Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / drivers / usb / gadget / function / f_printer.c
diff --git a/kernel/drivers/usb/gadget/function/f_printer.c b/kernel/drivers/usb/gadget/function/f_printer.c
new file mode 100644 (file)
index 0000000..44173df
--- /dev/null
@@ -0,0 +1,1471 @@
+/*
+ * f_printer.c - USB printer function driver
+ *
+ * Copied from drivers/usb/gadget/legacy/printer.c,
+ * which was:
+ *
+ * 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/idr.h>
+#include <linux/timer.h>
+#include <linux/list.h>
+#include <linux/interrupt.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 <linux/uaccess.h>
+#include <asm/unaligned.h>
+
+#include <linux/usb/ch9.h>
+#include <linux/usb/composite.h>
+#include <linux/usb/gadget.h>
+#include <linux/usb/g_printer.h>
+
+#include "u_printer.h"
+
+#define PNP_STRING_LEN         1024
+#define PRINTER_MINORS         4
+#define GET_DEVICE_ID          0
+#define GET_PORT_STATUS                1
+#define SOFT_RESET             2
+
+static int major, minors;
+static struct class *usb_gadget_class;
+static DEFINE_IDA(printer_ida);
+static DEFINE_MUTEX(printer_ida_lock); /* protects access do printer_ida */
+
+/*-------------------------------------------------------------------------*/
+
+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;
+       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;
+       int                     minor;
+       struct cdev             printer_cdev;
+       u8                      printer_cdev_open;
+       wait_queue_head_t       wait;
+       unsigned                q_len;
+       char                    *pnp_string;    /* We don't own memory! */
+       struct usb_function     function;
+};
+
+static inline struct printer_dev *func_to_printer(struct usb_function *f)
+{
+       return container_of(f, struct printer_dev, function);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * DESCRIPTORS ... most are static, but strings and (full) configuration
+ * descriptors are built on demand.
+ */
+
+/* holds our biggest descriptor */
+#define USB_DESC_BUFSIZE               256
+#define USB_BUFSIZE                    8192
+
+static struct usb_interface_descriptor intf_desc = {
+       .bLength =              sizeof(intf_desc),
+       .bDescriptorType =      USB_DT_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 struct usb_descriptor_header *fs_printer_function[] = {
+       (struct usb_descriptor_header *) &intf_desc,
+       (struct usb_descriptor_header *) &fs_ep_in_desc,
+       (struct usb_descriptor_header *) &fs_ep_out_desc,
+       NULL
+};
+
+/*
+ * 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 struct usb_descriptor_header *hs_printer_function[] = {
+       (struct usb_descriptor_header *) &intf_desc,
+       (struct usb_descriptor_header *) &hs_ep_in_desc,
+       (struct usb_descriptor_header *) &hs_ep_out_desc,
+       NULL
+};
+
+/*
+ * Added endpoint descriptors for 3.0 devices
+ */
+
+static struct usb_endpoint_descriptor ss_ep_in_desc = {
+       .bLength =              USB_DT_ENDPOINT_SIZE,
+       .bDescriptorType =      USB_DT_ENDPOINT,
+       .bmAttributes =         USB_ENDPOINT_XFER_BULK,
+       .wMaxPacketSize =       cpu_to_le16(1024),
+};
+
+static struct usb_ss_ep_comp_descriptor ss_ep_in_comp_desc = {
+       .bLength =              sizeof(ss_ep_in_comp_desc),
+       .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
+};
+
+static struct usb_endpoint_descriptor ss_ep_out_desc = {
+       .bLength =              USB_DT_ENDPOINT_SIZE,
+       .bDescriptorType =      USB_DT_ENDPOINT,
+       .bmAttributes =         USB_ENDPOINT_XFER_BULK,
+       .wMaxPacketSize =       cpu_to_le16(1024),
+};
+
+static struct usb_ss_ep_comp_descriptor ss_ep_out_comp_desc = {
+       .bLength =              sizeof(ss_ep_out_comp_desc),
+       .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
+};
+
+static struct usb_descriptor_header *ss_printer_function[] = {
+       (struct usb_descriptor_header *) &intf_desc,
+       (struct usb_descriptor_header *) &ss_ep_in_desc,
+       (struct usb_descriptor_header *) &ss_ep_in_comp_desc,
