summaryrefslogtreecommitdiff
path: root/drivers/usb/gadget/storage_common.c
blob: 74300746b9dbce36dc30fb261b55d0da26a6e780 (plain)
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
/*
 * storage_common.c -- Common definitions for mass storage functionality
 *
 * Copyright (C) 2003-2008 Alan Stern
 * Copyeight (C) 2009 Samsung Electronics
 * Author: Michal Nazarewicz (m.nazarewicz@samsung.com)
 *
 * Ported to u-boot:
 * Andrzej Pietrasiewicz <andrzej.p@samsung.com>
 *
 * Code refactoring & cleanup:
 * Łukasz Majewski <l.majewski@samsung.com>
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */


/*
 * This file requires the following identifiers used in USB strings to
 * be defined (each of type pointer to char):
 *  - fsg_string_manufacturer -- name of the manufacturer
 *  - fsg_string_product      -- name of the product
 *  - fsg_string_serial       -- product's serial
 *  - fsg_string_config       -- name of the configuration
 *  - fsg_string_interface    -- name of the interface
 * The first four are only needed when FSG_DESCRIPTORS_DEVICE_STRINGS
 * macro is defined prior to including this file.
 */

/*
 * When FSG_NO_INTR_EP is defined fsg_fs_intr_in_desc and
 * fsg_hs_intr_in_desc objects as well as
 * FSG_FS_FUNCTION_PRE_EP_ENTRIES and FSG_HS_FUNCTION_PRE_EP_ENTRIES
 * macros are not defined.
 *
 * When FSG_NO_DEVICE_STRINGS is defined FSG_STRING_MANUFACTURER,
 * FSG_STRING_PRODUCT, FSG_STRING_SERIAL and FSG_STRING_CONFIG are not
 * defined (as well as corresponding entries in string tables are
 * missing) and FSG_STRING_INTERFACE has value of zero.
 *
 * When FSG_NO_OTG is defined fsg_otg_desc won't be defined.
 */

/*
 * When FSG_BUFFHD_STATIC_BUFFER is defined when this file is included
 * the fsg_buffhd structure's buf field will be an array of FSG_BUFLEN
 * characters rather then a pointer to void.
 */


/* #include <asm/unaligned.h> */


/*
 * Thanks to NetChip Technologies for donating this product ID.
 *
 * DO NOT REUSE THESE IDs with any other driver!!  Ever!!
 * Instead:  allocate your own, using normal USB-IF procedures.
 */
#define FSG_VENDOR_ID	0x0525	/* NetChip */
#define FSG_PRODUCT_ID	0xa4a5	/* Linux-USB File-backed Storage Gadget */

/*-------------------------------------------------------------------------*/

#ifndef DEBUG
#undef VERBOSE_DEBUG
#undef DUMP_MSGS
#endif /* !DEBUG */

#ifdef VERBOSE_DEBUG
#define VLDBG	LDBG
#else
#define VLDBG(lun, fmt, args...) do { } while (0)
#endif /* VERBOSE_DEBUG */

/*
#define LDBG(lun, fmt, args...)   dev_dbg (&(lun)->dev, fmt, ## args)
#define LERROR(lun, fmt, args...) dev_err (&(lun)->dev, fmt, ## args)
#define LWARN(lun, fmt, args...)  dev_warn(&(lun)->dev, fmt, ## args)
#define LINFO(lun, fmt, args...)  dev_info(&(lun)->dev, fmt, ## args)
*/

#define LDBG(lun, fmt, args...) do { } while (0)
#define LERROR(lun, fmt, args...) do { } while (0)
#define LWARN(lun, fmt, args...) do { } while (0)
#define LINFO(lun, fmt, args...) do { } while (0)

/*
 * Keep those macros in sync with those in
 * include/linux/usb/composite.h or else GCC will complain.  If they
 * are identical (the same names of arguments, white spaces in the
 * same places) GCC will allow redefinition otherwise (even if some
 * white space is removed or added) warning will be issued.
 *
 * Those macros are needed here because File Storage Gadget does not
 * include the composite.h header.  For composite gadgets those macros
 * are redundant since composite.h is included any way.
 *
 * One could check whether those macros are already defined (which
 * would indicate composite.h had been included) or not (which would
 * indicate we were in FSG) but this is not done because a warning is
 * desired if definitions here differ from the ones in composite.h.
 *
 * We want the definitions to match and be the same in File Storage
 * Gadget as well as Mass Storage Function (and so composite gadgets
 * using MSF).  If someone changes them in composite.h it will produce
 * a warning in this file when building MSF.
 */

