xref: /kernel/linux/linux-6.6/drivers/usb/gadget/function/f_generic.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * f_fs.c -- user mode file system API for USB composite function controllers
 *
 * Copyright (C) 2010 Samsung Electronics
 * Author: Michal Nazarewicz <mina86@mina86.com>
 *
 * Based on inode.c (GadgetFS) which was:
 * Copyright (C) 2003-2004 David Brownell
 * Copyright (C) 2003 Agilent Technologies
 */

/* #define DEBUG */
/* #define VERBOSE_DEBUG */

#include <linux/export.h>
#include <linux/hid.h>
#include <linux/miscdevice.h>
#include <linux/usb/functionfs.h>
#include <linux/kfifo.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/eventfd.h>
#include <linux/dma-mapping.h>
#include <linux/usb/cdc.h>
#include <linux/interrupt.h>
#include "u_generic.h"
#include "u_f.h"
#include "u_os_desc.h"
#include "configfs.h"

#define FUNCTIONFS_MAGIC    0xa647361 /* Chosen by a honest dice roll ;) */

/* Reference counter handling */
static void ffs_data_get(struct ffs_data *ffs);
static void ffs_data_put(struct ffs_data *ffs);
/* Creates new ffs_data object. */
static struct ffs_data *__must_check ffs_data_new(const char *dev_name)
    __attribute__((malloc));

/* Called with ffs->mutex held; take over ownership of data. */
static int __must_check
__ffs_data_got_descs(struct ffs_data *ffs, char *data, size_t len);
static int __must_check
__ffs_data_got_strings(struct ffs_data *ffs, char *data, size_t len);

/* The function structure ***************************************************/

struct ffs_ep;

struct ffs_function {
    struct usb_configuration    *conf;
    struct usb_gadget        *gadget;
    struct ffs_data            *ffs;

    struct ffs_ep            *eps;
    u8                eps_revmap[16];
    short                *interfaces_nums;

    struct usb_function        function;
};
static struct ffs_function *ffs_func_from_usb(struct usb_function *f)
{
    return container_of(f, struct ffs_function, function);
}
static inline enum ffs_setup_state ffs_setup_state_clear_cancelled(struct ffs_data *ffs)
{
    return (enum ffs_setup_state)
        cmpxchg(&ffs->setup_state, FFS_SETUP_CANCELLED, FFS_NO_SETUP);
}
static void ffs_func_eps_disable(struct ffs_function *func);
static int __must_check ffs_func_eps_enable(struct ffs_function *func);

static int ffs_func_bind(struct usb_configuration *,
             struct usb_function *);
static int ffs_func_set_alt(struct usb_function *, unsigned, unsigned);
static void ffs_func_disable(struct usb_function *);
static int ffs_func_setup(struct usb_function *,
              const struct usb_ctrlrequest *);
static bool ffs_func_req_match(struct usb_function *,
                   const struct usb_ctrlrequest *,
                   bool config0);
static void ffs_func_suspend(struct usb_function *);
static void ffs_func_resume(struct usb_function *);

static int ffs_func_revmap_ep(struct ffs_function *func, u8 num);
static int ffs_func_revmap_intf(struct ffs_function *func, u8 intf);

/* The endpoints structures *************************************************/
struct ffs_ep {
    struct usb_ep            *ep;    /* P: ffs->eps_lock */
    struct usb_request        *req;    /* P: epfile->mutex */

    /* [0]: full speed, [1]: high speed, [2]: super speed */
    struct usb_endpoint_descriptor    *descs[3];

    u8                num;

    int                status;    /* P: epfile->mutex */
};

struct ffs_epfile {
    /* Protects ep->ep and ep->req. */
    struct mutex            mutex;
    struct list_head         memory_list;
    struct ffs_data            *ffs;
    struct ffs_ep            *ep;    /* P: ffs->eps_lock */
    /*
     * Buffer for holding data from partial reads which may happen since
     * we’re rounding user read requests to a multiple of a max packet size.
     *
     * The pointer is initialised with NULL value and may be set by
     * __ffs_epfile_read_data function to point to a temporary buffer.
     *
     * In normal operation, calls to __ffs_epfile_read_buffered will consume
     * data from said buffer and eventually free it.  Importantly, while the
     * function is using the buffer, it sets the pointer to NULL.  This is
     * all right since __ffs_epfile_read_data and __ffs_epfile_read_buffered
     * can never run concurrently (they are synchronised by epfile->mutex)
     * so the latter will not assign a new value to the pointer.
     *
     * Meanwhile ffs_func_eps_disable frees the buffer (if the pointer is
     * valid) and sets the pointer to READ_BUFFER_DROP value.  This special
     * value is crux of the synchronisation between ffs_func_eps_disable and
     * __ffs_epfile_read_data.
     *
     * Once __ffs_epfile_read_data is about to finish it will try to set the
     * pointer back to its old value (as described above), but seeing as the
     * pointer is not-NULL (namely READ_BUFFER_DROP) it will instead free
     * the buffer.
     *
     * == State transitions ==
     *
     * • ptr == NULL:  (initial state)
     *   ◦ __ffs_epfile_read_buffer_free: go to ptr == DROP
     *   ◦ __ffs_epfile_read_buffered:    nop
     *   ◦ __ffs_epfile_read_data allocates temp buffer: go to ptr == buf
     *   ◦ reading finishes:              n/a, not in ‘and reading’ state
     * • ptr == DROP:
     *   ◦ __ffs_epfile_read_buffer_free: nop
     *   ◦ __ffs_epfile_read_buffered:    go to ptr == NULL
     *   ◦ __ffs_epfile_read_data allocates temp buffer: free buf, nop
     *   ◦ reading finishes:              n/a, not in ‘and reading’ state
     * • ptr == buf:
     *   ◦ __ffs_epfile_read_buffer_free: free buf, go to ptr == DROP
     *   ◦ __ffs_epfile_read_buffered:    go to ptr == NULL and reading
     *   ◦ __ffs_epfile_read_data:        n/a, __ffs_epfile_read_buffered
     *                                    is always called first
     *   ◦ reading finishes:              n/a, not in ‘and reading’ state
     * • ptr == NULL and reading:
     *   ◦ __ffs_epfile_read_buffer_free: go to ptr == DROP and reading
     *   ◦ __ffs_epfile_read_buffered:    n/a, mutex is held
     *   ◦ __ffs_epfile_read_data:        n/a, mutex is held
     *   ◦ reading finishes and …
     *     … all data read:               free buf, go to ptr == NULL
     *     … otherwise:                   go to ptr == buf and reading
     * • ptr == DROP and reading:
     *   ◦ __ffs_epfile_read_buffer_free: nop
     *   ◦ __ffs_epfile_read_buffered:    n/a, mutex is held
     *   ◦ __ffs_epfile_read_data:        n/a, mutex is held
     *   ◦ reading finishes:              free buf, go to ptr == DROP
     */
    struct ffs_buffer        *read_buffer;
#define READ_BUFFER_DROP ((struct ffs_buffer *)ERR_PTR(-ESHUTDOWN))

    char                name[MAX_NAMELEN];
    dev_t                devno;
    struct cdev         cdev;
    struct device         *device;

    unsigned char            in;    /* P: ffs->eps_lock */
    unsigned char            isoc;    /* P: ffs->eps_lock */

    struct kfifo        reqEventFifo;
    wait_queue_head_t   wait_que;

    unsigned char            _pad;
};

struct ffs_buffer {
    size_t length;
    char *data;
    char storage[];
};

/*  ffs_io_data structure ***************************************************/

struct ffs_io_data {
    uint32_t aio;
    uint32_t read;
    uint32_t len;
    uint32_t timeout;
    uint64_t buf;
    uint32_t actual;
    int      status;
    struct tasklet_struct task;
    struct usb_ep *ep;
    struct usb_request *req;
    struct ffs_epfile *epfile;
    struct ffs_data *ffs;
};

struct ffs_desc_helper {
    struct ffs_data *ffs;
    unsigned interfaces_count;
    unsigned eps_count;
};

static int  __must_check ffs_epfiles_create(struct ffs_data *ffs);
static void ffs_epfiles_destroy(struct ffs_epfile *epfiles, unsigned count);

/* Devices management *******************************************************/

DEFINE_MUTEX(ffs_lock_adapter);
EXPORT_SYMBOL_GPL(ffs_lock_adapter);

static struct ffs_dev *_ffs_find_dev(const char *name);
static struct ffs_dev *_ffs_alloc_dev(void);
static void _ffs_free_dev(struct ffs_dev *dev);
static void *ffs_acquire_dev(const char *dev_name);
static void ffs_release_dev(struct ffs_data *ffs_data);
static int ffs_ready(struct ffs_data *ffs);
static void ffs_closed(struct ffs_data *ffs);

/* Misc helper functions ****************************************************/

static int ffs_mutex_lock(struct mutex *mutex, unsigned nonblock)
    __attribute__((warn_unused_result, nonnull));
static char *ffs_prepare_buffer(const char __user *buf, size_t len)
    __attribute__((warn_unused_result, nonnull));

struct class *ffs_class;

static char *ffs_devnode(const struct device *dev, umode_t *mode)
{
    if (mode)
        *mode = 0666;
    return kasprintf(GFP_KERNEL, "functionfs/%s", dev_name(dev));
}

/* Control file aka ep0 *****************************************************/
static struct ffs_memory *generic_find_ep0_memory_area(struct ffs_data *ffs, uint64_t buf, uint32_t len)
{
    struct ffs_memory *ffsm = NULL;
    struct ffs_memory *iter = NULL;
    uint64_t buf_start = buf;
    unsigned long flags;

    spin_lock_irqsave(&ffs->mem_lock, flags);
    list_for_each_entry(iter, &ffs->memory_list, memlist) {
        if (buf_start >= iter->vm_start &&
            buf_start < iter->vm_start + iter->size) {
            if (len <= iter->vm_start + iter->size - buf_start) {
                ffsm = iter;
                break;
            }
        }
    }
    spin_unlock_irqrestore(&ffs->mem_lock, flags);
    return ffsm;
}

static void ffs_ep0_complete(struct usb_ep *ep, struct usb_request *req)
{
    struct ffs_data *ffs = req->context;

    complete(&ffs->ep0req_completion);

    ffs->setup_state = FFS_NO_SETUP;
}

static void ffs_ep0_async_io_complete(struct usb_ep *_ep, struct usb_request *req)
{
    struct ffs_io_data *io_data = req->context;
    struct ffs_data *ffs = io_data->ffs;
    ENTER();

    io_data->status = io_data->req->status;
    io_data->actual = io_data->req->actual;
    kfifo_in(&ffs->reqEventFifo, &io_data->buf, sizeof(struct UsbFnReqEvent));
    wake_up_all(&ffs->wait_que);

    list_del(&req->list);
    usb_ep_free_request(io_data->ep, io_data->req);
    kfree(io_data);

}

static int __ffs_ep0_queue_wait(struct ffs_data *ffs, char *data, size_t len)
    __releases(&ffs->ev.waitq.lock)
{
    struct usb_request *req = ffs->ep0req;
    int ret;

    req->zero     = len < le16_to_cpu(ffs->ev.setup.wLength);

    spin_unlock_irq(&ffs->ev.waitq.lock);

    req->buf      = data;
    req->length   = len;

    /*
     * UDC layer requires to provide a buffer even for ZLP, but should
     * not use it at all. Let's provide some poisoned pointer to catch
     * possible bug in the driver.
     */
    if (req->buf == NULL)
        req->buf = (void *)0xDEADBABE;

    reinit_completion(&ffs->ep0req_completion);

    ret = usb_ep_queue(ffs->gadget->ep0, req, GFP_ATOMIC);
    if (unlikely(ret < 0))
        return ret;

    ret = wait_for_completion_interruptible(&ffs->ep0req_completion);
    if (unlikely(ret)) {
        usb_ep_dequeue(ffs->gadget->ep0, req);
        return -EINTR;
    }

    ffs->setup_state = FFS_NO_SETUP;
    return req->status ? req->status : req->actual;
}

static int __ffs_ep0_stall(struct ffs_data *ffs)
{
    if (ffs->ev.can_stall) {
        pr_vdebug("ep0 stall\n");
        usb_ep_set_halt(ffs->gadget->ep0);
        ffs->setup_state = FFS_NO_SETUP;
        return -EL2HLT;
    } else {
        pr_debug("bogus ep0 stall!\n");
        return -ESRCH;
    }
}

static ssize_t ffs_ep0_write(struct file *file, const char __user *buf, size_t len, loff_t *ptr)
{
    struct ffs_data *ffs = file->private_data;
    ssize_t ret;
    char *data = NULL;

    ENTER();

    /* Fast check if setup was canceled */
    if (ffs_setup_state_clear_cancelled(ffs) == FFS_SETUP_CANCELLED)
        return -EIDRM;

    /* Acquire mutex */
    ret = ffs_mutex_lock(&ffs->mutex, file->f_flags & O_NONBLOCK);
    if (unlikely(ret < 0))
        return ret;

    /* Check state */
    switch (ffs->state) {
    case FFS_READ_DESCRIPTORS:
    case FFS_READ_STRINGS:
        /* Copy data */
        if (unlikely(len < 16)) {
            ret = -EINVAL;
            break;
        }

        data = ffs_prepare_buffer(buf, len);
        if (IS_ERR(data)) {
            ret = PTR_ERR(data);
            break;
        }

        /* Handle data */
        if (ffs->state == FFS_READ_DESCRIPTORS) {
            pr_info("read descriptors\n");
            ret = __ffs_data_got_descs(ffs, data, len);
            if (unlikely(ret < 0))
                break;

            ffs->state = FFS_READ_STRINGS;
            ret = len;
        } else {
            pr_info("read strings\n");
            ret = __ffs_data_got_strings(ffs, data, len);
            if (unlikely(ret < 0))
                break;

            ret = ffs_epfiles_create(ffs);
            if (unlikely(ret)) {
                ffs->state = FFS_CLOSING;
                break;
            }

            ffs->state = FFS_ACTIVE;
            mutex_unlock(&ffs->mutex);

            ret = ffs_ready(ffs);
            if (unlikely(ret < 0)) {
                ffs->state = FFS_CLOSING;
                return ret;
            }

            return len;
        }
        break;

    case FFS_ACTIVE:
        data = NULL;
        /*
         * We're called from user space, we can use _irq
         * rather then _irqsave
         */
        spin_lock_irq(&ffs->ev.waitq.lock);
        switch (ffs_setup_state_clear_cancelled(ffs)) {
        case FFS_SETUP_CANCELLED:
            ret = -EIDRM;
            goto done_spin;

        case FFS_NO_SETUP:
            ret = -ESRCH;
            goto done_spin;

        case FFS_SETUP_PENDING:
            break;
        }

        /* FFS_SETUP_PENDING */
        if (!(ffs->ev.setup.bRequestType & USB_DIR_IN)) {
            spin_unlock_irq(&ffs->ev.waitq.lock);
            ret = __ffs_ep0_stall(ffs);
            break;
        }

        /* FFS_SETUP_PENDING and not stall */
        len = min(len, (size_t)le16_to_cpu(ffs->ev.setup.wLength));

        spin_unlock_irq(&ffs->ev.waitq.lock);

        data = ffs_prepare_buffer(buf, len);
        if (IS_ERR(data)) {
            ret = PTR_ERR(data);
            break;
        }

        spin_lock_irq(&ffs->ev.waitq.lock);

