
 *                        that general ide driver features like the unmask
 *                        interrupts flag can be selected with an ioctl.
 *                        This is the only use of the block device interface.
 *                       New fast pipelined operation mode (currently only on
 *                        writes). When using the pipelined mode, the
 *                        throughput can potentially reach the maximum
 *                        tape supported throughput, regardless of the
 *                        user backup program. On my tape drive, it sometimes
 *                        boosted performance by a factor of 2. Pipelined
 *                        mode is enabled by default, but since it has a few
 *                        downfalls as well, you may want to disable it.
 *                        A short explanation of the pipelined operation mode
 *                        is available below.
 * Ver 1.2   Jan  1 96   Eliminated pipelined mode race condition.
 *                       Added pipeline read mode. As a result, restores
 *                        are now as fast as backups.
 *                       Optimized shared interface behavior. The new behavior
 *                        typically results in better IDE bus efficiency and
 *                        higher tape throughput.
 *                       Pre-calculation of the expected read/write request
 *                        service time, based on the tape's parameters. In
 *                        the pipelined operation mode, this allows us to
 *                        adjust our polling frequency to a much lower value,
 *                        and thus to dramatically reduce our load on Linux,
 *                        without any decrease in performance.
 *                       Implemented additional mtio.h operations.
 *                       The recommended user block size is returned by
 *                        the MTIOCGET ioctl.
 *                       Additional minor changes.
 * Ver 1.3   Feb  9 96   Fixed pipelined read mode bug which prevented the
 *                        use of some block sizes during a restore procedure.
 *                       The character device interface will now present a
 *                        continuous view of the media - any mix of block sizes
 *                        during a backup/restore procedure is supported. The
 *                        driver will buffer the requests internally and
 *                        convert them to the tape's recommended transfer
 *                        unit, making performance almost independent of the
 *                        chosen user block size.
 *                       Some improvements in error recovery.
 *                       By cooperating with ide-dma.c, bus mastering DMA can
 *                        now sometimes be used with IDE tape drives as well.
 *                        Bus mastering DMA has the potential to dramatically
 *                        reduce the CPU's overhead when accessing the device,
 *                        and can be enabled by using hdparm -d1 on the tape's
 *                        block device interface. For more info, read the
 *                        comments in ide-dma.c.
 * Ver 1.4   Mar 13 96   Fixed serialize support.
 * Ver 1.5   Apr 12 96   Fixed shared interface operation, broken in 1.3.85.
 *                       Fixed pipelined read mode inefficiency.
 *                       Fixed nasty null dereferencing bug.
 * Ver 1.6   Aug 16 96   Fixed FPU usage in the driver.
 *                       Fixed end of media bug.
 * Ver 1.7   Sep 10 96   Minor changes for the CONNER CTT8000-A model.
 * Ver 1.8   Sep 26 96   Attempt to find a better balance between good
 *                        interactive response and high system throughput.
 * Ver 1.9   Nov  5 96   Automatically cross encountered filemarks rather
 *                        than requiring an explicit FSF command.
 *                       Abort pending requests at end of media.
 *                       MTTELL was sometimes returning incorrect results.
 *                       Return the real block size in the MTIOCGET ioctl.
 *                       Some error recovery bug fixes.
 * Ver 1.10  Nov  5 96   Major reorganization.
 *                       Reduced CPU overhead a bit by eliminating internal
 *                        bounce buffers.
 *                       Added module support.
 *                       Added multiple tape drives support.
 *                       Added partition support.
 *                       Rewrote DSC handling.
 *                       Some portability fixes.
 *                       Removed ide-tape.h.
 *                       Additional minor changes.
 * Ver 1.11  Dec  2 96   Bug fix in previous DSC timeout handling.
 *                       Use ide_stall_queue() for DSC overlap.
 *                       Use the maximum speed rather than the current speed
 *                        to compute the request service time.
 * Ver 1.12  Dec  7 97   Fix random memory overwriting and/or last block data
 *                        corruption, which could occur if the total number
 *                        of bytes written to the tape was not an integral
 *                        number of tape blocks.
 *                       Add support for INTERRUPT DRQ devices.
 * Ver 1.13  Jan  2 98   Add "speed == 0" work-around for HP COLORADO 5GB
 * Ver 1.14  Dec 30 98   Partial fixes for the Sony/AIWA tape drives.
 *                       Replace cli()/sti() with hwgroup spinlocks.
 * Ver 1.15  Mar 25 99   Fix SMP race condition by replacing hwgroup
 *                        spinlock with private per-tape spinlock.
 * Ver 1.16  Sep  1 99   Add OnStream tape support.
 *                       Abort read pipeline on EOD.
 *                       Wait for the tape to become ready in case it returns
 *                        "in the process of becoming ready" on open().
 *                       Fix zero padding of the last written block in
 *                        case the tape block size is larger than PAGE_SIZE.
 *                       Decrease the default disconnection time to tn.
 * Ver 1.16e Oct  3 99   Minor fixes.
 * Ver 1.16e1 Oct 13 99  Patches by Arnold Niessen,
 *                          niessen@iae.nl / arnold.niessen@philips.com
 *                   GO-1)  Undefined code in idetape_read_position
 *				according to Gadi's email
 *                   AJN-1) Minor fix asc == 11 should be asc == 0x11
 *                               in idetape_issue_packet_command (did effect
 *                               debugging output only)
 *                   AJN-2) Added more debugging output, and
 *                              added ide-tape: where missing. I would also
 *				like to add tape->name where possible
 *                   AJN-3) Added different debug_level's 
 *                              via /proc/ide/hdc/settings
 * 				"debug_level" determines amount of debugging output;
 * 				can be changed using /proc/ide/hdx/settings
 * 				0 : almost no debugging output
 * 				1 : 0+output errors only
 * 				2 : 1+output all sensekey/asc
 * 				3 : 2+follow all chrdev related procedures
 * 				4 : 3+follow all procedures
 * 				5 : 4+include pc_stack rq_stack info
 * 				6 : 5+USE_COUNT updates
 *                   AJN-4) Fixed timeout for retension in idetape_queue_pc_tail
 *				from 5 to 10 minutes
 *                   AJN-5) Changed maximum number of blocks to skip when
 *                              reading tapes with multiple consecutive write
 *                              errors from 100 to 1000 in idetape_get_logical_blk
 *                   Proposed changes to code:
 *                   1) output "logical_blk_num" via /proc
 *                   2) output "current_operation" via /proc
 *                   3) Either solve or document the fact that `mt rewind' is
 *                      required after reading from /dev/nhtx to be
 *			able to rmmod the idetape module;
 *			Also, sometimes an application finishes but the
 *			device remains `busy' for some time. Same cause ?
 *                   Proposed changes to release-notes:
 *		     4) write a simple `quickstart' section in the
 *                      release notes; I volunteer if you don't want to
 * 		     5) include a pointer to video4linux in the doc
 *                      to stimulate video applications
 *                   6) release notes lines 331 and 362: explain what happens
 *			if the application data rate is higher than 1100 KB/s; 
 *			similar approach to lower-than-500 kB/s ?
 *		     7) 6.6 Comparison; wouldn't it be better to allow different 
 *			strategies for read and write ?
 *			Wouldn't it be better to control the tape buffer
 *			contents instead of the bandwidth ?
 *		     8) line 536: replace will by would (if I understand
 *			this section correctly, a hypothetical and unwanted situation
 *			 is being described)
 * Ver 1.16f Dec 15 99   Change place of the secondary OnStream header frames.
 * Ver 1.17  Nov 2000 / Jan 2001  Marcel Mol, marcel@mesa.nl
 *			- Add idetape_onstream_mode_sense_tape_parameter_page
 *			  function to get tape capacity in frames: tape->capacity.
 *			- Add support for DI-50 drives( or any DI- drive).
 *			- 'workaround' for read error/blank block around block 3000.
 *			- Implement Early warning for end of media for Onstream.
 *			- Cosmetic code changes for readability.
 *			- Idetape_position_tape should not use SKIP bit during
 *			  Onstream read recovery.
 *			- Add capacity, logical_blk_num and first/last_frame_position
 *			  to /proc/ide/hd?/settings.
 *			- Module use count was gone in the Linux 2.4 driver.
 * Ver 1.17a Apr 2001 Willem Riede osst@riede.org
 * 			- Get drive's actual block size from mode sense block descriptor
 * 			- Limit size of pipeline
 * Ver 1.17b Oct 2002   Alan Stern <stern@rowland.harvard.edu>
 *			Changed IDETAPE_MIN_PIPELINE_STAGES to 1 and actually used
 *			 it in the code!
 *			Actually removed aborted stages in idetape_abort_pipeline
 *			 instead of just changing the command code.
 *			Made the transfer byte count for Request Sense equal to the
 *			 actual length of the data transfer.
 *			Changed handling of partial data transfers: they do not
 *			 cause DMA errors.
 *			Moved initiation of DMA transfers to the correct place.
 *			Removed reference to unallocated memory.
 *			Made __idetape_discard_read_pipeline return the number of
 *			 sectors skipped, not the number of stages.
 *			Replaced errant kfree() calls with __idetape_kfree_stage().
 *			Fixed off-by-one error in testing the pipeline length.
 *			Fixed handling of filemarks in the read pipeline.
 *			Small code optimization for MTBSF and MTBSFM ioctls.
 *			Don't try to unlock the door during device close if is
 *			 already unlocked!
 *			Cosmetic fixes to miscellaneous debugging output messages.
 *			Set the minimum /proc/ide/hd?/settings values for "pipeline",
 *			 "pipeline_min", and "pipeline_max" to 1.
 *
 * Here are some words from the first releases of hd.c, which are quoted
 * in ide.c and apply here as well:
 *
 * | Special care is recommended.  Have Fun!
 *
 */

/*
 * An overview of the pipelined operation mode.
 *
 * In the pipelined write mode, we will usually just add requests to our
 * pipeline and return immediately, before we even start to service them. The
 * user program will then have enough time to prepare the next request while
 * we are still busy servicing previous requests. In the pipelined read mode,
 * the situation is similar - we add read-ahead requests into the pipeline,
 * before the user even requested them.
 *
 * The pipeline can be viewed as a "safety net" which will be activated when
 * the system load is high and prevents the user backup program from keeping up
 * with the current tape speed. At this point, the pipeline will get
 * shorter and shorter but the tape will still be streaming at the same speed.
 * Assuming we have enough pipeline stages, the system load will hopefully
 * decrease before the pipeline is completely empty, and the backup program
 * will be able to "catch up" and refill the pipeline again.
 * 
 * When using the pipelined mode, it would be best to disable any type of
 * buffering done by the user program, as ide-tape already provides all the
 * benefits in the kernel, where it can be done in a more efficient way.
 * As we will usually not block the user program on a request, the most
 * efficient user code will then be a simple read-write-read-... cycle.
 * Any additional logic will usually just slow down the backup process.
 *
 * Using the pipelined mode, I get a constant over 400 KBps throughput,
 * which seems to be the maximum throughput supported by my tape.
 *
 * However, there are some downfalls:
 *
 *	1.	We use memory (for data buffers) in proportional to the number
 *		of pipeline stages (each stage is about 26 KB with my tape).
 *	2.	In the pipelined write mode, we cheat and postpone error codes
 *		to the user task. In read mode, the actual tape position
 *		will be a bit further than the last requested block.
 *
 * Concerning (1):
 *
 *	1.	We allocate stages dynamically only when we need them. When
 *		we don't need them, we don't consume additional memory. In
 *		case we can't allocate stages, we just manage without them
 *		(at the expense of decreased throughput) so when Linux is
 *		tight in memory, we will not pose additional difficulties.
 *
 *	2.	The maximum number of stages (which is, in fact, the maximum
 *		amount of memory) which we allocate is limited by the compile
 *		time parameter IDETAPE_MAX_PIPELINE_STAGES.
 *
 *	3.	The maximum number of stages is a controlled parameter - We
 *		don't start from the user defined maximum number of stages
 *		but from the lower IDETAPE_MIN_PIPELINE_STAGES (again, we
 *		will not even allocate this amount of stages if the user
 *		program can't handle the speed). We then implement a feedback
 *		loop which checks if the pipeline is empty, and if it is, we
 *		increase the maximum number of stages as necessary until we
 *		reach the optimum value which just manages to keep the tape
 *		busy with minimum allocated memory or until we reach
 *		IDETAPE_MAX_PIPELINE_STAGES.
 *
 * Concerning (2):
 *
 *	In pipelined write mode, ide-tape can not return accurate error codes
 *	to the user program since we usually just add the request to the
 *      pipeline without waiting for it to be serviced. In case an error
 *      occurs, I will report it on the next user request.
 *
 *	In the pipelined read mode, subsequent read requests or forward
 *	filemark spacing will perform correctly, as we preserve all blocks
 *	and filemarks which we encountered during our excess read-ahead.
 * 
 *	For accurate tape positioning and error reporting, disabling
 *	pipelined mode might be the best option.
 *
 * You can enable/disable/tune the pipelined operation mode by adjusting
 * the compile time parameters below.
 */

/*
 *	Possible improvements.
 *
 *	1.	Support for the ATAPI overlap protocol.
 *
 *		In order to maximize bus throughput, we currently use the DSC
 *		overlap method which enables ide.c to service requests from the
 *		other device while the tape is busy executing a command. The
 *		DSC overlap method involves polling the tape's status register
 *		for the DSC bit, and servicing the other device while the tape
 *		isn't ready.
 *
 *		In the current QIC development standard (December 1995),
 *		it is recommended that new tape drives will *in addition* 
 *		implement the ATAPI overlap protocol, which is used for the
 *		same purpose - efficient use of the IDE bus, but is interrupt
 *		driven and thus has much less CPU overhead.
 *
 *		ATAPI overlap is likely to be supported in most new ATAPI
 *		devices, including new ATAPI cdroms, and thus provides us
 *		a method by which we can achieve higher throughput when
 *		sharing a (fast) ATA-2 disk with any (slow) new ATAPI device.
 */

#define IDETAPE_VERSION "1.19"

#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>
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#include <linux/jiffies.h>
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#include <linux/major.h>
#include <linux/errno.h>
#include <linux/genhd.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/ide.h>
#include <linux/smp_lock.h>
#include <linux/completion.h>
#include <linux/bitops.h>
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#include <linux/mutex.h>
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#include <asm/byteorder.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/unaligned.h>

/*
 * partition
 */
typedef struct os_partition_s {
	__u8	partition_num;
	__u8	par_desc_ver;
	__u16	wrt_pass_cntr;
	__u32	first_frame_addr;
	__u32	last_frame_addr;
	__u32	eod_frame_addr;
} os_partition_t;

/*
 * DAT entry
 */
typedef struct os_dat_entry_s {
	__u32	blk_sz;
	__u16	blk_cnt;
	__u8	flags;
	__u8	reserved;
} os_dat_entry_t;

/*
 * DAT
 */
#define OS_DAT_FLAGS_DATA	(0xc)
#define OS_DAT_FLAGS_MARK	(0x1)

typedef struct os_dat_s {
	__u8		dat_sz;
	__u8		reserved1;
	__u8		entry_cnt;
	__u8		reserved3;
	os_dat_entry_t	dat_list[16];
} os_dat_t;

#include <linux/mtio.h>

/**************************** Tunable parameters *****************************/


/*
 *	Pipelined mode parameters.
 *
 *	We try to use the minimum number of stages which is enough to
 *	keep the tape constantly streaming. To accomplish that, we implement
 *	a feedback loop around the maximum number of stages:
 *
 *	We start from MIN maximum stages (we will not even use MIN stages
 *      if we don't need them), increment it by RATE*(MAX-MIN)
 *	whenever we sense that the pipeline is empty, until we reach
 *	the optimum value or until we reach MAX.
 *
 *	Setting the following parameter to 0 is illegal: the pipelined mode
 *	cannot be disabled (calculate_speeds() divides by tape->max_stages.)
 */
#define IDETAPE_MIN_PIPELINE_STAGES	  1
#define IDETAPE_MAX_PIPELINE_STAGES	400
#define IDETAPE_INCREASE_STAGES_RATE	 20

/*
 *	The following are used to debug the driver:
 *
 *	Setting IDETAPE_DEBUG_INFO to 1 will report device capabilities.
 *	Setting IDETAPE_DEBUG_LOG to 1 will log driver flow control.
 *	Setting IDETAPE_DEBUG_BUGS to 1 will enable self-sanity checks in
 *	some places.
 *
 *	Setting them to 0 will restore normal operation mode:
 *
 *		1.	Disable logging normal successful operations.
 *		2.	Disable self-sanity checks.
 *		3.	Errors will still be logged, of course.
 *
 *	All the #if DEBUG code will be removed some day, when the driver
 *	is verified to be stable enough. This will make it much more
 *	esthetic.
 */
#define IDETAPE_DEBUG_INFO		0
#define IDETAPE_DEBUG_LOG		0
#define IDETAPE_DEBUG_BUGS		1

/*
 *	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

/*
 *	With each packet command, we allocate a buffer of
 *	IDETAPE_PC_BUFFER_SIZE bytes. This is used for several packet
 *	commands (Not for READ/WRITE commands).
 */
#define IDETAPE_PC_BUFFER_SIZE		256

/*
 *	In various places in the driver, we need to allocate storage
 *	for packet commands and requests, which will remain valid while
 *	we leave the driver to wait for an interrupt or a timeout event.
 */
#define IDETAPE_PC_STACK		(10 + IDETAPE_MAX_PC_RETRIES)

/*
 * Some drives (for example, Seagate STT3401A Travan) require a very long
 * timeout, because they don't return an interrupt or clear their busy bit
 * until after the command completes (even retension commands).
 */
#define IDETAPE_WAIT_CMD		(900*HZ)

/*
 *	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 sytem
 *	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 will service requests from
 *		the other device on the same interface meanwhile.
 *
 *	2.	After the successful initialization of a "media access
 *		packet command", which is a command which can take a long
 *		time to complete (it can be several seconds or 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 (one second), and if we don't receive DSC
 *		after IDETAPE_DSC_MA_THRESHOLD (5 minutes), we switch it to a
 *		lower frequency - IDETAPE_DSC_MA_SLOW (1 minute).
 *
 *	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 ***********************/

/*
 *	Debugging/Performance analysis
 *
 *	I/O trace support
 */
#define USE_IOTRACE	0
#if USE_IOTRACE
#include <linux/io_trace.h>
#define IO_IDETAPE_FIFO	500
#endif

/*
 *	Read/Write error simulation
 */
#define SIMULATE_ERRORS			0

/*
 *	For general magnetic tape device compatibility.
 */
typedef enum {
	idetape_direction_none,
	idetape_direction_read,
	idetape_direction_write
} idetape_chrdev_direction_t;

struct idetape_bh {
	unsigned short b_size;
	atomic_t b_count;
	struct idetape_bh *b_reqnext;
	char *b_data;
};

/*
 *	Our view of a packet command.
 */
typedef struct idetape_packet_command_s {
	u8 c[12];				/* Actual packet bytes */
	int retries;				/* On each retry, we increment retries */
	int error;				/* Error code */
	int request_transfer;			/* Bytes to transfer */
	int actually_transferred;		/* Bytes actually transferred */
	int buffer_size;			/* Size of our data buffer */
	struct idetape_bh *bh;
	char *b_data;
	int b_count;
	u8 *buffer;				/* Data buffer */
	u8 *current_position;			/* Pointer into the above buffer */
	ide_startstop_t (*callback) (ide_drive_t *);	/* Called when this packet command is completed */
	u8 pc_buffer[IDETAPE_PC_BUFFER_SIZE];	/* Temporary buffer */
	unsigned long flags;			/* Status/Action bit flags: long for set_bit */
} idetape_pc_t;

/*
 *	Packet command flag bits.
 */
/* Set when an error is considered normal - We won't retry */
#define	PC_ABORT			0
/* 1 When polling for DSC on a media access command */
#define PC_WAIT_FOR_DSC			1
/* 1 when we prefer to use DMA if possible */
#define PC_DMA_RECOMMENDED		2
/* 1 while DMA in progress */
#define	PC_DMA_IN_PROGRESS		3
/* 1 when encountered problem during DMA */
#define	PC_DMA_ERROR			4
/* Data direction */
#define	PC_WRITING			5

/*
 *	Capabilities and Mechanical Status Page
 */
typedef struct {
	unsigned	page_code	:6;	/* Page code - Should be 0x2a */
	__u8		reserved0_6	:1;
	__u8		ps		:1;	/* parameters saveable */
	__u8		page_length;		/* Page Length - Should be 0x12 */
	__u8		reserved2, reserved3;
	unsigned	ro		:1;	/* Read Only Mode */
	unsigned	reserved4_1234	:4;
	unsigned	sprev		:1;	/* Supports SPACE in the reverse direction */
	unsigned	reserved4_67	:2;
	unsigned	reserved5_012	:3;
	unsigned	efmt		:1;	/* Supports ERASE command initiated formatting */
	unsigned	reserved5_4	:1;
	unsigned	qfa		:1;	/* Supports the QFA two partition formats */
	unsigned	reserved5_67	:2;
	unsigned	lock		:1;	/* Supports locking the volume */
	unsigned	locked		:1;	/* The volume is locked */
	unsigned	prevent		:1;	/* The device defaults in the prevent state after power up */	
	unsigned	eject		:1;	/* The device can eject the volume */
	__u8		disconnect	:1;	/* The device can break request > ctl */	
	__u8		reserved6_5	:1;
	unsigned	ecc		:1;	/* Supports error correction */
	unsigned	cmprs		:1;	/* Supports data compression */
	unsigned	reserved7_0	:1;
	unsigned	blk512		:1;	/* Supports 512 bytes block size */
	unsigned	blk1024		:1;	/* Supports 1024 bytes block size */
	unsigned	reserved7_3_6	:4;
	unsigned	blk32768	:1;	/* slowb - the device restricts the byte count for PIO */
						/* transfers for slow buffer memory ??? */
						/* Also 32768 block size in some cases */
	__u16		max_speed;		/* Maximum speed supported in KBps */
	__u8		reserved10, reserved11;
	__u16		ctl;			/* Continuous Transfer Limit in blocks */
	__u16		speed;			/* Current Speed, in KBps */
	__u16		buffer_size;		/* Buffer Size, in 512 bytes */
	__u8		reserved18, reserved19;
} idetape_capabilities_page_t;

