USB: Add ADU support for Ontrak ADU devices

This patch adds support for Ontrak ADU USB devices.

Fixed for printk issues by Randy Dunlap <rdunlap@xenotime.net>

Signed-off-by: Steven Haigh <netwiz@crc.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 911 insertions, 0 deletions

diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
index 20539cf9394..288d301d2bf 100644
--- a/drivers/usb/misc/Kconfig
+++ b/drivers/usb/misc/Kconfig
@@ -32,6 +32,16 @@ config USB_EMI26
 	  To compile this driver as a module, choose M here: the
 	  module will be called emi26.
 
+config USB_ADUTUX
+	tristate "ADU devices from Ontrak Control Systems (EXPERIMENTAL)"
+	depends on USB && EXPERIMENTAL
+	help
+	  Say Y if you want to use an ADU device from Ontrak Control
+	  Systems.
+
+	  To compile this driver as a module, choose M here.  The module
+	  will be called adutux.
+
 config USB_AUERSWALD
 	tristate "USB Auerswald ISDN support (EXPERIMENTAL)"
 	depends on USB && EXPERIMENTAL
diff --git a/drivers/usb/misc/Makefile b/drivers/usb/misc/Makefile
index d12a84a1c0a..73fc8be0d8c 100644
--- a/drivers/usb/misc/Makefile
+++ b/drivers/usb/misc/Makefile
@@ -3,6 +3,7 @@
 # (the ones that don't fit into any other categories)
 #
 
+obj-$(CONFIG_USB_ADUTUX)	+= adutux.o
 obj-$(CONFIG_USB_AUERSWALD)	+= auerswald.o
 obj-$(CONFIG_USB_CYPRESS_CY7C63)+= cypress_cy7c63.o
 obj-$(CONFIG_USB_CYTHERM)	+= cytherm.o
diff --git a/drivers/usb/misc/adutux.c b/drivers/usb/misc/adutux.c
new file mode 100644
index 00000000000..d3963199b6e
--- /dev/null
+++ b/drivers/usb/misc/adutux.c
@@ -0,0 +1,900 @@
+/*
+ * adutux - driver for ADU devices from Ontrak Control Systems
+ * This is an experimental driver. Use at your own risk.
+ * This driver is not supported by Ontrak Control Systems.
+ *
+ * Copyright (c) 2003 John Homppi (SCO, leave this notice here)
+ *
+ * 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.
+ *
+ * derived from the Lego USB Tower driver 0.56:
+ * Copyright (c) 2003 David Glance <davidgsf@sourceforge.net>
+ *               2001 Juergen Stuber <stuber@loria.fr>
+ * that was derived from USB Skeleton driver - 0.5
+ * Copyright (c) 2001 Greg Kroah-Hartman (greg@kroah.com)
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <asm/uaccess.h>
+
+#ifdef CONFIG_USB_DEBUG
+static int debug = 5;
+#else
+static int debug = 1;
+#endif
+
+/* Use our own dbg macro */
+#undef dbg
+#define dbg(lvl, format, arg...) 					\
+do { 									\
+	if (debug >= lvl)						\
+		printk(KERN_DEBUG __FILE__ " : " format " \n", ## arg);	\
+} while (0)
+
+
+/* Version Information */
+#define DRIVER_VERSION "v0.0.13"
+#define DRIVER_AUTHOR "John Homppi"
+#define DRIVER_DESC "adutux (see www.ontrak.net)"
+
+/* Module parameters */
+module_param(debug, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Debug enabled or not");
+
+/* Define these values to match your device */
+#define ADU_VENDOR_ID 0x0a07
+#define ADU_PRODUCT_ID 0x0064
+
+/* table of devices that work with this driver */
+static struct usb_device_id device_table [] = {
+	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID) },		/* ADU100 */
+	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+20) }, 	/* ADU120 */
+	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+30) }, 	/* ADU130 */
+	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+100) },	/* ADU200 */
