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file_storage.c

/*
 * file_storage.c -- File-backed USB Storage Gadget, for USB development
 *
 * Copyright (C) 2003-2008 Alan Stern
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The names of the above-listed copyright holders may not be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * ALTERNATIVELY, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") as published by the Free Software
 * Foundation, either version 2 of that License or (at your option) any
 * later version.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


/*
 * The File-backed Storage Gadget acts as a USB Mass Storage device,
 * appearing to the host as a disk drive or as a CD-ROM drive.  In addition
 * to providing an example of a genuinely useful gadget driver for a USB
 * device, it also illustrates a technique of double-buffering for increased
 * throughput.  Last but not least, it gives an easy way to probe the
 * behavior of the Mass Storage drivers in a USB host.
 *
 * Backing storage is provided by a regular file or a block device, specified
 * by the "file" module parameter.  Access can be limited to read-only by
 * setting the optional "ro" module parameter.  (For CD-ROM emulation,
 * access is always read-only.)  The gadget will indicate that it has
 * removable media if the optional "removable" module parameter is set.
 *
 * The gadget supports the Control-Bulk (CB), Control-Bulk-Interrupt (CBI),
 * and Bulk-Only (also known as Bulk-Bulk-Bulk or BBB) transports, selected
 * by the optional "transport" module parameter.  It also supports the
 * following protocols: RBC (0x01), ATAPI or SFF-8020i (0x02), QIC-157 (0c03),
 * UFI (0x04), SFF-8070i (0x05), and transparent SCSI (0x06), selected by
 * the optional "protocol" module parameter.  In addition, the default
 * Vendor ID, Product ID, and release number can be overridden.
 *
 * There is support for multiple logical units (LUNs), each of which has
 * its own backing file.  The number of LUNs can be set using the optional
 * "luns" module parameter (anywhere from 1 to 8), and the corresponding
 * files are specified using comma-separated lists for "file" and "ro".
 * The default number of LUNs is taken from the number of "file" elements;
 * it is 1 if "file" is not given.  If "removable" is not set then a backing
 * file must be specified for each LUN.  If it is set, then an unspecified
 * or empty backing filename means the LUN's medium is not loaded.  Ideally
 * each LUN would be settable independently as a disk drive or a CD-ROM
 * drive, but currently all LUNs have to be the same type.  The CD-ROM
 * emulation includes a single data track and no audio tracks; hence there
 * need be only one backing file per LUN.  Note also that the CD-ROM block
 * length is set to 512 rather than the more common value 2048.
 *
 * Requirements are modest; only a bulk-in and a bulk-out endpoint are
 * needed (an interrupt-out endpoint is also needed for CBI).  The memory
 * requirement amounts to two 16K buffers, size configurable by a parameter.
 * Support is included for both full-speed and high-speed operation.
 *
 * Note that the driver is slightly non-portable in that it assumes a
 * single memory/DMA buffer will be useable for bulk-in, bulk-out, and
 * interrupt-in endpoints.  With most device controllers this isn't an
 * issue, but there may be some with hardware restrictions that prevent
 * a buffer from being used by more than one endpoint.
 *
 * Module options:
 *
 *    file=filename[,filename...]
 *                      Required if "removable" is not set, names of
 *                            the files or block devices used for
 *                            backing storage
 *    ro=b[,b...]       Default false, booleans for read-only access
 *    removable         Default false, boolean for removable media
 *    luns=N                  Default N = number of filenames, number of
 *                            LUNs to support
 *    stall             Default determined according to the type of
 *                            USB device controller (usually true),
 *                            boolean to permit the driver to halt
 *                            bulk endpoints
 *    cdrom             Default false, boolean for whether to emulate
 *                            a CD-ROM drive
 *    transport=XXX           Default BBB, transport name (CB, CBI, or BBB)
 *    protocol=YYY            Default SCSI, protocol name (RBC, 8020 or
 *                            ATAPI, QIC, UFI, 8070, or SCSI;
 *                            also 1 - 6)
 *    vendor=0xVVVV           Default 0x0525 (NetChip), USB Vendor ID
 *    product=0xPPPP          Default 0xa4a5 (FSG), USB Product ID
 *    release=0xRRRR          Override the USB release number (bcdDevice)
 *    buflen=N          Default N=16384, buffer size used (will be
 *                            rounded down to a multiple of
 *                            PAGE_CACHE_SIZE)
 *
 * If CONFIG_USB_FILE_STORAGE_TEST is not set, only the "file", "ro",
 * "removable", "luns", "stall", and "cdrom" options are available; default
 * values are used for everything else.
 *
 * The pathnames of the backing files and the ro settings are available in
 * the attribute files "file" and "ro" in the lun<n> subdirectory of the
 * gadget's sysfs directory.  If the "removable" option is set, writing to
 * these files will simulate ejecting/loading the medium (writing an empty
 * line means eject) and adjusting a write-enable tab.  Changes to the ro
 * setting are not allowed when the medium is loaded or if CD-ROM emulation
 * is being used.
 *
 * This gadget driver is heavily based on "Gadget Zero" by David Brownell.
 * The driver's SCSI command interface was based on the "Information
 * technology - Small Computer System Interface - 2" document from
 * X3T9.2 Project 375D, Revision 10L, 7-SEP-93, available at
 * <http://www.t10.org/ftp/t10/drafts/s2/s2-r10l.pdf>.  The single exception
 * is opcode 0x23 (READ FORMAT CAPACITIES), which was based on the
 * "Universal Serial Bus Mass Storage Class UFI Command Specification"
 * document, Revision 1.0, December 14, 1998, available at
 * <http://www.usb.org/developers/devclass_docs/usbmass-ufi10.pdf>.
 */


/*
 *                      Driver Design
 *
 * The FSG driver is fairly straightforward.  There is a main kernel
 * thread that handles most of the work.  Interrupt routines field
 * callbacks from the controller driver: bulk- and interrupt-request
 * completion notifications, endpoint-0 events, and disconnect events.
 * Completion events are passed to the main thread by wakeup calls.  Many
 * ep0 requests are handled at interrupt time, but SetInterface,
 * SetConfiguration, and device reset requests are forwarded to the
 * thread in the form of "exceptions" using SIGUSR1 signals (since they
 * should interrupt any ongoing file I/O operations).
 *
 * The thread's main routine implements the standard command/data/status
 * parts of a SCSI interaction.  It and its subroutines are full of tests
 * for pending signals/exceptions -- all this polling is necessary since
 * the kernel has no setjmp/longjmp equivalents.  (Maybe this is an
 * indication that the driver really wants to be running in userspace.)
 * An important point is that so long as the thread is alive it keeps an
 * open reference to the backing file.  This will prevent unmounting
 * the backing file's underlying filesystem and could cause problems
 * during system shutdown, for example.  To prevent such problems, the
 * thread catches INT, TERM, and KILL signals and converts them into
 * an EXIT exception.
 *
 * In normal operation the main thread is started during the gadget's
 * fsg_bind() callback and stopped during fsg_unbind().  But it can also
 * exit when it receives a signal, and there's no point leaving the
 * gadget running when the thread is dead.  So just before the thread
 * exits, it deregisters the gadget driver.  This makes things a little
 * tricky: The driver is deregistered at two places, and the exiting
 * thread can indirectly call fsg_unbind() which in turn can tell the
 * thread to exit.  The first problem is resolved through the use of the
 * REGISTERED atomic bitflag; the driver will only be deregistered once.
 * The second problem is resolved by having fsg_unbind() check
 * fsg->state; it won't try to stop the thread if the state is already
 * FSG_STATE_TERMINATED.
 *
 * To provide maximum throughput, the driver uses a circular pipeline of
 * buffer heads (struct fsg_buffhd).  In principle the pipeline can be
 * arbitrarily long; in practice the benefits don't justify having more
 * than 2 stages (i.e., double buffering).  But it helps to think of the
 * pipeline as being a long one.  Each buffer head contains a bulk-in and
 * a bulk-out request pointer (since the buffer can be used for both
 * output and input -- directions always are given from the host's
 * point of view) as well as a pointer to the buffer and various state
 * variables.
 *
 * Use of the pipeline follows a simple protocol.  There is a variable
 * (fsg->next_buffhd_to_fill) that points to the next buffer head to use.
 * At any time that buffer head may still be in use from an earlier
 * request, so each buffer head has a state variable indicating whether
 * it is EMPTY, FULL, or BUSY.  Typical use involves waiting for the
 * buffer head to be EMPTY, filling the buffer either by file I/O or by
 * USB I/O (during which the buffer head is BUSY), and marking the buffer
 * head FULL when the I/O is complete.  Then the buffer will be emptied
 * (again possibly by USB I/O, during which it is marked BUSY) and
 * finally marked EMPTY again (possibly by a completion routine).
 *
 * A module parameter tells the driver to avoid stalling the bulk
 * endpoints wherever the transport specification allows.  This is
 * necessary for some UDCs like the SuperH, which cannot reliably clear a
 * halt on a bulk endpoint.  However, under certain circumstances the
 * Bulk-only specification requires a stall.  In such cases the driver
 * will halt the endpoint and set a flag indicating that it should clear
 * the halt in software during the next device reset.  Hopefully this
 * will permit everything to work correctly.  Furthermore, although the
 * specification allows the bulk-out endpoint to halt when the host sends
 * too much data, implementing this would cause an unavoidable race.
 * The driver will always use the "no-stall" approach for OUT transfers.
 *
 * One subtle point concerns sending status-stage responses for ep0
 * requests.  Some of these requests, such as device reset, can involve
 * interrupting an ongoing file I/O operation, which might take an
 * arbitrarily long time.  During that delay the host might give up on
 * the original ep0 request and issue a new one.  When that happens the
 * driver should not notify the host about completion of the original
 * request, as the host will no longer be waiting for it.  So the driver
 * assigns to each ep0 request a unique tag, and it keeps track of the
 * tag value of the request associated with a long-running exception
 * (device-reset, interface-change, or configuration-change).  When the
 * exception handler is finished, the status-stage response is submitted
 * only if the current ep0 request tag is equal to the exception request
 * tag.  Thus only the most recently received ep0 request will get a
 * status-stage response.
 *
 * Warning: This driver source file is too long.  It ought to be split up
 * into a header file plus about 3 separate .c files, to handle the details
 * of the Gadget, USB Mass Storage, and SCSI protocols.
 */


/* #define VERBOSE_DEBUG */
/* #define DUMP_MSGS */


#include <linux/blkdev.h>
#include <linux/completion.h>
#include <linux/dcache.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/kref.h>
#include <linux/kthread.h>
#include <linux/limits.h>
#include <linux/rwsem.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/freezer.h>
#include <linux/utsname.h>

#include <asm/unaligned.h>

#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>

#include "gadget_chips.h"



/*
 * Kbuild is not very cooperative with respect to linking separately
 * compiled library objects into one module.  So for now we won't use
 * separate compilation ... ensuring init/exit sections work to shrink
 * the runtime footprint, and giving us at least some parts of what
 * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
 */
#include "usbstring.c"
#include "config.c"
#include "epautoconf.c"

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

#define DRIVER_DESC           "File-backed Storage Gadget"
#define DRIVER_NAME           "g_file_storage"
#define DRIVER_VERSION        "20 November 2008"

static const char longname[] = DRIVER_DESC;
static const char shortname[] = DRIVER_NAME;

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR("Alan Stern");
MODULE_LICENSE("Dual BSD/GPL");

/* 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 DRIVER_VENDOR_ID      0x0525      // NetChip
#define DRIVER_PRODUCT_ID     0xa4a5      // Linux-USB File-backed Storage Gadget


/*
 * This driver assumes self-powered hardware and has no way for users to
 * trigger remote wakeup.  It uses autoconfiguration to select endpoints
 * and endpoint addresses.
 */


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

#define LDBG(lun,fmt,args...) \
      dev_dbg(&(lun)->dev , fmt , ## args)
#define MDBG(fmt,args...) \
      pr_debug(DRIVER_NAME ": " fmt , ## args)

#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 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 MINFO(fmt,args...) \
      pr_info(DRIVER_NAME ": " fmt , ## args)

#define DBG(d, fmt, args...) \
      dev_dbg(&(d)->gadget->dev , fmt , ## args)
#define VDBG(d, fmt, args...) \
      dev_vdbg(&(d)->gadget->dev , fmt , ## args)
#define ERROR(d, fmt, args...) \
      dev_err(&(d)->gadget->dev , fmt , ## args)
#define WARNING(d, fmt, args...) \
      dev_warn(&(d)->gadget->dev , fmt , ## args)
#define INFO(d, fmt, args...) \
      dev_info(&(d)->gadget->dev , fmt , ## args)


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

/* Encapsulate the module parameter settings */

#define MAX_LUNS  8

static struct {
      char        *file[MAX_LUNS];
      int         ro[MAX_LUNS];
      unsigned int      num_filenames;
      unsigned int      num_ros;
      unsigned int      nluns;

      int         removable;
      int         can_stall;
      int         cdrom;

      char        *transport_parm;
      char        *protocol_parm;
      unsigned short    vendor;
      unsigned short    product;
      unsigned short    release;
      unsigned int      buflen;

      int         transport_type;
      char        *transport_name;
      int         protocol_type;
      char        *protocol_name;

} mod_data = {                            // Default values
      .transport_parm         = "BBB",
      .protocol_parm          = "SCSI",
      .removable        = 0,
      .can_stall        = 1,
      .cdrom                  = 0,
      .vendor                 = DRIVER_VENDOR_ID,
      .product          = DRIVER_PRODUCT_ID,
      .release          = 0xffff,   // Use controller chip type
      .buflen                 = 16384,
      };


module_param_array_named(file, mod_data.file, charp, &mod_data.num_filenames,
            S_IRUGO);
MODULE_PARM_DESC(file, "names of backing files or devices");

module_param_array_named(ro, mod_data.ro, bool, &mod_data.num_ros, S_IRUGO);
MODULE_PARM_DESC(ro, "true to force read-only");

module_param_named(luns, mod_data.nluns, uint, S_IRUGO);
MODULE_PARM_DESC(luns, "number of LUNs");

module_param_named(removable, mod_data.removable, bool, S_IRUGO);
MODULE_PARM_DESC(removable, "true to simulate removable media");

module_param_named(stall, mod_data.can_stall, bool, S_IRUGO);
MODULE_PARM_DESC(stall, "false to prevent bulk stalls");

module_param_named(cdrom, mod_data.cdrom, bool, S_IRUGO);
MODULE_PARM_DESC(cdrom, "true to emulate cdrom instead of disk");


/* In the non-TEST version, only the module parameters listed above
 * are available. */
#ifdef CONFIG_USB_FILE_STORAGE_TEST

module_param_named(transport, mod_data.transport_parm, charp, S_IRUGO);
MODULE_PARM_DESC(transport, "type of transport (BBB, CBI, or CB)");

module_param_named(protocol, mod_data.protocol_parm, charp, S_IRUGO);
MODULE_PARM_DESC(protocol, "type of protocol (RBC, 8020, QIC, UFI, "
            "8070, or SCSI)");

module_param_named(vendor, mod_data.vendor, ushort, S_IRUGO);
MODULE_PARM_DESC(vendor, "USB Vendor ID");

module_param_named(product, mod_data.product, ushort, S_IRUGO);
MODULE_PARM_DESC(product, "USB Product ID");

module_param_named(release, mod_data.release, ushort, S_IRUGO);
MODULE_PARM_DESC(release, "USB release number");

module_param_named(buflen, mod_data.buflen, uint, S_IRUGO);
MODULE_PARM_DESC(buflen, "I/O buffer size");

#endif /* CONFIG_USB_FILE_STORAGE_TEST */


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

/* 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 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 */
00484 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


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

/* 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))


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

/*
 * These definitions will permit the compiler to avoid generating code for
 * parts of the driver that aren't used in the non-TEST version.  Even gcc
 * can recognize when a test of a constant expression yields a dead code
 * path.
 */

#ifdef CONFIG_USB_FILE_STORAGE_TEST

#define transport_is_bbb()    (mod_data.transport_type == USB_PR_BULK)
#define transport_is_cbi()    (mod_data.transport_type == USB_PR_CBI)
#define protocol_is_scsi()    (mod_data.protocol_type == USB_SC_SCSI)

#else

#define transport_is_bbb()    1
#define transport_is_cbi()    0
#define protocol_is_scsi()    1

#endif /* CONFIG_USB_FILE_STORAGE_TEST */


00569 struct lun {
      struct file *filp;
      loff_t            file_length;
      loff_t            num_sectors;

      unsigned int      ro : 1;
      unsigned int      prevent_medium_removal : 1;
      unsigned int      registered : 1;
      unsigned int      info_valid : 1;

      u32         sense_data;
      u32         sense_data_info;
      u32         unit_attention_data;

      struct device     dev;
};

#define backing_file_is_open(curlun)      ((curlun)->filp != NULL)

static struct lun *dev_to_lun(struct device *dev)
{
      return container_of(dev, struct lun, dev);
}


/* 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 */
#define NUM_BUFFERS     2