        /*
         * We are guaranteed to be still in FFS_ACTIVE state
         * but the state of setup could have changed from
         * FFS_SETUP_PENDING to FFS_SETUP_CANCELLED so we need
         * to check for that.  If that happened we copied data
         * from user space in vain but it's unlikely.
         *
         * For sure we are not in FFS_NO_SETUP since this is
         * the only place FFS_SETUP_PENDING -> FFS_NO_SETUP
         * transition can be performed and it's protected by
         * mutex.
         */
        if (ffs_setup_state_clear_cancelled(ffs) ==
                FFS_SETUP_CANCELLED) {
                ret = -EIDRM;
done_spin:
            spin_unlock_irq(&ffs->ev.waitq.lock);
        } else {
            /* unlocks spinlock */
            ret = __ffs_ep0_queue_wait(ffs, data, len);
        }
        kfree(data);
        break;

    default:
        ret = -EBADFD;
        break;
    }

    mutex_unlock(&ffs->mutex);
    return ret;
}

/* Called with ffs->ev.waitq.lock and ffs->mutex held, both released on exit. */
static ssize_t __ffs_ep0_read_events(struct ffs_data *ffs, char __user *buf, size_t n)
    __releases(&ffs->ev.waitq.lock)
{
    /*
     * n cannot be bigger than ffs->ev.count, which cannot be bigger than
     * size of ffs->ev.types array (which is four) so that's how much space
     * we reserve.
     */
    struct usb_functionfs_event events[ARRAY_SIZE(ffs->ev.types)];
    const size_t size = n * sizeof *events;
    unsigned i = 0;

    memset(events, 0, size);

    do {
        events[i].type = ffs->ev.types[i];
        if (events[i].type == FUNCTIONFS_SETUP) {
            events[i].u.setup = ffs->ev.setup;
            ffs->setup_state = FFS_SETUP_PENDING;
        }
    } while (++i < n);

    ffs->ev.count -= n;
    if (ffs->ev.count)
        memmove(ffs->ev.types, ffs->ev.types + n, ffs->ev.count * sizeof *ffs->ev.types);

    spin_unlock_irq(&ffs->ev.waitq.lock);
    mutex_unlock(&ffs->mutex);

    return unlikely(copy_to_user(buf, events, size)) ? -EFAULT : size;
}

static ssize_t ffs_ep0_read(struct file *file, char __user *buf, size_t len, loff_t *ptr)
{
    struct ffs_data *ffs = file->private_data;
    char *data = NULL;
    size_t n;
    int ret;

    ENTER();

    /* Fast check if setup was canceled */
    if (ffs_setup_state_clear_cancelled(ffs) == FFS_SETUP_CANCELLED)
        return -EIDRM;

    /* Acquire mutex */
    ret = ffs_mutex_lock(&ffs->mutex, file->f_flags & O_NONBLOCK);
    if (unlikely(ret < 0))
        return ret;

    /* Check state */
    if (ffs->state != FFS_ACTIVE) {
        ret = -EBADFD;
        goto done_mutex;
    }

    /*
     * We're called from user space, we can use _irq rather then
     * _irqsave
     */
    spin_lock_irq(&ffs->ev.waitq.lock);

    switch (ffs_setup_state_clear_cancelled(ffs)) {
    case FFS_SETUP_CANCELLED:
        ret = -EIDRM;
        break;

    case FFS_NO_SETUP:
        n = len / sizeof(struct usb_functionfs_event);
        if (unlikely(!n)) {
            ret = -EINVAL;
            break;
        }

        if ((file->f_flags & O_NONBLOCK) && !ffs->ev.count) {
            ret = -EAGAIN;
            break;
        }

        if (wait_event_interruptible_exclusive_locked_irq(ffs->ev.waitq,
                            ffs->ev.count)) {
            ret = -EINTR;
            break;
        }

        /* unlocks spinlock */
        return __ffs_ep0_read_events(ffs, buf,
                         min(n, (size_t)ffs->ev.count));

    case FFS_SETUP_PENDING:
        if (ffs->ev.setup.bRequestType & USB_DIR_IN) {
            spin_unlock_irq(&ffs->ev.waitq.lock);
            ret = __ffs_ep0_stall(ffs);
            goto done_mutex;
        }

        len = min(len, (size_t)le16_to_cpu(ffs->ev.setup.wLength));

        spin_unlock_irq(&ffs->ev.waitq.lock);

        if (likely(len)) {
            data = kmalloc(len, GFP_KERNEL);
            if (unlikely(!data)) {
                ret = -ENOMEM;
                goto done_mutex;
            }
        }

        spin_lock_irq(&ffs->ev.waitq.lock);

        /* See ffs_ep0_write() */
        if (ffs_setup_state_clear_cancelled(ffs) ==
            FFS_SETUP_CANCELLED) {
            ret = -EIDRM;
            break;
        }

        /* unlocks spinlock */
        ret = __ffs_ep0_queue_wait(ffs, data, len);
        if (likely(ret > 0) && unlikely(copy_to_user(buf, data, len)))
            ret = -EFAULT;
        goto done_mutex;

    default:
        ret = -EBADFD;
        break;
    }

    spin_unlock_irq(&ffs->ev.waitq.lock);
done_mutex:
    mutex_unlock(&ffs->mutex);
    kfree(data);
    return ret;
}

static int ffs_ep0_open(struct inode *inode, struct file *file)
{
    struct ffs_data *ffs  = container_of(inode->i_cdev, struct ffs_data, cdev);
    ENTER();

    if (unlikely(ffs->state == FFS_CLOSING))
        return -EBUSY;

    file->private_data = ffs;
    return 0;
}

static int ffs_ep0_release(struct inode *inode, struct file *file)
{
    ENTER();
    return 0;
}

static ssize_t ffs_ep0_iorw(struct file *file, struct ffs_io_data *io_data)
{
    struct ffs_data *ffs = file->private_data;
    struct usb_request *req = NULL;
    ssize_t ret, data_len = io_data->len;
    bool interrupted = false;
    struct ffs_memory *ffsm = NULL;

    /* Are we still active? */
    if (WARN_ON(ffs->state != FFS_ACTIVE))
        return -ENODEV;
    ffsm = generic_find_ep0_memory_area(ffs, io_data->buf, data_len);
    if (ffsm == NULL)
    {
        return -ENODEV;
    }
    if (!io_data->aio) {
        reinit_completion(&ffs->ep0req_completion);

        req = ffs->ep0req;
        req->buf      = (void *)(ffsm->mem + io_data->buf - ffsm->vm_start);
        req->length   = data_len;
        req->complete = ffs_ep0_complete;

        ret = usb_ep_queue(ffs->gadget->ep0, req, GFP_ATOMIC);
        if (unlikely(ret < 0))
            goto error;

        if (io_data->timeout > 0) {
            ret = wait_for_completion_interruptible_timeout(&ffs->ep0req_completion, io_data->timeout);
            if (ret < 0) {
                /*
                 * To avoid race condition with ffs_epfile_io_complete,
                 * dequeue the request first then check
                 * status. usb_ep_dequeue API should guarantee no race
                 * condition with req->complete callback.
                 */
                usb_ep_dequeue(ffs->gadget->ep0, req);
                wait_for_completion(&ffs->ep0req_completion);
                interrupted = req->status < 0;
            } else if (ret == 0) {
                ret = -EBUSY;
                usb_ep_dequeue(ffs->gadget->ep0, req);
                wait_for_completion(&ffs->ep0req_completion);
                goto error;
            }
        } else {
            ret = wait_for_completion_interruptible(&ffs->ep0req_completion);
            if (ret < 0) {
                usb_ep_dequeue(ffs->gadget->ep0, req);
                wait_for_completion(&ffs->ep0req_completion);
                interrupted = req->status < 0;
            }
        }

        if (interrupted) {
            ret = -EINTR;
        } else {
            ret = req->actual;
        }
        goto error;
    }
    else if (!(req = usb_ep_alloc_request(ffs->gadget->ep0, GFP_ATOMIC))) {
        ret = -ENOMEM;
    }
    else {
        req->buf     = (void *)(ffsm->mem + io_data->buf - ffsm->vm_start);
        req->length   = data_len;

        io_data->ep = ffs->gadget->ep0;
        io_data->req = req;
        io_data->ffs = ffs;

        req->context  = io_data;
        req->complete = ffs_ep0_async_io_complete;
        list_add(&req->list, &ffs->ep0req->list);
        ret = usb_ep_queue(ffs->gadget->ep0, req, GFP_ATOMIC);
        if (unlikely(ret)) {
            usb_ep_free_request(ffs->gadget->ep0, req);
            goto error;
        }

        ret = -EIOCBQUEUED;
    }

error:
    return ret;
}

static long ffs_ep0_ioctl(struct file *file, unsigned code, unsigned long value)
{
    struct ffs_data *ffs = file->private_data;
    long ret = 0;
    unsigned int copied = 0;
    struct ffs_memory *ffsm = NULL;
    struct generic_memory mem;

    ENTER();

    switch (code) {
    case FUNCTIONFS_ENDPOINT_QUEUE_INIT:
        ret = kfifo_alloc(&ffs->reqEventFifo, MAX_REQUEST * sizeof(struct UsbFnReqEvent), GFP_KERNEL);
        break;
    case FUNCTIONFS_ENDPOINT_QUEUE_DEL:
        kfifo_free(&ffs->reqEventFifo);
        break;
    case FUNCTIONFS_ENDPOINT_RELEASE_BUF:
        if (copy_from_user(&mem, (void __user *)value, sizeof(mem)))
        {
            pr_info("copy from user failed\n");
            return -EFAULT;
        }
        ffsm = generic_find_ep0_memory_area(ffs, mem.buf, mem.size);
        if (ffsm == NULL)
        {
            return -EFAULT;
        }
        list_del(&ffsm->memlist);
        kfree((void *)ffsm->mem);
        kfree(ffsm);
        break;
    case FUNCTIONFS_ENDPOINT_READ:
    case FUNCTIONFS_ENDPOINT_WRITE:
    {
        struct IoData myIoData;
        struct ffs_io_data io_data, *p = &io_data;
        ret = copy_from_user(&myIoData, (void __user *)value, sizeof(struct IoData));
        if (unlikely(ret)) {
            return -EFAULT;
        }
        if (myIoData.aio) {
            p = kmalloc(sizeof(io_data), GFP_KERNEL);
            if (unlikely(!p))
                return -ENOMEM;
        } else {
            memset(p, 0, sizeof(*p));
        }
        memcpy(p, &myIoData, sizeof(struct IoData));

        ret = ffs_ep0_iorw(file, p);
        if (ret == -EIOCBQUEUED) {
            return 0;
        }
        if (p->aio)
            kfree(p);
        return ret;
    }
    case FUNCTIONFS_ENDPOINT_RW_CANCEL:
    {
        struct usb_request *req;
        struct IoData myIoData;
        ret = copy_from_user(&myIoData, (void __user *)value, sizeof(struct IoData));
        if (unlikely(ret)) {
            return -EFAULT;
        }
        ffsm = generic_find_ep0_memory_area(ffs, myIoData.buf, myIoData.len);
        if (ffsm == NULL)
        {
            return -EFAULT;
        }
        list_for_each_entry(req, &ffs->ep0req->list, list) {
            if (req->buf == (void *)(ffsm->mem + myIoData.buf - ffsm->vm_start)) {
                usb_ep_dequeue(ffs->gadget->ep0, req);
                return 0;
            }
        }
        return -EFAULT;
    }
    case FUNCTIONFS_ENDPOINT_GET_REQ_STATUS:
    {
        struct usb_request *req;
        struct IoData myIoData;
        ret = copy_from_user(&myIoData, (void __user *)value, sizeof(struct IoData));
        if (unlikely(ret)) {
            return -EFAULT;
        }
        ffsm = generic_find_ep0_memory_area(ffs, myIoData.buf, myIoData.len);
        if (ffsm == NULL)
        {
            return -EFAULT;
        }
        list_for_each_entry(req, &ffs->ep0req->list, list) {
            if (req->buf == (void *)(ffsm->mem + myIoData.buf - ffsm->vm_start)) {
                return req->status;
            }
        }
        return -EFAULT;
    }
    case FUNCTIONFS_ENDPOINT_GET_EP0_EVENT:
        if (!kfifo_is_empty(&ffs->reqEventFifo)) {
            ret = kfifo_to_user(&ffs->reqEventFifo, (void __user *)value,
            sizeof(struct UsbFnReqEvent), &copied) == 0 ? copied : -1;
            if (ret > 0) {
                ffs->setup_state = FFS_NO_SETUP;
                return ret;
            }
        }

        return -EFAULT;
    }

    return ret;
}

#ifdef CONFIG_COMPAT
static long ffs_ep0_compat_ioctl(struct file *file, unsigned code,
        unsigned long value)
{
    return ffs_ep0_ioctl(file, code, value);
}
#endif

static __poll_t ffs_ep0_poll(struct file *file, poll_table *wait)
{
    struct ffs_data *ffs = file->private_data;
    __poll_t mask = EPOLLWRNORM;
    int ret;

    ret = ffs_mutex_lock(&ffs->mutex, file->f_flags & O_NONBLOCK);
    if (unlikely(ret < 0))
        return mask;

    switch (ffs->state) {
    case FFS_READ_DESCRIPTORS:
    case FFS_READ_STRINGS:
        mask |= EPOLLOUT;
        break;

    case FFS_ACTIVE:
        switch (ffs->setup_state) {
        case FFS_NO_SETUP:
            poll_wait(file, &ffs->ev.waitq, wait);
            if (ffs->ev.count)
                mask |= EPOLLIN;
            break;

        case FFS_SETUP_PENDING:
        case FFS_SETUP_CANCELLED:
            poll_wait(file, &ffs->wait_que, wait);
            if (!kfifo_is_empty(&ffs->reqEventFifo))
            {
                mask |= EPOLLOUT;
            }
            break;
        }
    case FFS_CLOSING:
        break;
    case FFS_DEACTIVATED:
        break;
    }

    mutex_unlock(&ffs->mutex);

    return mask;
}

static int ffs_ep0_mmap(struct file *file, struct vm_area_struct *vma)
{
    struct ffs_data *ffs = file->private_data;
    size_t size = vma->vm_end - vma->vm_start;
    unsigned long flags;
    struct ffs_memory *ffsm = NULL;
    void *virt_mem = NULL;

    if (ffs == NULL) {
        pr_info("Invalid private parameter!\n");
        return -EINVAL;
    }
    virt_mem = kmalloc(size, GFP_KERNEL);
    if (virt_mem == NULL)
    {
        pr_info("%s alloc memory failed!\n", __FUNCTION__);
        return -ENOMEM;
    }
    ffsm = kmalloc(sizeof(struct ffs_memory), GFP_KERNEL);
    if (ffsm == NULL)
    {
        pr_info("%s alloc memory failed!\n", __FUNCTION__);
        goto error_free_mem;
    }
    if (remap_pfn_range(vma, vma->vm_start, virt_to_phys(virt_mem)>>PAGE_SHIFT,
        vma->vm_end - vma->vm_start, vma->vm_page_prot)) {
        goto error_free_ffsm;
    }
    ffsm->mem      = (uint64_t)virt_mem;
    ffsm->size     = size;
    ffsm->vm_start = vma->vm_start;
    INIT_LIST_HEAD(&ffsm->memlist);
    spin_lock_irqsave(&ffs->mem_lock, flags);
    list_add_tail(&ffsm->memlist, &ffs->memory_list);
    spin_unlock_irqrestore(&ffs->mem_lock, flags);
    return 0;
error_free_ffsm:
    kfree(ffsm);
error_free_mem:
    kfree(virt_mem);
    return -1;
}

static const struct file_operations ffs_ep0_operations = {
    .owner   = THIS_MODULE,
    .llseek =    no_llseek,
    .open =        ffs_ep0_open,
    .write =    ffs_ep0_write,
    .read =        ffs_ep0_read,
    .release =    ffs_ep0_release,
    .unlocked_ioctl =    ffs_ep0_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl = ffs_ep0_compat_ioctl,
#endif
    .poll =        ffs_ep0_poll,
    .mmap =     ffs_ep0_mmap,
};

