Add the rt linux 4.1.3-rt3 as base

Import the rt linux 4.1.3-rt3 as OPNFV kvm base.

It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:

commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Sat Jul 25 12:13:34 2015 +0200

    Prepare v4.1.3-rt3

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.

Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>

1 files changed, 816 insertions, 0 deletions

diff --git a/kernel/drivers/usb/misc/ldusb.c b/kernel/drivers/usb/misc/ldusb.c
new file mode 100644
index 000000000..82503a7ff
--- /dev/null
+++ b/kernel/drivers/usb/misc/ldusb.c
@@ -0,0 +1,816 @@
+/**
+ * Generic USB driver for report based interrupt in/out devices
+ * like LD Didactic's USB devices. LD Didactic's USB devices are
+ * HID devices which do not use HID report definitons (they use
+ * raw interrupt in and our reports only for communication).
+ *
+ * This driver uses a ring buffer for time critical reading of
+ * interrupt in reports and provides read and write methods for
+ * raw interrupt reports (similar to the Windows HID driver).
+ * Devices based on the book USB COMPLETE by Jan Axelson may need
+ * such a compatibility to the Windows HID driver.
+ *
+ * Copyright (C) 2005 Michael Hund <mhund@ld-didactic.de>
+ *
+ *	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 Lego USB Tower driver
+ * Copyright (C) 2003 David Glance <advidgsf@sourceforge.net>
+ *		 2001-2004 Juergen Stuber <starblue@users.sourceforge.net>
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+
+#include <asm/uaccess.h>
+#include <linux/input.h>
+#include <linux/usb.h>
+#include <linux/poll.h>
+
+/* Define these values to match your devices */
+#define USB_VENDOR_ID_LD		0x0f11	/* USB Vendor ID of LD Didactic GmbH */
+#define USB_DEVICE_ID_LD_CASSY		0x1000	/* USB Product ID of CASSY-S modules with 8 bytes endpoint size */
+#define USB_DEVICE_ID_LD_CASSY2		0x1001	/* USB Product ID of CASSY-S modules with 64 bytes endpoint size */
+#define USB_DEVICE_ID_LD_POCKETCASSY	0x1010	/* USB Product ID of Pocket-CASSY */
+#define USB_DEVICE_ID_LD_POCKETCASSY2	0x1011	/* USB Product ID of Pocket-CASSY 2 (reserved) */
+#define USB_DEVICE_ID_LD_MOBILECASSY	0x1020	/* USB Product ID of Mobile-CASSY */
+#define USB_DEVICE_ID_LD_MOBILECASSY2	0x1021	/* USB Product ID of Mobile-CASSY 2 (reserved) */
+#define USB_DEVICE_ID_LD_MICROCASSYVOLTAGE	0x1031	/* USB Product ID of Micro-CASSY Voltage */
+#define USB_DEVICE_ID_LD_MICROCASSYCURRENT	0x1032	/* USB Product ID of Micro-CASSY Current */
+#define USB_DEVICE_ID_LD_MICROCASSYTIME		0x1033	/* USB Product ID of Micro-CASSY Time (reserved) */
+#define USB_DEVICE_ID_LD_MICROCASSYTEMPERATURE	0x1035	/* USB Product ID of Micro-CASSY Temperature */
+#define USB_DEVICE_ID_LD_MICROCASSYPH		0x1038	/* USB Product ID of Micro-CASSY pH */
+#define USB_DEVICE_ID_LD_JWM		0x1080	/* USB Product ID of Joule and Wattmeter */
+#define USB_DEVICE_ID_LD_DMMP		0x1081	/* USB Product ID of Digital Multimeter P (reserved) */
+#define USB_DEVICE_ID_LD_UMIP		0x1090	/* USB Product ID of UMI P */
+#define USB_DEVICE_ID_LD_UMIC		0x10A0	/* USB Product ID of UMI C */
+#define USB_DEVICE_ID_LD_UMIB		0x10B0	/* USB Product ID of UMI B */
+#define USB_DEVICE_ID_LD_XRAY		0x1100	/* USB Product ID of X-Ray Apparatus 55481 */
+#define USB_DEVICE_ID_LD_XRAY2		0x1101	/* USB Product ID of X-Ray Apparatus 554800 */
+#define USB_DEVICE_ID_LD_XRAYCT		0x1110	/* USB Product ID of X-Ray Apparatus CT 554821*/
+#define USB_DEVICE_ID_LD_VIDEOCOM	0x1200	/* USB Product ID of VideoCom */
+#define USB_DEVICE_ID_LD_MOTOR		0x1210	/* USB Product ID of Motor (reserved) */
+#define USB_DEVICE_ID_LD_COM3LAB	0x2000	/* USB Product ID of COM3LAB */
+#define USB_DEVICE_ID_LD_TELEPORT	0x2010	/* USB Product ID of Terminal Adapter */
+#define USB_DEVICE_ID_LD_NETWORKANALYSER 0x2020	/* USB Product ID of Network Analyser */