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

00607 struct fsg_buffhd {
      void                    *buf;
      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 {
      FSG_STATE_COMMAND_PHASE = -10,            // This one isn't used anywhere
      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
};

00645 struct fsg_dev {
      /* lock protects: state, all the req_busy's, and cbbuf_cmnd */
      spinlock_t        lock;
      struct usb_gadget *gadget;

      /* filesem protects: backing files in use */
      struct rw_semaphore     filesem;

      /* reference counting: wait until all LUNs are released */
      struct kref       ref;

      struct usb_ep           *ep0;       // Handy copy of gadget->ep0
      struct usb_request      *ep0req;    // For control responses
      unsigned int            ep0_req_tag;
      const char        *ep0req_name;

      struct usb_request      *intreq;    // For interrupt responses
      int               intreq_busy;
      struct fsg_buffhd *intr_buffhd;

      unsigned int            bulk_out_maxpacket;
      enum fsg_state          state;            // For exception handling
      unsigned int            exception_req_tag;

      u8                config, new_config;

      unsigned int            running : 1;
      unsigned int            bulk_in_enabled : 1;
      unsigned int            bulk_out_enabled : 1;
      unsigned int            intr_in_enabled : 1;
      unsigned int            phase_error : 1;
      unsigned int            short_packet_received : 1;
      unsigned int            bad_lun_okay : 1;

      unsigned long           atomic_bitflags;
#define REGISTERED            0
#define IGNORE_BULK_OUT       1
#define SUSPENDED       2

      struct usb_ep           *bulk_in;
      struct usb_ep           *bulk_out;
      struct usb_ep           *intr_in;

      struct fsg_buffhd *next_buffhd_to_fill;
      struct fsg_buffhd *next_buffhd_to_drain;
      struct fsg_buffhd buffhds[NUM_BUFFERS];

      int               thread_wakeup_needed;
      struct completion thread_notifier;
      struct task_struct      *thread_task;

      int               cmnd_size;
      u8                cmnd[MAX_COMMAND_SIZE];
      enum data_direction     data_dir;
      u32               data_size;
      u32               data_size_from_cmnd;
      u32               tag;
      unsigned int            lun;
      u32               residue;
      u32               usb_amount_left;

      /* The CB protocol offers no way for a host to know when a command
       * has completed.  As a result the next command may arrive early,
       * and we will still have to handle it.  For that reason we need
       * a buffer to store new commands when using CB (or CBI, which
       * does not oblige a host to wait for command completion either). */
      int               cbbuf_cmnd_size;
      u8                cbbuf_cmnd[MAX_COMMAND_SIZE];

      unsigned int            nluns;
      struct lun        *luns;
      struct lun        *curlun;
};

typedef void (*fsg_routine_t)(struct fsg_dev *);

static int exception_in_progress(struct fsg_dev *fsg)
{
      return (fsg->state > FSG_STATE_IDLE);
}

/* Make bulk-out requests be divisible by the maxpacket size */
static void set_bulk_out_req_length(struct fsg_dev *fsg,
            struct fsg_buffhd *bh, unsigned int length)
{
      unsigned int      rem;

      bh->bulk_out_intended_length = length;
      rem = length % fsg->bulk_out_maxpacket;
      if (rem > 0)
            length += fsg->bulk_out_maxpacket - rem;
      bh->outreq->length = length;
}

static struct fsg_dev               *the_fsg;
static struct usb_gadget_driver           fsg_driver;

static void close_backing_file(struct lun *curlun);


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

#ifdef DUMP_MSGS

static void dump_msg(struct fsg_dev *fsg, const char *label,
            const u8 *buf, unsigned int length)
{
      if (length < 512) {
            DBG(fsg, "%s, length %u:\n", label, length);
            print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET,
                        16, 1, buf, length, 0);
      }
}

static void dump_cdb(struct fsg_dev *fsg)
{}

#else

static void dump_msg(struct fsg_dev *fsg, const char *label,
            const u8 *buf, unsigned int length)
{}

#ifdef VERBOSE_DEBUG

static void dump_cdb(struct fsg_dev *fsg)
{
      print_hex_dump(KERN_DEBUG, "SCSI CDB: ", DUMP_PREFIX_NONE,
                  16, 1, fsg->cmnd, fsg->cmnd_size, 0);
}

#else

static void dump_cdb(struct fsg_dev *fsg)
{}

#endif /* VERBOSE_DEBUG */
#endif /* DUMP_MSGS */


static int fsg_set_halt(struct fsg_dev *fsg, struct usb_ep *ep)
{
      const char  *name;

      if (ep == fsg->bulk_in)
            name = "bulk-in";
      else if (ep == fsg->bulk_out)
            name = "bulk-out";
      else
            name = ep->name;
      DBG(fsg, "%s set halt\n", name);
      return usb_ep_set_halt(ep);
}


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

/* Routines for unaligned data access */

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


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

/*
 * DESCRIPTORS ... most are static, but strings and (full) configuration
 * descriptors are built on demand.  Also the (static) config and interface
 * descriptors are adjusted during fsg_bind().
 */
#define STRING_MANUFACTURER   1
#define STRING_PRODUCT        2
#define STRING_SERIAL         3
#define STRING_CONFIG         4
#define STRING_INTERFACE      5

/* There is only one configuration. */
#define     CONFIG_VALUE            1

static struct usb_device_descriptor
device_desc = {
      .bLength =        sizeof device_desc,
      .bDescriptorType =      USB_DT_DEVICE,

      .bcdUSB =         cpu_to_le16(0x0200),
      .bDeviceClass =         USB_CLASS_PER_INTERFACE,

      /* The next three values can be overridden by module parameters */
      .idVendor =       cpu_to_le16(DRIVER_VENDOR_ID),
      .idProduct =            cpu_to_le16(DRIVER_PRODUCT_ID),
      .bcdDevice =            cpu_to_le16(0xffff),

      .iManufacturer =  STRING_MANUFACTURER,
      .iProduct =       STRING_PRODUCT,
      .iSerialNumber =  STRING_SERIAL,
      .bNumConfigurations =   1,
};

static struct usb_config_descriptor
config_desc = {
      .bLength =        sizeof config_desc,
      .bDescriptorType =      USB_DT_CONFIG,

      /* wTotalLength computed by usb_gadget_config_buf() */
      .bNumInterfaces = 1,
      .bConfigurationValue =  CONFIG_VALUE,
      .iConfiguration = STRING_CONFIG,
      .bmAttributes =         USB_CONFIG_ATT_ONE | USB_CONFIG_ATT_SELFPOWER,
      .bMaxPower =            CONFIG_USB_GADGET_VBUS_DRAW / 2,
};

static struct usb_otg_descriptor
otg_desc = {
      .bLength =        sizeof(otg_desc),
      .bDescriptorType =      USB_DT_OTG,

      .bmAttributes =         USB_OTG_SRP,
};

/* There is only one interface. */

static struct usb_interface_descriptor
intf_desc = {
      .bLength =        sizeof 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 =           STRING_INTERFACE,
};

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

static struct usb_endpoint_descriptor
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
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 */
};

static struct usb_endpoint_descriptor
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
};

static const struct usb_descriptor_header *fs_function[] = {
      (struct usb_descriptor_header *) &otg_desc,
      (struct usb_descriptor_header *) &intf_desc,
      (struct usb_descriptor_header *) &fs_bulk_in_desc,
      (struct usb_descriptor_header *) &fs_bulk_out_desc,
      (struct usb_descriptor_header *) &fs_intr_in_desc,
      NULL,
};
#define FS_FUNCTION_PRE_EP_ENTRIES  2


/*
 * 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 config descriptor.
 */
static struct usb_qualifier_descriptor
dev_qualifier = {
      .bLength =        sizeof dev_qualifier,
      .bDescriptorType =      USB_DT_DEVICE_QUALIFIER,

      .bcdUSB =         cpu_to_le16(0x0200),
      .bDeviceClass =         USB_CLASS_PER_INTERFACE,

      .bNumConfigurations =   1,
};

static struct usb_endpoint_descriptor
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
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
};

static struct usb_endpoint_descriptor
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
};

static const struct usb_descriptor_header *hs_function[] = {
      (struct usb_descriptor_header *) &otg_desc,
      (struct usb_descriptor_header *) &intf_desc,
      (struct usb_descriptor_header *) &hs_bulk_in_desc,
      (struct usb_descriptor_header *) &hs_bulk_out_desc,
      (struct usb_descriptor_header *) &hs_intr_in_desc,
      NULL,
};
#define HS_FUNCTION_PRE_EP_ENTRIES  2

/* Maxpacket and other transfer characteristics vary by speed. */
static struct usb_endpoint_descriptor *
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;
}


/* The CBI specification limits the serial string to 12 uppercase hexadecimal
 * characters. */
static char                   manufacturer[64];
static char                   serial[13];

/* Static strings, in UTF-8 (for simplicity we use only ASCII characters) */
static struct usb_string            strings[] = {
      {STRING_MANUFACTURER,   manufacturer},
      {STRING_PRODUCT,  longname},
      {STRING_SERIAL,         serial},
      {STRING_CONFIG,         "Self-powered"},
      {STRING_INTERFACE,      "Mass Storage"},
      {}
};

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


/*
 * Config descriptors must agree with the code that sets configurations
 * and with code managing interfaces and their altsettings.  They must
 * also handle different speeds and other-speed requests.
 */
static int populate_config_buf(struct usb_gadget *gadget,
            u8 *buf, u8 type, unsigned index)
{
      enum usb_device_speed               speed = gadget->speed;
      int                           len;
      const struct usb_descriptor_header  **function;

      if (index > 0)
            return -EINVAL;

      if (gadget_is_dualspeed(gadget) && type == USB_DT_OTHER_SPEED_CONFIG)
            speed = (USB_SPEED_FULL + USB_SPEED_HIGH) - speed;
      if (gadget_is_dualspeed(gadget) && speed == USB_SPEED_HIGH)
            function = hs_function;
      else
            function = fs_function;

      /* for now, don't advertise srp-only devices */
      if (!gadget_is_otg(gadget))
            function++;

      len = usb_gadget_config_buf(&config_desc, buf, EP0_BUFSIZE, function);
      ((struct usb_config_descriptor *) buf)->bDescriptorType = type;
      return len;
}


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

/* These routines may be called in process context or in_irq */

/* Caller must hold fsg->lock */
static void wakeup_thread(struct fsg_dev *fsg)
{
      /* Tell the main thread that something has happened */
      fsg->thread_wakeup_needed = 1;
      if (fsg->thread_task)
            wake_up_process(fsg->thread_task);
}


static void raise_exception(struct fsg_dev *fsg, enum fsg_state new_state)
{
      unsigned long           flags;

      /* Do nothing if a higher-priority exception is already in progress.
       * If a lower-or-equal priority exception is in progress, preempt it
       * and notify the main thread by sending it a signal. */
      spin_lock_irqsave(&fsg->lock, flags);
      if (fsg->state <= new_state) {
            fsg->exception_req_tag = fsg->ep0_req_tag;
            fsg->state = new_state;
            if (fsg->thread_task)
                  send_sig_info(SIGUSR1, SEND_SIG_FORCED,
                              fsg->thread_task);
      }
      spin_unlock_irqrestore(&fsg->lock, flags);
}


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

/* The disconnect callback and ep0 routines.  These always run in_irq,
 * except that ep0_queue() is called in the main thread to acknowledge
 * completion of various requests: set config, set interface, and
 * Bulk-only device reset. */

static void fsg_disconnect(struct usb_gadget *gadget)
{
      struct fsg_dev          *fsg = get_gadget_data(gadget);

      DBG(fsg, "disconnect or port reset\n");
      raise_exception(fsg, FSG_STATE_DISCONNECT);
}


static int ep0_queue(struct fsg_dev *fsg)
{
      int   rc;

      rc = usb_ep_queue(fsg->ep0, fsg->ep0req, GFP_ATOMIC);
      if (rc != 0 && rc != -ESHUTDOWN) {

            /* We can't do much more than wait for a reset */
            WARNING(fsg, "error in submission: %s --> %d\n",
                        fsg->ep0->name, rc);
      }
      return rc;
}

static void ep0_complete(struct usb_ep *ep, struct usb_request *req)
{
      struct fsg_dev          *fsg = ep->driver_data;

      if (req->actual > 0)
            dump_msg(fsg, fsg->ep0req_name, req->buf, req->actual);
      if (req->status || req->actual != req->length)
            DBG(fsg, "%s --> %d, %u/%u\n", __func__,
                        req->status, req->actual, req->length);
      if (req->status == -ECONNRESET)           // Request was cancelled
            usb_ep_fifo_flush(ep);

      if (req->status == 0 && req->context)
            ((fsg_routine_t) (req->context))(fsg);
}


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

/* Bulk and interrupt endpoint completion handlers.
 * These always run in_irq. */

static void bulk_in_complete(struct usb_ep *ep, struct usb_request *req)
{
      struct fsg_dev          *fsg = ep->driver_data;
      struct fsg_buffhd *bh = req->context;

      if (req->status || req->actual != req->length)
            DBG(fsg, "%s --> %d, %u/%u\n", __func__,
                        req->status, req->actual, req->length);
      if (req->status == -ECONNRESET)           // Request was cancelled
            usb_ep_fifo_flush(ep);

      /* Hold the lock while we update the request and buffer states */
      smp_wmb();
      spin_lock(&fsg->lock);
      bh->inreq_busy = 0;
      bh->state = BUF_STATE_EMPTY;
      wakeup_thread(fsg);
      spin_unlock(&fsg->lock);
}

static void bulk_out_complete(struct usb_ep *ep, struct usb_request *req)
{
      struct fsg_dev          *fsg = ep->driver_data;
      struct fsg_buffhd *bh = req->context;

      dump_msg(fsg, "bulk-out", req->buf, req->actual);
      if (req->status || req->actual != bh->bulk_out_intended_length)
            DBG(fsg, "%s --> %d, %u/%u\n", __func__,
                        req->status, req->actual,
                        bh->bulk_out_intended_length);
      if (req->status == -ECONNRESET)           // Request was cancelled
            usb_ep_fifo_flush(ep);

      /* Hold the lock while we update the request and buffer states */
      smp_wmb();
      spin_lock(&fsg->lock);
      bh->outreq_busy = 0;
      bh->state = BUF_STATE_FULL;
      wakeup_thread(fsg);
      spin_unlock(&fsg->lock);
}


#ifdef CONFIG_USB_FILE_STORAGE_TEST
static void intr_in_complete(struct usb_ep *ep, struct usb_request *req)
{
      struct fsg_dev          *fsg = ep->driver_data;
      struct fsg_buffhd *bh = req->context;

      if (req->status || req->actual != req->length)
            DBG(fsg, "%s --> %d, %u/%u\n", __func__,
                        req->status, req->actual, req->length);
      if (req->status == -ECONNRESET)           // Request was cancelled
            usb_ep_fifo_flush(ep);

      /* Hold the lock while we update the request and buffer states */
      smp_wmb();
      spin_lock(&fsg->lock);
      fsg->intreq_busy = 0;
      bh->state = BUF_STATE_EMPTY;
      wakeup_thread(fsg);
      spin_unlock(&fsg->lock);
}

#else
static void intr_in_complete(struct usb_ep *ep, struct usb_request *req)
{}
#endif /* CONFIG_USB_FILE_STORAGE_TEST */


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

/* Ep0 class-specific handlers.  These always run in_irq. */

#ifdef CONFIG_USB_FILE_STORAGE_TEST
static void received_cbi_adsc(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
      struct usb_request      *req = fsg->ep0req;
      static u8         cbi_reset_cmnd[6] = {
                  SC_SEND_DIAGNOSTIC, 4, 0xff, 0xff, 0xff, 0xff};

      /* Error in command transfer? */
      if (req->status || req->length != req->actual ||
                  req->actual < 6 || req->actual > MAX_COMMAND_SIZE) {

            /* Not all controllers allow a protocol stall after
             * receiving control-out data, but we'll try anyway. */
            fsg_set_halt(fsg, fsg->ep0);
            return;                 // Wait for reset
      }

      /* Is it the special reset command? */
      if (req->actual >= sizeof cbi_reset_cmnd &&
                  memcmp(req->buf, cbi_reset_cmnd,
                        sizeof cbi_reset_cmnd) == 0) {

            /* Raise an exception to stop the current operation
             * and reinitialize our state. */
            DBG(fsg, "cbi reset request\n");
            raise_exception(fsg, FSG_STATE_RESET);
            return;
      }

      VDBG(fsg, "CB[I] accept device-specific command\n");
      spin_lock(&fsg->lock);

