Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1480 insertions, 0 deletions

diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
new file mode 100644
index 000000000000..40bdb38e7bcb
--- /dev/null
+++ b/drivers/usb/core/message.c
@@ -0,0 +1,1480 @@
+/*
+ * message.c - synchronous message handling
+ */
+
+#include <linux/config.h>
+
+#ifdef CONFIG_USB_DEBUG
+	#define DEBUG
+#else
+	#undef DEBUG
+#endif
+
+#include <linux/pci.h>	/* for scatterlist macros */
+#include <linux/usb.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/timer.h>
+#include <linux/ctype.h>
+#include <linux/device.h>
+#include <asm/byteorder.h>
+
+#include "hcd.h"	/* for usbcore internals */
+#include "usb.h"
+
+static void usb_api_blocking_completion(struct urb *urb, struct pt_regs *regs)
+{
+	complete((struct completion *)urb->context);
+}
+
+
+static void timeout_kill(unsigned long data)
+{
+	struct urb	*urb = (struct urb *) data;
+
+	usb_unlink_urb(urb);
+}
+
+// Starts urb and waits for completion or timeout
+// note that this call is NOT interruptible, while
+// many device driver i/o requests should be interruptible
+static int usb_start_wait_urb(struct urb *urb, int timeout, int* actual_length)
+{ 
+	struct completion	done;
+	struct timer_list	timer;
+	int			status;
+
+	init_completion(&done); 	
+	urb->context = &done;
+	urb->transfer_flags |= URB_ASYNC_UNLINK;
+	urb->actual_length = 0;
+	status = usb_submit_urb(urb, GFP_NOIO);
+
+	if (status == 0) {
+		if (timeout > 0) {
+			init_timer(&timer);
+			timer.expires = jiffies + msecs_to_jiffies(timeout);
+			timer.data = (unsigned long)urb;
+			timer.function = timeout_kill;
+			/* grr.  timeout _should_ include submit delays. */
+			add_timer(&timer);
+		}
+		wait_for_completion(&done);
+		status = urb->status;
+		/* note:  HCDs return ETIMEDOUT for other reasons too */
+		if (status == -ECONNRESET) {
+			dev_dbg(&urb->dev->dev,
+				"%s timed out on ep%d%s len=%d/%d\n",
+				current->comm,
+				usb_pipeendpoint(urb->pipe),
+				usb_pipein(urb->pipe) ? "in" : "out",
+				urb->actual_length,
+				urb->transfer_buffer_length
+				);
+			if (urb->actual_length > 0)
+				status = 0;
+			else
+				status = -ETIMEDOUT;
+		}
+		if (timeout > 0)
+			del_timer_sync(&timer);
+	}
+
+	if (actual_length)
+		*actual_length = urb->actual_length;
+	usb_free_urb(urb);
+	return status;
+}
+
+/*-------------------------------------------------------------------*/
+// returns status (negative) or length (positive)
+static int usb_internal_control_msg(struct usb_device *usb_dev,
+				    unsigned int pipe, 
+				    struct usb_ctrlrequest *cmd,
+				    void *data, int len, int timeout)
+{
+	struct urb *urb;
+	int retv;
+	int length;
+
+	urb = usb_alloc_urb(0, GFP_NOIO);
+	if (!urb)
+		return -ENOMEM;
+  
+	usb_fill_control_urb(urb, usb_dev, pipe, (unsigned char *)cmd, data,
+			     len, usb_api_blocking_completion, NULL);
+
+	retv = usb_start_wait_urb(urb, timeout, &length);
+	if (retv < 0)
+		return retv;
+	else
+		return length;
+}
+
+/**
+ *	usb_control_msg - Builds a control urb, sends it off and waits for completion
+ *	@dev: pointer to the usb device to send the message to
+ *	@pipe: endpoint "pipe" to send the message to
+ *	@request: USB message request value
+ *	@requesttype: USB message request type value
+ *	@value: USB message value
+ *	@index: USB message index value
+ *	@data: pointer to the data to send
+ *	@size: length in bytes of the data to send
+ *	@timeout: time in msecs to wait for the message to complete before
+ *		timing out (if 0 the wait is forever)
+ *	Context: !in_interrupt ()
+ *
+ *	This function sends a simple control message to a specified endpoint
+ *	and waits for the message to complete, or timeout.
+ *	
+ *	If successful, it returns the number of bytes transferred, otherwise a negative error number.
+ *
+ *	Don't use this function from within an interrupt context, like a
+ *	bottom half handler.  If you need an asynchronous message, or need to send
+ *	a message from within interrupt context, use usb_submit_urb()
+ *      If a thread in your driver uses this call, make sure your disconnect()
+ *      method can wait for it to complete.  Since you don't have a handle on
+ *      the URB used, you can't cancel the request.