+	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+108) },	/* ADU208 */
+	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+118) },	/* ADU218 */
+	{ }/* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, device_table);
+
+#ifdef CONFIG_USB_DYNAMIC_MINORS
+#define ADU_MINOR_BASE	0
+#else
+#define ADU_MINOR_BASE	67
+#endif
+
+/* we can have up to this number of device plugged in at once */
+#define MAX_DEVICES	16
+
+#define COMMAND_TIMEOUT	(2*HZ)	/* 60 second timeout for a command */
+
+/* Structure to hold all of our device specific stuff */
+struct adu_device {
+	struct semaphore	sem; /* locks this structure */
+	struct usb_device*	udev; /* save off the usb device pointer */
+	struct usb_interface*	interface;
+	unsigned char		minor; /* the starting minor number for this device */
+	char			serial_number[8];
+
+	int			open_count; /* number of times this port has been opened */
+
+	char*			read_buffer_primary;
+	int			read_buffer_length;
+	char*			read_buffer_secondary;
+	int			secondary_head;
+	int			secondary_tail;
+	spinlock_t		buflock;
+
+	wait_queue_head_t	read_wait;
+	wait_queue_head_t	write_wait;
+
+	char*			interrupt_in_buffer;
+	struct usb_endpoint_descriptor* interrupt_in_endpoint;
+	struct urb*		interrupt_in_urb;
+	int			read_urb_finished;
+
+	char*			interrupt_out_buffer;
+	struct usb_endpoint_descriptor* interrupt_out_endpoint;
+	struct urb*		interrupt_out_urb;
+};
+
+/* prevent races between open() and disconnect */
+static DEFINE_MUTEX(disconnect_mutex);
+static struct usb_driver adu_driver;
+
+static void adu_debug_data(int level, const char *function, int size,
+			   const unsigned char *data)
+{
+	int i;
+
+	if (debug < level)
+		return;
+
+	printk(KERN_DEBUG __FILE__": %s - length = %d, data = ",
+	       function, size);
+	for (i = 0; i < size; ++i)
+		printk("%.2x ", data[i]);
+	printk("\n");
+}
+
+/**
+ * adu_abort_transfers
+ *      aborts transfers and frees associated data structures
+ */
+static void adu_abort_transfers(struct adu_device *dev)
+{
+	dbg(2," %s : enter", __FUNCTION__);
+
+	if (dev == NULL) {
+		dbg(1," %s : dev is null", __FUNCTION__);
+		goto exit;
+	}
+
+	if (dev->udev == NULL) {
+		dbg(1," %s : udev is null", __FUNCTION__);
+		goto exit;
+	}
+
+	dbg(2," %s : udev state %d", __FUNCTION__, dev->udev->state);
+	if (dev->udev->state == USB_STATE_NOTATTACHED) {
+		dbg(1," %s : udev is not attached", __FUNCTION__);
+		goto exit;
+	}
+
+	/* shutdown transfer */
+	usb_unlink_urb(dev->interrupt_in_urb);
+	usb_unlink_urb(dev->interrupt_out_urb);
+
+exit:
+	dbg(2," %s : leave", __FUNCTION__);
+}
+
+static void adu_delete(struct adu_device *dev)
+{
+	dbg(2, "%s enter", __FUNCTION__);
+
+	adu_abort_transfers(dev);
+
+	/* free data structures */
+	usb_free_urb(dev->interrupt_in_urb);
+	usb_free_urb(dev->interrupt_out_urb);
+	kfree(dev->read_buffer_primary);
+	kfree(dev->read_buffer_secondary);
+	kfree(dev->interrupt_in_buffer);
+	kfree(dev->interrupt_out_buffer);
+	kfree(dev);
+
+	dbg(2, "%s : leave", __FUNCTION__);
+}
+
+static void adu_interrupt_in_callback(struct urb *urb, struct pt_regs *regs)
+{
+	struct adu_device *dev = urb->context;
+
+	dbg(4," %s : enter, status %d", __FUNCTION__, urb->status);
+	adu_debug_data(5, __FUNCTION__, urb->actual_length,
+		       urb->transfer_buffer);
+
+	spin_lock(&dev->buflock);
+