      /* Save the command for later */
      if (fsg->cbbuf_cmnd_size)
            WARNING(fsg, "CB[I] overwriting previous command\n");
      fsg->cbbuf_cmnd_size = req->actual;
      memcpy(fsg->cbbuf_cmnd, req->buf, fsg->cbbuf_cmnd_size);

      wakeup_thread(fsg);
      spin_unlock(&fsg->lock);
}

#else
static void received_cbi_adsc(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{}
#endif /* CONFIG_USB_FILE_STORAGE_TEST */


static int class_setup_req(struct fsg_dev *fsg,
            const struct usb_ctrlrequest *ctrl)
{
      struct usb_request      *req = fsg->ep0req;
      int               value = -EOPNOTSUPP;
      u16               w_index = le16_to_cpu(ctrl->wIndex);
      u16                     w_value = le16_to_cpu(ctrl->wValue);
      u16               w_length = le16_to_cpu(ctrl->wLength);

      if (!fsg->config)
            return value;

      /* Handle Bulk-only class-specific requests */
      if (transport_is_bbb()) {
            switch (ctrl->bRequest) {

            case USB_BULK_RESET_REQUEST:
                  if (ctrl->bRequestType != (USB_DIR_OUT |
                              USB_TYPE_CLASS | USB_RECIP_INTERFACE))
                        break;
                  if (w_index != 0 || w_value != 0) {
                        value = -EDOM;
                        break;
                  }

                  /* Raise an exception to stop the current operation
                   * and reinitialize our state. */
                  DBG(fsg, "bulk reset request\n");
                  raise_exception(fsg, FSG_STATE_RESET);
                  value = DELAYED_STATUS;
                  break;

            case USB_BULK_GET_MAX_LUN_REQUEST:
                  if (ctrl->bRequestType != (USB_DIR_IN |
                              USB_TYPE_CLASS | USB_RECIP_INTERFACE))
                        break;
                  if (w_index != 0 || w_value != 0) {
                        value = -EDOM;
                        break;
                  }
                  VDBG(fsg, "get max LUN\n");
                  *(u8 *) req->buf = fsg->nluns - 1;
                  value = 1;
                  break;
            }
      }

      /* Handle CBI class-specific requests */
      else {
            switch (ctrl->bRequest) {

            case USB_CBI_ADSC_REQUEST:
                  if (ctrl->bRequestType != (USB_DIR_OUT |
                              USB_TYPE_CLASS | USB_RECIP_INTERFACE))
                        break;
                  if (w_index != 0 || w_value != 0) {
                        value = -EDOM;
                        break;
                  }
                  if (w_length > MAX_COMMAND_SIZE) {
                        value = -EOVERFLOW;
                        break;
                  }
                  value = w_length;
                  fsg->ep0req->context = received_cbi_adsc;
                  break;
            }
      }

      if (value == -EOPNOTSUPP)
            VDBG(fsg,
                  "unknown class-specific control req "
                  "%02x.%02x v%04x i%04x l%u\n",
                  ctrl->bRequestType, ctrl->bRequest,
                  le16_to_cpu(ctrl->wValue), w_index, w_length);
      return value;
}


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

/* Ep0 standard request handlers.  These always run in_irq. */

static int standard_setup_req(struct fsg_dev *fsg,
            const struct usb_ctrlrequest *ctrl)
{
      struct usb_request      *req = fsg->ep0req;
      int               value = -EOPNOTSUPP;
      u16               w_index = le16_to_cpu(ctrl->wIndex);
      u16               w_value = le16_to_cpu(ctrl->wValue);

      /* Usually this just stores reply data in the pre-allocated ep0 buffer,
       * but config change events will also reconfigure hardware. */
      switch (ctrl->bRequest) {

      case USB_REQ_GET_DESCRIPTOR:
            if (ctrl->bRequestType != (USB_DIR_IN | USB_TYPE_STANDARD |
                        USB_RECIP_DEVICE))
                  break;
            switch (w_value >> 8) {

            case USB_DT_DEVICE:
                  VDBG(fsg, "get device descriptor\n");
                  value = sizeof device_desc;
                  memcpy(req->buf, &device_desc, value);
                  break;
            case USB_DT_DEVICE_QUALIFIER:
                  VDBG(fsg, "get device qualifier\n");
                  if (!gadget_is_dualspeed(fsg->gadget))
                        break;
                  value = sizeof dev_qualifier;
                  memcpy(req->buf, &dev_qualifier, value);
                  break;

            case USB_DT_OTHER_SPEED_CONFIG:
                  VDBG(fsg, "get other-speed config descriptor\n");
                  if (!gadget_is_dualspeed(fsg->gadget))
                        break;
                  goto get_config;
            case USB_DT_CONFIG:
                  VDBG(fsg, "get configuration descriptor\n");
get_config:
                  value = populate_config_buf(fsg->gadget,
                              req->buf,
                              w_value >> 8,
                              w_value & 0xff);
                  break;

            case USB_DT_STRING:
                  VDBG(fsg, "get string descriptor\n");

                  /* wIndex == language code */
                  value = usb_gadget_get_string(&stringtab,
                              w_value & 0xff, req->buf);
                  break;
            }
            break;

      /* One config, two speeds */
      case USB_REQ_SET_CONFIGURATION:
            if (ctrl->bRequestType != (USB_DIR_OUT | USB_TYPE_STANDARD |
                        USB_RECIP_DEVICE))
                  break;
            VDBG(fsg, "set configuration\n");
            if (w_value == CONFIG_VALUE || w_value == 0) {
                  fsg->new_config = w_value;

                  /* Raise an exception to wipe out previous transaction
                   * state (queued bufs, etc) and set the new config. */
                  raise_exception(fsg, FSG_STATE_CONFIG_CHANGE);
                  value = DELAYED_STATUS;
            }
            break;
      case USB_REQ_GET_CONFIGURATION:
            if (ctrl->bRequestType != (USB_DIR_IN | USB_TYPE_STANDARD |
                        USB_RECIP_DEVICE))
                  break;
            VDBG(fsg, "get configuration\n");
            *(u8 *) req->buf = fsg->config;
            value = 1;
            break;

      case USB_REQ_SET_INTERFACE:
            if (ctrl->bRequestType != (USB_DIR_OUT| USB_TYPE_STANDARD |
                        USB_RECIP_INTERFACE))
                  break;
            if (fsg->config && w_index == 0) {

                  /* Raise an exception to wipe out previous transaction
                   * state (queued bufs, etc) and install the new
                   * interface altsetting. */
                  raise_exception(fsg, FSG_STATE_INTERFACE_CHANGE);
                  value = DELAYED_STATUS;
            }
            break;
      case USB_REQ_GET_INTERFACE:
            if (ctrl->bRequestType != (USB_DIR_IN | USB_TYPE_STANDARD |
                        USB_RECIP_INTERFACE))
                  break;
            if (!fsg->config)
                  break;
            if (w_index != 0) {
                  value = -EDOM;
                  break;
            }
            VDBG(fsg, "get interface\n");
            *(u8 *) req->buf = 0;
            value = 1;
            break;

      default:
            VDBG(fsg,
                  "unknown control req %02x.%02x v%04x i%04x l%u\n",
                  ctrl->bRequestType, ctrl->bRequest,
                  w_value, w_index, le16_to_cpu(ctrl->wLength));
      }

      return value;
}


static int fsg_setup(struct usb_gadget *gadget,
            const struct usb_ctrlrequest *ctrl)
{
      struct fsg_dev          *fsg = get_gadget_data(gadget);
      int               rc;
      int               w_length = le16_to_cpu(ctrl->wLength);

      ++fsg->ep0_req_tag;           // Record arrival of a new request
      fsg->ep0req->context = NULL;
      fsg->ep0req->length = 0;
      dump_msg(fsg, "ep0-setup", (u8 *) ctrl, sizeof(*ctrl));

      if ((ctrl->bRequestType & USB_TYPE_MASK) == USB_TYPE_CLASS)
            rc = class_setup_req(fsg, ctrl);
      else
            rc = standard_setup_req(fsg, ctrl);

      /* Respond with data/status or defer until later? */
      if (rc >= 0 && rc != DELAYED_STATUS) {
            rc = min(rc, w_length);
            fsg->ep0req->length = rc;
            fsg->ep0req->zero = rc < w_length;
            fsg->ep0req_name = (ctrl->bRequestType & USB_DIR_IN ?
                        "ep0-in" : "ep0-out");
            rc = ep0_queue(fsg);
      }

      /* Device either stalls (rc < 0) or reports success */
      return rc;
}


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

/* All the following routines run in process context */


/* Use this for bulk or interrupt transfers, not ep0 */
static void start_transfer(struct fsg_dev *fsg, struct usb_ep *ep,
            struct usb_request *req, int *pbusy,
            enum fsg_buffer_state *state)
{
      int   rc;

      if (ep == fsg->bulk_in)
            dump_msg(fsg, "bulk-in", req->buf, req->length);
      else if (ep == fsg->intr_in)
            dump_msg(fsg, "intr-in", req->buf, req->length);

      spin_lock_irq(&fsg->lock);
      *pbusy = 1;
      *state = BUF_STATE_BUSY;
      spin_unlock_irq(&fsg->lock);
      rc = usb_ep_queue(ep, req, GFP_KERNEL);
      if (rc != 0) {
            *pbusy = 0;
            *state = BUF_STATE_EMPTY;

            /* We can't do much more than wait for a reset */

            /* Note: currently the net2280 driver fails zero-length
             * submissions if DMA is enabled. */
            if (rc != -ESHUTDOWN && !(rc == -EOPNOTSUPP &&
                                    req->length == 0))
                  WARNING(fsg, "error in submission: %s --> %d\n",
                              ep->name, rc);
      }
}


static int sleep_thread(struct fsg_dev *fsg)
{
      int   rc = 0;

      /* Wait until a signal arrives or we are woken up */
      for (;;) {
            try_to_freeze();
            set_current_state(TASK_INTERRUPTIBLE);
            if (signal_pending(current)) {
                  rc = -EINTR;
                  break;
            }
            if (fsg->thread_wakeup_needed)
                  break;
            schedule();
      }
      __set_current_state(TASK_RUNNING);
      fsg->thread_wakeup_needed = 0;
      return rc;
}


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

static int do_read(struct fsg_dev *fsg)
{
      struct lun        *curlun = fsg->curlun;
      u32               lba;
      struct fsg_buffhd *bh;
      int               rc;
      u32               amount_left;
      loff_t                  file_offset, file_offset_tmp;
      unsigned int            amount;
      unsigned int            partial_page;
      ssize_t                 nread;

      /* Get the starting Logical Block Address and check that it's
       * not too big */
      if (fsg->cmnd[0] == SC_READ_6)
            lba = get_unaligned_be24(&fsg->cmnd[1]);
      else {
            lba = get_unaligned_be32(&fsg->cmnd[2]);

            /* We allow DPO (Disable Page Out = don't save data in the
             * cache) and FUA (Force Unit Access = don't read from the
             * cache), but we don't implement them. */
            if ((fsg->cmnd[1] & ~0x18) != 0) {
                  curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
                  return -EINVAL;
            }
      }
      if (lba >= curlun->num_sectors) {
            curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
            return -EINVAL;
      }
      file_offset = ((loff_t) lba) << 9;

      /* Carry out the file reads */
      amount_left = fsg->data_size_from_cmnd;
      if (unlikely(amount_left == 0))
            return -EIO;            // No default reply

      for (;;) {

            /* Figure out how much we need to read:
             * Try to read the remaining amount.
             * But don't read more than the buffer size.
             * And don't try to read past the end of the file.
             * Finally, if we're not at a page boundary, don't read past
             *    the next page.
             * If this means reading 0 then we were asked to read past
             *    the end of file. */
            amount = min((unsigned int) amount_left, mod_data.buflen);
            amount = min((loff_t) amount,
                        curlun->file_length - file_offset);
            partial_page = file_offset & (PAGE_CACHE_SIZE - 1);
            if (partial_page > 0)
                  amount = min(amount, (unsigned int) PAGE_CACHE_SIZE -
                              partial_page);

            /* Wait for the next buffer to become available */
            bh = fsg->next_buffhd_to_fill;
            while (bh->state != BUF_STATE_EMPTY) {
                  rc = sleep_thread(fsg);
                  if (rc)
                        return rc;
            }

            /* If we were asked to read past the end of file,
             * end with an empty buffer. */
            if (amount == 0) {
                  curlun->sense_data =
                              SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
                  curlun->sense_data_info = file_offset >> 9;
                  curlun->info_valid = 1;
                  bh->inreq->length = 0;
                  bh->state = BUF_STATE_FULL;
                  break;
            }

            /* Perform the read */
            file_offset_tmp = file_offset;
            nread = vfs_read(curlun->filp,
                        (char __user *) bh->buf,
                        amount, &file_offset_tmp);
            VLDBG(curlun, "file read %u @ %llu -> %d\n", amount,
                        (unsigned long long) file_offset,
                        (int) nread);
            if (signal_pending(current))
                  return -EINTR;

            if (nread < 0) {
                  LDBG(curlun, "error in file read: %d\n",
                              (int) nread);
                  nread = 0;
            } else if (nread < amount) {
                  LDBG(curlun, "partial file read: %d/%u\n",
                              (int) nread, amount);
                  nread -= (nread & 511); // Round down to a block
            }
            file_offset  += nread;
            amount_left  -= nread;
            fsg->residue -= nread;
            bh->inreq->length = nread;
            bh->state = BUF_STATE_FULL;

            /* If an error occurred, report it and its position */
            if (nread < amount) {
                  curlun->sense_data = SS_UNRECOVERED_READ_ERROR;
                  curlun->sense_data_info = file_offset >> 9;
                  curlun->info_valid = 1;
                  break;
            }

            if (amount_left == 0)
                  break;            // No more left to read

            /* Send this buffer and go read some more */
            bh->inreq->zero = 0;
            start_transfer(fsg, fsg->bulk_in, bh->inreq,
                        &bh->inreq_busy, &bh->state);
            fsg->next_buffhd_to_fill = bh->next;
      }

      return -EIO;            // No default reply
}


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

static int do_write(struct fsg_dev *fsg)
{
      struct lun        *curlun = fsg->curlun;
      u32               lba;
      struct fsg_buffhd *bh;
      int               get_some_more;
      u32               amount_left_to_req, amount_left_to_write;
      loff_t                  usb_offset, file_offset, file_offset_tmp;
      unsigned int            amount;
      unsigned int            partial_page;
      ssize_t                 nwritten;
      int               rc;

      if (curlun->ro) {
            curlun->sense_data = SS_WRITE_PROTECTED;
            return -EINVAL;
      }
      spin_lock(&curlun->filp->f_lock);
      curlun->filp->f_flags &= ~O_SYNC;   // Default is not to wait
      spin_unlock(&curlun->filp->f_lock);

      /* Get the starting Logical Block Address and check that it's
       * not too big */
      if (fsg->cmnd[0] == SC_WRITE_6)
            lba = get_unaligned_be24(&fsg->cmnd[1]);
      else {
            lba = get_unaligned_be32(&fsg->cmnd[2]);

            /* We allow DPO (Disable Page Out = don't save data in the
             * cache) and FUA (Force Unit Access = write directly to the
             * medium).  We don't implement DPO; we implement FUA by
             * performing synchronous output. */
            if ((fsg->cmnd[1] & ~0x18) != 0) {
                  curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
                  return -EINVAL;
            }
            if (fsg->cmnd[1] & 0x08) {    // FUA
                  spin_lock(&curlun->filp->f_lock);
                  curlun->filp->f_flags |= O_SYNC;
                  spin_unlock(&curlun->filp->f_lock);
            }
      }
      if (lba >= curlun->num_sectors) {
            curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
            return -EINVAL;
      }

      /* Carry out the file writes */
      get_some_more = 1;
      file_offset = usb_offset = ((loff_t) lba) << 9;
      amount_left_to_req = amount_left_to_write = fsg->data_size_from_cmnd;

      while (amount_left_to_write > 0) {

            /* Queue a request for more data from the host */
            bh = fsg->next_buffhd_to_fill;
            if (bh->state == BUF_STATE_EMPTY && get_some_more) {

                  /* Figure out how much we want to get:
                   * Try to get the remaining amount.
                   * But don't get more than the buffer size.
                   * And don't try to go past the end of the file.
                   * If we're not at a page boundary,
                   *    don't go past the next page.
                   * If this means getting 0, then we were asked
                   *    to write past the end of file.
                   * Finally, round down to a block boundary. */
                  amount = min(amount_left_to_req, mod_data.buflen);
                  amount = min((loff_t) amount, curlun->file_length -
                              usb_offset);
                  partial_page = usb_offset & (PAGE_CACHE_SIZE - 1);
                  if (partial_page > 0)
                        amount = min(amount,
      (unsigned int) PAGE_CACHE_SIZE - partial_page);

                  if (amount == 0) {
                        get_some_more = 0;
                        curlun->sense_data =
                              SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
                        curlun->sense_data_info = usb_offset >> 9;
                        curlun->info_valid = 1;
                        continue;
                  }
                  amount -= (amount & 511);
                  if (amount == 0) {

                        /* Why were we were asked to transfer a
                         * partial block? */
                        get_some_more = 0;
                        continue;
                  }

                  /* Get the next buffer */
                  usb_offset += amount;
                  fsg->usb_amount_left -= amount;
                  amount_left_to_req -= amount;
                  if (amount_left_to_req == 0)
                        get_some_more = 0;