+#define USB_DEVICE_ID_LD_POWERCONTROL	0x2030	/* USB Product ID of Converter Control Unit */
+#define USB_DEVICE_ID_LD_MACHINETEST	0x2040	/* USB Product ID of Machine Test System */
+#define USB_DEVICE_ID_LD_MOSTANALYSER	0x2050	/* USB Product ID of MOST Protocol Analyser */
+#define USB_DEVICE_ID_LD_MOSTANALYSER2	0x2051	/* USB Product ID of MOST Protocol Analyser 2 */
+#define USB_DEVICE_ID_LD_ABSESP		0x2060	/* USB Product ID of ABS ESP */
+#define USB_DEVICE_ID_LD_AUTODATABUS	0x2070	/* USB Product ID of Automotive Data Buses */
+#define USB_DEVICE_ID_LD_MCT		0x2080	/* USB Product ID of Microcontroller technique */
+#define USB_DEVICE_ID_LD_HYBRID		0x2090	/* USB Product ID of Automotive Hybrid */
+#define USB_DEVICE_ID_LD_HEATCONTROL	0x20A0	/* USB Product ID of Heat control */
+
+#define USB_VENDOR_ID_VERNIER		0x08f7
+#define USB_DEVICE_ID_VERNIER_GOTEMP	0x0002
+#define USB_DEVICE_ID_VERNIER_SKIP	0x0003
+#define USB_DEVICE_ID_VERNIER_CYCLOPS	0x0004
+#define USB_DEVICE_ID_VERNIER_LCSPEC	0x0006
+
+#ifdef CONFIG_USB_DYNAMIC_MINORS
+#define USB_LD_MINOR_BASE	0
+#else
+#define USB_LD_MINOR_BASE	176
+#endif
+
+/* table of devices that work with this driver */
+static const struct usb_device_id ld_usb_table[] = {
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_CASSY) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_CASSY2) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POCKETCASSY) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POCKETCASSY2) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOBILECASSY) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOBILECASSY2) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYVOLTAGE) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYCURRENT) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYTIME) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYTEMPERATURE) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYPH) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_JWM) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_DMMP) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_UMIP) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_UMIC) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_UMIB) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_XRAY) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_XRAY2) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_VIDEOCOM) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOTOR) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_COM3LAB) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_TELEPORT) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_NETWORKANALYSER) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POWERCONTROL) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MACHINETEST) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOSTANALYSER) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOSTANALYSER2) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_ABSESP) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_AUTODATABUS) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MCT) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_HYBRID) },
+	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_HEATCONTROL) },
+	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_GOTEMP) },
+	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_SKIP) },
+	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_CYCLOPS) },
+	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_LCSPEC) },
+	{ }					/* Terminating entry */
+};
+MODULE_DEVICE_TABLE(usb, ld_usb_table);
+MODULE_VERSION("V0.14");
+MODULE_AUTHOR("Michael Hund <mhund@ld-didactic.de>");
+MODULE_DESCRIPTION("LD USB Driver");
+MODULE_LICENSE("GPL");
+MODULE_SUPPORTED_DEVICE("LD USB Devices");
+
+/* All interrupt in transfers are collected in a ring buffer to
+ * avoid racing conditions and get better performance of the driver.