/* "Normal" endpoints operations ********************************************/
static struct ffs_memory *generic_find_memory_area(struct ffs_epfile *epfile, uint64_t buf, uint32_t len)
{
    struct ffs_memory *ffsm = NULL, *iter = NULL;
    uint64_t buf_start = buf;

    list_for_each_entry(iter, &epfile->memory_list, memlist) {
        if (buf_start >= iter->vm_start &&
            buf_start < iter->vm_start + iter->size) {
            if (len <= iter->vm_start + iter->size - buf_start) {
                ffsm = iter;
                break;
            }
        }
    }
    return ffsm;
}

static void ffs_epfile_io_complete(struct usb_ep *_ep, struct usb_request *req)
{
    ENTER();
    if (likely(req->context)) {
        struct ffs_ep *ep = _ep->driver_data;
        ep->status = req->status ? req->status : req->actual;
        complete(req->context);
    }
}

static void epfile_task_proc(unsigned long context)
{
    struct ffs_io_data *io_data = (struct ffs_io_data *)context;
    struct ffs_epfile *epfile = io_data->epfile;
    unsigned long flags;

    spin_lock_irqsave(&epfile->ffs->eps_lock, flags);
    io_data->status = io_data->req->status;
    io_data->actual = io_data->req->actual;
    kfifo_in(&epfile->reqEventFifo, &io_data->buf, sizeof(struct UsbFnReqEvent));
    list_del(&io_data->req->list);
    usb_ep_free_request(io_data->ep, io_data->req);
    kfree(io_data);
    spin_unlock_irqrestore(&epfile->ffs->eps_lock, flags);
    wake_up_all(&epfile->wait_que);
}

static void ffs_epfile_async_io_complete(struct usb_ep *_ep, struct usb_request *req)
{
    struct ffs_io_data *io_data = req->context;

    tasklet_init(&io_data->task, epfile_task_proc, (uintptr_t)io_data);
    tasklet_schedule(&io_data->task);

}

static int ffs_epfile_open(struct inode *inode, struct file *file)
{
    struct ffs_epfile *epfile  = container_of(inode->i_cdev, struct ffs_epfile, cdev);
    ENTER();
    if (WARN_ON(epfile->ffs->state != FFS_ACTIVE))
        return -ENODEV;

    file->private_data = epfile;
    return 0;
}

static int ffs_epfile_release(struct inode *inode, struct file *file)
{
    ENTER();
    return 0;
}

static int ffs_epfile_mmap(struct file *file, struct vm_area_struct *vma)
{
    struct ffs_epfile *epfile = file->private_data;
    size_t size = vma->vm_end - vma->vm_start;
    struct ffs_memory *ffsm = NULL;
    unsigned long flags;
    void *virt_mem = NULL;

    if (epfile == NULL)
    {
        pr_info("Invalid private parameter!\n");
        return -EINVAL;
    }
    virt_mem = kmalloc(size, GFP_KERNEL);
    if (virt_mem == NULL)
    {
        pr_info("%s alloc memory failed!\n", __FUNCTION__);
        return -ENOMEM;
    }
    ffsm = kmalloc(sizeof(struct ffs_memory), GFP_KERNEL);
    if (ffsm == NULL)
    {
        pr_info("%s alloc memory failed!\n", __FUNCTION__);
        goto error_free_mem;
    }
    if (remap_pfn_range(vma, vma->vm_start, virt_to_phys(virt_mem)>>PAGE_SHIFT,
                vma->vm_end - vma->vm_start, vma->vm_page_prot))
    {
        goto error_free_ffsm;
    }
    ffsm->mem = (uint64_t)virt_mem;
    ffsm->size = size;
    ffsm->vm_start = vma->vm_start;
    INIT_LIST_HEAD(&ffsm->memlist);
    spin_lock_irqsave(&epfile->ffs->eps_lock, flags);
    list_add_tail(&ffsm->memlist, &epfile->memory_list);
    spin_unlock_irqrestore(&epfile->ffs->eps_lock, flags);

    return 0;
error_free_ffsm:
    kfree(ffsm);
error_free_mem:
    kfree(virt_mem);

    return -1;
}

static ssize_t ffs_epfile_iorw(struct file *file, struct ffs_io_data *io_data)
{
    struct ffs_epfile *epfile = file->private_data;
    struct usb_request *req = NULL;
    struct ffs_ep *ep = NULL;
    struct ffs_memory *ffsm = NULL;
    ssize_t ret, data_len = -EINVAL;
    int halt;

    /* Are we still active? */
    if (WARN_ON(epfile->ffs->state != FFS_ACTIVE))
        return -ENODEV;

    /* Wait for endpoint to be enabled */
    ep = epfile->ep;
    if (!ep) {
        if (file->f_flags & O_NONBLOCK)
            return -EAGAIN;

        ret = wait_event_interruptible(
                epfile->ffs->wait, (ep = epfile->ep));
        if (ret)
            return -EINTR;
    }

    /* Do we halt? */
    halt = (!io_data->read == !epfile->in);
    if (halt && epfile->isoc)
        return -EINVAL;

    /* We will be using request and read_buffer */
    ret = ffs_mutex_lock(&epfile->mutex, file->f_flags & O_NONBLOCK);
    if (unlikely(ret))
        goto error;

    /* Allocate & copy */
    if (!halt) {
        struct usb_gadget *gadget;
        /*
         * if we _do_ wait above, the epfile->ffs->gadget might be NULL
         * before the waiting completes, so do not assign to 'gadget'
         * earlier
         */
        gadget = epfile->ffs->gadget;

        spin_lock_irq(&epfile->ffs->eps_lock);
        /* In the meantime, endpoint got disabled or changed. */
        if (epfile->ep != ep) {
            ret = -ESHUTDOWN;
            goto error_lock;
        }
        data_len = io_data->len;
        /*
         * Controller may require buffer size to be aligned to
         * maxpacketsize of an out endpoint.
         */
        if (io_data->read)
            data_len = usb_ep_align_maybe(gadget, ep->ep, data_len);
        spin_unlock_irq(&epfile->ffs->eps_lock);
    }

    spin_lock_irq(&epfile->ffs->eps_lock);
    ffsm = generic_find_memory_area(epfile, io_data->buf, io_data->len);
    if (ffsm == NULL)
    {
        return -EFAULT;
    }
    if (epfile->ep != ep) {
        /* In the meantime, endpoint got disabled or changed. */
        ret = -ESHUTDOWN;
    }
    else if (halt) {
        ret = usb_ep_set_halt(ep->ep);
        if (!ret)
            ret = -EBADMSG;
    }
    else if (!io_data->aio) {
        DECLARE_COMPLETION_ONSTACK(done);
        bool interrupted = false;

        req = ep->req;
        req->buf      = (void *)(ffsm->mem + io_data->buf - ffsm->vm_start);
        req->length   = data_len;

        req->context  = &done;
        req->complete = ffs_epfile_io_complete;

        ret = usb_ep_queue(ep->ep, req, GFP_ATOMIC);
        if (unlikely(ret < 0))
            goto error_lock;

        spin_unlock_irq(&epfile->ffs->eps_lock);
        if (io_data->timeout > 0) {
            ret = wait_for_completion_interruptible_timeout(&done, io_data->timeout);
            if (ret < 0) {
                /*
                 * To avoid race condition with ffs_epfile_io_complete,
                 * dequeue the request first then check
                 * status. usb_ep_dequeue API should guarantee no race
                 * condition with req->complete callback.
                 */
                usb_ep_dequeue(ep->ep, req);
                wait_for_completion(&done);
                interrupted = ep->status < 0;
            } else if (ret == 0) {
                ret = -EBUSY;
                usb_ep_dequeue(ep->ep, req);
                wait_for_completion(&done);
                goto error_mutex;
            }
        } else {
            ret = wait_for_completion_interruptible(&done);
            if (ret < 0) {
                usb_ep_dequeue(ep->ep, req);
                wait_for_completion(&done);
                interrupted = ep->status < 0;
            }
        }

        if (interrupted) {
            ret = -EINTR;
        } else {
            ret = req->actual;
        }
        goto error_mutex;
    }
    else if (!(req = usb_ep_alloc_request(ep->ep, GFP_ATOMIC))) {
        ret = -ENOMEM;
    }
    else {
        req->buf     = (void *)(ffsm->mem + io_data->buf - ffsm->vm_start);
        req->length  = data_len;

        io_data->ep     = ep->ep;
        io_data->req    = req;
        io_data->epfile = epfile;

        req->context  = io_data;
        req->complete = ffs_epfile_async_io_complete;
        list_add(&req->list, &ep->req->list);
        ret = usb_ep_queue(ep->ep, req, GFP_ATOMIC);
        if (unlikely(ret)) {
            usb_ep_free_request(ep->ep, req);
            goto error_lock;
        }

        ret = -EIOCBQUEUED;
    }

error_lock:
    spin_unlock_irq(&epfile->ffs->eps_lock);
error_mutex:
    mutex_unlock(&epfile->mutex);
error:
    return ret;
}

static long ffs_epfile_ioctl(struct file *file, unsigned code, unsigned long value)
{
    struct ffs_epfile *epfile = file->private_data;
    struct ffs_ep *ep = epfile->ep;
    int ret = 0;
    struct generic_memory mem;
    struct ffs_memory *ffsm = NULL;

    ENTER();

    if (WARN_ON(epfile->ffs->state != FFS_ACTIVE))
        return -ENODEV;

    spin_lock_irq(&epfile->ffs->eps_lock);

    switch (code) {
    case FUNCTIONFS_ENDPOINT_QUEUE_INIT:
        ret = kfifo_alloc(&epfile->reqEventFifo, MAX_REQUEST * sizeof(struct UsbFnReqEvent), GFP_KERNEL);
        break;
    case FUNCTIONFS_ENDPOINT_QUEUE_DEL:
        kfifo_free(&epfile->reqEventFifo);
        break;
    case FUNCTIONFS_ENDPOINT_RELEASE_BUF:
        if (copy_from_user(&mem, (void __user *)value, sizeof(mem)))
        {
            pr_info("copy from user failed\n");
            return -EFAULT;
        }
        ffsm = generic_find_memory_area(epfile, mem.buf, mem.size);
        if (ffsm == NULL)
        {
            return -EFAULT;
        }
        list_del(&ffsm->memlist);
        kfree((void *)ffsm->mem);
        kfree(ffsm);
        break;
    case FUNCTIONFS_ENDPOINT_READ:
    case FUNCTIONFS_ENDPOINT_WRITE:
    {
        struct IoData myIoData;
        struct ffs_io_data io_data, *p = &io_data;
        ret = copy_from_user(&myIoData, (void __user *)value, sizeof(struct IoData));
        if (unlikely(ret)) {
            spin_unlock_irq(&epfile->ffs->eps_lock);
            return -EFAULT;
        }
        if (myIoData.aio) {
            p = kmalloc(sizeof(io_data), GFP_KERNEL);
            if (unlikely(!p)) {
                spin_unlock_irq(&epfile->ffs->eps_lock);
                return -ENOMEM;
            }
        } else {
            memset(p,  0, sizeof(*p));
        }
        memcpy(p, &myIoData, sizeof(struct IoData));

        spin_unlock_irq(&epfile->ffs->eps_lock);
        ret = ffs_epfile_iorw(file, p);
        if (ret == -EIOCBQUEUED) {
            return 0;
        }
        if (p->aio)
            kfree(p);
        return ret;
    }
    case FUNCTIONFS_ENDPOINT_RW_CANCEL:
    {
        struct usb_request *req;
        struct IoData myIoData;
        if (!ep) {
            spin_unlock_irq(&epfile->ffs->eps_lock);
            return -EFAULT;
        }
        ret = copy_from_user(&myIoData, (void __user *)value, sizeof(struct IoData));
        if (unlikely(ret)) {
            spin_unlock_irq(&epfile->ffs->eps_lock);
            return -EFAULT;
        }
        ffsm = generic_find_memory_area(epfile, myIoData.buf, myIoData.len);
        if (ffsm == NULL)
        {
            return -EFAULT;
        }
        list_for_each_entry(req, &epfile->ep->req->list, list) {
            if (req->buf == (void *)(ffsm->mem + myIoData.buf - ffsm->vm_start)) {
                usb_ep_dequeue(epfile->ep->ep, req);
                spin_unlock_irq(&epfile->ffs->eps_lock);
                return 0;
            }
        }
        spin_unlock_irq(&epfile->ffs->eps_lock);
        return -EFAULT;
    }
    case FUNCTIONFS_ENDPOINT_GET_REQ_STATUS:
    {
        struct usb_request *req;
        struct IoData myIoData;
        if (!ep) {
            spin_unlock_irq(&epfile->ffs->eps_lock);
            return -EFAULT;
        }
        ret = copy_from_user(&myIoData,(void __user *)value, sizeof(struct IoData));
        if (unlikely(ret)) {
            spin_unlock_irq(&epfile->ffs->eps_lock);
            return -EFAULT;
        }
        ffsm = generic_find_memory_area(epfile, myIoData.buf, myIoData.len);
        if (ffsm == NULL)
        {
            return -EFAULT;
        }
        list_for_each_entry(req, &epfile->ep->req->list, list) {
            if (req->buf == (void *)(ffsm->mem + myIoData.buf - ffsm->vm_start)) {
                spin_unlock_irq(&epfile->ffs->eps_lock);
                return req->status;
            }
        }
        spin_unlock_irq(&epfile->ffs->eps_lock);
        return -EFAULT;
    }
    case FUNCTIONFS_FIFO_STATUS:
        ret = usb_ep_fifo_status(epfile->ep->ep);
        break;
    case FUNCTIONFS_FIFO_FLUSH:
        usb_ep_fifo_flush(epfile->ep->ep);
        ret = 0;
        break;
    case FUNCTIONFS_CLEAR_HALT:
        ret = usb_ep_clear_halt(epfile->ep->ep);
        break;
    case FUNCTIONFS_ENDPOINT_REVMAP:
        ret = epfile->ep->num;
        break;
    case FUNCTIONFS_ENDPOINT_DESC:
    {
        int desc_idx;
        int i;
        struct usb_endpoint_descriptor *desc;

        switch (epfile->ffs->speed) {
        case USB_SPEED_SUPER:
            desc_idx = 2;
            break;
        case USB_SPEED_HIGH:
            desc_idx = 1;
            break;
        default:
            desc_idx = 1;
        }
        for (i = 0; i < epfile->ffs->eps_count; i++) {
            if (epfile->ffs->epfiles + i == epfile)
                break;
        }
        ep = epfile->ffs->eps + i;
        desc = ep->descs[desc_idx];
        spin_unlock_irq(&epfile->ffs->eps_lock);
        ret = copy_to_user((void __user *)value, desc, desc->bLength);
        if (ret)
            ret = -EFAULT;
        return ret;
    }
    default:
        ret = -ENOTTY;
    }
    spin_unlock_irq(&epfile->ffs->eps_lock);

    return ret;
}

static ssize_t ffs_epfile_read(struct file *file, char __user *buf, size_t count, loff_t *f_pos)
{
    int status = 0;
    unsigned int copied = 0;
    unsigned long flags;
    struct ffs_epfile *epfile = file->private_data;
    ENTER();
    if (kfifo_is_empty(&epfile->reqEventFifo)) {
        return 0;
    }
    spin_lock_irqsave(&epfile->ffs->eps_lock, flags);
    status = kfifo_to_user(&epfile->reqEventFifo, buf, count, &copied) == 0 ? copied : -1;
    spin_unlock_irqrestore(&epfile->ffs->eps_lock, flags);

    return status;
}

static ssize_t ffs_epfile_write(struct file *file, const char __user *buf, size_t count, loff_t *f_pos)
{
    return count;
}

static unsigned int ffs_epfile_poll(struct file *file, struct poll_table_struct * wait)
{
    unsigned int mask = 0;
    struct ffs_epfile *epfile = file->private_data;
    ENTER();
    poll_wait(file, &epfile->wait_que, wait);
    if (!kfifo_is_empty(&epfile->reqEventFifo)) {
        mask |= POLLIN;
    }
    return mask;
}

