/*
   *	$Header: /cvsroot/osst/Driver/osst.h,v 1.16 2005/01/01 21:13:35 wriede Exp $
   */
  
  #include <asm/byteorder.h>
  #include <linux/completion.h>
  #include <linux/mutex.h>
  
  /*	FIXME - rename and use the following two types or delete them!
   *              and the types really should go to st.h anyway...
   *	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. 
   */
  #define COMPRESSION_PAGE           0x0f
  #define COMPRESSION_PAGE_LENGTH    16
  
  #define CAPABILITIES_PAGE          0x2a
  #define CAPABILITIES_PAGE_LENGTH   20
  
  #define TAPE_PARAMTR_PAGE          0x2b
  #define TAPE_PARAMTR_PAGE_LENGTH   16
  
  #define NUMBER_RETRIES_PAGE        0x2f
  #define NUMBER_RETRIES_PAGE_LENGTH 4
  
  #define BLOCK_SIZE_PAGE            0x30
  #define BLOCK_SIZE_PAGE_LENGTH     4
  
  #define BUFFER_FILLING_PAGE        0x33
  #define BUFFER_FILLING_PAGE_LENGTH 4
  
  #define VENDOR_IDENT_PAGE          0x36
  #define VENDOR_IDENT_PAGE_LENGTH   8
  
  #define LOCATE_STATUS_PAGE         0x37
  #define LOCATE_STATUS_PAGE_LENGTH  0
  
  #define MODE_HEADER_LENGTH         4
  
  
  /*
   *	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;
  
  /*
   *      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 */
  } osst_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 */
  } osst_parameter_block_descriptor_t;
  
  /*
   *      The Data Compression Page, as returned by the MODE SENSE packet command.
   */
  typedef struct {
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        ps              :1;
          unsigned        reserved0       :1;     /* Reserved */
  	unsigned        page_code       :6;     /* Page Code - Should be 0xf */
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	unsigned        page_code       :6;     /* Page Code - Should be 0xf */
          unsigned        reserved0       :1;     /* Reserved */
          unsigned        ps              :1;
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
          u8              page_length;            /* Page Length - Should be 14 */
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        dce             :1;     /* Data Compression Enable */
          unsigned        dcc             :1;     /* Data Compression Capable */
  	unsigned        reserved2       :6;     /* Reserved */
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	unsigned        reserved2       :6;     /* Reserved */
          unsigned        dcc             :1;     /* Data Compression Capable */
          unsigned        dce             :1;     /* Data Compression Enable */
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        dde             :1;     /* Data Decompression Enable */
          unsigned        red             :2;     /* Report Exception on Decompression */
  	unsigned        reserved3       :5;     /* Reserved */
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	unsigned        reserved3       :5;     /* Reserved */
          unsigned        red             :2;     /* Report Exception on Decompression */
          unsigned        dde             :1;     /* Data Decompression Enable */
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
          u32             ca;                     /* Compression Algorithm */
          u32             da;                     /* Decompression Algorithm */
          u8              reserved[4];            /* Reserved */
  } osst_data_compression_page_t;
  
  /*
   *      The Medium Partition Page, as returned by the MODE SENSE packet command.
   */
  typedef struct {
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        ps              :1;
          unsigned        reserved1_6     :1;     /* Reserved */
  	unsigned        page_code       :6;     /* Page Code - Should be 0x11 */
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	unsigned        page_code       :6;     /* Page Code - Should be 0x11 */
          unsigned        reserved1_6     :1;     /* Reserved */
          unsigned        ps              :1;
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
          u8              page_length;            /* Page Length - Should be 6 */
          u8              map;                    /* Maximum Additional Partitions - Should be 0 */
          u8              apd;                    /* Additional Partitions Defined - Should be 0 */
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        fdp             :1;     /* Fixed Data Partitions */
          unsigned        sdp             :1;     /* Should be 0 */
          unsigned        idp             :1;     /* Should be 0 */
          unsigned        psum            :2;     /* Should be 0 */
  	unsigned        reserved4_012   :3;     /* Reserved */
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	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 */
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
          u8              mfr;                    /* Medium Format Recognition */
          u8              reserved[2];            /* Reserved */
  } osst_medium_partition_page_t;
  