                  /* amount is always divisible by 512, hence by
                   * the bulk-out maxpacket size */
                  bh->outreq->length = bh->bulk_out_intended_length =
                              amount;
                  bh->outreq->short_not_ok = 1;
                  start_transfer(fsg, fsg->bulk_out, bh->outreq,
                              &bh->outreq_busy, &bh->state);
                  fsg->next_buffhd_to_fill = bh->next;
                  continue;
            }

            /* Write the received data to the backing file */
            bh = fsg->next_buffhd_to_drain;
            if (bh->state == BUF_STATE_EMPTY && !get_some_more)
                  break;                  // We stopped early
            if (bh->state == BUF_STATE_FULL) {
                  smp_rmb();
                  fsg->next_buffhd_to_drain = bh->next;
                  bh->state = BUF_STATE_EMPTY;

                  /* Did something go wrong with the transfer? */
                  if (bh->outreq->status != 0) {
                        curlun->sense_data = SS_COMMUNICATION_FAILURE;
                        curlun->sense_data_info = file_offset >> 9;
                        curlun->info_valid = 1;
                        break;
                  }

                  amount = bh->outreq->actual;
                  if (curlun->file_length - file_offset < amount) {
                        LERROR(curlun,
      "write %u @ %llu beyond end %llu\n",
      amount, (unsigned long long) file_offset,
      (unsigned long long) curlun->file_length);
                        amount = curlun->file_length - file_offset;
                  }

                  /* Perform the write */
                  file_offset_tmp = file_offset;
                  nwritten = vfs_write(curlun->filp,
                              (char __user *) bh->buf,
                              amount, &file_offset_tmp);
                  VLDBG(curlun, "file write %u @ %llu -> %d\n", amount,
                              (unsigned long long) file_offset,
                              (int) nwritten);
                  if (signal_pending(current))
                        return -EINTR;          // Interrupted!

                  if (nwritten < 0) {
                        LDBG(curlun, "error in file write: %d\n",
                                    (int) nwritten);
                        nwritten = 0;
                  } else if (nwritten < amount) {
                        LDBG(curlun, "partial file write: %d/%u\n",
                                    (int) nwritten, amount);
                        nwritten -= (nwritten & 511);
                                    // Round down to a block
                  }
                  file_offset += nwritten;
                  amount_left_to_write -= nwritten;
                  fsg->residue -= nwritten;

                  /* If an error occurred, report it and its position */
                  if (nwritten < amount) {
                        curlun->sense_data = SS_WRITE_ERROR;
                        curlun->sense_data_info = file_offset >> 9;
                        curlun->info_valid = 1;
                        break;
                  }

                  /* Did the host decide to stop early? */
                  if (bh->outreq->actual != bh->outreq->length) {
                        fsg->short_packet_received = 1;
                        break;
                  }
                  continue;
            }

            /* Wait for something to happen */
            rc = sleep_thread(fsg);
            if (rc)
                  return rc;
      }

      return -EIO;            // No default reply
}


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

/* Sync the file data, don't bother with the metadata.
 * This code was copied from fs/buffer.c:sys_fdatasync(). */
static int fsync_sub(struct lun *curlun)
{
      struct file *filp = curlun->filp;

      if (curlun->ro || !filp)
            return 0;
      return vfs_fsync(filp, filp->f_path.dentry, 1);
}

static void fsync_all(struct fsg_dev *fsg)
{
      int   i;

      for (i = 0; i < fsg->nluns; ++i)
            fsync_sub(&fsg->luns[i]);
}

static int do_synchronize_cache(struct fsg_dev *fsg)
{
      struct lun  *curlun = fsg->curlun;
      int         rc;

      /* We ignore the requested LBA and write out all file's
       * dirty data buffers. */
      rc = fsync_sub(curlun);
      if (rc)
            curlun->sense_data = SS_WRITE_ERROR;
      return 0;
}


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

static void invalidate_sub(struct lun *curlun)
{
      struct file *filp = curlun->filp;
      struct inode      *inode = filp->f_path.dentry->d_inode;
      unsigned long     rc;

      rc = invalidate_mapping_pages(inode->i_mapping, 0, -1);
      VLDBG(curlun, "invalidate_inode_pages -> %ld\n", rc);
}

static int do_verify(struct fsg_dev *fsg)
{
      struct lun        *curlun = fsg->curlun;
      u32               lba;
      u32               verification_length;
      struct fsg_buffhd *bh = fsg->next_buffhd_to_fill;
      loff_t                  file_offset, file_offset_tmp;
      u32               amount_left;
      unsigned int            amount;
      ssize_t                 nread;

      /* Get the starting Logical Block Address and check that it's
       * not too big */
      lba = get_unaligned_be32(&fsg->cmnd[2]);
      if (lba >= curlun->num_sectors) {
            curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
            return -EINVAL;
      }

      /* We allow DPO (Disable Page Out = don't save data in the
       * cache) but we don't implement it. */
      if ((fsg->cmnd[1] & ~0x10) != 0) {
            curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
            return -EINVAL;
      }

      verification_length = get_unaligned_be16(&fsg->cmnd[7]);
      if (unlikely(verification_length == 0))
            return -EIO;            // No default reply

      /* Prepare to carry out the file verify */
      amount_left = verification_length << 9;
      file_offset = ((loff_t) lba) << 9;

      /* Write out all the dirty buffers before invalidating them */
      fsync_sub(curlun);
      if (signal_pending(current))
            return -EINTR;

      invalidate_sub(curlun);
      if (signal_pending(current))
            return -EINTR;

      /* Just try to read the requested blocks */
      while (amount_left > 0) {

            /* Figure out how much we need to read:
             * Try to read the remaining amount, but not more than
             * the buffer size.
             * And don't try to read past the end of the file.
             * If this means reading 0 then we were asked to read
             * past the end of file. */
            amount = min((unsigned int) amount_left, mod_data.buflen);
            amount = min((loff_t) amount,
                        curlun->file_length - file_offset);
            if (amount == 0) {
                  curlun->sense_data =
                              SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
                  curlun->sense_data_info = file_offset >> 9;
                  curlun->info_valid = 1;
                  break;
            }

            /* Perform the read */
            file_offset_tmp = file_offset;
            nread = vfs_read(curlun->filp,
                        (char __user *) bh->buf,
                        amount, &file_offset_tmp);
            VLDBG(curlun, "file read %u @ %llu -> %d\n", amount,
                        (unsigned long long) file_offset,
                        (int) nread);
            if (signal_pending(current))
                  return -EINTR;

            if (nread < 0) {
                  LDBG(curlun, "error in file verify: %d\n",
                              (int) nread);
                  nread = 0;
            } else if (nread < amount) {
                  LDBG(curlun, "partial file verify: %d/%u\n",
                              (int) nread, amount);
                  nread -= (nread & 511); // Round down to a sector
            }
            if (nread == 0) {
                  curlun->sense_data = SS_UNRECOVERED_READ_ERROR;
                  curlun->sense_data_info = file_offset >> 9;
                  curlun->info_valid = 1;
                  break;
            }
            file_offset += nread;
            amount_left -= nread;
      }
      return 0;
}


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

static int do_inquiry(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
      u8    *buf = (u8 *) bh->buf;

      static char vendor_id[] = "Linux   ";
      static char product_disk_id[] = "File-Stor Gadget";
      static char product_cdrom_id[] = "File-CD Gadget  ";

      if (!fsg->curlun) {           // Unsupported LUNs are okay
            fsg->bad_lun_okay = 1;
            memset(buf, 0, 36);
            buf[0] = 0x7f;          // Unsupported, no device-type
            buf[4] = 31;            // Additional length
            return 36;
      }

      memset(buf, 0, 8);
      buf[0] = (mod_data.cdrom ? TYPE_CDROM : TYPE_DISK);
      if (mod_data.removable)
            buf[1] = 0x80;
      buf[2] = 2;       // ANSI SCSI level 2
      buf[3] = 2;       // SCSI-2 INQUIRY data format
      buf[4] = 31;            // Additional length
                        // No special options
      sprintf(buf + 8, "%-8s%-16s%04x", vendor_id,
                  (mod_data.cdrom ? product_cdrom_id :
                        product_disk_id),
                  mod_data.release);
      return 36;
}


static int do_request_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
      struct lun  *curlun = fsg->curlun;
      u8          *buf = (u8 *) bh->buf;
      u32         sd, sdinfo;
      int         valid;

      /*
       * From the SCSI-2 spec., section 7.9 (Unit attention condition):
       *
       * If a REQUEST SENSE command is received from an initiator
       * with a pending unit attention condition (before the target
       * generates the contingent allegiance condition), then the
       * target shall either:
       *   a) report any pending sense data and preserve the unit
       *    attention condition on the logical unit, or,
       *   b) report the unit attention condition, may discard any
       *    pending sense data, and clear the unit attention
       *    condition on the logical unit for that initiator.
       *
       * FSG normally uses option a); enable this code to use option b).
       */
#if 0
      if (curlun && curlun->unit_attention_data != SS_NO_SENSE) {
            curlun->sense_data = curlun->unit_attention_data;
            curlun->unit_attention_data = SS_NO_SENSE;
      }
#endif

      if (!curlun) {          // Unsupported LUNs are okay
            fsg->bad_lun_okay = 1;
            sd = SS_LOGICAL_UNIT_NOT_SUPPORTED;
            sdinfo = 0;
            valid = 0;
      } else {
            sd = curlun->sense_data;
            sdinfo = curlun->sense_data_info;
            valid = curlun->info_valid << 7;
            curlun->sense_data = SS_NO_SENSE;
            curlun->sense_data_info = 0;
            curlun->info_valid = 0;
      }

      memset(buf, 0, 18);
      buf[0] = valid | 0x70;              // Valid, current error
      buf[2] = SK(sd);
      put_unaligned_be32(sdinfo, &buf[3]);      /* Sense information */
      buf[7] = 18 - 8;              // Additional sense length
      buf[12] = ASC(sd);
      buf[13] = ASCQ(sd);
      return 18;
}


static int do_read_capacity(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
      struct lun  *curlun = fsg->curlun;
      u32         lba = get_unaligned_be32(&fsg->cmnd[2]);
      int         pmi = fsg->cmnd[8];
      u8          *buf = (u8 *) bh->buf;

      /* Check the PMI and LBA fields */
      if (pmi > 1 || (pmi == 0 && lba != 0)) {
            curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
            return -EINVAL;
      }

      put_unaligned_be32(curlun->num_sectors - 1, &buf[0]);
                                    /* Max logical block */
      put_unaligned_be32(512, &buf[4]);   /* Block length */
      return 8;
}


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);
      }
}

static int do_read_header(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
      struct lun  *curlun = fsg->curlun;
      int         msf = fsg->cmnd[1] & 0x02;
      u32         lba = get_unaligned_be32(&fsg->cmnd[2]);
      u8          *buf = (u8 *) bh->buf;

      if ((fsg->cmnd[1] & ~0x02) != 0) {        /* Mask away MSF */
            curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
            return -EINVAL;
      }
      if (lba >= curlun->num_sectors) {
            curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
            return -EINVAL;
      }

      memset(buf, 0, 8);
      buf[0] = 0x01;          /* 2048 bytes of user data, rest is EC */
      store_cdrom_address(&buf[4], msf, lba);
      return 8;
}


static int do_read_toc(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
      struct lun  *curlun = fsg->curlun;
      int         msf = fsg->cmnd[1] & 0x02;
      int         start_track = fsg->cmnd[6];
      u8          *buf = (u8 *) bh->buf;

      if ((fsg->cmnd[1] & ~0x02) != 0 ||        /* Mask away MSF */
                  start_track > 1) {
            curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
            return -EINVAL;
      }

      memset(buf, 0, 20);
      buf[1] = (20-2);        /* TOC data length */
      buf[2] = 1;             /* First track number */
      buf[3] = 1;             /* Last track number */
      buf[5] = 0x16;                /* Data track, copying allowed */
      buf[6] = 0x01;                /* Only track is number 1 */
      store_cdrom_address(&buf[8], msf, 0);

      buf[13] = 0x16;               /* Lead-out track is data */
      buf[14] = 0xAA;               /* Lead-out track number */
      store_cdrom_address(&buf[16], msf, curlun->num_sectors);
      return 20;
}


static int do_mode_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
      struct lun  *curlun = fsg->curlun;
      int         mscmnd = fsg->cmnd[0];
      u8          *buf = (u8 *) bh->buf;
      u8          *buf0 = buf;
      int         pc, page_code;
      int         changeable_values, all_pages;
      int         valid_page = 0;
      int         len, limit;

      if ((fsg->cmnd[1] & ~0x08) != 0) {        // Mask away DBD
            curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
            return -EINVAL;
      }
      pc = fsg->cmnd[2] >> 6;
      page_code = fsg->cmnd[2] & 0x3f;
      if (pc == 3) {
            curlun->sense_data = SS_SAVING_PARAMETERS_NOT_SUPPORTED;
            return -EINVAL;
      }
      changeable_values = (pc == 1);
      all_pages = (page_code == 0x3f);

      /* Write the mode parameter header.  Fixed values are: default
       * medium type, no cache control (DPOFUA), and no block descriptors.
       * The only variable value is the WriteProtect bit.  We will fill in
       * the mode data length later. */
      memset(buf, 0, 8);
      if (mscmnd == SC_MODE_SENSE_6) {
            buf[2] = (curlun->ro ? 0x80 : 0x00);            // WP, DPOFUA
            buf += 4;
            limit = 255;
      } else {                // SC_MODE_SENSE_10
            buf[3] = (curlun->ro ? 0x80 : 0x00);            // WP, DPOFUA
            buf += 8;
            limit = 65535;          // Should really be mod_data.buflen
      }

      /* No block descriptors */

      /* The mode pages, in numerical order.  The only page we support
       * is the Caching page. */
      if (page_code == 0x08 || all_pages) {
            valid_page = 1;
            buf[0] = 0x08;          // Page code
            buf[1] = 10;            // Page length
            memset(buf+2, 0, 10);   // None of the fields are changeable

            if (!changeable_values) {
                  buf[2] = 0x04;    // Write cache enable,
                              // Read cache not disabled
                              // No cache retention priorities
                  put_unaligned_be16(0xffff, &buf[4]);
                              /* Don't disable prefetch */
                              /* Minimum prefetch = 0 */
                  put_unaligned_be16(0xffff, &buf[8]);
                              /* Maximum prefetch */
                  put_unaligned_be16(0xffff, &buf[10]);
                              /* Maximum prefetch ceiling */
            }
            buf += 12;
      }

      /* Check that a valid page was requested and the mode data length
       * isn't too long. */
      len = buf - buf0;
      if (!valid_page || len > limit) {
            curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
            return -EINVAL;
      }

      /*  Store the mode data length */
      if (mscmnd == SC_MODE_SENSE_6)
            buf0[0] = len - 1;
      else
            put_unaligned_be16(len - 2, buf0);
      return len;
}


static int do_start_stop(struct fsg_dev *fsg)
{
      struct lun  *curlun = fsg->curlun;
      int         loej, start;

      if (!mod_data.removable) {
            curlun->sense_data = SS_INVALID_COMMAND;
            return -EINVAL;
      }

      // int immed = fsg->cmnd[1] & 0x01;
      loej = fsg->cmnd[4] & 0x02;
      start = fsg->cmnd[4] & 0x01;

#ifdef CONFIG_USB_FILE_STORAGE_TEST
      if ((fsg->cmnd[1] & ~0x01) != 0 ||        // Mask away Immed
                  (fsg->cmnd[4] & ~0x03) != 0) {      // Mask LoEj, Start
            curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
            return -EINVAL;
      }

      if (!start) {

            /* Are we allowed to unload the media? */
            if (curlun->prevent_medium_removal) {
                  LDBG(curlun, "unload attempt prevented\n");
                  curlun->sense_data = SS_MEDIUM_REMOVAL_PREVENTED;
                  return -EINVAL;
            }
            if (loej) {       // Simulate an unload/eject
                  up_read(&fsg->filesem);
                  down_write(&fsg->filesem);
                  close_backing_file(curlun);
                  up_write(&fsg->filesem);
                  down_read(&fsg->filesem);
            }
      } else {

            /* Our emulation doesn't support mounting; the medium is
             * available for use as soon as it is loaded. */
            if (!backing_file_is_open(curlun)) {
                  curlun->sense_data = SS_MEDIUM_NOT_PRESENT;
                  return -EINVAL;
            }
      }
#endif
      return 0;
}


static int do_prevent_allow(struct fsg_dev *fsg)
{
      struct lun  *curlun = fsg->curlun;
      int         prevent;

      if (!mod_data.removable) {
            curlun->sense_data = SS_INVALID_COMMAND;
            return -EINVAL;
      }

      prevent = fsg->cmnd[4] & 0x01;
      if ((fsg->cmnd[4] & ~0x01) != 0) {        // Mask away Prevent
            curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
            return -EINVAL;
      }

      if (curlun->prevent_medium_removal && !prevent)
            fsync_sub(curlun);
      curlun->prevent_medium_removal = prevent;
      return 0;
}


static int do_read_format_capacities(struct fsg_dev *fsg,
                  struct fsg_buffhd *bh)
{
      struct lun  *curlun = fsg->curlun;
      u8          *buf = (u8 *) bh->buf;

      buf[0] = buf[1] = buf[2] = 0;
      buf[3] = 8;       // Only the Current/Maximum Capacity Descriptor
      buf += 4;

      put_unaligned_be32(curlun->num_sectors, &buf[0]);
                                    /* Number of blocks */
      put_unaligned_be32(512, &buf[4]);   /* Block length */
      buf[4] = 0x02;                      /* Current capacity */
      return 12;
}


static int do_mode_select(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
      struct lun  *curlun = fsg->curlun;