#ifdef CONFIG_COMPAT
static long ffs_epfile_compat_ioctl(struct file *file, unsigned code,
        unsigned long value)
{
    return ffs_epfile_ioctl(file, code, value);
}
#endif

static const struct file_operations ffs_epfile_operations = {
    .owner   = THIS_MODULE,
    .llseek =    no_llseek,
    .mmap = ffs_epfile_mmap,
    .read    = ffs_epfile_read,
    .write   = ffs_epfile_write,
    .poll = ffs_epfile_poll,
    .open =        ffs_epfile_open,
    .release =    ffs_epfile_release,
    .unlocked_ioctl =    ffs_epfile_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl = ffs_epfile_compat_ioctl,
#endif
};

/* ffs_data and ffs_function construction and destruction code **************/
static void ffs_data_clear(struct ffs_data *ffs);
static void ffs_data_reset(struct ffs_data *ffs);
static dev_t g_dev;
#define MAX_EP_DEV 10
static long usbfn_ioctl(struct file *file, unsigned int cmd, unsigned long value)
{
    long ret;
    ENTER();
    switch(cmd)
    {
        case FUNCTIONFS_NEWFN:
        {
            struct ffs_dev *ffs_dev;
            struct ffs_data    *ffs;
            struct FuncNew newfn;
            char nameEp0[MAX_NAMELEN];
            ret = copy_from_user(&newfn, (void __user *)value, sizeof(struct FuncNew ));
            if (unlikely(ret)) {
                return -EFAULT;
            }
            ffs = ffs_data_new(newfn.name);
            if (unlikely(!ffs)) {
                return (-ENOMEM);
            }

            if (newfn.nameLen > MAX_NAMELEN) {
                return -EPERM;
            }
            memcpy(ffs->dev_name, newfn.name, newfn.nameLen);

            if (unlikely(!ffs->dev_name)) {
                ffs_data_put(ffs);
                return (-ENOMEM);
            }

            if (sprintf(nameEp0, "%s.ep%u", ffs->dev_name, 0) < 0) {
                ffs_data_put(ffs);
                return -EFAULT;
            }
            ffs_dev = ffs_acquire_dev(newfn.name);
            if (IS_ERR(ffs_dev)) {
                ffs_data_put(ffs);
                return (-ENODEV);
            }
            ffs->private_data = ffs_dev;

            ret = alloc_chrdev_region(&g_dev, 0, MAX_EP_DEV, nameEp0);
            if (ret < 0) {
                ffs_release_dev(ffs);
                ffs_data_put(ffs);
                return -EBUSY;
            }
            cdev_init(&ffs->cdev, &ffs_ep0_operations);
            ffs->devno = MKDEV(MAJOR(g_dev), 0);
            ret = cdev_add(&ffs->cdev, ffs->devno, 1);
            if (ret) {
                ffs_release_dev(ffs);
                ffs_data_put(ffs);
                return -EBUSY;
            }

            ffs->fn_device = device_create(ffs_class, NULL, ffs->devno, NULL, nameEp0);
            if (IS_ERR(ffs->fn_device)) {
                cdev_del(&ffs->cdev);
                ffs_release_dev(ffs);
                ffs_data_put(ffs);
                return -EBUSY;
            }
            return 0;
        }
        case FUNCTIONFS_DELFN:
        {
            struct FuncNew newfn;
            struct ffs_data    *ffs;
            struct ffs_dev *ffs_dev;
            ret = copy_from_user(&newfn, (void __user *)value, sizeof(struct FuncNew ));
            if (unlikely(ret)) {
                return -EFAULT;
            }

            ffs_dev = _ffs_find_dev(newfn.name);
            if (IS_ERR(ffs_dev)) {
                return -EFAULT;
            }
            ffs = ffs_dev->ffs_data;
            device_destroy(ffs_class, ffs->devno);
            cdev_del(&ffs->cdev);
            unregister_chrdev_region(g_dev, MAX_EP_DEV);
            ffs_release_dev(ffs);
            ffs_data_clear(ffs);
            destroy_workqueue(ffs->io_completion_wq);
            kfree(ffs);
            return 0;
        }
        default:
            ret = -ENOTTY;
        }

    return ret;
}

static int usbfn_open(struct inode *inode, struct file *file)
{
    return 0;
}

static int usbfn_release(struct inode *inode, struct file *file)
{
    return 0;
}

static struct file_operations usbfn_fops = {
    .owner   = THIS_MODULE,
    .unlocked_ioctl   = usbfn_ioctl,
    .open    = usbfn_open,
    .release = usbfn_release,
#ifdef CONFIG_COMPAT
    .compat_ioctl = usbfn_ioctl,
#endif
};

static struct miscdevice usbfn_misc = {
    .minor = MISC_DYNAMIC_MINOR,
    .name = "usbfn",
    .fops = &usbfn_fops,
};

/* Driver's main init/cleanup functions *************************************/
static int functionfs_init(void)
{
    int ret;

    ENTER();
    ret = misc_register(&usbfn_misc);
    if (likely(!ret))
        pr_info("file system registered\n");
    else
        pr_err("failed registering file system (%d)\n", ret);

    //ffs_class = class_create(THIS_MODULE, "functionfs");
    ffs_class = class_create("functionfs");
    if (IS_ERR(ffs_class))
        return PTR_ERR(ffs_class);

    ffs_class->devnode = ffs_devnode;

    return ret;
}

static void functionfs_cleanup(void)
{
    ENTER();
    class_destroy(ffs_class);
    misc_deregister(&usbfn_misc);
}

static void ffs_data_get(struct ffs_data *ffs)
{
    ENTER();
    refcount_inc(&ffs->ref);
}

static void ffs_data_put(struct ffs_data *ffs)
{
    ENTER();
    if (unlikely(refcount_dec_and_test(&ffs->ref))) {
        pr_info("%s(): freeing\n", __func__);
        ffs_data_clear(ffs);
        BUG_ON(waitqueue_active(&ffs->ev.waitq) ||
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,0,0)
            swait_active(&ffs->ep0req_completion.wait) ||
#else
            waitqueue_active(&ffs->ep0req_completion.wait) ||
#endif
               waitqueue_active(&ffs->wait) ||
               waitqueue_active(&ffs->wait_que));
        destroy_workqueue(ffs->io_completion_wq);
        kfree(ffs);
    }
}

static struct ffs_data *ffs_data_new(const char *dev_name)
{
    struct ffs_data *ffs = kzalloc(sizeof *ffs, GFP_KERNEL);
    if (unlikely(!ffs))
        return NULL;

    ENTER();

    ffs->io_completion_wq = alloc_ordered_workqueue("%s", 0, dev_name);
    if (!ffs->io_completion_wq) {
        kfree(ffs);
        return NULL;
    }

    refcount_set(&ffs->ref, 1);
    atomic_set(&ffs->opened, 0);
    ffs->state = FFS_READ_DESCRIPTORS;
    mutex_init(&ffs->mutex);
    spin_lock_init(&ffs->eps_lock);
    spin_lock_init(&ffs->mem_lock);
    init_waitqueue_head(&ffs->ev.waitq);
    init_waitqueue_head(&ffs->wait);
    init_waitqueue_head(&ffs->wait_que);
    init_completion(&ffs->ep0req_completion);
    INIT_LIST_HEAD(&ffs->memory_list);
    ffs->ev.can_stall = 1;

    return ffs;
}

static void ffs_data_clear(struct ffs_data *ffs)
{
    ENTER();

    ffs_closed(ffs);

    BUG_ON(ffs->gadget);

    if (ffs->epfiles)
        ffs_epfiles_destroy(ffs->epfiles, ffs->eps_count);

    if (ffs->ffs_eventfd)
        eventfd_ctx_put(ffs->ffs_eventfd);

    kfree(ffs->raw_descs_data);
    kfree(ffs->raw_strings);
    kfree(ffs->stringtabs);
}

static void ffs_data_reset(struct ffs_data *ffs)
{
    ENTER();

    ffs_data_clear(ffs);

    ffs->epfiles = NULL;
    ffs->raw_descs_data = NULL;
    ffs->raw_descs = NULL;
    ffs->raw_strings = NULL;
    ffs->stringtabs = NULL;

    ffs->raw_descs_length = 0;
    ffs->fs_descs_count = 0;
    ffs->hs_descs_count = 0;
    ffs->ss_descs_count = 0;

    ffs->strings_count = 0;
    ffs->interfaces_count = 0;
    ffs->eps_count = 0;

    ffs->ev.count = 0;

    ffs->state = FFS_READ_DESCRIPTORS;
    ffs->setup_state = FFS_NO_SETUP;
    ffs->flags = 0;
}

static int functionfs_bind(struct ffs_data *ffs, struct usb_composite_dev *cdev)
{
    struct usb_gadget_strings **lang;
    int first_id;

    ENTER();

    if (WARN_ON(ffs->state != FFS_ACTIVE
         || test_and_set_bit(FFS_FL_BOUND, &ffs->flags)))
        return -EBADFD;

    first_id = usb_string_ids_n(cdev, ffs->strings_count);
    if (unlikely(first_id < 0))
        return first_id;

    ffs->ep0req = usb_ep_alloc_request(cdev->gadget->ep0, GFP_KERNEL);
    if (unlikely(!ffs->ep0req))
        return -ENOMEM;
    ffs->ep0req->complete = ffs_ep0_complete;
    ffs->ep0req->context = ffs;
    INIT_LIST_HEAD(&ffs->ep0req->list);

    lang = ffs->stringtabs;
    if (lang) {
        for (; *lang; ++lang) {
            struct usb_string *str = (*lang)->strings;
            int id = first_id;
            for (; str->s; ++id, ++str)
                str->id = id;
        }
    }

    ffs->gadget = cdev->gadget;
    ffs->speed = cdev->gadget->speed;
    ffs_data_get(ffs);
    return 0;
}

static void functionfs_unbind(struct ffs_data *ffs)
{
    ENTER();

    if (!WARN_ON(!ffs->gadget)) {
        usb_ep_free_request(ffs->gadget->ep0, ffs->ep0req);
        ffs->ep0req = NULL;
        ffs->gadget = NULL;
        clear_bit(FFS_FL_BOUND, &ffs->flags);
        ffs_data_put(ffs);
    }
}

static int ffs_epfiles_create(struct ffs_data *ffs)
{
    struct ffs_epfile *epfile = NULL, *epfiles = NULL;
    unsigned int i, count ,ret;

    ENTER();

    count = ffs->eps_count;
    epfiles = kcalloc(count, sizeof(*epfiles), GFP_KERNEL);
    if (!epfiles)
        return -ENOMEM;

    epfile = epfiles;
    for (i = 1; i <= count; ++i, ++epfile) {
        epfile->ffs = ffs;
        mutex_init(&epfile->mutex);
        INIT_LIST_HEAD(&epfile->memory_list);
        init_waitqueue_head(&epfile->wait_que);
        if (ffs->user_flags & FUNCTIONFS_VIRTUAL_ADDR) {
            if (sprintf(epfile->name, "%s.ep%02x", ffs->dev_name, ffs->eps_addrmap[i]) < 0) {
                return -EFAULT;
            }
        } else {
            if (sprintf(epfile->name, "%s.ep%u", ffs->dev_name, i) < 0) {
                return -EFAULT;
            }
        }

        cdev_init(&epfile->cdev, &ffs_epfile_operations);
        epfile->devno=MKDEV(MAJOR(ffs->devno), i);
        ret = cdev_add(&epfile->cdev, epfile->devno, 1);
        if (ret)
        {
            ffs_epfiles_destroy(epfiles, i - 1);
            return -EBUSY;
        }

        epfile->device = device_create(ffs_class, NULL, epfile->devno, NULL, epfile->name);
        if (IS_ERR(epfile->device))
        {
            cdev_del(&epfile->cdev);
            ffs_epfiles_destroy(epfiles, i - 1);
            return -EBUSY;
        }
    }

    ffs->epfiles = epfiles;
    return 0;
}

static void ffs_epfiles_destroy(struct ffs_epfile *epfiles, unsigned count)
{
    struct ffs_epfile *epfile = epfiles;

    ENTER();

    for (; count; --count, ++epfile) {
        BUG_ON(mutex_is_locked(&epfile->mutex));
        device_destroy(ffs_class, epfile->devno);
        cdev_del(&epfile->cdev);
    }

    kfree(epfiles);
}

static void ffs_func_eps_disable(struct ffs_function *func)
{
    struct ffs_ep *ep         = func->eps;
    struct ffs_epfile *epfile = func->ffs->epfiles;
    unsigned count            = func->ffs->eps_count;
    unsigned long flags;

    spin_lock_irqsave(&func->ffs->eps_lock, flags);
    while (count--) {
        /* pending requests get nuked */
        if (likely(ep->ep))
            usb_ep_disable(ep->ep);
        ++ep;

        if (epfile) {
            epfile->ep = NULL;
            ++epfile;
        }
    }
    spin_unlock_irqrestore(&func->ffs->eps_lock, flags);
}

static int ffs_func_eps_enable(struct ffs_function *func)
{
    struct ffs_data *ffs      = func->ffs;
    struct ffs_ep *ep         = func->eps;
    struct ffs_epfile *epfile = ffs->epfiles;
    unsigned count            = ffs->eps_count;
    unsigned long flags;
    int ret = 0;

    spin_lock_irqsave(&func->ffs->eps_lock, flags);
    while(count--) {
        ep->ep->driver_data = ep;

        ret = config_ep_by_speed(func->gadget, &func->function, ep->ep);
        if (ret) {
            pr_err("%s: config_ep_by_speed(%s) returned %d\n",
                    __func__, ep->ep->name, ret);
            break;
        }

        ret = usb_ep_enable(ep->ep);
        if (likely(!ret)) {
            epfile->ep = ep;
            epfile->in = usb_endpoint_dir_in(ep->ep->desc);
            epfile->isoc = usb_endpoint_xfer_isoc(ep->ep->desc);
        } else {
            break;
        }

        ++ep;
        ++epfile;
    }

    wake_up_interruptible(&ffs->wait);
    spin_unlock_irqrestore(&func->ffs->eps_lock, flags);

    return ret;
}

/* Parsing and building descriptors and strings *****************************/

/*
 * This validates if data pointed by data is a valid USB descriptor as
 * well as record how many interfaces, endpoints and strings are
 * required by given configuration.  Returns address after the
 * descriptor or NULL if data is invalid.
 */
enum ffs_entity_type {
    FFS_DESCRIPTOR, FFS_INTERFACE, FFS_STRING, FFS_ENDPOINT
};

enum ffs_os_desc_type {
    FFS_OS_DESC, FFS_OS_DESC_EXT_COMPAT, FFS_OS_DESC_EXT_PROP
};

typedef int (*ffs_entity_callback)(enum ffs_entity_type entity, u8 *valuep,
                struct usb_descriptor_header *desc,
                void *priv);

typedef int (*ffs_os_desc_callback)(enum ffs_os_desc_type entity,
                struct usb_os_desc_header *h, void *data,
                unsigned len, void *priv);

static int __must_check ffs_do_single_desc(char *data, unsigned len,
                ffs_entity_callback entity,
                void *priv)
{
    struct usb_descriptor_header *_ds = (void *)data;
    u8 length;
    int ret;

