diff --git a/drivers/usb/mon/mon_main.c b/drivers/usb/mon/mon_main.c
new file mode 100644
index 0000000..aa9d008
--- /dev/null
+++ b/drivers/usb/mon/mon_main.c
@@ -0,0 +1,377 @@
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ *
+ * mon_main.c: Main file, module initiation and exit, registrations, etc.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/debugfs.h>
+#include <linux/smp_lock.h>
+
+#include "usb_mon.h"
+#include "../core/hcd.h"
+
+static void mon_submit(struct usb_bus *ubus, struct urb *urb);
+static void mon_complete(struct usb_bus *ubus, struct urb *urb);
+static void mon_stop(struct mon_bus *mbus);
+static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus);
+static void mon_bus_drop(struct kref *r);
+static void mon_bus_init(struct dentry *mondir, struct usb_bus *ubus);
+
+DECLARE_MUTEX(mon_lock);
+
+static struct dentry *mon_dir;		/* /dbg/usbmon */
+static LIST_HEAD(mon_buses);		/* All buses we know: struct mon_bus */
+
+/*
+ * Link a reader into the bus.
+ *
+ * This must be called with mon_lock taken because of mbus->ref.
+ */
+void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r)
+{
+	unsigned long flags;
+	struct usb_bus *ubus;
+
+	spin_lock_irqsave(&mbus->lock, flags);
+	if (mbus->nreaders == 0) {
+		ubus = mbus->u_bus;
+		if (ubus->monitored) {
+			/*
+			 * Something is really broken, refuse to go on and
+			 * possibly corrupt ops pointers or worse.
+			 */
+			printk(KERN_ERR TAG ": bus %d is already monitored\n",
+			    ubus->busnum);
+			spin_unlock_irqrestore(&mbus->lock, flags);
+			return;
+		}
+		ubus->monitored = 1;
+	}
+	mbus->nreaders++;
+	list_add_tail(&r->r_link, &mbus->r_list);
+	spin_unlock_irqrestore(&mbus->lock, flags);
+
+	kref_get(&mbus->ref);
+}
+
+/*
+ * Unlink reader from the bus.
+ *
+ * This is called with mon_lock taken, so we can decrement mbus->ref.
+ */
+void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&mbus->lock, flags);
+	list_del(&r->r_link);
+	--mbus->nreaders;
+	if (mbus->nreaders == 0)
+		mon_stop(mbus);
+	spin_unlock_irqrestore(&mbus->lock, flags);
+
+	kref_put(&mbus->ref, mon_bus_drop);
+}
+
+/*
+ */
+static void mon_submit(struct usb_bus *ubus, struct urb *urb)
+{
+	struct mon_bus *mbus;
+	unsigned long flags;
+	struct list_head *pos;
+	struct mon_reader *r;
+
+	mbus = ubus->mon_bus;
+	if (mbus == NULL)
+		goto out_unlocked;
+
+	spin_lock_irqsave(&mbus->lock, flags);
+	if (mbus->nreaders == 0)
+		goto out_locked;
+
+	list_for_each (pos, &mbus->r_list) {
+		r = list_entry(pos, struct mon_reader, r_link);
+		r->rnf_submit(r->r_data, urb);
+	}
+
+	spin_unlock_irqrestore(&mbus->lock, flags);
+	return;
+
+out_locked:
+	spin_unlock_irqrestore(&mbus->lock, flags);
+out_unlocked:
+	return;
+}
+
+/*
+ */
+static void mon_submit_error(struct usb_bus *ubus, struct urb *urb, int err)
+{
+	struct mon_bus *mbus;
+
+	mbus = ubus->mon_bus;
+	if (mbus == NULL)
+		goto out_unlocked;
+
+	/*
+	 * XXX Capture the error code and the 'E' event.