+ */
+int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request, __u8 requesttype,
+			 __u16 value, __u16 index, void *data, __u16 size, int timeout)
+{
+	struct usb_ctrlrequest *dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_NOIO);
+	int ret;
+	
+	if (!dr)
+		return -ENOMEM;
+
+	dr->bRequestType= requesttype;
+	dr->bRequest = request;
+	dr->wValue = cpu_to_le16p(&value);
+	dr->wIndex = cpu_to_le16p(&index);
+	dr->wLength = cpu_to_le16p(&size);
+
+	//dbg("usb_control_msg");	
+
+	ret = usb_internal_control_msg(dev, pipe, dr, data, size, timeout);
+
+	kfree(dr);
+
+	return ret;
+}
+
+
+/**
+ *	usb_bulk_msg - Builds a bulk urb, sends it off and waits for completion
+ *	@usb_dev: pointer to the usb device to send the message to
+ *	@pipe: endpoint "pipe" to send the message to
+ *	@data: pointer to the data to send
+ *	@len: length in bytes of the data to send
+ *	@actual_length: pointer to a location to put the actual length transferred in bytes
+ *	@timeout: time in msecs to wait for the message to complete before
+ *		timing out (if 0 the wait is forever)
+ *	Context: !in_interrupt ()
+ *
+ *	This function sends a simple bulk message to a specified endpoint
+ *	and waits for the message to complete, or timeout.
+ *	
+ *	If successful, it returns 0, otherwise a negative error number.
+ *	The number of actual bytes transferred will be stored in the 
+ *	actual_length paramater.
+ *
+ *	Don't use this function from within an interrupt context, like a
+ *	bottom half handler.  If you need an asynchronous message, or need to
+ *	send a message from within interrupt context, use usb_submit_urb()
+ *      If a thread in your driver uses this call, make sure your disconnect()
+ *      method can wait for it to complete.  Since you don't have a handle on
+ *      the URB used, you can't cancel the request.
+ */
+int usb_bulk_msg(struct usb_device *usb_dev, unsigned int pipe, 
+			void *data, int len, int *actual_length, int timeout)
+{
+	struct urb *urb;
+
+	if (len < 0)
+		return -EINVAL;
+
+	urb=usb_alloc_urb(0, GFP_KERNEL);
+	if (!urb)
+		return -ENOMEM;
+
+	usb_fill_bulk_urb(urb, usb_dev, pipe, data, len,
+			  usb_api_blocking_completion, NULL);
+
+	return usb_start_wait_urb(urb, timeout, actual_length);
+}
+
+/*-------------------------------------------------------------------*/
+
+static void sg_clean (struct usb_sg_request *io)
+{
+	if (io->urbs) {
+		while (io->entries--)
+			usb_free_urb (io->urbs [io->entries]);
+		kfree (io->urbs);
+		io->urbs = NULL;
+	}
+	if (io->dev->dev.dma_mask != NULL)
+		usb_buffer_unmap_sg (io->dev, io->pipe, io->sg, io->nents);
+	io->dev = NULL;
+}
+
+static void sg_complete (struct urb *urb, struct pt_regs *regs)
+{
+	struct usb_sg_request	*io = (struct usb_sg_request *) urb->context;
+
+	spin_lock (&io->lock);
+
+	/* In 2.5 we require hcds' endpoint queues not to progress after fault
+	 * reports, until the completion callback (this!) returns.  That lets
+	 * device driver code (like this routine) unlink queued urbs first,
+	 * if it needs to, since the HC won't work on them at all.  So it's
+	 * not possible for page N+1 to overwrite page N, and so on.
+	 *
+	 * That's only for "hard" faults; "soft" faults (unlinks) sometimes
+	 * complete before the HCD can get requests away from hardware,
+	 * though never during cleanup after a hard fault.
+	 */
+	if (io->status
+			&& (io->status != -ECONNRESET
+				|| urb->status != -ECONNRESET)
+			&& urb->actual_length) {
+		dev_err (io->dev->bus->controller,
+			"dev %s ep%d%s scatterlist error %d/%d\n",
+			io->dev->devpath,
+			usb_pipeendpoint (urb->pipe),
+			usb_pipein (urb->pipe) ? "in" : "out",
+			urb->status, io->status);
+		// BUG ();
+	}
+
+	if (io->status == 0 && urb->status && urb->status != -ECONNRESET) {
+		int		i, found, status;
+
+		io->status = urb->status;
+
+		/* the previous urbs, and this one, completed already.
+		 * unlink pending urbs so they won't rx/tx bad data.
+		 * careful: unlink can sometimes be synchronous...
+		 */
+		spin_unlock (&io->lock);
+		for (i = 0, found = 0; i < io->entries; i++) {
+			if (!io->urbs [i] || !io->urbs [i]->dev)
+				continue;
+			if (found) {
+				status = usb_unlink_urb (io->urbs [i]);
+				if (status != -EINPROGRESS && status != -EBUSY)
+					dev_err (&io->dev->dev,
+						"%s, unlink --> %d\n",
+						__FUNCTION__, status);
+			} else if (urb == io->urbs [i])
+				found = 1;
+		}
+		spin_lock (&io->lock);
+	}
+	urb->dev = NULL;
+
+	/* on the last completion, signal usb_sg_wait() */
+	io->bytes += urb->actual_length;
+	io->count--;
+	if (!io->count)
+		complete (&io->complete);
+
+	spin_unlock (&io->lock);
+}
+
+
+/**
+ * usb_sg_init - initializes scatterlist-based bulk/interrupt I/O request
+ * @io: request block being initialized.  until usb_sg_wait() returns,
+ *	treat this as a pointer to an opaque block of memory,
+ * @dev: the usb device that will send or receive the data
+ * @pipe: endpoint "pipe" used to transfer the data
+ * @period: polling rate for interrupt endpoints, in frames or
+ * 	(for high speed endpoints) microframes; ignored for bulk
+ * @sg: scatterlist entries
+ * @nents: how many entries in the scatterlist
+ * @length: how many bytes to send from the scatterlist, or zero to
+ * 	send every byte identified in the list.