/*
 *	Block Size Page
 */
typedef struct {
	unsigned	page_code	:6;	/* Page code - Should be 0x30 */
	unsigned	reserved1_6	:1;
	unsigned	ps		:1;
	__u8		page_length;		/* Page Length - Should be 2 */
	__u8		reserved2;
	unsigned	play32		:1;
	unsigned	play32_5	:1;
	unsigned	reserved2_23	:2;
	unsigned	record32	:1;
	unsigned	record32_5	:1;
	unsigned	reserved2_6	:1;
	unsigned	one		:1;
} idetape_block_size_page_t;

/*
 *	A pipeline stage.
 */
typedef struct idetape_stage_s {
	struct request rq;			/* The corresponding request */
	struct idetape_bh *bh;			/* The data buffers */
	struct idetape_stage_s *next;		/* Pointer to the next stage */
} idetape_stage_t;

/*
 *	REQUEST SENSE packet command result - Data Format.
 */
typedef struct {
	unsigned	error_code	:7;	/* Current of deferred errors */
	unsigned	valid		:1;	/* The information field conforms to QIC-157C */
	__u8		reserved1	:8;	/* Segment Number - Reserved */
	unsigned	sense_key	:4;	/* Sense Key */
	unsigned	reserved2_4	:1;	/* Reserved */
	unsigned	ili		:1;	/* Incorrect Length Indicator */
	unsigned	eom		:1;	/* End Of Medium */
	unsigned	filemark 	:1;	/* Filemark */
	__u32		information __attribute__ ((packed));
	__u8		asl;			/* Additional sense length (n-7) */
	__u32		command_specific;	/* Additional command specific information */
	__u8		asc;			/* Additional Sense Code */
	__u8		ascq;			/* Additional Sense Code Qualifier */
	__u8		replaceable_unit_code;	/* Field Replaceable Unit Code */
	unsigned	sk_specific1 	:7;	/* Sense Key Specific */
	unsigned	sksv		:1;	/* Sense Key Specific information is valid */
	__u8		sk_specific2;		/* Sense Key Specific */
	__u8		sk_specific3;		/* Sense Key Specific */
	__u8		pad[2];			/* Padding to 20 bytes */
} idetape_request_sense_result_t;


/*
 *	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 a variable
 *	of type idetape_tape_t, defined below.
 */
typedef struct ide_tape_obj {
	ide_drive_t	*drive;
	ide_driver_t	*driver;
	struct gendisk	*disk;
	struct kref	kref;

	/*
	 *	Since a typical character device operation requires more
	 *	than one packet command, we provide here enough memory
	 *	for the maximum of interconnected packet commands.
	 *	The packet commands are stored in the circular array pc_stack.
	 *	pc_stack_index points to the last used entry, and warps around
	 *	to the start when we get to the last array entry.
	 *
	 *	pc points to the current processed packet command.
	 *
	 *	failed_pc points to the last failed packet command, or contains
	 *	NULL if we do not need to retry any packet command. This is
	 *	required since an additional packet command is needed before the
	 *	retry, to get detailed information on what went wrong.
	 */
	/* Current packet command */
	idetape_pc_t *pc;
	/* Last failed packet command */
	idetape_pc_t *failed_pc;
	/* Packet command stack */
	idetape_pc_t pc_stack[IDETAPE_PC_STACK];
	/* Next free packet command storage space */
	int pc_stack_index;
	struct request rq_stack[IDETAPE_PC_STACK];
	/* We implement a circular array */
	int rq_stack_index;

	/*
	 *	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. Additional requests can be
	 *	queued in our internal pipeline, but they will be visible
	 *	to ide.c only one at a time.
	 */
	struct request *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_frequency;
	/* The current polling frequency */
	unsigned long dsc_polling_frequency;
	/* Maximum waiting time */
	unsigned long dsc_timeout;

	/*
	 *	Read position information
	 */
	u8 partition;
	/* Current block */
	unsigned int first_frame_position;
	unsigned int last_frame_position;
	unsigned int blocks_in_buffer;

	/*
	 *	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 */
	idetape_chrdev_direction_t chrdev_direction;

	/*
	 *	Device information
	 */
	/* Usually 512 or 1024 bytes */
	unsigned short tape_block_size;
	int user_bs_factor;
	/* Copy of the tape's Capabilities and Mechanical Page */
	idetape_capabilities_page_t capabilities;

	/*
	 *	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. In the pipelined operation
	 *	mode, we use our internal pipeline structure to hold
	 *	more data requests.
	 *
	 *	The data buffer size is chosen based on the tape's
	 *	recommendation.
	 */
	/* Pointer to the request which is waiting in the device request queue */
	struct request *active_data_request;
	/* Data buffer size (chosen based on the tape's recommendation */
	int stage_size;
	idetape_stage_t *merge_stage;
	int merge_stage_size;
	struct idetape_bh *bh;
	char *b_data;
	int b_count;
	
	/*
	 *	Pipeline parameters.
	 *
	 *	To accomplish non-pipelined mode, we simply set the following
	 *	variables to zero (or NULL, where appropriate).
	 */
	/* Number of currently used stages */
	int nr_stages;
	/* Number of pending stages */
	int nr_pending_stages;
	/* We will not allocate more than this number of stages */
	int max_stages, min_pipeline, max_pipeline;
	/* The first stage which will be removed from the pipeline */
	idetape_stage_t *first_stage;
	/* The currently active stage */
	idetape_stage_t *active_stage;
	/* Will be serviced after the currently active request */
	idetape_stage_t *next_stage;
	/* New requests will be added to the pipeline here */
	idetape_stage_t *last_stage;
	/* Optional free stage which we can use */
	idetape_stage_t *cache_stage;
	int pages_per_stage;
	/* Wasted space in each stage */
	int excess_bh_size;

	/* Status/Action flags: long for set_bit */
	unsigned long flags;
	/* protects the ide-tape queue */
	spinlock_t spinlock;

	/*
	 * Measures average tape speed
	 */
	unsigned long avg_time;
	int avg_size;
	int avg_speed;

	/* last sense information */
	idetape_request_sense_result_t sense;

	char vendor_id[10];
	char product_id[18];
	char firmware_revision[6];
	int firmware_revision_num;

	/* 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;

	/*
	 * Limit the number of times a request can
	 * be postponed, to avoid an infinite postpone
	 * deadlock.
	 */
	/* request postpone count limit */
	int postpone_cnt;

	/*
	 * Measures number of frames:
	 *
	 * 1. written/read to/from the driver pipeline (pipeline_head).
	 * 2. written/read to/from the tape buffers (idetape_bh).
	 * 3. written/read by the tape to/from the media (tape_head).
	 */
	int pipeline_head;
	int buffer_head;
	int tape_head;
	int last_tape_head;

	/*
	 * Speed control at the tape buffers input/output
	 */
	unsigned long insert_time;
	int insert_size;
	int insert_speed;
	int max_insert_speed;
	int measure_insert_time;

	/*
	 * Measure tape still time, in milliseconds
	 */
	unsigned long tape_still_time_begin;
	int tape_still_time;

	/*
	 * Speed regulation negative feedback loop
	 */
	int speed_control;
	int pipeline_head_speed;
	int controlled_pipeline_head_speed;
	int uncontrolled_pipeline_head_speed;
	int controlled_last_pipeline_head;
	int uncontrolled_last_pipeline_head;
	unsigned long uncontrolled_pipeline_head_time;
	unsigned long controlled_pipeline_head_time;
	int controlled_previous_pipeline_head;
	int uncontrolled_previous_pipeline_head;
	unsigned long controlled_previous_head_time;
	unsigned long uncontrolled_previous_head_time;
	int restart_speed_control_req;

        /*
         * Debug_level determines amount of debugging output;
         * can be changed using /proc/ide/hdx/settings
         * 0 : almost no debugging output
         * 1 : 0+output errors only
         * 2 : 1+output all sensekey/asc
         * 3 : 2+follow all chrdev related procedures
         * 4 : 3+follow all procedures
         * 5 : 4+include pc_stack rq_stack info
         * 6 : 5+USE_COUNT updates
         */
         int debug_level; 
} idetape_tape_t;

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static DEFINE_MUTEX(idetape_ref_mutex);
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static struct class *idetape_sysfs_class;

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#define to_ide_tape(obj) container_of(obj, struct ide_tape_obj, kref)

#define ide_tape_g(disk) \
	container_of((disk)->private_data, struct ide_tape_obj, driver)

static struct ide_tape_obj *ide_tape_get(struct gendisk *disk)
{
	struct ide_tape_obj *tape = NULL;

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	mutex_lock(&idetape_ref_mutex);
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	tape = ide_tape_g(disk);
	if (tape)
		kref_get(&tape->kref);
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	mutex_unlock(&idetape_ref_mutex);
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	return tape;
}

static void ide_tape_release(struct kref *);

static void ide_tape_put(struct ide_tape_obj *tape)
{
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	mutex_lock(&idetape_ref_mutex);
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	kref_put(&tape->kref, ide_tape_release);
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	mutex_unlock(&idetape_ref_mutex);
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}

/*
 *	Tape door status
 */
#define DOOR_UNLOCKED			0
#define DOOR_LOCKED			1
#define DOOR_EXPLICITLY_LOCKED		2

/*
 *	Tape flag bits values.
 */
#define IDETAPE_IGNORE_DSC		0
#define IDETAPE_ADDRESS_VALID		1	/* 0 When the tape position is unknown */
#define IDETAPE_BUSY			2	/* Device already opened */
#define IDETAPE_PIPELINE_ERROR		3	/* Error detected in a pipeline stage */
#define IDETAPE_DETECT_BS		4	/* Attempt to auto-detect the current user block size */
#define IDETAPE_FILEMARK		5	/* Currently on a filemark */
#define IDETAPE_DRQ_INTERRUPT		6	/* DRQ interrupt device */
#define IDETAPE_READ_ERROR		7
#define IDETAPE_PIPELINE_ACTIVE		8	/* pipeline active */
/* 0 = no tape is loaded, so we don't rewind after ejecting */
#define IDETAPE_MEDIUM_PRESENT		9

/*
 *	Supported ATAPI tape drives packet commands
 */
#define IDETAPE_TEST_UNIT_READY_CMD	0x00
#define IDETAPE_REWIND_CMD		0x01
#define IDETAPE_REQUEST_SENSE_CMD	0x03
#define IDETAPE_READ_CMD		0x08
#define IDETAPE_WRITE_CMD		0x0a
#define IDETAPE_WRITE_FILEMARK_CMD	0x10
#define IDETAPE_SPACE_CMD		0x11
#define IDETAPE_INQUIRY_CMD		0x12
#define IDETAPE_ERASE_CMD		0x19
#define IDETAPE_MODE_SENSE_CMD		0x1a
#define IDETAPE_MODE_SELECT_CMD		0x15
#define IDETAPE_LOAD_UNLOAD_CMD		0x1b
#define IDETAPE_PREVENT_CMD		0x1e
#define IDETAPE_LOCATE_CMD		0x2b
#define IDETAPE_READ_POSITION_CMD	0x34
#define IDETAPE_READ_BUFFER_CMD		0x3c
#define IDETAPE_SET_SPEED_CMD		0xbb

/*
 *	Some defines for the READ BUFFER command
 */
#define IDETAPE_RETRIEVE_FAULTY_BLOCK	6

/*
 *	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

/*
 *	Special requests for our block device strategy routine.
 *
 *	In order to service a character device command, we add special
 *	requests to the tail of our block device request queue and wait
 *	for their completion.
 */

enum {
	REQ_IDETAPE_PC1		= (1 << 0), /* packet command (first stage) */
	REQ_IDETAPE_PC2		= (1 << 1), /* packet command (second stage) */
	REQ_IDETAPE_READ	= (1 << 2),
	REQ_IDETAPE_WRITE	= (1 << 3),
	REQ_IDETAPE_READ_BUFFER	= (1 << 4),
};

/*
 *	Error codes which are returned in rq->errors to the higher part
 *	of the driver.
 */
#define	IDETAPE_ERROR_GENERAL		101
#define	IDETAPE_ERROR_FILEMARK		102
#define	IDETAPE_ERROR_EOD		103

/*
 *	The following is used to format the general configuration word of
 *	the ATAPI IDENTIFY DEVICE command.
 */
struct idetape_id_gcw {	
	unsigned packet_size		:2;	/* Packet Size */
	unsigned reserved234		:3;	/* Reserved */
	unsigned drq_type		:2;	/* Command packet DRQ type */
	unsigned removable		:1;	/* Removable media */
	unsigned device_type		:5;	/* Device type */
	unsigned reserved13		:1;	/* Reserved */
	unsigned protocol		:2;	/* Protocol type */
};

/*
 *	INQUIRY packet command - Data Format (From Table 6-8 of QIC-157C)
 */
typedef struct {
	unsigned	device_type	:5;	/* Peripheral Device Type */
	unsigned	reserved0_765	:3;	/* Peripheral Qualifier - Reserved */
	unsigned	reserved1_6t0	:7;	/* Reserved */
	unsigned	rmb		:1;	/* Removable Medium Bit */
	unsigned	ansi_version	:3;	/* ANSI Version */
	unsigned	ecma_version	:3;	/* ECMA Version */
	unsigned	iso_version	:2;	/* ISO Version */
	unsigned	response_format :4;	/* Response Data Format */
	unsigned	reserved3_45	:2;	/* Reserved */
	unsigned	reserved3_6	:1;	/* TrmIOP - Reserved */
	unsigned	reserved3_7	:1;	/* AENC - Reserved */
	__u8		additional_length;	/* Additional Length (total_length-4) */
	__u8		rsv5, rsv6, rsv7;	/* Reserved */
	__u8		vendor_id[8];		/* Vendor Identification */
	__u8		product_id[16];		/* Product Identification */
	__u8		revision_level[4];	/* Revision Level */
	__u8		vendor_specific[20];	/* Vendor Specific - Optional */
	__u8		reserved56t95[40];	/* Reserved - Optional */
						/* Additional information may be returned */
} idetape_inquiry_result_t;

/*
 *	READ POSITION packet command - Data Format (From Table 6-57)
 */
typedef struct {
	unsigned	reserved0_10	:2;	/* Reserved */
	unsigned	bpu		:1;	/* Block Position Unknown */	
	unsigned	reserved0_543	:3;	/* Reserved */
	unsigned	eop		:1;	/* End Of Partition */
	unsigned	bop		:1;	/* Beginning Of Partition */
	u8		partition;		/* Partition Number */
	u8		reserved2, reserved3;	/* Reserved */
	u32		first_block;		/* First Block Location */
	u32		last_block;		/* Last Block Location (Optional) */
	u8		reserved12;		/* Reserved */
	u8		blocks_in_buffer[3];	/* Blocks In Buffer - (Optional) */
	u32		bytes_in_buffer;	/* Bytes In Buffer (Optional) */
} idetape_read_position_result_t;

/*
 *	Follows structures which are related to the SELECT SENSE / MODE SENSE
 *	packet commands. Those packet commands are still not supported
 *	by ide-tape.
 */
#define IDETAPE_BLOCK_DESCRIPTOR	0
#define	IDETAPE_CAPABILITIES_PAGE	0x2a
#define IDETAPE_PARAMTR_PAGE		0x2b   /* Onstream DI-x0 only */
#define IDETAPE_BLOCK_SIZE_PAGE		0x30
#define IDETAPE_BUFFER_FILLING_PAGE	0x33

/*
 *	Mode Parameter Header for the MODE SENSE packet command
 */
typedef struct {
	__u8	mode_data_length;	/* Length of the following data transfer */
	__u8	medium_type;		/* Medium Type */
	__u8	dsp;			/* Device Specific Parameter */
	__u8	bdl;			/* Block Descriptor Length */
#if 0
	/* data transfer page */
	__u8	page_code	:6;
	__u8	reserved0_6	:1;
	__u8	ps		:1;	/* parameters saveable */
	__u8	page_length;		/* page Length == 0x02 */
	__u8	reserved2;
	__u8	read32k		:1;	/* 32k blk size (data only) */
	__u8	read32k5	:1;	/* 32.5k blk size (data&AUX) */
	__u8	reserved3_23	:2;
	__u8	write32k	:1;	/* 32k blk size (data only) */
	__u8	write32k5	:1;	/* 32.5k blk size (data&AUX) */
	__u8	reserved3_6	:1;
	__u8	streaming	:1;	/* streaming mode enable */
#endif
} idetape_mode_parameter_header_t;

/*
 *	Mode Parameter Block Descriptor the MODE SENSE packet command
 *
 *	Support for block descriptors is optional.
 */
typedef struct {
	__u8		density_code;		/* Medium density code */
	__u8		blocks[3];		/* Number of blocks */
	__u8		reserved4;		/* Reserved */
	__u8		length[3];		/* Block Length */
} idetape_parameter_block_descriptor_t;

/*
 *	The Data Compression Page, as returned by the MODE SENSE packet command.
 */
typedef struct {
	unsigned	page_code	:6;	/* Page Code - Should be 0xf */
	unsigned	reserved0	:1;	/* Reserved */
	unsigned	ps		:1;
	__u8		page_length;		/* Page Length - Should be 14 */
	unsigned	reserved2	:6;	/* Reserved */
	unsigned	dcc		:1;	/* Data Compression Capable */
	unsigned	dce		:1;	/* Data Compression Enable */
	unsigned	reserved3	:5;	/* Reserved */
	unsigned	red		:2;	/* Report Exception on Decompression */
	unsigned	dde		:1;	/* Data Decompression Enable */
	__u32		ca;			/* Compression Algorithm */
	__u32		da;			/* Decompression Algorithm */
	__u8		reserved[4];		/* Reserved */
} idetape_data_compression_page_t;

/*
 *	The Medium Partition Page, as returned by the MODE SENSE packet command.
 */
typedef struct {
	unsigned	page_code	:6;	/* Page Code - Should be 0x11 */
	unsigned	reserved1_6	:1;	/* Reserved */
	unsigned	ps		:1;
	__u8		page_length;		/* Page Length - Should be 6 */
	__u8		map;			/* Maximum Additional Partitions - Should be 0 */
	__u8		apd;			/* Additional Partitions Defined - Should be 0 */
	unsigned	reserved4_012	:3;	/* Reserved */
	unsigned	psum		:2;	/* Should be 0 */
	unsigned	idp		:1;	/* Should be 0 */
	unsigned	sdp		:1;	/* Should be 0 */
	unsigned	fdp		:1;	/* Fixed Data Partitions */
	__u8		mfr;			/* Medium Format Recognition */
	__u8		reserved[2];		/* Reserved */
} idetape_medium_partition_page_t;

/*
 *	Run time configurable parameters.
 */
typedef struct {
	int	dsc_rw_frequency;
	int	dsc_media_access_frequency;
	int	nr_stages;
} idetape_config_t;

/*
 *	The variables below are used for the character device interface.
 *	Additional state variables are defined in our ide_drive_t structure.
 */
static struct ide_tape_obj * idetape_devs[MAX_HWIFS * MAX_DRIVES];

#define ide_tape_f(file) ((file)->private_data)

static struct ide_tape_obj *ide_tape_chrdev_get(unsigned int i)
{
	struct ide_tape_obj *tape = NULL;

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	mutex_lock(&idetape_ref_mutex);
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	tape = idetape_devs[i];
	if (tape)
		kref_get(&tape->kref);
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	mutex_unlock(&idetape_ref_mutex);
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	return tape;
}

/*
 *      Function declarations
 *
 */
static int idetape_chrdev_release (struct inode *inode, struct file *filp);
static void idetape_write_release (ide_drive_t *drive, unsigned int minor);

