[android-x86/kernel.git] / drivers / usb / gadget / f_mass_storage.c

/*
 * drivers/usb/gadget/f_mass_storage.c
 *
 * Function Driver for USB Mass Storage
 *
 * Copyright (C) 2008 Google, Inc.
 * Author: Mike Lockwood <lockwood@android.com>
 *
 * Based heavily on the file_storage gadget driver in
 * drivers/usb/gadget/file_storage.c and licensed under the same terms:
 *
 * Copyright (C) 2003-2007 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.
 */

/* #define DEBUG */
/* #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/switch.h>
#include <linux/freezer.h>
#include <linux/utsname.h>
#include <linux/wakelock.h>
#include <linux/platform_device.h>

#include <linux/usb_usual.h>
#include <linux/usb/ch9.h>
#include <linux/usb/composite.h>
#include <linux/usb/gadget.h>
#include <linux/usb/android.h>

#include "f_mass_storage.h"
#include "gadget_chips.h"


#define BULK_BUFFER_SIZE           4096

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

#define DRIVER_NAME             "usb_mass_storage"
#define MAX_LUNS                8

static const char shortname[] = DRIVER_NAME;

#ifdef DEBUG
#define LDBG(lun, fmt, args...) \
        dev_dbg(&(lun)->dev , fmt , ## args)
#define MDBG(fmt,args...) \
        printk(KERN_DEBUG DRIVER_NAME ": " fmt , ## args)
#else
#define LDBG(lun, fmt, args...) \
        do { } while (0)
#define MDBG(fmt,args...) \
        do { } while (0)
#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...) \
        printk(KERN_INFO DRIVER_NAME ": " fmt , ## args)

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


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

/* 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

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

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

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

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


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

struct 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
};

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 {
        /* This one isn't used anywhere */
        FSG_STATE_COMMAND_PHASE = -10,

        FSG_STATE_DATA_PHASE,
        FSG_STATE_STATUS_PHASE,

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

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

struct fsg_dev {
        struct usb_function function;
        struct usb_composite_dev *cdev;

        /* optional "usb_mass_storage" platform device */
        struct platform_device *pdev;

        /* lock protects: state and all the req_busy's */
        spinlock_t              lock;

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

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

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

        u8                      config, new_config;

        unsigned int            running : 1;
        unsigned int            bulk_in_enabled : 1;
        unsigned int            bulk_out_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 CLEAR_BULK_HALTS        1
#define SUSPENDED               2

        struct usb_ep           *bulk_in;
        struct usb_ep           *bulk_out;

        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;

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

        u32                             buf_size;
        const char              *vendor;
        const char              *product;
        int                             release;

        struct switch_dev sdev;

        struct wake_lock wake_lock;
};

static inline struct fsg_dev *func_to_dev(struct usb_function *f)
{
        return container_of(f, struct fsg_dev, function);
}

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 void     close_backing_file(struct fsg_dev *fsg, struct lun *curlun);
static void     close_all_backing_files(struct fsg_dev *fsg);


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

#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 */


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

/* Routines for unaligned data access */

static u16 get_be16(u8 *buf)
{
        return ((u16) buf[0] << 8) | ((u16) buf[1]);
}

static u32 get_be32(u8 *buf)
{
        return ((u32) buf[0] << 24) | ((u32) buf[1] << 16) |
                        ((u32) buf[2] << 8) | ((u32) buf[3]);
}

static void put_be16(u8 *buf, u16 val)
{
        buf[0] = val >> 8;
        buf[1] = val;
}

static void put_be32(u8 *buf, u32 val)
{
        buf[0] = val >> 24;
        buf[1] = val >> 16;
        buf[2] = val >> 8;
        buf[3] = val & 0xff;
}

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

/*
 * 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().
 */

/* 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 =   US_SC_SCSI,
        .bInterfaceProtocol =   US_PR_BULK,
};

