/*
 * printer.c -- Printer gadget driver
 *
 * Copyright (C) 2003-2005 David Brownell
 * Copyright (C) 2006 Craig W. Nadler
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/timer.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/utsname.h>
#include <linux/device.h>
#include <linux/moduleparam.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/types.h>
#include <linux/ctype.h>
#include <linux/cdev.h>

#include <asm/byteorder.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <asm/system.h>
#include <linux/uaccess.h>
#include <asm/unaligned.h>

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

#include "gadget_chips.h"


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

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

#define DRIVER_DESC             "Printer Gadget"
#define DRIVER_VERSION          "2007 OCT 06"

static DEFINE_MUTEX(printer_mutex);
static const char shortname [] = "printer";
static const char driver_desc [] = DRIVER_DESC;

static dev_t g_printer_devno;

static struct class *usb_gadget_class;

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

struct printer_dev {
        spinlock_t              lock;           /* lock this structure */
        /* lock buffer lists during read/write calls */
        struct mutex            lock_printer_io;
        struct usb_gadget       *gadget;
        struct usb_request      *req;           /* for control responses */
        u8                      config;
        s8                      interface;
        struct usb_ep           *in_ep, *out_ep;

        struct list_head        rx_reqs;        /* List of free RX structs */
        struct list_head        rx_reqs_active; /* List of Active RX xfers */
        struct list_head        rx_buffers;     /* List of completed xfers */
        /* wait until there is data to be read. */
        wait_queue_head_t       rx_wait;
        struct list_head        tx_reqs;        /* List of free TX structs */
        struct list_head        tx_reqs_active; /* List of Active TX xfers */
        /* Wait until there are write buffers available to use. */
        wait_queue_head_t       tx_wait;
        /* Wait until all write buffers have been sent. */
        wait_queue_head_t       tx_flush_wait;
        struct usb_request      *current_rx_req;
        size_t                  current_rx_bytes;
        u8                      *current_rx_buf;
        u8                      printer_status;
        u8                      reset_printer;
        struct cdev             printer_cdev;
        struct device           *pdev;
        u8                      printer_cdev_open;
        wait_queue_head_t       wait;
};

static struct printer_dev usb_printer_gadget;

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

/* DO NOT REUSE THESE IDs with a protocol-incompatible driver!!  Ever!!
 * Instead:  allocate your own, using normal USB-IF procedures.
 */

/* Thanks to NetChip Technologies for donating this product ID.
 */
#define PRINTER_VENDOR_NUM      0x0525          /* NetChip */
#define PRINTER_PRODUCT_NUM     0xa4a8          /* Linux-USB Printer Gadget */

/* Some systems will want different product identifiers published in the
 * device descriptor, either numbers or strings or both.  These string
 * parameters are in UTF-8 (superset of ASCII's 7 bit characters).
 */

static ushort idVendor;
module_param(idVendor, ushort, S_IRUGO);
MODULE_PARM_DESC(idVendor, "USB Vendor ID");

static ushort idProduct;
module_param(idProduct, ushort, S_IRUGO);
MODULE_PARM_DESC(idProduct, "USB Product ID");

static ushort bcdDevice;
module_param(bcdDevice, ushort, S_IRUGO);
MODULE_PARM_DESC(bcdDevice, "USB Device version (BCD)");

static char *iManufacturer;
module_param(iManufacturer, charp, S_IRUGO);
MODULE_PARM_DESC(iManufacturer, "USB Manufacturer string");

static char *iProduct;
module_param(iProduct, charp, S_IRUGO);
MODULE_PARM_DESC(iProduct, "USB Product string");

static char *iSerialNum;
module_param(iSerialNum, charp, S_IRUGO);
MODULE_PARM_DESC(iSerialNum, "1");

static char *iPNPstring;
module_param(iPNPstring, charp, S_IRUGO);
MODULE_PARM_DESC(iPNPstring, "MFG:linux;MDL:g_printer;CLS:PRINTER;SN:1;");

/* Number of requests to allocate per endpoint, not used for ep0. */
static unsigned qlen = 10;
module_param(qlen, uint, S_IRUGO|S_IWUSR);

#define QLEN    qlen

#ifdef CONFIG_USB_GADGET_DUALSPEED
#define DEVSPEED        USB_SPEED_HIGH
#else   /* full speed (low speed doesn't do bulk) */
#define DEVSPEED        USB_SPEED_FULL
#endif

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

#define xprintk(d, level, fmt, args...) \
        printk(level "%s: " fmt, DRIVER_DESC, ## args)

#ifdef DEBUG
#define DBG(dev, fmt, args...) \
        xprintk(dev, KERN_DEBUG, fmt, ## args)
#else
#define DBG(dev, fmt, args...) \
        do { } while (0)
#endif /* DEBUG */

#ifdef VERBOSE
#define VDBG(dev, fmt, args...) \
        xprintk(dev, KERN_DEBUG, fmt, ## args)
#else
#define VDBG(dev, fmt, args...) \
        do { } while (0)
#endif /* VERBOSE */

#define ERROR(dev, fmt, args...) \
        xprintk(dev, KERN_ERR, fmt, ## args)
#define WARNING(dev, fmt, args...) \
        xprintk(dev, KERN_WARNING, fmt, ## args)
#define INFO(dev, fmt, args...) \
        xprintk(dev, KERN_INFO, fmt, ## args)

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

/* USB DRIVER HOOKUP (to the hardware driver, below us), mostly
 * ep0 implementation:  descriptors, config management, setup().
 * also optional class-specific notification interrupt transfer.
 */

/*
 * DESCRIPTORS ... most are static, but strings and (full) configuration
 * descriptors are built on demand.
 */

#define STRING_MANUFACTURER             1
#define STRING_PRODUCT                  2
#define STRING_SERIALNUM                3

/* holds our biggest descriptor */
#define USB_DESC_BUFSIZE                256
#define USB_BUFSIZE                     8192