/*
 * Too bad. The drive wants to send us data which we are not ready to accept.
 * Just throw it away.
 */
static void idetape_discard_data (ide_drive_t *drive, unsigned int bcount)
{
	while (bcount--)
		(void) HWIF(drive)->INB(IDE_DATA_REG);
}

static void idetape_input_buffers (ide_drive_t *drive, idetape_pc_t *pc, unsigned int bcount)
{
	struct idetape_bh *bh = pc->bh;
	int count;

	while (bcount) {
#if IDETAPE_DEBUG_BUGS
		if (bh == NULL) {
			printk(KERN_ERR "ide-tape: bh == NULL in "
				"idetape_input_buffers\n");
			idetape_discard_data(drive, bcount);
			return;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		count = min((unsigned int)(bh->b_size - atomic_read(&bh->b_count)), bcount);
		HWIF(drive)->atapi_input_bytes(drive, bh->b_data + atomic_read(&bh->b_count), count);
		bcount -= count;
		atomic_add(count, &bh->b_count);
		if (atomic_read(&bh->b_count) == bh->b_size) {
			bh = bh->b_reqnext;
			if (bh)
				atomic_set(&bh->b_count, 0);
		}
	}
	pc->bh = bh;
}

static void idetape_output_buffers (ide_drive_t *drive, idetape_pc_t *pc, unsigned int bcount)
{
	struct idetape_bh *bh = pc->bh;
	int count;

	while (bcount) {
#if IDETAPE_DEBUG_BUGS
		if (bh == NULL) {
			printk(KERN_ERR "ide-tape: bh == NULL in "
				"idetape_output_buffers\n");
			return;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		count = min((unsigned int)pc->b_count, (unsigned int)bcount);
		HWIF(drive)->atapi_output_bytes(drive, pc->b_data, count);
		bcount -= count;
		pc->b_data += count;
		pc->b_count -= count;
		if (!pc->b_count) {
			pc->bh = bh = bh->b_reqnext;
			if (bh) {
				pc->b_data = bh->b_data;
				pc->b_count = atomic_read(&bh->b_count);
			}
		}
	}
}

static void idetape_update_buffers (idetape_pc_t *pc)
{
	struct idetape_bh *bh = pc->bh;
	int count;
	unsigned int bcount = pc->actually_transferred;

	if (test_bit(PC_WRITING, &pc->flags))
		return;
	while (bcount) {
#if IDETAPE_DEBUG_BUGS
		if (bh == NULL) {
			printk(KERN_ERR "ide-tape: bh == NULL in "
				"idetape_update_buffers\n");
			return;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		count = min((unsigned int)bh->b_size, (unsigned int)bcount);
		atomic_set(&bh->b_count, count);
		if (atomic_read(&bh->b_count) == bh->b_size)
			bh = bh->b_reqnext;
		bcount -= count;
	}
	pc->bh = bh;
}

/*
 *	idetape_next_pc_storage returns a pointer to a place in which we can
 *	safely store a packet command, even though we intend to leave the
 *	driver. A storage space for a maximum of IDETAPE_PC_STACK packet
 *	commands is allocated at initialization time.
 */
static idetape_pc_t *idetape_next_pc_storage (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 5)
		printk(KERN_INFO "ide-tape: pc_stack_index=%d\n",
			tape->pc_stack_index);
#endif /* IDETAPE_DEBUG_LOG */
	if (tape->pc_stack_index == IDETAPE_PC_STACK)
		tape->pc_stack_index=0;
	return (&tape->pc_stack[tape->pc_stack_index++]);
}

/*
 *	idetape_next_rq_storage is used along with idetape_next_pc_storage.
 *	Since we queue packet commands in the request queue, we need to
 *	allocate a request, along with the allocation of a packet command.
 */
 
/**************************************************************
 *                                                            *
 *  This should get fixed to use kmalloc(.., GFP_ATOMIC)      *
 *  followed later on by kfree().   -ml                       *
 *                                                            *
 **************************************************************/
 
static struct request *idetape_next_rq_storage (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 5)
		printk(KERN_INFO "ide-tape: rq_stack_index=%d\n",
			tape->rq_stack_index);
#endif /* IDETAPE_DEBUG_LOG */
	if (tape->rq_stack_index == IDETAPE_PC_STACK)
		tape->rq_stack_index=0;
	return (&tape->rq_stack[tape->rq_stack_index++]);
}

/*
 *	idetape_init_pc initializes a packet command.
 */
static void idetape_init_pc (idetape_pc_t *pc)
{
	memset(pc->c, 0, 12);
	pc->retries = 0;
	pc->flags = 0;
	pc->request_transfer = 0;
	pc->buffer = pc->pc_buffer;
	pc->buffer_size = IDETAPE_PC_BUFFER_SIZE;
	pc->bh = NULL;
	pc->b_data = NULL;
}

/*
 *	idetape_analyze_error is 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_request_sense_result_t *result)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t *pc = tape->failed_pc;

	tape->sense     = *result;
	tape->sense_key = result->sense_key;
	tape->asc       = result->asc;
	tape->ascq      = result->ascq;
#if IDETAPE_DEBUG_LOG
	/*
	 *	Without debugging, we only log an error if we decided to
	 *	give up retrying.
	 */
	if (tape->debug_level >= 1)
		printk(KERN_INFO "ide-tape: pc = %x, sense key = %x, "
			"asc = %x, ascq = %x\n",
			pc->c[0], result->sense_key,
			result->asc, result->ascq);
#endif /* IDETAPE_DEBUG_LOG */

	/*
	 *	Correct pc->actually_transferred by asking the tape.
	 */
	if (test_bit(PC_DMA_ERROR, &pc->flags)) {
		pc->actually_transferred = pc->request_transfer - tape->tape_block_size * ntohl(get_unaligned(&result->information));
		idetape_update_buffers(pc);
	}

	/*
	 * 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] == IDETAPE_READ_CMD || pc->c[0] == IDETAPE_WRITE_CMD)
	    && pc->c[4] == 0 && pc->c[3] == 0 && pc->c[2] == 0) { /* length==0 */
		if (result->sense_key == 5) {
			/* don't report an error, everything's ok */
			pc->error = 0;
			/* don't retry read/write */
			set_bit(PC_ABORT, &pc->flags);
		}
	}
	if (pc->c[0] == IDETAPE_READ_CMD && result->filemark) {
		pc->error = IDETAPE_ERROR_FILEMARK;
		set_bit(PC_ABORT, &pc->flags);
	}
	if (pc->c[0] == IDETAPE_WRITE_CMD) {
		if (result->eom ||
		    (result->sense_key == 0xd && result->asc == 0x0 &&
		     result->ascq == 0x2)) {
			pc->error = IDETAPE_ERROR_EOD;
			set_bit(PC_ABORT, &pc->flags);
		}
	}
	if (pc->c[0] == IDETAPE_READ_CMD || pc->c[0] == IDETAPE_WRITE_CMD) {
		if (result->sense_key == 8) {
			pc->error = IDETAPE_ERROR_EOD;
			set_bit(PC_ABORT, &pc->flags);
		}
		if (!test_bit(PC_ABORT, &pc->flags) &&
		    pc->actually_transferred)
			pc->retries = IDETAPE_MAX_PC_RETRIES + 1;
	}
}

/*
 * idetape_active_next_stage will declare the next stage as "active".
 */
static void idetape_active_next_stage (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *stage = tape->next_stage;
	struct request *rq = &stage->rq;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_active_next_stage\n");
#endif /* IDETAPE_DEBUG_LOG */
#if IDETAPE_DEBUG_BUGS
	if (stage == NULL) {
		printk(KERN_ERR "ide-tape: bug: Trying to activate a non existing stage\n");
		return;
	}
#endif /* IDETAPE_DEBUG_BUGS */	

	rq->rq_disk = tape->disk;
	rq->buffer = NULL;
	rq->special = (void *)stage->bh;
	tape->active_data_request = rq;
	tape->active_stage = stage;
	tape->next_stage = stage->next;
}

/*
 *	idetape_increase_max_pipeline_stages is a part of the feedback
 *	loop which tries to find the optimum number of stages. In the
 *	feedback loop, we are starting from a minimum maximum number of
 *	stages, and if we sense that the pipeline is empty, we try to
 *	increase it, until we reach the user compile time memory limit.
 */
static void idetape_increase_max_pipeline_stages (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	int increase = (tape->max_pipeline - tape->min_pipeline) / 10;
	
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk (KERN_INFO "ide-tape: Reached idetape_increase_max_pipeline_stages\n");
#endif /* IDETAPE_DEBUG_LOG */

	tape->max_stages += max(increase, 1);
	tape->max_stages = max(tape->max_stages, tape->min_pipeline);
	tape->max_stages = min(tape->max_stages, tape->max_pipeline);
}

/*
 *	idetape_kfree_stage calls kfree to completely free a stage, along with
 *	its related buffers.
 */
static void __idetape_kfree_stage (idetape_stage_t *stage)
{
	struct idetape_bh *prev_bh, *bh = stage->bh;
	int size;

	while (bh != NULL) {
		if (bh->b_data != NULL) {
			size = (int) bh->b_size;
			while (size > 0) {
				free_page((unsigned long) bh->b_data);
				size -= PAGE_SIZE;
				bh->b_data += PAGE_SIZE;
			}
		}
		prev_bh = bh;
		bh = bh->b_reqnext;
		kfree(prev_bh);
	}
	kfree(stage);
}

static void idetape_kfree_stage (idetape_tape_t *tape, idetape_stage_t *stage)
{
	__idetape_kfree_stage(stage);
}

/*
 *	idetape_remove_stage_head removes tape->first_stage from the pipeline.
 *	The caller should avoid race conditions.
 */
static void idetape_remove_stage_head (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *stage;
	
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_remove_stage_head\n");
#endif /* IDETAPE_DEBUG_LOG */
#if IDETAPE_DEBUG_BUGS
	if (tape->first_stage == NULL) {
		printk(KERN_ERR "ide-tape: bug: tape->first_stage is NULL\n");
		return;		
	}
	if (tape->active_stage == tape->first_stage) {
		printk(KERN_ERR "ide-tape: bug: Trying to free our active pipeline stage\n");
		return;
	}
#endif /* IDETAPE_DEBUG_BUGS */
	stage = tape->first_stage;
	tape->first_stage = stage->next;
	idetape_kfree_stage(tape, stage);
	tape->nr_stages--;
	if (tape->first_stage == NULL) {
		tape->last_stage = NULL;
#if IDETAPE_DEBUG_BUGS
		if (tape->next_stage != NULL)
			printk(KERN_ERR "ide-tape: bug: tape->next_stage != NULL\n");
		if (tape->nr_stages)
			printk(KERN_ERR "ide-tape: bug: nr_stages should be 0 now\n");
#endif /* IDETAPE_DEBUG_BUGS */
	}
}

/*
 * This will free all the pipeline stages starting from new_last_stage->next
 * to the end of the list, and point tape->last_stage to new_last_stage.
 */
static void idetape_abort_pipeline(ide_drive_t *drive,
				   idetape_stage_t *new_last_stage)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *stage = new_last_stage->next;
	idetape_stage_t *nstage;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: %s: idetape_abort_pipeline called\n", tape->name);
#endif
	while (stage) {
		nstage = stage->next;
		idetape_kfree_stage(tape, stage);
		--tape->nr_stages;
		--tape->nr_pending_stages;
		stage = nstage;
	}
	if (new_last_stage)
		new_last_stage->next = NULL;
	tape->last_stage = new_last_stage;
	tape->next_stage = NULL;
}

/*
 *	idetape_end_request is used to finish servicing a request, and to
 *	insert a pending pipeline request into the main device queue.
 */
static int idetape_end_request(ide_drive_t *drive, int uptodate, int nr_sects)
{
	struct request *rq = HWGROUP(drive)->rq;
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;
	int error;
	int remove_stage = 0;
	idetape_stage_t *active_stage;

#if IDETAPE_DEBUG_LOG
        if (tape->debug_level >= 4)
	printk(KERN_INFO "ide-tape: Reached idetape_end_request\n");
#endif /* IDETAPE_DEBUG_LOG */

	switch (uptodate) {
		case 0:	error = IDETAPE_ERROR_GENERAL; break;
		case 1: error = 0; break;
		default: error = uptodate;
	}
	rq->errors = error;
	if (error)
		tape->failed_pc = NULL;

	spin_lock_irqsave(&tape->spinlock, flags);

	/* The request was a pipelined data transfer request */
	if (tape->active_data_request == rq) {
		active_stage = tape->active_stage;
		tape->active_stage = NULL;
		tape->active_data_request = NULL;
		tape->nr_pending_stages--;
		if (rq->cmd[0] & REQ_IDETAPE_WRITE) {
			remove_stage = 1;
			if (error) {
				set_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
				if (error == IDETAPE_ERROR_EOD)
					idetape_abort_pipeline(drive, active_stage);
			}
		} else if (rq->cmd[0] & REQ_IDETAPE_READ) {
			if (error == IDETAPE_ERROR_EOD) {
				set_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
				idetape_abort_pipeline(drive, active_stage);
			}
		}
		if (tape->next_stage != NULL) {
			idetape_active_next_stage(drive);

			/*
			 * Insert the next request into the request queue.
			 */
			(void) ide_do_drive_cmd(drive, tape->active_data_request, ide_end);
		} else if (!error) {
				idetape_increase_max_pipeline_stages(drive);
		}
	}
	ide_end_drive_cmd(drive, 0, 0);
//	blkdev_dequeue_request(rq);
//	drive->rq = NULL;
//	end_that_request_last(rq);

	if (remove_stage)
		idetape_remove_stage_head(drive);
	if (tape->active_data_request == NULL)
		clear_bit(IDETAPE_PIPELINE_ACTIVE, &tape->flags);
	spin_unlock_irqrestore(&tape->spinlock, flags);
	return 0;
}

static ide_startstop_t idetape_request_sense_callback (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_request_sense_callback\n");
#endif /* IDETAPE_DEBUG_LOG */
	if (!tape->pc->error) {
		idetape_analyze_error(drive, (idetape_request_sense_result_t *) tape->pc->buffer);
		idetape_end_request(drive, 1, 0);
	} else {
		printk(KERN_ERR "ide-tape: Error in REQUEST SENSE itself - Aborting request!\n");
		idetape_end_request(drive, 0, 0);
	}
	return ide_stopped;
}

static void idetape_create_request_sense_cmd (idetape_pc_t *pc)
{
	idetape_init_pc(pc);	
	pc->c[0] = IDETAPE_REQUEST_SENSE_CMD;
	pc->c[4] = 20;
	pc->request_transfer = 20;
	pc->callback = &idetape_request_sense_callback;
}

static void idetape_init_rq(struct request *rq, u8 cmd)
{
	memset(rq, 0, sizeof(*rq));
1779
	rq->cmd_type = REQ_TYPE_SPECIAL;
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	rq->cmd[0] = cmd;
}

/*
 *	idetape_queue_pc_head generates a new packet command request in front
 *	of the request queue, before the current request, so that it will be
 *	processed immediately, on the next pass through the driver.
 *
 *	idetape_queue_pc_head is called from the request handling part of
 *	the driver (the "bottom" part). Safe storage for the request should
 *	be allocated with idetape_next_pc_storage and idetape_next_rq_storage
 *	before calling idetape_queue_pc_head.
 *
 *	Memory for those requests is pre-allocated at initialization time, and
 *	is limited to IDETAPE_PC_STACK requests. We assume that we have enough
 *	space for the maximum possible number of inter-dependent packet commands.
 *
 *	The higher level of the driver - The ioctl handler and the character
 *	device handling functions should queue request to the lower level part
 *	and wait for their completion using idetape_queue_pc_tail or
 *	idetape_queue_rw_tail.
 */
static void idetape_queue_pc_head (ide_drive_t *drive, idetape_pc_t *pc,struct request *rq)
{
	struct ide_tape_obj *tape = drive->driver_data;

	idetape_init_rq(rq, REQ_IDETAPE_PC1);
	rq->buffer = (char *) pc;
	rq->rq_disk = tape->disk;
	(void) ide_do_drive_cmd(drive, rq, ide_preempt);
}

/*
 *	idetape_retry_pc is called when an error was detected during the
 *	last packet command. We queue a request sense packet command in
 *	the head of the request list.
 */
static ide_startstop_t idetape_retry_pc (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t *pc;
	struct request *rq;
	atapi_error_t error;

	error.all = HWIF(drive)->INB(IDE_ERROR_REG);
	pc = idetape_next_pc_storage(drive);
	rq = idetape_next_rq_storage(drive);
	idetape_create_request_sense_cmd(pc);
	set_bit(IDETAPE_IGNORE_DSC, &tape->flags);
	idetape_queue_pc_head(drive, pc, rq);
	return ide_stopped;
}

/*
 *	idetape_postpone_request postpones the current request so that
 *	ide.c will be able to service requests from another device on
 *	the same hwgroup while we are polling for DSC.
 */
static void idetape_postpone_request (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: idetape_postpone_request\n");
#endif
	tape->postponed_rq = HWGROUP(drive)->rq;
	ide_stall_queue(drive, tape->dsc_polling_frequency);
}

/*
 *	idetape_pc_intr is the usual interrupt handler which will be called
 *	during a packet command. We will transfer some of the data (as
 *	requested by the drive) and will re-point interrupt handler to us.
 *	When data transfer is finished, we will act according to the
 *	algorithm described before idetape_issue_packet_command.
 *
 */
static ide_startstop_t idetape_pc_intr (ide_drive_t *drive)
{
	ide_hwif_t *hwif = drive->hwif;
	idetape_tape_t *tape = drive->driver_data;
	atapi_status_t status;
	atapi_bcount_t bcount;
	atapi_ireason_t ireason;
	idetape_pc_t *pc = tape->pc;

	unsigned int temp;
#if SIMULATE_ERRORS
	static int error_sim_count = 0;
#endif

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_pc_intr "
				"interrupt handler\n");
#endif /* IDETAPE_DEBUG_LOG */	

	/* Clear the interrupt */
	status.all = HWIF(drive)->INB(IDE_STATUS_REG);

	if (test_bit(PC_DMA_IN_PROGRESS, &pc->flags)) {
		if (HWIF(drive)->ide_dma_end(drive) || status.b.check) {
			/*
			 * A DMA error is sometimes expected. For example,
			 * if the tape is crossing a filemark during a
			 * READ command, it will issue an irq and position
			 * itself before the filemark, so that only a partial
			 * data transfer will occur (which causes the DMA
			 * error). In that case, we will later ask the tape
			 * how much bytes of the original request were
			 * actually transferred (we can't receive that
			 * information from the DMA engine on most chipsets).
			 */

			/*
			 * On the contrary, a DMA error is never expected;
			 * it usually indicates a hardware error or abort.
			 * If the tape crosses a filemark during a READ
			 * command, it will issue an irq and position itself
			 * after the filemark (not before). Only a partial
			 * data transfer will occur, but no DMA error.
			 * (AS, 19 Apr 2001)
			 */
			set_bit(PC_DMA_ERROR, &pc->flags);
		} else {
			pc->actually_transferred = pc->request_transfer;
			idetape_update_buffers(pc);
		}
#if IDETAPE_DEBUG_LOG
		if (tape->debug_level >= 4)
			printk(KERN_INFO "ide-tape: DMA finished\n");
#endif /* IDETAPE_DEBUG_LOG */
	}

	/* No more interrupts */
	if (!status.b.drq) {
#if IDETAPE_DEBUG_LOG
		if (tape->debug_level >= 2)
			printk(KERN_INFO "ide-tape: Packet command completed, %d bytes transferred\n", pc->actually_transferred);
#endif /* IDETAPE_DEBUG_LOG */
		clear_bit(PC_DMA_IN_PROGRESS, &pc->flags);

		local_irq_enable();

