diff --git a/drivers/usb/mon/Kconfig b/drivers/usb/mon/Kconfig
new file mode 100644
index 0000000..4e6152a
--- /dev/null
+++ b/drivers/usb/mon/Kconfig
@@ -0,0 +1,22 @@
+#
+# USB Monitor configuration
+#
+
+# In normal life, it makes little sense to have usbmon as a module, and in fact
+# it is harmful, because there is no way to autoload the module.
+# The 'm' option is allowed for hackers who debug the usbmon itself,
+# and for those who have usbcore as a module.
+config USB_MON
+	tristate "USB Monitor"
+	depends on USB
+	default y
+	help
+	  If you say Y here, a component which captures the USB traffic
+	  between peripheral-specific drivers and HC drivers will be built.
+	  The USB_MON is similar in spirit and may be compatible with Dave
+	  Harding's USBMon.
+
+	  This is somewhat experimental at this time, but it should be safe,
+	  as long as you aren't building this as a module and then removing it.
+
+	  If unsure, say Y. Do not say M.
diff --git a/drivers/usb/mon/Makefile b/drivers/usb/mon/Makefile
new file mode 100644
index 0000000..3cff8d4
--- /dev/null
+++ b/drivers/usb/mon/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for USB Core files and filesystem
+#
+
+usbmon-objs	:= mon_main.o mon_stat.o mon_text.o
+
+obj-$(CONFIG_USB_MON)	+= usbmon.o
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");
diff --git a/drivers/usb/mon/mon_stat.c b/drivers/usb/mon/mon_stat.c
new file mode 100644
index 0000000..6e4b165
--- /dev/null
+++ b/drivers/usb/mon/mon_stat.c
@@ -0,0 +1,74 @@
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ *
+ * This is the 's' or 'stat' reader which debugs usbmon itself.
+ * Note that this code blows through locks, so make sure that
+ * /dbg/usbmon/0s is well protected from non-root users.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/usb.h>
+#include <asm/uaccess.h>
+
+#include "usb_mon.h"
+
+#define STAT_BUF_SIZE  80
+
+struct snap {
+	int slen;
+	char str[STAT_BUF_SIZE];
+};
+
+static int mon_stat_open(struct inode *inode, struct file *file)
+{
+	struct mon_bus *mbus;
+	struct snap *sp;
+
+	if ((sp = kmalloc(sizeof(struct snap), GFP_KERNEL)) == NULL)
+		return -ENOMEM;
+
+	mbus = inode->u.generic_ip;
+
+	sp->slen = snprintf(sp->str, STAT_BUF_SIZE,
+	    "nreaders %d text_lost %u\n",
+	    mbus->nreaders, mbus->cnt_text_lost);
+
+	file->private_data = sp;
+	return 0;
+}
+
+static ssize_t mon_stat_read(struct file *file, char __user *buf,
+				size_t nbytes, loff_t *ppos)
+{
+	struct snap *sp = file->private_data;
+	loff_t pos = *ppos;
+	int cnt;
+
+	if (pos < 0 || pos >= sp->slen)
+		return 0;
+	if (nbytes == 0)
+		return 0;
+	if ((cnt = sp->slen - pos) > nbytes)
+		cnt = nbytes;
+	if (copy_to_user(buf, sp->str + pos, cnt))
+		return -EFAULT;
+	*ppos = pos + cnt;
+	return cnt;
+}
+
+static int mon_stat_release(struct inode *inode, struct file *file)
+{
+	return 0;
+}
+
+struct file_operations mon_fops_stat = {
+	.owner =	THIS_MODULE,
+	.open =		mon_stat_open,
+	.llseek =	no_llseek,
+	.read =		mon_stat_read,
+	/* .write =	mon_stat_write, */
+	/* .poll =		mon_stat_poll, */
+	/* .ioctl =	mon_stat_ioctl, */
+	.release =	mon_stat_release,
+};
diff --git a/drivers/usb/mon/mon_text.c b/drivers/usb/mon/mon_text.c
new file mode 100644
index 0000000..755a457
--- /dev/null
+++ b/drivers/usb/mon/mon_text.c
@@ -0,0 +1,405 @@
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ *
+ * This is a text format reader.