    ENTER();

    /* At least two bytes are required: length and type */
    if (len < 2) {
        pr_vdebug("descriptor too short\n");
        return -EINVAL;
    }

    /* If we have at least as many bytes as the descriptor takes? */
    length = _ds->bLength;
    if (len < length) {
        pr_vdebug("descriptor longer then available data\n");
        return -EINVAL;
    }

#define __entity_check_INTERFACE(val)  1
#define __entity_check_STRING(val)     (val)
#define __entity_check_ENDPOINT(val)   ((val) & USB_ENDPOINT_NUMBER_MASK)
#define __entity(type, val) do {                    \
        pr_vdebug("entity " #type "(%02x)\n", (val));        \
        if (unlikely(!__entity_check_ ##type(val))) {        \
            pr_vdebug("invalid entity's value\n");        \
            return -EINVAL;                    \
        }                            \
        ret = entity(FFS_ ##type, &val, _ds, priv);        \
        if (unlikely(ret < 0)) {                \
            pr_debug("entity " #type "(%02x); ret = %d\n",    \
                 (val), ret);                \
            return ret;                    \
        }                            \
    } while (0)

    /* Parse descriptor depending on type. */
    switch (_ds->bDescriptorType) {
    case USB_DT_DEVICE:
    case USB_DT_CONFIG:
    case USB_DT_STRING:
    case USB_DT_DEVICE_QUALIFIER:
        /* function can't have any of those */
        pr_vdebug("descriptor reserved for gadget: %d\n",
              _ds->bDescriptorType);
        return -EINVAL;

    case USB_DT_INTERFACE: {
        struct usb_interface_descriptor *ds = (void *)_ds;
        pr_vdebug("interface descriptor\n");
        if (length != sizeof *ds)
            goto inv_length;

        __entity(INTERFACE, ds->bInterfaceNumber);
        if (ds->iInterface)
            __entity(STRING, ds->iInterface);
    }
        break;

    case USB_DT_ENDPOINT: {
        struct usb_endpoint_descriptor *ds = (void *)_ds;
        pr_vdebug("endpoint descriptor\n");
        if (length != USB_DT_ENDPOINT_SIZE &&
            length != USB_DT_ENDPOINT_AUDIO_SIZE)
            goto inv_length;
        __entity(ENDPOINT, ds->bEndpointAddress);
    }
        break;

    case HID_DT_HID:
        pr_vdebug("hid descriptor\n");
        if (length != sizeof(struct hid_descriptor))
            goto inv_length;
        break;

    case USB_DT_OTG:
        if (length != sizeof(struct usb_otg_descriptor))
            goto inv_length;
        break;

    case USB_DT_INTERFACE_ASSOCIATION: {
        struct usb_interface_assoc_descriptor *ds = (void *)_ds;
        pr_vdebug("interface association descriptor\n");
        if (length != sizeof *ds)
            goto inv_length;
        if (ds->iFunction)
            __entity(STRING, ds->iFunction);
    }
        break;

    case USB_DT_SS_ENDPOINT_COMP:
        pr_vdebug("EP SS companion descriptor\n");
        if (length != sizeof(struct usb_ss_ep_comp_descriptor))
            goto inv_length;
        break;

    case USB_DT_OTHER_SPEED_CONFIG:
    case USB_DT_INTERFACE_POWER:
    case USB_DT_DEBUG:
    case USB_DT_SECURITY:
    case USB_DT_CS_RADIO_CONTROL:
        pr_vdebug("unimplemented descriptor: %d\n", _ds->bDescriptorType);
        break;
    default:
        /* We should never be here */
        pr_vdebug("unknown descriptor: %d\n", _ds->bDescriptorType);
        break;
inv_length:
        pr_vdebug("invalid length: %d (descriptor %d)\n",
              _ds->bLength, _ds->bDescriptorType);
        return -EINVAL;
    }

#undef __entity
#undef __entity_check_DESCRIPTOR
#undef __entity_check_INTERFACE
#undef __entity_check_STRING
#undef __entity_check_ENDPOINT

    return length;
}

static int __must_check ffs_do_descs(unsigned count, char *data, unsigned len,
                ffs_entity_callback entity, void *priv)
{
    const unsigned _len = len;
    uintptr_t num = 0;

    ENTER();

    for (;;) {
        int ret;

        if (num == count)
            data = NULL;

        /* Record "descriptor" entity */
        ret = entity(FFS_DESCRIPTOR, (u8 *)num, (void *)data, priv);
        if (unlikely(ret < 0)) {
            pr_debug("entity DESCRIPTOR(%02lx); ret = %d\n",
                 num, ret);
            return ret;
        }

        if (!data)
            return _len - len;

        ret = ffs_do_single_desc(data, len, entity, priv);
        if (unlikely(ret < 0)) {
            pr_debug("%s returns %d\n", __func__, ret);
            return ret;
        }

        len -= ret;
        data += ret;
        ++num;
    }
}

static int __ffs_data_do_entity(enum ffs_entity_type type,
                u8 *valuep, struct usb_descriptor_header *desc,
                void *priv)
{
    struct ffs_desc_helper *helper = priv;
    struct usb_endpoint_descriptor *d = NULL;

    ENTER();

    switch (type) {
    case FFS_DESCRIPTOR:
        break;

    case FFS_INTERFACE:
        /*
         * Interfaces are indexed from zero so if we
         * encountered interface "n" then there are at least
         * "n+1" interfaces.
         */
        if (*valuep >= helper->interfaces_count)
            helper->interfaces_count = *valuep + 1;
        break;

    case FFS_STRING:
        /*
         * Strings are indexed from 1 (0 is reserved
         * for languages list)
         */
        if (*valuep > helper->ffs->strings_count)
            helper->ffs->strings_count = *valuep;
        break;

    case FFS_ENDPOINT:
        d = (void *)desc;
        helper->eps_count++;
        if (helper->eps_count >= FFS_MAX_EPS_COUNT)
            return -EINVAL;
        /* Check if descriptors for any speed were already parsed */
        if (!helper->ffs->eps_count && !helper->ffs->interfaces_count)
            helper->ffs->eps_addrmap[helper->eps_count] =
                d->bEndpointAddress;
        else if (helper->ffs->eps_addrmap[helper->eps_count] !=
                d->bEndpointAddress)
            return -EINVAL;
        break;
    }

    return 0;
}

static int __ffs_do_os_desc_header(enum ffs_os_desc_type *next_type,
                struct usb_os_desc_header *desc)
{
    u16 bcd_version = le16_to_cpu(desc->bcdVersion);
    u16 w_index = le16_to_cpu(desc->wIndex);

    if (bcd_version != 1) {
        pr_vdebug("unsupported os descriptors version: %d",
              bcd_version);
        return -EINVAL;
    }
    switch (w_index) {
    case 0x4:
        *next_type = FFS_OS_DESC_EXT_COMPAT;
        break;
    case 0x5:
        *next_type = FFS_OS_DESC_EXT_PROP;
        break;
    default:
        pr_vdebug("unsupported os descriptor type: %d", w_index);
        return -EINVAL;
    }

    return sizeof(*desc);
}

/*
 * Process all extended compatibility/extended property descriptors
 * of a feature descriptor
 */
static int __must_check ffs_do_single_os_desc(char *data, unsigned len,
                enum ffs_os_desc_type type,
                u16 feature_count,
                ffs_os_desc_callback entity,
                void *priv,
                struct usb_os_desc_header *h)
{
    int ret;
    const unsigned _len = len;

    ENTER();

    /* loop over all ext compat/ext prop descriptors */
    while (feature_count--) {
        ret = entity(type, h, data, len, priv);
        if (unlikely(ret < 0)) {
            pr_debug("bad OS descriptor, type: %d\n", type);
            return ret;
        }
        data += ret;
        len -= ret;
    }
    return _len - len;
}

/* Process a number of complete Feature Descriptors (Ext Compat or Ext Prop) */
static int __must_check ffs_do_os_descs(unsigned count,
                char *data, unsigned len,
                ffs_os_desc_callback entity, void *priv)
{
    const unsigned _len = len;
    unsigned long num = 0;

    ENTER();

    for (num = 0; num < count; ++num) {
        int ret;
        enum ffs_os_desc_type type;
        u16 feature_count;
        struct usb_os_desc_header *desc = (void *)data;

        if (len < sizeof(*desc))
            return -EINVAL;

        /*
         * Record "descriptor" entity.
         * Process dwLength, bcdVersion, wIndex, get b/wCount.
         * Move the data pointer to the beginning of extended
         * compatibilities proper or extended properties proper
         * portions of the data
         */
        if (le32_to_cpu(desc->dwLength) > len)
            return -EINVAL;

        ret = __ffs_do_os_desc_header(&type, desc);
        if (unlikely(ret < 0)) {
            pr_debug("entity OS_DESCRIPTOR(%02lx); ret = %d\n",
                 num, ret);
            return ret;
        }
        /*
         * 16-bit hex "?? 00" Little Endian looks like 8-bit hex "??"
         */
        feature_count = le16_to_cpu(desc->wCount);
        if (type == FFS_OS_DESC_EXT_COMPAT &&
            (feature_count > 255 || desc->Reserved))
                return -EINVAL;
        len -= ret;
        data += ret;

        /*
         * Process all function/property descriptors
         * of this Feature Descriptor
         */
        ret = ffs_do_single_os_desc(data, len, type,
                        feature_count, entity, priv, desc);
        if (unlikely(ret < 0)) {
            pr_debug("%s returns %d\n", __func__, ret);
            return ret;
        }

        len -= ret;
        data += ret;
    }
    return _len - len;
}

/**
 * Validate contents of the buffer from userspace related to OS descriptors.
 */
static int __ffs_data_do_os_desc(enum ffs_os_desc_type type,
                 struct usb_os_desc_header *h, void *data,
                 unsigned len, void *priv)
{
    struct ffs_data *ffs = priv;
    u8 length;

    ENTER();

    switch (type) {
    case FFS_OS_DESC_EXT_COMPAT: {
        struct usb_ext_compat_desc *d = data;
        int i;

        if (len < sizeof(*d) ||
            d->bFirstInterfaceNumber >= ffs->interfaces_count)
            return -EINVAL;
        if (d->Reserved1 != 1) {
            /*
             * According to the spec, Reserved1 must be set to 1
             * but older kernels incorrectly rejected non-zero
             * values.  We fix it here to avoid returning EINVAL
             * in response to values we used to accept.
             */
            pr_debug("usb_ext_compat_desc::Reserved1 forced to 1\n");
            d->Reserved1 = 1;
        }
        for (i = 0; i < ARRAY_SIZE(d->Reserved2); ++i)
            if (d->Reserved2[i])
                return -EINVAL;

        length = sizeof(struct usb_ext_compat_desc);
    }
        break;
    case FFS_OS_DESC_EXT_PROP: {
        struct usb_ext_prop_desc *d = data;
        u32 type, pdl;
        u16 pnl;

        if (len < sizeof(*d) || h->interface >= ffs->interfaces_count)
            return -EINVAL;
        length = le32_to_cpu(d->dwSize);
        if (len < length)
            return -EINVAL;
        type = le32_to_cpu(d->dwPropertyDataType);
        if (type < USB_EXT_PROP_UNICODE ||
            type > USB_EXT_PROP_UNICODE_MULTI) {
            pr_vdebug("unsupported os descriptor property type: %d",
                  type);
            return -EINVAL;
        }
        pnl = le16_to_cpu(d->wPropertyNameLength);
        if (length < 14 + pnl) {
            pr_vdebug("invalid os descriptor length: %d pnl:%d (descriptor %d)\n",
                  length, pnl, type);
            return -EINVAL;
        }
        pdl = le32_to_cpu(*(__le32 *)((u8 *)data + 10 + pnl));
        if (length != 14 + pnl + pdl) {
            pr_vdebug("invalid os descriptor length: %d pnl:%d pdl:%d (descriptor %d)\n",
                  length, pnl, pdl, type);
            return -EINVAL;
        }
        ++ffs->ms_os_descs_ext_prop_count;
        /* property name reported to the host as "WCHAR"s */
        ffs->ms_os_descs_ext_prop_name_len += pnl * 2;
        ffs->ms_os_descs_ext_prop_data_len += pdl;
    }
        break;
    default:
        pr_vdebug("unknown descriptor: %d\n", type);
        return -EINVAL;
    }
    return length;
}

static int __ffs_data_got_descs(struct ffs_data *ffs,
                char *const _data, size_t len)
{
    char *data = _data, *raw_descs = NULL;
    unsigned os_descs_count = 0, counts[3], flags;
    int ret = -EINVAL, i;
    struct ffs_desc_helper helper;

    ENTER();

    if (get_unaligned_le32(data + 4) != len)
        goto error;

    switch (get_unaligned_le32(data)) {
    case FUNCTIONFS_DESCRIPTORS_MAGIC:
        flags = FUNCTIONFS_HAS_FS_DESC | FUNCTIONFS_HAS_HS_DESC;
        data += 8;
        len  -= 8;
        break;
    case FUNCTIONFS_DESCRIPTORS_MAGIC_V2:
        flags = get_unaligned_le32(data + 8);
        ffs->user_flags = flags;
        if (flags & ~(FUNCTIONFS_HAS_FS_DESC |
                  FUNCTIONFS_HAS_HS_DESC |
                  FUNCTIONFS_HAS_SS_DESC |
                  FUNCTIONFS_HAS_MS_OS_DESC |
                  FUNCTIONFS_VIRTUAL_ADDR |
                  FUNCTIONFS_EVENTFD |
                  FUNCTIONFS_ALL_CTRL_RECIP |
                  FUNCTIONFS_CONFIG0_SETUP)) {
            ret = -ENOSYS;
            goto error;
        }
        data += 12;
        len  -= 12;
        break;
    default:
        goto error;
    }

    if (flags & FUNCTIONFS_EVENTFD) {
        if (len < 4)
            goto error;
        ffs->ffs_eventfd =
            eventfd_ctx_fdget((int)get_unaligned_le32(data));
        if (IS_ERR(ffs->ffs_eventfd)) {
            ret = PTR_ERR(ffs->ffs_eventfd);
            ffs->ffs_eventfd = NULL;
            goto error;
        }
        data += 4;
        len  -= 4;
    }

    /* Read fs_count, hs_count and ss_count (if present) */
    for (i = 0; i < 3; ++i) {
        if (!(flags & (1 << i))) {
            counts[i] = 0;
        } else if (len < 4) {
            goto error;
        } else {
            counts[i] = get_unaligned_le32(data);
            data += 4;
            len  -= 4;
        }
    }
    if (flags & (1 << i)) {
        if (len < 4) {
            goto error;
        }
        os_descs_count = get_unaligned_le32(data);
        data += 4;
        len -= 4;
    }