+ * @mem_flags: SLAB_* flags affecting memory allocations in this call
+ *
+ * Returns zero for success, else a negative errno value.  This initializes a
+ * scatter/gather request, allocating resources such as I/O mappings and urb
+ * memory (except maybe memory used by USB controller drivers).
+ *
+ * The request must be issued using usb_sg_wait(), which waits for the I/O to
+ * complete (or to be canceled) and then cleans up all resources allocated by
+ * usb_sg_init().
+ *
+ * The request may be canceled with usb_sg_cancel(), either before or after
+ * usb_sg_wait() is called.
+ */
+int usb_sg_init (
+	struct usb_sg_request	*io,
+	struct usb_device	*dev,
+	unsigned		pipe, 
+	unsigned		period,
+	struct scatterlist	*sg,
+	int			nents,
+	size_t			length,
+	int			mem_flags
+)
+{
+	int			i;
+	int			urb_flags;
+	int			dma;
+
+	if (!io || !dev || !sg
+			|| usb_pipecontrol (pipe)
+			|| usb_pipeisoc (pipe)
+			|| nents <= 0)
+		return -EINVAL;
+
+	spin_lock_init (&io->lock);
+	io->dev = dev;
+	io->pipe = pipe;
+	io->sg = sg;
+	io->nents = nents;
+
+	/* not all host controllers use DMA (like the mainstream pci ones);
+	 * they can use PIO (sl811) or be software over another transport.
+	 */
+	dma = (dev->dev.dma_mask != NULL);
+	if (dma)
+		io->entries = usb_buffer_map_sg (dev, pipe, sg, nents);
+	else
+		io->entries = nents;
+
+	/* initialize all the urbs we'll use */
+	if (io->entries <= 0)
+		return io->entries;
+
+	io->count = io->entries;
+	io->urbs = kmalloc (io->entries * sizeof *io->urbs, mem_flags);
+	if (!io->urbs)
+		goto nomem;
+
+	urb_flags = URB_ASYNC_UNLINK | URB_NO_TRANSFER_DMA_MAP
+			| URB_NO_INTERRUPT;
+	if (usb_pipein (pipe))
+		urb_flags |= URB_SHORT_NOT_OK;
+
+	for (i = 0; i < io->entries; i++) {
+		unsigned		len;
+
+		io->urbs [i] = usb_alloc_urb (0, mem_flags);
+		if (!io->urbs [i]) {
+			io->entries = i;
+			goto nomem;
+		}
+
+		io->urbs [i]->dev = NULL;
+		io->urbs [i]->pipe = pipe;
+		io->urbs [i]->interval = period;
+		io->urbs [i]->transfer_flags = urb_flags;
+
+		io->urbs [i]->complete = sg_complete;
+		io->urbs [i]->context = io;
+		io->urbs [i]->status = -EINPROGRESS;
+		io->urbs [i]->actual_length = 0;
+
+		if (dma) {
+			/* hc may use _only_ transfer_dma */
+			io->urbs [i]->transfer_dma = sg_dma_address (sg + i);
+			len = sg_dma_len (sg + i);
+		} else {
+			/* hc may use _only_ transfer_buffer */
+			io->urbs [i]->transfer_buffer =
+				page_address (sg [i].page) + sg [i].offset;
+			len = sg [i].length;
+		}
+
+		if (length) {
+			len = min_t (unsigned, len, length);
+			length -= len;
+			if (length == 0)
+				io->entries = i + 1;
+		}
+		io->urbs [i]->transfer_buffer_length = len;
+	}
+	io->urbs [--i]->transfer_flags &= ~URB_NO_INTERRUPT;
+
+	/* transaction state */
+	io->status = 0;
+	io->bytes = 0;
+	init_completion (&io->complete);
+	return 0;
+
+nomem:
+	sg_clean (io);
+	return -ENOMEM;
+}
+
+
+/**
+ * usb_sg_wait - synchronously execute scatter/gather request
+ * @io: request block handle, as initialized with usb_sg_init().
+ * 	some fields become accessible when this call returns.
+ * Context: !in_interrupt ()
+ *
+ * This function blocks until the specified I/O operation completes.  It
+ * leverages the grouping of the related I/O requests to get good transfer
+ * rates, by queueing the requests.  At higher speeds, such queuing can
+ * significantly improve USB throughput.
+ *
+ * There are three kinds of completion for this function.
+ * (1) success, where io->status is zero.  The number of io->bytes
+ *     transferred is as requested.
+ * (2) error, where io->status is a negative errno value.  The number
+ *     of io->bytes transferred before the error is usually less
+ *     than requested, and can be nonzero.
+ * (3) cancelation, a type of error with status -ECONNRESET that
+ *     is initiated by usb_sg_cancel().