#define DBG(d, fmt, args...)     debug(fmt , ## args)
#define VDBG(d, fmt, args...)    debug(fmt , ## args)
/* #define ERROR(d, fmt, args...)   printf(fmt , ## args) */
/* #define WARNING(d, fmt, args...) printf(fmt , ## args) */
/* #define INFO(d, fmt, args...)    printf(fmt , ## args) */

/* #define DBG(d, fmt, args...)     do { } while (0) */
/* #define VDBG(d, fmt, args...)    do { } while (0) */
#define ERROR(d, fmt, args...)   do { } while (0)
#define WARNING(d, fmt, args...) do { } while (0)
#define INFO(d, fmt, args...)    do { } while (0)

#ifdef DUMP_MSGS

/* dump_msg(fsg, const char * label, const u8 * buf, unsigned length); */
# define dump_msg(fsg, label, buf, length) do {                         \
	if (length < 512) {						\
		DBG(fsg, "%s, length %u:\n", label, length);		\
		print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET,	\
			       16, 1, buf, length, 0);			\
	}								\
} while (0)

#  define dump_cdb(fsg) do { } while (0)

#else

#  define dump_msg(fsg, /* const char * */ label, \
		   /* const u8 * */ buf, /* unsigned */ length) do { } while (0)

#  ifdef VERBOSE_DEBUG

#    define dump_cdb(fsg)						\
	print_hex_dump(KERN_DEBUG, "SCSI CDB: ", DUMP_PREFIX_NONE,	\
		       16, 1, (fsg)->cmnd, (fsg)->cmnd_size, 0)		\

#  else

#    define dump_cdb(fsg) do { } while (0)

#  endif /* VERBOSE_DEBUG */

#endif /* DUMP_MSGS */

/*-------------------------------------------------------------------------*/

/* SCSI device types */
#define TYPE_DISK	0x00
#define TYPE_CDROM	0x05

/* USB protocol value = the transport method */
#define USB_PR_CBI	0x00		/* Control/Bulk/Interrupt */
#define USB_PR_CB	0x01		/* Control/Bulk w/o interrupt */
#define USB_PR_BULK	0x50		/* Bulk-only */

/* USB subclass value = the protocol encapsulation */
#define USB_SC_RBC	0x01		/* Reduced Block Commands (flash) */
#define USB_SC_8020	0x02		/* SFF-8020i, MMC-2, ATAPI (CD-ROM) */
#define USB_SC_QIC	0x03		/* QIC-157 (tape) */
#define USB_SC_UFI	0x04		/* UFI (floppy) */
#define USB_SC_8070	0x05		/* SFF-8070i (removable) */
#define USB_SC_SCSI	0x06		/* Transparent SCSI */

/* Bulk-only data structures */

/* Command Block Wrapper */
struct fsg_bulk_cb_wrap {
	__le32	Signature;		/* Contains 'USBC' */
	u32	Tag;			/* Unique per command id */
	__le32	DataTransferLength;	/* Size of the data */
	u8	Flags;			/* Direction in bit 7 */
	u8	Lun;			/* LUN (normally 0) */
	u8	Length;			/* Of the CDB, <= MAX_COMMAND_SIZE */
	u8	CDB[16];		/* Command Data Block */
};

#define USB_BULK_CB_WRAP_LEN	31
#define USB_BULK_CB_SIG		0x43425355	/* Spells out USBC */
#define USB_BULK_IN_FLAG	0x80

/* Command Status Wrapper */
struct bulk_cs_wrap {
	__le32	Signature;		/* Should = 'USBS' */
	u32	Tag;			/* Same as original command */
	__le32	Residue;		/* Amount not transferred */
	u8	Status;			/* See below */
};

#define USB_BULK_CS_WRAP_LEN	13
#define USB_BULK_CS_SIG		0x53425355	/* Spells out 'USBS' */
#define USB_STATUS_PASS		0
#define USB_STATUS_FAIL		1
#define USB_STATUS_PHASE_ERROR	2

/* Bulk-only class specific requests */
#define USB_BULK_RESET_REQUEST		0xff
#define USB_BULK_GET_MAX_LUN_REQUEST	0xfe

/* CBI Interrupt data structure */
struct interrupt_data {
	u8	bType;
	u8	bValue;
};

#define CBI_INTERRUPT_DATA_LEN		2

/* CBI Accept Device-Specific Command request */
#define USB_CBI_ADSC_REQUEST		0x00