#if SIMULATE_ERRORS
		if ((pc->c[0] == IDETAPE_WRITE_CMD ||
		     pc->c[0] == IDETAPE_READ_CMD) &&
		    (++error_sim_count % 100) == 0) {
			printk(KERN_INFO "ide-tape: %s: simulating error\n",
				tape->name);
			status.b.check = 1;
		}
#endif
		if (status.b.check && pc->c[0] == IDETAPE_REQUEST_SENSE_CMD)
			status.b.check = 0;
		if (status.b.check || test_bit(PC_DMA_ERROR, &pc->flags)) {	/* Error detected */
#if IDETAPE_DEBUG_LOG
			if (tape->debug_level >= 1)
				printk(KERN_INFO "ide-tape: %s: I/O error\n",
					tape->name);
#endif /* IDETAPE_DEBUG_LOG */
			if (pc->c[0] == IDETAPE_REQUEST_SENSE_CMD) {
				printk(KERN_ERR "ide-tape: I/O error in request sense command\n");
				return ide_do_reset(drive);
			}
#if IDETAPE_DEBUG_LOG
			if (tape->debug_level >= 1)
				printk(KERN_INFO "ide-tape: [cmd %x]: check condition\n", pc->c[0]);
#endif
			/* Retry operation */
			return idetape_retry_pc(drive);
		}
		pc->error = 0;
		if (test_bit(PC_WAIT_FOR_DSC, &pc->flags) &&
		    !status.b.dsc) {
			/* Media access command */
			tape->dsc_polling_start = jiffies;
			tape->dsc_polling_frequency = IDETAPE_DSC_MA_FAST;
			tape->dsc_timeout = jiffies + IDETAPE_DSC_MA_TIMEOUT;
			/* Allow ide.c to handle other requests */
			idetape_postpone_request(drive);
			return ide_stopped;
		}
		if (tape->failed_pc == pc)
			tape->failed_pc = NULL;
		/* Command finished - Call the callback function */
		return pc->callback(drive);
	}
	if (test_and_clear_bit(PC_DMA_IN_PROGRESS, &pc->flags)) {
		printk(KERN_ERR "ide-tape: The tape wants to issue more "
				"interrupts in DMA mode\n");
		printk(KERN_ERR "ide-tape: DMA disabled, reverting to PIO\n");
		(void)__ide_dma_off(drive);
		return ide_do_reset(drive);
	}
	/* Get the number of bytes to transfer on this interrupt. */
	bcount.b.high = hwif->INB(IDE_BCOUNTH_REG);
	bcount.b.low = hwif->INB(IDE_BCOUNTL_REG);

	ireason.all = hwif->INB(IDE_IREASON_REG);

	if (ireason.b.cod) {
		printk(KERN_ERR "ide-tape: CoD != 0 in idetape_pc_intr\n");
		return ide_do_reset(drive);
	}
	if (ireason.b.io == test_bit(PC_WRITING, &pc->flags)) {
		/* Hopefully, we will never get here */
		printk(KERN_ERR "ide-tape: We wanted to %s, ",
			ireason.b.io ? "Write":"Read");
		printk(KERN_ERR "ide-tape: but the tape wants us to %s !\n",
			ireason.b.io ? "Read":"Write");
		return ide_do_reset(drive);
	}
	if (!test_bit(PC_WRITING, &pc->flags)) {
		/* Reading - Check that we have enough space */
		temp = pc->actually_transferred + bcount.all;
		if (temp > pc->request_transfer) {
			if (temp > pc->buffer_size) {
				printk(KERN_ERR "ide-tape: The tape wants to send us more data than expected - discarding data\n");
				idetape_discard_data(drive, bcount.all);
				ide_set_handler(drive, &idetape_pc_intr, IDETAPE_WAIT_CMD, NULL);
				return ide_started;
			}
#if IDETAPE_DEBUG_LOG
			if (tape->debug_level >= 2)
				printk(KERN_NOTICE "ide-tape: The tape wants to send us more data than expected - allowing transfer\n");
#endif /* IDETAPE_DEBUG_LOG */
		}
	}
	if (test_bit(PC_WRITING, &pc->flags)) {
		if (pc->bh != NULL)
			idetape_output_buffers(drive, pc, bcount.all);
		else
			/* Write the current buffer */
			HWIF(drive)->atapi_output_bytes(drive, pc->current_position, bcount.all);
	} else {
		if (pc->bh != NULL)
			idetape_input_buffers(drive, pc, bcount.all);
		else
			/* Read the current buffer */
			HWIF(drive)->atapi_input_bytes(drive, pc->current_position, bcount.all);
	}
	/* Update the current position */
	pc->actually_transferred += bcount.all;
	pc->current_position += bcount.all;
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 2)
		printk(KERN_INFO "ide-tape: [cmd %x] transferred %d bytes on that interrupt\n", pc->c[0], bcount.all);
#endif
	/* And set the interrupt handler again */
	ide_set_handler(drive, &idetape_pc_intr, IDETAPE_WAIT_CMD, NULL);
	return ide_started;
}

/*
 *	Packet Command Interface
 *
 *	The current Packet Command is available in tape->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.	idetape_issue_packet_command will send the packet command to the
 *		drive, and will set the interrupt handler to idetape_pc_intr.
 *
 *	2.	On each interrupt, idetape_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 idetape_transfer_pc(ide_drive_t *drive)
{
	ide_hwif_t *hwif = drive->hwif;
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t *pc = tape->pc;
	atapi_ireason_t ireason;
	int retries = 100;
	ide_startstop_t startstop;

	if (ide_wait_stat(&startstop,drive,DRQ_STAT,BUSY_STAT,WAIT_READY)) {
		printk(KERN_ERR "ide-tape: Strange, packet command initiated yet DRQ isn't asserted\n");
		return startstop;
	}
	ireason.all = hwif->INB(IDE_IREASON_REG);
	while (retries-- && (!ireason.b.cod || ireason.b.io)) {
		printk(KERN_ERR "ide-tape: (IO,CoD != (0,1) while issuing "
				"a packet command, retrying\n");
		udelay(100);
		ireason.all = hwif->INB(IDE_IREASON_REG);
		if (retries == 0) {
			printk(KERN_ERR "ide-tape: (IO,CoD != (0,1) while "
					"issuing a packet command, ignoring\n");
			ireason.b.cod = 1;
			ireason.b.io = 0;
		}
	}
	if (!ireason.b.cod || ireason.b.io) {
		printk(KERN_ERR "ide-tape: (IO,CoD) != (0,1) while issuing "
				"a packet command\n");
		return ide_do_reset(drive);
	}
	/* Set the interrupt routine */
	ide_set_handler(drive, &idetape_pc_intr, IDETAPE_WAIT_CMD, NULL);
#ifdef CONFIG_BLK_DEV_IDEDMA
	/* Begin DMA, if necessary */
	if (test_bit(PC_DMA_IN_PROGRESS, &pc->flags))
		hwif->dma_start(drive);
#endif
	/* Send the actual packet */
	HWIF(drive)->atapi_output_bytes(drive, pc->c, 12);
	return ide_started;
}

static ide_startstop_t idetape_issue_packet_command (ide_drive_t *drive, idetape_pc_t *pc)
{
	ide_hwif_t *hwif = drive->hwif;
	idetape_tape_t *tape = drive->driver_data;
	atapi_bcount_t bcount;
	int dma_ok = 0;

#if IDETAPE_DEBUG_BUGS
	if (tape->pc->c[0] == IDETAPE_REQUEST_SENSE_CMD &&
	    pc->c[0] == IDETAPE_REQUEST_SENSE_CMD) {
		printk(KERN_ERR "ide-tape: possible ide-tape.c bug - "
			"Two request sense in serial were issued\n");
	}
#endif /* IDETAPE_DEBUG_BUGS */

	if (tape->failed_pc == NULL && pc->c[0] != IDETAPE_REQUEST_SENSE_CMD)
		tape->failed_pc = pc;
	/* Set the current packet command */
	tape->pc = pc;

	if (pc->retries > IDETAPE_MAX_PC_RETRIES ||
	    test_bit(PC_ABORT, &pc->flags)) {
		/*
		 *	We will "abort" retrying a packet command in case
		 *	a legitimate error code was received (crossing a
		 *	filemark, or end of the media, for example).
		 */
		if (!test_bit(PC_ABORT, &pc->flags)) {
			if (!(pc->c[0] == IDETAPE_TEST_UNIT_READY_CMD &&
			      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 = IDETAPE_ERROR_GENERAL;
		}
		tape->failed_pc = NULL;
		return pc->callback(drive);
	}
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 2)
		printk(KERN_INFO "ide-tape: Retry number - %d, cmd = %02X\n", pc->retries, pc->c[0]);
#endif /* IDETAPE_DEBUG_LOG */

	pc->retries++;
	/* We haven't transferred any data yet */
	pc->actually_transferred = 0;
	pc->current_position = pc->buffer;
	/* Request to transfer the entire buffer at once */
	bcount.all = pc->request_transfer;

	if (test_and_clear_bit(PC_DMA_ERROR, &pc->flags)) {
		printk(KERN_WARNING "ide-tape: DMA disabled, "
				"reverting to PIO\n");
		(void)__ide_dma_off(drive);
	}
	if (test_bit(PC_DMA_RECOMMENDED, &pc->flags) && drive->using_dma)
		dma_ok = !hwif->dma_setup(drive);

	if (IDE_CONTROL_REG)
		hwif->OUTB(drive->ctl, IDE_CONTROL_REG);
	hwif->OUTB(dma_ok ? 1 : 0, IDE_FEATURE_REG);	/* Use PIO/DMA */
	hwif->OUTB(bcount.b.high, IDE_BCOUNTH_REG);
	hwif->OUTB(bcount.b.low, IDE_BCOUNTL_REG);
	hwif->OUTB(drive->select.all, IDE_SELECT_REG);
	if (dma_ok)			/* Will begin DMA later */
		set_bit(PC_DMA_IN_PROGRESS, &pc->flags);
	if (test_bit(IDETAPE_DRQ_INTERRUPT, &tape->flags)) {
		ide_set_handler(drive, &idetape_transfer_pc, IDETAPE_WAIT_CMD, NULL);
		hwif->OUTB(WIN_PACKETCMD, IDE_COMMAND_REG);
		return ide_started;
	} else {
		hwif->OUTB(WIN_PACKETCMD, IDE_COMMAND_REG);
		return idetape_transfer_pc(drive);
	}
}

/*
 *	General packet command callback function.
 */
static ide_startstop_t idetape_pc_callback (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_pc_callback\n");
#endif /* IDETAPE_DEBUG_LOG */

	idetape_end_request(drive, tape->pc->error ? 0 : 1, 0);
	return ide_stopped;
}

/*
 *	A mode sense command is used to "sense" tape parameters.
 */
static void idetape_create_mode_sense_cmd (idetape_pc_t *pc, u8 page_code)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_MODE_SENSE_CMD;
	if (page_code != IDETAPE_BLOCK_DESCRIPTOR)
		pc->c[1] = 8;	/* DBD = 1 - Don't return block descriptors */
	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;
	pc->c[4] = 255;		/* (We will just discard data in that case) */
	if (page_code == IDETAPE_BLOCK_DESCRIPTOR)
		pc->request_transfer = 12;
	else if (page_code == IDETAPE_CAPABILITIES_PAGE)
		pc->request_transfer = 24;
	else
		pc->request_transfer = 50;
	pc->callback = &idetape_pc_callback;
}

static void calculate_speeds(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	int full = 125, empty = 75;

	if (time_after(jiffies, tape->controlled_pipeline_head_time + 120 * HZ)) {
		tape->controlled_previous_pipeline_head = tape->controlled_last_pipeline_head;
		tape->controlled_previous_head_time = tape->controlled_pipeline_head_time;
		tape->controlled_last_pipeline_head = tape->pipeline_head;
		tape->controlled_pipeline_head_time = jiffies;
	}
	if (time_after(jiffies, tape->controlled_pipeline_head_time + 60 * HZ))
		tape->controlled_pipeline_head_speed = (tape->pipeline_head - tape->controlled_last_pipeline_head) * 32 * HZ / (jiffies - tape->controlled_pipeline_head_time);
	else if (time_after(jiffies, tape->controlled_previous_head_time))
		tape->controlled_pipeline_head_speed = (tape->pipeline_head - tape->controlled_previous_pipeline_head) * 32 * HZ / (jiffies - tape->controlled_previous_head_time);

	if (tape->nr_pending_stages < tape->max_stages /*- 1 */) {
		/* -1 for read mode error recovery */
		if (time_after(jiffies, tape->uncontrolled_previous_head_time + 10 * HZ)) {
			tape->uncontrolled_pipeline_head_time = jiffies;
			tape->uncontrolled_pipeline_head_speed = (tape->pipeline_head - tape->uncontrolled_previous_pipeline_head) * 32 * HZ / (jiffies - tape->uncontrolled_previous_head_time);
		}
	} else {
		tape->uncontrolled_previous_head_time = jiffies;
		tape->uncontrolled_previous_pipeline_head = tape->pipeline_head;
		if (time_after(jiffies, tape->uncontrolled_pipeline_head_time + 30 * HZ)) {
			tape->uncontrolled_pipeline_head_time = jiffies;
		}
	}
	tape->pipeline_head_speed = max(tape->uncontrolled_pipeline_head_speed, tape->controlled_pipeline_head_speed);
	if (tape->speed_control == 0) {
		tape->max_insert_speed = 5000;
	} else if (tape->speed_control == 1) {
		if (tape->nr_pending_stages >= tape->max_stages / 2)
			tape->max_insert_speed = tape->pipeline_head_speed +
				(1100 - tape->pipeline_head_speed) * 2 * (tape->nr_pending_stages - tape->max_stages / 2) / tape->max_stages;
		else
			tape->max_insert_speed = 500 +
				(tape->pipeline_head_speed - 500) * 2 * tape->nr_pending_stages / tape->max_stages;
		if (tape->nr_pending_stages >= tape->max_stages * 99 / 100)
			tape->max_insert_speed = 5000;
	} else if (tape->speed_control == 2) {
		tape->max_insert_speed = tape->pipeline_head_speed * empty / 100 +
			(tape->pipeline_head_speed * full / 100 - tape->pipeline_head_speed * empty / 100) * tape->nr_pending_stages / tape->max_stages;
	} else
		tape->max_insert_speed = tape->speed_control;
	tape->max_insert_speed = max(tape->max_insert_speed, 500);
}

static ide_startstop_t idetape_media_access_finished (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t *pc = tape->pc;
	atapi_status_t status;

	status.all = HWIF(drive)->INB(IDE_STATUS_REG);
	if (status.b.dsc) {
		if (status.b.check) {
			/* Error detected */
			if (pc->c[0] != IDETAPE_TEST_UNIT_READY_CMD)
				printk(KERN_ERR "ide-tape: %s: I/O error, ",
						tape->name);
			/* Retry operation */
			return idetape_retry_pc(drive);
		}
		pc->error = 0;
		if (tape->failed_pc == pc)
			tape->failed_pc = NULL;
	} else {
		pc->error = IDETAPE_ERROR_GENERAL;
		tape->failed_pc = NULL;
	}
	return pc->callback(drive);
}

static ide_startstop_t idetape_rw_callback (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	struct request *rq = HWGROUP(drive)->rq;
	int blocks = tape->pc->actually_transferred / tape->tape_block_size;

	tape->avg_size += blocks * tape->tape_block_size;
	tape->insert_size += blocks * tape->tape_block_size;
	if (tape->insert_size > 1024 * 1024)
		tape->measure_insert_time = 1;
	if (tape->measure_insert_time) {
		tape->measure_insert_time = 0;
		tape->insert_time = jiffies;
		tape->insert_size = 0;
	}
	if (time_after(jiffies, tape->insert_time))
		tape->insert_speed = tape->insert_size / 1024 * HZ / (jiffies - tape->insert_time);
2338
	if (time_after_eq(jiffies, tape->avg_time + HZ)) {
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		tape->avg_speed = tape->avg_size * HZ / (jiffies - tape->avg_time) / 1024;
		tape->avg_size = 0;
		tape->avg_time = jiffies;
	}

#if IDETAPE_DEBUG_LOG	
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_rw_callback\n");
#endif /* IDETAPE_DEBUG_LOG */

	tape->first_frame_position += blocks;
	rq->current_nr_sectors -= blocks;

	if (!tape->pc->error)
		idetape_end_request(drive, 1, 0);
	else
		idetape_end_request(drive, tape->pc->error, 0);
	return ide_stopped;
}

static void idetape_create_read_cmd(idetape_tape_t *tape, idetape_pc_t *pc, unsigned int length, struct idetape_bh *bh)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_READ_CMD;
	put_unaligned(htonl(length), (unsigned int *) &pc->c[1]);
	pc->c[1] = 1;
	pc->callback = &idetape_rw_callback;
	pc->bh = bh;
	atomic_set(&bh->b_count, 0);
	pc->buffer = NULL;
	pc->request_transfer = pc->buffer_size = length * tape->tape_block_size;
	if (pc->request_transfer == tape->stage_size)
		set_bit(PC_DMA_RECOMMENDED, &pc->flags);
}

static void idetape_create_read_buffer_cmd(idetape_tape_t *tape, idetape_pc_t *pc, unsigned int length, struct idetape_bh *bh)
{
	int size = 32768;
	struct idetape_bh *p = bh;

	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_READ_BUFFER_CMD;
	pc->c[1] = IDETAPE_RETRIEVE_FAULTY_BLOCK;
	pc->c[7] = size >> 8;
	pc->c[8] = size & 0xff;
	pc->callback = &idetape_pc_callback;
	pc->bh = bh;
	atomic_set(&bh->b_count, 0);
	pc->buffer = NULL;
	while (p) {
		atomic_set(&p->b_count, 0);
		p = p->b_reqnext;
	}
	pc->request_transfer = pc->buffer_size = size;
}

static void idetape_create_write_cmd(idetape_tape_t *tape, idetape_pc_t *pc, unsigned int length, struct idetape_bh *bh)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_WRITE_CMD;
	put_unaligned(htonl(length), (unsigned int *) &pc->c[1]);
	pc->c[1] = 1;
	pc->callback = &idetape_rw_callback;
	set_bit(PC_WRITING, &pc->flags);
	pc->bh = bh;
	pc->b_data = bh->b_data;
	pc->b_count = atomic_read(&bh->b_count);
	pc->buffer = NULL;
	pc->request_transfer = pc->buffer_size = length * tape->tape_block_size;
	if (pc->request_transfer == tape->stage_size)
		set_bit(PC_DMA_RECOMMENDED, &pc->flags);
}

/*
 * idetape_do_request is our request handling function.	
 */
static ide_startstop_t idetape_do_request(ide_drive_t *drive,
					  struct request *rq, sector_t block)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t *pc = NULL;
	struct request *postponed_rq = tape->postponed_rq;
	atapi_status_t status;

#if IDETAPE_DEBUG_LOG
#if 0
	if (tape->debug_level >= 5)
2426 2427
		printk(KERN_INFO "ide-tape:  %d, "
			"dev: %s, cmd: %ld, errors: %d\n",
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			 rq->rq_disk->disk_name, rq->cmd[0], rq->errors);
#endif
	if (tape->debug_level >= 2)
		printk(KERN_INFO "ide-tape: sector: %ld, "
			"nr_sectors: %ld, current_nr_sectors: %d\n",
			rq->sector, rq->nr_sectors, rq->current_nr_sectors);
#endif /* IDETAPE_DEBUG_LOG */

2436
	if (!blk_special_request(rq)) {
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		/*
		 * We do not support buffer cache originated requests.
		 */
		printk(KERN_NOTICE "ide-tape: %s: Unsupported request in "
2441
			"request queue (%d)\n", drive->name, rq->cmd_type);
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		ide_end_request(drive, 0, 0);
		return ide_stopped;
	}

	/*
	 *	Retry a failed packet command
	 */
	if (tape->failed_pc != NULL &&
	    tape->pc->c[0] == IDETAPE_REQUEST_SENSE_CMD) {
		return idetape_issue_packet_command(drive, tape->failed_pc);
	}
#if IDETAPE_DEBUG_BUGS
	if (postponed_rq != NULL)
		if (rq != postponed_rq) {
			printk(KERN_ERR "ide-tape: ide-tape.c bug - "
					"Two DSC requests were queued\n");
			idetape_end_request(drive, 0, 0);
			return ide_stopped;
		}
#endif /* IDETAPE_DEBUG_BUGS */

	tape->postponed_rq = NULL;

	/*
	 * If the tape is still busy, postpone our request and service
	 * the other device meanwhile.
	 */
	status.all = HWIF(drive)->INB(IDE_STATUS_REG);

	if (!drive->dsc_overlap && !(rq->cmd[0] & REQ_IDETAPE_PC2))
		set_bit(IDETAPE_IGNORE_DSC, &tape->flags);

	if (drive->post_reset == 1) {
		set_bit(IDETAPE_IGNORE_DSC, &tape->flags);
		drive->post_reset = 0;
	}

	if (tape->tape_still_time > 100 && tape->tape_still_time < 200)
		tape->measure_insert_time = 1;
	if (time_after(jiffies, tape->insert_time))
		tape->insert_speed = tape->insert_size / 1024 * HZ / (jiffies - tape->insert_time);
	calculate_speeds(drive);
	if (!test_and_clear_bit(IDETAPE_IGNORE_DSC, &tape->flags) &&
	    !status.b.dsc) {
		if (postponed_rq == NULL) {
			tape->dsc_polling_start = jiffies;
			tape->dsc_polling_frequency = tape->best_dsc_rw_frequency;
			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 (rq->cmd[0] & REQ_IDETAPE_PC2) {
				idetape_media_access_finished(drive);
				return ide_stopped;
			} else {
				return ide_do_reset(drive);
			}
2499
		} else if (time_after(jiffies, tape->dsc_polling_start + IDETAPE_DSC_MA_THRESHOLD))
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			tape->dsc_polling_frequency = IDETAPE_DSC_MA_SLOW;
		idetape_postpone_request(drive);
		return ide_stopped;
	}
	if (rq->cmd[0] & REQ_IDETAPE_READ) {
		tape->buffer_head++;
#if USE_IOTRACE
		IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
		tape->postpone_cnt = 0;
		pc = idetape_next_pc_storage(drive);
		idetape_create_read_cmd(tape, pc, rq->current_nr_sectors, (struct idetape_bh *)rq->special);
		goto out;
	}
	if (rq->cmd[0] & REQ_IDETAPE_WRITE) {
		tape->buffer_head++;
#if USE_IOTRACE
		IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
		tape->postpone_cnt = 0;
		pc = idetape_next_pc_storage(drive);
		idetape_create_write_cmd(tape, pc, rq->current_nr_sectors, (struct idetape_bh *)rq->special);
		goto out;
	}
	if (rq->cmd[0] & REQ_IDETAPE_READ_BUFFER) {
		tape->postpone_cnt = 0;
		pc = idetape_next_pc_storage(drive);
		idetape_create_read_buffer_cmd(tape, pc, rq->current_nr_sectors, (struct idetape_bh *)rq->special);
		goto out;
	}
	if (rq->cmd[0] & REQ_IDETAPE_PC1) {
		pc = (idetape_pc_t *) rq->buffer;
		rq->cmd[0] &= ~(REQ_IDETAPE_PC1);
		rq->cmd[0] |= REQ_IDETAPE_PC2;
		goto out;
	}
	if (rq->cmd[0] & REQ_IDETAPE_PC2) {
		idetape_media_access_finished(drive);
		return ide_stopped;
	}
	BUG();
out:
	return idetape_issue_packet_command(drive, pc);
}