/* This device advertises one configuration. */
#define DEV_CONFIG_VALUE                1
#define PRINTER_INTERFACE               0

static struct usb_device_descriptor device_desc = {
        .bLength =              sizeof device_desc,
        .bDescriptorType =      USB_DT_DEVICE,
        .bcdUSB =               cpu_to_le16(0x0200),
        .bDeviceClass =         USB_CLASS_PER_INTERFACE,
        .bDeviceSubClass =      0,
        .bDeviceProtocol =      0,
        .idVendor =             cpu_to_le16(PRINTER_VENDOR_NUM),
        .idProduct =            cpu_to_le16(PRINTER_PRODUCT_NUM),
        .iManufacturer =        STRING_MANUFACTURER,
        .iProduct =             STRING_PRODUCT,
        .iSerialNumber =        STRING_SERIALNUM,
        .bNumConfigurations =   1
};

static struct usb_otg_descriptor otg_desc = {
        .bLength =              sizeof otg_desc,
        .bDescriptorType =      USB_DT_OTG,
        .bmAttributes =         USB_OTG_SRP
};

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

        /* compute wTotalLength on the fly */
        .bNumInterfaces =       1,
        .bConfigurationValue =  DEV_CONFIG_VALUE,
        .iConfiguration =       0,
        .bmAttributes =         USB_CONFIG_ATT_ONE | USB_CONFIG_ATT_SELFPOWER,
        .bMaxPower =            CONFIG_USB_GADGET_VBUS_DRAW / 2,
};

static struct usb_interface_descriptor intf_desc = {
        .bLength =              sizeof intf_desc,
        .bDescriptorType =      USB_DT_INTERFACE,
        .bInterfaceNumber =     PRINTER_INTERFACE,
        .bNumEndpoints =        2,
        .bInterfaceClass =      USB_CLASS_PRINTER,
        .bInterfaceSubClass =   1,      /* Printer Sub-Class */
        .bInterfaceProtocol =   2,      /* Bi-Directional */
        .iInterface =           0
};

static struct usb_endpoint_descriptor fs_ep_in_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,
        .bEndpointAddress =     USB_DIR_IN,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK
};

static struct usb_endpoint_descriptor fs_ep_out_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,
        .bEndpointAddress =     USB_DIR_OUT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK
};

static const struct usb_descriptor_header *fs_printer_function [11] = {
        (struct usb_descriptor_header *) &otg_desc,
        (struct usb_descriptor_header *) &intf_desc,
        (struct usb_descriptor_header *) &fs_ep_in_desc,
        (struct usb_descriptor_header *) &fs_ep_out_desc,
        NULL
};

#ifdef  CONFIG_USB_GADGET_DUALSPEED

/*
 * usb 2.0 devices need to expose both high speed and full speed
 * descriptors, unless they only run at full speed.
 */

static struct usb_endpoint_descriptor hs_ep_in_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(512)
};

static struct usb_endpoint_descriptor hs_ep_out_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(512)
};

static struct usb_qualifier_descriptor dev_qualifier = {
        .bLength =              sizeof dev_qualifier,
        .bDescriptorType =      USB_DT_DEVICE_QUALIFIER,
        .bcdUSB =               cpu_to_le16(0x0200),
        .bDeviceClass =         USB_CLASS_PRINTER,
        .bNumConfigurations =   1
};

static const struct usb_descriptor_header *hs_printer_function [11] = {
        (struct usb_descriptor_header *) &otg_desc,
        (struct usb_descriptor_header *) &intf_desc,
        (struct usb_descriptor_header *) &hs_ep_in_desc,
        (struct usb_descriptor_header *) &hs_ep_out_desc,
        NULL
};

/* maxpacket and other transfer characteristics vary by speed. */
#define ep_desc(g, hs, fs) (((g)->speed == USB_SPEED_HIGH)?(hs):(fs))

#else

/* if there's no high speed support, maxpacket doesn't change. */
#define ep_desc(g, hs, fs) (((void)(g)), (fs))

#endif  /* !CONFIG_USB_GADGET_DUALSPEED */

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

/* descriptors that are built on-demand */

static char                             manufacturer [50];
static char                             product_desc [40] = DRIVER_DESC;
static char                             serial_num [40] = "1";
static char                             pnp_string [1024] =
        "XXMFG:linux;MDL:g_printer;CLS:PRINTER;SN:1;";

/* static strings, in UTF-8 */
static struct usb_string                strings [] = {
        { STRING_MANUFACTURER,  manufacturer, },
        { STRING_PRODUCT,       product_desc, },
        { STRING_SERIALNUM,     serial_num, },
        {  }            /* end of list */
};

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

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

static struct usb_request *
printer_req_alloc(struct usb_ep *ep, unsigned len, gfp_t gfp_flags)
{
        struct usb_request      *req;

        req = usb_ep_alloc_request(ep, gfp_flags);

        if (req != NULL) {
                req->length = len;
                req->buf = kmalloc(len, gfp_flags);
                if (req->buf == NULL) {
                        usb_ep_free_request(ep, req);
                        return NULL;
                }
        }

        return req;
}

static void
printer_req_free(struct usb_ep *ep, struct usb_request *req)
{
        if (ep != NULL && req != NULL) {
                kfree(req->buf);
                usb_ep_free_request(ep, req);
        }
}

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

static void rx_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct printer_dev      *dev = ep->driver_data;
        int                     status = req->status;
        unsigned long           flags;

        spin_lock_irqsave(&dev->lock, flags);

        list_del_init(&req->list);      /* Remode from Active List */

        switch (status) {

        /* normal completion */
        case 0:
                if (req->actual > 0) {
                        list_add_tail(&req->list, &dev->rx_buffers);
                        DBG(dev, "G_Printer : rx length %d\n", req->actual);
                } else {
                        list_add(&req->list, &dev->rx_reqs);
                }
                break;

        /* software-driven interface shutdown */
        case -ECONNRESET:               /* unlink */
        case -ESHUTDOWN:                /* disconnect etc */
                VDBG(dev, "rx shutdown, code %d\n", status);
                list_add(&req->list, &dev->rx_reqs);
                break;

        /* for hardware automagic (such as pxa) */
        case -ECONNABORTED:             /* endpoint reset */
                DBG(dev, "rx %s reset\n", ep->name);
                list_add(&req->list, &dev->rx_reqs);
                break;