+       (struct usb_descriptor_header *) &ss_ep_out_desc,
+       (struct usb_descriptor_header *) &ss_ep_out_comp_desc,
+       NULL
+};
+
+/* maxpacket and other transfer characteristics vary by speed. */
+static inline struct usb_endpoint_descriptor *ep_desc(struct usb_gadget *gadget,
+                                       struct usb_endpoint_descriptor *fs,
+                                       struct usb_endpoint_descriptor *hs,
+                                       struct usb_endpoint_descriptor *ss)
+{
+       switch (gadget->speed) {
+       case USB_SPEED_SUPER:
+               return ss;
+       case USB_SPEED_HIGH:
+               return hs;
+       default:
+               return fs;
+       }
+}
+
+/*-------------------------------------------------------------------------*/
+
+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;
+
+       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);
+       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;
+
+               /* here, we unlock, and only unlock, to avoid deadlock. */
+               spin_unlock(&dev->lock);
+               error = usb_ep_queue(dev->out_ep, req, GFP_ATOMIC);
+               spin_lock(&dev->lock);
+               if (error) {
+                       DBG(dev, "rx submit --> %d\n", error);
+                       list_add(&req->list, &dev->rx_reqs);
+                       break;
+               }
+               /* if the req is empty, then add it into dev->rx_reqs_active. */
+               else if (list_empty(&req->list))
+                       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 multiple 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 = file_inode(fd);
+       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, &fs_ep_in_desc, &hs_ep_in_desc,
+                               &ss_ep_in_desc);
+       dev->in_ep->driver_data = dev;
+
+       dev->out_ep->desc = ep_desc(dev->gadget, &fs_ep_out_desc,
+                                   &hs_ep_out_desc, &ss_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 Interface. */
+static int set_interface(struct printer_dev *dev, unsigned number)
+{
+       int                     result = 0;
+
+       /* Free the current interface */
+       printer_reset_interface(dev);
+
+       result = set_printer_interface(dev);
+       if (result)
+               printer_reset_interface(dev);
+       else
+               dev->interface = number;
+
+       if (!result)
+               INFO(dev, "Using interface %x\n", number);
+
+       return result;
+}
+
+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);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static bool gprinter_req_match(struct usb_function *f,
+                              const struct usb_ctrlrequest *ctrl)
+{
+       struct printer_dev      *dev = func_to_printer(f);
+       u16                     w_index = le16_to_cpu(ctrl->wIndex);
+       u16                     w_value = le16_to_cpu(ctrl->wValue);
+       u16                     w_length = le16_to_cpu(ctrl->wLength);
+
+       if ((ctrl->bRequestType & USB_RECIP_MASK) != USB_RECIP_INTERFACE ||
+           (ctrl->bRequestType & USB_TYPE_MASK) != USB_TYPE_CLASS)
+               return false;
+
+       switch (ctrl->bRequest) {
+       case GET_DEVICE_ID:
+               w_index >>= 8;
+               if (w_length <= PNP_STRING_LEN &&
+                   (USB_DIR_IN & ctrl->bRequestType))
+                       break;
+               return false;
+       case GET_PORT_STATUS:
+               if (!w_value && w_length == 1 &&
+                   (USB_DIR_IN & ctrl->bRequestType))
+                       break;
+               return false;
+       case SOFT_RESET:
+               if (!w_value && !w_length &&
+                  !(USB_DIR_IN & ctrl->bRequestType))
+                       break;
+               /* fall through */
+       default:
+               return false;
+       }
+       return w_index == dev->interface;
+}
+
+/*
+ * The setup() callback implements all the ep0 functionality that's not
+ * handled lower down.