/*
 *	Pipeline related functions
 */
static inline int idetape_pipeline_active (idetape_tape_t *tape)
{
	int rc1, rc2;

	rc1 = test_bit(IDETAPE_PIPELINE_ACTIVE, &tape->flags);
	rc2 = (tape->active_data_request != NULL);
	return rc1;
}

/*
 *	idetape_kmalloc_stage uses __get_free_page to allocate a pipeline
 *	stage, along with all the necessary small buffers which together make
 *	a buffer of size tape->stage_size (or a bit more). We attempt to
 *	combine sequential pages as much as possible.
 *
 *	Returns a pointer to the new allocated stage, or NULL if we
 *	can't (or don't want to) allocate a stage.
 *
 *	Pipeline stages are optional and are used to increase performance.
 *	If we can't allocate them, we'll manage without them.
 */
static idetape_stage_t *__idetape_kmalloc_stage (idetape_tape_t *tape, int full, int clear)
{
	idetape_stage_t *stage;
	struct idetape_bh *prev_bh, *bh;
	int pages = tape->pages_per_stage;
	char *b_data = NULL;

	if ((stage = (idetape_stage_t *) kmalloc (sizeof (idetape_stage_t),GFP_KERNEL)) == NULL)
		return NULL;
	stage->next = NULL;

	bh = stage->bh = (struct idetape_bh *)kmalloc(sizeof(struct idetape_bh), GFP_KERNEL);
	if (bh == NULL)
		goto abort;
	bh->b_reqnext = NULL;
	if ((bh->b_data = (char *) __get_free_page (GFP_KERNEL)) == NULL)
		goto abort;
	if (clear)
		memset(bh->b_data, 0, PAGE_SIZE);
	bh->b_size = PAGE_SIZE;
	atomic_set(&bh->b_count, full ? bh->b_size : 0);

	while (--pages) {
		if ((b_data = (char *) __get_free_page (GFP_KERNEL)) == NULL)
			goto abort;
		if (clear)
			memset(b_data, 0, PAGE_SIZE);
		if (bh->b_data == b_data + PAGE_SIZE) {
			bh->b_size += PAGE_SIZE;
			bh->b_data -= PAGE_SIZE;
			if (full)
				atomic_add(PAGE_SIZE, &bh->b_count);
			continue;
		}
		if (b_data == bh->b_data + bh->b_size) {
			bh->b_size += PAGE_SIZE;
			if (full)
				atomic_add(PAGE_SIZE, &bh->b_count);
			continue;
		}
		prev_bh = bh;
		if ((bh = (struct idetape_bh *)kmalloc(sizeof(struct idetape_bh), GFP_KERNEL)) == NULL) {
			free_page((unsigned long) b_data);
			goto abort;
		}
		bh->b_reqnext = NULL;
		bh->b_data = b_data;
		bh->b_size = PAGE_SIZE;
		atomic_set(&bh->b_count, full ? bh->b_size : 0);
		prev_bh->b_reqnext = bh;
	}
	bh->b_size -= tape->excess_bh_size;
	if (full)
		atomic_sub(tape->excess_bh_size, &bh->b_count);
	return stage;
abort:
	__idetape_kfree_stage(stage);
	return NULL;
}

static idetape_stage_t *idetape_kmalloc_stage (idetape_tape_t *tape)
{
	idetape_stage_t *cache_stage = tape->cache_stage;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_kmalloc_stage\n");
#endif /* IDETAPE_DEBUG_LOG */

	if (tape->nr_stages >= tape->max_stages)
		return NULL;
	if (cache_stage != NULL) {
		tape->cache_stage = NULL;
		return cache_stage;
	}
	return __idetape_kmalloc_stage(tape, 0, 0);
}

2647
static int idetape_copy_stage_from_user (idetape_tape_t *tape, idetape_stage_t *stage, const char __user *buf, int n)
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{
	struct idetape_bh *bh = tape->bh;
	int count;
2651
	int ret = 0;
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	while (n) {
#if IDETAPE_DEBUG_BUGS
		if (bh == NULL) {
			printk(KERN_ERR "ide-tape: bh == NULL in "
				"idetape_copy_stage_from_user\n");
2658
			return 1;
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		}
#endif /* IDETAPE_DEBUG_BUGS */
		count = min((unsigned int)(bh->b_size - atomic_read(&bh->b_count)), (unsigned int)n);
2662 2663
		if (copy_from_user(bh->b_data + atomic_read(&bh->b_count), buf, count))
			ret = 1;
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		n -= count;
		atomic_add(count, &bh->b_count);
		buf += count;
		if (atomic_read(&bh->b_count) == bh->b_size) {
			bh = bh->b_reqnext;
			if (bh)
				atomic_set(&bh->b_count, 0);
		}
	}
	tape->bh = bh;
2674
	return ret;
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}

2677
static int idetape_copy_stage_to_user (idetape_tape_t *tape, char __user *buf, idetape_stage_t *stage, int n)
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{
	struct idetape_bh *bh = tape->bh;
	int count;
2681
	int ret = 0;
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	while (n) {
#if IDETAPE_DEBUG_BUGS
		if (bh == NULL) {
			printk(KERN_ERR "ide-tape: bh == NULL in "
				"idetape_copy_stage_to_user\n");
2688
			return 1;
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		}
#endif /* IDETAPE_DEBUG_BUGS */
		count = min(tape->b_count, n);
2692 2693
		if  (copy_to_user(buf, tape->b_data, count))
			ret = 1;
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		n -= count;
		tape->b_data += count;
		tape->b_count -= count;
		buf += count;
		if (!tape->b_count) {
			tape->bh = bh = bh->b_reqnext;
			if (bh) {
				tape->b_data = bh->b_data;
				tape->b_count = atomic_read(&bh->b_count);
			}
		}
	}
2706
	return ret;
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}

static void idetape_init_merge_stage (idetape_tape_t *tape)
{
	struct idetape_bh *bh = tape->merge_stage->bh;
	
	tape->bh = bh;
	if (tape->chrdev_direction == idetape_direction_write)
		atomic_set(&bh->b_count, 0);
	else {
		tape->b_data = bh->b_data;
		tape->b_count = atomic_read(&bh->b_count);
	}
}

static void idetape_switch_buffers (idetape_tape_t *tape, idetape_stage_t *stage)
{
	struct idetape_bh *tmp;

	tmp = stage->bh;
	stage->bh = tape->merge_stage->bh;
	tape->merge_stage->bh = tmp;
	idetape_init_merge_stage(tape);
}

/*
 *	idetape_add_stage_tail adds a new stage at the end of the pipeline.
 */
static void idetape_add_stage_tail (ide_drive_t *drive,idetape_stage_t *stage)
{
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;
	
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk (KERN_INFO "ide-tape: Reached idetape_add_stage_tail\n");
#endif /* IDETAPE_DEBUG_LOG */
	spin_lock_irqsave(&tape->spinlock, flags);
	stage->next = NULL;
	if (tape->last_stage != NULL)
		tape->last_stage->next=stage;
	else
		tape->first_stage = tape->next_stage=stage;
	tape->last_stage = stage;
	if (tape->next_stage == NULL)
		tape->next_stage = tape->last_stage;
	tape->nr_stages++;
	tape->nr_pending_stages++;
	spin_unlock_irqrestore(&tape->spinlock, flags);
}

/*
 *	idetape_wait_for_request installs a completion in a pending request
 *	and sleeps until it is serviced.
 *
 *	The caller should ensure that the request will not be serviced
 *	before we install the completion (usually by disabling interrupts).
 */
static void idetape_wait_for_request (ide_drive_t *drive, struct request *rq)
{
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	DECLARE_COMPLETION_ONSTACK(wait);
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	idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_BUGS
2771
	if (rq == NULL || !blk_special_request(rq)) {
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		printk (KERN_ERR "ide-tape: bug: Trying to sleep on non-valid request\n");
		return;
	}
#endif /* IDETAPE_DEBUG_BUGS */
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	rq->end_io_data = &wait;
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	rq->end_io = blk_end_sync_rq;
	spin_unlock_irq(&tape->spinlock);
	wait_for_completion(&wait);
	/* The stage and its struct request have been deallocated */
	spin_lock_irq(&tape->spinlock);
}

static ide_startstop_t idetape_read_position_callback (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_read_position_result_t *result;
	
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_read_position_callback\n");
#endif /* IDETAPE_DEBUG_LOG */

	if (!tape->pc->error) {
		result = (idetape_read_position_result_t *) tape->pc->buffer;
#if IDETAPE_DEBUG_LOG
		if (tape->debug_level >= 2)
			printk(KERN_INFO "ide-tape: BOP - %s\n",result->bop ? "Yes":"No");
		if (tape->debug_level >= 2)
			printk(KERN_INFO "ide-tape: EOP - %s\n",result->eop ? "Yes":"No");
#endif /* IDETAPE_DEBUG_LOG */
		if (result->bpu) {
			printk(KERN_INFO "ide-tape: Block location is unknown to the tape\n");
			clear_bit(IDETAPE_ADDRESS_VALID, &tape->flags);
			idetape_end_request(drive, 0, 0);
		} else {
#if IDETAPE_DEBUG_LOG
			if (tape->debug_level >= 2)
				printk(KERN_INFO "ide-tape: Block Location - %u\n", ntohl(result->first_block));
#endif /* IDETAPE_DEBUG_LOG */
			tape->partition = result->partition;
			tape->first_frame_position = ntohl(result->first_block);
			tape->last_frame_position = ntohl(result->last_block);
			tape->blocks_in_buffer = result->blocks_in_buffer[2];
			set_bit(IDETAPE_ADDRESS_VALID, &tape->flags);
			idetape_end_request(drive, 1, 0);
		}
	} else {
		idetape_end_request(drive, 0, 0);
	}
	return ide_stopped;
}

/*
 *	idetape_create_write_filemark_cmd will:
 *
 *		1.	Write a filemark if write_filemark=1.
 *		2.	Flush the device buffers without writing a filemark
 *			if write_filemark=0.
 *
 */
static void idetape_create_write_filemark_cmd (ide_drive_t *drive, idetape_pc_t *pc,int write_filemark)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_WRITE_FILEMARK_CMD;
	pc->c[4] = write_filemark;
	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
	pc->callback = &idetape_pc_callback;
}

static void idetape_create_test_unit_ready_cmd(idetape_pc_t *pc)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_TEST_UNIT_READY_CMD;
	pc->callback = &idetape_pc_callback;
}

/*
 *	idetape_queue_pc_tail is based on the following functions:
 *
 *	ide_do_drive_cmd from ide.c
 *	cdrom_queue_request and cdrom_queue_packet_command from ide-cd.c
 *
 *	We add a special packet command request to the tail of the request
 *	queue, and wait for it to be serviced.
 *
 *	This is not to be called from within the request handling part
 *	of the driver ! We allocate here data in the stack, and it is valid
 *	until the request is finished. This is not the case for the bottom
 *	part of the driver, where we are always leaving the functions to wait
 *	for an interrupt or a timer event.
 *
 *	From the bottom part of the driver, we should allocate safe memory
 *	using idetape_next_pc_storage and idetape_next_rq_storage, and add
 *	the request to the request list without waiting for it to be serviced !
 *	In that case, we usually use idetape_queue_pc_head.
 */
static int __idetape_queue_pc_tail (ide_drive_t *drive, idetape_pc_t *pc)
{
	struct ide_tape_obj *tape = drive->driver_data;
	struct request rq;

	idetape_init_rq(&rq, REQ_IDETAPE_PC1);
	rq.buffer = (char *) pc;
	rq.rq_disk = tape->disk;
	return ide_do_drive_cmd(drive, &rq, ide_wait);
}

static void idetape_create_load_unload_cmd (ide_drive_t *drive, idetape_pc_t *pc,int cmd)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_LOAD_UNLOAD_CMD;
	pc->c[4] = cmd;
	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
	pc->callback = &idetape_pc_callback;
}

static int idetape_wait_ready(ide_drive_t *drive, unsigned long timeout)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t pc;
	int load_attempted = 0;

	/*
	 * Wait for the tape to become ready
	 */
	set_bit(IDETAPE_MEDIUM_PRESENT, &tape->flags);
	timeout += jiffies;
	while (time_before(jiffies, timeout)) {
		idetape_create_test_unit_ready_cmd(&pc);
		if (!__idetape_queue_pc_tail(drive, &pc))
			return 0;
		if ((tape->sense_key == 2 && tape->asc == 4 && tape->ascq == 2)
		    || (tape->asc == 0x3A)) {	/* no media */
			if (load_attempted)
				return -ENOMEDIUM;
			idetape_create_load_unload_cmd(drive, &pc, IDETAPE_LU_LOAD_MASK);
			__idetape_queue_pc_tail(drive, &pc);
			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;
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	}
	return -EIO;
}

static int idetape_queue_pc_tail (ide_drive_t *drive,idetape_pc_t *pc)
{
	return __idetape_queue_pc_tail(drive, pc);
}

static int idetape_flush_tape_buffers (ide_drive_t *drive)
{
	idetape_pc_t pc;
	int rc;

	idetape_create_write_filemark_cmd(drive, &pc, 0);
	if ((rc = idetape_queue_pc_tail(drive, &pc)))
		return rc;
	idetape_wait_ready(drive, 60 * 5 * HZ);
	return 0;
}

static void idetape_create_read_position_cmd (idetape_pc_t *pc)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_READ_POSITION_CMD;
	pc->request_transfer = 20;
	pc->callback = &idetape_read_position_callback;
}

static int idetape_read_position (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t pc;
	int position;

#if IDETAPE_DEBUG_LOG
        if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_read_position\n");
#endif /* IDETAPE_DEBUG_LOG */

	idetape_create_read_position_cmd(&pc);
	if (idetape_queue_pc_tail(drive, &pc))
		return -1;
	position = tape->first_frame_position;
	return position;
}

static void idetape_create_locate_cmd (ide_drive_t *drive, idetape_pc_t *pc, unsigned int block, u8 partition, int skip)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_LOCATE_CMD;
	pc->c[1] = 2;
	put_unaligned(htonl(block), (unsigned int *) &pc->c[3]);
	pc->c[8] = partition;
	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
	pc->callback = &idetape_pc_callback;
}

static int idetape_create_prevent_cmd (ide_drive_t *drive, idetape_pc_t *pc, int prevent)
{
	idetape_tape_t *tape = drive->driver_data;

	if (!tape->capabilities.lock)
		return 0;

	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_PREVENT_CMD;
	pc->c[4] = prevent;
	pc->callback = &idetape_pc_callback;
	return 1;
}

static int __idetape_discard_read_pipeline (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;
	int cnt;

	if (tape->chrdev_direction != idetape_direction_read)
		return 0;

	/* Remove merge stage. */
	cnt = tape->merge_stage_size / tape->tape_block_size;
	if (test_and_clear_bit(IDETAPE_FILEMARK, &tape->flags))
		++cnt;		/* Filemarks count as 1 sector */
	tape->merge_stage_size = 0;
	if (tape->merge_stage != NULL) {
		__idetape_kfree_stage(tape->merge_stage);
		tape->merge_stage = NULL;
	}

	/* Clear pipeline flags. */
	clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
	tape->chrdev_direction = idetape_direction_none;

	/* Remove pipeline stages. */
	if (tape->first_stage == NULL)
		return 0;

	spin_lock_irqsave(&tape->spinlock, flags);
	tape->next_stage = NULL;
	if (idetape_pipeline_active(tape))
		idetape_wait_for_request(drive, tape->active_data_request);
	spin_unlock_irqrestore(&tape->spinlock, flags);

	while (tape->first_stage != NULL) {
		struct request *rq_ptr = &tape->first_stage->rq;

		cnt += rq_ptr->nr_sectors - rq_ptr->current_nr_sectors; 
		if (rq_ptr->errors == IDETAPE_ERROR_FILEMARK)
			++cnt;
		idetape_remove_stage_head(drive);
	}
	tape->nr_pending_stages = 0;
	tape->max_stages = tape->min_pipeline;
	return cnt;
}

/*
 *	idetape_position_tape positions 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;
	int retval;
	idetape_pc_t pc;

	if (tape->chrdev_direction == idetape_direction_read)
		__idetape_discard_read_pipeline(drive);
	idetape_wait_ready(drive, 60 * 5 * HZ);
	idetape_create_locate_cmd(drive, &pc, block, partition, skip);
	retval = idetape_queue_pc_tail(drive, &pc);
	if (retval)
		return (retval);

	idetape_create_read_position_cmd(&pc);
	return (idetape_queue_pc_tail(drive, &pc));
}

static void idetape_discard_read_pipeline (ide_drive_t *drive, int restore_position)
{
	idetape_tape_t *tape = drive->driver_data;
	int cnt;
	int seek, position;

	cnt = __idetape_discard_read_pipeline(drive);
	if (restore_position) {
		position = idetape_read_position(drive);
		seek = position > cnt ? position - cnt : 0;
		if (idetape_position_tape(drive, seek, 0, 0)) {
			printk(KERN_INFO "ide-tape: %s: position_tape failed in discard_pipeline()\n", tape->name);
			return;
		}
	}
}

/*
 * idetape_queue_rw_tail generates 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 blocks, struct idetape_bh *bh)
{
	idetape_tape_t *tape = drive->driver_data;
	struct request rq;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 2)
		printk(KERN_INFO "ide-tape: idetape_queue_rw_tail: cmd=%d\n",cmd);
#endif /* IDETAPE_DEBUG_LOG */
#if IDETAPE_DEBUG_BUGS
	if (idetape_pipeline_active(tape)) {
		printk(KERN_ERR "ide-tape: bug: the pipeline is active in idetape_queue_rw_tail\n");
		return (0);
	}
#endif /* IDETAPE_DEBUG_BUGS */	

	idetape_init_rq(&rq, cmd);
	rq.rq_disk = tape->disk;
	rq.special = (void *)bh;
	rq.sector = tape->first_frame_position;
	rq.nr_sectors = rq.current_nr_sectors = blocks;
	(void) ide_do_drive_cmd(drive, &rq, ide_wait);

	if ((cmd & (REQ_IDETAPE_READ | REQ_IDETAPE_WRITE)) == 0)
		return 0;

	if (tape->merge_stage)
		idetape_init_merge_stage(tape);
	if (rq.errors == IDETAPE_ERROR_GENERAL)
		return -EIO;
	return (tape->tape_block_size * (blocks-rq.current_nr_sectors));
}

/*
 *	idetape_insert_pipeline_into_queue is used to start servicing the
 *	pipeline stages, starting from tape->next_stage.
 */
static void idetape_insert_pipeline_into_queue (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

	if (tape->next_stage == NULL)
		return;
	if (!idetape_pipeline_active(tape)) {
		set_bit(IDETAPE_PIPELINE_ACTIVE, &tape->flags);
		idetape_active_next_stage(drive);
		(void) ide_do_drive_cmd(drive, tape->active_data_request, ide_end);
	}
}

static void idetape_create_inquiry_cmd (idetape_pc_t *pc)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_INQUIRY_CMD;
	pc->c[4] = pc->request_transfer = 254;
	pc->callback = &idetape_pc_callback;
}

static void idetape_create_rewind_cmd (ide_drive_t *drive, idetape_pc_t *pc)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_REWIND_CMD;
	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
	pc->callback = &idetape_pc_callback;
}

#if 0
static void idetape_create_mode_select_cmd (idetape_pc_t *pc, int length)
{
	idetape_init_pc(pc);
	set_bit(PC_WRITING, &pc->flags);
	pc->c[0] = IDETAPE_MODE_SELECT_CMD;
	pc->c[1] = 0x10;
	put_unaligned(htons(length), (unsigned short *) &pc->c[3]);
	pc->request_transfer = 255;
	pc->callback = &idetape_pc_callback;
}
#endif

static void idetape_create_erase_cmd (idetape_pc_t *pc)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_ERASE_CMD;
	pc->c[1] = 1;
	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
	pc->callback = &idetape_pc_callback;
}

static void idetape_create_space_cmd (idetape_pc_t *pc,int count, u8 cmd)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_SPACE_CMD;
	put_unaligned(htonl(count), (unsigned int *) &pc->c[1]);
	pc->c[1] = cmd;
	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
	pc->callback = &idetape_pc_callback;
}

static void idetape_wait_first_stage (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;

	if (tape->first_stage == NULL)
		return;
	spin_lock_irqsave(&tape->spinlock, flags);
	if (tape->active_stage == tape->first_stage)
		idetape_wait_for_request(drive, tape->active_data_request);
	spin_unlock_irqrestore(&tape->spinlock, flags);
}

/*
 *	idetape_add_chrdev_write_request tries to add a character device
 *	originated write request to our pipeline. In case we don't succeed,
 *	we revert to non-pipelined operation mode for this request.
 *
 *	1.	Try to allocate a new pipeline stage.
 *	2.	If we can't, wait for more and more requests to be serviced
 *		and try again each time.
 *	3.	If we still can't allocate a stage, fallback to
 *		non-pipelined operation mode for this request.
 */
static int idetape_add_chrdev_write_request (ide_drive_t *drive, int blocks)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *new_stage;
	unsigned long flags;
	struct request *rq;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 3)
		printk(KERN_INFO "ide-tape: Reached idetape_add_chrdev_write_request\n");
#endif /* IDETAPE_DEBUG_LOG */