+ */
+static int ring_buffer_size = 128;
+module_param(ring_buffer_size, int, 0);
+MODULE_PARM_DESC(ring_buffer_size, "Read ring buffer size in reports");
+
+/* The write_buffer can contain more than one interrupt out transfer.
+ */
+static int write_buffer_size = 10;
+module_param(write_buffer_size, int, 0);
+MODULE_PARM_DESC(write_buffer_size, "Write buffer size in reports");
+
+/* As of kernel version 2.6.4 ehci-hcd uses an
+ * "only one interrupt transfer per frame" shortcut
+ * to simplify the scheduling of periodic transfers.
+ * This conflicts with our standard 1ms intervals for in and out URBs.
+ * We use default intervals of 2ms for in and 2ms for out transfers,
+ * which should be fast enough.
+ * Increase the interval to allow more devices that do interrupt transfers,
+ * or set to 1 to use the standard interval from the endpoint descriptors.
+ */
+static int min_interrupt_in_interval = 2;
+module_param(min_interrupt_in_interval, int, 0);
+MODULE_PARM_DESC(min_interrupt_in_interval, "Minimum interrupt in interval in ms");
+
+static int min_interrupt_out_interval = 2;
+module_param(min_interrupt_out_interval, int, 0);
+MODULE_PARM_DESC(min_interrupt_out_interval, "Minimum interrupt out interval in ms");
+
+/* Structure to hold all of our device specific stuff */
+struct ld_usb {
+	struct mutex		mutex;		/* locks this structure */
+	struct usb_interface*	intf;		/* save off the usb interface pointer */
+
+	int			open_count;	/* number of times this port has been opened */
+
+	char*			ring_buffer;
+	unsigned int		ring_head;
+	unsigned int		ring_tail;
+
+	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			interrupt_in_interval;
+	size_t			interrupt_in_endpoint_size;
+	int			interrupt_in_running;
+	int			interrupt_in_done;
+	int			buffer_overflow;
+	spinlock_t		rbsl;
+
+	char*			interrupt_out_buffer;
+	struct usb_endpoint_descriptor* interrupt_out_endpoint;
+	struct urb*		interrupt_out_urb;
+	int			interrupt_out_interval;
+	size_t			interrupt_out_endpoint_size;
+	int			interrupt_out_busy;
+};
+
+static struct usb_driver ld_usb_driver;
+
+/**
+ *	ld_usb_abort_transfers
+ *      aborts transfers and frees associated data structures
+ */
+static void ld_usb_abort_transfers(struct ld_usb *dev)
+{
+	/* shutdown transfer */
+	if (dev->interrupt_in_running) {
+		dev->interrupt_in_running = 0;
+		if (dev->intf)
+			usb_kill_urb(dev->interrupt_in_urb);
+	}
+	if (dev->interrupt_out_busy)
+		if (dev->intf)
+			usb_kill_urb(dev->interrupt_out_urb);
+}
+
+/**
+ *	ld_usb_delete
+ */
+static void ld_usb_delete(struct ld_usb *dev)
+{
+	ld_usb_abort_transfers(dev);
+
+	/* free data structures */
+	usb_free_urb(dev->interrupt_in_urb);
+	usb_free_urb(dev->interrupt_out_urb);
+	kfree(dev->ring_buffer);
+	kfree(dev->interrupt_in_buffer);
+	kfree(dev->interrupt_out_buffer);
+	kfree(dev);
+}
+
+/**
+ *	ld_usb_interrupt_in_callback
+ */
+static void ld_usb_interrupt_in_callback(struct urb *urb)
+{
+	struct ld_usb *dev = urb->context;
+	size_t *actual_buffer;
+	unsigned int next_ring_head;
+	int status = urb->status;
+	int retval;
+