    /* Read descriptors */
    raw_descs = data;
    helper.ffs = ffs;
    for (i = 0; i < 3; ++i) {
        if (!counts[i])
            continue;
        helper.interfaces_count = 0;
        helper.eps_count = 0;
        ret = ffs_do_descs(counts[i], data, len,
                   __ffs_data_do_entity, &helper);
        if (ret < 0)
            goto error;
        if (!ffs->eps_count && !ffs->interfaces_count) {
            ffs->eps_count = helper.eps_count;
            ffs->interfaces_count = helper.interfaces_count;
        } else {
            if (ffs->eps_count != helper.eps_count) {
                ret = -EINVAL;
                goto error;
            }
            if (ffs->interfaces_count != helper.interfaces_count) {
                ret = -EINVAL;
                goto error;
            }
        }
        data += ret;
        len  -= ret;
    }
    if (os_descs_count) {
        ret = ffs_do_os_descs(os_descs_count, data, len,
                      __ffs_data_do_os_desc, ffs);
        if (ret < 0)
            goto error;
        data += ret;
        len -= ret;
    }

    if (raw_descs == data || len) {
        ret = -EINVAL;
        goto error;
    }

    ffs->raw_descs_data    = _data;
    ffs->raw_descs        = raw_descs;
    ffs->raw_descs_length    = data - raw_descs;
    ffs->fs_descs_count    = counts[0];
    ffs->hs_descs_count    = counts[1];
    ffs->ss_descs_count    = counts[2];
    ffs->ms_os_descs_count    = os_descs_count;

    return 0;

error:
    kfree(_data);
    return ret;
}

static int __ffs_data_got_strings(struct ffs_data *ffs,
                char *const _data, size_t len)
{
    u32 str_count, needed_count, lang_count;
    struct usb_gadget_strings **stringtabs = NULL, *t = NULL;
    const char *data = _data;
    struct usb_string *s = NULL;

    ENTER();

    if (unlikely(len < 16 ||
             get_unaligned_le32(data) != FUNCTIONFS_STRINGS_MAGIC ||
             get_unaligned_le32(data + 4) != len))
        goto error;
    str_count  = get_unaligned_le32(data + 8);
    lang_count = get_unaligned_le32(data + 12);

    /* if one is zero the other must be zero */
    if (unlikely(!str_count != !lang_count))
        goto error;

    /* Do we have at least as many strings as descriptors need? */
    needed_count = ffs->strings_count;
    if (unlikely(str_count < needed_count))
        goto error;

    /*
     * If we don't need any strings just return and free all
     * memory.
     */
    if (!needed_count) {
        kfree(_data);
        return 0;
    }

    /* Allocate everything in one chunk so there's less maintenance. */
    {
        unsigned i = 0;
        vla_group(d);
        vla_item(d, struct usb_gadget_strings *, stringtabs,
            lang_count + 1);
        vla_item(d, struct usb_gadget_strings, stringtab, lang_count);
        vla_item(d, struct usb_string, strings,
            lang_count*(needed_count+1));

        char *vlabuf = kmalloc(vla_group_size(d), GFP_KERNEL);

        if (unlikely(!vlabuf)) {
            kfree(_data);
            return -ENOMEM;
        }

        /* Initialize the VLA pointers */
        stringtabs = vla_ptr(vlabuf, d, stringtabs);
        t = vla_ptr(vlabuf, d, stringtab);
        i = lang_count;
        do {
            *stringtabs++ = t++;
        } while (--i);
        *stringtabs = NULL;

        /* stringtabs = vlabuf = d_stringtabs for later kfree */
        stringtabs = vla_ptr(vlabuf, d, stringtabs);
        t = vla_ptr(vlabuf, d, stringtab);
        s = vla_ptr(vlabuf, d, strings);
    }

    /* For each language */
    data += 16;
    len -= 16;

    do { /* lang_count > 0 so we can use do-while */
        unsigned needed = needed_count;

        if (unlikely(len < 3))
            goto error_free;
        t->language = get_unaligned_le16(data);
        t->strings  = s;
        ++t;

        data += 2;
        len -= 2;

        /* For each string */
        do { /* str_count > 0 so we can use do-while */
            size_t length = strnlen(data, len);

            if (unlikely(length == len))
                goto error_free;

            /*
             * User may provide more strings then we need,
             * if that's the case we simply ignore the
             * rest
             */
            if (likely(needed)) {
                /*
                 * s->id will be set while adding
                 * function to configuration so for
                 * now just leave garbage here.
                 */
                s->s = data;
                --needed;
                ++s;
            }

            data += length + 1;
            len -= length + 1;
        } while (--str_count);

        s->id = 0;   /* terminator */
        s->s = NULL;
        ++s;

    } while (--lang_count);

    /* Some garbage left? */
    if (unlikely(len))
        goto error_free;

    /* Done! */
    ffs->stringtabs = stringtabs;
    ffs->raw_strings = _data;

    return 0;

error_free:
    kfree(stringtabs);
error:
    kfree(_data);
    return -EINVAL;
}

/* Events handling and management *******************************************/
static void __ffs_event_add(struct ffs_data *ffs,
                enum usb_functionfs_event_type type)
{
    enum usb_functionfs_event_type rem_type1, rem_type2 = type;
    int neg = 0;

    /*
     * Abort any unhandled setup
     *
     * We do not need to worry about some cmpxchg() changing value
     * of ffs->setup_state without holding the lock because when
     * state is FFS_SETUP_PENDING cmpxchg() in several places in
     * the source does nothing.
     */
    if (ffs->setup_state == FFS_SETUP_PENDING)
        ffs->setup_state = FFS_SETUP_CANCELLED;

    /*
     * Logic of this function guarantees that there are at most four pending
     * evens on ffs->ev.types queue.  This is important because the queue
     * has space for four elements only and __ffs_ep0_read_events function
     * depends on that limit as well.  If more event types are added, those
     * limits have to be revisited or guaranteed to still hold.
     */
    switch (type) {
    case FUNCTIONFS_RESUME:
        rem_type2 = FUNCTIONFS_SUSPEND;
        /* FALL THROUGH */
    case FUNCTIONFS_SUSPEND:
    case FUNCTIONFS_SETUP:
        rem_type1 = type;
        /* Discard all similar events */
        break;

    case FUNCTIONFS_BIND:
    case FUNCTIONFS_UNBIND:
    case FUNCTIONFS_DISABLE:
    case FUNCTIONFS_ENABLE:
        /* Discard everything other then power management. */
        rem_type1 = FUNCTIONFS_SUSPEND;
        rem_type2 = FUNCTIONFS_RESUME;
        neg = 1;
        break;

    default:
        WARN(1, "%d: unknown event, this should not happen\n", type);
        return;
    }

    {
        u8 *ev  = ffs->ev.types, *out = ev;
        unsigned n = ffs->ev.count;
        for (; n; --n, ++ev)
            if ((*ev == rem_type1 || *ev == rem_type2) == neg)
                *out++ = *ev;
            else
                pr_vdebug("purging event %d\n", *ev);
        ffs->ev.count = out - ffs->ev.types;
    }

    pr_vdebug("adding event %d\n", type);
    ffs->ev.types[ffs->ev.count++] = type;
    wake_up_locked(&ffs->ev.waitq);
    if (ffs->ffs_eventfd)
        eventfd_signal(ffs->ffs_eventfd, 1);
}

static void ffs_event_add(struct ffs_data *ffs,
              enum usb_functionfs_event_type type)
{
    unsigned long flags;
    spin_lock_irqsave(&ffs->ev.waitq.lock, flags);
    __ffs_event_add(ffs, type);
    spin_unlock_irqrestore(&ffs->ev.waitq.lock, flags);
}

/* Bind/unbind USB function hooks *******************************************/

static int ffs_ep_addr2idx(struct ffs_data *ffs, u8 endpoint_address)
{
    int i;

    for (i = 1; i < ARRAY_SIZE(ffs->eps_addrmap); ++i)
        if (ffs->eps_addrmap[i] == endpoint_address)
            return i;
    return -ENOENT;
}

static int __ffs_func_bind_do_descs(enum ffs_entity_type type, u8 *valuep,
                struct usb_descriptor_header *desc,
                void *priv)
{
    struct usb_endpoint_descriptor *ds = (void *)desc;
    struct ffs_function *func = priv;
    struct ffs_ep *ffs_ep = NULL;
    unsigned ep_desc_id;
    int idx;
    static const char *speed_names[] = { "full", "high", "super" };

    if (type != FFS_DESCRIPTOR)
        return 0;

    /*
     * If ss_descriptors is not NULL, we are reading super speed
     * descriptors; if hs_descriptors is not NULL, we are reading high
     * speed descriptors; otherwise, we are reading full speed
     * descriptors.
     */
    if (func->function.ss_descriptors) {
        ep_desc_id = 2;
        func->function.ss_descriptors[(uintptr_t)valuep] = desc;
    } else if (func->function.hs_descriptors) {
        ep_desc_id = 1;
        func->function.hs_descriptors[(uintptr_t)valuep] = desc;
    } else {
        ep_desc_id = 0;
        func->function.fs_descriptors[(uintptr_t)valuep]    = desc;
    }

    if (!desc || desc->bDescriptorType != USB_DT_ENDPOINT)
        return 0;

    idx = ffs_ep_addr2idx(func->ffs, ds->bEndpointAddress) - 1;
    if (idx < 0)
        return idx;

    ffs_ep = func->eps + idx;

    if (unlikely(ffs_ep->descs[ep_desc_id])) {
        pr_err("two %sspeed descriptors for EP %d\n",
              speed_names[ep_desc_id],
              ds->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK);
        return -EINVAL;
    }
    ffs_ep->descs[ep_desc_id] = ds;

    ffs_dump_mem(": Original  ep desc", ds, ds->bLength);
    if (ffs_ep->ep) {
        ds->bEndpointAddress = ffs_ep->descs[0]->bEndpointAddress;
        if (!ds->wMaxPacketSize)
            ds->wMaxPacketSize = ffs_ep->descs[0]->wMaxPacketSize;
    } else {
        struct usb_request *req = NULL;
        struct usb_ep *ep = NULL;
        u8 bEndpointAddress;

        /*
         * We back up bEndpointAddress because autoconfig overwrites
         * it with physical endpoint address.
         */
        bEndpointAddress = ds->bEndpointAddress;
        pr_vdebug("autoconfig\n");
        ep = usb_ep_autoconfig(func->gadget, ds);
        if (unlikely(!ep))
            return -ENOTSUPP;
        ep->driver_data = func->eps + idx;

        req = usb_ep_alloc_request(ep, GFP_KERNEL);
        if (unlikely(!req))
            return -ENOMEM;

        ffs_ep->ep  = ep;
        ffs_ep->req = req;
            INIT_LIST_HEAD(&ffs_ep->req->list);
        func->eps_revmap[ds->bEndpointAddress &
                 USB_ENDPOINT_NUMBER_MASK] = idx + 1;
        /*
         * If we use virtual address mapping, we restore
         * original bEndpointAddress value.
         */
        if (func->ffs->user_flags & FUNCTIONFS_VIRTUAL_ADDR)
            ds->bEndpointAddress = bEndpointAddress;
    }
    ffs_dump_mem(": Rewritten ep desc", ds, ds->bLength);

    return 0;
}

static int __ffs_func_bind_do_nums(enum ffs_entity_type type, u8 *valuep,
                struct usb_descriptor_header *desc,
                void *priv)
{
    struct ffs_function *func = priv;
    unsigned idx;
    u8 newValue;

    switch (type) {
    default:
    case FFS_DESCRIPTOR:
        /* Handled in previous pass by __ffs_func_bind_do_descs() */
        return 0;

    case FFS_INTERFACE:
        idx = *valuep;
        if (func->interfaces_nums[idx] < 0) {
            int id = usb_interface_id(func->conf, &func->function);
            if (unlikely(id < 0))
                return id;
            func->interfaces_nums[idx] = id;
        }
        newValue = func->interfaces_nums[idx];
        break;

    case FFS_STRING:
        /* String' IDs are allocated when fsf_data is bound to cdev */
        newValue = func->ffs->stringtabs[0]->strings[*valuep - 1].id;
        break;

    case FFS_ENDPOINT:
        /*
         * USB_DT_ENDPOINT are handled in
         * __ffs_func_bind_do_descs().
         */
        if (desc->bDescriptorType == USB_DT_ENDPOINT)
            return 0;

        idx = (*valuep & USB_ENDPOINT_NUMBER_MASK) - 1;
        if (unlikely(!func->eps[idx].ep))
            return -EINVAL;

        {
            struct usb_endpoint_descriptor **descs;
            descs = func->eps[idx].descs;
            newValue = descs[descs[0] ? 0 : 1]->bEndpointAddress;
        }
        break;
    }

    pr_vdebug("%02x -> %02x\n", *valuep, newValue);
    *valuep = newValue;
    return 0;
}

static int __ffs_func_bind_do_os_desc(enum ffs_os_desc_type type,
                struct usb_os_desc_header *h, void *data,
                unsigned len, void *priv)
{
    struct ffs_function *func = priv;
    u8 length = 0;

    switch (type) {
    case FFS_OS_DESC_EXT_COMPAT: {
        struct usb_ext_compat_desc *desc = data;
        struct usb_os_desc_table *t;

        t = &func->function.os_desc_table[desc->bFirstInterfaceNumber];
        t->if_id = func->interfaces_nums[desc->bFirstInterfaceNumber];
        memcpy(t->os_desc->ext_compat_id, &desc->CompatibleID,
            ARRAY_SIZE(desc->CompatibleID) + ARRAY_SIZE(desc->SubCompatibleID));
        length = sizeof(*desc);
    }
        break;
    case FFS_OS_DESC_EXT_PROP: {
        struct usb_ext_prop_desc *desc = data;
        struct usb_os_desc_table *t;
        struct usb_os_desc_ext_prop *ext_prop;
        char *ext_prop_name;
        char *ext_prop_data;

        t = &func->function.os_desc_table[h->interface];
        t->if_id = func->interfaces_nums[h->interface];

        ext_prop = func->ffs->ms_os_descs_ext_prop_avail;
        func->ffs->ms_os_descs_ext_prop_avail += sizeof(*ext_prop);

        ext_prop->type = le32_to_cpu(desc->dwPropertyDataType);
        ext_prop->name_len = le16_to_cpu(desc->wPropertyNameLength);
        ext_prop->data_len = le32_to_cpu(*(__le32 *)
            usb_ext_prop_data_len_ptr(data, ext_prop->name_len));
        length = ext_prop->name_len + ext_prop->data_len + 14;

        ext_prop_name = func->ffs->ms_os_descs_ext_prop_name_avail;
        func->ffs->ms_os_descs_ext_prop_name_avail +=
            ext_prop->name_len;

        ext_prop_data = func->ffs->ms_os_descs_ext_prop_data_avail;
        func->ffs->ms_os_descs_ext_prop_data_avail +=
            ext_prop->data_len;
        memcpy(ext_prop_data, usb_ext_prop_data_ptr(data, ext_prop->name_len),
            ext_prop->data_len);
        /* unicode data reported to the host as "WCHAR"s */
        switch (ext_prop->type) {
        case USB_EXT_PROP_UNICODE:
        case USB_EXT_PROP_UNICODE_ENV:
        case USB_EXT_PROP_UNICODE_LINK:
        case USB_EXT_PROP_UNICODE_MULTI:
            ext_prop->data_len *= 2;
            break;
        }
        ext_prop->data = ext_prop_data;

        memcpy(ext_prop_name, usb_ext_prop_name_ptr(data),
            ext_prop->name_len);
		/* property name reported to the host as "WCHAR"s */
        ext_prop->name_len *= 2;
        ext_prop->name = ext_prop_name;

        t->os_desc->ext_prop_len +=
            ext_prop->name_len + ext_prop->data_len + 14;
        ++t->os_desc->ext_prop_count;
        list_add_tail(&ext_prop->entry, &t->os_desc->ext_prop);
    }
        break;
    default:
        pr_vdebug("unknown descriptor: %d\n", type);
    }

    return length;
}

static inline struct f_fs_opts *ffs_do_functionfs_bind(struct usb_function *f,
                struct usb_configuration *c)
{
    struct ffs_function *func = ffs_func_from_usb(f);
    struct f_fs_opts *ffs_opts =
        container_of(f->fi, struct f_fs_opts, func_inst);
    int ret;

    ENTER();