+	 */
+
+	return;
+
+out_unlocked:
+	return;
+}
+
+/*
+ */
+static void mon_complete(struct usb_bus *ubus, struct urb *urb)
+{
+	struct mon_bus *mbus;
+	unsigned long flags;
+	struct list_head *pos;
+	struct mon_reader *r;
+
+	mbus = ubus->mon_bus;
+	if (mbus == NULL) {
+		/*
+		 * This should not happen.
+		 * At this point we do not even know the bus number...
+		 */
+		printk(KERN_ERR TAG ": Null mon bus in URB, pipe 0x%x\n",
+		    urb->pipe);
+		return;
+	}
+
+	spin_lock_irqsave(&mbus->lock, flags);
+	list_for_each (pos, &mbus->r_list) {
+		r = list_entry(pos, struct mon_reader, r_link);
+		r->rnf_complete(r->r_data, urb);
+	}
+	spin_unlock_irqrestore(&mbus->lock, flags);
+}
+
+/* int (*unlink_urb) (struct urb *urb, int status); */
+
+/*
+ * Stop monitoring.
+ * Obviously this must be well locked, so no need to play with mb's.
+ */
+static void mon_stop(struct mon_bus *mbus)
+{
+	struct usb_bus *ubus = mbus->u_bus;
+
+	/*
+	 * A stop can be called for a dissolved mon_bus in case of
+	 * a reader staying across an rmmod foo_hcd.
+	 */
+	if (ubus != NULL) {
+		ubus->monitored = 0;
+		mb();
+	}
+}
+
+/*
+ * Add a USB bus (usually by a modprobe foo-hcd)
+ *
+ * This does not return an error code because the core cannot care less
+ * if monitoring is not established.
+ */
+static void mon_bus_add(struct usb_bus *ubus)
+{
+	mon_bus_init(mon_dir, ubus);
+}
+
+/*
+ * Remove a USB bus (either from rmmod foo-hcd or from a hot-remove event).
+ */
+static void mon_bus_remove(struct usb_bus *ubus)
+{
+	struct mon_bus *mbus = ubus->mon_bus;
+
+	down(&mon_lock);
+	list_del(&mbus->bus_link);
+	debugfs_remove(mbus->dent_t);
+	debugfs_remove(mbus->dent_s);
+
+	mon_dissolve(mbus, ubus);
+	kref_put(&mbus->ref, mon_bus_drop);
+	up(&mon_lock);
+}
+
+/*
+ * Ops
+ */
+static struct usb_mon_operations mon_ops_0 = {
+	.urb_submit =	mon_submit,
+	.urb_submit_error = mon_submit_error,
+	.urb_complete =	mon_complete,
+	.bus_add =	mon_bus_add,
+	.bus_remove =	mon_bus_remove,
+};
+
+/*
+ * Tear usb_bus and mon_bus apart.
+ */
+static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
+{
+
+	/*
+	 * Never happens, but...
+	 */
+	if (ubus->monitored) {
+		printk(KERN_ERR TAG ": bus %d is dissolved while monitored\n",
+		    ubus->busnum);
+		ubus->monitored = 0;
+		mb();
+	}
+
+	ubus->mon_bus = NULL;
+	mbus->u_bus = NULL;
+	mb();
+	// usb_bus_put(ubus);
+}
+
+/*
+ */
+static void mon_bus_drop(struct kref *r)
+{
+	struct mon_bus *mbus = container_of(r, struct mon_bus, ref);
+	kfree(mbus);
+}
+
+/*
+ * Initialize a bus for us:
+ *  - allocate mon_bus
+ *  - refcount USB bus struct
+ *  - link
+ */
+static void mon_bus_init(struct dentry *mondir, struct usb_bus *ubus)
+{
+	struct dentry *d;
+	struct mon_bus *mbus;
+	enum { NAMESZ = 10 };
+	char name[NAMESZ];
+	int rc;
+
+	if ((mbus = kmalloc(sizeof(struct mon_bus), GFP_KERNEL)) == NULL)
+		goto err_alloc;
+	memset(mbus, 0, sizeof(struct mon_bus));
+	kref_init(&mbus->ref);
+	spin_lock_init(&mbus->lock);
+	INIT_LIST_HEAD(&mbus->r_list);
+
+	/*
+	 * This usb_bus_get here is superfluous, because we receive
+	 * a notification if usb_bus is about to be removed.