+	if (status) {
+		if (status == -ENOENT ||
+		    status == -ECONNRESET ||
+		    status == -ESHUTDOWN) {
+			goto exit;
+		} else {
+			dev_dbg(&dev->intf->dev,
+				"%s: nonzero status received: %d\n", __func__,
+				status);
+			spin_lock(&dev->rbsl);
+			goto resubmit; /* maybe we can recover */
+		}
+	}
+
+	spin_lock(&dev->rbsl);
+	if (urb->actual_length > 0) {
+		next_ring_head = (dev->ring_head+1) % ring_buffer_size;
+		if (next_ring_head != dev->ring_tail) {
+			actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_head*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
+			/* actual_buffer gets urb->actual_length + interrupt_in_buffer */
+			*actual_buffer = urb->actual_length;
+			memcpy(actual_buffer+1, dev->interrupt_in_buffer, urb->actual_length);
+			dev->ring_head = next_ring_head;
+			dev_dbg(&dev->intf->dev, "%s: received %d bytes\n",
+				__func__, urb->actual_length);
+		} else {
+			dev_warn(&dev->intf->dev,
+				 "Ring buffer overflow, %d bytes dropped\n",
+				 urb->actual_length);
+			dev->buffer_overflow = 1;
+		}
+	}
+
+resubmit:
+	/* resubmit if we're still running */
+	if (dev->interrupt_in_running && !dev->buffer_overflow && dev->intf) {
+		retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
+		if (retval) {
+			dev_err(&dev->intf->dev,
+				"usb_submit_urb failed (%d)\n", retval);
+			dev->buffer_overflow = 1;
+		}
+	}
+	spin_unlock(&dev->rbsl);
+exit:
+	dev->interrupt_in_done = 1;
+	wake_up_interruptible(&dev->read_wait);
+}
+
+/**
+ *	ld_usb_interrupt_out_callback
+ */
+static void ld_usb_interrupt_out_callback(struct urb *urb)
+{
+	struct ld_usb *dev = urb->context;
+	int status = urb->status;
+
+	/* sync/async unlink faults aren't errors */
+	if (status && !(status == -ENOENT ||
+			status == -ECONNRESET ||
+			status == -ESHUTDOWN))
+		dev_dbg(&dev->intf->dev,
+			"%s - nonzero write interrupt status received: %d\n",
+			__func__, status);
+
+	dev->interrupt_out_busy = 0;
+	wake_up_interruptible(&dev->write_wait);
+}
+
+/**
+ *	ld_usb_open
+ */
+static int ld_usb_open(struct inode *inode, struct file *file)
+{
+	struct ld_usb *dev;
+	int subminor;
+	int retval;
+	struct usb_interface *interface;
+
+	nonseekable_open(inode, file);
+	subminor = iminor(inode);
+
+	interface = usb_find_interface(&ld_usb_driver, subminor);
+
+	if (!interface) {
+		printk(KERN_ERR "%s - error, can't find device for minor %d\n",
+		       __func__, subminor);
+		return -ENODEV;
+	}
+
+	dev = usb_get_intfdata(interface);
+
+	if (!dev)
+		return -ENODEV;
+
+	/* lock this device */
+	if (mutex_lock_interruptible(&dev->mutex))
+		return -ERESTARTSYS;
+
+	/* allow opening only once */
+	if (dev->open_count) {
+		retval = -EBUSY;
+		goto unlock_exit;
+	}
+	dev->open_count = 1;
+
+	/* initialize in direction */
+	dev->ring_head = 0;
+	dev->ring_tail = 0;
+	dev->buffer_overflow = 0;
+	usb_fill_int_urb(dev->interrupt_in_urb,
+			 interface_to_usbdev(interface),
+			 usb_rcvintpipe(interface_to_usbdev(interface),
+					dev->interrupt_in_endpoint->bEndpointAddress),
+			 dev->interrupt_in_buffer,