+	if (urb->status != 0) {
+		if ((urb->status != -ENOENT) && (urb->status != -ECONNRESET)) {
+			dbg(1," %s : nonzero status received: %d",
+			    __FUNCTION__, urb->status);
+		}
+		goto exit;
+	}
+
+	if (urb->actual_length > 0 && dev->interrupt_in_buffer[0] != 0x00) {
+		if (dev->read_buffer_length <
+		    (4 * le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize)) -
+		     (urb->actual_length)) {
+			memcpy (dev->read_buffer_primary +
+				dev->read_buffer_length,
+				dev->interrupt_in_buffer, urb->actual_length);
+
+			dev->read_buffer_length += urb->actual_length;
+			dbg(2," %s reading  %d ", __FUNCTION__,
+			    urb->actual_length);
+		} else {
+			dbg(1," %s : read_buffer overflow", __FUNCTION__);
+		}
+	}
+
+exit:
+	dev->read_urb_finished = 1;
+	spin_unlock(&dev->buflock);
+	/* always wake up so we recover from errors */
+	wake_up_interruptible(&dev->read_wait);
+	adu_debug_data(5, __FUNCTION__, urb->actual_length,
+		       urb->transfer_buffer);
+	dbg(4," %s : leave, status %d", __FUNCTION__, urb->status);
+}
+
+static void adu_interrupt_out_callback(struct urb *urb, struct pt_regs *regs)
+{
+	struct adu_device *dev = urb->context;
+
+	dbg(4," %s : enter, status %d", __FUNCTION__, urb->status);
+	adu_debug_data(5,__FUNCTION__, urb->actual_length, urb->transfer_buffer);
+
+	if (urb->status != 0) {
+		if ((urb->status != -ENOENT) &&
+		    (urb->status != -ECONNRESET)) {
+			dbg(1, " %s :nonzero status received: %d",
+			    __FUNCTION__, urb->status);
+		}
+		goto exit;
+	}
+
+	wake_up_interruptible(&dev->write_wait);
+exit:
+
+	adu_debug_data(5, __FUNCTION__, urb->actual_length,
+		       urb->transfer_buffer);
+	dbg(4," %s : leave, status %d", __FUNCTION__, urb->status);
+}
+
+static int adu_open(struct inode *inode, struct file *file)
+{
+	struct adu_device *dev = NULL;
+	struct usb_interface *interface;
+	int subminor;
+	int retval = 0;
+
+	dbg(2,"%s : enter", __FUNCTION__);
+
+	subminor = iminor(inode);
+
+	mutex_lock(&disconnect_mutex);
+
+	interface = usb_find_interface(&adu_driver, subminor);
+	if (!interface) {
+		err("%s - error, can't find device for minor %d",
+		    __FUNCTION__, subminor);
+		retval = -ENODEV;
+		goto exit_no_device;
+	}
+
+	dev = usb_get_intfdata(interface);
+	if (!dev) {
+		retval = -ENODEV;
+		goto exit_no_device;
+	}
+
+	/* lock this device */
+	if ((retval = down_interruptible(&dev->sem))) {
+		dbg(2, "%s : sem down failed", __FUNCTION__);
+		goto exit_no_device;
+	}
+
+	/* increment our usage count for the device */
+	++dev->open_count;
+	dbg(2,"%s : open count %d", __FUNCTION__, dev->open_count);
+
+	/* save device in the file's private structure */
+	file->private_data = dev;
+
+	/* initialize in direction */
+	dev->read_buffer_length = 0;
+
+	/* fixup first read by having urb waiting for it */
+	usb_fill_int_urb(dev->interrupt_in_urb,dev->udev,
+			 usb_rcvintpipe(dev->udev,
+			 		dev->interrupt_in_endpoint->bEndpointAddress),
+			 dev->interrupt_in_buffer,
+			 le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize),
+			 adu_interrupt_in_callback, dev,
+			 dev->interrupt_in_endpoint->bInterval);
+	/* dev->interrupt_in_urb->transfer_flags |= URB_ASYNC_UNLINK; */
+	dev->read_urb_finished = 0;
+	usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
+	/* we ignore failure */
+	/* end of fixup for first read */
+