+ *
+ * When this function returns, all memory allocated through usb_sg_init() or
+ * this call will have been freed.  The request block parameter may still be
+ * passed to usb_sg_cancel(), or it may be freed.  It could also be
+ * reinitialized and then reused.
+ *
+ * Data Transfer Rates:
+ *
+ * Bulk transfers are valid for full or high speed endpoints.
+ * The best full speed data rate is 19 packets of 64 bytes each
+ * per frame, or 1216 bytes per millisecond.
+ * The best high speed data rate is 13 packets of 512 bytes each
+ * per microframe, or 52 KBytes per millisecond.
+ *
+ * The reason to use interrupt transfers through this API would most likely
+ * be to reserve high speed bandwidth, where up to 24 KBytes per millisecond
+ * could be transferred.  That capability is less useful for low or full
+ * speed interrupt endpoints, which allow at most one packet per millisecond,
+ * of at most 8 or 64 bytes (respectively).
+ */
+void usb_sg_wait (struct usb_sg_request *io)
+{
+	int		i, entries = io->entries;
+
+	/* queue the urbs.  */
+	spin_lock_irq (&io->lock);
+	for (i = 0; i < entries && !io->status; i++) {
+		int	retval;
+
+		io->urbs [i]->dev = io->dev;
+		retval = usb_submit_urb (io->urbs [i], SLAB_ATOMIC);
+
+		/* after we submit, let completions or cancelations fire;
+		 * we handshake using io->status.
+		 */
+		spin_unlock_irq (&io->lock);
+		switch (retval) {
+			/* maybe we retrying will recover */
+		case -ENXIO:	// hc didn't queue this one
+		case -EAGAIN:
+		case -ENOMEM:
+			io->urbs[i]->dev = NULL;
+			retval = 0;
+			i--;
+			yield ();
+			break;
+
+			/* no error? continue immediately.
+			 *
+			 * NOTE: to work better with UHCI (4K I/O buffer may
+			 * need 3K of TDs) it may be good to limit how many
+			 * URBs are queued at once; N milliseconds?
+			 */
+		case 0:
+			cpu_relax ();
+			break;
+
+			/* fail any uncompleted urbs */
+		default:
+			io->urbs [i]->dev = NULL;
+			io->urbs [i]->status = retval;
+			dev_dbg (&io->dev->dev, "%s, submit --> %d\n",
+				__FUNCTION__, retval);
+			usb_sg_cancel (io);
+		}
+		spin_lock_irq (&io->lock);
+		if (retval && (io->status == 0 || io->status == -ECONNRESET))
+			io->status = retval;
+	}
+	io->count -= entries - i;
+	if (io->count == 0)
+		complete (&io->complete);
+	spin_unlock_irq (&io->lock);
+
+	/* OK, yes, this could be packaged as non-blocking.
+	 * So could the submit loop above ... but it's easier to
+	 * solve neither problem than to solve both!
+	 */
+	wait_for_completion (&io->complete);
+
+	sg_clean (io);
+}
+
+/**
+ * usb_sg_cancel - stop scatter/gather i/o issued by usb_sg_wait()
+ * @io: request block, initialized with usb_sg_init()
+ *
+ * This stops a request after it has been started by usb_sg_wait().
+ * It can also prevents one initialized by usb_sg_init() from starting,
+ * so that call just frees resources allocated to the request.
+ */
+void usb_sg_cancel (struct usb_sg_request *io)
+{
+	unsigned long	flags;
+
+	spin_lock_irqsave (&io->lock, flags);
+
+	/* shut everything down, if it didn't already */
+	if (!io->status) {
+		int	i;
+
+		io->status = -ECONNRESET;
+		spin_unlock (&io->lock);
+		for (i = 0; i < io->entries; i++) {
+			int	retval;
+
+			if (!io->urbs [i]->dev)
+				continue;
+			retval = usb_unlink_urb (io->urbs [i]);
+			if (retval != -EINPROGRESS && retval != -EBUSY)
+				dev_warn (&io->dev->dev, "%s, unlink --> %d\n",
+					__FUNCTION__, retval);
+		}
+		spin_lock (&io->lock);
+	}
+	spin_unlock_irqrestore (&io->lock, flags);
+}
+
+/*-------------------------------------------------------------------*/
+
+/**
+ * usb_get_descriptor - issues a generic GET_DESCRIPTOR request
+ * @dev: the device whose descriptor is being retrieved
+ * @type: the descriptor type (USB_DT_*)
+ * @index: the number of the descriptor
+ * @buf: where to put the descriptor
+ * @size: how big is "buf"?
+ * Context: !in_interrupt ()
+ *
+ * Gets a USB descriptor.  Convenience functions exist to simplify
+ * getting some types of descriptors.  Use
+ * usb_get_string() or usb_string() for USB_DT_STRING.
+ * Device (USB_DT_DEVICE) and configuration descriptors (USB_DT_CONFIG)
+ * are part of the device structure.
+ * In addition to a number of USB-standard descriptors, some
+ * devices also use class-specific or vendor-specific descriptors.
+ *
+ * This call is synchronous, and may not be used in an interrupt context.
+ *
+ * Returns the number of bytes received on success, or else the status code
+ * returned by the underlying usb_control_msg() call.