/* 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_descriptor_header *fs_function[] = {
        (struct usb_descriptor_header *) &intf_desc,
        (struct usb_descriptor_header *) &fs_bulk_in_desc,
        (struct usb_descriptor_header *) &fs_bulk_out_desc,
        NULL,
};
#define FS_FUNCTION_PRE_EP_ENTRIES      2


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 =       __constant_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 =       __constant_cpu_to_le16(512),
        .bInterval =            1,      /* NAK every 1 uframe */
};


static struct usb_descriptor_header *hs_function[] = {
        (struct usb_descriptor_header *) &intf_desc,
        (struct usb_descriptor_header *) &hs_bulk_in_desc,
        (struct usb_descriptor_header *) &hs_bulk_out_desc,
        NULL,
};

/* 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;
}

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

/* 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;

        DBG(fsg, "raise_exception %d\n", (int)new_state);
        /* 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->state = new_state;
                if (fsg->thread_task)
                        send_sig_info(SIGUSR1, SEND_SIG_FORCED,
                                        fsg->thread_task);
        }
        spin_unlock_irqrestore(&fsg->lock, flags);
}


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

/* 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);

        /* 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);

        /* 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);
}

static int fsg_function_setup(struct usb_function *f,
                                        const struct usb_ctrlrequest *ctrl)
{
        struct fsg_dev  *fsg = func_to_dev(f);
        struct usb_composite_dev *cdev = fsg->cdev;
        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);

        DBG(fsg, "fsg_function_setup\n");
        /* Handle Bulk-only class-specific requests */
        if ((ctrl->bRequestType & USB_TYPE_MASK) == USB_TYPE_CLASS) {
        DBG(fsg, "USB_TYPE_CLASS\n");
                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 *)cdev->req->buf = fsg->nluns - 1;
                        value = 1;
                        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;
}

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

/* 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;

        DBG(fsg, "start_transfer req: %p, req->buf: %p\n", req, req->buf);
        if (ep == fsg->bulk_in)
                dump_msg(fsg, "bulk-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))
                        WARN(fsg, "error in submission: %s --> %d\n",
                                (ep == fsg->bulk_in ? "bulk-in" : "bulk-out"),
                                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 = (fsg->cmnd[1] << 16) | get_be16(&fsg->cmnd[2]);
        else {
                lba = get_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,
                                (unsigned int)fsg->buf_size);
                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 */
                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;
        }
        curlun->filp->f_flags &= ~O_SYNC;       /* Default is not to wait */

        /* Get the starting Logical Block Address and check that it's
         * not too big */
        if (fsg->cmnd[0] == SC_WRITE_6)
                lba = (fsg->cmnd[1] << 16) | get_be16(&fsg->cmnd[2]);
        else {
                lba = get_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 */
                        curlun->filp->f_flags |= O_SYNC;
        }
        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, (u32)fsg->buf_size);
                        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;
                        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.
 * The caller must own fsg->filesem.
 * This code was copied from fs/buffer.c:sys_fdatasync(). */
static int fsync_sub(struct lun *curlun)
{
        struct file     *filp = curlun->filp;
        struct inode    *inode;
        int             rc, err;

        if (curlun->ro || !filp)
                return 0;
        if (!filp->f_op->fsync)
                return -EINVAL;

        inode = filp->f_path.dentry->d_inode;
        mutex_lock(&inode->i_mutex);
        rc = filemap_fdatawrite(inode->i_mapping);
        err = filp->f_op->fsync(filp, filp->f_path.dentry, 1);
        if (!rc)
                rc = err;
        err = filemap_fdatawait(inode->i_mapping);
        if (!rc)
                rc = err;
        mutex_unlock(&inode->i_mutex);
        VLDBG(curlun, "fdatasync -> %d\n", rc);
        return rc;
}

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_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_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,
                                (unsigned int)fsg->buf_size);
                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;