        /* data overrun */
        case -EOVERFLOW:
                /* FALLTHROUGH */

        default:
                DBG(dev, "rx status %d\n", status);
                list_add(&req->list, &dev->rx_reqs);
                break;
        }

        wake_up_interruptible(&dev->rx_wait);
        spin_unlock_irqrestore(&dev->lock, flags);
}

static void tx_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct printer_dev      *dev = ep->driver_data;

        switch (req->status) {
        default:
                VDBG(dev, "tx err %d\n", req->status);
                /* FALLTHROUGH */
        case -ECONNRESET:               /* unlink */
        case -ESHUTDOWN:                /* disconnect etc */
                break;
        case 0:
                break;
        }

        spin_lock(&dev->lock);
        /* Take the request struct off the active list and put it on the
         * free list.
         */
        list_del_init(&req->list);
        list_add(&req->list, &dev->tx_reqs);
        wake_up_interruptible(&dev->tx_wait);
        if (likely(list_empty(&dev->tx_reqs_active)))
                wake_up_interruptible(&dev->tx_flush_wait);

        spin_unlock(&dev->lock);
}

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

static int
printer_open(struct inode *inode, struct file *fd)
{
        struct printer_dev      *dev;
        unsigned long           flags;
        int                     ret = -EBUSY;

        mutex_lock(&printer_mutex);
        dev = container_of(inode->i_cdev, struct printer_dev, printer_cdev);

        spin_lock_irqsave(&dev->lock, flags);

        if (!dev->printer_cdev_open) {
                dev->printer_cdev_open = 1;
                fd->private_data = dev;
                ret = 0;
                /* Change the printer status to show that it's on-line. */
                dev->printer_status |= PRINTER_SELECTED;
        }

        spin_unlock_irqrestore(&dev->lock, flags);

        DBG(dev, "printer_open returned %x\n", ret);
        mutex_unlock(&printer_mutex);
        return ret;
}

static int
printer_close(struct inode *inode, struct file *fd)
{
        struct printer_dev      *dev = fd->private_data;
        unsigned long           flags;

        spin_lock_irqsave(&dev->lock, flags);
        dev->printer_cdev_open = 0;
        fd->private_data = NULL;
        /* Change printer status to show that the printer is off-line. */
        dev->printer_status &= ~PRINTER_SELECTED;
        spin_unlock_irqrestore(&dev->lock, flags);

        DBG(dev, "printer_close\n");

        return 0;
}

/* This function must be called with interrupts turned off. */
static void
setup_rx_reqs(struct printer_dev *dev)
{
        struct usb_request              *req;

        while (likely(!list_empty(&dev->rx_reqs))) {
                int error;

                req = container_of(dev->rx_reqs.next,
                                struct usb_request, list);
                list_del_init(&req->list);

                /* The USB Host sends us whatever amount of data it wants to
                 * so we always set the length field to the full USB_BUFSIZE.
                 * If the amount of data is more than the read() caller asked
                 * for it will be stored in the request buffer until it is
                 * asked for by read().
                 */
                req->length = USB_BUFSIZE;
                req->complete = rx_complete;

                error = usb_ep_queue(dev->out_ep, req, GFP_ATOMIC);
                if (error) {
                        DBG(dev, "rx submit --> %d\n", error);
                        list_add(&req->list, &dev->rx_reqs);
                        break;
                } else {
                        list_add(&req->list, &dev->rx_reqs_active);
                }
        }
}

static ssize_t
printer_read(struct file *fd, char __user *buf, size_t len, loff_t *ptr)
{
        struct printer_dev              *dev = fd->private_data;
        unsigned long                   flags;
        size_t                          size;
        size_t                          bytes_copied;
        struct usb_request              *req;
        /* This is a pointer to the current USB rx request. */
        struct usb_request              *current_rx_req;
        /* This is the number of bytes in the current rx buffer. */
        size_t                          current_rx_bytes;
        /* This is a pointer to the current rx buffer. */
        u8                              *current_rx_buf;

        if (len == 0)
                return -EINVAL;

        DBG(dev, "printer_read trying to read %d bytes\n", (int)len);

        mutex_lock(&dev->lock_printer_io);
        spin_lock_irqsave(&dev->lock, flags);

        /* We will use this flag later to check if a printer reset happened
         * after we turn interrupts back on.
         */
        dev->reset_printer = 0;

        setup_rx_reqs(dev);

        bytes_copied = 0;
        current_rx_req = dev->current_rx_req;
        current_rx_bytes = dev->current_rx_bytes;
        current_rx_buf = dev->current_rx_buf;
        dev->current_rx_req = NULL;
        dev->current_rx_bytes = 0;
        dev->current_rx_buf = NULL;

        /* Check if there is any data in the read buffers. Please note that
         * current_rx_bytes is the number of bytes in the current rx buffer.
         * If it is zero then check if there are any other rx_buffers that
         * are on the completed list. We are only out of data if all rx
         * buffers are empty.
         */
        if ((current_rx_bytes == 0) &&
                        (likely(list_empty(&dev->rx_buffers)))) {
                /* Turn interrupts back on before sleeping. */
                spin_unlock_irqrestore(&dev->lock, flags);

                /*
                 * If no data is available check if this is a NON-Blocking
                 * call or not.
                 */
                if (fd->f_flags & (O_NONBLOCK|O_NDELAY)) {
                        mutex_unlock(&dev->lock_printer_io);
                        return -EAGAIN;
                }

                /* Sleep until data is available */
                wait_event_interruptible(dev->rx_wait,
                                (likely(!list_empty(&dev->rx_buffers))));
                spin_lock_irqsave(&dev->lock, flags);
        }

        /* We have data to return then copy it to the caller's buffer.*/
        while ((current_rx_bytes || likely(!list_empty(&dev->rx_buffers)))
                        && len) {
                if (current_rx_bytes == 0) {
                        req = container_of(dev->rx_buffers.next,
                                        struct usb_request, list);
                        list_del_init(&req->list);

                        if (req->actual && req->buf) {
                                current_rx_req = req;
                                current_rx_bytes = req->actual;
                                current_rx_buf = req->buf;
                        } else {
                                list_add(&req->list, &dev->rx_reqs);
                                continue;
                        }
                }