+ */
+int usb_get_descriptor(struct usb_device *dev, unsigned char type, unsigned char index, void *buf, int size)
+{
+	int i;
+	int result;
+	
+	memset(buf,0,size);	// Make sure we parse really received data
+
+	for (i = 0; i < 3; ++i) {
+		/* retry on length 0 or stall; some devices are flakey */
+		result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
+				USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
+				(type << 8) + index, 0, buf, size,
+				USB_CTRL_GET_TIMEOUT);
+		if (result == 0 || result == -EPIPE)
+			continue;
+		if (result > 1 && ((u8 *)buf)[1] != type) {
+			result = -EPROTO;
+			continue;
+		}
+		break;
+	}
+	return result;
+}
+
+/**
+ * usb_get_string - gets a string descriptor
+ * @dev: the device whose string descriptor is being retrieved
+ * @langid: code for language chosen (from string descriptor zero)
+ * @index: the number of the descriptor
+ * @buf: where to put the string
+ * @size: how big is "buf"?
+ * Context: !in_interrupt ()
+ *
+ * Retrieves a string, encoded using UTF-16LE (Unicode, 16 bits per character,
+ * in little-endian byte order).
+ * The usb_string() function will often be a convenient way to turn
+ * these strings into kernel-printable form.
+ *
+ * Strings may be referenced in device, configuration, interface, or other
+ * descriptors, and could also be used in vendor-specific ways.
+ *
+ * This call is synchronous, and may not be used in an interrupt context.
+ *
+ * Returns the number of bytes received on success, or else the status code
+ * returned by the underlying usb_control_msg() call.
+ */
+int usb_get_string(struct usb_device *dev, unsigned short langid,
+		unsigned char index, void *buf, int size)
+{
+	int i;
+	int result;
+
+	for (i = 0; i < 3; ++i) {
+		/* retry on length 0 or stall; some devices are flakey */
+		result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
+			USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
+			(USB_DT_STRING << 8) + index, langid, buf, size,
+			USB_CTRL_GET_TIMEOUT);
+		if (!(result == 0 || result == -EPIPE))
+			break;
+	}
+	return result;
+}
+
+static void usb_try_string_workarounds(unsigned char *buf, int *length)
+{
+	int newlength, oldlength = *length;
+
+	for (newlength = 2; newlength + 1 < oldlength; newlength += 2)
+		if (!isprint(buf[newlength]) || buf[newlength + 1])
+			break;
+
+	if (newlength > 2) {
+		buf[0] = newlength;
+		*length = newlength;
+	}
+}
+
+static int usb_string_sub(struct usb_device *dev, unsigned int langid,
+		unsigned int index, unsigned char *buf)
+{
+	int rc;
+
+	/* Try to read the string descriptor by asking for the maximum
+	 * possible number of bytes */
+	rc = usb_get_string(dev, langid, index, buf, 255);
+
+	/* If that failed try to read the descriptor length, then
+	 * ask for just that many bytes */
+	if (rc < 2) {
+		rc = usb_get_string(dev, langid, index, buf, 2);
+		if (rc == 2)
+			rc = usb_get_string(dev, langid, index, buf, buf[0]);
+	}
+
+	if (rc >= 2) {
+		if (!buf[0] && !buf[1])
+			usb_try_string_workarounds(buf, &rc);
+
+		/* There might be extra junk at the end of the descriptor */
+		if (buf[0] < rc)
+			rc = buf[0];
+
+		rc = rc - (rc & 1); /* force a multiple of two */
+	}
+
+	if (rc < 2)
+		rc = (rc < 0 ? rc : -EINVAL);
+
+	return rc;
+}
+
+/**
+ * usb_string - returns ISO 8859-1 version of a string descriptor
+ * @dev: the device whose string descriptor is being retrieved
+ * @index: the number of the descriptor
+ * @buf: where to put the string
+ * @size: how big is "buf"?
+ * Context: !in_interrupt ()
+ * 
+ * This converts the UTF-16LE encoded strings returned by devices, from
+ * usb_get_string_descriptor(), to null-terminated ISO-8859-1 encoded ones
+ * that are more usable in most kernel contexts.  Note that all characters
+ * in the chosen descriptor that can't be encoded using ISO-8859-1
+ * are converted to the question mark ("?") character, and this function
+ * chooses strings in the first language supported by the device.
+ *
+ * The ASCII (or, redundantly, "US-ASCII") character set is the seven-bit
+ * subset of ISO 8859-1. ISO-8859-1 is the eight-bit subset of Unicode,
+ * and is appropriate for use many uses of English and several other
+ * Western European languages.  (But it doesn't include the "Euro" symbol.)
+ *
+ * This call is synchronous, and may not be used in an interrupt context.
+ *
+ * Returns length of the string (>= 0) or usb_control_msg status (< 0).