/* Length of a SCSI Command Data Block */
#define MAX_COMMAND_SIZE	16

/* SCSI commands that we recognize */
#define SC_FORMAT_UNIT			0x04
#define SC_INQUIRY			0x12
#define SC_MODE_SELECT_6		0x15
#define SC_MODE_SELECT_10		0x55
#define SC_MODE_SENSE_6			0x1a
#define SC_MODE_SENSE_10		0x5a
#define SC_PREVENT_ALLOW_MEDIUM_REMOVAL	0x1e
#define SC_READ_6			0x08
#define SC_READ_10			0x28
#define SC_READ_12			0xa8
#define SC_READ_CAPACITY		0x25
#define SC_READ_FORMAT_CAPACITIES	0x23
#define SC_READ_HEADER			0x44
#define SC_READ_TOC			0x43
#define SC_RELEASE			0x17
#define SC_REQUEST_SENSE		0x03
#define SC_RESERVE			0x16
#define SC_SEND_DIAGNOSTIC		0x1d
#define SC_START_STOP_UNIT		0x1b
#define SC_SYNCHRONIZE_CACHE		0x35
#define SC_TEST_UNIT_READY		0x00
#define SC_VERIFY			0x2f
#define SC_WRITE_6			0x0a
#define SC_WRITE_10			0x2a
#define SC_WRITE_12			0xaa

/* SCSI Sense Key/Additional Sense Code/ASC Qualifier values */
#define SS_NO_SENSE				0
#define SS_COMMUNICATION_FAILURE		0x040800
#define SS_INVALID_COMMAND			0x052000
#define SS_INVALID_FIELD_IN_CDB			0x052400
#define SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE	0x052100
#define SS_LOGICAL_UNIT_NOT_SUPPORTED		0x052500
#define SS_MEDIUM_NOT_PRESENT			0x023a00
#define SS_MEDIUM_REMOVAL_PREVENTED		0x055302
#define SS_NOT_READY_TO_READY_TRANSITION	0x062800
#define SS_RESET_OCCURRED			0x062900
#define SS_SAVING_PARAMETERS_NOT_SUPPORTED	0x053900
#define SS_UNRECOVERED_READ_ERROR		0x031100
#define SS_WRITE_ERROR				0x030c02
#define SS_WRITE_PROTECTED			0x072700

#define SK(x)		((u8) ((x) >> 16))	/* Sense Key byte, etc. */
#define ASC(x)		((u8) ((x) >> 8))
#define ASCQ(x)		((u8) (x))

struct device_attribute { int i; };
struct rw_semaphore { int i; };
#define down_write(...)			do { } while (0)
#define up_write(...)			do { } while (0)
#define down_read(...)			do { } while (0)
#define up_read(...)			do { } while (0)
#define ETOOSMALL	525

#include <usb_mass_storage.h>

/*-------------------------------------------------------------------------*/

struct fsg_lun {
	loff_t		file_length;
	loff_t		num_sectors;

	unsigned int	initially_ro:1;
	unsigned int	ro:1;
	unsigned int	removable:1;
	unsigned int	cdrom:1;
	unsigned int	prevent_medium_removal:1;
	unsigned int	registered:1;
	unsigned int	info_valid:1;
	unsigned int	nofua:1;

	u32		sense_data;
	u32		sense_data_info;
	u32		unit_attention_data;

	struct device	dev;
};

#define fsg_lun_is_open(curlun)	((curlun)->filp != NULL)
#if 0
static struct fsg_lun *fsg_lun_from_dev(struct device *dev)
{
	return container_of(dev, struct fsg_lun, dev);
}
#endif

/* Big enough to hold our biggest descriptor */
#define EP0_BUFSIZE	256
#define DELAYED_STATUS	(EP0_BUFSIZE + 999)	/* An impossibly large value */

/* Number of buffers we will use.  2 is enough for double-buffering */
#ifndef CONFIG_CI_UDC
#define FSG_NUM_BUFFERS	2
#else
#define FSG_NUM_BUFFERS	1 /* ci_udc only allows 1 req per ep at present */
#endif

/* Default size of buffer length. */
#define FSG_BUFLEN	((u32)16384)

/* Maximal number of LUNs supported in mass storage function */
#define FSG_MAX_LUNS	8

enum fsg_buffer_state {
	BUF_STATE_EMPTY = 0,
	BUF_STATE_FULL,
	BUF_STATE_BUSY
};

struct fsg_buffhd {
#ifdef FSG_BUFFHD_STATIC_BUFFER
	char				buf[FSG_BUFLEN];
#else
	void				*buf;
#endif
	enum fsg_buffer_state		state;
	struct fsg_buffhd		*next;

