Free Electrons

Embedded Linux Experts

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
/* SPDX-License-Identifier: GPL-2.0 */
/*
 *	$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