+ */
+static int printer_func_setup(struct usb_function *f,
+               const struct usb_ctrlrequest *ctrl)
+{
+       struct printer_dev *dev = func_to_printer(f);
+       struct usb_composite_dev *cdev = f->config->cdev;
+       struct usb_request      *req = cdev->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);
+
+       switch (ctrl->bRequestType&USB_TYPE_MASK) {
+       case USB_TYPE_CLASS:
+               switch (ctrl->bRequest) {
+               case GET_DEVICE_ID: /* Get the IEEE-1284 PNP String */
+                       /* Only one printer interface is supported. */
+                       if ((wIndex>>8) != dev->interface)
+                               break;
+
+                       value = (dev->pnp_string[0] << 8) | dev->pnp_string[1];
+                       memcpy(req->buf, dev->pnp_string, value);
+                       DBG(dev, "1284 PNP String: %x %s\n", value,
+                                       &dev->pnp_string[2]);
+                       break;
+
+               case GET_PORT_STATUS: /* Get Port Status */
+                       /* Only one printer interface is supported. */
+                       if (wIndex != dev->interface)
+                               break;
+
+                       *(u8 *)req->buf = dev->printer_status;
+                       value = min_t(u16, wLength, 1);
+                       break;
+
+               case SOFT_RESET: /* Soft Reset */
+                       /* Only one printer interface is supported. */
+                       if (wIndex != dev->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;
+       }
+       /* host either stalls (value < 0) or reports success */
+       if (value >= 0) {
+               req->length = value;
+               req->zero = value < wLength;
+               value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
+               if (value < 0) {
+                       ERROR(dev, "%s:%d Error!\n", __func__, __LINE__);
+                       req->status = 0;
+               }
+       }
+       return value;
+}
+
+static int printer_func_bind(struct usb_configuration *c,
+               struct usb_function *f)
+{
+       struct usb_gadget *gadget = c->cdev->gadget;
+       struct printer_dev *dev = func_to_printer(f);
+       struct device *pdev;
+       struct usb_composite_dev *cdev = c->cdev;
+       struct usb_ep *in_ep;
+       struct usb_ep *out_ep = NULL;
+       struct usb_request *req;
+       dev_t devt;
+       int id;
+       int ret;
+       u32 i;
+
+       id = usb_interface_id(c, f);
+       if (id < 0)
+               return id;
+       intf_desc.bInterfaceNumber = id;
+
+       /* finish hookup to lower layer ... */
+       dev->gadget = gadget;
+
+       /* all we really need is bulk IN/OUT */
+       in_ep = usb_ep_autoconfig(cdev->gadget, &fs_ep_in_desc);
+       if (!in_ep) {
+autoconf_fail:
+               dev_err(&cdev->gadget->dev, "can't autoconfigure on %s\n",
+                       cdev->gadget->name);
+               return -ENODEV;
+       }
+       in_ep->driver_data = in_ep;     /* claim */
+
+       out_ep = usb_ep_autoconfig(cdev->gadget, &fs_ep_out_desc);
+       if (!out_ep)
+               goto autoconf_fail;
+       out_ep->driver_data = out_ep;   /* claim */
+
+       /* 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;
+       ss_ep_in_desc.bEndpointAddress = fs_ep_in_desc.bEndpointAddress;
+       ss_ep_out_desc.bEndpointAddress = fs_ep_out_desc.bEndpointAddress;
+
+       ret = usb_assign_descriptors(f, fs_printer_function,
+                       hs_printer_function, ss_printer_function);
+       if (ret)
+               return ret;
+
+       dev->in_ep = in_ep;
+       dev->out_ep = out_ep;
+
+       ret = -ENOMEM;
+       for (i = 0; i < dev->q_len; i++) {
+               req = printer_req_alloc(dev->in_ep, USB_BUFSIZE, GFP_KERNEL);
+               if (!req)
+                       goto fail_tx_reqs;
+               list_add(&req->list, &dev->tx_reqs);
+       }
+
+       for (i = 0; i < dev->q_len; i++) {
+               req = printer_req_alloc(dev->out_ep, USB_BUFSIZE, GFP_KERNEL);
+               if (!req)
+                       goto fail_rx_reqs;
+               list_add(&req->list, &dev->rx_reqs);
+       }
+
+       /* Setup the sysfs files for the printer gadget. */
+       devt = MKDEV(major, dev->minor);
+       pdev = device_create(usb_gadget_class, NULL, devt,
+                                 NULL, "g_printer%d", dev->minor);
+       if (IS_ERR(pdev)) {
+               ERROR(dev, "Failed to create device: g_printer\n");
+               ret = PTR_ERR(pdev);
+               goto fail_rx_reqs;
+       }
+
+       /*
+        * 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;
