ide-tape.c

Linux环境下java编程的经典书籍

	char *b_data;
	int b_count;
	byte *buffer;				/* Data buffer */
	byte *current_position;			/* Pointer into the above buffer */
	ide_startstop_t (*callback) (ide_drive_t *);	/* Called when this packet command is completed */
	byte 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.
 */
#define	PC_ABORT			0	/* Set when an error is considered normal - We won't retry */
#define PC_WAIT_FOR_DSC			1	/* 1 When polling for DSC on a media access command */
#define PC_DMA_RECOMMENDED		2	/* 1 when we prefer to use DMA if possible */
#define	PC_DMA_IN_PROGRESS		3	/* 1 while DMA in progress */
#define	PC_DMA_ERROR			4	/* 1 when encountered problem during DMA */
#define	PC_WRITING			5	/* Data direction */

/*
 *	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 buffer_head *bh;			/* The data buffers */
	struct idetape_stage_s *next;		/* Pointer to the next stage */
	os_aux_t *aux;				/* OnStream aux ptr */
} 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_drive_t *drive;
	devfs_handle_t de_r, de_n;

	/*
	 *	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.
	 */
	idetape_pc_t *pc;			/* Current packet command */
	idetape_pc_t *failed_pc; 		/* Last failed packet command */
	idetape_pc_t pc_stack[IDETAPE_PC_STACK];/* Packet command stack */
	int pc_stack_index;			/* Next free packet command storage space */
	struct request rq_stack[IDETAPE_PC_STACK];
	int rq_stack_index;			/* We implement a circular array */

	/*
	 *	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;
	unsigned long dsc_polling_start;	/* The time in which we started polling for DSC */
	struct timer_list dsc_timer;		/* Timer used to poll for dsc */
	unsigned long best_dsc_rw_frequency;	/* Read/Write dsc polling frequency */
	unsigned long dsc_polling_frequency;	/* The current polling frequency */
	unsigned long dsc_timeout;		/* Maximum waiting time */

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

	/*
	 *	Last error information
	 */
	byte sense_key, asc, ascq;

	/*
	 *	Character device operation
	 */
	unsigned int minor;
	char name[4];					/* device name */
	idetape_chrdev_direction_t chrdev_direction;	/* Current character device data transfer direction */

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

	/*
	 *	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.
	 */
	struct request *active_data_request;	/* Pointer to the request which is waiting in the device request queue */
	int stage_size;				/* Data buffer size (chosen based on the tape's recommendation */
	idetape_stage_t *merge_stage;
	int merge_stage_size;
	struct buffer_head *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).
	 */
	int nr_stages;				/* Number of currently used stages */
	int nr_pending_stages;			/* Number of pending stages */
	int max_stages, min_pipeline, max_pipeline; /* We will not allocate more than this number of stages */
	idetape_stage_t *first_stage;		/* The first stage which will be removed from the pipeline */
	idetape_stage_t *active_stage;		/* The currently active stage */
	idetape_stage_t *next_stage;		/* Will be serviced after the currently active request */
	idetape_stage_t *last_stage;		/* New requests will be added to the pipeline here */
	idetape_stage_t *cache_stage;		/* Optional free stage which we can use */
	int pages_per_stage;
	int excess_bh_size;			/* Wasted space in each stage */

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

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

	idetape_request_sense_result_t sense;	/* last sense information */

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

	int door_locked;			/* the door is currently locked */

	/*
	 * OnStream flags
	 */
	int onstream;				/* the tape is an OnStream tape */
	int raw;				/* OnStream raw access (32.5KB block size) */
	int cur_frames;				/* current number of frames in internal buffer */
	int max_frames;				/* max number of frames in internal buffer */
	int logical_blk_num;			/* logical block number */
	__u16 wrt_pass_cntr;			/* write pass counter */
	__u32 update_frame_cntr;		/* update frame counter */
	struct completion *waiting;
	int onstream_write_error;		/* write error recovery active */
	int header_ok;				/* header frame verified ok */
	int linux_media;			/* reading linux-specifc media */
	int linux_media_version;
	char application_sig[5];		/* application signature */
	int filemark_cnt;
	int first_mark_addr;
	int last_mark_addr;
	int eod_frame_addr;
	unsigned long cmd_start_time;
	unsigned long max_cmd_time;
	unsigned capacity;

	/*
	 * Optimize the number of "buffer filling"
	 * mode sense commands.
	 */
	unsigned long last_buffer_fill;		/* last time in which we issued fill cmd */
	int req_buffer_fill;			/* buffer fill command requested */
	int writes_since_buffer_fill;
	int reads_since_buffer_fill;

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

	/*
	 * Measures number of frames:
	 *
	 * 1. written/read to/from the driver pipeline (pipeline_head).
	 * 2. written/read to/from the tape buffers (buffer_head).
	 * 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, controlled_pipeline_head_speed, uncontrolled_pipeline_head_speed;
	int controlled_last_pipeline_head, uncontrolled_last_pipeline_head;
	unsigned long uncontrolled_pipeline_head_time, controlled_pipeline_head_time;
	int controlled_previous_pipeline_head, uncontrolled_previous_pipeline_head;
	unsigned long controlled_previous_head_time, 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;

/*
 *	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 */

/*
 *	Supported ATAPI tape drives packet commands
 */