+ */
+
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/usb.h>
+#include <linux/time.h>
+#include <asm/uaccess.h>
+
+#include "usb_mon.h"
+
+/*
+ * No, we do not want arbitrarily long data strings.
+ * Use the binary interface if you want to capture bulk data!
+ */
+#define DATA_MAX  32
+
+/*
+ * This limit exists to prevent OOMs when the user process stops reading.
+ */
+#define EVENT_MAX  25
+
+#define PRINTF_DFL  120
+
+struct mon_event_text {
+	struct list_head e_link;
+	int type;		/* submit, complete, etc. */
+	unsigned int pipe;	/* Pipe */
+	unsigned long id;	/* From pointer, most of the time */
+	unsigned int tstamp;
+	int length;		/* Depends on type: xfer length or act length */
+	int status;
+	char data_flag;
+	unsigned char data[DATA_MAX];
+};
+
+#define SLAB_NAME_SZ  30
+struct mon_reader_text {
+	kmem_cache_t *e_slab;
+	int nevents;
+	struct list_head e_list;
+	struct mon_reader r;	/* In C, parent class can be placed anywhere */
+
+	wait_queue_head_t wait;
+	int printf_size;
+	char *printf_buf;
+	struct semaphore printf_lock;
+
+	char slab_name[SLAB_NAME_SZ];
+};
+
+static void mon_text_ctor(void *, kmem_cache_t *, unsigned long);
+static void mon_text_dtor(void *, kmem_cache_t *, unsigned long);
+
+/*
+ * mon_text_submit
+ * mon_text_complete
+ *
+ * May be called from an interrupt.
+ *
+ * This is called with the whole mon_bus locked, so no additional lock.
+ */
+
+static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
+    int len, char ev_type)
+{
+	int pipe = urb->pipe;
+	unsigned char *data;
+
+	/*
+	 * The check to see if it's safe to poke at data has an enormous
+	 * number of corner cases, but it seems that the following is
+	 * more or less safe.
+	 *
+	 * We do not even try to look transfer_buffer, because it can
+	 * contain non-NULL garbage in case the upper level promised to
+	 * set DMA for the HCD.
+	 */
+	if (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
+		return 'D';
+
+	if (len <= 0)
+		return 'L';
+
+	if ((data = urb->transfer_buffer) == NULL)
+		return 'Z';	/* '0' would be not as pretty. */
+
+	/*
+	 * Bulk is easy to shortcut reliably. 
+	 * XXX Control needs setup packet taken.
+	 * XXX Other pipe types need consideration. Currently, we overdo it
+	 * and collect garbage for them: better more than less.
+	 */
+	if (usb_pipebulk(pipe) || usb_pipecontrol(pipe)) {
+		if (usb_pipein(pipe)) {
+			if (ev_type == 'S')
+				return '<';
+		} else {
+			if (ev_type == 'C')
+				return '>';
+		}
+	}
+
+	if (len >= DATA_MAX)
+		len = DATA_MAX;
+	memcpy(ep->data, urb->transfer_buffer, len);
+	return 0;
+}
+
+static inline unsigned int mon_get_timestamp(void)
+{
+	struct timeval tval;
+	unsigned int stamp;
+
+	do_gettimeofday(&tval);
+	stamp = tval.tv_sec & 0xFFFF;	/* 2^32 = 4294967296. Limit to 4096s. */
+	stamp = stamp * 1000000 + tval.tv_usec;
+	return stamp;
+}
+
+static void mon_text_event(struct mon_reader_text *rp, struct urb *urb,
+    char ev_type)
+{
+	struct mon_event_text *ep;
+	unsigned int stamp;
+
+	stamp = mon_get_timestamp();
+
+	if (rp->nevents >= EVENT_MAX ||
+	    (ep = kmem_cache_alloc(rp->e_slab, SLAB_ATOMIC)) == NULL) {
+		rp->r.m_bus->cnt_text_lost++;
+		return;
+	}
+
+	ep->type = ev_type;
+	ep->pipe = urb->pipe;
+	ep->id = (unsigned long) urb;
+	ep->tstamp = stamp;
+	ep->length = (ev_type == 'S') ?