      /* We don't support MODE SELECT */
      curlun->sense_data = SS_INVALID_COMMAND;
      return -EINVAL;
}


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

static int halt_bulk_in_endpoint(struct fsg_dev *fsg)
{
      int   rc;

      rc = fsg_set_halt(fsg, fsg->bulk_in);
      if (rc == -EAGAIN)
            VDBG(fsg, "delayed bulk-in endpoint halt\n");
      while (rc != 0) {
            if (rc != -EAGAIN) {
                  WARNING(fsg, "usb_ep_set_halt -> %d\n", rc);
                  rc = 0;
                  break;
            }

            /* Wait for a short time and then try again */
            if (msleep_interruptible(100) != 0)
                  return -EINTR;
            rc = usb_ep_set_halt(fsg->bulk_in);
      }
      return rc;
}

static int wedge_bulk_in_endpoint(struct fsg_dev *fsg)
{
      int   rc;

      DBG(fsg, "bulk-in set wedge\n");
      rc = usb_ep_set_wedge(fsg->bulk_in);
      if (rc == -EAGAIN)
            VDBG(fsg, "delayed bulk-in endpoint wedge\n");
      while (rc != 0) {
            if (rc != -EAGAIN) {
                  WARNING(fsg, "usb_ep_set_wedge -> %d\n", rc);
                  rc = 0;
                  break;
            }

            /* Wait for a short time and then try again */
            if (msleep_interruptible(100) != 0)
                  return -EINTR;
            rc = usb_ep_set_wedge(fsg->bulk_in);
      }
      return rc;
}

static int pad_with_zeros(struct fsg_dev *fsg)
{
      struct fsg_buffhd *bh = fsg->next_buffhd_to_fill;
      u32               nkeep = bh->inreq->length;
      u32               nsend;
      int               rc;

      bh->state = BUF_STATE_EMPTY;        // For the first iteration
      fsg->usb_amount_left = nkeep + fsg->residue;
      while (fsg->usb_amount_left > 0) {

            /* Wait for the next buffer to be free */
            while (bh->state != BUF_STATE_EMPTY) {
                  rc = sleep_thread(fsg);
                  if (rc)
                        return rc;
            }

            nsend = min(fsg->usb_amount_left, (u32) mod_data.buflen);
            memset(bh->buf + nkeep, 0, nsend - nkeep);
            bh->inreq->length = nsend;
            bh->inreq->zero = 0;
            start_transfer(fsg, fsg->bulk_in, bh->inreq,
                        &bh->inreq_busy, &bh->state);
            bh = fsg->next_buffhd_to_fill = bh->next;
            fsg->usb_amount_left -= nsend;
            nkeep = 0;
      }
      return 0;
}

static int throw_away_data(struct fsg_dev *fsg)
{
      struct fsg_buffhd *bh;
      u32               amount;
      int               rc;

      while ((bh = fsg->next_buffhd_to_drain)->state != BUF_STATE_EMPTY ||
                  fsg->usb_amount_left > 0) {

            /* Throw away the data in a filled buffer */
            if (bh->state == BUF_STATE_FULL) {
                  smp_rmb();
                  bh->state = BUF_STATE_EMPTY;
                  fsg->next_buffhd_to_drain = bh->next;

                  /* A short packet or an error ends everything */
                  if (bh->outreq->actual != bh->outreq->length ||
                              bh->outreq->status != 0) {
                        raise_exception(fsg, FSG_STATE_ABORT_BULK_OUT);
                        return -EINTR;
                  }
                  continue;
            }

            /* Try to submit another request if we need one */
            bh = fsg->next_buffhd_to_fill;
            if (bh->state == BUF_STATE_EMPTY && fsg->usb_amount_left > 0) {
                  amount = min(fsg->usb_amount_left,
                              (u32) mod_data.buflen);

                  /* amount is always divisible by 512, hence by
                   * the bulk-out maxpacket size */
                  bh->outreq->length = bh->bulk_out_intended_length =
                              amount;
                  bh->outreq->short_not_ok = 1;
                  start_transfer(fsg, fsg->bulk_out, bh->outreq,
                              &bh->outreq_busy, &bh->state);
                  fsg->next_buffhd_to_fill = bh->next;
                  fsg->usb_amount_left -= amount;
                  continue;
            }

            /* Otherwise wait for something to happen */
            rc = sleep_thread(fsg);
            if (rc)
                  return rc;
      }
      return 0;
}


static int finish_reply(struct fsg_dev *fsg)
{
      struct fsg_buffhd *bh = fsg->next_buffhd_to_fill;
      int               rc = 0;

      switch (fsg->data_dir) {
      case DATA_DIR_NONE:
            break;                  // Nothing to send

      /* If we don't know whether the host wants to read or write,
       * this must be CB or CBI with an unknown command.  We mustn't
       * try to send or receive any data.  So stall both bulk pipes
       * if we can and wait for a reset. */
      case DATA_DIR_UNKNOWN:
            if (mod_data.can_stall) {
                  fsg_set_halt(fsg, fsg->bulk_out);
                  rc = halt_bulk_in_endpoint(fsg);
            }
            break;

      /* All but the last buffer of data must have already been sent */
      case DATA_DIR_TO_HOST:
            if (fsg->data_size == 0)
                  ;           // Nothing to send

            /* If there's no residue, simply send the last buffer */
            else if (fsg->residue == 0) {
                  bh->inreq->zero = 0;
                  start_transfer(fsg, fsg->bulk_in, bh->inreq,
                              &bh->inreq_busy, &bh->state);
                  fsg->next_buffhd_to_fill = bh->next;
            }

            /* There is a residue.  For CB and CBI, simply mark the end
             * of the data with a short packet.  However, if we are
             * allowed to stall, there was no data at all (residue ==
             * data_size), and the command failed (invalid LUN or
             * sense data is set), then halt the bulk-in endpoint
             * instead. */
            else if (!transport_is_bbb()) {
                  if (mod_data.can_stall &&
                              fsg->residue == fsg->data_size &&
      (!fsg->curlun || fsg->curlun->sense_data != SS_NO_SENSE)) {
                        bh->state = BUF_STATE_EMPTY;
                        rc = halt_bulk_in_endpoint(fsg);
                  } else {
                        bh->inreq->zero = 1;
                        start_transfer(fsg, fsg->bulk_in, bh->inreq,
                                    &bh->inreq_busy, &bh->state);
                        fsg->next_buffhd_to_fill = bh->next;
                  }
            }

            /* For Bulk-only, if we're allowed to stall then send the
             * short packet and halt the bulk-in endpoint.  If we can't
             * stall, pad out the remaining data with 0's. */
            else {
                  if (mod_data.can_stall) {
                        bh->inreq->zero = 1;
                        start_transfer(fsg, fsg->bulk_in, bh->inreq,
                                    &bh->inreq_busy, &bh->state);
                        fsg->next_buffhd_to_fill = bh->next;
                        rc = halt_bulk_in_endpoint(fsg);
                  } else
                        rc = pad_with_zeros(fsg);
            }
            break;

      /* We have processed all we want from the data the host has sent.
       * There may still be outstanding bulk-out requests. */
      case DATA_DIR_FROM_HOST:
            if (fsg->residue == 0)
                  ;           // Nothing to receive

            /* Did the host stop sending unexpectedly early? */
            else if (fsg->short_packet_received) {
                  raise_exception(fsg, FSG_STATE_ABORT_BULK_OUT);
                  rc = -EINTR;
            }

            /* We haven't processed all the incoming data.  Even though
             * we may be allowed to stall, doing so would cause a race.
             * The controller may already have ACK'ed all the remaining
             * bulk-out packets, in which case the host wouldn't see a
             * STALL.  Not realizing the endpoint was halted, it wouldn't
             * clear the halt -- leading to problems later on. */
#if 0
            else if (mod_data.can_stall) {
                  fsg_set_halt(fsg, fsg->bulk_out);
                  raise_exception(fsg, FSG_STATE_ABORT_BULK_OUT);
                  rc = -EINTR;
            }
#endif

            /* We can't stall.  Read in the excess data and throw it
             * all away. */
            else
                  rc = throw_away_data(fsg);
            break;
      }
      return rc;
}


static int send_status(struct fsg_dev *fsg)
{
      struct lun        *curlun = fsg->curlun;
      struct fsg_buffhd *bh;
      int               rc;
      u8                status = USB_STATUS_PASS;
      u32               sd, sdinfo = 0;

      /* Wait for the next buffer to become available */
      bh = fsg->next_buffhd_to_fill;
      while (bh->state != BUF_STATE_EMPTY) {
            rc = sleep_thread(fsg);
            if (rc)
                  return rc;
      }

      if (curlun) {
            sd = curlun->sense_data;
            sdinfo = curlun->sense_data_info;
      } else if (fsg->bad_lun_okay)
            sd = SS_NO_SENSE;
      else
            sd = SS_LOGICAL_UNIT_NOT_SUPPORTED;

      if (fsg->phase_error) {
            DBG(fsg, "sending phase-error status\n");
            status = USB_STATUS_PHASE_ERROR;
            sd = SS_INVALID_COMMAND;
      } else if (sd != SS_NO_SENSE) {
            DBG(fsg, "sending command-failure status\n");
            status = USB_STATUS_FAIL;
            VDBG(fsg, "  sense data: SK x%02x, ASC x%02x, ASCQ x%02x;"
                        "  info x%x\n",
                        SK(sd), ASC(sd), ASCQ(sd), sdinfo);
      }

      if (transport_is_bbb()) {
            struct bulk_cs_wrap     *csw = bh->buf;

            /* Store and send the Bulk-only CSW */
            csw->Signature = cpu_to_le32(USB_BULK_CS_SIG);
            csw->Tag = fsg->tag;
            csw->Residue = cpu_to_le32(fsg->residue);
            csw->Status = status;

            bh->inreq->length = USB_BULK_CS_WRAP_LEN;
            bh->inreq->zero = 0;
            start_transfer(fsg, fsg->bulk_in, bh->inreq,
                        &bh->inreq_busy, &bh->state);

      } else if (mod_data.transport_type == USB_PR_CB) {

            /* Control-Bulk transport has no status phase! */
            return 0;

      } else {                // USB_PR_CBI
            struct interrupt_data   *buf = bh->buf;

            /* Store and send the Interrupt data.  UFI sends the ASC
             * and ASCQ bytes.  Everything else sends a Type (which
             * is always 0) and the status Value. */
            if (mod_data.protocol_type == USB_SC_UFI) {
                  buf->bType = ASC(sd);
                  buf->bValue = ASCQ(sd);
            } else {
                  buf->bType = 0;
                  buf->bValue = status;
            }
            fsg->intreq->length = CBI_INTERRUPT_DATA_LEN;

            fsg->intr_buffhd = bh;        // Point to the right buffhd
            fsg->intreq->buf = bh->inreq->buf;
            fsg->intreq->context = bh;
            start_transfer(fsg, fsg->intr_in, fsg->intreq,
                        &fsg->intreq_busy, &bh->state);
      }

      fsg->next_buffhd_to_fill = bh->next;
      return 0;
}


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

/* Check whether the command is properly formed and whether its data size
 * and direction agree with the values we already have. */
static int check_command(struct fsg_dev *fsg, int cmnd_size,
            enum data_direction data_dir, unsigned int mask,
            int needs_medium, const char *name)
{
      int               i;
      int               lun = fsg->cmnd[1] >> 5;
      static const char dirletter[4] = {'u', 'o', 'i', 'n'};
      char              hdlen[20];
      struct lun        *curlun;

      /* Adjust the expected cmnd_size for protocol encapsulation padding.
       * Transparent SCSI doesn't pad. */
      if (protocol_is_scsi())
            ;

      /* There's some disagreement as to whether RBC pads commands or not.
       * We'll play it safe and accept either form. */
      else if (mod_data.protocol_type == USB_SC_RBC) {
            if (fsg->cmnd_size == 12)
                  cmnd_size = 12;

      /* All the other protocols pad to 12 bytes */
      } else
            cmnd_size = 12;

      hdlen[0] = 0;
      if (fsg->data_dir != DATA_DIR_UNKNOWN)
            sprintf(hdlen, ", H%c=%u", dirletter[(int) fsg->data_dir],
                        fsg->data_size);
      VDBG(fsg, "SCSI command: %s;  Dc=%d, D%c=%u;  Hc=%d%s\n",
                  name, cmnd_size, dirletter[(int) data_dir],
                  fsg->data_size_from_cmnd, fsg->cmnd_size, hdlen);

      /* We can't reply at all until we know the correct data direction
       * and size. */
      if (fsg->data_size_from_cmnd == 0)
            data_dir = DATA_DIR_NONE;
      if (fsg->data_dir == DATA_DIR_UNKNOWN) {  // CB or CBI
            fsg->data_dir = data_dir;
            fsg->data_size = fsg->data_size_from_cmnd;

      } else {                            // Bulk-only
            if (fsg->data_size < fsg->data_size_from_cmnd) {

                  /* Host data size < Device data size is a phase error.
                   * Carry out the command, but only transfer as much
                   * as we are allowed. */
                  fsg->data_size_from_cmnd = fsg->data_size;
                  fsg->phase_error = 1;
            }
      }
      fsg->residue = fsg->usb_amount_left = fsg->data_size;

      /* Conflicting data directions is a phase error */
      if (fsg->data_dir != data_dir && fsg->data_size_from_cmnd > 0) {
            fsg->phase_error = 1;
            return -EINVAL;
      }

      /* Verify the length of the command itself */
      if (cmnd_size != fsg->cmnd_size) {

            /* Special case workaround: There are plenty of buggy SCSI
             * implementations. Many have issues with cbw->Length
             * field passing a wrong command size. For those cases we
             * always try to work around the problem by using the length
             * sent by the host side provided it is at least as large
             * as the correct command length.
             * Examples of such cases would be MS-Windows, which issues
             * REQUEST SENSE with cbw->Length == 12 where it should
             * be 6, and xbox360 issuing INQUIRY, TEST UNIT READY and
             * REQUEST SENSE with cbw->Length == 10 where it should
             * be 6 as well.
             */
            if (cmnd_size <= fsg->cmnd_size) {
                  DBG(fsg, "%s is buggy! Expected length %d "
                              "but we got %d\n", name,
                              cmnd_size, fsg->cmnd_size);
                  cmnd_size = fsg->cmnd_size;
            } else {
                  fsg->phase_error = 1;
                  return -EINVAL;
            }
      }

      /* Check that the LUN values are consistent */
      if (transport_is_bbb()) {
            if (fsg->lun != lun)
                  DBG(fsg, "using LUN %d from CBW, "
                              "not LUN %d from CDB\n",
                              fsg->lun, lun);
      } else
            fsg->lun = lun;         // Use LUN from the command

      /* Check the LUN */
      if (fsg->lun >= 0 && fsg->lun < fsg->nluns) {
            fsg->curlun = curlun = &fsg->luns[fsg->lun];
            if (fsg->cmnd[0] != SC_REQUEST_SENSE) {
                  curlun->sense_data = SS_NO_SENSE;
                  curlun->sense_data_info = 0;
                  curlun->info_valid = 0;
            }
      } else {
            fsg->curlun = curlun = NULL;
            fsg->bad_lun_okay = 0;

            /* INQUIRY and REQUEST SENSE commands are explicitly allowed
             * to use unsupported LUNs; all others may not. */
            if (fsg->cmnd[0] != SC_INQUIRY &&
                        fsg->cmnd[0] != SC_REQUEST_SENSE) {
                  DBG(fsg, "unsupported LUN %d\n", fsg->lun);
                  return -EINVAL;
            }
      }

      /* If a unit attention condition exists, only INQUIRY and
       * REQUEST SENSE commands are allowed; anything else must fail. */
      if (curlun && curlun->unit_attention_data != SS_NO_SENSE &&
                  fsg->cmnd[0] != SC_INQUIRY &&
                  fsg->cmnd[0] != SC_REQUEST_SENSE) {
            curlun->sense_data = curlun->unit_attention_data;
            curlun->unit_attention_data = SS_NO_SENSE;
            return -EINVAL;
      }

      /* Check that only command bytes listed in the mask are non-zero */
      fsg->cmnd[1] &= 0x1f;               // Mask away the LUN
      for (i = 1; i < cmnd_size; ++i) {
            if (fsg->cmnd[i] && !(mask & (1 << i))) {
                  if (curlun)
                        curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
                  return -EINVAL;
            }
      }