+			 dev->interrupt_in_endpoint_size,
+			 ld_usb_interrupt_in_callback,
+			 dev,
+			 dev->interrupt_in_interval);
+
+	dev->interrupt_in_running = 1;
+	dev->interrupt_in_done = 0;
+
+	retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
+	if (retval) {
+		dev_err(&interface->dev, "Couldn't submit interrupt_in_urb %d\n", retval);
+		dev->interrupt_in_running = 0;
+		dev->open_count = 0;
+		goto unlock_exit;
+	}
+
+	/* save device in the file's private structure */
+	file->private_data = dev;
+
+unlock_exit:
+	mutex_unlock(&dev->mutex);
+
+	return retval;
+}
+
+/**
+ *	ld_usb_release
+ */
+static int ld_usb_release(struct inode *inode, struct file *file)
+{
+	struct ld_usb *dev;
+	int retval = 0;
+
+	dev = file->private_data;
+
+	if (dev == NULL) {
+		retval = -ENODEV;
+		goto exit;
+	}
+
+	if (mutex_lock_interruptible(&dev->mutex)) {
+		retval = -ERESTARTSYS;
+		goto exit;
+	}
+
+	if (dev->open_count != 1) {
+		retval = -ENODEV;
+		goto unlock_exit;
+	}
+	if (dev->intf == NULL) {
+		/* the device was unplugged before the file was released */
+		mutex_unlock(&dev->mutex);
+		/* unlock here as ld_usb_delete frees dev */
+		ld_usb_delete(dev);
+		goto exit;
+	}
+
+	/* wait until write transfer is finished */
+	if (dev->interrupt_out_busy)
+		wait_event_interruptible_timeout(dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
+	ld_usb_abort_transfers(dev);
+	dev->open_count = 0;
+
+unlock_exit:
+	mutex_unlock(&dev->mutex);
+
+exit:
+	return retval;
+}
+
+/**
+ *	ld_usb_poll
+ */
+static unsigned int ld_usb_poll(struct file *file, poll_table *wait)
+{
+	struct ld_usb *dev;
+	unsigned int mask = 0;
+
+	dev = file->private_data;
+
+	if (!dev->intf)
+		return POLLERR | POLLHUP;
+
+	poll_wait(file, &dev->read_wait, wait);
+	poll_wait(file, &dev->write_wait, wait);
+
+	if (dev->ring_head != dev->ring_tail)
+		mask |= POLLIN | POLLRDNORM;
+	if (!dev->interrupt_out_busy)
+		mask |= POLLOUT | POLLWRNORM;
+
+	return mask;
+}
+
+/**
+ *	ld_usb_read
+ */
+static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count,
+			   loff_t *ppos)
+{
+	struct ld_usb *dev;
+	size_t *actual_buffer;
+	size_t bytes_to_read;
+	int retval = 0;
+	int rv;
+
+	dev = file->private_data;
+
+	/* verify that we actually have some data to read */
+	if (count == 0)
+		goto exit;
+
+	/* lock this object */
+	if (mutex_lock_interruptible(&dev->mutex)) {
+		retval = -ERESTARTSYS;
+		goto exit;
+	}
+
+	/* verify that the device wasn't unplugged */
+	if (dev->intf == NULL) {
+		retval = -ENODEV;
+		printk(KERN_ERR "ldusb: No device or device unplugged %d\n", retval);
+		goto unlock_exit;
+	}
+
+	/* wait for data */
+	spin_lock_irq(&dev->rbsl);
+	if (dev->ring_head == dev->ring_tail) {
+		dev->interrupt_in_done = 0;
+		spin_unlock_irq(&dev->rbsl);
+		if (file->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			goto unlock_exit;
+		}
+		retval = wait_event_interruptible(dev->read_wait, dev->interrupt_in_done);
+		if (retval < 0)
+			goto unlock_exit;
+	} else {
+		spin_unlock_irq(&dev->rbsl);
+	}
+
+	/* actual_buffer contains actual_length + interrupt_in_buffer */