+	    urb->transfer_buffer_length : urb->actual_length;
+	/* Collecting status makes debugging sense for submits, too */
+	ep->status = urb->status;
+
+	ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type);
+
+	rp->nevents++;
+	list_add_tail(&ep->e_link, &rp->e_list);
+	wake_up(&rp->wait);
+}
+
+static void mon_text_submit(void *data, struct urb *urb)
+{
+	struct mon_reader_text *rp = data;
+	mon_text_event(rp, urb, 'S');
+}
+
+static void mon_text_complete(void *data, struct urb *urb)
+{
+	struct mon_reader_text *rp = data;
+	mon_text_event(rp, urb, 'C');
+}
+
+/*
+ * Fetch next event from the circular buffer.
+ */
+static struct mon_event_text *mon_text_fetch(struct mon_reader_text *rp,
+    struct mon_bus *mbus)
+{
+	struct list_head *p;
+	unsigned long flags;
+
+	spin_lock_irqsave(&mbus->lock, flags);
+	if (list_empty(&rp->e_list)) {
+		spin_unlock_irqrestore(&mbus->lock, flags);
+		return NULL;
+	}
+	p = rp->e_list.next;
+	list_del(p);
+	--rp->nevents;
+	spin_unlock_irqrestore(&mbus->lock, flags);
+	return list_entry(p, struct mon_event_text, e_link);
+}
+
+/*
+ */
+static int mon_text_open(struct inode *inode, struct file *file)
+{
+	struct mon_bus *mbus;
+	struct usb_bus *ubus;
+	struct mon_reader_text *rp;
+	int rc;
+
+	down(&mon_lock);
+	mbus = inode->u.generic_ip;
+	ubus = mbus->u_bus;
+
+	rp = kmalloc(sizeof(struct mon_reader_text), GFP_KERNEL);
+	if (rp == NULL) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+	memset(rp, 0, sizeof(struct mon_reader_text));
+	INIT_LIST_HEAD(&rp->e_list);
+	init_waitqueue_head(&rp->wait);
+	init_MUTEX(&rp->printf_lock);
+
+	rp->printf_size = PRINTF_DFL;
+	rp->printf_buf = kmalloc(rp->printf_size, GFP_KERNEL);
+	if (rp->printf_buf == NULL) {
+		rc = -ENOMEM;
+		goto err_alloc_pr;
+	}
+
+	rp->r.m_bus = mbus;
+	rp->r.r_data = rp;
+	rp->r.rnf_submit = mon_text_submit;
+	rp->r.rnf_complete = mon_text_complete;
+
+	snprintf(rp->slab_name, SLAB_NAME_SZ, "mon%dt_%lx", ubus->busnum,
+	    (long)rp);
+	rp->e_slab = kmem_cache_create(rp->slab_name,
+	    sizeof(struct mon_event_text), sizeof(long), 0,
+	    mon_text_ctor, mon_text_dtor);
+	if (rp->e_slab == NULL) {
+		rc = -ENOMEM;
+		goto err_slab;
+	}
+
+	mon_reader_add(mbus, &rp->r);
+
+	file->private_data = rp;
+	up(&mon_lock);
+	return 0;
+
+// err_busy:
+//	kmem_cache_destroy(rp->e_slab);
+err_slab:
+	kfree(rp->printf_buf);
+err_alloc_pr:
+	kfree(rp);
+err_alloc:
+	up(&mon_lock);
+	return rc;
+}
+
+/*
+ * For simplicity, we read one record in one system call and throw out
+ * what does not fit. This means that the following does not work:
+ *   dd if=/dbg/usbmon/0t bs=10
+ * Also, we do not allow seeks and do not bother advancing the offset.