+ */
+int usb_string(struct usb_device *dev, int index, char *buf, size_t size)
+{
+	unsigned char *tbuf;
+	int err;
+	unsigned int u, idx;
+
+	if (dev->state == USB_STATE_SUSPENDED)
+		return -EHOSTUNREACH;
+	if (size <= 0 || !buf || !index)
+		return -EINVAL;
+	buf[0] = 0;
+	tbuf = kmalloc(256, GFP_KERNEL);
+	if (!tbuf)
+		return -ENOMEM;
+
+	/* get langid for strings if it's not yet known */
+	if (!dev->have_langid) {
+		err = usb_string_sub(dev, 0, 0, tbuf);
+		if (err < 0) {
+			dev_err (&dev->dev,
+				"string descriptor 0 read error: %d\n",
+				err);
+			goto errout;
+		} else if (err < 4) {
+			dev_err (&dev->dev, "string descriptor 0 too short\n");
+			err = -EINVAL;
+			goto errout;
+		} else {
+			dev->have_langid = -1;
+			dev->string_langid = tbuf[2] | (tbuf[3]<< 8);
+				/* always use the first langid listed */
+			dev_dbg (&dev->dev, "default language 0x%04x\n",
+				dev->string_langid);
+		}
+	}
+	
+	err = usb_string_sub(dev, dev->string_langid, index, tbuf);
+	if (err < 0)
+		goto errout;
+
+	size--;		/* leave room for trailing NULL char in output buffer */
+	for (idx = 0, u = 2; u < err; u += 2) {
+		if (idx >= size)
+			break;
+		if (tbuf[u+1])			/* high byte */
+			buf[idx++] = '?';  /* non ISO-8859-1 character */
+		else
+			buf[idx++] = tbuf[u];
+	}
+	buf[idx] = 0;
+	err = idx;
+
+	if (tbuf[1] != USB_DT_STRING)
+		dev_dbg(&dev->dev, "wrong descriptor type %02x for string %d (\"%s\")\n", tbuf[1], index, buf);
+
+ errout:
+	kfree(tbuf);
+	return err;
+}
+
+/*
+ * usb_get_device_descriptor - (re)reads the device descriptor (usbcore)
+ * @dev: the device whose device descriptor is being updated
+ * @size: how much of the descriptor to read
+ * Context: !in_interrupt ()
+ *
+ * Updates the copy of the device descriptor stored in the device structure,
+ * which dedicates space for this purpose.  Note that several fields are
+ * converted to the host CPU's byte order:  the USB version (bcdUSB), and
+ * vendors product and version fields (idVendor, idProduct, and bcdDevice).
+ * That lets device drivers compare against non-byteswapped constants.
+ *
+ * Not exported, only for use by the core.  If drivers really want to read
+ * the device descriptor directly, they can call usb_get_descriptor() with
+ * type = USB_DT_DEVICE and index = 0.
+ *
+ * This call is synchronous, and may not be used in an interrupt context.
+ *
+ * Returns the number of bytes received on success, or else the status code
+ * returned by the underlying usb_control_msg() call.
+ */
+int usb_get_device_descriptor(struct usb_device *dev, unsigned int size)
+{
+	struct usb_device_descriptor *desc;
+	int ret;
+
+	if (size > sizeof(*desc))
+		return -EINVAL;
+	desc = kmalloc(sizeof(*desc), GFP_NOIO);
+	if (!desc)
+		return -ENOMEM;
+
+	ret = usb_get_descriptor(dev, USB_DT_DEVICE, 0, desc, size);
+	if (ret >= 0) 
+		memcpy(&dev->descriptor, desc, size);
+	kfree(desc);
+	return ret;
+}
+
+/**
+ * usb_get_status - issues a GET_STATUS call
+ * @dev: the device whose status is being checked
+ * @type: USB_RECIP_*; for device, interface, or endpoint
+ * @target: zero (for device), else interface or endpoint number
+ * @data: pointer to two bytes of bitmap data
+ * Context: !in_interrupt ()
+ *
+ * Returns device, interface, or endpoint status.  Normally only of
+ * interest to see if the device is self powered, or has enabled the
+ * remote wakeup facility; or whether a bulk or interrupt endpoint
+ * is halted ("stalled").
+ *
+ * Bits in these status bitmaps are set using the SET_FEATURE request,
+ * and cleared using the CLEAR_FEATURE request.  The usb_clear_halt()
+ * function should be used to clear halt ("stall") status.
+ *
+ * This call is synchronous, and may not be used in an interrupt context.
+ *
+ * Returns the number of bytes received on success, or else the status code
+ * returned by the underlying usb_control_msg() call.
+ */
+int usb_get_status(struct usb_device *dev, int type, int target, void *data)
+{
+	int ret;
+	u16 *status = kmalloc(sizeof(*status), GFP_KERNEL);
+
+	if (!status)
+		return -ENOMEM;
+
+	ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
+		USB_REQ_GET_STATUS, USB_DIR_IN | type, 0, target, status,
+		sizeof(*status), USB_CTRL_GET_TIMEOUT);
+
+	*(u16 *)data = *status;
+	kfree(status);
+	return ret;
+}
+
+/**
+ * usb_clear_halt - tells device to clear endpoint halt/stall condition
+ * @dev: device whose endpoint is halted
+ * @pipe: endpoint "pipe" being cleared
+ * Context: !in_interrupt ()
+ *
+ * This is used to clear halt conditions for bulk and interrupt endpoints,
+ * as reported by URB completion status.  Endpoints that are halted are
+ * sometimes referred to as being "stalled".  Such endpoints are unable
+ * to transmit or receive data until the halt status is cleared.  Any URBs
+ * queued for such an endpoint should normally be unlinked by the driver
+ * before clearing the halt condition, as described in sections 5.7.5
+ * and 5.8.5 of the USB 2.0 spec.