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

        memset(buf, 0, 8);      /* Non-removable, direct-access device */

        buf[1] = 0x80;  /* set removable bit */
        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", fsg->vendor,
                        fsg->product, fsg->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_be32(&buf[3], sdinfo);              /* 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_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_be32(&buf[0], curlun->num_sectors - 1);     /* Max logical block */
        put_be32(&buf[4], 512);                         /* Block length */
        return 8;
}


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;
        }

        /* No block descriptors */

        /* Disabled to workaround USB reset problems with a Vista host.
         */
#if 0
        /* 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_be16(&buf[4], 0xffff);  /* Don't disable prefetch */
                                        /* Minimum prefetch = 0 */
                        put_be16(&buf[8], 0xffff);  /* Maximum prefetch */
                        /* Maximum prefetch ceiling */
                        put_be16(&buf[10], 0xffff);
                }
                buf += 12;
        }
#else
        valid_page = 1;
#endif

        /* 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_be16(buf0, len - 2);
        return len;
}

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

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

        if (loej) {
                /* eject request from the host */
                if (backing_file_is_open(curlun)) {
                        close_backing_file(fsg, curlun);
                        curlun->unit_attention_data = SS_MEDIUM_NOT_PRESENT;
                }
        }

        return 0;
}

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

        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_be32(&buf[0], curlun->num_sectors); /* Number of blocks */
        put_be32(&buf[4], 512);                         /* 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;
}


/*-------------------------------------------------------------------------*/
#if 0
static int write_zero(struct fsg_dev *fsg)
{
        struct fsg_buffhd       *bh;
        int                     rc;

        DBG(fsg, "write_zero\n");
        /* 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;
        }

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

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

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

        DBG(fsg, "throw_away_data\n");
        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) fsg->buf_size);

                        /* amount is always divisible by 512, hence by
                         * the bulk-out maxpacket size */
                        bh->outreq->length = bh->bulk_out_intended_length =
                                        amount;
                        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 */

        case DATA_DIR_UNKNOWN:
                rc = -EINVAL;
                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) {
                        start_transfer(fsg, fsg->bulk_in, bh->inreq,
                                        &bh->inreq_busy, &bh->state);
                        fsg->next_buffhd_to_fill = bh->next;
                } else {
                        start_transfer(fsg, fsg->bulk_in, bh->inreq,
                                        &bh->inreq_busy, &bh->state);
                        fsg->next_buffhd_to_fill = bh->next;
#if 0
                        /* this is unnecessary, and was causing problems with MacOS */
                        if (bh->inreq->length > 0)
                                write_zero(fsg);
#endif
                }
                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
                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;
        struct bulk_cs_wrap     *csw;

        DBG(fsg, "send_status\n");
        /* 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);
        }

        csw = bh->buf;

        /* Store and send the Bulk-only CSW */
        csw->Signature = __constant_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;
        start_transfer(fsg, fsg->bulk_in, bh->inreq,
                        &bh->inreq_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;

        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. */
                        DBG(fsg, "phase error 1\n");
                        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;
                DBG(fsg, "phase error 2\n");
                return -EINVAL;
        }

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

                /* Special case workaround: MS-Windows issues REQUEST SENSE
                 * with cbw->Length == 12 (it should be 6). */
                if (fsg->cmnd[0] == SC_REQUEST_SENSE && fsg->cmnd_size == 12)
                        cmnd_size = fsg->cmnd_size;
                else {
                        fsg->phase_error = 1;
                        return -EINVAL;
                }
        }

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

        /* 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;
                        DBG(fsg, "SS_INVALID_FIELD_IN_CDB\n");
                        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;
                DBG(fsg, "SS_MEDIUM_NOT_PRESENT\n");
                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_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_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_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_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_FORMAT_CAPACITIES:
                fsg->data_size_from_cmnd = get_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_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_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:
                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);

        VDBG(fsg, "reply: %d, fsg->data_size_from_cmnd: %d\n",
                        reply, fsg->data_size_from_cmnd);
        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? */
        if (req->status)
                return -EINVAL;