+ */
+static ssize_t mon_text_read(struct file *file, char __user *buf,
+				size_t nbytes, loff_t *ppos)
+{
+	struct mon_reader_text *rp = file->private_data;
+	struct mon_bus *mbus = rp->r.m_bus;
+	DECLARE_WAITQUEUE(waita, current);
+	struct mon_event_text *ep;
+	int cnt, limit;
+	char *pbuf;
+	char udir, utype;
+	int data_len, i;
+
+	add_wait_queue(&rp->wait, &waita);
+	set_current_state(TASK_INTERRUPTIBLE);
+	while ((ep = mon_text_fetch(rp, mbus)) == NULL) {
+		if (file->f_flags & O_NONBLOCK) {
+			set_current_state(TASK_RUNNING);
+			remove_wait_queue(&rp->wait, &waita);
+			return -EWOULDBLOCK;	/* Same as EAGAIN in Linux */
+		}
+		/*
+		 * We do not count nwaiters, because ->release is supposed
+		 * to be called when all openers are gone only.
+		 */
+		schedule();
+		if (signal_pending(current)) {
+			remove_wait_queue(&rp->wait, &waita);
+			return -EINTR;
+		}
+		set_current_state(TASK_INTERRUPTIBLE);
+	}
+	set_current_state(TASK_RUNNING);
+	remove_wait_queue(&rp->wait, &waita);
+
+	down(&rp->printf_lock);
+	cnt = 0;
+	pbuf = rp->printf_buf;
+	limit = rp->printf_size;
+
+	udir = usb_pipein(ep->pipe) ? 'i' : 'o';
+	switch (usb_pipetype(ep->pipe)) {
+	case PIPE_ISOCHRONOUS:	utype = 'Z'; break;
+	case PIPE_INTERRUPT:	utype = 'I'; break;
+	case PIPE_CONTROL:	utype = 'C'; break;
+	default: /* PIPE_BULK */  utype = 'B';
+	}
+	cnt += snprintf(pbuf + cnt, limit - cnt,
+	    "%lx %u %c %c%c:%03u:%02u %d %d",
+	    ep->id, ep->tstamp, ep->type,
+	    utype, udir, usb_pipedevice(ep->pipe), usb_pipeendpoint(ep->pipe),
+	    ep->status, ep->length);
+
+	if ((data_len = ep->length) > 0) {
+		if (ep->data_flag == 0) {
+			cnt += snprintf(pbuf + cnt, limit - cnt, " =");
+			if (data_len >= DATA_MAX)
+				data_len = DATA_MAX;
+			for (i = 0; i < data_len; i++) {
+				if (i % 4 == 0) {
+					cnt += snprintf(pbuf + cnt, limit - cnt,
+					    " ");
+				}
+				cnt += snprintf(pbuf + cnt, limit - cnt,
+				    "%02x", ep->data[i]);
+			}
+			cnt += snprintf(pbuf + cnt, limit - cnt, "\n");
+		} else {
+			cnt += snprintf(pbuf + cnt, limit - cnt,
+			    " %c\n", ep->data_flag);
+		}
+	} else {
+		cnt += snprintf(pbuf + cnt, limit - cnt, "\n");
+	}
+
+	if (copy_to_user(buf, rp->printf_buf, cnt))
+		cnt = -EFAULT;
+	up(&rp->printf_lock);
+	kmem_cache_free(rp->e_slab, ep);
+	return cnt;
+}
+
+static int mon_text_release(struct inode *inode, struct file *file)
+{
+	struct mon_reader_text *rp = file->private_data;
+	struct mon_bus *mbus;
+	/* unsigned long flags; */
+	struct list_head *p;
+	struct mon_event_text *ep;
+
+	down(&mon_lock);
+	mbus = inode->u.generic_ip;
+
+	if (mbus->nreaders <= 0) {
+		printk(KERN_ERR TAG ": consistency error on close\n");
+		up(&mon_lock);
+		return 0;
+	}
+	mon_reader_del(mbus, &rp->r);
+
+	/*
+	 * In theory, e_list is protected by mbus->lock. However,
+	 * after mon_reader_del has finished, the following is the case:
+	 *  - we are not on reader list anymore, so new events won't be added;
+	 *  - whole mbus may be dropped if it was orphaned.