+ *
+ * Note that control and isochronous endpoints don't halt, although control
+ * endpoints report "protocol stall" (for unsupported requests) using the
+ * same status code used to report a true stall.
+ *
+ * This call is synchronous, and may not be used in an interrupt context.
+ *
+ * Returns zero on success, or else the status code returned by the
+ * underlying usb_control_msg() call.
+ */
+int usb_clear_halt(struct usb_device *dev, int pipe)
+{
+	int result;
+	int endp = usb_pipeendpoint(pipe);
+	
+	if (usb_pipein (pipe))
+		endp |= USB_DIR_IN;
+
+	/* we don't care if it wasn't halted first. in fact some devices
+	 * (like some ibmcam model 1 units) seem to expect hosts to make
+	 * this request for iso endpoints, which can't halt!
+	 */
+	result = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
+		USB_REQ_CLEAR_FEATURE, USB_RECIP_ENDPOINT,
+		USB_ENDPOINT_HALT, endp, NULL, 0,
+		USB_CTRL_SET_TIMEOUT);
+
+	/* don't un-halt or force to DATA0 except on success */
+	if (result < 0)
+		return result;
+
+	/* NOTE:  seems like Microsoft and Apple don't bother verifying
+	 * the clear "took", so some devices could lock up if you check...
+	 * such as the Hagiwara FlashGate DUAL.  So we won't bother.
+	 *
+	 * NOTE:  make sure the logic here doesn't diverge much from
+	 * the copy in usb-storage, for as long as we need two copies.
+	 */
+
+	/* toggle was reset by the clear */
+	usb_settoggle(dev, usb_pipeendpoint(pipe), usb_pipeout(pipe), 0);
+
+	return 0;
+}
+
+/**
+ * usb_disable_endpoint -- Disable an endpoint by address
+ * @dev: the device whose endpoint is being disabled
+ * @epaddr: the endpoint's address.  Endpoint number for output,
+ *	endpoint number + USB_DIR_IN for input
+ *
+ * Deallocates hcd/hardware state for this endpoint ... and nukes all
+ * pending urbs.
+ *
+ * If the HCD hasn't registered a disable() function, this sets the
+ * endpoint's maxpacket size to 0 to prevent further submissions.
+ */
+void usb_disable_endpoint(struct usb_device *dev, unsigned int epaddr)
+{
+	unsigned int epnum = epaddr & USB_ENDPOINT_NUMBER_MASK;
+	struct usb_host_endpoint *ep;
+
+	if (!dev)
+		return;
+
+	if (usb_endpoint_out(epaddr)) {
+		ep = dev->ep_out[epnum];
+		dev->ep_out[epnum] = NULL;
+	} else {
+		ep = dev->ep_in[epnum];
+		dev->ep_in[epnum] = NULL;
+	}
+	if (ep && dev->bus && dev->bus->op && dev->bus->op->disable)
+		dev->bus->op->disable(dev, ep);
+}
+
+/**
+ * usb_disable_interface -- Disable all endpoints for an interface
+ * @dev: the device whose interface is being disabled
+ * @intf: pointer to the interface descriptor
+ *
+ * Disables all the endpoints for the interface's current altsetting.
+ */
+void usb_disable_interface(struct usb_device *dev, struct usb_interface *intf)
+{
+	struct usb_host_interface *alt = intf->cur_altsetting;
+	int i;
+
+	for (i = 0; i < alt->desc.bNumEndpoints; ++i) {
+		usb_disable_endpoint(dev,
+				alt->endpoint[i].desc.bEndpointAddress);
+	}
+}
+
+/*
+ * usb_disable_device - Disable all the endpoints for a USB device
+ * @dev: the device whose endpoints are being disabled
+ * @skip_ep0: 0 to disable endpoint 0, 1 to skip it.
+ *
+ * Disables all the device's endpoints, potentially including endpoint 0.
+ * Deallocates hcd/hardware state for the endpoints (nuking all or most
+ * pending urbs) and usbcore state for the interfaces, so that usbcore
+ * must usb_set_configuration() before any interfaces could be used.
+ */
+void usb_disable_device(struct usb_device *dev, int skip_ep0)
+{
+	int i;
+
+	dev_dbg(&dev->dev, "%s nuking %s URBs\n", __FUNCTION__,
+			skip_ep0 ? "non-ep0" : "all");
+	for (i = skip_ep0; i < 16; ++i) {
+		usb_disable_endpoint(dev, i);
+		usb_disable_endpoint(dev, i + USB_DIR_IN);
+	}
+	dev->toggle[0] = dev->toggle[1] = 0;
+
+	/* getting rid of interfaces will disconnect
+	 * any drivers bound to them (a key side effect)
+	 */
+	if (dev->actconfig) {
+		for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++) {
+			struct usb_interface	*interface;
+
+			/* remove this interface */
+			interface = dev->actconfig->interface[i];
+			dev_dbg (&dev->dev, "unregistering interface %s\n",
+				interface->dev.bus_id);
+			usb_remove_sysfs_intf_files(interface);
+			kfree(interface->cur_altsetting->string);
+			interface->cur_altsetting->string = NULL;
+			device_del (&interface->dev);
+		}
+
+		/* Now that the interfaces are unbound, nobody should
+		 * try to access them.