        /* Is the CBW valid? */
        if (req->actual != USB_BULK_CB_WRAP_LEN ||
                        cbw->Signature != __constant_cpu_to_le32(
                                USB_BULK_CB_SIG)) {
                DBG(fsg, "invalid CBW: len %u sig 0x%x\n",
                                req->actual,
                                le32_to_cpu(cbw->Signature));
                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);
                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;

        /* 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);
        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) {
                        usb_ep_dequeue(fsg->bulk_out, bh->outreq);
                        bh->outreq_busy = 0;
                        bh->state = BUF_STATE_EMPTY;
                        return rc;
                }
        }
        smp_rmb();
        rc = received_cbw(fsg, bh);
        bh->state = BUF_STATE_EMPTY;

        return rc;
}


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

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

        DBG(fsg, "usb_ep_enable %s\n", ep->name);
        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)
{
        struct usb_composite_dev *cdev = fsg->cdev;
        int     rc = 0;
        int     i;
        const struct usb_endpoint_descriptor    *d;

        if (fsg->running)
                DBG(fsg, "reset interface\n");
reset:
         /* Disable the endpoints */
        if (fsg->bulk_in_enabled) {
                DBG(fsg, "usb_ep_disable %s\n", fsg->bulk_in->name);
                usb_ep_disable(fsg->bulk_in);
                fsg->bulk_in_enabled = 0;
        }
        if (fsg->bulk_out_enabled) {
                DBG(fsg, "usb_ep_disable %s\n", fsg->bulk_out->name);
                usb_ep_disable(fsg->bulk_out);
                fsg->bulk_out_enabled = 0;
        }

        /* 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;
                }
        }


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

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

        /* Enable the endpoints */
        d = ep_desc(cdev->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(cdev->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);

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

                rc = alloc_request(fsg, fsg->bulk_in, &bh->inreq);
                if (rc != 0)
                        goto reset;
                rc = alloc_request(fsg, fsg->bulk_out, &bh->outreq);
                if (rc != 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;
        }

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

        return rc;
}

static void adjust_wake_lock(struct fsg_dev *fsg)
{
        int ums_active = 0;
        int i;

        spin_lock_irq(&fsg->lock);

        if (fsg->config) {
                for (i = 0; i < fsg->nluns; ++i) {
                        if (backing_file_is_open(&fsg->luns[i]))
                                ums_active = 1;
                }
        }

        if (ums_active)
                wake_lock(&fsg->wake_lock);
        else
                wake_unlock(&fsg->wake_lock);

        spin_unlock_irq(&fsg->lock);
}

/*
 * 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;

        if (new_config == fsg->config)
                return rc;

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

        /* Enable the interface */
        if (new_config != 0)
                fsg->config = new_config;

        switch_set_state(&fsg->sdev, new_config);
        adjust_wake_lock(fsg);
        return rc;
}


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

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

        DBG(fsg, "handle_exception state: %d\n", (int)fsg->state);
        /* 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);
                }
        }

        /* 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);

        /* 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];

        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:
                DBG(fsg, "FSG_STATE_ABORT_BULK_OUT\n");
                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:
                /* really not much to do here */
                break;

        case FSG_STATE_CONFIG_CHANGE:
                rc = do_set_config(fsg, new_config);
                if (new_config == 0) {
                        /* We're using the backing file */
                        down_read(&fsg->filesem);
                        fsync_all(fsg);
                        up_read(&fsg->filesem);
                }
                break;

        case FSG_STATE_EXIT:
        case FSG_STATE_TERMINATED:
                if (new_config)  {
                        fsg->new_config = 0;
                        do_set_interface(fsg, -1);
                }
                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);

        /* In case we are exiting because of a signal, unregister the
         * gadget driver and close the backing file. */
        if (test_and_clear_bit(REGISTERED, &fsg->atomic_bitflags))
                close_all_backing_files(fsg);

        /* 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 fsg_dev *fsg, 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;