+	 */
+	// usb_bus_get(ubus);
+	mbus->u_bus = ubus;
+	ubus->mon_bus = mbus;
+
+	rc = snprintf(name, NAMESZ, "%dt", ubus->busnum);
+	if (rc <= 0 || rc >= NAMESZ)
+		goto err_print_t;
+	d = debugfs_create_file(name, 0600, mondir, mbus, &mon_fops_text);
+	if (d == NULL)
+		goto err_create_t;
+	mbus->dent_t = d;
+
+	rc = snprintf(name, NAMESZ, "%ds", ubus->busnum);
+	if (rc <= 0 || rc >= NAMESZ)
+		goto err_print_s;
+	d = debugfs_create_file(name, 0600, mondir, mbus, &mon_fops_stat);
+	if (d == NULL)
+		goto err_create_s;
+	mbus->dent_s = d;
+
+	down(&mon_lock);
+	list_add_tail(&mbus->bus_link, &mon_buses);
+	up(&mon_lock);
+	return;
+
+err_create_s:
+err_print_s:
+	debugfs_remove(mbus->dent_t);
+err_create_t:
+err_print_t:
+	kfree(mbus);
+err_alloc:
+	return;
+}
+
+static int __init mon_init(void)
+{
+	struct usb_bus *ubus;
+	struct dentry *mondir;
+
+	mondir = debugfs_create_dir("usbmon", NULL);
+	if (IS_ERR(mondir)) {
+		printk(KERN_NOTICE TAG ": debugs is not available\n");
+		return -ENODEV;
+	}
+	if (mondir == NULL) {
+		printk(KERN_NOTICE TAG ": unable to create usbmon directory\n");
+		return -ENODEV;
+	}
+	mon_dir = mondir;
+
+	if (usb_mon_register(&mon_ops_0) != 0) {
+		printk(KERN_NOTICE TAG ": unable to register with the core\n");
+		debugfs_remove(mondir);
+		return -ENODEV;
+	}
+	// MOD_INC_USE_COUNT(which_module?);
+
+	down(&usb_bus_list_lock);
+	list_for_each_entry (ubus, &usb_bus_list, bus_list) {
+		mon_bus_init(mondir, ubus);
+	}
+	up(&usb_bus_list_lock);
+	return 0;
+}
+
+static void __exit mon_exit(void)
+{
+	struct mon_bus *mbus;
+	struct list_head *p;
+
+	usb_mon_deregister();
+
+	down(&mon_lock);
+	while (!list_empty(&mon_buses)) {
+		p = mon_buses.next;
+		mbus = list_entry(p, struct mon_bus, bus_link);
+		list_del(p);
+
+		debugfs_remove(mbus->dent_t);
+		debugfs_remove(mbus->dent_s);
+
+		/*
+		 * This never happens, because the open/close paths in
+		 * file level maintain module use counters and so rmmod fails
+		 * before reaching here. However, better be safe...
+		 */
+		if (mbus->nreaders) {
+			printk(KERN_ERR TAG
+			    ": Outstanding opens (%d) on usb%d, leaking...\n",
+			    mbus->nreaders, mbus->u_bus->busnum);
+			atomic_set(&mbus->ref.refcount, 2);	/* Force leak */
+		}
+
+		mon_dissolve(mbus, mbus->u_bus);
+		kref_put(&mbus->ref, mon_bus_drop);
+	}
+	up(&mon_lock);
+
+	debugfs_remove(mon_dir);
+}
+
+module_init(mon_init);
+module_exit(mon_exit);
+
+MODULE_LICENSE("GPL");