  /*
   *      Capabilities and Mechanical Status Page
   */
  typedef struct {
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        reserved1_67    :2;
  	unsigned        page_code       :6;     /* Page code - Should be 0x2a */
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	unsigned        page_code       :6;     /* Page code - Should be 0x2a */
          unsigned        reserved1_67    :2;
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
          u8              page_length;            /* Page Length - Should be 0x12 */
          u8              reserved2, reserved3;
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        reserved4_67    :2;
          unsigned        sprev           :1;     /* Supports SPACE in the reverse direction */
          unsigned        reserved4_1234  :4;
  	unsigned        ro              :1;     /* Read Only Mode */
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	unsigned        ro              :1;     /* Read Only Mode */
          unsigned        reserved4_1234  :4;
          unsigned        sprev           :1;     /* Supports SPACE in the reverse direction */
          unsigned        reserved4_67    :2;
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        reserved5_67    :2;
          unsigned        qfa             :1;     /* Supports the QFA two partition formats */
          unsigned        reserved5_4     :1;
          unsigned        efmt            :1;     /* Supports ERASE command initiated formatting */
  	unsigned        reserved5_012   :3;
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	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;
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        cmprs           :1;     /* Supports data compression */
          unsigned        ecc             :1;     /* Supports error correction */
  	unsigned        reserved6_45    :2;     /* Reserved */  
          unsigned        eject           :1;     /* The device can eject the volume */
          unsigned        prevent         :1;     /* The device defaults in the prevent state after power up */
          unsigned        locked          :1;     /* The volume is locked */
  	unsigned        lock            :1;     /* Supports locking the volume */
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	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 */
  	unsigned        reserved6_45    :2;     /* Reserved */  
          unsigned        ecc             :1;     /* Supports error correction */
          unsigned        cmprs           :1;     /* Supports data compression */
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        blk32768        :1;     /* slowb - the device restricts the byte count for PIO */
                                                  /* transfers for slow buffer memory ??? */
                                                  /* Also 32768 block size in some cases */
          unsigned        reserved7_3_6   :4;
          unsigned        blk1024         :1;     /* Supports 1024 bytes block size */
          unsigned        blk512          :1;     /* Supports 512 bytes block size */
  	unsigned        reserved7_0     :1;
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	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 */
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
          __be16          max_speed;              /* Maximum speed supported in KBps */
          u8              reserved10, reserved11;
          __be16          ctl;                    /* Continuous Transfer Limit in blocks */
          __be16          speed;                  /* Current Speed, in KBps */
          __be16          buffer_size;            /* Buffer Size, in 512 bytes */
          u8              reserved18, reserved19;
  } osst_capabilities_page_t;
  
  /*
   *      Block Size Page
   */
  typedef struct {
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        ps              :1;
          unsigned        reserved1_6     :1;
  	unsigned        page_code       :6;     /* Page code - Should be 0x30 */
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	unsigned        page_code       :6;     /* Page code - Should be 0x30 */
          unsigned        reserved1_6     :1;
          unsigned        ps              :1;
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
          u8              page_length;            /* Page Length - Should be 2 */
          u8              reserved2;
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        one             :1;
          unsigned        reserved2_6     :1;
          unsigned        record32_5      :1;
          unsigned        record32        :1;
          unsigned        reserved2_23    :2;
          unsigned        play32_5        :1;
  	unsigned        play32          :1;
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	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;
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
  } osst_block_size_page_t;
  
  /*
   *	Tape Parameters Page
   */
  typedef struct {
  #if   defined(__BIG_ENDIAN_BITFIELD)
          unsigned        ps              :1;
          unsigned        reserved1_6     :1;
  	unsigned        page_code       :6;     /* Page code - Should be 0x2b */
  #elif defined(__LITTLE_ENDIAN_BITFIELD)
  	unsigned        page_code       :6;     /* Page code - Should be 0x2b */
          unsigned        reserved1_6     :1;
          unsigned        ps              :1;
  #else
  #error "Please fix <asm/byteorder.h>"
  #endif
  	u8		reserved2;
  	u8		density;
  	u8		reserved3,reserved4;
  	__be16		segtrk;
  	__be16		trks;
  	u8		reserved5,reserved6,reserved7,reserved8,reserved9,reserved10;
  } osst_tape_paramtr_page_t;
  
  /* OnStream definitions */
  
  #define OS_CONFIG_PARTITION     (0xff)
  #define OS_DATA_PARTITION       (0)
  #define OS_PARTITION_VERSION    (1)
  
  /*
   * partition
   */
  typedef struct os_partition_s {
          __u8    partition_num;
          __u8    par_desc_ver;
          __be16  wrt_pass_cntr;
          __be32  first_frame_ppos;
          __be32  last_frame_ppos;
          __be32  eod_frame_ppos;
  } os_partition_t;
  
  /*
   * DAT entry
   */
  typedef struct os_dat_entry_s {
          __be32  blk_sz;
          __be16  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;
  