+	up(&dev->sem);
+
+exit_no_device:
+	mutex_unlock(&disconnect_mutex);
+	dbg(2,"%s : leave, return value %d ", __FUNCTION__, retval);
+
+	return retval;
+}
+
+static int adu_release_internal(struct adu_device *dev)
+{
+	int retval = 0;
+
+	dbg(2," %s : enter", __FUNCTION__);
+
+	if (dev->udev == NULL) {
+		/* the device was unplugged before the file was released */
+		adu_delete(dev);
+		goto exit;
+	}
+
+	/* decrement our usage count for the device */
+	--dev->open_count;
+	dbg(2," %s : open count %d", __FUNCTION__, dev->open_count);
+	if (dev->open_count <= 0) {
+		adu_abort_transfers(dev);
+		dev->open_count = 0;
+	}
+
+exit:
+	dbg(2," %s : leave", __FUNCTION__);
+	return retval;
+}
+
+static int adu_release(struct inode *inode, struct file *file)
+{
+	struct adu_device *dev = NULL;
+	int retval = 0;
+
+	dbg(2," %s : enter", __FUNCTION__);
+
+	if (file == NULL) {
+ 		dbg(1," %s : file is NULL", __FUNCTION__);
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	dev = file->private_data;
+
+	if (dev == NULL) {
+ 		dbg(1," %s : object is NULL", __FUNCTION__);
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	/* lock our device */
+	down(&dev->sem); /* not interruptible */
+
+	if (dev->open_count <= 0) {
+		dbg(1," %s : device not opened", __FUNCTION__);
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	/* do the work */
+	retval = adu_release_internal(dev);
+
+exit:
+	up(&dev->sem);
+	dbg(2," %s : leave, return value %d", __FUNCTION__, retval);
+	return retval;
+}
+
+static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,
+			loff_t *ppos)
+{
+	struct adu_device *dev;
+	size_t bytes_read = 0;
+	size_t bytes_to_read = count;
+	int i;
+	int retval = 0;
+	int timeout = 0;
+	int should_submit = 0;
+	unsigned long flags;
+	DECLARE_WAITQUEUE(wait, current);
+
+	dbg(2," %s : enter, count = %Zd, file=%p", __FUNCTION__, count, file);
+
+	dev = file->private_data;
+	dbg(2," %s : dev=%p", __FUNCTION__, dev);
+	/* lock this object */
+	if (down_interruptible(&dev->sem))
+		return -ERESTARTSYS;
+
+	/* verify that the device wasn't unplugged */
+	if (dev->udev == NULL || dev->minor == 0) {
+		retval = -ENODEV;
+		err("No device or device unplugged %d", retval);
+		goto exit;
+	}
+
+	/* verify that some data was requested */
+	if (count == 0) {
+		dbg(1," %s : read request of 0 bytes", __FUNCTION__);
+		goto exit;
+	}
+
+	timeout = COMMAND_TIMEOUT;
+	dbg(2," %s : about to start looping", __FUNCTION__);
+	while (bytes_to_read) {
+		int data_in_secondary = dev->secondary_tail - dev->secondary_head;
+		dbg(2," %s : while, data_in_secondary=%d, status=%d",
+		    __FUNCTION__, data_in_secondary,
+		    dev->interrupt_in_urb->status);
+
+		if (data_in_secondary) {
+			/* drain secondary buffer */
+			int amount = bytes_to_read < data_in_secondary ? bytes_to_read : data_in_secondary;
+			i = copy_to_user(buffer, dev->read_buffer_secondary+dev->secondary_head, amount);
+			if (i < 0) {
+				retval = -EFAULT;
+				goto exit;
+			}
+			dev->secondary_head += (amount - i);
+			bytes_read += (amount - i);
+			bytes_to_read -= (amount - i);
+			if (i) {
+				retval = bytes_read ? bytes_read : -EFAULT;
+				goto exit;
+			}
+		} else {
+			/* we check the primary buffer */
+			spin_lock_irqsave (&dev->buflock, flags);
+			if (dev->read_buffer_length) {
+				/* we secure access to the primary */