                /* Don't leave irqs off while doing memory copies */
                spin_unlock_irqrestore(&dev->lock, flags);

                if (len > current_rx_bytes)
                        size = current_rx_bytes;
                else
                        size = len;

                size -= copy_to_user(buf, current_rx_buf, size);
                bytes_copied += size;
                len -= size;
                buf += size;

                spin_lock_irqsave(&dev->lock, flags);

                /* We've disconnected or reset so return. */
                if (dev->reset_printer) {
                        list_add(&current_rx_req->list, &dev->rx_reqs);
                        spin_unlock_irqrestore(&dev->lock, flags);
                        mutex_unlock(&dev->lock_printer_io);
                        return -EAGAIN;
                }

                /* If we not returning all the data left in this RX request
                 * buffer then adjust the amount of data left in the buffer.
                 * Othewise if we are done with this RX request buffer then
                 * requeue it to get any incoming data from the USB host.
                 */
                if (size < current_rx_bytes) {
                        current_rx_bytes -= size;
                        current_rx_buf += size;
                } else {
                        list_add(&current_rx_req->list, &dev->rx_reqs);
                        current_rx_bytes = 0;
                        current_rx_buf = NULL;
                        current_rx_req = NULL;
                }
        }

        dev->current_rx_req = current_rx_req;
        dev->current_rx_bytes = current_rx_bytes;
        dev->current_rx_buf = current_rx_buf;

        spin_unlock_irqrestore(&dev->lock, flags);
        mutex_unlock(&dev->lock_printer_io);

        DBG(dev, "printer_read returned %d bytes\n", (int)bytes_copied);

        if (bytes_copied)
                return bytes_copied;
        else
                return -EAGAIN;
}

static ssize_t
printer_write(struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
{
        struct printer_dev      *dev = fd->private_data;
        unsigned long           flags;
        size_t                  size;   /* Amount of data in a TX request. */
        size_t                  bytes_copied = 0;
        struct usb_request      *req;

        DBG(dev, "printer_write trying to send %d bytes\n", (int)len);

        if (len == 0)
                return -EINVAL;

        mutex_lock(&dev->lock_printer_io);
        spin_lock_irqsave(&dev->lock, flags);

        /* Check if a printer reset happens while we have interrupts on */
        dev->reset_printer = 0;

        /* Check if there is any available write buffers */
        if (likely(list_empty(&dev->tx_reqs))) {
                /* Turn interrupts back on before sleeping. */
                spin_unlock_irqrestore(&dev->lock, flags);

                /*
                 * If write buffers are available check if this is
                 * a NON-Blocking call or not.
                 */
                if (fd->f_flags & (O_NONBLOCK|O_NDELAY)) {
                        mutex_unlock(&dev->lock_printer_io);
                        return -EAGAIN;
                }

                /* Sleep until a write buffer is available */
                wait_event_interruptible(dev->tx_wait,
                                (likely(!list_empty(&dev->tx_reqs))));
                spin_lock_irqsave(&dev->lock, flags);
        }

        while (likely(!list_empty(&dev->tx_reqs)) && len) {

                if (len > USB_BUFSIZE)
                        size = USB_BUFSIZE;
                else
                        size = len;

                req = container_of(dev->tx_reqs.next, struct usb_request,
                                list);
                list_del_init(&req->list);

                req->complete = tx_complete;
                req->length = size;

                /* Check if we need to send a zero length packet. */
                if (len > size)
                        /* They will be more TX requests so no yet. */
                        req->zero = 0;
                else
                        /* If the data amount is not a multple of the
                         * maxpacket size then send a zero length packet.
                         */
                        req->zero = ((len % dev->in_ep->maxpacket) == 0);

                /* Don't leave irqs off while doing memory copies */
                spin_unlock_irqrestore(&dev->lock, flags);

                if (copy_from_user(req->buf, buf, size)) {
                        list_add(&req->list, &dev->tx_reqs);
                        mutex_unlock(&dev->lock_printer_io);
                        return bytes_copied;
                }

                bytes_copied += size;
                len -= size;
                buf += size;

                spin_lock_irqsave(&dev->lock, flags);

                /* We've disconnected or reset so free the req and buffer */
                if (dev->reset_printer) {
                        list_add(&req->list, &dev->tx_reqs);
                        spin_unlock_irqrestore(&dev->lock, flags);
                        mutex_unlock(&dev->lock_printer_io);
                        return -EAGAIN;
                }

                if (usb_ep_queue(dev->in_ep, req, GFP_ATOMIC)) {
                        list_add(&req->list, &dev->tx_reqs);
                        spin_unlock_irqrestore(&dev->lock, flags);
                        mutex_unlock(&dev->lock_printer_io);
                        return -EAGAIN;
                }

                list_add(&req->list, &dev->tx_reqs_active);

        }

        spin_unlock_irqrestore(&dev->lock, flags);
        mutex_unlock(&dev->lock_printer_io);

        DBG(dev, "printer_write sent %d bytes\n", (int)bytes_copied);

        if (bytes_copied) {
                return bytes_copied;
        } else {
                return -EAGAIN;
        }
}

static int
printer_fsync(struct file *fd, loff_t start, loff_t end, int datasync)
{
        struct printer_dev      *dev = fd->private_data;
        struct inode *inode = fd->f_path.dentry->d_inode;
        unsigned long           flags;
        int                     tx_list_empty;

        mutex_lock(&inode->i_mutex);
        spin_lock_irqsave(&dev->lock, flags);
        tx_list_empty = (likely(list_empty(&dev->tx_reqs)));
        spin_unlock_irqrestore(&dev->lock, flags);

        if (!tx_list_empty) {
                /* Sleep until all data has been sent */
                wait_event_interruptible(dev->tx_flush_wait,
                                (likely(list_empty(&dev->tx_reqs_active))));
        }
        mutex_unlock(&inode->i_mutex);

        return 0;
}

static unsigned int
printer_poll(struct file *fd, poll_table *wait)
{
        struct printer_dev      *dev = fd->private_data;
        unsigned long           flags;
        int                     status = 0;