     	/*
     	 *	Attempt to allocate a new stage.
	 *	Pay special attention to possible race conditions.
	 */
	while ((new_stage = idetape_kmalloc_stage(tape)) == NULL) {
		spin_lock_irqsave(&tape->spinlock, flags);
		if (idetape_pipeline_active(tape)) {
			idetape_wait_for_request(drive, tape->active_data_request);
			spin_unlock_irqrestore(&tape->spinlock, flags);
		} else {
			spin_unlock_irqrestore(&tape->spinlock, flags);
			idetape_insert_pipeline_into_queue(drive);
			if (idetape_pipeline_active(tape))
				continue;
			/*
			 *	Linux is short on memory. Fallback to
			 *	non-pipelined operation mode for this request.
			 */
			return idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, blocks, tape->merge_stage->bh);
		}
	}
	rq = &new_stage->rq;
	idetape_init_rq(rq, REQ_IDETAPE_WRITE);
	/* Doesn't actually matter - We always assume sequential access */
	rq->sector = tape->first_frame_position;
	rq->nr_sectors = rq->current_nr_sectors = blocks;

	idetape_switch_buffers(tape, new_stage);
	idetape_add_stage_tail(drive, new_stage);
	tape->pipeline_head++;
#if USE_IOTRACE
	IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
	calculate_speeds(drive);

	/*
	 *	Estimate whether the tape has stopped writing by checking
	 *	if our write pipeline is currently empty. If we are not
	 *	writing anymore, wait for the pipeline to be full enough
	 *	(90%) before starting to service requests, so that we will
	 *	be able to keep up with the higher speeds of the tape.
	 */
	if (!idetape_pipeline_active(tape)) {
		if (tape->nr_stages >= tape->max_stages * 9 / 10 ||
		    tape->nr_stages >= tape->max_stages - tape->uncontrolled_pipeline_head_speed * 3 * 1024 / tape->tape_block_size) {
			tape->measure_insert_time = 1;
			tape->insert_time = jiffies;
			tape->insert_size = 0;
			tape->insert_speed = 0;
			idetape_insert_pipeline_into_queue(drive);
		}
	}
	if (test_and_clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags))
		/* Return a deferred error */
		return -EIO;
	return blocks;
}

/*
 *	idetape_wait_for_pipeline will wait until all pending pipeline
 *	requests are serviced. Typically called on device close.
 */
static void idetape_wait_for_pipeline (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;

	while (tape->next_stage || idetape_pipeline_active(tape)) {
		idetape_insert_pipeline_into_queue(drive);
		spin_lock_irqsave(&tape->spinlock, flags);
		if (idetape_pipeline_active(tape))
			idetape_wait_for_request(drive, tape->active_data_request);
		spin_unlock_irqrestore(&tape->spinlock, flags);
	}
}

static void idetape_empty_write_pipeline (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	int blocks, min;
	struct idetape_bh *bh;
	
#if IDETAPE_DEBUG_BUGS
	if (tape->chrdev_direction != idetape_direction_write) {
		printk(KERN_ERR "ide-tape: bug: Trying to empty write pipeline, but we are not writing.\n");
		return;
	}
	if (tape->merge_stage_size > tape->stage_size) {
		printk(KERN_ERR "ide-tape: bug: merge_buffer too big\n");
		tape->merge_stage_size = tape->stage_size;
	}
#endif /* IDETAPE_DEBUG_BUGS */
	if (tape->merge_stage_size) {
		blocks = tape->merge_stage_size / tape->tape_block_size;
		if (tape->merge_stage_size % tape->tape_block_size) {
			unsigned int i;

			blocks++;
			i = tape->tape_block_size - tape->merge_stage_size % tape->tape_block_size;
			bh = tape->bh->b_reqnext;
			while (bh) {
				atomic_set(&bh->b_count, 0);
				bh = bh->b_reqnext;
			}
			bh = tape->bh;
			while (i) {
				if (bh == NULL) {

					printk(KERN_INFO "ide-tape: bug, bh NULL\n");
					break;
				}
				min = min(i, (unsigned int)(bh->b_size - atomic_read(&bh->b_count)));
				memset(bh->b_data + atomic_read(&bh->b_count), 0, min);
				atomic_add(min, &bh->b_count);
				i -= min;
				bh = bh->b_reqnext;
			}
		}
		(void) idetape_add_chrdev_write_request(drive, blocks);
		tape->merge_stage_size = 0;
	}
	idetape_wait_for_pipeline(drive);
	if (tape->merge_stage != NULL) {
		__idetape_kfree_stage(tape->merge_stage);
		tape->merge_stage = NULL;
	}
	clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
	tape->chrdev_direction = idetape_direction_none;

	/*
	 *	On the next backup, perform the feedback loop again.
	 *	(I don't want to keep sense information between backups,
	 *	 as some systems are constantly on, and the system load
	 *	 can be totally different on the next backup).
	 */
	tape->max_stages = tape->min_pipeline;
#if IDETAPE_DEBUG_BUGS
	if (tape->first_stage != NULL ||
	    tape->next_stage != NULL ||
	    tape->last_stage != NULL ||
	    tape->nr_stages != 0) {
		printk(KERN_ERR "ide-tape: ide-tape pipeline bug, "
			"first_stage %p, next_stage %p, "
			"last_stage %p, nr_stages %d\n",
			tape->first_stage, tape->next_stage,
			tape->last_stage, tape->nr_stages);
	}
#endif /* IDETAPE_DEBUG_BUGS */
}

static void idetape_restart_speed_control (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

	tape->restart_speed_control_req = 0;
	tape->pipeline_head = 0;
	tape->controlled_last_pipeline_head = tape->uncontrolled_last_pipeline_head = 0;
	tape->controlled_previous_pipeline_head = tape->uncontrolled_previous_pipeline_head = 0;
	tape->pipeline_head_speed = tape->controlled_pipeline_head_speed = 5000;
	tape->uncontrolled_pipeline_head_speed = 0;
	tape->controlled_pipeline_head_time = tape->uncontrolled_pipeline_head_time = jiffies;
	tape->controlled_previous_head_time = tape->uncontrolled_previous_head_time = jiffies;
}

static int idetape_initiate_read (ide_drive_t *drive, int max_stages)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *new_stage;
	struct request rq;
	int bytes_read;
	int blocks = tape->capabilities.ctl;

	/* Initialize read operation */
	if (tape->chrdev_direction != idetape_direction_read) {
		if (tape->chrdev_direction == idetape_direction_write) {
			idetape_empty_write_pipeline(drive);
			idetape_flush_tape_buffers(drive);
		}
#if IDETAPE_DEBUG_BUGS
		if (tape->merge_stage || tape->merge_stage_size) {
			printk (KERN_ERR "ide-tape: merge_stage_size should be 0 now\n");
			tape->merge_stage_size = 0;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		if ((tape->merge_stage = __idetape_kmalloc_stage(tape, 0, 0)) == NULL)
			return -ENOMEM;
		tape->chrdev_direction = idetape_direction_read;

		/*
		 *	Issue a read 0 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->dsc_overlap) {
			bytes_read = idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, 0, tape->merge_stage->bh);
			if (bytes_read < 0) {
				__idetape_kfree_stage(tape->merge_stage);
				tape->merge_stage = NULL;
				tape->chrdev_direction = idetape_direction_none;
				return bytes_read;
			}
		}
	}
	if (tape->restart_speed_control_req)
		idetape_restart_speed_control(drive);
	idetape_init_rq(&rq, REQ_IDETAPE_READ);
	rq.sector = tape->first_frame_position;
	rq.nr_sectors = rq.current_nr_sectors = blocks;
	if (!test_bit(IDETAPE_PIPELINE_ERROR, &tape->flags) &&
	    tape->nr_stages < max_stages) {
		new_stage = idetape_kmalloc_stage(tape);
		while (new_stage != NULL) {
			new_stage->rq = rq;
			idetape_add_stage_tail(drive, new_stage);
			if (tape->nr_stages >= max_stages)
				break;
			new_stage = idetape_kmalloc_stage(tape);
		}
	}
	if (!idetape_pipeline_active(tape)) {
		if (tape->nr_pending_stages >= 3 * max_stages / 4) {
			tape->measure_insert_time = 1;
			tape->insert_time = jiffies;
			tape->insert_size = 0;
			tape->insert_speed = 0;
			idetape_insert_pipeline_into_queue(drive);
		}
	}
	return 0;
}

/*
 *	idetape_add_chrdev_read_request is called from idetape_chrdev_read
 *	to service a character device read request and add read-ahead
 *	requests to our pipeline.
 */
static int idetape_add_chrdev_read_request (ide_drive_t *drive,int blocks)
{
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;
	struct request *rq_ptr;
	int bytes_read;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_add_chrdev_read_request, %d blocks\n", blocks);
#endif /* IDETAPE_DEBUG_LOG */

	/*
	 * If we are at a filemark, return a read length of 0
	 */
	if (test_bit(IDETAPE_FILEMARK, &tape->flags))
		return 0;

	/*
	 * Wait for the next block to be available at the head
	 * of the pipeline
	 */
	idetape_initiate_read(drive, tape->max_stages);
	if (tape->first_stage == NULL) {
		if (test_bit(IDETAPE_PIPELINE_ERROR, &tape->flags))
			return 0;
		return idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, blocks, tape->merge_stage->bh);
	}
	idetape_wait_first_stage(drive);
	rq_ptr = &tape->first_stage->rq;
	bytes_read = tape->tape_block_size * (rq_ptr->nr_sectors - rq_ptr->current_nr_sectors);
	rq_ptr->nr_sectors = rq_ptr->current_nr_sectors = 0;


	if (rq_ptr->errors == IDETAPE_ERROR_EOD)
		return 0;
	else {
		idetape_switch_buffers(tape, tape->first_stage);
		if (rq_ptr->errors == IDETAPE_ERROR_FILEMARK)
			set_bit(IDETAPE_FILEMARK, &tape->flags);
		spin_lock_irqsave(&tape->spinlock, flags);
		idetape_remove_stage_head(drive);
		spin_unlock_irqrestore(&tape->spinlock, flags);
		tape->pipeline_head++;
#if USE_IOTRACE
		IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
		calculate_speeds(drive);
	}
#if IDETAPE_DEBUG_BUGS
	if (bytes_read > blocks * tape->tape_block_size) {
		printk(KERN_ERR "ide-tape: bug: trying to return more bytes than requested\n");
		bytes_read = blocks * tape->tape_block_size;
	}
#endif /* IDETAPE_DEBUG_BUGS */
	return (bytes_read);
}

static void idetape_pad_zeros (ide_drive_t *drive, int bcount)
{
	idetape_tape_t *tape = drive->driver_data;
	struct idetape_bh *bh;
	int blocks;
	
	while (bcount) {
		unsigned int count;

		bh = tape->merge_stage->bh;
		count = min(tape->stage_size, bcount);
		bcount -= count;
		blocks = count / tape->tape_block_size;
		while (count) {
			atomic_set(&bh->b_count, min(count, (unsigned int)bh->b_size));
			memset(bh->b_data, 0, atomic_read(&bh->b_count));
			count -= atomic_read(&bh->b_count);
			bh = bh->b_reqnext;
		}
		idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, blocks, tape->merge_stage->bh);
	}
}

static int idetape_pipeline_size (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *stage;
	struct request *rq;
	int size = 0;

	idetape_wait_for_pipeline(drive);
	stage = tape->first_stage;
	while (stage != NULL) {
		rq = &stage->rq;
		size += tape->tape_block_size * (rq->nr_sectors-rq->current_nr_sectors);
		if (rq->errors == IDETAPE_ERROR_FILEMARK)
			size += tape->tape_block_size;
		stage = stage->next;
	}
	size += tape->merge_stage_size;
	return size;
}

/*
 *	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)
{
	int retval;
	idetape_pc_t pc;
#if IDETAPE_DEBUG_LOG
	idetape_tape_t *tape = drive->driver_data;
	if (tape->debug_level >= 2)
		printk(KERN_INFO "ide-tape: Reached idetape_rewind_tape\n");
#endif /* IDETAPE_DEBUG_LOG */	
	
	idetape_create_rewind_cmd(drive, &pc);
	retval = idetape_queue_pc_tail(drive, &pc);
	if (retval)
		return retval;

	idetape_create_read_position_cmd(&pc);
	retval = idetape_queue_pc_tail(drive, &pc);
	if (retval)
		return retval;
	return 0;
}

/*
 *	Our special ide-tape ioctl's.
 *
 *	Currently there aren't any ioctl's.
 *	mtio.h compatible commands should be issued to the character device
 *	interface.
 */
static int idetape_blkdev_ioctl(ide_drive_t *drive, unsigned int cmd, unsigned long arg)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_config_t config;
	void __user *argp = (void __user *)arg;

#if IDETAPE_DEBUG_LOG	
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_blkdev_ioctl\n");
#endif /* IDETAPE_DEBUG_LOG */
	switch (cmd) {
		case 0x0340:
			if (copy_from_user(&config, argp, sizeof (idetape_config_t)))
				return -EFAULT;
			tape->best_dsc_rw_frequency = config.dsc_rw_frequency;
			tape->max_stages = config.nr_stages;
			break;
		case 0x0350:
			config.dsc_rw_frequency = (int) tape->best_dsc_rw_frequency;
			config.nr_stages = tape->max_stages; 
			if (copy_to_user(argp, &config, sizeof (idetape_config_t)))
				return -EFAULT;
			break;
		default:
			return -EIO;
	}
	return 0;
}

/*
 *	idetape_space_over_filemarks is now a bit more complicated than just
 *	passing the command to the tape since we may have crossed some
 *	filemarks during our pipelined read-ahead mode.
 *
 *	As a minor side effect, the pipeline enables us to support MTFSFM when
 *	the filemark is in our internal pipeline even if the tape doesn't
 *	support spacing over filemarks in the reverse direction.
 */
static int idetape_space_over_filemarks (ide_drive_t *drive,short mt_op,int mt_count)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t pc;
	unsigned long flags;
	int retval,count=0;

	if (mt_count == 0)
		return 0;
	if (MTBSF == mt_op || MTBSFM == mt_op) {
		if (!tape->capabilities.sprev)
			return -EIO;
		mt_count = - mt_count;
	}

	if (tape->chrdev_direction == idetape_direction_read) {
		/*
		 *	We have a read-ahead buffer. Scan it for crossed
		 *	filemarks.
		 */
		tape->merge_stage_size = 0;
		if (test_and_clear_bit(IDETAPE_FILEMARK, &tape->flags))
			++count;
		while (tape->first_stage != NULL) {
			if (count == mt_count) {
				if (mt_op == MTFSFM)
					set_bit(IDETAPE_FILEMARK, &tape->flags);
				return 0;
			}
			spin_lock_irqsave(&tape->spinlock, flags);
			if (tape->first_stage == tape->active_stage) {
				/*
				 *	We have reached the active stage in the read pipeline.
				 *	There is no point in allowing the drive to continue
				 *	reading any farther, so we stop the pipeline.
				 *
				 *	This section should be moved to a separate subroutine,
				 *	because a similar function is performed in
				 *	__idetape_discard_read_pipeline(), for example.
				 */
				tape->next_stage = NULL;
				spin_unlock_irqrestore(&tape->spinlock, flags);
				idetape_wait_first_stage(drive);
				tape->next_stage = tape->first_stage->next;
			} else
				spin_unlock_irqrestore(&tape->spinlock, flags);
			if (tape->first_stage->rq.errors == IDETAPE_ERROR_FILEMARK)
				++count;
			idetape_remove_stage_head(drive);
		}
		idetape_discard_read_pipeline(drive, 0);
	}

	/*
	 *	The filemark was not found in our internal pipeline.
	 *	Now we can issue the space command.
	 */
	switch (mt_op) {
		case MTFSF:
		case MTBSF:
			idetape_create_space_cmd(&pc,mt_count-count,IDETAPE_SPACE_OVER_FILEMARK);
			return (idetape_queue_pc_tail(drive, &pc));
		case MTFSFM:
		case MTBSFM:
			if (!tape->capabilities.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 (26 KB on my particular tape).
 *      (32 kB 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 = ide_tape_f(file);
	ide_drive_t *drive = tape->drive;
	ssize_t bytes_read,temp, actually_read = 0, rc;
3726
	ssize_t ret = 0;
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#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 3)
		printk(KERN_INFO "ide-tape: Reached idetape_chrdev_read, count %Zd\n", count);
#endif /* IDETAPE_DEBUG_LOG */

	if (tape->chrdev_direction != idetape_direction_read) {
		if (test_bit(IDETAPE_DETECT_BS, &tape->flags))
			if (count > tape->tape_block_size &&
			    (count % tape->tape_block_size) == 0)
				tape->user_bs_factor = count / tape->tape_block_size;
	}
	if ((rc = idetape_initiate_read(drive, tape->max_stages)) < 0)
		return rc;
	if (count == 0)
		return (0);
	if (tape->merge_stage_size) {
		actually_read = min((unsigned int)(tape->merge_stage_size), (unsigned int)count);
3745 3746
		if (idetape_copy_stage_to_user(tape, buf, tape->merge_stage, actually_read))
			ret = -EFAULT;
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		buf += actually_read;
		tape->merge_stage_size -= actually_read;
		count -= actually_read;
	}
	while (count >= tape->stage_size) {
		bytes_read = idetape_add_chrdev_read_request(drive, tape->capabilities.ctl);
		if (bytes_read <= 0)
			goto finish;
3755 3756
		if (idetape_copy_stage_to_user(tape, buf, tape->merge_stage, bytes_read))
			ret = -EFAULT;
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		buf += bytes_read;
		count -= bytes_read;
		actually_read += bytes_read;
	}
	if (count) {
		bytes_read = idetape_add_chrdev_read_request(drive, tape->capabilities.ctl);
		if (bytes_read <= 0)
			goto finish;
		temp = min((unsigned long)count, (unsigned long)bytes_read);
3766 3767
		if (idetape_copy_stage_to_user(tape, buf, tape->merge_stage, temp))
			ret = -EFAULT;
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		actually_read += temp;
		tape->merge_stage_size = bytes_read-temp;
	}
finish:
	if (!actually_read && test_bit(IDETAPE_FILEMARK, &tape->flags)) {
#if IDETAPE_DEBUG_LOG
		if (tape->debug_level >= 2)
			printk(KERN_INFO "ide-tape: %s: spacing over filemark\n", tape->name);
#endif
		idetape_space_over_filemarks(drive, MTFSF, 1);
		return 0;
	}
3780 3781

	return (ret) ? ret : actually_read;
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}

static ssize_t idetape_chrdev_write (struct file *file, const char __user *buf,
				     size_t count, loff_t *ppos)
{
	struct ide_tape_obj *tape = ide_tape_f(file);
	ide_drive_t *drive = tape->drive;
3789 3790
	ssize_t actually_written = 0;
	ssize_t ret = 0;
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	/* The drive is write protected. */
	if (tape->write_prot)
		return -EACCES;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 3)
		printk(KERN_INFO "ide-tape: Reached idetape_chrdev_write, "
			"count %Zd\n", count);
#endif /* IDETAPE_DEBUG_LOG */

	/* Initialize write operation */
	if (tape->chrdev_direction != idetape_direction_write) {
		if (tape->chrdev_direction == idetape_direction_read)
			idetape_discard_read_pipeline(drive, 1);
#if IDETAPE_DEBUG_BUGS
		if (tape->merge_stage || tape->merge_stage_size) {
			printk(KERN_ERR "ide-tape: merge_stage_size "
				"should be 0 now\n");
			tape->merge_stage_size = 0;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		if ((tape->merge_stage = __idetape_kmalloc_stage(tape, 0, 0)) == NULL)
			return -ENOMEM;
		tape->chrdev_direction = idetape_direction_write;
		idetape_init_merge_stage(tape);

		/*
		 *	Issue a write 0 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->dsc_overlap) {
3826
			ssize_t retval = idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, 0, tape->merge_stage->bh);
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			if (retval < 0) {
				__idetape_kfree_stage(tape->merge_stage);
				tape->merge_stage = NULL;
				tape->chrdev_direction = idetape_direction_none;
				return retval;
			}
		}
	}
	if (count == 0)
		return (0);
	if (tape->restart_speed_control_req)
		idetape_restart_speed_control(drive);
	if (tape->merge_stage_size) {
#if IDETAPE_DEBUG_BUGS
		if (tape->merge_stage_size >= tape->stage_size) {
			printk(KERN_ERR "ide-tape: bug: merge buffer too big\n");
			tape->merge_stage_size = 0;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		actually_written = min((unsigned int)(tape->stage_size - tape->merge_stage_size), (unsigned int)count);
3847 3848
		if (idetape_copy_stage_from_user(tape, tape->merge_stage, buf, actually_written))
				ret = -EFAULT;
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		buf += actually_written;
		tape->merge_stage_size += actually_written;
		count -= actually_written;

		if (tape->merge_stage_size == tape->stage_size) {
3854
			ssize_t retval;
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			tape->merge_stage_size = 0;
			retval = idetape_add_chrdev_write_request(drive, tape->capabilities.ctl);
			if (retval <= 0)
				return (retval);
		}
	}
	while (count >= tape->stage_size) {
3862 3863 3864
		ssize_t retval;
		if (idetape_copy_stage_from_user(tape, tape->merge_stage, buf, tape->stage_size))
			ret = -EFAULT;
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		buf += tape->stage_size;
		count -= tape->stage_size;
		retval = idetape_add_chrdev_write_request(drive, tape->capabilities.ctl);
		actually_written += tape->stage_size;
		if (retval <= 0)
			return (retval);
	}
	if (count) {
		actually_written += count;
3874 3875
		if (idetape_copy_stage_from_user(tape, tape->merge_stage, buf, count))
			ret = -EFAULT;
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		tape->merge_stage_size += count;
	}
3878
	return (ret) ? ret : actually_written;
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}

static int idetape_write_filemark (ide_drive_t *drive)
{
	idetape_pc_t pc;