	/*
	 * The NetChip 2280 is faster, and handles some protocol faults
	 * better, if we don't submit any short bulk-out read requests.
	 * So we will record the intended request length here.
	 */
	unsigned int			bulk_out_intended_length;

	struct usb_request		*inreq;
	int				inreq_busy;
	struct usb_request		*outreq;
	int				outreq_busy;
};

enum fsg_state {
	/* This one isn't used anywhere */
	FSG_STATE_COMMAND_PHASE = -10,
	FSG_STATE_DATA_PHASE,
	FSG_STATE_STATUS_PHASE,

	FSG_STATE_IDLE = 0,
	FSG_STATE_ABORT_BULK_OUT,
	FSG_STATE_RESET,
	FSG_STATE_INTERFACE_CHANGE,
	FSG_STATE_CONFIG_CHANGE,
	FSG_STATE_DISCONNECT,
	FSG_STATE_EXIT,
	FSG_STATE_TERMINATED
};

enum data_direction {
	DATA_DIR_UNKNOWN = 0,
	DATA_DIR_FROM_HOST,
	DATA_DIR_TO_HOST,
	DATA_DIR_NONE
};

/*-------------------------------------------------------------------------*/

static inline u32 get_unaligned_be24(u8 *buf)
{
	return 0xffffff & (u32) get_unaligned_be32(buf - 1);
}

/*-------------------------------------------------------------------------*/

enum {
#ifndef FSG_NO_DEVICE_STRINGS
	FSG_STRING_MANUFACTURER	= 1,
	FSG_STRING_PRODUCT,
	FSG_STRING_SERIAL,
	FSG_STRING_CONFIG,
#endif
	FSG_STRING_INTERFACE
};

#ifndef FSG_NO_OTG
static struct usb_otg_descriptor
fsg_otg_desc = {
	.bLength =		sizeof fsg_otg_desc,
	.bDescriptorType =	USB_DT_OTG,

	.bmAttributes =		USB_OTG_SRP,
};
#endif

/* There is only one interface. */

static struct usb_interface_descriptor
fsg_intf_desc = {
	.bLength =		sizeof fsg_intf_desc,
	.bDescriptorType =	USB_DT_INTERFACE,

	.bNumEndpoints =	2,		/* Adjusted during fsg_bind() */
	.bInterfaceClass =	USB_CLASS_MASS_STORAGE,
	.bInterfaceSubClass =	USB_SC_SCSI,	/* Adjusted during fsg_bind() */
	.bInterfaceProtocol =	USB_PR_BULK,	/* Adjusted during fsg_bind() */
	.iInterface =		FSG_STRING_INTERFACE,
};

/*
 * Three full-speed endpoint descriptors: bulk-in, bulk-out, and
 * interrupt-in.
 */

static struct usb_endpoint_descriptor
fsg_fs_bulk_in_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,

	.bEndpointAddress =	USB_DIR_IN,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
	/* wMaxPacketSize set by autoconfiguration */
};

static struct usb_endpoint_descriptor
fsg_fs_bulk_out_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,

	.bEndpointAddress =	USB_DIR_OUT,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
	/* wMaxPacketSize set by autoconfiguration */
};

#ifndef FSG_NO_INTR_EP

static struct usb_endpoint_descriptor
fsg_fs_intr_in_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,

	.bEndpointAddress =	USB_DIR_IN,
	.bmAttributes =		USB_ENDPOINT_XFER_INT,
	.wMaxPacketSize =	cpu_to_le16(2),
	.bInterval =		32,	/* frames -> 32 ms */
};

#ifndef FSG_NO_OTG
#  define FSG_FS_FUNCTION_PRE_EP_ENTRIES	2
#else
#  define FSG_FS_FUNCTION_PRE_EP_ENTRIES	1
#endif

#endif

static struct usb_descriptor_header *fsg_fs_function[] = {
#ifndef FSG_NO_OTG
	(struct usb_descriptor_header *) &fsg_otg_desc,
#endif
	(struct usb_descriptor_header *) &fsg_intf_desc,
	(struct usb_descriptor_header *) &fsg_fs_bulk_in_desc,
	(struct usb_descriptor_header *) &fsg_fs_bulk_out_desc,
#ifndef FSG_NO_INTR_EP
	(struct usb_descriptor_header *) &fsg_fs_intr_in_desc,
#endif
	NULL,
};