        /* 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 sectors */
        if (num_sectors == 0) {
                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 size: %lld num_sectors: %lld\n",
                        filename, size, num_sectors);
        rc = 0;
        adjust_wake_lock(fsg);

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


static void close_backing_file(struct fsg_dev *fsg, struct lun *curlun)
{
        if (curlun->filp) {
                int rc;

                /*
                 * XXX: San: Ugly hack here added to ensure that
                 * our pages get synced to disk.
                 * Also drop caches here just to be extra-safe
                 */
                rc = vfs_fsync(curlun->filp, curlun->filp->f_path.dentry, 1);
                if (rc < 0)
                        printk(KERN_ERR "ums: Error syncing data (%d)\n", rc);
                /* drop_pagecache and drop_slab are no longer available */
                /* drop_pagecache(); */
                /* drop_slab(); */

                LDBG(curlun, "close backing file\n");
                fput(curlun->filp);
                curlun->filp = NULL;
                adjust_wake_lock(fsg);
        }
}

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

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

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_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;

        DBG(fsg, "store_file: \"%s\"\n", buf);
#if 0
        /* disabled because we need to allow closing the backing file if the media was removed */
        if (curlun->prevent_medium_removal && backing_file_is_open(curlun)) {
                LDBG(curlun, "eject attempt prevented\n");
                return -EBUSY;                          /* "Door is locked" */
        }
#endif

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

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

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


static DEVICE_ATTR(file, 0444, show_file, store_file);

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

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 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 ssize_t print_switch_name(struct switch_dev *sdev, char *buf)
{
        return sprintf(buf, "%s\n", DRIVER_NAME);
}

static ssize_t print_switch_state(struct switch_dev *sdev, char *buf)
{
        struct fsg_dev  *fsg = container_of(sdev, struct fsg_dev, sdev);
        return sprintf(buf, "%s\n", (fsg->config ? "online" : "offline"));
}

static void
fsg_function_unbind(struct usb_configuration *c, struct usb_function *f)
{
        struct fsg_dev  *fsg = func_to_dev(f);
        int                     i;
        struct lun              *curlun;

        DBG(fsg, "fsg_function_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_file);
                        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);
        switch_dev_unregister(&fsg->sdev);
}

static int __init
fsg_function_bind(struct usb_configuration *c, struct usb_function *f)
{
        struct usb_composite_dev *cdev = c->cdev;
        struct fsg_dev  *fsg = func_to_dev(f);
        int                     rc;
        int                     i;
        int                     id;
        struct lun              *curlun;
        struct usb_ep           *ep;
        char                    *pathbuf, *p;

        fsg->cdev = cdev;
        DBG(fsg, "fsg_function_bind\n");

        dev_attr_file.attr.mode = 0644;

        /* Find out how many LUNs there should be */
        i = fsg->nluns;
        if (i == 0)
                i = 1;
        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 = 0;
                curlun->dev.release = lun_release;
                /* use "usb_mass_storage" platform device as parent if available */
                if (fsg->pdev)
                        curlun->dev.parent = &fsg->pdev->dev;
                else
                        curlun->dev.parent = &cdev->gadget->dev;
                dev_set_drvdata(&curlun->dev, fsg);
                snprintf(curlun->dev.bus_id, BUS_ID_SIZE,
                                "lun%d", i);

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

        /* allocate interface ID(s) */
        id = usb_interface_id(c, f);
        if (id < 0)
                return id;
        intf_desc.bInterfaceNumber = id;

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

        rc = -ENOMEM;

        if (gadget_is_dualspeed(cdev->gadget)) {
                /* 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;

                f->hs_descriptors = hs_function;
        }

        /* 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(fsg->buf_size, GFP_KERNEL);
                if (!bh->buf)
                        goto out;
                bh->next = bh + 1;
        }
        fsg->buffhds[NUM_BUFFERS - 1].next = &fsg->buffhds[0];

        fsg->thread_task = kthread_create(fsg_main_thread, fsg,
                        shortname);
        if (IS_ERR(fsg->thread_task)) {
                rc = PTR_ERR(fsg->thread_task);
                ERROR(fsg, "kthread_create failed: %d\n", rc);
                goto out;
        }