        mutex_lock(&dev->lock_printer_io);
        spin_lock_irqsave(&dev->lock, flags);
        setup_rx_reqs(dev);
        spin_unlock_irqrestore(&dev->lock, flags);
        mutex_unlock(&dev->lock_printer_io);

        poll_wait(fd, &dev->rx_wait, wait);
        poll_wait(fd, &dev->tx_wait, wait);

        spin_lock_irqsave(&dev->lock, flags);
        if (likely(!list_empty(&dev->tx_reqs)))
                status |= POLLOUT | POLLWRNORM;

        if (likely(dev->current_rx_bytes) ||
                        likely(!list_empty(&dev->rx_buffers)))
                status |= POLLIN | POLLRDNORM;

        spin_unlock_irqrestore(&dev->lock, flags);

        return status;
}

static long
printer_ioctl(struct file *fd, unsigned int code, unsigned long arg)
{
        struct printer_dev      *dev = fd->private_data;
        unsigned long           flags;
        int                     status = 0;

        DBG(dev, "printer_ioctl: cmd=0x%4.4x, arg=%lu\n", code, arg);

        /* handle ioctls */

        spin_lock_irqsave(&dev->lock, flags);

        switch (code) {
        case GADGET_GET_PRINTER_STATUS:
                status = (int)dev->printer_status;
                break;
        case GADGET_SET_PRINTER_STATUS:
                dev->printer_status = (u8)arg;
                break;
        default:
                /* could not handle ioctl */
                DBG(dev, "printer_ioctl: ERROR cmd=0x%4.4xis not supported\n",
                                code);
                status = -ENOTTY;
        }

        spin_unlock_irqrestore(&dev->lock, flags);

        return status;
}

/* used after endpoint configuration */
static const struct file_operations printer_io_operations = {
        .owner =        THIS_MODULE,
        .open =         printer_open,
        .read =         printer_read,
        .write =        printer_write,
        .fsync =        printer_fsync,
        .poll =         printer_poll,
        .unlocked_ioctl = printer_ioctl,
        .release =      printer_close,
        .llseek =       noop_llseek,
};

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

static int
set_printer_interface(struct printer_dev *dev)
{
        int                     result = 0;

        dev->in_ep->desc = ep_desc(dev->gadget, &hs_ep_in_desc, &fs_ep_in_desc);
        dev->in_ep->driver_data = dev;

        dev->out_ep->desc = ep_desc(dev->gadget, &hs_ep_out_desc,
                                    &fs_ep_out_desc);
        dev->out_ep->driver_data = dev;

        result = usb_ep_enable(dev->in_ep);
        if (result != 0) {
                DBG(dev, "enable %s --> %d\n", dev->in_ep->name, result);
                goto done;
        }

        result = usb_ep_enable(dev->out_ep);
        if (result != 0) {
                DBG(dev, "enable %s --> %d\n", dev->in_ep->name, result);
                goto done;
        }

done:
        /* on error, disable any endpoints  */
        if (result != 0) {
                (void) usb_ep_disable(dev->in_ep);
                (void) usb_ep_disable(dev->out_ep);
                dev->in_ep->desc = NULL;
                dev->out_ep->desc = NULL;
        }

        /* caller is responsible for cleanup on error */
        return result;
}

static void printer_reset_interface(struct printer_dev *dev)
{
        if (dev->interface < 0)
                return;

        DBG(dev, "%s\n", __func__);

        if (dev->in_ep->desc)
                usb_ep_disable(dev->in_ep);

        if (dev->out_ep->desc)
                usb_ep_disable(dev->out_ep);

        dev->in_ep->desc = NULL;
        dev->out_ep->desc = NULL;
        dev->interface = -1;
}

/* change our operational config.  must agree with the code
 * that returns config descriptors, and altsetting code.
 */
static int
printer_set_config(struct printer_dev *dev, unsigned number)
{
        int                     result = 0;
        struct usb_gadget       *gadget = dev->gadget;

        switch (number) {
        case DEV_CONFIG_VALUE:
                result = 0;
                break;
        default:
                result = -EINVAL;
                /* FALL THROUGH */
        case 0:
                break;
        }

        if (result) {
                usb_gadget_vbus_draw(dev->gadget,
                                dev->gadget->is_otg ? 8 : 100);
        } else {
                unsigned power;

                power = 2 * config_desc.bMaxPower;
                usb_gadget_vbus_draw(dev->gadget, power);

                dev->config = number;
                INFO(dev, "%s config #%d: %d mA, %s\n",
                     usb_speed_string(gadget->speed),
                     number, power, driver_desc);
        }
        return result;
}

static int
config_buf(enum usb_device_speed speed, u8 *buf, u8 type, unsigned index,
                int is_otg)
{
        int                                     len;
        const struct usb_descriptor_header      **function;
#ifdef CONFIG_USB_GADGET_DUALSPEED
        int                                     hs = (speed == USB_SPEED_HIGH);

        if (type == USB_DT_OTHER_SPEED_CONFIG)
                hs = !hs;

        if (hs) {
                function = hs_printer_function;
        } else {
                function = fs_printer_function;
        }
#else
        function = fs_printer_function;
#endif

        if (index >= device_desc.bNumConfigurations)
                return -EINVAL;

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

        len = usb_gadget_config_buf(&config_desc, buf, USB_DESC_BUFSIZE,
                        function);
        if (len < 0)
                return len;
        ((struct usb_config_descriptor *) buf)->bDescriptorType = type;
        return len;
}

/* Change our operational Interface. */
static int
set_interface(struct printer_dev *dev, unsigned number)
{
        int                     result = 0;

        /* Free the current interface */
        switch (dev->interface) {
        case PRINTER_INTERFACE:
                printer_reset_interface(dev);
                break;
        }

        switch (number) {
        case PRINTER_INTERFACE:
                result = set_printer_interface(dev);
                if (result) {
                        printer_reset_interface(dev);
                } else {
                        dev->interface = PRINTER_INTERFACE;
                }
                break;
        default:
                result = -EINVAL;
                /* FALL THROUGH */
        }

        if (!result)
                INFO(dev, "Using interface %x\n", number);

        return result;
}

static void printer_setup_complete(struct usb_ep *ep, struct usb_request *req)
{
        if (req->status || req->actual != req->length)
                DBG((struct printer_dev *) ep->driver_data,
                                "setup complete --> %d, %d/%d\n",
                                req->status, req->actual, req->length);
}

static void printer_soft_reset(struct printer_dev *dev)
{
        struct usb_request      *req;