/*
 * USB 2.0 devices need to expose both high speed and full speed
 * descriptors, unless they only run at full speed.
 *
 * That means alternate endpoint descriptors (bigger packets)
 * and a "device qualifier" ... plus more construction options
 * for the configuration descriptor.
 */
static struct usb_endpoint_descriptor
fsg_hs_bulk_in_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,

	/* bEndpointAddress copied from fs_bulk_in_desc during fsg_bind() */
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize =	cpu_to_le16(512),
};

static struct usb_endpoint_descriptor
fsg_hs_bulk_out_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,

	/* bEndpointAddress copied from fs_bulk_out_desc during fsg_bind() */
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
	.wMaxPacketSize =	cpu_to_le16(512),
	.bInterval =		1,	/* NAK every 1 uframe */
};

#ifndef FSG_NO_INTR_EP

static struct usb_endpoint_descriptor
fsg_hs_intr_in_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,

	/* bEndpointAddress copied from fs_intr_in_desc during fsg_bind() */
	.bmAttributes =		USB_ENDPOINT_XFER_INT,
	.wMaxPacketSize =	cpu_to_le16(2),
	.bInterval =		9,	/* 2**(9-1) = 256 uframes -> 32 ms */
};

#ifndef FSG_NO_OTG
#  define FSG_HS_FUNCTION_PRE_EP_ENTRIES	2
#else
#  define FSG_HS_FUNCTION_PRE_EP_ENTRIES	1
#endif

#endif

static struct usb_descriptor_header *fsg_hs_function[] = {
#ifndef FSG_NO_OTG
	(struct usb_descriptor_header *) &fsg_otg_desc,
#endif
	(struct usb_descriptor_header *) &fsg_intf_desc,
	(struct usb_descriptor_header *) &fsg_hs_bulk_in_desc,
	(struct usb_descriptor_header *) &fsg_hs_bulk_out_desc,
#ifndef FSG_NO_INTR_EP
	(struct usb_descriptor_header *) &fsg_hs_intr_in_desc,
#endif
	NULL,
};

/* Maxpacket and other transfer characteristics vary by speed. */
static struct usb_endpoint_descriptor *
fsg_ep_desc(struct usb_gadget *g, struct usb_endpoint_descriptor *fs,
		struct usb_endpoint_descriptor *hs)
{
	if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
		return hs;
	return fs;
}

/* Static strings, in UTF-8 (for simplicity we use only ASCII characters) */
static struct usb_string		fsg_strings[] = {
#ifndef FSG_NO_DEVICE_STRINGS
	{FSG_STRING_MANUFACTURER,	fsg_string_manufacturer},
	{FSG_STRING_PRODUCT,		fsg_string_product},
	{FSG_STRING_SERIAL,		fsg_string_serial},
	{FSG_STRING_CONFIG,		fsg_string_config},
#endif
	{FSG_STRING_INTERFACE,		fsg_string_interface},
	{}
};

static struct usb_gadget_strings	fsg_stringtab = {
	.language	= 0x0409,		/* en-us */
	.strings	= fsg_strings,
};

/*-------------------------------------------------------------------------*/

/*
 * If the next two routines are called while the gadget is registered,
 * the caller must own fsg->filesem for writing.
 */

static int fsg_lun_open(struct fsg_lun *curlun, const char *filename)
{
	int				ro;

	/* R/W if we can, R/O if we must */
	ro = curlun->initially_ro;

	curlun->ro = ro;
	curlun->file_length = ums->num_sectors << 9;
	curlun->num_sectors = ums->num_sectors;
	debug("open backing file: %s\n", filename);

	return 0;
}

static void fsg_lun_close(struct fsg_lun *curlun)
{
}

/*-------------------------------------------------------------------------*/

/*
 * Sync the file data, don't bother with the metadata.
 * This code was copied from fs/buffer.c:sys_fdatasync().
 */
static int fsg_lun_fsync_sub(struct fsg_lun *curlun)
{
	return 0;
}

static void store_cdrom_address(u8 *dest, int msf, u32 addr)
{
	if (msf) {
		/* Convert to Minutes-Seconds-Frames */
		addr >>= 2;		/* Convert to 2048-byte frames */
		addr += 2*75;		/* Lead-in occupies 2 seconds */
		dest[3] = addr % 75;	/* Frames */
		addr /= 75;
		dest[2] = addr % 60;	/* Seconds */
		addr /= 60;
		dest[1] = addr;		/* Minutes */
		dest[0] = 0;		/* Reserved */
	} else {
		/* Absolute sector */
		put_unaligned_be32(addr, dest);
	}
}

/*-------------------------------------------------------------------------*/