+       ret = cdev_add(&dev->printer_cdev, devt, 1);
+       if (ret) {
+               ERROR(dev, "Failed to open char device\n");
+               goto fail_cdev_add;
+       }
+
+       return 0;
+
+fail_cdev_add:
+       device_destroy(usb_gadget_class, devt);
+
+fail_rx_reqs:
+       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);
+       }
+
+fail_tx_reqs:
+       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 ret;
+
+}
+
+static int printer_func_set_alt(struct usb_function *f,
+               unsigned intf, unsigned alt)
+{
+       struct printer_dev *dev = func_to_printer(f);
+       int ret = -ENOTSUPP;
+
+       if (!alt)
+               ret = set_interface(dev, intf);
+
+       return ret;
+}
+
+static void printer_func_disable(struct usb_function *f)
+{
+       struct printer_dev *dev = func_to_printer(f);
+       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 inline struct f_printer_opts
+*to_f_printer_opts(struct config_item *item)
+{
+       return container_of(to_config_group(item), struct f_printer_opts,
+                           func_inst.group);
+}
+
+CONFIGFS_ATTR_STRUCT(f_printer_opts);
+CONFIGFS_ATTR_OPS(f_printer_opts);
+
+static void printer_attr_release(struct config_item *item)
+{
+       struct f_printer_opts *opts = to_f_printer_opts(item);
+
+       usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations printer_item_ops = {
+       .release        = printer_attr_release,
+       .show_attribute = f_printer_opts_attr_show,
+       .store_attribute = f_printer_opts_attr_store,
+};
+
+static ssize_t f_printer_opts_pnp_string_show(struct f_printer_opts *opts,
+                                             char *page)
+{
+       int result;
+
+       mutex_lock(&opts->lock);
+       result = strlcpy(page, opts->pnp_string + 2, PNP_STRING_LEN - 2);
+       mutex_unlock(&opts->lock);
+
+       return result;
+}
+
+static ssize_t f_printer_opts_pnp_string_store(struct f_printer_opts *opts,
+                                              const char *page, size_t len)
+{
+       int result, l;
+
+       mutex_lock(&opts->lock);
+       result = strlcpy(opts->pnp_string + 2, page, PNP_STRING_LEN - 2);
+       l = strlen(opts->pnp_string + 2) + 2;
+       opts->pnp_string[0] = (l >> 8) & 0xFF;
+       opts->pnp_string[1] = l & 0xFF;
+       mutex_unlock(&opts->lock);
+
+       return result;
+}
+
+static struct f_printer_opts_attribute f_printer_opts_pnp_string =
+       __CONFIGFS_ATTR(pnp_string, S_IRUGO | S_IWUSR,
+                       f_printer_opts_pnp_string_show,
+                       f_printer_opts_pnp_string_store);
+
+static ssize_t f_printer_opts_q_len_show(struct f_printer_opts *opts,
+                                        char *page)
+{
+       int result;
+
+       mutex_lock(&opts->lock);
+       result = sprintf(page, "%d\n", opts->q_len);
+       mutex_unlock(&opts->lock);
+
+       return result;
+}
+
+static ssize_t f_printer_opts_q_len_store(struct f_printer_opts *opts,
+                                         const char *page, size_t len)
+{
+       int ret;
+       u16 num;
+
+       mutex_lock(&opts->lock);
+       if (opts->refcnt) {
+               ret = -EBUSY;
+               goto end;
+       }
+
+       ret = kstrtou16(page, 0, &num);
+       if (ret)
+               goto end;
+
+       opts->q_len = (unsigned)num;
+       ret = len;
+end:
+       mutex_unlock(&opts->lock);
+       return ret;
+}
+
+static struct f_printer_opts_attribute f_printer_opts_q_len =
+       __CONFIGFS_ATTR(q_len, S_IRUGO | S_IWUSR, f_printer_opts_q_len_show,
+                       f_printer_opts_q_len_store);
+
+static struct configfs_attribute *printer_attrs[] = {
+       &f_printer_opts_pnp_string.attr,
+       &f_printer_opts_q_len.attr,
+       NULL,
+};
+
+static struct config_item_type printer_func_type = {
+       .ct_item_ops    = &printer_item_ops,
+       .ct_attrs       = printer_attrs,
+       .ct_owner       = THIS_MODULE,
+};
+
+static inline int gprinter_get_minor(void)
+{
+       return ida_simple_get(&printer_ida, 0, 0, GFP_KERNEL);
+}
+
+static inline void gprinter_put_minor(int minor)
+{
+       ida_simple_remove(&printer_ida, minor);
+}
+
+static int gprinter_setup(int);
+static void gprinter_cleanup(void);
+
+static void gprinter_free_inst(struct usb_function_instance *f)
+{
+       struct f_printer_opts *opts;
+
+       opts = container_of(f, struct f_printer_opts, func_inst);
+
+       mutex_lock(&printer_ida_lock);
+
+       gprinter_put_minor(opts->minor);
+       if (idr_is_empty(&printer_ida.idr))
+               gprinter_cleanup();
+
+       mutex_unlock(&printer_ida_lock);
+
+       kfree(opts);
+}
+
+static struct usb_function_instance *gprinter_alloc_inst(void)
+{