  /*
   * Frame types
   */
  #define OS_FRAME_TYPE_FILL      (0)
  #define OS_FRAME_TYPE_EOD       (1 << 0)
  #define OS_FRAME_TYPE_MARKER    (1 << 1)
  #define OS_FRAME_TYPE_HEADER    (1 << 3)
  #define OS_FRAME_TYPE_DATA      (1 << 7)
  
  /*
   * AUX
   */
  typedef struct os_aux_s {
          __be32          format_id;              /* hardware compatibility AUX is based on */
          char            application_sig[4];     /* driver used to write this media */
          __be32          hdwr;                   /* reserved */
          __be32          update_frame_cntr;      /* for configuration frame */
          __u8            frame_type;
          __u8            frame_type_reserved;
          __u8            reserved_18_19[2];
          os_partition_t  partition;
          __u8            reserved_36_43[8];
          __be32          frame_seq_num;
          __be32          logical_blk_num_high;
          __be32          logical_blk_num;
          os_dat_t        dat;
          __u8            reserved188_191[4];
          __be32          filemark_cnt;
          __be32          phys_fm;
          __be32          last_mark_ppos;
          __u8            reserved204_223[20];
  
          /*
           * __u8         app_specific[32];
           *
           * Linux specific fields:
           */
           __be32         next_mark_ppos;         /* when known, points to next marker */
  	 __be32		last_mark_lbn;		/* storing log_blk_num of last mark is extends ADR spec */
           __u8           linux_specific[24];
  
          __u8            reserved_256_511[256];
  } os_aux_t;
  
  #define OS_FM_TAB_MAX 1024
  
  typedef struct os_fm_tab_s {
  	__u8		fm_part_num;
  	__u8		reserved_1;
  	__u8		fm_tab_ent_sz;
  	__u8		reserved_3;
  	__be16		fm_tab_ent_cnt;
  	__u8		reserved6_15[10];
  	__be32		fm_tab_ent[OS_FM_TAB_MAX];
  } os_fm_tab_t;
  
  typedef struct os_ext_trk_ey_s {
  	__u8		et_part_num;
  	__u8		fmt;
  	__be16		fm_tab_off;
  	__u8		reserved4_7[4];
  	__be32		last_hlb_hi;
  	__be32		last_hlb;
  	__be32		last_pp;
  	__u8		reserved20_31[12];
  } os_ext_trk_ey_t;
  
  typedef struct os_ext_trk_tb_s {
  	__u8		nr_stream_part;
  	__u8		reserved_1;
  	__u8		et_ent_sz;
  	__u8		reserved3_15[13];
  	os_ext_trk_ey_t	dat_ext_trk_ey;
  	os_ext_trk_ey_t	qfa_ext_trk_ey;
  } os_ext_trk_tb_t;
  
  typedef struct os_header_s {
          char            ident_str[8];
          __u8            major_rev;
          __u8            minor_rev;
  	__be16		ext_trk_tb_off;
          __u8            reserved12_15[4];
          __u8            pt_par_num;
          __u8            pt_reserved1_3[3];
          os_partition_t  partition[16];
  	__be32		cfg_col_width;
  	__be32		dat_col_width;
  	__be32		qfa_col_width;
  	__u8		cartridge[16];
  	__u8		reserved304_511[208];
  	__be32		old_filemark_list[16680/4];		/* in ADR 1.4 __u8 track_table[16680] */
  	os_ext_trk_tb_t	ext_track_tb;
  	__u8		reserved17272_17735[464];
  	os_fm_tab_t	dat_fm_tab;
  	os_fm_tab_t	qfa_fm_tab;
  	__u8		reserved25960_32767[6808];
  } os_header_t;
  
  
  /*
   * OnStream ADRL frame
   */
  #define OS_FRAME_SIZE   (32 * 1024 + 512)
  #define OS_DATA_SIZE    (32 * 1024)
  #define OS_AUX_SIZE     (512)
  //#define OSST_MAX_SG      2
  
  /* The OnStream tape buffer descriptor. */
  struct osst_buffer {
    unsigned char in_use;
    unsigned char dma;	/* DMA-able buffer */
    int buffer_size;
    int buffer_blocks;
    int buffer_bytes;
    int read_pointer;
    int writing;
    int midlevel_result;
    int syscall_result;
    struct osst_request *last_SRpnt;
    struct st_cmdstatus cmdstat;
    struct rq_map_data map_data;
    unsigned char *b_data;
    os_aux_t *aux;               /* onstream AUX structure at end of each block     */
    unsigned short use_sg;       /* zero or number of s/g segments for this adapter */
    unsigned short sg_segs;      /* number of segments in s/g list                  */
    unsigned short orig_sg_segs; /* number of segments allocated at first try       */
    struct scatterlist sg[1];    /* MUST BE last item                               */
  } ;
  