      /* If the medium isn't mounted and the command needs to access
       * it, return an error. */
      if (curlun && !backing_file_is_open(curlun) && needs_medium) {
            curlun->sense_data = SS_MEDIUM_NOT_PRESENT;
            return -EINVAL;
      }

      return 0;
}


static int do_scsi_command(struct fsg_dev *fsg)
{
      struct fsg_buffhd *bh;
      int               rc;
      int               reply = -EINVAL;
      int               i;
      static char       unknown[16];

      dump_cdb(fsg);

      /* Wait for the next buffer to become available for data or status */
      bh = fsg->next_buffhd_to_drain = fsg->next_buffhd_to_fill;
      while (bh->state != BUF_STATE_EMPTY) {
            rc = sleep_thread(fsg);
            if (rc)
                  return rc;
      }
      fsg->phase_error = 0;
      fsg->short_packet_received = 0;

      down_read(&fsg->filesem);     // We're using the backing file
      switch (fsg->cmnd[0]) {

      case SC_INQUIRY:
            fsg->data_size_from_cmnd = fsg->cmnd[4];
            if ((reply = check_command(fsg, 6, DATA_DIR_TO_HOST,
                        (1<<4), 0,
                        "INQUIRY")) == 0)
                  reply = do_inquiry(fsg, bh);
            break;

      case SC_MODE_SELECT_6:
            fsg->data_size_from_cmnd = fsg->cmnd[4];
            if ((reply = check_command(fsg, 6, DATA_DIR_FROM_HOST,
                        (1<<1) | (1<<4), 0,
                        "MODE SELECT(6)")) == 0)
                  reply = do_mode_select(fsg, bh);
            break;

      case SC_MODE_SELECT_10:
            fsg->data_size_from_cmnd = get_unaligned_be16(&fsg->cmnd[7]);
            if ((reply = check_command(fsg, 10, DATA_DIR_FROM_HOST,
                        (1<<1) | (3<<7), 0,
                        "MODE SELECT(10)")) == 0)
                  reply = do_mode_select(fsg, bh);
            break;

      case SC_MODE_SENSE_6:
            fsg->data_size_from_cmnd = fsg->cmnd[4];
            if ((reply = check_command(fsg, 6, DATA_DIR_TO_HOST,
                        (1<<1) | (1<<2) | (1<<4), 0,
                        "MODE SENSE(6)")) == 0)
                  reply = do_mode_sense(fsg, bh);
            break;

      case SC_MODE_SENSE_10:
            fsg->data_size_from_cmnd = get_unaligned_be16(&fsg->cmnd[7]);
            if ((reply = check_command(fsg, 10, DATA_DIR_TO_HOST,
                        (1<<1) | (1<<2) | (3<<7), 0,
                        "MODE SENSE(10)")) == 0)
                  reply = do_mode_sense(fsg, bh);
            break;

      case SC_PREVENT_ALLOW_MEDIUM_REMOVAL:
            fsg->data_size_from_cmnd = 0;
            if ((reply = check_command(fsg, 6, DATA_DIR_NONE,
                        (1<<4), 0,
                        "PREVENT-ALLOW MEDIUM REMOVAL")) == 0)
                  reply = do_prevent_allow(fsg);
            break;

      case SC_READ_6:
            i = fsg->cmnd[4];
            fsg->data_size_from_cmnd = (i == 0 ? 256 : i) << 9;
            if ((reply = check_command(fsg, 6, DATA_DIR_TO_HOST,
                        (7<<1) | (1<<4), 1,
                        "READ(6)")) == 0)
                  reply = do_read(fsg);
            break;

      case SC_READ_10:
            fsg->data_size_from_cmnd =
                        get_unaligned_be16(&fsg->cmnd[7]) << 9;
            if ((reply = check_command(fsg, 10, DATA_DIR_TO_HOST,
                        (1<<1) | (0xf<<2) | (3<<7), 1,
                        "READ(10)")) == 0)
                  reply = do_read(fsg);
            break;

      case SC_READ_12:
            fsg->data_size_from_cmnd =
                        get_unaligned_be32(&fsg->cmnd[6]) << 9;
            if ((reply = check_command(fsg, 12, DATA_DIR_TO_HOST,
                        (1<<1) | (0xf<<2) | (0xf<<6), 1,
                        "READ(12)")) == 0)
                  reply = do_read(fsg);
            break;

      case SC_READ_CAPACITY:
            fsg->data_size_from_cmnd = 8;
            if ((reply = check_command(fsg, 10, DATA_DIR_TO_HOST,
                        (0xf<<2) | (1<<8), 1,
                        "READ CAPACITY")) == 0)
                  reply = do_read_capacity(fsg, bh);
            break;

      case SC_READ_HEADER:
            if (!mod_data.cdrom)
                  goto unknown_cmnd;
            fsg->data_size_from_cmnd = get_unaligned_be16(&fsg->cmnd[7]);
            if ((reply = check_command(fsg, 10, DATA_DIR_TO_HOST,
                        (3<<7) | (0x1f<<1), 1,
                        "READ HEADER")) == 0)
                  reply = do_read_header(fsg, bh);
            break;

      case SC_READ_TOC:
            if (!mod_data.cdrom)
                  goto unknown_cmnd;
            fsg->data_size_from_cmnd = get_unaligned_be16(&fsg->cmnd[7]);
            if ((reply = check_command(fsg, 10, DATA_DIR_TO_HOST,
                        (7<<6) | (1<<1), 1,
                        "READ TOC")) == 0)
                  reply = do_read_toc(fsg, bh);
            break;

      case SC_READ_FORMAT_CAPACITIES:
            fsg->data_size_from_cmnd = get_unaligned_be16(&fsg->cmnd[7]);
            if ((reply = check_command(fsg, 10, DATA_DIR_TO_HOST,
                        (3<<7), 1,
                        "READ FORMAT CAPACITIES")) == 0)
                  reply = do_read_format_capacities(fsg, bh);
            break;

      case SC_REQUEST_SENSE:
            fsg->data_size_from_cmnd = fsg->cmnd[4];
            if ((reply = check_command(fsg, 6, DATA_DIR_TO_HOST,
                        (1<<4), 0,
                        "REQUEST SENSE")) == 0)
                  reply = do_request_sense(fsg, bh);
            break;

      case SC_START_STOP_UNIT:
            fsg->data_size_from_cmnd = 0;
            if ((reply = check_command(fsg, 6, DATA_DIR_NONE,
                        (1<<1) | (1<<4), 0,
                        "START-STOP UNIT")) == 0)
                  reply = do_start_stop(fsg);
            break;

      case SC_SYNCHRONIZE_CACHE:
            fsg->data_size_from_cmnd = 0;
            if ((reply = check_command(fsg, 10, DATA_DIR_NONE,
                        (0xf<<2) | (3<<7), 1,
                        "SYNCHRONIZE CACHE")) == 0)
                  reply = do_synchronize_cache(fsg);
            break;

      case SC_TEST_UNIT_READY:
            fsg->data_size_from_cmnd = 0;
            reply = check_command(fsg, 6, DATA_DIR_NONE,
                        0, 1,
                        "TEST UNIT READY");
            break;

      /* Although optional, this command is used by MS-Windows.  We
       * support a minimal version: BytChk must be 0. */
      case SC_VERIFY:
            fsg->data_size_from_cmnd = 0;
            if ((reply = check_command(fsg, 10, DATA_DIR_NONE,
                        (1<<1) | (0xf<<2) | (3<<7), 1,
                        "VERIFY")) == 0)
                  reply = do_verify(fsg);
            break;

      case SC_WRITE_6:
            i = fsg->cmnd[4];
            fsg->data_size_from_cmnd = (i == 0 ? 256 : i) << 9;
            if ((reply = check_command(fsg, 6, DATA_DIR_FROM_HOST,
                        (7<<1) | (1<<4), 1,
                        "WRITE(6)")) == 0)
                  reply = do_write(fsg);
            break;

      case SC_WRITE_10:
            fsg->data_size_from_cmnd =
                        get_unaligned_be16(&fsg->cmnd[7]) << 9;
            if ((reply = check_command(fsg, 10, DATA_DIR_FROM_HOST,
                        (1<<1) | (0xf<<2) | (3<<7), 1,
                        "WRITE(10)")) == 0)
                  reply = do_write(fsg);
            break;

      case SC_WRITE_12:
            fsg->data_size_from_cmnd =
                        get_unaligned_be32(&fsg->cmnd[6]) << 9;
            if ((reply = check_command(fsg, 12, DATA_DIR_FROM_HOST,
                        (1<<1) | (0xf<<2) | (0xf<<6), 1,
                        "WRITE(12)")) == 0)
                  reply = do_write(fsg);
            break;

      /* Some mandatory commands that we recognize but don't implement.
       * They don't mean much in this setting.  It's left as an exercise
       * for anyone interested to implement RESERVE and RELEASE in terms
       * of Posix locks. */
      case SC_FORMAT_UNIT:
      case SC_RELEASE:
      case SC_RESERVE:
      case SC_SEND_DIAGNOSTIC:
            // Fall through

      default:
 unknown_cmnd:
            fsg->data_size_from_cmnd = 0;
            sprintf(unknown, "Unknown x%02x", fsg->cmnd[0]);
            if ((reply = check_command(fsg, fsg->cmnd_size,
                        DATA_DIR_UNKNOWN, 0xff, 0, unknown)) == 0) {
                  fsg->curlun->sense_data = SS_INVALID_COMMAND;
                  reply = -EINVAL;
            }
            break;
      }
      up_read(&fsg->filesem);

      if (reply == -EINTR || signal_pending(current))
            return -EINTR;

      /* Set up the single reply buffer for finish_reply() */
      if (reply == -EINVAL)
            reply = 0;        // Error reply length
      if (reply >= 0 && fsg->data_dir == DATA_DIR_TO_HOST) {
            reply = min((u32) reply, fsg->data_size_from_cmnd);
            bh->inreq->length = reply;
            bh->state = BUF_STATE_FULL;
            fsg->residue -= reply;
      }                       // Otherwise it's already set

      return 0;
}


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

static int received_cbw(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
      struct usb_request      *req = bh->outreq;
      struct bulk_cb_wrap     *cbw = req->buf;

      /* Was this a real packet?  Should it be ignored? */
      if (req->status || test_bit(IGNORE_BULK_OUT, &fsg->atomic_bitflags))
            return -EINVAL;

      /* Is the CBW valid? */
      if (req->actual != USB_BULK_CB_WRAP_LEN ||
                  cbw->Signature != cpu_to_le32(
                        USB_BULK_CB_SIG)) {
            DBG(fsg, "invalid CBW: len %u sig 0x%x\n",
                        req->actual,
                        le32_to_cpu(cbw->Signature));

            /* The Bulk-only spec says we MUST stall the IN endpoint
             * (6.6.1), so it's unavoidable.  It also says we must
             * retain this state until the next reset, but there's
             * no way to tell the controller driver it should ignore
             * Clear-Feature(HALT) requests.
             *
             * We aren't required to halt the OUT endpoint; instead
             * we can simply accept and discard any data received
             * until the next reset. */
            wedge_bulk_in_endpoint(fsg);
            set_bit(IGNORE_BULK_OUT, &fsg->atomic_bitflags);
            return -EINVAL;
      }

      /* Is the CBW meaningful? */
      if (cbw->Lun >= MAX_LUNS || cbw->Flags & ~USB_BULK_IN_FLAG ||
                  cbw->Length <= 0 || cbw->Length > MAX_COMMAND_SIZE) {
            DBG(fsg, "non-meaningful CBW: lun = %u, flags = 0x%x, "
                        "cmdlen %u\n",
                        cbw->Lun, cbw->Flags, cbw->Length);

            /* We can do anything we want here, so let's stall the
             * bulk pipes if we are allowed to. */
            if (mod_data.can_stall) {
                  fsg_set_halt(fsg, fsg->bulk_out);
                  halt_bulk_in_endpoint(fsg);
            }
            return -EINVAL;
      }

      /* Save the command for later */
      fsg->cmnd_size = cbw->Length;
      memcpy(fsg->cmnd, cbw->CDB, fsg->cmnd_size);
      if (cbw->Flags & USB_BULK_IN_FLAG)
            fsg->data_dir = DATA_DIR_TO_HOST;
      else
            fsg->data_dir = DATA_DIR_FROM_HOST;
      fsg->data_size = le32_to_cpu(cbw->DataTransferLength);
      if (fsg->data_size == 0)
            fsg->data_dir = DATA_DIR_NONE;
      fsg->lun = cbw->Lun;
      fsg->tag = cbw->Tag;
      return 0;
}


static int get_next_command(struct fsg_dev *fsg)
{
      struct fsg_buffhd *bh;
      int               rc = 0;

      if (transport_is_bbb()) {

            /* Wait for the next buffer to become available */
            bh = fsg->next_buffhd_to_fill;
            while (bh->state != BUF_STATE_EMPTY) {
                  rc = sleep_thread(fsg);
                  if (rc)
                        return rc;
            }

            /* Queue a request to read a Bulk-only CBW */
            set_bulk_out_req_length(fsg, bh, USB_BULK_CB_WRAP_LEN);
            bh->outreq->short_not_ok = 1;
            start_transfer(fsg, fsg->bulk_out, bh->outreq,
                        &bh->outreq_busy, &bh->state);

            /* We will drain the buffer in software, which means we
             * can reuse it for the next filling.  No need to advance
             * next_buffhd_to_fill. */

            /* Wait for the CBW to arrive */
            while (bh->state != BUF_STATE_FULL) {
                  rc = sleep_thread(fsg);
                  if (rc)
                        return rc;
            }
            smp_rmb();
            rc = received_cbw(fsg, bh);
            bh->state = BUF_STATE_EMPTY;

      } else {          // USB_PR_CB or USB_PR_CBI

            /* Wait for the next command to arrive */
            while (fsg->cbbuf_cmnd_size == 0) {
                  rc = sleep_thread(fsg);
                  if (rc)
                        return rc;
            }

            /* Is the previous status interrupt request still busy?
             * The host is allowed to skip reading the status,
             * so we must cancel it. */
            if (fsg->intreq_busy)
                  usb_ep_dequeue(fsg->intr_in, fsg->intreq);

            /* Copy the command and mark the buffer empty */
            fsg->data_dir = DATA_DIR_UNKNOWN;
            spin_lock_irq(&fsg->lock);
            fsg->cmnd_size = fsg->cbbuf_cmnd_size;
            memcpy(fsg->cmnd, fsg->cbbuf_cmnd, fsg->cmnd_size);
            fsg->cbbuf_cmnd_size = 0;
            spin_unlock_irq(&fsg->lock);
      }
      return rc;
}


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

static int enable_endpoint(struct fsg_dev *fsg, struct usb_ep *ep,
            const struct usb_endpoint_descriptor *d)
{
      int   rc;

      ep->driver_data = fsg;
      rc = usb_ep_enable(ep, d);
      if (rc)
            ERROR(fsg, "can't enable %s, result %d\n", ep->name, rc);
      return rc;
}

static int alloc_request(struct fsg_dev *fsg, struct usb_ep *ep,
            struct usb_request **preq)
{
      *preq = usb_ep_alloc_request(ep, GFP_ATOMIC);
      if (*preq)
            return 0;
      ERROR(fsg, "can't allocate request for %s\n", ep->name);
      return -ENOMEM;
}

/*
 * Reset interface setting and re-init endpoint state (toggle etc).
 * Call with altsetting < 0 to disable the interface.  The only other
 * available altsetting is 0, which enables the interface.
 */
static int do_set_interface(struct fsg_dev *fsg, int altsetting)
{
      int   rc = 0;
      int   i;
      const struct usb_endpoint_descriptor      *d;

      if (fsg->running)
            DBG(fsg, "reset interface\n");

reset:
      /* Deallocate the requests */
      for (i = 0; i < NUM_BUFFERS; ++i) {
            struct fsg_buffhd *bh = &fsg->buffhds[i];

            if (bh->inreq) {
                  usb_ep_free_request(fsg->bulk_in, bh->inreq);
                  bh->inreq = NULL;
            }
            if (bh->outreq) {
                  usb_ep_free_request(fsg->bulk_out, bh->outreq);
                  bh->outreq = NULL;
            }
      }
      if (fsg->intreq) {
            usb_ep_free_request(fsg->intr_in, fsg->intreq);
            fsg->intreq = NULL;
      }

      /* Disable the endpoints */
      if (fsg->bulk_in_enabled) {
            usb_ep_disable(fsg->bulk_in);
            fsg->bulk_in_enabled = 0;
      }
      if (fsg->bulk_out_enabled) {
            usb_ep_disable(fsg->bulk_out);
            fsg->bulk_out_enabled = 0;
      }
      if (fsg->intr_in_enabled) {
            usb_ep_disable(fsg->intr_in);
            fsg->intr_in_enabled = 0;
      }

      fsg->running = 0;
      if (altsetting < 0 || rc != 0)
            return rc;

      DBG(fsg, "set interface %d\n", altsetting);