        INFO(dev, "Received Printer Reset Request\n");

        if (usb_ep_disable(dev->in_ep))
                DBG(dev, "Failed to disable USB in_ep\n");
        if (usb_ep_disable(dev->out_ep))
                DBG(dev, "Failed to disable USB out_ep\n");

        if (dev->current_rx_req != NULL) {
                list_add(&dev->current_rx_req->list, &dev->rx_reqs);
                dev->current_rx_req = NULL;
        }
        dev->current_rx_bytes = 0;
        dev->current_rx_buf = NULL;
        dev->reset_printer = 1;

        while (likely(!(list_empty(&dev->rx_buffers)))) {
                req = container_of(dev->rx_buffers.next, struct usb_request,
                                list);
                list_del_init(&req->list);
                list_add(&req->list, &dev->rx_reqs);
        }

        while (likely(!(list_empty(&dev->rx_reqs_active)))) {
                req = container_of(dev->rx_buffers.next, struct usb_request,
                                list);
                list_del_init(&req->list);
                list_add(&req->list, &dev->rx_reqs);
        }

        while (likely(!(list_empty(&dev->tx_reqs_active)))) {
                req = container_of(dev->tx_reqs_active.next,
                                struct usb_request, list);
                list_del_init(&req->list);
                list_add(&req->list, &dev->tx_reqs);
        }

        if (usb_ep_enable(dev->in_ep))
                DBG(dev, "Failed to enable USB in_ep\n");
        if (usb_ep_enable(dev->out_ep))
                DBG(dev, "Failed to enable USB out_ep\n");

        wake_up_interruptible(&dev->rx_wait);
        wake_up_interruptible(&dev->tx_wait);
        wake_up_interruptible(&dev->tx_flush_wait);
}

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

/*
 * The setup() callback implements all the ep0 functionality that's not
 * handled lower down.
 */
static int
printer_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
{
        struct printer_dev      *dev = get_gadget_data(gadget);
        struct usb_request      *req = dev->req;
        int                     value = -EOPNOTSUPP;
        u16                     wIndex = le16_to_cpu(ctrl->wIndex);
        u16                     wValue = le16_to_cpu(ctrl->wValue);
        u16                     wLength = le16_to_cpu(ctrl->wLength);

        DBG(dev, "ctrl req%02x.%02x v%04x i%04x l%d\n",
                ctrl->bRequestType, ctrl->bRequest, wValue, wIndex, wLength);

        req->complete = printer_setup_complete;

        switch (ctrl->bRequestType&USB_TYPE_MASK) {

        case USB_TYPE_STANDARD:
                switch (ctrl->bRequest) {

                case USB_REQ_GET_DESCRIPTOR:
                        if (ctrl->bRequestType != USB_DIR_IN)
                                break;
                        switch (wValue >> 8) {

                        case USB_DT_DEVICE:
                                device_desc.bMaxPacketSize0 =
                                        gadget->ep0->maxpacket;
                                value = min(wLength, (u16) sizeof device_desc);
                                memcpy(req->buf, &device_desc, value);
                                break;
#ifdef CONFIG_USB_GADGET_DUALSPEED
                        case USB_DT_DEVICE_QUALIFIER:
                                if (!gadget_is_dualspeed(gadget))
                                        break;
                                /*
                                 * assumes ep0 uses the same value for both
                                 * speeds
                                 */
                                dev_qualifier.bMaxPacketSize0 =
                                        gadget->ep0->maxpacket;
                                value = min(wLength,
                                                (u16) sizeof dev_qualifier);
                                memcpy(req->buf, &dev_qualifier, value);
                                break;

                        case USB_DT_OTHER_SPEED_CONFIG:
                                if (!gadget_is_dualspeed(gadget))
                                        break;
                                /* FALLTHROUGH */
#endif /* CONFIG_USB_GADGET_DUALSPEED */
                        case USB_DT_CONFIG:
                                value = config_buf(gadget->speed, req->buf,
                                                wValue >> 8,
                                                wValue & 0xff,
                                                gadget->is_otg);
                                if (value >= 0)
                                        value = min(wLength, (u16) value);
                                break;

                        case USB_DT_STRING:
                                value = usb_gadget_get_string(&stringtab,
                                                wValue & 0xff, req->buf);
                                if (value >= 0)
                                        value = min(wLength, (u16) value);
                                break;
                        }
                        break;

                case USB_REQ_SET_CONFIGURATION:
                        if (ctrl->bRequestType != 0)
                                break;
                        if (gadget->a_hnp_support)
                                DBG(dev, "HNP available\n");
                        else if (gadget->a_alt_hnp_support)
                                DBG(dev, "HNP needs a different root port\n");
                        value = printer_set_config(dev, wValue);
                        if (!value)
                                value = set_interface(dev, PRINTER_INTERFACE);
                        break;
                case USB_REQ_GET_CONFIGURATION:
                        if (ctrl->bRequestType != USB_DIR_IN)
                                break;
                        *(u8 *)req->buf = dev->config;
                        value = min(wLength, (u16) 1);
                        break;

                case USB_REQ_SET_INTERFACE:
                        if (ctrl->bRequestType != USB_RECIP_INTERFACE ||
                                        !dev->config)
                                break;

                        value = set_interface(dev, PRINTER_INTERFACE);
                        break;
                case USB_REQ_GET_INTERFACE:
                        if (ctrl->bRequestType !=
                                        (USB_DIR_IN|USB_RECIP_INTERFACE)
                                        || !dev->config)
                                break;