+	 * So, we better not touch mbus.
+	 */
+	/* spin_lock_irqsave(&mbus->lock, flags); */
+	while (!list_empty(&rp->e_list)) {
+		p = rp->e_list.next;
+		ep = list_entry(p, struct mon_event_text, e_link);
+		list_del(p);
+		--rp->nevents;
+		kmem_cache_free(rp->e_slab, ep);
+	}
+	/* spin_unlock_irqrestore(&mbus->lock, flags); */
+
+	kmem_cache_destroy(rp->e_slab);
+	kfree(rp->printf_buf);
+	kfree(rp);
+
+	up(&mon_lock);
+	return 0;
+}
+
+struct file_operations mon_fops_text = {
+	.owner =	THIS_MODULE,
+	.open =		mon_text_open,
+	.llseek =	no_llseek,
+	.read =		mon_text_read,
+	/* .write =	mon_text_write, */
+	/* .poll =		mon_text_poll, */
+	/* .ioctl =	mon_text_ioctl, */
+	.release =	mon_text_release,
+};
+
+/*
+ * Slab interface: constructor.
+ */
+static void mon_text_ctor(void *mem, kmem_cache_t *slab, unsigned long sflags)
+{
+	/*
+	 * Nothing to initialize. No, really!
+	 * So, we fill it with garbage to emulate a reused object.
+	 */
+	memset(mem, 0xe5, sizeof(struct mon_event_text));
+}
+
+static void mon_text_dtor(void *mem, kmem_cache_t *slab, unsigned long sflags)
+{
+	;
+}
diff --git a/drivers/usb/mon/usb_mon.h b/drivers/usb/mon/usb_mon.h
new file mode 100644
index 0000000..ed35c18
--- /dev/null
+++ b/drivers/usb/mon/usb_mon.h
@@ -0,0 +1,51 @@
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ */
+
+#ifndef __USB_MON_H
+#define __USB_MON_H
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/kref.h>
+/* #include <linux/usb.h> */	/* We use struct pointers only in this header */
+
+#define TAG "usbmon"
+
+struct mon_bus {
+	struct list_head bus_link;
+	spinlock_t lock;
+	struct dentry *dent_s;		/* Debugging file */
+	struct dentry *dent_t;		/* Text interface file */
+	struct usb_bus *u_bus;
+
+	/* Ref */
+	int nreaders;			/* Under mon_lock AND mbus->lock */
+	struct list_head r_list;	/* Chain of readers (usually one) */
+	struct kref ref;		/* Under mon_lock */
+
+	/* Stats */
+	unsigned int cnt_text_lost;
+};
+
+/*
+ * An instance of a process which opened a file (but can fork later)
+ */
+struct mon_reader {
+	struct list_head r_link;
+	struct mon_bus *m_bus;
+	void *r_data;		/* Use container_of instead? */
+
+	void (*rnf_submit)(void *data, struct urb *urb);
+	void (*rnf_complete)(void *data, struct urb *urb);
+};
+
+void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r);
+void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r);
+
+extern struct semaphore mon_lock;
+
+extern struct file_operations mon_fops_text;
+extern struct file_operations mon_fops_stat;
+
+#endif /* __USB_MON_H */