      /* Enable the endpoints */
      d = ep_desc(fsg->gadget, &fs_bulk_in_desc, &hs_bulk_in_desc);
      if ((rc = enable_endpoint(fsg, fsg->bulk_in, d)) != 0)
            goto reset;
      fsg->bulk_in_enabled = 1;

      d = ep_desc(fsg->gadget, &fs_bulk_out_desc, &hs_bulk_out_desc);
      if ((rc = enable_endpoint(fsg, fsg->bulk_out, d)) != 0)
            goto reset;
      fsg->bulk_out_enabled = 1;
      fsg->bulk_out_maxpacket = le16_to_cpu(d->wMaxPacketSize);
      clear_bit(IGNORE_BULK_OUT, &fsg->atomic_bitflags);

      if (transport_is_cbi()) {
            d = ep_desc(fsg->gadget, &fs_intr_in_desc, &hs_intr_in_desc);
            if ((rc = enable_endpoint(fsg, fsg->intr_in, d)) != 0)
                  goto reset;
            fsg->intr_in_enabled = 1;
      }

      /* Allocate the requests */
      for (i = 0; i < NUM_BUFFERS; ++i) {
            struct fsg_buffhd *bh = &fsg->buffhds[i];

            if ((rc = alloc_request(fsg, fsg->bulk_in, &bh->inreq)) != 0)
                  goto reset;
            if ((rc = alloc_request(fsg, fsg->bulk_out, &bh->outreq)) != 0)
                  goto reset;
            bh->inreq->buf = bh->outreq->buf = bh->buf;
            bh->inreq->context = bh->outreq->context = bh;
            bh->inreq->complete = bulk_in_complete;
            bh->outreq->complete = bulk_out_complete;
      }
      if (transport_is_cbi()) {
            if ((rc = alloc_request(fsg, fsg->intr_in, &fsg->intreq)) != 0)
                  goto reset;
            fsg->intreq->complete = intr_in_complete;
      }

      fsg->running = 1;
      for (i = 0; i < fsg->nluns; ++i)
            fsg->luns[i].unit_attention_data = SS_RESET_OCCURRED;
      return rc;
}


/*
 * Change our operational configuration.  This code must agree with the code
 * that returns config descriptors, and with interface altsetting code.
 *
 * It's also responsible for power management interactions.  Some
 * configurations might not work with our current power sources.
 * For now we just assume the gadget is always self-powered.
 */
static int do_set_config(struct fsg_dev *fsg, u8 new_config)
{
      int   rc = 0;

      /* Disable the single interface */
      if (fsg->config != 0) {
            DBG(fsg, "reset config\n");
            fsg->config = 0;
            rc = do_set_interface(fsg, -1);
      }

      /* Enable the interface */
      if (new_config != 0) {
            fsg->config = new_config;
            if ((rc = do_set_interface(fsg, 0)) != 0)
                  fsg->config = 0;  // Reset on errors
            else {
                  char *speed;

                  switch (fsg->gadget->speed) {
                  case USB_SPEED_LOW:     speed = "low";    break;
                  case USB_SPEED_FULL:    speed = "full";   break;
                  case USB_SPEED_HIGH:    speed = "high";   break;
                  default:          speed = "?";      break;
                  }
                  INFO(fsg, "%s speed config #%d\n", speed, fsg->config);
            }
      }
      return rc;
}


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

static void handle_exception(struct fsg_dev *fsg)
{
      siginfo_t         info;
      int               sig;
      int               i;
      int               num_active;
      struct fsg_buffhd *bh;
      enum fsg_state          old_state;
      u8                new_config;
      struct lun        *curlun;
      unsigned int            exception_req_tag;
      int               rc;

      /* Clear the existing signals.  Anything but SIGUSR1 is converted
       * into a high-priority EXIT exception. */
      for (;;) {
            sig = dequeue_signal_lock(current, &current->blocked, &info);
            if (!sig)
                  break;
            if (sig != SIGUSR1) {
                  if (fsg->state < FSG_STATE_EXIT)
                        DBG(fsg, "Main thread exiting on signal\n");
                  raise_exception(fsg, FSG_STATE_EXIT);
            }
      }

      /* Cancel all the pending transfers */
      if (fsg->intreq_busy)
            usb_ep_dequeue(fsg->intr_in, fsg->intreq);
      for (i = 0; i < NUM_BUFFERS; ++i) {
            bh = &fsg->buffhds[i];
            if (bh->inreq_busy)
                  usb_ep_dequeue(fsg->bulk_in, bh->inreq);
            if (bh->outreq_busy)
                  usb_ep_dequeue(fsg->bulk_out, bh->outreq);
      }

      /* Wait until everything is idle */
      for (;;) {
            num_active = fsg->intreq_busy;
            for (i = 0; i < NUM_BUFFERS; ++i) {
                  bh = &fsg->buffhds[i];
                  num_active += bh->inreq_busy + bh->outreq_busy;
            }
            if (num_active == 0)
                  break;
            if (sleep_thread(fsg))
                  return;
      }

      /* Clear out the controller's fifos */
      if (fsg->bulk_in_enabled)
            usb_ep_fifo_flush(fsg->bulk_in);
      if (fsg->bulk_out_enabled)
            usb_ep_fifo_flush(fsg->bulk_out);
      if (fsg->intr_in_enabled)
            usb_ep_fifo_flush(fsg->intr_in);

      /* Reset the I/O buffer states and pointers, the SCSI
       * state, and the exception.  Then invoke the handler. */
      spin_lock_irq(&fsg->lock);

      for (i = 0; i < NUM_BUFFERS; ++i) {
            bh = &fsg->buffhds[i];
            bh->state = BUF_STATE_EMPTY;
      }
      fsg->next_buffhd_to_fill = fsg->next_buffhd_to_drain =
                  &fsg->buffhds[0];

      exception_req_tag = fsg->exception_req_tag;
      new_config = fsg->new_config;
      old_state = fsg->state;

      if (old_state == FSG_STATE_ABORT_BULK_OUT)
            fsg->state = FSG_STATE_STATUS_PHASE;
      else {
            for (i = 0; i < fsg->nluns; ++i) {
                  curlun = &fsg->luns[i];
                  curlun->prevent_medium_removal = 0;
                  curlun->sense_data = curlun->unit_attention_data =
                              SS_NO_SENSE;
                  curlun->sense_data_info = 0;
                  curlun->info_valid = 0;
            }
            fsg->state = FSG_STATE_IDLE;
      }
      spin_unlock_irq(&fsg->lock);

      /* Carry out any extra actions required for the exception */
      switch (old_state) {
      default:
            break;

      case FSG_STATE_ABORT_BULK_OUT:
            send_status(fsg);
            spin_lock_irq(&fsg->lock);
            if (fsg->state == FSG_STATE_STATUS_PHASE)
                  fsg->state = FSG_STATE_IDLE;
            spin_unlock_irq(&fsg->lock);
            break;

      case FSG_STATE_RESET:
            /* In case we were forced against our will to halt a
             * bulk endpoint, clear the halt now.  (The SuperH UDC
             * requires this.) */
            if (test_and_clear_bit(IGNORE_BULK_OUT, &fsg->atomic_bitflags))
                  usb_ep_clear_halt(fsg->bulk_in);

            if (transport_is_bbb()) {
                  if (fsg->ep0_req_tag == exception_req_tag)
                        ep0_queue(fsg);   // Complete the status stage

            } else if (transport_is_cbi())
                  send_status(fsg); // Status by interrupt pipe

            /* Technically this should go here, but it would only be
             * a waste of time.  Ditto for the INTERFACE_CHANGE and
             * CONFIG_CHANGE cases. */
            // for (i = 0; i < fsg->nluns; ++i)
            //    fsg->luns[i].unit_attention_data = SS_RESET_OCCURRED;
            break;

      case FSG_STATE_INTERFACE_CHANGE:
            rc = do_set_interface(fsg, 0);
            if (fsg->ep0_req_tag != exception_req_tag)
                  break;
            if (rc != 0)                  // STALL on errors
                  fsg_set_halt(fsg, fsg->ep0);
            else                    // Complete the status stage
                  ep0_queue(fsg);
            break;

      case FSG_STATE_CONFIG_CHANGE:
            rc = do_set_config(fsg, new_config);
            if (fsg->ep0_req_tag != exception_req_tag)
                  break;
            if (rc != 0)                  // STALL on errors
                  fsg_set_halt(fsg, fsg->ep0);
            else                    // Complete the status stage
                  ep0_queue(fsg);
            break;

      case FSG_STATE_DISCONNECT:
            fsync_all(fsg);
            do_set_config(fsg, 0);        // Unconfigured state
            break;

      case FSG_STATE_EXIT:
      case FSG_STATE_TERMINATED:
            do_set_config(fsg, 0);              // Free resources
            spin_lock_irq(&fsg->lock);
            fsg->state = FSG_STATE_TERMINATED;  // Stop the thread
            spin_unlock_irq(&fsg->lock);
            break;
      }
}


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

static int fsg_main_thread(void *fsg_)
{
      struct fsg_dev          *fsg = fsg_;

      /* Allow the thread to be killed by a signal, but set the signal mask
       * to block everything but INT, TERM, KILL, and USR1. */
      allow_signal(SIGINT);
      allow_signal(SIGTERM);
      allow_signal(SIGKILL);
      allow_signal(SIGUSR1);

      /* Allow the thread to be frozen */
      set_freezable();

      /* Arrange for userspace references to be interpreted as kernel
       * pointers.  That way we can pass a kernel pointer to a routine
       * that expects a __user pointer and it will work okay. */
      set_fs(get_ds());

      /* The main loop */
      while (fsg->state != FSG_STATE_TERMINATED) {
            if (exception_in_progress(fsg) || signal_pending(current)) {
                  handle_exception(fsg);
                  continue;
            }

            if (!fsg->running) {
                  sleep_thread(fsg);
                  continue;
            }

            if (get_next_command(fsg))
                  continue;

            spin_lock_irq(&fsg->lock);
            if (!exception_in_progress(fsg))
                  fsg->state = FSG_STATE_DATA_PHASE;
            spin_unlock_irq(&fsg->lock);

            if (do_scsi_command(fsg) || finish_reply(fsg))
                  continue;

            spin_lock_irq(&fsg->lock);
            if (!exception_in_progress(fsg))
                  fsg->state = FSG_STATE_STATUS_PHASE;
            spin_unlock_irq(&fsg->lock);

            if (send_status(fsg))
                  continue;

            spin_lock_irq(&fsg->lock);
            if (!exception_in_progress(fsg))
                  fsg->state = FSG_STATE_IDLE;
            spin_unlock_irq(&fsg->lock);
            }

      spin_lock_irq(&fsg->lock);
      fsg->thread_task = NULL;
      spin_unlock_irq(&fsg->lock);

      /* If we are exiting because of a signal, unregister the
       * gadget driver. */
      if (test_and_clear_bit(REGISTERED, &fsg->atomic_bitflags))
            usb_gadget_unregister_driver(&fsg_driver);

      /* Let the unbind and cleanup routines know the thread has exited */
      complete_and_exit(&fsg->thread_notifier, 0);
}


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

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

static int open_backing_file(struct lun *curlun, const char *filename)
{
      int                     ro;
      struct file             *filp = NULL;
      int                     rc = -EINVAL;
      struct inode                  *inode = NULL;
      loff_t                        size;
      loff_t                        num_sectors;
      loff_t                        min_sectors;

      /* R/W if we can, R/O if we must */
      ro = curlun->ro;
      if (!ro) {
            filp = filp_open(filename, O_RDWR | O_LARGEFILE, 0);
            if (-EROFS == PTR_ERR(filp))
                  ro = 1;
      }
      if (ro)
            filp = filp_open(filename, O_RDONLY | O_LARGEFILE, 0);
      if (IS_ERR(filp)) {
            LINFO(curlun, "unable to open backing file: %s\n", filename);
            return PTR_ERR(filp);
      }

      if (!(filp->f_mode & FMODE_WRITE))
            ro = 1;

      if (filp->f_path.dentry)
            inode = filp->f_path.dentry->d_inode;
      if (inode && S_ISBLK(inode->i_mode)) {
            if (bdev_read_only(inode->i_bdev))
                  ro = 1;
      } else if (!inode || !S_ISREG(inode->i_mode)) {
            LINFO(curlun, "invalid file type: %s\n", filename);
            goto out;
      }

      /* If we can't read the file, it's no good.
       * If we can't write the file, use it read-only. */
      if (!filp->f_op || !(filp->f_op->read || filp->f_op->aio_read)) {
            LINFO(curlun, "file not readable: %s\n", filename);
            goto out;
      }
      if (!(filp->f_op->write || filp->f_op->aio_write))
            ro = 1;

      size = i_size_read(inode->i_mapping->host);
      if (size < 0) {
            LINFO(curlun, "unable to find file size: %s\n", filename);
            rc = (int) size;
            goto out;
      }
      num_sectors = size >> 9;      // File size in 512-byte blocks
      min_sectors = 1;
      if (mod_data.cdrom) {
            num_sectors &= ~3;      // Reduce to a multiple of 2048
            min_sectors = 300*4;    // Smallest track is 300 frames
            if (num_sectors >= 256*60*75*4) {
                  num_sectors = (256*60*75 - 1) * 4;
                  LINFO(curlun, "file too big: %s\n", filename);
                  LINFO(curlun, "using only first %d blocks\n",
                              (int) num_sectors);
            }
      }
      if (num_sectors < min_sectors) {
            LINFO(curlun, "file too small: %s\n", filename);
            rc = -ETOOSMALL;
            goto out;
      }

      get_file(filp);
      curlun->ro = ro;
      curlun->filp = filp;
      curlun->file_length = size;
      curlun->num_sectors = num_sectors;
      LDBG(curlun, "open backing file: %s\n", filename);
      rc = 0;

out:
      filp_close(filp, current->files);
      return rc;
}


static void close_backing_file(struct lun *curlun)
{
      if (curlun->filp) {
            LDBG(curlun, "close backing file\n");
            fput(curlun->filp);
            curlun->filp = NULL;
      }
}


static ssize_t show_ro(struct device *dev, struct device_attribute *attr, char *buf)
{
      struct lun  *curlun = dev_to_lun(dev);

      return sprintf(buf, "%d\n", curlun->ro);
}

static ssize_t show_file(struct device *dev, struct device_attribute *attr,
            char *buf)
{
      struct lun  *curlun = dev_to_lun(dev);
      struct fsg_dev    *fsg = dev_get_drvdata(dev);
      char        *p;
      ssize_t           rc;

      down_read(&fsg->filesem);
      if (backing_file_is_open(curlun)) { // Get the complete pathname
            p = d_path(&curlun->filp->f_path, buf, PAGE_SIZE - 1);
            if (IS_ERR(p))
                  rc = PTR_ERR(p);
            else {
                  rc = strlen(p);
                  memmove(buf, p, rc);
                  buf[rc] = '\n';         // Add a newline
                  buf[++rc] = 0;
            }
      } else {                      // No file, return 0 bytes
            *buf = 0;
            rc = 0;
      }
      up_read(&fsg->filesem);
      return rc;
}


static ssize_t store_ro(struct device *dev, struct device_attribute *attr,
            const char *buf, size_t count)
{
      ssize_t           rc = count;
      struct lun  *curlun = dev_to_lun(dev);
      struct fsg_dev    *fsg = dev_get_drvdata(dev);
      int         i;

      if (sscanf(buf, "%d", &i) != 1)
            return -EINVAL;

      /* Allow the write-enable status to change only while the backing file
       * is closed. */
      down_read(&fsg->filesem);
      if (backing_file_is_open(curlun)) {
            LDBG(curlun, "read-only status change prevented\n");
            rc = -EBUSY;
      } else {
            curlun->ro = !!i;
            LDBG(curlun, "read-only status set to %d\n", curlun->ro);
      }
      up_read(&fsg->filesem);
      return rc;
}

static ssize_t store_file(struct device *dev, struct device_attribute *attr,
            const char *buf, size_t count)
{
      struct lun  *curlun = dev_to_lun(dev);
      struct fsg_dev    *fsg = dev_get_drvdata(dev);
      int         rc = 0;

      if (curlun->prevent_medium_removal && backing_file_is_open(curlun)) {
            LDBG(curlun, "eject attempt prevented\n");
            return -EBUSY;                      // "Door is locked"
      }

      /* Remove a trailing newline */
      if (count > 0 && buf[count-1] == '\n')
            ((char *) buf)[count-1] = 0;        // Ugh!