    /*
     * Legacy gadget triggers binding in functionfs_ready_callback,
     * which already uses locking; taking the same lock here would
     * cause a deadlock.
     *
     * Configfs-enabled gadgets however do need ffs_dev_lock.
     */
    if (!ffs_opts->no_configfs)
        ffs_dev_lock();
    ret = ffs_opts->dev->desc_ready ? 0 : -ENODEV;
    func->ffs = ffs_opts->dev->ffs_data;
    if (!ffs_opts->no_configfs)
        ffs_dev_unlock();
    if (ret)
        return ERR_PTR(ret);

    func->conf = c;
    func->gadget = c->cdev->gadget;

    /*
     * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
     * configurations are bound in sequence with list_for_each_entry,
     * in each configuration its functions are bound in sequence
     * with list_for_each_entry, so we assume no race condition
     * with regard to ffs_opts->bound access
     */
    if (!ffs_opts->refcnt) {
        ret = functionfs_bind(func->ffs, c->cdev);
        if (ret)
            return ERR_PTR(ret);
    }
    ffs_opts->refcnt++;
    func->function.strings = func->ffs->stringtabs;

    return ffs_opts;
}

static int _ffs_func_bind(struct usb_configuration *c, struct usb_function *f)
{
    struct ffs_function *func = ffs_func_from_usb(f);
    struct ffs_data *ffs = func->ffs;

    const int full = !!func->ffs->fs_descs_count;
    const int high = !!func->ffs->hs_descs_count;
    const int super = !!func->ffs->ss_descs_count;

    int fs_len, hs_len, ss_len, ret, i;
    struct ffs_ep *eps_ptr = NULL;
    struct usb_descriptor_header *des_head = NULL;
    struct usb_interface_descriptor *intf_ctl = NULL;
    struct usb_interface_descriptor *intf_data = NULL;
    /* Make it a single chunk, less management later on */
    vla_group(d);
    vla_item_with_sz(d, struct ffs_ep, eps, ffs->eps_count);
    vla_item_with_sz(d, struct usb_descriptor_header *, fs_descs,
        full ? ffs->fs_descs_count + 1 : 0);
    vla_item_with_sz(d, struct usb_descriptor_header *, hs_descs,
        high ? ffs->hs_descs_count + 1 : 0);
    vla_item_with_sz(d, struct usb_descriptor_header *, ss_descs,
        super ? ffs->ss_descs_count + 1 : 0);
    vla_item_with_sz(d, short, inums, ffs->interfaces_count);
    vla_item_with_sz(d, struct usb_os_desc_table, os_desc_table,
             c->cdev->use_os_string ? ffs->interfaces_count : 0);
    vla_item_with_sz(d, char[16], ext_compat,
             c->cdev->use_os_string ? ffs->interfaces_count : 0);
    vla_item_with_sz(d, struct usb_os_desc, os_desc,
             c->cdev->use_os_string ? ffs->interfaces_count : 0);
    vla_item_with_sz(d, struct usb_os_desc_ext_prop, ext_prop,
             ffs->ms_os_descs_ext_prop_count);
    vla_item_with_sz(d, char, ext_prop_name,
             ffs->ms_os_descs_ext_prop_name_len);
    vla_item_with_sz(d, char, ext_prop_data,
             ffs->ms_os_descs_ext_prop_data_len);
    vla_item_with_sz(d, char, raw_descs, ffs->raw_descs_length);
    char *vlabuf = NULL;

    ENTER();

    /* Has descriptors only for speeds gadget does not support */
    if (unlikely(!(full | high | super)))
        return -ENOTSUPP;

    /* Allocate a single chunk, less management later on */
    vlabuf = kzalloc(vla_group_size(d), GFP_KERNEL);
    if (unlikely(!vlabuf))
        return -ENOMEM;

    ffs->ms_os_descs_ext_prop_avail = vla_ptr(vlabuf, d, ext_prop);
    ffs->ms_os_descs_ext_prop_name_avail =
        vla_ptr(vlabuf, d, ext_prop_name);
    ffs->ms_os_descs_ext_prop_data_avail =
        vla_ptr(vlabuf, d, ext_prop_data);

    /* Copy descriptors  */
    memcpy(vla_ptr(vlabuf, d, raw_descs), ffs->raw_descs, ffs->raw_descs_length);

    memset(vla_ptr(vlabuf, d, inums), 0xff, d_inums__sz);

    eps_ptr = vla_ptr(vlabuf, d, eps);
    for (i = 0; i < ffs->eps_count; i++)
        eps_ptr[i].num = -1;

    /* Save pointers
     * d_eps == vlabuf, func->eps used to kfree vlabuf later
    */
    func->eps             = vla_ptr(vlabuf, d, eps);
    func->interfaces_nums = vla_ptr(vlabuf, d, inums);

    /*
     * Go through all the endpoint descriptors and allocate
     * endpoints first, so that later we can rewrite the endpoint
     * numbers without worrying that it may be described later on.
     */
    if (likely(full)) {
        func->function.fs_descriptors = vla_ptr(vlabuf, d, fs_descs);
        fs_len = ffs_do_descs(ffs->fs_descs_count,
                      vla_ptr(vlabuf, d, raw_descs),
                      d_raw_descs__sz,
                      __ffs_func_bind_do_descs, func);
        if (unlikely(fs_len < 0)) {
            ret = fs_len;
            goto error;
        }
    } else {
        fs_len = 0;
    }
    if (likely(high)) {
        func->function.hs_descriptors = vla_ptr(vlabuf, d, hs_descs);
        hs_len = ffs_do_descs(ffs->hs_descs_count,
                      vla_ptr(vlabuf, d, raw_descs) + fs_len,
                      d_raw_descs__sz - fs_len,
                      __ffs_func_bind_do_descs, func);
        if (unlikely(hs_len < 0)) {
            ret = hs_len;
            goto error;
        }
    } else {
        hs_len = 0;
    }
    if (likely(super)) {
        func->function.ss_descriptors = vla_ptr(vlabuf, d, ss_descs);
        ss_len = ffs_do_descs(ffs->ss_descs_count,
                vla_ptr(vlabuf, d, raw_descs) + fs_len + hs_len,
                d_raw_descs__sz - fs_len - hs_len,
                __ffs_func_bind_do_descs, func);
        if (unlikely(ss_len < 0)) {
            ret = ss_len;
            goto error;
        }
    } else {
        ss_len = 0;
    }
    /*
     * Now handle interface numbers allocation and interface and
     * endpoint numbers rewriting.  We can do that in one go
     * now.
     */
    ret = ffs_do_descs(ffs->fs_descs_count +
               (high ? ffs->hs_descs_count : 0) +
               (super ? ffs->ss_descs_count : 0),
               vla_ptr(vlabuf, d, raw_descs), d_raw_descs__sz,
               __ffs_func_bind_do_nums, func);
    if (unlikely(ret < 0))
        goto error;

    func->function.os_desc_table = vla_ptr(vlabuf, d, os_desc_table);
    if (c->cdev->use_os_string) {
        for (i = 0; i < ffs->interfaces_count; ++i) {
            struct usb_os_desc *desc;

            desc = func->function.os_desc_table[i].os_desc =
                vla_ptr(vlabuf, d, os_desc) +
                i * sizeof(struct usb_os_desc);
            desc->ext_compat_id =
                vla_ptr(vlabuf, d, ext_compat) + i * 16;
            INIT_LIST_HEAD(&desc->ext_prop);
        }
        ret = ffs_do_os_descs(ffs->ms_os_descs_count,
                      vla_ptr(vlabuf, d, raw_descs) +
                      fs_len + hs_len + ss_len,
                      d_raw_descs__sz - fs_len - hs_len -
                      ss_len,
                      __ffs_func_bind_do_os_desc, func);
        if (unlikely(ret < 0))
            goto error;
    }
    func->function.os_desc_n =
        c->cdev->use_os_string ? ffs->interfaces_count : 0;

    for (i = 0; i< func->ffs->fs_descs_count; i++) {
        des_head = func->function.fs_descriptors[i];
        if (des_head->bDescriptorType == USB_DT_INTERFACE) {
            struct usb_interface_descriptor *intf = (struct usb_interface_descriptor *)des_head;
            if (intf->bNumEndpoints > 0) {
                if (intf_ctl == NULL) {
                    intf_ctl = intf;
                } else {
                    intf_data = intf;
                    break;
                }
            }
        }
    }
    for (i = 0; i< func->ffs->fs_descs_count; i++) {
        des_head = func->function.fs_descriptors[i];
        if (des_head->bDescriptorType == USB_DT_INTERFACE_ASSOCIATION) {
            struct usb_interface_assoc_descriptor *a_dec = (struct usb_interface_assoc_descriptor *)des_head;
            a_dec->bFirstInterface = intf_ctl->bInterfaceNumber;
        } else if (des_head->bDescriptorType == USB_DT_CS_INTERFACE) {
            struct usb_cdc_header_desc *cs_des = (struct usb_cdc_header_desc *)des_head;
            if (cs_des->bDescriptorSubType == USB_CDC_CALL_MANAGEMENT_TYPE) {
                struct usb_cdc_call_mgmt_descriptor *mgmt_des = (struct usb_cdc_call_mgmt_descriptor *)des_head;
                mgmt_des->bDataInterface = intf_data->bInterfaceNumber;
            } else if (cs_des->bDescriptorSubType == USB_CDC_UNION_TYPE) {
                struct usb_cdc_union_desc *union_des = (struct usb_cdc_union_desc *)des_head;
                union_des->bMasterInterface0 = intf_ctl->bInterfaceNumber;
                union_des->bSlaveInterface0 = intf_data->bInterfaceNumber;
            } else if (cs_des->bDescriptorSubType == USB_CDC_ETHERNET_TYPE) {
                struct usb_cdc_ether_desc *ether_des = (struct usb_cdc_ether_desc *)des_head;
                ether_des->iMACAddress = intf_ctl->iInterface + 1;
            }
        }
    }
    for (i = 0; i< func->ffs->hs_descs_count; i++) {
        des_head = func->function.hs_descriptors[i];
        if (des_head->bDescriptorType == USB_DT_INTERFACE_ASSOCIATION) {
            struct usb_interface_assoc_descriptor *a_dec = (struct usb_interface_assoc_descriptor *)des_head;
            a_dec->bFirstInterface = intf_ctl->bInterfaceNumber;
        } else if (des_head->bDescriptorType == USB_DT_CS_INTERFACE) {
            struct usb_cdc_header_desc *cs_des = (struct usb_cdc_header_desc *)des_head;
            if (cs_des->bDescriptorSubType == USB_CDC_CALL_MANAGEMENT_TYPE) {
                struct usb_cdc_call_mgmt_descriptor *mgmt_des = (struct usb_cdc_call_mgmt_descriptor *)des_head;
                mgmt_des->bDataInterface = intf_data->bInterfaceNumber;
            } else if (cs_des->bDescriptorSubType == USB_CDC_UNION_TYPE) {
                struct usb_cdc_union_desc *union_des = (struct usb_cdc_union_desc *)des_head;
                union_des->bMasterInterface0 = intf_ctl->bInterfaceNumber;
                union_des->bSlaveInterface0 = intf_data->bInterfaceNumber;
            } else if (cs_des->bDescriptorSubType == USB_CDC_ETHERNET_TYPE) {
                struct usb_cdc_ether_desc *ether_des = (struct usb_cdc_ether_desc *)des_head;
                ether_des->iMACAddress = intf_ctl->iInterface + 1;
            }
        }
    }
    for (i = 0; i< func->ffs->ss_descs_count; i++) {
        des_head = func->function.ss_descriptors[i];
        if (des_head->bDescriptorType == USB_DT_INTERFACE_ASSOCIATION) {
            struct usb_interface_assoc_descriptor *a_dec = (struct usb_interface_assoc_descriptor *)des_head;
            a_dec->bFirstInterface = intf_ctl->bInterfaceNumber;
        } else if (des_head->bDescriptorType == USB_DT_CS_INTERFACE) {
            struct usb_cdc_header_desc *cs_des = (struct usb_cdc_header_desc *)des_head;
            if (cs_des->bDescriptorSubType == USB_CDC_CALL_MANAGEMENT_TYPE) {
                struct usb_cdc_call_mgmt_descriptor *mgmt_des = (struct usb_cdc_call_mgmt_descriptor *)des_head;
                mgmt_des->bDataInterface = intf_data->bInterfaceNumber;
            } else if (cs_des->bDescriptorSubType == USB_CDC_UNION_TYPE) {
                struct usb_cdc_union_desc *union_des = (struct usb_cdc_union_desc *)des_head;
                union_des->bMasterInterface0 = intf_ctl->bInterfaceNumber;
                union_des->bSlaveInterface0 = intf_data->bInterfaceNumber;
            } else if (cs_des->bDescriptorSubType == USB_CDC_ETHERNET_TYPE) {
                struct usb_cdc_ether_desc *ether_des = (struct usb_cdc_ether_desc *)des_head;
                ether_des->iMACAddress = intf_ctl->iInterface + 1;
            }
        }
    }
    /* And we're done */
    ffs->eps = func->eps;
    ffs_event_add(ffs, FUNCTIONFS_BIND);
    return 0;

error:
    /* XXX Do we need to release all claimed endpoints here? */
    return ret;
}

static int ffs_func_bind(struct usb_configuration *c, struct usb_function *f)
{
    struct f_fs_opts *ffs_opts = ffs_do_functionfs_bind(f, c);
    struct ffs_function *func = ffs_func_from_usb(f);
    int ret;

    if (IS_ERR(ffs_opts))
        return PTR_ERR(ffs_opts);

    ret = _ffs_func_bind(c, f);
    if (ret && !--ffs_opts->refcnt)
        functionfs_unbind(func->ffs);

    return ret;
}

/* Other USB function hooks *************************************************/
static void ffs_reset_work(struct work_struct *work)
{
    struct ffs_data *ffs = container_of(work,
        struct ffs_data, reset_work);
    ffs_data_reset(ffs);
}

static int ffs_func_set_alt(struct usb_function *f,
                unsigned interface, unsigned alt)
{
    struct ffs_function *func = ffs_func_from_usb(f);
    struct ffs_data *ffs = func->ffs;
    int ret = 0, intf;

    if (alt != (unsigned)-1) {
        intf = ffs_func_revmap_intf(func, interface);
        if (unlikely(intf < 0))
            return intf;
    }

    if (ffs->func)
        ffs_func_eps_disable(ffs->func);

    if (ffs->state == FFS_DEACTIVATED) {
        ffs->state = FFS_CLOSING;
        INIT_WORK(&ffs->reset_work, ffs_reset_work);
        schedule_work(&ffs->reset_work);
        return -ENODEV;
    }

    if (ffs->state != FFS_ACTIVE)
        return -ENODEV;

    if (alt == (unsigned)-1) {
        ffs->func = NULL;
        ffs_event_add(ffs, FUNCTIONFS_DISABLE);
        return 0;
    }

    ffs->func = func;
    ret = ffs_func_eps_enable(func);
    if (likely(ret >= 0))
        ffs_event_add(ffs, FUNCTIONFS_ENABLE);
    return ret;
}

static void ffs_func_disable(struct usb_function *f)
{
    ffs_func_set_alt(f, 0, (unsigned)-1);
}

static int ffs_func_setup(struct usb_function *f, const struct usb_ctrlrequest *creq)
{
    struct ffs_function *func = ffs_func_from_usb(f);
    struct ffs_data *ffs = func->ffs;
    unsigned long flags;
    int ret;