+	actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_tail*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
+	bytes_to_read = min(count, *actual_buffer);
+	if (bytes_to_read < *actual_buffer)
+		dev_warn(&dev->intf->dev, "Read buffer overflow, %zd bytes dropped\n",
+			 *actual_buffer-bytes_to_read);
+
+	/* copy one interrupt_in_buffer from ring_buffer into userspace */
+	if (copy_to_user(buffer, actual_buffer+1, bytes_to_read)) {
+		retval = -EFAULT;
+		goto unlock_exit;
+	}
+	dev->ring_tail = (dev->ring_tail+1) % ring_buffer_size;
+
+	retval = bytes_to_read;
+
+	spin_lock_irq(&dev->rbsl);
+	if (dev->buffer_overflow) {
+		dev->buffer_overflow = 0;
+		spin_unlock_irq(&dev->rbsl);
+		rv = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
+		if (rv < 0)
+			dev->buffer_overflow = 1;
+	} else {
+		spin_unlock_irq(&dev->rbsl);
+	}
+
+unlock_exit:
+	/* unlock the device */
+	mutex_unlock(&dev->mutex);
+
+exit:
+	return retval;
+}
+
+/**
+ *	ld_usb_write
+ */
+static ssize_t ld_usb_write(struct file *file, const char __user *buffer,
+			    size_t count, loff_t *ppos)
+{
+	struct ld_usb *dev;
+	size_t bytes_to_write;
+	int retval = 0;
+
+	dev = file->private_data;
+
+	/* verify that we actually have some data to write */
+	if (count == 0)
+		goto exit;
+
+	/* lock this object */
+	if (mutex_lock_interruptible(&dev->mutex)) {
+		retval = -ERESTARTSYS;
+		goto exit;
+	}
+
+	/* verify that the device wasn't unplugged */
+	if (dev->intf == NULL) {
+		retval = -ENODEV;
+		printk(KERN_ERR "ldusb: No device or device unplugged %d\n", retval);
+		goto unlock_exit;
+	}
+
+	/* wait until previous transfer is finished */
+	if (dev->interrupt_out_busy) {
+		if (file->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			goto unlock_exit;
+		}
+		retval = wait_event_interruptible(dev->write_wait, !dev->interrupt_out_busy);
+		if (retval < 0) {
+			goto unlock_exit;
+		}
+	}
+
+	/* write the data into interrupt_out_buffer from userspace */
+	bytes_to_write = min(count, write_buffer_size*dev->interrupt_out_endpoint_size);
+	if (bytes_to_write < count)
+		dev_warn(&dev->intf->dev, "Write buffer overflow, %zd bytes dropped\n",count-bytes_to_write);
+	dev_dbg(&dev->intf->dev, "%s: count = %zd, bytes_to_write = %zd\n",
+		__func__, count, bytes_to_write);
+
+	if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write)) {
+		retval = -EFAULT;
+		goto unlock_exit;
+	}
+
+	if (dev->interrupt_out_endpoint == NULL) {
+		/* try HID_REQ_SET_REPORT=9 on control_endpoint instead of interrupt_out_endpoint */
+		retval = usb_control_msg(interface_to_usbdev(dev->intf),
+					 usb_sndctrlpipe(interface_to_usbdev(dev->intf), 0),
+					 9,
+					 USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
+					 1 << 8, 0,
+					 dev->interrupt_out_buffer,
+					 bytes_to_write,
+					 USB_CTRL_SET_TIMEOUT * HZ);
+		if (retval < 0)
+			dev_err(&dev->intf->dev,
+				"Couldn't submit HID_REQ_SET_REPORT %d\n",
+				retval);
+		goto unlock_exit;
+	}
+
+	/* send off the urb */
+	usb_fill_int_urb(dev->interrupt_out_urb,
+			 interface_to_usbdev(dev->intf),