	/* Write a filemark */
	idetape_create_write_filemark_cmd(drive, &pc, 1);
	if (idetape_queue_pc_tail(drive, &pc)) {
		printk(KERN_ERR "ide-tape: Couldn't write a filemark\n");
		return -EIO;
	}
	return 0;
}

/*
 *	idetape_mtioctop is called from idetape_chrdev_ioctl when
 *	the general mtio MTIOCTOP ioctl is requested.
 *
 *	We currently support the following mtio.h operations:
 *
 *	MTFSF	-	Space over mt_count filemarks in the positive direction.
 *			The tape is positioned after the last spaced filemark.
 *
 *	MTFSFM	-	Same as MTFSF, but the tape is positioned before the
 *			last filemark.
 *
 *	MTBSF	-	Steps background over mt_count filemarks, tape is
 *			positioned before the last filemark.
 *
 *	MTBSFM	-	Like MTBSF, only tape is positioned after the last filemark.
 *
 *	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 (it is
 *		supported in the rare case in which we crossed the filemark
 *		during our read-ahead pipelined operation mode).
 *		
 *	MTWEOF	-	Writes mt_count filemarks. Tape is positioned after
 *			the last written filemark.
 *
 *	MTREW	-	Rewinds tape.
 *
 *	MTLOAD	-	Loads the tape.
 *
 *	MTOFFL	-	Puts the tape drive "Offline": Rewinds the tape and
 *	MTUNLOAD	prevents further access until the media is replaced.
 *
 *	MTNOP	-	Flushes tape buffers.
 *
 *	MTRETEN	-	Retension media. This typically consists of one end
 *			to end pass on the media.
 *
 *	MTEOM	-	Moves to the end of recorded data.
 *
 *	MTERASE	-	Erases tape.
 *
 *	MTSETBLK - 	Sets the user block size to mt_count bytes. If
 *			mt_count is 0, we will attempt to autodetect
 *			the block size.
 *
 *	MTSEEK	-	Positions the tape in a specific block number, where
 *			each block is assumed to contain which user_block_size
 *			bytes.
 *
 *	MTSETPART - 	Switches to another tape partition.
 *
 *	MTLOCK - 	Locks the tape door.
 *
 *	MTUNLOCK - 	Unlocks the tape door.
 *
 *	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;
	idetape_pc_t pc;
	int i,retval;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 1)
		printk(KERN_INFO "ide-tape: Handling MTIOCTOP ioctl: "
			"mt_op=%d, mt_count=%d\n", mt_op, mt_count);
#endif /* IDETAPE_DEBUG_LOG */
	/*
	 *	Commands which need our pipelined read-ahead stages.
	 */
	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;
			idetape_discard_read_pipeline(drive, 1);
			for (i = 0; i < mt_count; i++) {
				retval = idetape_write_filemark(drive);
				if (retval)
					return retval;
			}
			return (0);
		case MTREW:
			idetape_discard_read_pipeline(drive, 0);
			if (idetape_rewind_tape(drive))
				return -EIO;
			return 0;
		case MTLOAD:
			idetape_discard_read_pipeline(drive, 0);
			idetape_create_load_unload_cmd(drive, &pc, IDETAPE_LU_LOAD_MASK);
			return (idetape_queue_pc_tail(drive, &pc));
		case MTUNLOAD:
		case MTOFFL:
			/*
			 * If door is locked, attempt to unlock before
			 * attempting to eject.
			 */
			if (tape->door_locked) {
				if (idetape_create_prevent_cmd(drive, &pc, 0))
					if (!idetape_queue_pc_tail(drive, &pc))
						tape->door_locked = DOOR_UNLOCKED;
			}
			idetape_discard_read_pipeline(drive, 0);
			idetape_create_load_unload_cmd(drive, &pc,!IDETAPE_LU_LOAD_MASK);
			retval = idetape_queue_pc_tail(drive, &pc);
			if (!retval)
				clear_bit(IDETAPE_MEDIUM_PRESENT, &tape->flags);
			return retval;
		case MTNOP:
			idetape_discard_read_pipeline(drive, 0);
			return (idetape_flush_tape_buffers(drive));
		case MTRETEN:
			idetape_discard_read_pipeline(drive, 0);
			idetape_create_load_unload_cmd(drive, &pc,IDETAPE_LU_RETENSION_MASK | IDETAPE_LU_LOAD_MASK);
			return (idetape_queue_pc_tail(drive, &pc));
		case MTEOM:
			idetape_create_space_cmd(&pc, 0, IDETAPE_SPACE_TO_EOD);
			return (idetape_queue_pc_tail(drive, &pc));
		case MTERASE:
			(void) idetape_rewind_tape(drive);
			idetape_create_erase_cmd(&pc);
			return (idetape_queue_pc_tail(drive, &pc));
		case MTSETBLK:
			if (mt_count) {
				if (mt_count < tape->tape_block_size || mt_count % tape->tape_block_size)
					return -EIO;
				tape->user_bs_factor = mt_count / tape->tape_block_size;
				clear_bit(IDETAPE_DETECT_BS, &tape->flags);
			} else
				set_bit(IDETAPE_DETECT_BS, &tape->flags);
			return 0;
		case MTSEEK:
			idetape_discard_read_pipeline(drive, 0);
			return idetape_position_tape(drive, mt_count * tape->user_bs_factor, tape->partition, 0);
		case MTSETPART:
			idetape_discard_read_pipeline(drive, 0);
			return (idetape_position_tape(drive, 0, mt_count, 0));
		case MTFSR:
		case MTBSR:
		case MTLOCK:
			if (!idetape_create_prevent_cmd(drive, &pc, 1))
				return 0;
			retval = idetape_queue_pc_tail(drive, &pc);
			if (retval) return retval;
			tape->door_locked = DOOR_EXPLICITLY_LOCKED;
			return 0;
		case MTUNLOCK:
			if (!idetape_create_prevent_cmd(drive, &pc, 0))
				return 0;
			retval = idetape_queue_pc_tail(drive, &pc);
			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.
 *
 *	The following ioctls are supported:
 *
 *	MTIOCTOP -	Refer to idetape_mtioctop for detailed description.
 *
 *	MTIOCGET - 	The mt_dsreg field in the returned mtget structure
 *			will be set to (user block size in bytes <<
 *			MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK.
 *
 *			The mt_blkno is set to the current user block number.
 *			The other mtget fields are not supported.
 *
 *	MTIOCPOS -	The current tape "block position" is returned. We
 *			assume that each block contains user_block_size
 *			bytes.
 *
 *	Our own ide-tape ioctls are supported on both interfaces.
 */
static int idetape_chrdev_ioctl (struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
	struct ide_tape_obj *tape = ide_tape_f(file);
	ide_drive_t *drive = tape->drive;
	struct mtop mtop;
	struct mtget mtget;
	struct mtpos mtpos;
	int block_offset = 0, position = tape->first_frame_position;
	void __user *argp = (void __user *)arg;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 3)
		printk(KERN_INFO "ide-tape: Reached idetape_chrdev_ioctl, "
			"cmd=%u\n", cmd);
#endif /* IDETAPE_DEBUG_LOG */

	tape->restart_speed_control_req = 1;
	if (tape->chrdev_direction == idetape_direction_write) {
		idetape_empty_write_pipeline(drive);
		idetape_flush_tape_buffers(drive);
	}
	if (cmd == MTIOCGET || cmd == MTIOCPOS) {
		block_offset = idetape_pipeline_size(drive) / (tape->tape_block_size * tape->user_bs_factor);
		if ((position = idetape_read_position(drive)) < 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->tape_block_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);
			}
			if (copy_to_user(argp, &mtget, sizeof(struct mtget)))
				return -EFAULT;
			return 0;
		case MTIOCPOS:
			mtpos.mt_blkno = position / tape->user_bs_factor - block_offset;
			if (copy_to_user(argp, &mtpos, sizeof(struct mtpos)))
				return -EFAULT;
			return 0;
		default:
			if (tape->chrdev_direction == idetape_direction_read)
				idetape_discard_read_pipeline(drive, 1);
			return idetape_blkdev_ioctl(drive, cmd, arg);
	}
}

static void idetape_get_blocksize_from_block_descriptor(ide_drive_t *drive);

/*
 *	Our character device open function.
 */
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;
	idetape_pc_t pc;
	int retval;

	/*
	 * 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 IDETAPE_DEBUG_LOG
	printk(KERN_INFO "ide-tape: Reached idetape_chrdev_open\n");
#endif /* IDETAPE_DEBUG_LOG */
	
	if (i >= MAX_HWIFS * MAX_DRIVES)
		return -ENXIO;

	if (!(tape = ide_tape_chrdev_get(i)))
		return -ENXIO;

	drive = tape->drive;

	filp->private_data = tape;

	if (test_and_set_bit(IDETAPE_BUSY, &tape->flags)) {
		retval = -EBUSY;
		goto out_put_tape;
	}

	retval = idetape_wait_ready(drive, 60 * HZ);
	if (retval) {
		clear_bit(IDETAPE_BUSY, &tape->flags);
		printk(KERN_ERR "ide-tape: %s: drive not ready\n", tape->name);
		goto out_put_tape;
	}

	idetape_read_position(drive);
	if (!test_bit(IDETAPE_ADDRESS_VALID, &tape->flags))
		(void)idetape_rewind_tape(drive);

	if (tape->chrdev_direction != idetape_direction_read)
		clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);

	/* Read block size and write protect status from drive. */
	idetape_get_blocksize_from_block_descriptor(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(IDETAPE_BUSY, &tape->flags);
			retval = -EROFS;
			goto out_put_tape;
		}
	}

	/*
	 * Lock the tape drive door so user can't eject.
	 */
	if (tape->chrdev_direction == idetape_direction_none) {
		if (idetape_create_prevent_cmd(drive, &pc, 1)) {
			if (!idetape_queue_pc_tail(drive, &pc)) {
				if (tape->door_locked != DOOR_EXPLICITLY_LOCKED)
					tape->door_locked = DOOR_LOCKED;
			}
		}
	}
	idetape_restart_speed_control(drive);
	tape->restart_speed_control_req = 0;
	return 0;

out_put_tape:
	ide_tape_put(tape);
	return retval;
}

static void idetape_write_release (ide_drive_t *drive, unsigned int minor)
{
	idetape_tape_t *tape = drive->driver_data;

	idetape_empty_write_pipeline(drive);
	tape->merge_stage = __idetape_kmalloc_stage(tape, 1, 0);
	if (tape->merge_stage != NULL) {
		idetape_pad_zeros(drive, tape->tape_block_size * (tape->user_bs_factor - 1));
		__idetape_kfree_stage(tape->merge_stage);
		tape->merge_stage = NULL;
	}
	idetape_write_filemark(drive);
	idetape_flush_tape_buffers(drive);
	idetape_flush_tape_buffers(drive);
}

/*
 *	Our character device release function.
 */
static int idetape_chrdev_release (struct inode *inode, struct file *filp)
{
	struct ide_tape_obj *tape = ide_tape_f(filp);
	ide_drive_t *drive = tape->drive;
	idetape_pc_t pc;
	unsigned int minor = iminor(inode);

	lock_kernel();
	tape = drive->driver_data;
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 3)
		printk(KERN_INFO "ide-tape: Reached idetape_chrdev_release\n");
#endif /* IDETAPE_DEBUG_LOG */

	if (tape->chrdev_direction == idetape_direction_write)
		idetape_write_release(drive, minor);
	if (tape->chrdev_direction == idetape_direction_read) {
		if (minor < 128)
			idetape_discard_read_pipeline(drive, 1);
		else
			idetape_wait_for_pipeline(drive);
	}
	if (tape->cache_stage != NULL) {
		__idetape_kfree_stage(tape->cache_stage);
		tape->cache_stage = NULL;
	}
	if (minor < 128 && test_bit(IDETAPE_MEDIUM_PRESENT, &tape->flags))
		(void) idetape_rewind_tape(drive);
	if (tape->chrdev_direction == idetape_direction_none) {
		if (tape->door_locked == DOOR_LOCKED) {
			if (idetape_create_prevent_cmd(drive, &pc, 0)) {
				if (!idetape_queue_pc_tail(drive, &pc))
					tape->door_locked = DOOR_UNLOCKED;
			}
		}
	}
	clear_bit(IDETAPE_BUSY, &tape->flags);
	ide_tape_put(tape);
	unlock_kernel();
	return 0;
}

/*
 *	idetape_identify_device is called to check the contents of the
 *	ATAPI IDENTIFY command results. We return:
 *
 *	1	If the tape can be supported by us, based on the information
 *		we have so far.
 *
 *	0 	If this tape driver is not currently supported by us.
 */
static int idetape_identify_device (ide_drive_t *drive)
{
	struct idetape_id_gcw gcw;
	struct hd_driveid *id = drive->id;
#if IDETAPE_DEBUG_INFO
	unsigned short mask,i;
#endif /* IDETAPE_DEBUG_INFO */

	if (drive->id_read == 0)
		return 1;

	*((unsigned short *) &gcw) = id->config;

#if IDETAPE_DEBUG_INFO
	printk(KERN_INFO "ide-tape: Dumping ATAPI Identify Device tape parameters\n");
	printk(KERN_INFO "ide-tape: Protocol Type: ");
	switch (gcw.protocol) {
		case 0: case 1: printk("ATA\n");break;
		case 2:	printk("ATAPI\n");break;
		case 3: printk("Reserved (Unknown to ide-tape)\n");break;
	}
	printk(KERN_INFO "ide-tape: Device Type: %x - ",gcw.device_type);	
	switch (gcw.device_type) {
		case 0: printk("Direct-access Device\n");break;
		case 1: printk("Streaming Tape Device\n");break;
		case 2: case 3: case 4: printk("Reserved\n");break;
		case 5: printk("CD-ROM Device\n");break;
		case 6: printk("Reserved\n");
		case 7: printk("Optical memory Device\n");break;
		case 0x1f: printk("Unknown or no Device type\n");break;
		default: printk("Reserved\n");
	}
	printk(KERN_INFO "ide-tape: Removable: %s",gcw.removable ? "Yes\n":"No\n");	
	printk(KERN_INFO "ide-tape: Command Packet DRQ Type: ");
	switch (gcw.drq_type) {
		case 0: printk("Microprocessor DRQ\n");break;
		case 1: printk("Interrupt DRQ\n");break;
		case 2: printk("Accelerated DRQ\n");break;
		case 3: printk("Reserved\n");break;
	}
	printk(KERN_INFO "ide-tape: Command Packet Size: ");
	switch (gcw.packet_size) {
		case 0: printk("12 bytes\n");break;
		case 1: printk("16 bytes\n");break;
		default: printk("Reserved\n");break;
	}
	printk(KERN_INFO "ide-tape: Model: %.40s\n",id->model);
	printk(KERN_INFO "ide-tape: Firmware Revision: %.8s\n",id->fw_rev);
	printk(KERN_INFO "ide-tape: Serial Number: %.20s\n",id->serial_no);
	printk(KERN_INFO "ide-tape: Write buffer size: %d bytes\n",id->buf_size*512);
	printk(KERN_INFO "ide-tape: DMA: %s",id->capability & 0x01 ? "Yes\n":"No\n");
	printk(KERN_INFO "ide-tape: LBA: %s",id->capability & 0x02 ? "Yes\n":"No\n");
	printk(KERN_INFO "ide-tape: IORDY can be disabled: %s",id->capability & 0x04 ? "Yes\n":"No\n");
	printk(KERN_INFO "ide-tape: IORDY supported: %s",id->capability & 0x08 ? "Yes\n":"Unknown\n");
	printk(KERN_INFO "ide-tape: ATAPI overlap supported: %s",id->capability & 0x20 ? "Yes\n":"No\n");
	printk(KERN_INFO "ide-tape: PIO Cycle Timing Category: %d\n",id->tPIO);
	printk(KERN_INFO "ide-tape: DMA Cycle Timing Category: %d\n",id->tDMA);
	printk(KERN_INFO "ide-tape: Single Word DMA supported modes: ");
	for (i=0,mask=1;i<8;i++,mask=mask << 1) {
		if (id->dma_1word & mask)
			printk("%d ",i);
		if (id->dma_1word & (mask << 8))
			printk("(active) ");
	}
	printk("\n");
	printk(KERN_INFO "ide-tape: Multi Word DMA supported modes: ");
	for (i=0,mask=1;i<8;i++,mask=mask << 1) {
		if (id->dma_mword & mask)
			printk("%d ",i);
		if (id->dma_mword & (mask << 8))
			printk("(active) ");
	}
	printk("\n");
	if (id->field_valid & 0x0002) {
		printk(KERN_INFO "ide-tape: Enhanced PIO Modes: %s\n",
			id->eide_pio_modes & 1 ? "Mode 3":"None");
		printk(KERN_INFO "ide-tape: Minimum Multi-word DMA cycle per word: ");
		if (id->eide_dma_min == 0)
			printk("Not supported\n");
		else
			printk("%d ns\n",id->eide_dma_min);

		printk(KERN_INFO "ide-tape: Manufacturer\'s Recommended Multi-word cycle: ");
		if (id->eide_dma_time == 0)
			printk("Not supported\n");
		else
			printk("%d ns\n",id->eide_dma_time);

		printk(KERN_INFO "ide-tape: Minimum PIO cycle without IORDY: ");
		if (id->eide_pio == 0)
			printk("Not supported\n");
		else
			printk("%d ns\n",id->eide_pio);

		printk(KERN_INFO "ide-tape: Minimum PIO cycle with IORDY: ");
		if (id->eide_pio_iordy == 0)
			printk("Not supported\n");
		else
			printk("%d ns\n",id->eide_pio_iordy);
		
	} else
		printk(KERN_INFO "ide-tape: According to the device, fields 64-70 are not valid.\n");
#endif /* IDETAPE_DEBUG_INFO */

	/* Check that we can support this device */

	if (gcw.protocol !=2 )
		printk(KERN_ERR "ide-tape: Protocol is not ATAPI\n");
	else if (gcw.device_type != 1)
		printk(KERN_ERR "ide-tape: Device type is not set to tape\n");
	else if (!gcw.removable)
		printk(KERN_ERR "ide-tape: The removable flag is not set\n");
	else if (gcw.packet_size != 0) {
		printk(KERN_ERR "ide-tape: Packet size is not 12 bytes long\n");
		if (gcw.packet_size == 1)
			printk(KERN_ERR "ide-tape: Sorry, padding to 16 bytes is still not supported\n");
	} else
		return 1;
	return 0;
}

/*
 * Use INQUIRY to get the firmware revision
 */
static void idetape_get_inquiry_results (ide_drive_t *drive)
{
	char *r;
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t pc;
	idetape_inquiry_result_t *inquiry;
	
	idetape_create_inquiry_cmd(&pc);
	if (idetape_queue_pc_tail(drive, &pc)) {
		printk(KERN_ERR "ide-tape: %s: can't get INQUIRY results\n", tape->name);
		return;
	}
	inquiry = (idetape_inquiry_result_t *) pc.buffer;
	memcpy(tape->vendor_id, inquiry->vendor_id, 8);
	memcpy(tape->product_id, inquiry->product_id, 16);
	memcpy(tape->firmware_revision, inquiry->revision_level, 4);
	ide_fixstring(tape->vendor_id, 10, 0);
	ide_fixstring(tape->product_id, 18, 0);
	ide_fixstring(tape->firmware_revision, 6, 0);
	r = tape->firmware_revision;
	if (*(r + 1) == '.')
		tape->firmware_revision_num = (*r - '0') * 100 + (*(r + 2) - '0') * 10 + *(r + 3) - '0';
	printk(KERN_INFO "ide-tape: %s <-> %s: %s %s rev %s\n", drive->name, tape->name, tape->vendor_id, tape->product_id, tape->firmware_revision);
}

/*
 *	idetape_get_mode_sense_results asks 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;
	idetape_pc_t pc;
	idetape_mode_parameter_header_t *header;
	idetape_capabilities_page_t *capabilities;
	
	idetape_create_mode_sense_cmd(&pc, IDETAPE_CAPABILITIES_PAGE);
	if (idetape_queue_pc_tail(drive, &pc)) {
		printk(KERN_ERR "ide-tape: Can't get tape parameters - assuming some default values\n");
		tape->tape_block_size = 512;
		tape->capabilities.ctl = 52;
		tape->capabilities.speed = 450;
		tape->capabilities.buffer_size = 6 * 52;
		return;
	}
	header = (idetape_mode_parameter_header_t *) pc.buffer;
	capabilities = (idetape_capabilities_page_t *) (pc.buffer + sizeof(idetape_mode_parameter_header_t) + header->bdl);

	capabilities->max_speed = ntohs(capabilities->max_speed);
	capabilities->ctl = ntohs(capabilities->ctl);
	capabilities->speed = ntohs(capabilities->speed);
	capabilities->buffer_size = ntohs(capabilities->buffer_size);

	if (!capabilities->speed) {
		printk(KERN_INFO "ide-tape: %s: overriding capabilities->speed (assuming 650KB/sec)\n", drive->name);
		capabilities->speed = 650;
	}
	if (!capabilities->max_speed) {
		printk(KERN_INFO "ide-tape: %s: overriding capabilities->max_speed (assuming 650KB/sec)\n", drive->name);
		capabilities->max_speed = 650;
	}

	tape->capabilities = *capabilities;		/* Save us a copy */
	if (capabilities->blk512)
		tape->tape_block_size = 512;
	else if (capabilities->blk1024)
		tape->tape_block_size = 1024;