+				char *tmp;
+				dbg(2," %s : swap, read_buffer_length = %d",
+				    __FUNCTION__, dev->read_buffer_length);
+				tmp = dev->read_buffer_secondary;
+				dev->read_buffer_secondary = dev->read_buffer_primary;
+				dev->read_buffer_primary = tmp;
+				dev->secondary_head = 0;
+				dev->secondary_tail = dev->read_buffer_length;
+				dev->read_buffer_length = 0;
+				spin_unlock_irqrestore(&dev->buflock, flags);
+				/* we have a free buffer so use it */
+				should_submit = 1;
+			} else {
+				/* even the primary was empty - we may need to do IO */
+				if (dev->interrupt_in_urb->status == -EINPROGRESS) {
+					/* somebody is doing IO */
+					spin_unlock_irqrestore(&dev->buflock, flags);
+					dbg(2," %s : submitted already", __FUNCTION__);
+				} else {
+					/* we must initiate input */
+					dbg(2," %s : initiate input", __FUNCTION__);
+					dev->read_urb_finished = 0;
+
+					usb_fill_int_urb(dev->interrupt_in_urb,dev->udev,
+							 usb_rcvintpipe(dev->udev,
+							 		dev->interrupt_in_endpoint->bEndpointAddress),
+							 dev->interrupt_in_buffer,
+							 le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize),
+							 adu_interrupt_in_callback,
+							 dev,
+							 dev->interrupt_in_endpoint->bInterval);
+					retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
+					if (!retval) {
+						spin_unlock_irqrestore(&dev->buflock, flags);
+						dbg(2," %s : submitted OK", __FUNCTION__);
+					} else {
+						if (retval == -ENOMEM) {
+							retval = bytes_read ? bytes_read : -ENOMEM;
+						}
+						spin_unlock_irqrestore(&dev->buflock, flags);
+						dbg(2," %s : submit failed", __FUNCTION__);
+						goto exit;
+					}
+				}
+
+				/* we wait for I/O to complete */
+				set_current_state(TASK_INTERRUPTIBLE);
+				add_wait_queue(&dev->read_wait, &wait);
+				if (!dev->read_urb_finished)
+					timeout = schedule_timeout(COMMAND_TIMEOUT);
+				else
+					set_current_state(TASK_RUNNING);
+				remove_wait_queue(&dev->read_wait, &wait);
+
+				if (timeout <= 0) {
+					dbg(2," %s : timeout", __FUNCTION__);
+					retval = bytes_read ? bytes_read : -ETIMEDOUT;
+					goto exit;
+				}
+
+				if (signal_pending(current)) {
+					dbg(2," %s : signal pending", __FUNCTION__);
+					retval = bytes_read ? bytes_read : -EINTR;
+					goto exit;
+				}
+			}
+		}
+	}
+
+	retval = bytes_read;
+	/* if the primary buffer is empty then use it */
+	if (should_submit && !dev->interrupt_in_urb->status==-EINPROGRESS) {
+		usb_fill_int_urb(dev->interrupt_in_urb,dev->udev,
+				 usb_rcvintpipe(dev->udev,
+				 		dev->interrupt_in_endpoint->bEndpointAddress),
+						dev->interrupt_in_buffer,
+						le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize),
+						adu_interrupt_in_callback,
+						dev,
+						dev->interrupt_in_endpoint->bInterval);
+		/* dev->interrupt_in_urb->transfer_flags |= URB_ASYNC_UNLINK; */
+		dev->read_urb_finished = 0;
+		usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
+		/* we ignore failure */
+	}
+
+exit:
+	/* unlock the device */
+	up(&dev->sem);
+
+	dbg(2," %s : leave, return value %d", __FUNCTION__, retval);
+	return retval;
+}
+
+static ssize_t adu_write(struct file *file, const __user char *buffer,
+			 size_t count, loff_t *ppos)
+{
+	struct adu_device *dev;
+	size_t bytes_written = 0;
+	size_t bytes_to_write;
+	size_t buffer_size;