+			 usb_sndintpipe(interface_to_usbdev(dev->intf),
+					dev->interrupt_out_endpoint->bEndpointAddress),
+			 dev->interrupt_out_buffer,
+			 bytes_to_write,
+			 ld_usb_interrupt_out_callback,
+			 dev,
+			 dev->interrupt_out_interval);
+
+	dev->interrupt_out_busy = 1;
+	wmb();
+
+	retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
+	if (retval) {
+		dev->interrupt_out_busy = 0;
+		dev_err(&dev->intf->dev,
+			"Couldn't submit interrupt_out_urb %d\n", retval);
+		goto unlock_exit;
+	}
+	retval = bytes_to_write;
+
+unlock_exit:
+	/* unlock the device */
+	mutex_unlock(&dev->mutex);
+
+exit:
+	return retval;
+}
+
+/* file operations needed when we register this driver */
+static const struct file_operations ld_usb_fops = {
+	.owner =	THIS_MODULE,
+	.read  =	ld_usb_read,
+	.write =	ld_usb_write,
+	.open =		ld_usb_open,
+	.release =	ld_usb_release,
+	.poll =		ld_usb_poll,
+	.llseek =	no_llseek,
+};
+
+/*
+ * usb class driver info in order to get a minor number from the usb core,
+ * and to have the device registered with the driver core
+ */
+static struct usb_class_driver ld_usb_class = {
+	.name =		"ldusb%d",
+	.fops =		&ld_usb_fops,
+	.minor_base =	USB_LD_MINOR_BASE,
+};
+
+/**
+ *	ld_usb_probe
+ *
+ *	Called by the usb core when a new device is connected that it thinks
+ *	this driver might be interested in.
+ */
+static int ld_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
+{
+	struct usb_device *udev = interface_to_usbdev(intf);
+	struct ld_usb *dev = NULL;
+	struct usb_host_interface *iface_desc;
+	struct usb_endpoint_descriptor *endpoint;
+	char *buffer;
+	int i;
+	int retval = -ENOMEM;
+
+	/* allocate memory for our device state and initialize it */
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (dev == NULL) {
+		dev_err(&intf->dev, "Out of memory\n");
+		goto exit;
+	}
+	mutex_init(&dev->mutex);
+	spin_lock_init(&dev->rbsl);
+	dev->intf = intf;
+	init_waitqueue_head(&dev->read_wait);
+	init_waitqueue_head(&dev->write_wait);
+
+	/* workaround for early firmware versions on fast computers */
+	if ((le16_to_cpu(udev->descriptor.idVendor) == USB_VENDOR_ID_LD) &&
+	    ((le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_LD_CASSY) ||
+	     (le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_LD_COM3LAB)) &&
+	    (le16_to_cpu(udev->descriptor.bcdDevice) <= 0x103)) {
+		buffer = kmalloc(256, GFP_KERNEL);
+		if (buffer == NULL) {
+			dev_err(&intf->dev, "Couldn't allocate string buffer\n");
+			goto error;
+		}
+		/* usb_string makes SETUP+STALL to leave always ControlReadLoop */
+		usb_string(udev, 255, buffer, 256);
+		kfree(buffer);
+	}
+
+	iface_desc = intf->cur_altsetting;
+
+	/* 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(&intf->dev, "Interrupt in endpoint not found\n");
+		goto error;
+	}
+	if (dev->interrupt_out_endpoint == NULL)
+		dev_warn(&intf->dev, "Interrupt out endpoint not found (using control endpoint instead)\n");
+
+	dev->interrupt_in_endpoint_size = usb_endpoint_maxp(dev->interrupt_in_endpoint);
+	dev->ring_buffer = kmalloc(ring_buffer_size*(sizeof(size_t)+dev->interrupt_in_endpoint_size), GFP_KERNEL);