      /* Eject current medium */
      down_write(&fsg->filesem);
      if (backing_file_is_open(curlun)) {
            close_backing_file(curlun);
            curlun->unit_attention_data = SS_MEDIUM_NOT_PRESENT;
      }

      /* Load new medium */
      if (count > 0 && buf[0]) {
            rc = open_backing_file(curlun, buf);
            if (rc == 0)
                  curlun->unit_attention_data =
                              SS_NOT_READY_TO_READY_TRANSITION;
      }
      up_write(&fsg->filesem);
      return (rc < 0 ? rc : count);
}


/* The write permissions and store_xxx pointers are set in fsg_bind() */
static DEVICE_ATTR(ro, 0444, show_ro, NULL);
static DEVICE_ATTR(file, 0444, show_file, NULL);


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

static void fsg_release(struct kref *ref)
{
      struct fsg_dev    *fsg = container_of(ref, struct fsg_dev, ref);

      kfree(fsg->luns);
      kfree(fsg);
}

static void lun_release(struct device *dev)
{
      struct fsg_dev    *fsg = dev_get_drvdata(dev);

      kref_put(&fsg->ref, fsg_release);
}

static void /* __init_or_exit */ fsg_unbind(struct usb_gadget *gadget)
{
      struct fsg_dev          *fsg = get_gadget_data(gadget);
      int               i;
      struct lun        *curlun;
      struct usb_request      *req = fsg->ep0req;

      DBG(fsg, "unbind\n");
      clear_bit(REGISTERED, &fsg->atomic_bitflags);

      /* Unregister the sysfs attribute files and the LUNs */
      for (i = 0; i < fsg->nluns; ++i) {
            curlun = &fsg->luns[i];
            if (curlun->registered) {
                  device_remove_file(&curlun->dev, &dev_attr_ro);
                  device_remove_file(&curlun->dev, &dev_attr_file);
                  close_backing_file(curlun);
                  device_unregister(&curlun->dev);
                  curlun->registered = 0;
            }
      }

      /* If the thread isn't already dead, tell it to exit now */
      if (fsg->state != FSG_STATE_TERMINATED) {
            raise_exception(fsg, FSG_STATE_EXIT);
            wait_for_completion(&fsg->thread_notifier);

            /* The cleanup routine waits for this completion also */
            complete(&fsg->thread_notifier);
      }

      /* Free the data buffers */
      for (i = 0; i < NUM_BUFFERS; ++i)
            kfree(fsg->buffhds[i].buf);

      /* Free the request and buffer for endpoint 0 */
      if (req) {
            kfree(req->buf);
            usb_ep_free_request(fsg->ep0, req);
      }

      set_gadget_data(gadget, NULL);
}


static int __init check_parameters(struct fsg_dev *fsg)
{
      int   prot;
      int   gcnum;

      /* Store the default values */
      mod_data.transport_type = USB_PR_BULK;
      mod_data.transport_name = "Bulk-only";
      mod_data.protocol_type = USB_SC_SCSI;
      mod_data.protocol_name = "Transparent SCSI";

      /* Some peripheral controllers are known not to be able to
       * halt bulk endpoints correctly.  If one of them is present,
       * disable stalls.
       */
      if (gadget_is_sh(fsg->gadget) || gadget_is_at91(fsg->gadget))
            mod_data.can_stall = 0;

      if (mod_data.release == 0xffff) {   // Parameter wasn't set
            /* The sa1100 controller is not supported */
            if (gadget_is_sa1100(fsg->gadget))
                  gcnum = -1;
            else
                  gcnum = usb_gadget_controller_number(fsg->gadget);
            if (gcnum >= 0)
                  mod_data.release = 0x0300 + gcnum;
            else {
                  WARNING(fsg, "controller '%s' not recognized\n",
                        fsg->gadget->name);
                  mod_data.release = 0x0399;
            }
      }

      prot = simple_strtol(mod_data.protocol_parm, NULL, 0);

#ifdef CONFIG_USB_FILE_STORAGE_TEST
      if (strnicmp(mod_data.transport_parm, "BBB", 10) == 0) {
            ;           // Use default setting
      } else if (strnicmp(mod_data.transport_parm, "CB", 10) == 0) {
            mod_data.transport_type = USB_PR_CB;
            mod_data.transport_name = "Control-Bulk";
      } else if (strnicmp(mod_data.transport_parm, "CBI", 10) == 0) {
            mod_data.transport_type = USB_PR_CBI;
            mod_data.transport_name = "Control-Bulk-Interrupt";
      } else {
            ERROR(fsg, "invalid transport: %s\n", mod_data.transport_parm);
            return -EINVAL;
      }

      if (strnicmp(mod_data.protocol_parm, "SCSI", 10) == 0 ||
                  prot == USB_SC_SCSI) {
            ;           // Use default setting
      } else if (strnicmp(mod_data.protocol_parm, "RBC", 10) == 0 ||
                  prot == USB_SC_RBC) {
            mod_data.protocol_type = USB_SC_RBC;
            mod_data.protocol_name = "RBC";
      } else if (strnicmp(mod_data.protocol_parm, "8020", 4) == 0 ||
                  strnicmp(mod_data.protocol_parm, "ATAPI", 10) == 0 ||
                  prot == USB_SC_8020) {
            mod_data.protocol_type = USB_SC_8020;
            mod_data.protocol_name = "8020i (ATAPI)";
      } else if (strnicmp(mod_data.protocol_parm, "QIC", 3) == 0 ||
                  prot == USB_SC_QIC) {
            mod_data.protocol_type = USB_SC_QIC;
            mod_data.protocol_name = "QIC-157";
      } else if (strnicmp(mod_data.protocol_parm, "UFI", 10) == 0 ||
                  prot == USB_SC_UFI) {
            mod_data.protocol_type = USB_SC_UFI;
            mod_data.protocol_name = "UFI";
      } else if (strnicmp(mod_data.protocol_parm, "8070", 4) == 0 ||
                  prot == USB_SC_8070) {
            mod_data.protocol_type = USB_SC_8070;
            mod_data.protocol_name = "8070i";
      } else {
            ERROR(fsg, "invalid protocol: %s\n", mod_data.protocol_parm);
            return -EINVAL;
      }

      mod_data.buflen &= PAGE_CACHE_MASK;
      if (mod_data.buflen <= 0) {
            ERROR(fsg, "invalid buflen\n");
            return -ETOOSMALL;
      }
#endif /* CONFIG_USB_FILE_STORAGE_TEST */

      return 0;
}


static int __init fsg_bind(struct usb_gadget *gadget)
{
      struct fsg_dev          *fsg = the_fsg;
      int               rc;
      int               i;
      struct lun        *curlun;
      struct usb_ep           *ep;
      struct usb_request      *req;
      char              *pathbuf, *p;

      fsg->gadget = gadget;
      set_gadget_data(gadget, fsg);
      fsg->ep0 = gadget->ep0;
      fsg->ep0->driver_data = fsg;

      if ((rc = check_parameters(fsg)) != 0)
            goto out;

      if (mod_data.removable) {     // Enable the store_xxx attributes
            dev_attr_file.attr.mode = 0644;
            dev_attr_file.store = store_file;
            if (!mod_data.cdrom) {
                  dev_attr_ro.attr.mode = 0644;
                  dev_attr_ro.store = store_ro;
            }
      }

      /* Find out how many LUNs there should be */
      i = mod_data.nluns;
      if (i == 0)
            i = max(mod_data.num_filenames, 1u);
      if (i > MAX_LUNS) {
            ERROR(fsg, "invalid number of LUNs: %d\n", i);
            rc = -EINVAL;
            goto out;
      }

      /* Create the LUNs, open their backing files, and register the
       * LUN devices in sysfs. */
      fsg->luns = kzalloc(i * sizeof(struct lun), GFP_KERNEL);
      if (!fsg->luns) {
            rc = -ENOMEM;
            goto out;
      }
      fsg->nluns = i;

      for (i = 0; i < fsg->nluns; ++i) {
            curlun = &fsg->luns[i];
            curlun->ro = mod_data.ro[i];
            if (mod_data.cdrom)
                  curlun->ro = 1;
            curlun->dev.release = lun_release;
            curlun->dev.parent = &gadget->dev;
            curlun->dev.driver = &fsg_driver.driver;
            dev_set_drvdata(&curlun->dev, fsg);
            dev_set_name(&curlun->dev,"%s-lun%d",
                       dev_name(&gadget->dev), i);

            if ((rc = device_register(&curlun->dev)) != 0) {
                  INFO(fsg, "failed to register LUN%d: %d\n", i, rc);
                  goto out;
            }
            if ((rc = device_create_file(&curlun->dev,
                              &dev_attr_ro)) != 0 ||
                        (rc = device_create_file(&curlun->dev,
                              &dev_attr_file)) != 0) {
                  device_unregister(&curlun->dev);
                  goto out;
            }
            curlun->registered = 1;
            kref_get(&fsg->ref);

            if (mod_data.file[i] && *mod_data.file[i]) {
                  if ((rc = open_backing_file(curlun,
                              mod_data.file[i])) != 0)
                        goto out;
            } else if (!mod_data.removable) {
                  ERROR(fsg, "no file given for LUN%d\n", i);
                  rc = -EINVAL;
                  goto out;
            }
      }

      /* Find all the endpoints we will use */
      usb_ep_autoconfig_reset(gadget);
      ep = usb_ep_autoconfig(gadget, &fs_bulk_in_desc);
      if (!ep)
            goto autoconf_fail;
      ep->driver_data = fsg;        // claim the endpoint
      fsg->bulk_in = ep;

      ep = usb_ep_autoconfig(gadget, &fs_bulk_out_desc);
      if (!ep)
            goto autoconf_fail;
      ep->driver_data = fsg;        // claim the endpoint
      fsg->bulk_out = ep;

      if (transport_is_cbi()) {
            ep = usb_ep_autoconfig(gadget, &fs_intr_in_desc);
            if (!ep)
                  goto autoconf_fail;
            ep->driver_data = fsg;        // claim the endpoint
            fsg->intr_in = ep;
      }

      /* Fix up the descriptors */
      device_desc.bMaxPacketSize0 = fsg->ep0->maxpacket;
      device_desc.idVendor = cpu_to_le16(mod_data.vendor);
      device_desc.idProduct = cpu_to_le16(mod_data.product);
      device_desc.bcdDevice = cpu_to_le16(mod_data.release);

      i = (transport_is_cbi() ? 3 : 2);   // Number of endpoints
      intf_desc.bNumEndpoints = i;
      intf_desc.bInterfaceSubClass = mod_data.protocol_type;
      intf_desc.bInterfaceProtocol = mod_data.transport_type;
      fs_function[i + FS_FUNCTION_PRE_EP_ENTRIES] = NULL;

      if (gadget_is_dualspeed(gadget)) {
            hs_function[i + HS_FUNCTION_PRE_EP_ENTRIES] = NULL;

            /* Assume ep0 uses the same maxpacket value for both speeds */
            dev_qualifier.bMaxPacketSize0 = fsg->ep0->maxpacket;

            /* Assume endpoint addresses are the same for both speeds */
            hs_bulk_in_desc.bEndpointAddress =
                        fs_bulk_in_desc.bEndpointAddress;
            hs_bulk_out_desc.bEndpointAddress =
                        fs_bulk_out_desc.bEndpointAddress;
            hs_intr_in_desc.bEndpointAddress =
                        fs_intr_in_desc.bEndpointAddress;
      }

      if (gadget_is_otg(gadget))
            otg_desc.bmAttributes |= USB_OTG_HNP;

      rc = -ENOMEM;

      /* Allocate the request and buffer for endpoint 0 */
      fsg->ep0req = req = usb_ep_alloc_request(fsg->ep0, GFP_KERNEL);
      if (!req)
            goto out;
      req->buf = kmalloc(EP0_BUFSIZE, GFP_KERNEL);
      if (!req->buf)
            goto out;
      req->complete = ep0_complete;

      /* Allocate the data buffers */
      for (i = 0; i < NUM_BUFFERS; ++i) {
            struct fsg_buffhd *bh = &fsg->buffhds[i];

            /* Allocate for the bulk-in endpoint.  We assume that
             * the buffer will also work with the bulk-out (and
             * interrupt-in) endpoint. */
            bh->buf = kmalloc(mod_data.buflen, GFP_KERNEL);
            if (!bh->buf)
                  goto out;
            bh->next = bh + 1;
      }
      fsg->buffhds[NUM_BUFFERS - 1].next = &fsg->buffhds[0];

      /* This should reflect the actual gadget power source */
      usb_gadget_set_selfpowered(gadget);

      snprintf(manufacturer, sizeof manufacturer, "%s %s with %s",
                  init_utsname()->sysname, init_utsname()->release,
                  gadget->name);

      /* On a real device, serial[] would be loaded from permanent
       * storage.  We just encode it from the driver version string. */
      for (i = 0; i < sizeof(serial) - 2; i += 2) {
            unsigned char           c = DRIVER_VERSION[i / 2];

            if (!c)
                  break;
            sprintf(&serial[i], "%02X", c);
      }

      fsg->thread_task = kthread_create(fsg_main_thread, fsg,
                  "file-storage-gadget");
      if (IS_ERR(fsg->thread_task)) {
            rc = PTR_ERR(fsg->thread_task);
            goto out;
      }

      INFO(fsg, DRIVER_DESC ", version: " DRIVER_VERSION "\n");
      INFO(fsg, "Number of LUNs=%d\n", fsg->nluns);

      pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
      for (i = 0; i < fsg->nluns; ++i) {
            curlun = &fsg->luns[i];
            if (backing_file_is_open(curlun)) {
                  p = NULL;
                  if (pathbuf) {
                        p = d_path(&curlun->filp->f_path,
                                 pathbuf, PATH_MAX);
                        if (IS_ERR(p))
                              p = NULL;
                  }
                  LINFO(curlun, "ro=%d, file: %s\n",
                              curlun->ro, (p ? p : "(error)"));
            }
      }
      kfree(pathbuf);

      DBG(fsg, "transport=%s (x%02x)\n",
                  mod_data.transport_name, mod_data.transport_type);
      DBG(fsg, "protocol=%s (x%02x)\n",
                  mod_data.protocol_name, mod_data.protocol_type);
      DBG(fsg, "VendorID=x%04x, ProductID=x%04x, Release=x%04x\n",
                  mod_data.vendor, mod_data.product, mod_data.release);
      DBG(fsg, "removable=%d, stall=%d, cdrom=%d, buflen=%u\n",
                  mod_data.removable, mod_data.can_stall,
                  mod_data.cdrom, mod_data.buflen);
      DBG(fsg, "I/O thread pid: %d\n", task_pid_nr(fsg->thread_task));

      set_bit(REGISTERED, &fsg->atomic_bitflags);

      /* Tell the thread to start working */
      wake_up_process(fsg->thread_task);
      return 0;

autoconf_fail:
      ERROR(fsg, "unable to autoconfigure all endpoints\n");
      rc = -ENOTSUPP;

out:
      fsg->state = FSG_STATE_TERMINATED;  // The thread is dead
      fsg_unbind(gadget);
      complete(&fsg->thread_notifier);
      return rc;
}


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

static void fsg_suspend(struct usb_gadget *gadget)
{
      struct fsg_dev          *fsg = get_gadget_data(gadget);

      DBG(fsg, "suspend\n");
      set_bit(SUSPENDED, &fsg->atomic_bitflags);
}

static void fsg_resume(struct usb_gadget *gadget)
{
      struct fsg_dev          *fsg = get_gadget_data(gadget);

      DBG(fsg, "resume\n");
      clear_bit(SUSPENDED, &fsg->atomic_bitflags);
}


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

static struct usb_gadget_driver           fsg_driver = {
#ifdef CONFIG_USB_GADGET_DUALSPEED
      .speed            = USB_SPEED_HIGH,
#else
      .speed            = USB_SPEED_FULL,
#endif
      .function   = (char *) longname,
      .bind       = fsg_bind,
      .unbind           = fsg_unbind,
      .disconnect = fsg_disconnect,
      .setup            = fsg_setup,
      .suspend    = fsg_suspend,
      .resume           = fsg_resume,

      .driver           = {
            .name       = (char *) shortname,
            .owner            = THIS_MODULE,
            // .release = ...
            // .suspend = ...
            // .resume = ...
      },
};


static int __init fsg_alloc(void)
{
      struct fsg_dev          *fsg;

      fsg = kzalloc(sizeof *fsg, GFP_KERNEL);
      if (!fsg)
            return -ENOMEM;
      spin_lock_init(&fsg->lock);
      init_rwsem(&fsg->filesem);
      kref_init(&fsg->ref);
      init_completion(&fsg->thread_notifier);

      the_fsg = fsg;
      return 0;
}


static int __init fsg_init(void)
{
      int         rc;
      struct fsg_dev    *fsg;

      if ((rc = fsg_alloc()) != 0)
            return rc;
      fsg = the_fsg;
      if ((rc = usb_gadget_register_driver(&fsg_driver)) != 0)
            kref_put(&fsg->ref, fsg_release);
      return rc;
}
module_init(fsg_init);


static void __exit fsg_cleanup(void)
{
      struct fsg_dev    *fsg = the_fsg;

      /* Unregister the driver iff the thread hasn't already done so */
      if (test_and_clear_bit(REGISTERED, &fsg->atomic_bitflags))
            usb_gadget_unregister_driver(&fsg_driver);

      /* Wait for the thread to finish up */
      wait_for_completion(&fsg->thread_notifier);

      kref_put(&fsg->ref, fsg_release);
}
module_exit(fsg_cleanup);

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