+	int retval = 0;
+	int timeout = 0;
+
+	dbg(2," %s : enter, count = %Zd", __FUNCTION__, count);
+
+	dev = file->private_data;
+
+	/* lock this object */
+	down_interruptible(&dev->sem);
+
+	/* verify that the device wasn't unplugged */
+	if (dev->udev == NULL || dev->minor == 0) {
+		retval = -ENODEV;
+		err("No device or device unplugged %d", retval);
+		goto exit;
+	}
+
+	/* verify that we actually have some data to write */
+	if (count == 0) {
+		dbg(1," %s : write request of 0 bytes", __FUNCTION__);
+		goto exit;
+	}
+
+
+	while (count > 0) {
+		if (dev->interrupt_out_urb->status == -EINPROGRESS) {
+			timeout = COMMAND_TIMEOUT;
+
+			while (timeout > 0) {
+				if (signal_pending(current)) {
+				dbg(1," %s : interrupted", __FUNCTION__);
+				retval = -EINTR;
+				goto exit;
+			}
+			up(&dev->sem);
+			timeout = interruptible_sleep_on_timeout(&dev->write_wait, timeout);
+			down_interruptible(&dev->sem);
+			if (timeout > 0) {
+				break;
+			}
+			dbg(1," %s : interrupted timeout: %d", __FUNCTION__, timeout);
+		}
+
+
+		dbg(1," %s : final timeout: %d", __FUNCTION__, timeout);
+
+		if (timeout == 0) {
+			dbg(1, "%s - command timed out.", __FUNCTION__);
+			retval = -ETIMEDOUT;
+			goto exit;
+		}
+
+		dbg(4," %s : in progress, count = %Zd", __FUNCTION__, count);
+
+		} else {
+			dbg(4," %s : sending, count = %Zd", __FUNCTION__, count);
+
+			/* write the data into interrupt_out_buffer from userspace */
+			buffer_size = le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize);
+			bytes_to_write = count > buffer_size ? buffer_size : count;
+			dbg(4," %s : buffer_size = %Zd, count = %Zd, bytes_to_write = %Zd",
+			    __FUNCTION__, buffer_size, count, bytes_to_write);
+
+			if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write) != 0) {
+				retval = -EFAULT;
+				goto exit;
+			}
+
+			/* send off the urb */
+			usb_fill_int_urb(
+				dev->interrupt_out_urb,
+				dev->udev,
+				usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
+				dev->interrupt_out_buffer,
+				bytes_to_write,
+				adu_interrupt_out_callback,
+				dev,
+				dev->interrupt_in_endpoint->bInterval);
+			/* dev->interrupt_in_urb->transfer_flags |= URB_ASYNC_UNLINK; */
+			dev->interrupt_out_urb->actual_length = bytes_to_write;
+			retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
+			if (retval < 0) {
+				err("Couldn't submit interrupt_out_urb %d", retval);
+				goto exit;
+			}
+
+			buffer += bytes_to_write;
+			count -= bytes_to_write;
+
+			bytes_written += bytes_to_write;
+		}
+	}
+
+	retval = bytes_written;
+
+exit:
+	/* unlock the device */
+	up(&dev->sem);
+
+	dbg(2," %s : leave, return value %d", __FUNCTION__, retval);
+
+	return retval;
+}
+
+/* file operations needed when we register this driver */
+static struct file_operations adu_fops = {
+	.owner = THIS_MODULE,
+	.read  = adu_read,
+	.write = adu_write,
+	.open = adu_open,
+	.release = adu_release,
+};
+
+/*
+ * usb class driver info in order to get a minor number from the usb core,
+ * and to have the device registered with devfs and the driver core
+ */
+static struct usb_class_driver adu_class = {
+	.name = "usb/adutux%d",
+	.fops = &adu_fops,
+	.minor_base = ADU_MINOR_BASE,
+};
+
+/**
+ * adu_probe
+ *
+ * Called by the usb core when a new device is connected that it thinks
+ * this driver might be interested in.