+	if (!dev->ring_buffer) {
+		dev_err(&intf->dev, "Couldn't allocate ring_buffer\n");
+		goto error;
+	}
+	dev->interrupt_in_buffer = kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
+	if (!dev->interrupt_in_buffer) {
+		dev_err(&intf->dev, "Couldn't allocate interrupt_in_buffer\n");
+		goto error;
+	}
+	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!dev->interrupt_in_urb) {
+		dev_err(&intf->dev, "Couldn't allocate interrupt_in_urb\n");
+		goto error;
+	}
+	dev->interrupt_out_endpoint_size = dev->interrupt_out_endpoint ? usb_endpoint_maxp(dev->interrupt_out_endpoint) :
+									 udev->descriptor.bMaxPacketSize0;
+	dev->interrupt_out_buffer = kmalloc(write_buffer_size*dev->interrupt_out_endpoint_size, GFP_KERNEL);
+	if (!dev->interrupt_out_buffer) {
+		dev_err(&intf->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(&intf->dev, "Couldn't allocate interrupt_out_urb\n");
+		goto error;
+	}
+	dev->interrupt_in_interval = min_interrupt_in_interval > dev->interrupt_in_endpoint->bInterval ? min_interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
+	if (dev->interrupt_out_endpoint)
+		dev->interrupt_out_interval = min_interrupt_out_interval > dev->interrupt_out_endpoint->bInterval ? min_interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
+
+	/* we can register the device now, as it is ready */
+	usb_set_intfdata(intf, dev);
+
+	retval = usb_register_dev(intf, &ld_usb_class);
+	if (retval) {
+		/* something prevented us from registering this driver */
+		dev_err(&intf->dev, "Not able to get a minor for this device.\n");
+		usb_set_intfdata(intf, NULL);
+		goto error;
+	}
+
+	/* let the user know what node this device is now attached to */
+	dev_info(&intf->dev, "LD USB Device #%d now attached to major %d minor %d\n",
+		(intf->minor - USB_LD_MINOR_BASE), USB_MAJOR, intf->minor);
+
+exit:
+	return retval;
+
+error:
+	ld_usb_delete(dev);
+
+	return retval;
+}
+
+/**
+ *	ld_usb_disconnect
+ *
+ *	Called by the usb core when the device is removed from the system.
+ */
+static void ld_usb_disconnect(struct usb_interface *intf)
+{
+	struct ld_usb *dev;
+	int minor;
+
+	dev = usb_get_intfdata(intf);
+	usb_set_intfdata(intf, NULL);
+
+	minor = intf->minor;
+
+	/* give back our minor */
+	usb_deregister_dev(intf, &ld_usb_class);
+
+	mutex_lock(&dev->mutex);
+
+	/* if the device is not opened, then we clean up right now */
+	if (!dev->open_count) {
+		mutex_unlock(&dev->mutex);
+		ld_usb_delete(dev);
+	} else {
+		dev->intf = NULL;
+		/* wake up pollers */
+		wake_up_interruptible_all(&dev->read_wait);
+		wake_up_interruptible_all(&dev->write_wait);
+		mutex_unlock(&dev->mutex);
+	}
+
+	dev_info(&intf->dev, "LD USB Device #%d now disconnected\n",
+		 (minor - USB_LD_MINOR_BASE));
+}
+
+/* usb specific object needed to register this driver with the usb subsystem */
+static struct usb_driver ld_usb_driver = {
+	.name =		"ldusb",
+	.probe =	ld_usb_probe,
+	.disconnect =	ld_usb_disconnect,
+	.id_table =	ld_usb_table,
+};
+
+module_usb_driver(ld_usb_driver);
+