  /* The OnStream tape drive descriptor */
  struct osst_tape {
    struct scsi_driver *driver;
    unsigned capacity;
    struct scsi_device *device;
    struct mutex lock;           /* for serialization */
    struct completion wait;      /* for SCSI commands */
    struct osst_buffer * buffer;
  
    /* Drive characteristics */
    unsigned char omit_blklims;
    unsigned char do_auto_lock;
    unsigned char can_bsr;
    unsigned char can_partitions;
    unsigned char two_fm;
    unsigned char fast_mteom;
    unsigned char restr_dma;
    unsigned char scsi2_logical;
    unsigned char default_drvbuffer;  /* 0xff = don't touch, value 3 bits */
    unsigned char pos_unknown;        /* after reset position unknown */
    int write_threshold;
    int timeout;			/* timeout for normal commands */
    int long_timeout;		/* timeout for commands known to take long time*/
  
    /* Mode characteristics */
    struct st_modedef modes[ST_NBR_MODES];
    int current_mode;
  
    /* Status variables */
    int partition;
    int new_partition;
    int nbr_partitions;    /* zero until partition support enabled */
    struct st_partstat ps[ST_NBR_PARTITIONS];
    unsigned char dirty;
    unsigned char ready;
    unsigned char write_prot;
    unsigned char drv_write_prot;
    unsigned char in_use;
    unsigned char blksize_changed;
    unsigned char density_changed;
    unsigned char compression_changed;
    unsigned char drv_buffer;
    unsigned char density;
    unsigned char door_locked;
    unsigned char rew_at_close;
    unsigned char inited;
    int block_size;
    int min_block;
    int max_block;
    int recover_count;            /* from tape opening */
    int abort_count;
    int write_count;
    int read_count;
    int recover_erreg;            /* from last status call */
    /*
     * OnStream specific data
     */
    int	   os_fw_rev;			       /* the firmware revision * 10000 */
    unsigned char  raw;                          /* flag OnStream raw access (32.5KB block size) */
    unsigned char  poll;                         /* flag that this drive needs polling (IDE|firmware) */
    unsigned char  frame_in_buffer;	       /* flag that the frame as per frame_seq_number
  						* has been read into STp->buffer and is valid */
    int      frame_seq_number;                   /* logical frame number */
    int      logical_blk_num;                    /* logical block number */
    unsigned first_frame_position;               /* physical frame to be transferred to/from host */
    unsigned last_frame_position;                /* physical frame to be transferd to/from tape */
    int      cur_frames;                         /* current number of frames in internal buffer */
    int      max_frames;                         /* max number of frames in internal buffer */
    char     application_sig[5];                 /* application signature */
    unsigned char  fast_open;                    /* flag that reminds us we didn't check headers at open */
    unsigned short wrt_pass_cntr;                /* write pass counter */
    int      update_frame_cntr;                  /* update frame counter */
    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;
    os_header_t * header_cache;		       /* cache is kept for filemark positions */
    int      filemark_cnt;
    int      first_mark_ppos;
    int      last_mark_ppos;
    int      last_mark_lbn;			/* storing log_blk_num of last mark is extends ADR spec */
    int      first_data_ppos;
    int      eod_frame_ppos;
    int      eod_frame_lfa;
    int      write_type;				/* used in write error recovery */
    int      read_error_frame;			/* used in read error recovery */
    unsigned long cmd_start_time;
    unsigned long max_cmd_time;
  
  #if DEBUG
    unsigned char write_pending;
    int nbr_finished;
    int nbr_waits;
    unsigned char last_cmnd[6];
    unsigned char last_sense[16];
  #endif
    struct gendisk *drive;
  } ;
  
  /* scsi tape command */
  struct osst_request {
  	unsigned char cmd[MAX_COMMAND_SIZE];
  	unsigned char sense[SCSI_SENSE_BUFFERSIZE];
  	int result;
  	struct osst_tape *stp;
  	struct completion *waiting;
  	struct bio *bio;
  };
  
  /* Values of write_type */
  #define OS_WRITE_DATA      0
  #define OS_WRITE_EOD       1
  #define OS_WRITE_NEW_MARK  2
  #define OS_WRITE_LAST_MARK 3
  #define OS_WRITE_HEADER    4
  #define OS_WRITE_FILLER    5
  
  /* Additional rw state */
  #define OS_WRITING_COMPLETE 3