#if IDETAPE_DEBUG_INFO
	printk(KERN_INFO "ide-tape: Dumping the results of the MODE SENSE packet command\n");
	printk(KERN_INFO "ide-tape: Mode Parameter Header:\n");
	printk(KERN_INFO "ide-tape: Mode Data Length - %d\n",header->mode_data_length);
	printk(KERN_INFO "ide-tape: Medium Type - %d\n",header->medium_type);
	printk(KERN_INFO "ide-tape: Device Specific Parameter - %d\n",header->dsp);
	printk(KERN_INFO "ide-tape: Block Descriptor Length - %d\n",header->bdl);
	
	printk(KERN_INFO "ide-tape: Capabilities and Mechanical Status Page:\n");
	printk(KERN_INFO "ide-tape: Page code - %d\n",capabilities->page_code);
	printk(KERN_INFO "ide-tape: Page length - %d\n",capabilities->page_length);
	printk(KERN_INFO "ide-tape: Read only - %s\n",capabilities->ro ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports reverse space - %s\n",capabilities->sprev ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports erase initiated formatting - %s\n",capabilities->efmt ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports QFA two Partition format - %s\n",capabilities->qfa ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports locking the medium - %s\n",capabilities->lock ? "Yes":"No");
	printk(KERN_INFO "ide-tape: The volume is currently locked - %s\n",capabilities->locked ? "Yes":"No");
	printk(KERN_INFO "ide-tape: The device defaults in the prevent state - %s\n",capabilities->prevent ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports ejecting the medium - %s\n",capabilities->eject ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports error correction - %s\n",capabilities->ecc ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports data compression - %s\n",capabilities->cmprs ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports 512 bytes block size - %s\n",capabilities->blk512 ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports 1024 bytes block size - %s\n",capabilities->blk1024 ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports 32768 bytes block size / Restricted byte count for PIO transfers - %s\n",capabilities->blk32768 ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Maximum supported speed in KBps - %d\n",capabilities->max_speed);
	printk(KERN_INFO "ide-tape: Continuous transfer limits in blocks - %d\n",capabilities->ctl);
	printk(KERN_INFO "ide-tape: Current speed in KBps - %d\n",capabilities->speed);	
	printk(KERN_INFO "ide-tape: Buffer size - %d\n",capabilities->buffer_size*512);
#endif /* IDETAPE_DEBUG_INFO */
}

/*
 *	ide_get_blocksize_from_block_descriptor does a mode sense page 0 with block descriptor
 *	and if it succeeds sets the tape block size with the reported value
 */
static void idetape_get_blocksize_from_block_descriptor(ide_drive_t *drive)
{

	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t pc;
	idetape_mode_parameter_header_t *header;
	idetape_parameter_block_descriptor_t *block_descrp;
	
	idetape_create_mode_sense_cmd(&pc, IDETAPE_BLOCK_DESCRIPTOR);
	if (idetape_queue_pc_tail(drive, &pc)) {
		printk(KERN_ERR "ide-tape: Can't get block descriptor\n");
		if (tape->tape_block_size == 0) {
			printk(KERN_WARNING "ide-tape: Cannot deal with zero block size, assume 32k\n");
			tape->tape_block_size =  32768;
		}
		return;
	}
	header = (idetape_mode_parameter_header_t *) pc.buffer;
	block_descrp = (idetape_parameter_block_descriptor_t *) (pc.buffer + sizeof(idetape_mode_parameter_header_t));
	tape->tape_block_size =( block_descrp->length[0]<<16) + (block_descrp->length[1]<<8) + block_descrp->length[2];
	tape->drv_write_prot = (header->dsp & 0x80) >> 7;

#if IDETAPE_DEBUG_INFO
	printk(KERN_INFO "ide-tape: Adjusted block size - %d\n", tape->tape_block_size);
#endif /* IDETAPE_DEBUG_INFO */
}
static void idetape_add_settings (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

/*
 *			drive	setting name	read/write	ioctl	ioctl		data type	min			max			mul_factor			div_factor			data pointer				set function
 */
	ide_add_setting(drive,	"buffer",	SETTING_READ,	-1,	-1,		TYPE_SHORT,	0,			0xffff,			1,				2,				&tape->capabilities.buffer_size,	NULL);
	ide_add_setting(drive,	"pipeline_min",	SETTING_RW,	-1,	-1,		TYPE_INT,	1,			0xffff,			tape->stage_size / 1024,	1,				&tape->min_pipeline,			NULL);
	ide_add_setting(drive,	"pipeline",	SETTING_RW,	-1,	-1,		TYPE_INT,	1,			0xffff,			tape->stage_size / 1024,	1,				&tape->max_stages,			NULL);
	ide_add_setting(drive,	"pipeline_max",	SETTING_RW,	-1,	-1,		TYPE_INT,	1,			0xffff,			tape->stage_size / 1024,	1,				&tape->max_pipeline,			NULL);
	ide_add_setting(drive,	"pipeline_used",SETTING_READ,	-1,	-1,		TYPE_INT,	0,			0xffff,			tape->stage_size / 1024,	1,				&tape->nr_stages,			NULL);
	ide_add_setting(drive,	"pipeline_pending",SETTING_READ,-1,	-1,		TYPE_INT,	0,			0xffff,			tape->stage_size / 1024,	1,				&tape->nr_pending_stages,		NULL);
	ide_add_setting(drive,	"speed",	SETTING_READ,	-1,	-1,		TYPE_SHORT,	0,			0xffff,			1,				1,				&tape->capabilities.speed,		NULL);
	ide_add_setting(drive,	"stage",	SETTING_READ,	-1,	-1,		TYPE_INT,	0,			0xffff,			1,				1024,				&tape->stage_size,			NULL);
	ide_add_setting(drive,	"tdsc",		SETTING_RW,	-1,	-1,		TYPE_INT,	IDETAPE_DSC_RW_MIN,	IDETAPE_DSC_RW_MAX,	1000,				HZ,				&tape->best_dsc_rw_frequency,		NULL);
	ide_add_setting(drive,	"dsc_overlap",	SETTING_RW,	-1,	-1,		TYPE_BYTE,	0,			1,			1,				1,				&drive->dsc_overlap,			NULL);
	ide_add_setting(drive,	"pipeline_head_speed_c",SETTING_READ,	-1,	-1,	TYPE_INT,	0,			0xffff,			1,				1,				&tape->controlled_pipeline_head_speed,	NULL);
	ide_add_setting(drive,	"pipeline_head_speed_u",SETTING_READ,	-1,	-1,	TYPE_INT,	0,			0xffff,			1,				1,				&tape->uncontrolled_pipeline_head_speed,	NULL);
	ide_add_setting(drive,	"avg_speed",	SETTING_READ,	-1,	-1,		TYPE_INT,	0,			0xffff,			1,				1,				&tape->avg_speed,		NULL);
	ide_add_setting(drive,	"debug_level",SETTING_RW,	-1,	-1,		TYPE_INT,	0,			0xffff,			1,				1,				&tape->debug_level,		NULL);
}

/*
 *	ide_setup 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 t1, tmid, tn, t;
	int speed;
	struct idetape_id_gcw gcw;
	int stage_size;
	struct sysinfo si;

	spin_lock_init(&tape->spinlock);
	drive->dsc_overlap = 1;
#ifdef CONFIG_BLK_DEV_IDEPCI
	if (HWIF(drive)->pci_dev != NULL) {
		/*
		 * These two ide-pci host adapters appear to need DSC overlap disabled.
		 * This probably needs further analysis.
		 */
		if ((HWIF(drive)->pci_dev->device == PCI_DEVICE_ID_ARTOP_ATP850UF) ||
		    (HWIF(drive)->pci_dev->device == PCI_DEVICE_ID_TTI_HPT343)) {
			printk(KERN_INFO "ide-tape: %s: disabling DSC overlap\n", tape->name);
		    	drive->dsc_overlap = 0;
		}
	}
#endif /* CONFIG_BLK_DEV_IDEPCI */
	/* Seagate Travan drives do not support DSC overlap. */
	if (strstr(drive->id->model, "Seagate STT3401"))
		drive->dsc_overlap = 0;
	tape->minor = minor;
	tape->name[0] = 'h';
	tape->name[1] = 't';
	tape->name[2] = '0' + minor;
	tape->chrdev_direction = idetape_direction_none;
	tape->pc = tape->pc_stack;
	tape->max_insert_speed = 10000;
	tape->speed_control = 1;
	*((unsigned short *) &gcw) = drive->id->config;
	if (gcw.drq_type == 1)
		set_bit(IDETAPE_DRQ_INTERRUPT, &tape->flags);

	tape->min_pipeline = tape->max_pipeline = tape->max_stages = 10;
	
	idetape_get_inquiry_results(drive);
	idetape_get_mode_sense_results(drive);
	idetape_get_blocksize_from_block_descriptor(drive);
	tape->user_bs_factor = 1;
	tape->stage_size = tape->capabilities.ctl * tape->tape_block_size;
	while (tape->stage_size > 0xffff) {
		printk(KERN_NOTICE "ide-tape: decreasing stage size\n");
		tape->capabilities.ctl /= 2;
		tape->stage_size = tape->capabilities.ctl * tape->tape_block_size;
	}
	stage_size = tape->stage_size;
	tape->pages_per_stage = stage_size / PAGE_SIZE;
	if (stage_size % PAGE_SIZE) {
		tape->pages_per_stage++;
		tape->excess_bh_size = PAGE_SIZE - stage_size % PAGE_SIZE;
	}

	/*
	 *	Select the "best" DSC read/write polling frequency
	 *	and pipeline size.
	 */
	speed = max(tape->capabilities.speed, tape->capabilities.max_speed);

	tape->max_stages = speed * 1000 * 10 / tape->stage_size;

	/*
	 * 	Limit memory use for pipeline to 10% of physical memory
	 */
	si_meminfo(&si);
	if (tape->max_stages * tape->stage_size > si.totalram * si.mem_unit / 10)
		tape->max_stages = si.totalram * si.mem_unit / (10 * tape->stage_size);
	tape->max_stages   = min(tape->max_stages, IDETAPE_MAX_PIPELINE_STAGES);
	tape->min_pipeline = min(tape->max_stages, IDETAPE_MIN_PIPELINE_STAGES);
	tape->max_pipeline = min(tape->max_stages * 2, IDETAPE_MAX_PIPELINE_STAGES);
	if (tape->max_stages == 0)
		tape->max_stages = tape->min_pipeline = tape->max_pipeline = 1;

	t1 = (tape->stage_size * HZ) / (speed * 1000);
	tmid = (tape->capabilities.buffer_size * 32 * HZ) / (speed * 125);
	tn = (IDETAPE_FIFO_THRESHOLD * tape->stage_size * HZ) / (speed * 1000);

	if (tape->max_stages)
		t = tn;
	else
		t = t1;

	/*
	 *	Ensure that the number we got makes sense; limit
	 *	it within IDETAPE_DSC_RW_MIN and IDETAPE_DSC_RW_MAX.
	 */
	tape->best_dsc_rw_frequency = max_t(unsigned long, min_t(unsigned long, t, IDETAPE_DSC_RW_MAX), IDETAPE_DSC_RW_MIN);
	printk(KERN_INFO "ide-tape: %s <-> %s: %dKBps, %d*%dkB buffer, "
		"%dkB pipeline, %lums tDSC%s\n",
		drive->name, tape->name, tape->capabilities.speed,
		(tape->capabilities.buffer_size * 512) / tape->stage_size,
		tape->stage_size / 1024,
		tape->max_stages * tape->stage_size / 1024,
		tape->best_dsc_rw_frequency * 1000 / HZ,
		drive->using_dma ? ", DMA":"");

	idetape_add_settings(drive);
}

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static void ide_tape_remove(ide_drive_t *drive)
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{
	idetape_tape_t *tape = drive->driver_data;

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	ide_unregister_subdriver(drive, tape->driver);
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	ide_unregister_region(tape->disk);

	ide_tape_put(tape);
}

static void ide_tape_release(struct kref *kref)
{
	struct ide_tape_obj *tape = to_ide_tape(kref);
	ide_drive_t *drive = tape->drive;
	struct gendisk *g = tape->disk;

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	BUG_ON(tape->first_stage != NULL || tape->merge_stage_size);

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	drive->dsc_overlap = 0;
	drive->driver_data = NULL;
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	class_device_destroy(idetape_sysfs_class,
			MKDEV(IDETAPE_MAJOR, tape->minor));
	class_device_destroy(idetape_sysfs_class,
			MKDEV(IDETAPE_MAJOR, tape->minor + 128));
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	idetape_devs[tape->minor] = NULL;
	g->private_data = NULL;
	put_disk(g);
	kfree(tape);
}

#ifdef CONFIG_PROC_FS

static int proc_idetape_read_name
	(char *page, char **start, off_t off, int count, int *eof, void *data)
{
	ide_drive_t	*drive = (ide_drive_t *) data;
	idetape_tape_t	*tape = drive->driver_data;
	char		*out = page;
	int		len;

	len = sprintf(out, "%s\n", tape->name);
	PROC_IDE_READ_RETURN(page, start, off, count, eof, len);
}

static ide_proc_entry_t idetape_proc[] = {
	{ "capacity",	S_IFREG|S_IRUGO,	proc_ide_read_capacity, NULL },
	{ "name",	S_IFREG|S_IRUGO,	proc_idetape_read_name,	NULL },
	{ NULL, 0, NULL, NULL }
};

#else

#define	idetape_proc	NULL

#endif

4759
static int ide_tape_probe(ide_drive_t *);
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Linus Torvalds 已提交
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static ide_driver_t idetape_driver = {
4762
	.gen_driver = {
4763
		.owner		= THIS_MODULE,
4764 4765 4766
		.name		= "ide-tape",
		.bus		= &ide_bus_type,
	},
4767 4768
	.probe			= ide_tape_probe,
	.remove			= ide_tape_remove,
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Linus Torvalds 已提交
4769 4770 4771 4772 4773 4774 4775 4776 4777 4778 4779 4780 4781 4782 4783 4784 4785 4786 4787 4788 4789 4790 4791 4792 4793 4794 4795 4796 4797 4798 4799 4800 4801 4802 4803 4804 4805 4806 4807 4808 4809 4810 4811 4812 4813 4814 4815 4816 4817 4818 4819 4820 4821 4822 4823 4824 4825 4826 4827 4828 4829 4830 4831 4832 4833 4834 4835 4836 4837 4838
	.version		= IDETAPE_VERSION,
	.media			= ide_tape,
	.supports_dsc_overlap 	= 1,
	.do_request		= idetape_do_request,
	.end_request		= idetape_end_request,
	.error			= __ide_error,
	.abort			= __ide_abort,
	.proc			= idetape_proc,
};

/*
 *	Our character device supporting functions, passed to register_chrdev.
 */
static struct file_operations idetape_fops = {
	.owner		= THIS_MODULE,
	.read		= idetape_chrdev_read,
	.write		= idetape_chrdev_write,
	.ioctl		= idetape_chrdev_ioctl,
	.open		= idetape_chrdev_open,
	.release	= idetape_chrdev_release,
};

static int idetape_open(struct inode *inode, struct file *filp)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
	struct ide_tape_obj *tape;
	ide_drive_t *drive;

	if (!(tape = ide_tape_get(disk)))
		return -ENXIO;

	drive = tape->drive;

	drive->usage++;

	return 0;
}

static int idetape_release(struct inode *inode, struct file *filp)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
	struct ide_tape_obj *tape = ide_tape_g(disk);
	ide_drive_t *drive = tape->drive;

	drive->usage--;

	ide_tape_put(tape);

	return 0;
}

static int idetape_ioctl(struct inode *inode, struct file *file,
			unsigned int cmd, unsigned long arg)
{
	struct block_device *bdev = inode->i_bdev;
	struct ide_tape_obj *tape = ide_tape_g(bdev->bd_disk);
	ide_drive_t *drive = tape->drive;
	int err = generic_ide_ioctl(drive, file, bdev, cmd, arg);
	if (err == -EINVAL)
		err = idetape_blkdev_ioctl(drive, cmd, arg);
	return err;
}

static struct block_device_operations idetape_block_ops = {
	.owner		= THIS_MODULE,
	.open		= idetape_open,
	.release	= idetape_release,
	.ioctl		= idetape_ioctl,
};

4839
static int ide_tape_probe(ide_drive_t *drive)
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4840 4841 4842 4843 4844 4845 4846 4847 4848 4849 4850 4851 4852 4853 4854 4855 4856 4857 4858 4859 4860 4861 4862
{
	idetape_tape_t *tape;
	struct gendisk *g;
	int minor;

	if (!strstr("ide-tape", drive->driver_req))
		goto failed;
	if (!drive->present)
		goto failed;
	if (drive->media != ide_tape)
		goto failed;
	if (!idetape_identify_device (drive)) {
		printk(KERN_ERR "ide-tape: %s: not supported by this version of ide-tape\n", drive->name);
		goto failed;
	}
	if (drive->scsi) {
		printk("ide-tape: passing drive %s to ide-scsi emulation.\n", drive->name);
		goto failed;
	}
	if (strstr(drive->id->model, "OnStream DI-")) {
		printk(KERN_WARNING "ide-tape: Use drive %s with ide-scsi emulation and osst.\n", drive->name);
		printk(KERN_WARNING "ide-tape: OnStream support will be removed soon from ide-tape!\n");
	}
4863
	tape = (idetape_tape_t *) kzalloc (sizeof (idetape_tape_t), GFP_KERNEL);
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4864 4865 4866 4867 4868 4869 4870 4871 4872 4873 4874
	if (tape == NULL) {
		printk(KERN_ERR "ide-tape: %s: Can't allocate a tape structure\n", drive->name);
		goto failed;
	}

	g = alloc_disk(1 << PARTN_BITS);
	if (!g)
		goto out_free_tape;

	ide_init_disk(g, drive);

4875
	ide_register_subdriver(drive, &idetape_driver);
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4876 4877 4878 4879 4880 4881 4882 4883 4884 4885 4886

	kref_init(&tape->kref);

	tape->drive = drive;
	tape->driver = &idetape_driver;
	tape->disk = g;

	g->private_data = &tape->driver;

	drive->driver_data = tape;

4887
	mutex_lock(&idetape_ref_mutex);
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4888 4889 4890
	for (minor = 0; idetape_devs[minor]; minor++)
		;
	idetape_devs[minor] = tape;
4891
	mutex_unlock(&idetape_ref_mutex);
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	idetape_setup(drive, tape, minor);

4895
	class_device_create(idetape_sysfs_class, NULL,
4896
			MKDEV(IDETAPE_MAJOR, minor), &drive->gendev, "%s", tape->name);
4897
	class_device_create(idetape_sysfs_class, NULL,
4898
			MKDEV(IDETAPE_MAJOR, minor + 128), &drive->gendev, "n%s", tape->name);
4899

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4900 4901 4902 4903
	g->fops = &idetape_block_ops;
	ide_register_region(g);

	return 0;
4904

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4905 4906 4907
out_free_tape:
	kfree(tape);
failed:
4908
	return -ENODEV;
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}

MODULE_DESCRIPTION("ATAPI Streaming TAPE Driver");
MODULE_LICENSE("GPL");

static void __exit idetape_exit (void)
{
4916
	driver_unregister(&idetape_driver.gen_driver);
4917
	class_destroy(idetape_sysfs_class);
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4918 4919 4920
	unregister_chrdev(IDETAPE_MAJOR, "ht");
}

4921
static int __init idetape_init(void)
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4922
{
4923 4924 4925 4926 4927 4928 4929 4930 4931
	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;
	}

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Linus Torvalds 已提交
4932 4933
	if (register_chrdev(IDETAPE_MAJOR, "ht", &idetape_fops)) {
		printk(KERN_ERR "ide-tape: Failed to register character device interface\n");
4934 4935
		error = -EBUSY;
		goto out_free_class;
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Linus Torvalds 已提交
4936
	}
4937 4938 4939 4940 4941 4942 4943 4944 4945 4946 4947 4948 4949

	error = driver_register(&idetape_driver.gen_driver);
	if (error)
		goto out_free_driver;

	return 0;

out_free_driver:
	driver_unregister(&idetape_driver.gen_driver);
out_free_class:
	class_destroy(idetape_sysfs_class);
out:
	return error;
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4950 4951
}

4952
MODULE_ALIAS("ide:*m-tape*");
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4953 4954 4955
module_init(idetape_init);
module_exit(idetape_exit);
MODULE_ALIAS_CHARDEV_MAJOR(IDETAPE_MAJOR);