    ENTER();

    pr_vdebug("creq->bRequestType = %02x\n", creq->bRequestType);
    pr_vdebug("creq->bRequest     = %02x\n", creq->bRequest);
    pr_vdebug("creq->wValue       = %04x\n", le16_to_cpu(creq->wValue));
    pr_vdebug("creq->wIndex       = %04x\n", le16_to_cpu(creq->wIndex));
    pr_vdebug("creq->wLength      = %04x\n", le16_to_cpu(creq->wLength));

    /*
     * Most requests directed to interface go through here
     * (notable exceptions are set/get interface) so we need to
     * handle them.  All other either handled by composite or
     * passed to usb_configuration->setup() (if one is set).  No
     * matter, we will handle requests directed to endpoint here
     * as well (as it's straightforward).  Other request recipient
     * types are only handled when the user flag FUNCTIONFS_ALL_CTRL_RECIP
     * is being used.
     */
    if (ffs->state != FFS_ACTIVE)
        return -ENODEV;

    switch (creq->bRequestType & USB_RECIP_MASK) {
    case USB_RECIP_INTERFACE:
        ret = ffs_func_revmap_intf(func, le16_to_cpu(creq->wIndex));
        if (unlikely(ret < 0))
            return ret;
        break;

    case USB_RECIP_ENDPOINT:
        ret = ffs_func_revmap_ep(func, le16_to_cpu(creq->wIndex));
        if (unlikely(ret < 0))
            return ret;
        if (func->ffs->user_flags & FUNCTIONFS_VIRTUAL_ADDR)
            ret = func->ffs->eps_addrmap[ret];
        break;

    default:
        if (func->ffs->user_flags & FUNCTIONFS_ALL_CTRL_RECIP)
            ret = le16_to_cpu(creq->wIndex);
        else
            return -EOPNOTSUPP;
    }

    spin_lock_irqsave(&ffs->ev.waitq.lock, flags);
    ffs->ev.setup = *creq;
    ffs->ev.setup.wIndex = cpu_to_le16(ret);
    __ffs_event_add(ffs, FUNCTIONFS_SETUP);
    spin_unlock_irqrestore(&ffs->ev.waitq.lock, flags);

    return creq->wLength == 0 ? USB_GADGET_DELAYED_STATUS : 0;
}

static bool ffs_func_req_match(struct usb_function *f,
                const struct usb_ctrlrequest *creq,
                bool config0)
{
    struct ffs_function *func = ffs_func_from_usb(f);

    if (config0 && !(func->ffs->user_flags & FUNCTIONFS_CONFIG0_SETUP))
        return false;

    switch (creq->bRequestType & USB_RECIP_MASK) {
    case USB_RECIP_INTERFACE:
        return (ffs_func_revmap_intf(func,
                         le16_to_cpu(creq->wIndex)) >= 0);
    case USB_RECIP_ENDPOINT:
        return (ffs_func_revmap_ep(func,
                       le16_to_cpu(creq->wIndex)) >= 0);
    default:
        return (bool) (func->ffs->user_flags &
                   FUNCTIONFS_ALL_CTRL_RECIP);
    }
}

static void ffs_func_suspend(struct usb_function *f)
{
    ENTER();
    ffs_event_add(ffs_func_from_usb(f)->ffs, FUNCTIONFS_SUSPEND);
}

static void ffs_func_resume(struct usb_function *f)
{
    ENTER();
    ffs_event_add(ffs_func_from_usb(f)->ffs, FUNCTIONFS_RESUME);
}

/* Endpoint and interface numbers reverse mapping ***************************/
static int ffs_func_revmap_ep(struct ffs_function *func, u8 num)
{
    num = func->eps_revmap[num & USB_ENDPOINT_NUMBER_MASK];
    return num ? num : -EDOM;
}

static int ffs_func_revmap_intf(struct ffs_function *func, u8 intf)
{
    short *nums = func->interfaces_nums;
    unsigned count = func->ffs->interfaces_count;

    for (; count; --count, ++nums) {
        if (*nums >= 0 && *nums == intf)
            return nums - func->interfaces_nums;
    }

    return -EDOM;
}

/* Devices management *******************************************************/
static LIST_HEAD(ffs_devices);

static struct ffs_dev *_ffs_do_find_dev(const char *name)
{
    struct ffs_dev *dev = NULL;

    if (!name)
        return NULL;

    list_for_each_entry(dev, &ffs_devices, entry) {
        if (!dev->name)
            return NULL;
        if (strcmp(dev->name, name) == 0)
            return dev;
    }

    return NULL;
}

/*
 * ffs_lock must be taken by the caller of this function
 */
static struct ffs_dev *_ffs_get_single_dev(void)
{
    struct ffs_dev *dev = NULL;

    if (list_is_singular(&ffs_devices)) {
        dev = list_first_entry(&ffs_devices, struct ffs_dev, entry);
        if (dev->single)
            return dev;
    }

    return NULL;
}

/*
 * ffs_lock must be taken by the caller of this function
 */
static struct ffs_dev *_ffs_find_dev(const char *name)
{
    struct ffs_dev *dev;

    dev = _ffs_get_single_dev();
    if (dev)
        return dev;

    return _ffs_do_find_dev(name);
}

/* Configfs support *********************************************************/
static inline struct f_fs_opts *to_ffs_opts(struct config_item *item)
{
    return container_of(to_config_group(item), struct f_fs_opts,
                func_inst.group);
}

static void ffs_attr_release(struct config_item *item)
{
    struct f_fs_opts *opts = to_ffs_opts(item);

    usb_put_function_instance(&opts->func_inst);
}

static struct configfs_item_operations ffs_item_ops = {
    .release    = ffs_attr_release,
};

static const struct config_item_type ffs_func_type = {
    .ct_item_ops    = &ffs_item_ops,
    .ct_owner    = THIS_MODULE,
};

/* Function registration interface ******************************************/
static void ffs_free_inst(struct usb_function_instance *f)
{
    struct f_fs_opts *opts;

    opts = to_f_fs_opts(f);
    ffs_dev_lock();
    _ffs_free_dev(opts->dev);
    ffs_dev_unlock();
    kfree(opts);
}

static int ffs_set_inst_name(struct usb_function_instance *fi, const char *name)
{
    char name_dev[MAX_NAMELEN] = {0};
    if (snprintf(name_dev, MAX_NAMELEN - 1, "%s.%s", FUNCTION_GENERIC, name) < 0) {
        return -EFAULT;
    }
    if (strlen(name_dev) >= sizeof_field(struct ffs_dev, name))
        return -ENAMETOOLONG;
    return ffs_name_dev_adapter(to_f_fs_opts(fi)->dev, name_dev);
}

static struct usb_function_instance *ffs_alloc_inst(void)
{
    struct f_fs_opts *opts = NULL;
    struct ffs_dev *dev = NULL;

    opts = kzalloc(sizeof(*opts), GFP_KERNEL);
    if (!opts)
        return ERR_PTR(-ENOMEM);

    opts->func_inst.set_inst_name = ffs_set_inst_name;
    opts->func_inst.free_func_inst = ffs_free_inst;
    ffs_dev_lock();
    dev = _ffs_alloc_dev();
    ffs_dev_unlock();
    if (IS_ERR(dev)) {
        kfree(opts);
        return ERR_CAST(dev);
    }
    opts->dev = dev;
    dev->opts = opts;

    config_group_init_type_name(&opts->func_inst.group, "",
                    &ffs_func_type);
    return &opts->func_inst;
}

static void ffs_free(struct usb_function *f)
{
    kfree(ffs_func_from_usb(f));
}

static void ffs_func_unbind(struct usb_configuration *c,
                struct usb_function *f)
{
    struct ffs_function *func = ffs_func_from_usb(f);
    struct ffs_data *ffs = func->ffs;
    struct f_fs_opts *opts =
        container_of(f->fi, struct f_fs_opts, func_inst);
    struct ffs_ep *ep = func->eps;
    unsigned count = ffs->eps_count;
    unsigned long flags;

    ENTER();
    if (ffs->func == func) {
        ffs_func_eps_disable(func);
        ffs->func = NULL;
    }

    if (!--opts->refcnt)
        functionfs_unbind(ffs);

    /* cleanup after autoconfig */
    spin_lock_irqsave(&func->ffs->eps_lock, flags);
    while (count--) {
        if (ep->ep && ep->req)
            usb_ep_free_request(ep->ep, ep->req);
        ep->req = NULL;
        ++ep;
    }
    spin_unlock_irqrestore(&func->ffs->eps_lock, flags);
    kfree(func->eps);
    func->eps = NULL;
    /*
     * eps, descriptors and interfaces_nums are allocated in the
     * same chunk so only one free is required.
     */
    func->function.fs_descriptors = NULL;
    func->function.hs_descriptors = NULL;
    func->function.ss_descriptors = NULL;
    func->interfaces_nums = NULL;

    ffs_event_add(ffs, FUNCTIONFS_UNBIND);
}

static int ffs_func_get_alt(struct usb_function *f, unsigned intf)
{
    if (intf == 0)
        return 0;
    return 1;
}

static struct usb_function *ffs_alloc(struct usb_function_instance *fi)
{
    struct ffs_function *func = NULL;

    ENTER();

    func = kzalloc(sizeof(*func), GFP_KERNEL);
    if (unlikely(!func))
        return ERR_PTR(-ENOMEM);

    func->function.name    = "FunctionFS Adapter";

    func->function.bind    = ffs_func_bind;
    func->function.unbind  = ffs_func_unbind;
    func->function.set_alt = ffs_func_set_alt;
    func->function.get_alt = ffs_func_get_alt;
    func->function.disable = ffs_func_disable;
    func->function.setup   = ffs_func_setup;
    func->function.req_match = ffs_func_req_match;
    func->function.suspend = ffs_func_suspend;
    func->function.resume  = ffs_func_resume;
    func->function.free_func = ffs_free;

    return &func->function;
}

/*
 * ffs_lock must be taken by the caller of this function
 */
static struct ffs_dev *_ffs_alloc_dev(void)
{
    struct ffs_dev *dev = NULL;
    int ret;

    if (_ffs_get_single_dev())
            return ERR_PTR(-EBUSY);

    dev = kzalloc(sizeof(*dev), GFP_KERNEL);
    if (!dev)
        return ERR_PTR(-ENOMEM);

    if (list_empty(&ffs_devices)) {
        ret = functionfs_init();
        if (ret) {
            kfree(dev);
            return ERR_PTR(ret);
        }
    }

    list_add(&dev->entry, &ffs_devices);

    return dev;
}

int ffs_name_dev_adapter(struct ffs_dev *dev, const char *name)
{
    struct ffs_dev *existing = NULL;
    int ret = 0;

    ffs_dev_lock();

    existing = _ffs_do_find_dev(name);
    if (!existing)
        strlcpy(dev->name, name, ARRAY_SIZE(dev->name));
    else if (existing != dev)
        ret = -EBUSY;

    ffs_dev_unlock();

    return ret;
}
EXPORT_SYMBOL_GPL(ffs_name_dev_adapter);

int ffs_single_dev_adapter(struct ffs_dev *dev)
{
    int ret;

    ret = 0;
    ffs_dev_lock();

    if (!list_is_singular(&ffs_devices))
        ret = -EBUSY;
    else
        dev->single = true;

    ffs_dev_unlock();
    return ret;
}
EXPORT_SYMBOL_GPL(ffs_single_dev_adapter);
/*
 * ffs_lock must be taken by the caller of this function
 */
static void _ffs_free_dev(struct ffs_dev *dev)
{
    list_del(&dev->entry);

    /* Clear the private_data pointer to stop incorrect dev access */
    if (dev->ffs_data)
        dev->ffs_data->private_data = NULL;

    kfree(dev);
    if (list_empty(&ffs_devices))
        functionfs_cleanup();
}

static void *ffs_acquire_dev(const char *dev_name)
{
    struct ffs_dev *ffs_dev = NULL;

    ENTER();
    ffs_dev_lock();

    ffs_dev = _ffs_find_dev(dev_name);
    if (!ffs_dev)
        ffs_dev = ERR_PTR(-ENOENT);
    else if (ffs_dev->mounted)
        ffs_dev = ERR_PTR(-EBUSY);
    else if (ffs_dev->ffs_acquire_dev_callback &&
        ffs_dev->ffs_acquire_dev_callback(ffs_dev))
        ffs_dev = ERR_PTR(-ENOENT);
    else
        ffs_dev->mounted = true;

    ffs_dev_unlock();
    return ffs_dev;
}

static void ffs_release_dev(struct ffs_data *ffs_data)
{
    struct ffs_dev *ffs_dev = NULL;

    ENTER();
    ffs_dev_lock();

    ffs_dev = ffs_data->private_data;
    if (ffs_dev) {
        ffs_dev->mounted = false;

        if (ffs_dev->ffs_release_dev_callback)
            ffs_dev->ffs_release_dev_callback(ffs_dev);
    }

    ffs_dev_unlock();
}

static int ffs_ready(struct ffs_data *ffs)
{
    struct ffs_dev *ffs_obj = NULL;
    int ret = 0;

    ENTER();
    ffs_dev_lock();

    ffs_obj = ffs->private_data;
    if (!ffs_obj) {
        ret = -EINVAL;
        goto done;
    }
    if (WARN_ON(ffs_obj->desc_ready)) {
        ret = -EBUSY;
        goto done;
    }

    ffs_obj->desc_ready = true;
    ffs_obj->ffs_data = ffs;

    if (ffs_obj->ffs_ready_callback) {
        ret = ffs_obj->ffs_ready_callback(ffs);
        if (ret)
            goto done;
    }

    set_bit(FFS_FL_CALL_CLOSED_CALLBACK, &ffs->flags);
done:
    ffs_dev_unlock();
    return ret;
}

static void ffs_closed(struct ffs_data *ffs)
{
    struct ffs_dev *ffs_obj = NULL;
    struct f_fs_opts *opts = NULL;
    struct config_item *ci = NULL;

    ENTER();
    ffs_dev_lock();

    ffs_obj = ffs->private_data;
    if (!ffs_obj)
        goto done;

    ffs_obj->desc_ready = false;
    ffs_obj->ffs_data = NULL;

    if (test_and_clear_bit(FFS_FL_CALL_CLOSED_CALLBACK, &ffs->flags) &&
        ffs_obj->ffs_closed_callback)
        ffs_obj->ffs_closed_callback(ffs);

    if (ffs_obj->opts)
        opts = ffs_obj->opts;
    else
        goto done;

    if (opts->no_configfs || !opts->func_inst.group.cg_item.ci_parent
        || !kref_read(&opts->func_inst.group.cg_item.ci_kref))
        goto done;

    ci = opts->func_inst.group.cg_item.ci_parent->ci_parent;
    ffs_dev_unlock();

    if (test_bit(FFS_FL_BOUND, &ffs->flags))
        unregister_gadget_item(ci);
    return;
done:
    ffs_dev_unlock();
}

/* Misc helper functions ****************************************************/
static int ffs_mutex_lock(struct mutex *mutex, unsigned nonblock)
{
    return nonblock
        ? likely(mutex_trylock(mutex)) ? 0 : -EAGAIN
        : mutex_lock_interruptible(mutex);
}

static char *ffs_prepare_buffer(const char __user *buf, size_t len)
{
    char *data = NULL;

    if (unlikely(!len))
        return NULL;

    data = kmalloc(len, GFP_KERNEL);
    if (unlikely(!data))
        return ERR_PTR(-ENOMEM);

    if (unlikely(copy_from_user(data, buf, len))) {
        kfree(data);
        return ERR_PTR(-EFAULT);
    }

    pr_vdebug("Buffer from user space:\n");
    ffs_dump_mem("", data, len);

    return data;
}

DECLARE_USB_FUNCTION_INIT(f_generic, ffs_alloc_inst, ffs_alloc);
MODULE_LICENSE("GPL");