+       struct f_printer_opts *opts;
+       struct usb_function_instance *ret;
+       int status = 0;
+
+       opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+       if (!opts)
+               return ERR_PTR(-ENOMEM);
+
+       mutex_init(&opts->lock);
+       opts->func_inst.free_func_inst = gprinter_free_inst;
+       ret = &opts->func_inst;
+
+       mutex_lock(&printer_ida_lock);
+
+       if (idr_is_empty(&printer_ida.idr)) {
+               status = gprinter_setup(PRINTER_MINORS);
+               if (status) {
+                       ret = ERR_PTR(status);
+                       kfree(opts);
+                       goto unlock;
+               }
+       }
+
+       opts->minor = gprinter_get_minor();
+       if (opts->minor < 0) {
+               ret = ERR_PTR(opts->minor);
+               kfree(opts);
+               if (idr_is_empty(&printer_ida.idr))
+                       gprinter_cleanup();
+               goto unlock;
+       }
+       config_group_init_type_name(&opts->func_inst.group, "",
+                                   &printer_func_type);
+
+unlock:
+       mutex_unlock(&printer_ida_lock);
+       return ret;
+}
+
+static void gprinter_free(struct usb_function *f)
+{
+       struct printer_dev *dev = func_to_printer(f);
+       struct f_printer_opts *opts;
+
+       opts = container_of(f->fi, struct f_printer_opts, func_inst);
+       kfree(dev);
+       mutex_lock(&opts->lock);
+       --opts->refcnt;
+       mutex_unlock(&opts->lock);
+}
+
+static void printer_func_unbind(struct usb_configuration *c,
+               struct usb_function *f)
+{
+       struct printer_dev      *dev;
+       struct usb_request      *req;
+
+       dev = func_to_printer(f);
+
+       device_destroy(usb_gadget_class, MKDEV(major, dev->minor));
+
+       /* 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);
+       }
+       usb_free_all_descriptors(f);
+}
+
+static struct usb_function *gprinter_alloc(struct usb_function_instance *fi)
+{
+       struct printer_dev      *dev;
+       struct f_printer_opts   *opts;
+
+       opts = container_of(fi, struct f_printer_opts, func_inst);
+
+       mutex_lock(&opts->lock);
+       if (opts->minor >= minors) {
+               mutex_unlock(&opts->lock);
+               return ERR_PTR(-ENOENT);
+       }
+
+       dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+       if (!dev) {
+               mutex_unlock(&opts->lock);
+               return ERR_PTR(-ENOMEM);
+       }
+
+       ++opts->refcnt;
+       dev->minor = opts->minor;
+       dev->pnp_string = opts->pnp_string;
+       dev->q_len = opts->q_len;
+       mutex_unlock(&opts->lock);
+
+       dev->function.name = "printer";
+       dev->function.bind = printer_func_bind;
+       dev->function.setup = printer_func_setup;
+       dev->function.unbind = printer_func_unbind;
+       dev->function.set_alt = printer_func_set_alt;
+       dev->function.disable = printer_func_disable;
+       dev->function.req_match = gprinter_req_match;
+       dev->function.free_func = gprinter_free;
+
+       INIT_LIST_HEAD(&dev->tx_reqs);
+       INIT_LIST_HEAD(&dev->rx_reqs);
+       INIT_LIST_HEAD(&dev->rx_buffers);
+       INIT_LIST_HEAD(&dev->tx_reqs_active);
+       INIT_LIST_HEAD(&dev->rx_reqs_active);
+
+       spin_lock_init(&dev->lock);
+       mutex_init(&dev->lock_printer_io);
+       init_waitqueue_head(&dev->rx_wait);
+       init_waitqueue_head(&dev->tx_wait);
+       init_waitqueue_head(&dev->tx_flush_wait);
+
+       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;
+
+       return &dev->function;
+}
+
+DECLARE_USB_FUNCTION_INIT(printer, gprinter_alloc_inst, gprinter_alloc);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Craig Nadler");
+
+static int gprinter_setup(int count)
+{
+       int status;
+       dev_t devt;
+
+       usb_gadget_class = class_create(THIS_MODULE, "usb_printer_gadget");
+       if (IS_ERR(usb_gadget_class)) {
+               status = PTR_ERR(usb_gadget_class);
+               usb_gadget_class = NULL;
+               pr_err("unable to create usb_gadget class %d\n", status);
+               return status;
+       }
+
+       status = alloc_chrdev_region(&devt, 0, count, "USB printer gadget");
+       if (status) {
+               pr_err("alloc_chrdev_region %d\n", status);
+               class_destroy(usb_gadget_class);
+               usb_gadget_class = NULL;
+               return status;
+       }
+
+       major = MAJOR(devt);
+       minors = count;
+
+       return status;
+}
+
+static void gprinter_cleanup(void)
+{
+       if (major) {
+               unregister_chrdev_region(MKDEV(major, 0), minors);
+               major = minors = 0;
+       }
+       class_destroy(usb_gadget_class);
+       usb_gadget_class = NULL;
+}