                        *(u8 *)req->buf = dev->interface;
                        value = min(wLength, (u16) 1);
                        break;

                default:
                        goto unknown;
                }
                break;

        case USB_TYPE_CLASS:
                switch (ctrl->bRequest) {
                case 0: /* Get the IEEE-1284 PNP String */
                        /* Only one printer interface is supported. */
                        if ((wIndex>>8) != PRINTER_INTERFACE)
                                break;

                        value = (pnp_string[0]<<8)|pnp_string[1];
                        memcpy(req->buf, pnp_string, value);
                        DBG(dev, "1284 PNP String: %x %s\n", value,
                                        &pnp_string[2]);
                        break;

                case 1: /* Get Port Status */
                        /* Only one printer interface is supported. */
                        if (wIndex != PRINTER_INTERFACE)
                                break;

                        *(u8 *)req->buf = dev->printer_status;
                        value = min(wLength, (u16) 1);
                        break;

                case 2: /* Soft Reset */
                        /* Only one printer interface is supported. */
                        if (wIndex != PRINTER_INTERFACE)
                                break;

                        printer_soft_reset(dev);

                        value = 0;
                        break;

                default:
                        goto unknown;
                }
                break;

        default:
unknown:
                VDBG(dev,
                        "unknown ctrl req%02x.%02x v%04x i%04x l%d\n",
                        ctrl->bRequestType, ctrl->bRequest,
                        wValue, wIndex, wLength);
                break;
        }

        /* respond with data transfer before status phase? */
        if (value >= 0) {
                req->length = value;
                req->zero = value < wLength;
                value = usb_ep_queue(gadget->ep0, req, GFP_ATOMIC);
                if (value < 0) {
                        DBG(dev, "ep_queue --> %d\n", value);
                        req->status = 0;
                        printer_setup_complete(gadget->ep0, req);
                }
        }

        /* host either stalls (value < 0) or reports success */
        return value;
}

static void
printer_disconnect(struct usb_gadget *gadget)
{
        struct printer_dev      *dev = get_gadget_data(gadget);
        unsigned long           flags;

        DBG(dev, "%s\n", __func__);

        spin_lock_irqsave(&dev->lock, flags);

        printer_reset_interface(dev);

        spin_unlock_irqrestore(&dev->lock, flags);
}

static void
printer_unbind(struct usb_gadget *gadget)
{
        struct printer_dev      *dev = get_gadget_data(gadget);
        struct usb_request      *req;


        DBG(dev, "%s\n", __func__);

        /* Remove sysfs files */
        device_destroy(usb_gadget_class, g_printer_devno);

        /* Remove Character Device */
        cdev_del(&dev->printer_cdev);

        /* we must already have been disconnected ... no i/o may be active */
        WARN_ON(!list_empty(&dev->tx_reqs_active));
        WARN_ON(!list_empty(&dev->rx_reqs_active));

        /* Free all memory for this driver. */
        while (!list_empty(&dev->tx_reqs)) {
                req = container_of(dev->tx_reqs.next, struct usb_request,
                                list);
                list_del(&req->list);
                printer_req_free(dev->in_ep, req);
        }

        if (dev->current_rx_req != NULL)
                printer_req_free(dev->out_ep, dev->current_rx_req);

        while (!list_empty(&dev->rx_reqs)) {
                req = container_of(dev->rx_reqs.next,
                                struct usb_request, list);
                list_del(&req->list);
                printer_req_free(dev->out_ep, req);
        }

        while (!list_empty(&dev->rx_buffers)) {
                req = container_of(dev->rx_buffers.next,
                                struct usb_request, list);
                list_del(&req->list);
                printer_req_free(dev->out_ep, req);
        }

        if (dev->req) {
                printer_req_free(gadget->ep0, dev->req);
                dev->req = NULL;
        }

        set_gadget_data(gadget, NULL);
}

static int __init
printer_bind(struct usb_gadget *gadget)
{
        struct printer_dev      *dev;
        struct usb_ep           *in_ep, *out_ep;
        int                     status = -ENOMEM;
        int                     gcnum;
        size_t                  len;
        u32                     i;
        struct usb_request      *req;

        dev = &usb_printer_gadget;


        /* Setup the sysfs files for the printer gadget. */
        dev->pdev = device_create(usb_gadget_class, NULL, g_printer_devno,
                                  NULL, "g_printer");
        if (IS_ERR(dev->pdev)) {
                ERROR(dev, "Failed to create device: g_printer\n");
                goto fail;
        }

        /*
         * Register a character device as an interface to a user mode
         * program that handles the printer specific functionality.
         */
        cdev_init(&dev->printer_cdev, &printer_io_operations);
        dev->printer_cdev.owner = THIS_MODULE;
        status = cdev_add(&dev->printer_cdev, g_printer_devno, 1);
        if (status) {
                ERROR(dev, "Failed to open char device\n");
                goto fail;
        }

        gcnum = usb_gadget_controller_number(gadget);
        if (gcnum >= 0) {
                device_desc.bcdDevice = cpu_to_le16(0x0200 + gcnum);
        } else {
                dev_warn(&gadget->dev, "controller '%s' not recognized\n",
                        gadget->name);
                /* unrecognized, but safe unless bulk is REALLY quirky */
                device_desc.bcdDevice =
                        cpu_to_le16(0xFFFF);
        }
        snprintf(manufacturer, sizeof(manufacturer), "%s %s with %s",
                init_utsname()->sysname, init_utsname()->release,
                gadget->name);

        device_desc.idVendor =
                cpu_to_le16(PRINTER_VENDOR_NUM);
        device_desc.idProduct =
                cpu_to_le16(PRINTER_PRODUCT_NUM);

        /* support optional vendor/distro customization */
        if (idVendor) {
                if (!idProduct) {
                        dev_err(&gadget->dev, "idVendor needs idProduct!\n");
                        return -ENODEV;
                }
                device_desc.idVendor = cpu_to_le16(idVendor);
                device_desc.idProduct = cpu_to_le16(idProduct);
                if (bcdDevice)
                        device_desc.bcdDevice = cpu_to_le16(bcdDevice);
        }

        if (iManufacturer)
                strlcpy(manufacturer, iManufacturer, sizeof manufacturer);

        if (iProduct)
                strlcpy(product_desc, iProduct, sizeof product_desc);

        if (iSerialNum)
                strlcpy(serial_num, iSerialNum, sizeof serial_num);

        if (iPNPstring)
                strlcpy(&pnp_string[2], iPNPstring, (sizeof pnp_string)-2);

        len = strlen(pnp_string);
        pnp_string[0] = (len >> 8) & 0xFF;
        pnp_string[1] = len & 0xFF;