        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);

        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:
        DBG(fsg, "fsg_function_bind failed: %d\n", rc);
        fsg->state = FSG_STATE_TERMINATED;      /* The thread is dead */
        fsg_function_unbind(c, f);
        close_all_backing_files(fsg);
        return rc;
}

static int fsg_function_set_alt(struct usb_function *f,
                unsigned intf, unsigned alt)
{
        struct fsg_dev  *fsg = func_to_dev(f);
        DBG(fsg, "fsg_function_set_alt intf: %d alt: %d\n", intf, alt);
        fsg->new_config = 1;
        do_set_interface(fsg, 0);
        raise_exception(fsg, FSG_STATE_CONFIG_CHANGE);
        return 0;
}

static void fsg_function_disable(struct usb_function *f)
{
        struct fsg_dev  *fsg = func_to_dev(f);
        DBG(fsg, "fsg_function_disable\n");
        if (fsg->new_config)
                do_set_interface(fsg, -1);
        fsg->new_config = 0;
        raise_exception(fsg, FSG_STATE_CONFIG_CHANGE);
}

static int __init fsg_probe(struct platform_device *pdev)
{
        struct usb_mass_storage_platform_data *pdata = pdev->dev.platform_data;
        struct fsg_dev *fsg = the_fsg;

        fsg->pdev = pdev;
        printk(KERN_INFO "fsg_probe pdata: %p\n", pdata);

        if (pdata) {
                if (pdata->vendor)
                        fsg->vendor = pdata->vendor;

                if (pdata->product)
                        fsg->product = pdata->product;

                if (pdata->release)
                        fsg->release = pdata->release;
        }

        return 0;
}

static struct platform_driver fsg_platform_driver = {
        .driver = { .name = "usb_mass_storage", },
        .probe = fsg_probe,
};

int __init mass_storage_function_add(struct usb_composite_dev *cdev,
        struct usb_configuration *c, int nluns)
{
        int             rc;
        struct fsg_dev  *fsg;

        printk(KERN_INFO "mass_storage_function_add\n");
        rc = fsg_alloc();
        if (rc)
                return rc;
        fsg = the_fsg;
        fsg->nluns = nluns;

        spin_lock_init(&fsg->lock);
        init_rwsem(&fsg->filesem);
        kref_init(&fsg->ref);
        init_completion(&fsg->thread_notifier);

        the_fsg->buf_size = BULK_BUFFER_SIZE;
        the_fsg->sdev.name = DRIVER_NAME;
        the_fsg->sdev.print_name = print_switch_name;
        the_fsg->sdev.print_state = print_switch_state;
        rc = switch_dev_register(&the_fsg->sdev);
        if (rc < 0)
                goto err_switch_dev_register;

        rc = platform_driver_register(&fsg_platform_driver);
        if (rc != 0)
                goto err_platform_driver_register;

        wake_lock_init(&the_fsg->wake_lock, WAKE_LOCK_SUSPEND,
                       "usb_mass_storage");

        fsg->cdev = cdev;
        fsg->function.name = shortname;
        fsg->function.descriptors = fs_function;
        fsg->function.bind = fsg_function_bind;
        fsg->function.unbind = fsg_function_unbind;
        fsg->function.setup = fsg_function_setup;
        fsg->function.set_alt = fsg_function_set_alt;
        fsg->function.disable = fsg_function_disable;

        rc = usb_add_function(c, &fsg->function);
        if (rc != 0)
                goto err_usb_add_function;


        return 0;

err_usb_add_function:
        platform_driver_unregister(&fsg_platform_driver);
err_platform_driver_register:
        switch_dev_unregister(&the_fsg->sdev);
err_switch_dev_register:
        kref_put(&the_fsg->ref, fsg_release);

        return rc;
}