+ */
+static int adu_probe(struct usb_interface *interface,
+		     const struct usb_device_id *id)
+{
+	struct usb_device *udev = interface_to_usbdev(interface);
+	struct adu_device *dev = NULL;
+	struct usb_host_interface *iface_desc;
+	struct usb_endpoint_descriptor *endpoint;
+	int retval = -ENODEV;
+	int in_end_size;
+	int out_end_size;
+	int i;
+
+	dbg(2," %s : enter", __FUNCTION__);
+
+	if (udev == NULL) {
+		dev_err(&interface->dev, "udev is NULL.\n");
+		goto exit;
+	}
+
+	/* allocate memory for our device state and intialize it */
+	dev = kzalloc(sizeof(struct adu_device), GFP_KERNEL);
+	if (dev == NULL) {
+		dev_err(&interface->dev, "Out of memory\n");
+		retval = -ENOMEM;
+		goto exit;
+	}
+
+	init_MUTEX(&dev->sem);
+	spin_lock_init(&dev->buflock);
+	dev->udev = udev;
+	init_waitqueue_head(&dev->read_wait);
+	init_waitqueue_head(&dev->write_wait);
+
+	iface_desc = &interface->altsetting[0];
+
+	/* set up the endpoint information */
+	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
+		endpoint = &iface_desc->endpoint[i].desc;
+
+		if (usb_endpoint_is_int_in(endpoint))
+			dev->interrupt_in_endpoint = endpoint;
+
+		if (usb_endpoint_is_int_out(endpoint))
+			dev->interrupt_out_endpoint = endpoint;
+	}
+	if (dev->interrupt_in_endpoint == NULL) {
+		dev_err(&interface->dev, "interrupt in endpoint not found\n");
+		goto error;
+	}
+	if (dev->interrupt_out_endpoint == NULL) {
+		dev_err(&interface->dev, "interrupt out endpoint not found\n");
+		goto error;
+	}
+
+	in_end_size = le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
+	out_end_size = le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize);
+
+	dev->read_buffer_primary = kmalloc((4 * in_end_size), GFP_KERNEL);
+	if (!dev->read_buffer_primary) {
+		dev_err(&interface->dev, "Couldn't allocate read_buffer_primary\n");
+		retval = -ENOMEM;
+		goto error;
+	}
+
+	/* debug code prime the buffer */
+	memset(dev->read_buffer_primary, 'a', in_end_size);
+	memset(dev->read_buffer_primary + in_end_size, 'b', in_end_size);
+	memset(dev->read_buffer_primary + (2 * in_end_size), 'c', in_end_size);
+	memset(dev->read_buffer_primary + (3 * in_end_size), 'd', in_end_size);
+
+	dev->read_buffer_secondary = kmalloc((4 * in_end_size), GFP_KERNEL);
+	if (!dev->read_buffer_secondary) {
+		dev_err(&interface->dev, "Couldn't allocate read_buffer_secondary\n");
+		retval = -ENOMEM;
+		goto error;
+	}
+
+	/* debug code prime the buffer */
+	memset(dev->read_buffer_secondary, 'e', in_end_size);
+	memset(dev->read_buffer_secondary + in_end_size, 'f', in_end_size);
+	memset(dev->read_buffer_secondary + (2 * in_end_size), 'g', in_end_size);
+	memset(dev->read_buffer_secondary + (3 * in_end_size), 'h', in_end_size);
+
+	dev->interrupt_in_buffer = kmalloc(in_end_size, GFP_KERNEL);
+	if (!dev->interrupt_in_buffer) {
+		dev_err(&interface->dev, "Couldn't allocate interrupt_in_buffer\n");
+		goto error;
+	}
+
+	/* debug code prime the buffer */
+	memset(dev->interrupt_in_buffer, 'i', in_end_size);
+
+	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!dev->interrupt_in_urb) {
+		dev_err(&interface->dev, "Couldn't allocate interrupt_in_urb\n");
+		goto error;
+	}
+	dev->interrupt_out_buffer = kmalloc(out_end_size, GFP_KERNEL);
+	if (!dev->interrupt_out_buffer) {