        /* all we really need is bulk IN/OUT */
        usb_ep_autoconfig_reset(gadget);
        in_ep = usb_ep_autoconfig(gadget, &fs_ep_in_desc);
        if (!in_ep) {
autoconf_fail:
                dev_err(&gadget->dev, "can't autoconfigure on %s\n",
                        gadget->name);
                return -ENODEV;
        }
        in_ep->driver_data = in_ep;     /* claim */

        out_ep = usb_ep_autoconfig(gadget, &fs_ep_out_desc);
        if (!out_ep)
                goto autoconf_fail;
        out_ep->driver_data = out_ep;   /* claim */

#ifdef  CONFIG_USB_GADGET_DUALSPEED
        /* assumes that all endpoints are dual-speed */
        hs_ep_in_desc.bEndpointAddress = fs_ep_in_desc.bEndpointAddress;
        hs_ep_out_desc.bEndpointAddress = fs_ep_out_desc.bEndpointAddress;
#endif  /* DUALSPEED */

        usb_gadget_set_selfpowered(gadget);

        if (gadget->is_otg) {
                otg_desc.bmAttributes |= USB_OTG_HNP,
                config_desc.bmAttributes |= USB_CONFIG_ATT_WAKEUP;
        }

        spin_lock_init(&dev->lock);
        mutex_init(&dev->lock_printer_io);
        INIT_LIST_HEAD(&dev->tx_reqs);
        INIT_LIST_HEAD(&dev->tx_reqs_active);
        INIT_LIST_HEAD(&dev->rx_reqs);
        INIT_LIST_HEAD(&dev->rx_reqs_active);
        INIT_LIST_HEAD(&dev->rx_buffers);
        init_waitqueue_head(&dev->rx_wait);
        init_waitqueue_head(&dev->tx_wait);
        init_waitqueue_head(&dev->tx_flush_wait);

        dev->config = 0;
        dev->interface = -1;
        dev->printer_cdev_open = 0;
        dev->printer_status = PRINTER_NOT_ERROR;
        dev->current_rx_req = NULL;
        dev->current_rx_bytes = 0;
        dev->current_rx_buf = NULL;

        dev->in_ep = in_ep;
        dev->out_ep = out_ep;

        /* preallocate control message data and buffer */
        dev->req = printer_req_alloc(gadget->ep0, USB_DESC_BUFSIZE,
                        GFP_KERNEL);
        if (!dev->req) {
                status = -ENOMEM;
                goto fail;
        }

        for (i = 0; i < QLEN; i++) {
                req = printer_req_alloc(dev->in_ep, USB_BUFSIZE, GFP_KERNEL);
                if (!req) {
                        while (!list_empty(&dev->tx_reqs)) {
                                req = container_of(dev->tx_reqs.next,
                                                struct usb_request, list);
                                list_del(&req->list);
                                printer_req_free(dev->in_ep, req);
                        }
                        return -ENOMEM;
                }
                list_add(&req->list, &dev->tx_reqs);
        }

        for (i = 0; i < QLEN; i++) {
                req = printer_req_alloc(dev->out_ep, USB_BUFSIZE, GFP_KERNEL);
                if (!req) {
                        while (!list_empty(&dev->rx_reqs)) {
                                req = container_of(dev->rx_reqs.next,
                                                struct usb_request, list);
                                list_del(&req->list);
                                printer_req_free(dev->out_ep, req);
                        }
                        return -ENOMEM;
                }
                list_add(&req->list, &dev->rx_reqs);
        }

        dev->req->complete = printer_setup_complete;

        /* finish hookup to lower layer ... */
        dev->gadget = gadget;
        set_gadget_data(gadget, dev);
        gadget->ep0->driver_data = dev;

        INFO(dev, "%s, version: " DRIVER_VERSION "\n", driver_desc);
        INFO(dev, "using %s, OUT %s IN %s\n", gadget->name, out_ep->name,
                        in_ep->name);

        return 0;

fail:
        printer_unbind(gadget);
        return status;
}

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

static struct usb_gadget_driver printer_driver = {
        .max_speed      = DEVSPEED,

        .function       = (char *) driver_desc,
        .unbind         = printer_unbind,

        .setup          = printer_setup,
        .disconnect     = printer_disconnect,

        .driver         = {
                .name           = (char *) shortname,
                .owner          = THIS_MODULE,
        },
};

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR("Craig Nadler");
MODULE_LICENSE("GPL");

static int __init
init(void)
{
        int status;

        usb_gadget_class = class_create(THIS_MODULE, "usb_printer_gadget");
        if (IS_ERR(usb_gadget_class)) {
                status = PTR_ERR(usb_gadget_class);
                ERROR(dev, "unable to create usb_gadget class %d\n", status);
                return status;
        }

        status = alloc_chrdev_region(&g_printer_devno, 0, 1,
                        "USB printer gadget");
        if (status) {
                ERROR(dev, "alloc_chrdev_region %d\n", status);
                class_destroy(usb_gadget_class);
                return status;
        }

        status = usb_gadget_probe_driver(&printer_driver, printer_bind);
        if (status) {
                class_destroy(usb_gadget_class);
                unregister_chrdev_region(g_printer_devno, 1);
                DBG(dev, "usb_gadget_probe_driver %x\n", status);
        }

        return status;
}
module_init(init);

static void __exit
cleanup(void)
{
        int status;

        mutex_lock(&usb_printer_gadget.lock_printer_io);
        status = usb_gadget_unregister_driver(&printer_driver);
        if (status)
                ERROR(dev, "usb_gadget_unregister_driver %x\n", status);

        unregister_chrdev_region(g_printer_devno, 1);
        class_destroy(usb_gadget_class);
        mutex_unlock(&usb_printer_gadget.lock_printer_io);
}
module_exit(cleanup);