+		dev_err(&interface->dev, "Couldn't allocate interrupt_out_buffer\n");
+		goto error;
+	}
+	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!dev->interrupt_out_urb) {
+		dev_err(&interface->dev, "Couldn't allocate interrupt_out_urb\n");
+		goto error;
+	}
+
+	if (!usb_string(udev, udev->descriptor.iSerialNumber, dev->serial_number,
+			sizeof(dev->serial_number))) {
+		dev_err(&interface->dev, "Could not retrieve serial number\n");
+		goto error;
+	}
+	dbg(2," %s : serial_number=%s", __FUNCTION__, dev->serial_number);
+
+	/* we can register the device now, as it is ready */
+	usb_set_intfdata(interface, dev);
+
+	retval = usb_register_dev(interface, &adu_class);
+
+	if (retval) {
+		/* something prevented us from registering this driver */
+		dev_err(&interface->dev, "Not able to get a minor for this device.\n");
+		usb_set_intfdata(interface, NULL);
+		goto error;
+	}
+
+	dev->minor = interface->minor;
+
+	/* let the user know what node this device is now attached to */
+	dev_info(&interface->dev, "ADU%d %s now attached to /dev/usb/adutux%d",
+		 udev->descriptor.idProduct, dev->serial_number,
+		 (dev->minor - ADU_MINOR_BASE));
+exit:
+	dbg(2," %s : leave, return value %p (dev)", __FUNCTION__, dev);
+
+	return retval;
+
+error:
+	adu_delete(dev);
+	return retval;
+}
+
+/**
+ * adu_disconnect
+ *
+ * Called by the usb core when the device is removed from the system.
+ */
+static void adu_disconnect(struct usb_interface *interface)
+{
+	struct adu_device *dev;
+	int minor;
+
+	dbg(2," %s : enter", __FUNCTION__);
+
+	mutex_lock(&disconnect_mutex); /* not interruptible */
+
+	dev = usb_get_intfdata(interface);
+	usb_set_intfdata(interface, NULL);
+
+	down(&dev->sem); /* not interruptible */
+
+	minor = dev->minor;
+
+	/* give back our minor */
+	usb_deregister_dev(interface, &adu_class);
+	dev->minor = 0;
+
+	/* if the device is not opened, then we clean up right now */
+	dbg(2," %s : open count %d", __FUNCTION__, dev->open_count);
+	if (!dev->open_count) {
+		up(&dev->sem);
+		adu_delete(dev);
+	} else {
+		dev->udev = NULL;
+		up(&dev->sem);
+	}
+
+	mutex_unlock(&disconnect_mutex);
+
+	dev_info(&interface->dev, "ADU device adutux%d now disconnected",
+		 (minor - ADU_MINOR_BASE));
+
+	dbg(2," %s : leave", __FUNCTION__);
+}
+
+/* usb specific object needed to register this driver with the usb subsystem */
+static struct usb_driver adu_driver = {
+	.name = "adutux",
+	.probe = adu_probe,
+	.disconnect = adu_disconnect,
+	.id_table = device_table,
+};
+
+static int __init adu_init(void)
+{
+	int result;
+
+	dbg(2," %s : enter", __FUNCTION__);
+
+	/* register this driver with the USB subsystem */
+	result = usb_register(&adu_driver);
+	if (result < 0) {
+		err("usb_register failed for the "__FILE__" driver. "
+		    "Error number %d", result);
+		goto exit;
+	}
+
+	info("adutux " DRIVER_DESC " " DRIVER_VERSION);
+	info("adutux is an experimental driver. Use at your own risk");
+
+exit:
+	dbg(2," %s : leave, return value %d", __FUNCTION__, result);
+
+	return result;
+}
+
+static void __exit adu_exit(void)
+{
+	dbg(2," %s : enter", __FUNCTION__);
+	/* deregister this driver with the USB subsystem */
+	usb_deregister(&adu_driver);
+	dbg(2," %s : leave", __FUNCTION__);
+}
+
+module_init(adu_init);
+module_exit(adu_exit);
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");