+		 */
+		for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++) {
+			put_device (&dev->actconfig->interface[i]->dev);
+			dev->actconfig->interface[i] = NULL;
+		}
+		dev->actconfig = NULL;
+		if (dev->state == USB_STATE_CONFIGURED)
+			usb_set_device_state(dev, USB_STATE_ADDRESS);
+	}
+}
+
+
+/*
+ * usb_enable_endpoint - Enable an endpoint for USB communications
+ * @dev: the device whose interface is being enabled
+ * @ep: the endpoint
+ *
+ * Resets the endpoint toggle, and sets dev->ep_{in,out} pointers.
+ * For control endpoints, both the input and output sides are handled.
+ */
+static void
+usb_enable_endpoint(struct usb_device *dev, struct usb_host_endpoint *ep)
+{
+	unsigned int epaddr = ep->desc.bEndpointAddress;
+	unsigned int epnum = epaddr & USB_ENDPOINT_NUMBER_MASK;
+	int is_control;
+
+	is_control = ((ep->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
+			== USB_ENDPOINT_XFER_CONTROL);
+	if (usb_endpoint_out(epaddr) || is_control) {
+		usb_settoggle(dev, epnum, 1, 0);
+		dev->ep_out[epnum] = ep;
+	}
+	if (!usb_endpoint_out(epaddr) || is_control) {
+		usb_settoggle(dev, epnum, 0, 0);
+		dev->ep_in[epnum] = ep;
+	}
+}
+
+/*
+ * usb_enable_interface - Enable all the endpoints for an interface
+ * @dev: the device whose interface is being enabled
+ * @intf: pointer to the interface descriptor
+ *
+ * Enables all the endpoints for the interface's current altsetting.
+ */
+static void usb_enable_interface(struct usb_device *dev,
+				 struct usb_interface *intf)
+{
+	struct usb_host_interface *alt = intf->cur_altsetting;
+	int i;
+
+	for (i = 0; i < alt->desc.bNumEndpoints; ++i)
+		usb_enable_endpoint(dev, &alt->endpoint[i]);
+}
+
+/**
+ * usb_set_interface - Makes a particular alternate setting be current
+ * @dev: the device whose interface is being updated
+ * @interface: the interface being updated
+ * @alternate: the setting being chosen.
+ * Context: !in_interrupt ()
+ *
+ * This is used to enable data transfers on interfaces that may not
+ * be enabled by default.  Not all devices support such configurability.
+ * Only the driver bound to an interface may change its setting.
+ *
+ * Within any given configuration, each interface may have several
+ * alternative settings.  These are often used to control levels of
+ * bandwidth consumption.  For example, the default setting for a high
+ * speed interrupt endpoint may not send more than 64 bytes per microframe,
+ * while interrupt transfers of up to 3KBytes per microframe are legal.
+ * Also, isochronous endpoints may never be part of an
+ * interface's default setting.  To access such bandwidth, alternate
+ * interface settings must be made current.
+ *
+ * Note that in the Linux USB subsystem, bandwidth associated with
+ * an endpoint in a given alternate setting is not reserved until an URB
+ * is submitted that needs that bandwidth.  Some other operating systems
+ * allocate bandwidth early, when a configuration is chosen.
+ *
+ * This call is synchronous, and may not be used in an interrupt context.
+ * Also, drivers must not change altsettings while urbs are scheduled for
+ * endpoints in that interface; all such urbs must first be completed
+ * (perhaps forced by unlinking).
+ *
+ * Returns zero on success, or else the status code returned by the
+ * underlying usb_control_msg() call.
+ */
+int usb_set_interface(struct usb_device *dev, int interface, int alternate)
+{
+	struct usb_interface *iface;
+	struct usb_host_interface *alt;
+	int ret;
+	int manual = 0;
+
+	if (dev->state == USB_STATE_SUSPENDED)
+		return -EHOSTUNREACH;
+
+	iface = usb_ifnum_to_if(dev, interface);
+	if (!iface) {
+		dev_dbg(&dev->dev, "selecting invalid interface %d\n",
+			interface);
+		return -EINVAL;
+	}
+
+	alt = usb_altnum_to_altsetting(iface, alternate);
+	if (!alt) {
+		warn("selecting invalid altsetting %d", alternate);
+		return -EINVAL;
+	}
+
+	ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
+				   USB_REQ_SET_INTERFACE, USB_RECIP_INTERFACE,
+				   alternate, interface, NULL, 0, 5000);
+
+	/* 9.4.10 says devices don't need this and are free to STALL the
+	 * request if the interface only has one alternate setting.
+	 */
+	if (ret == -EPIPE && iface->num_altsetting == 1) {
+		dev_dbg(&dev->dev,
+			"manual set_interface for iface %d, alt %d\n",
+			interface, alternate);
+		manual = 1;
+	} else if (ret < 0)
+		return ret;
+
+	/* FIXME drivers shouldn't need to replicate/bugfix the logic here
+	 * when they implement async or easily-killable versions of this or
+	 * other "should-be-internal" functions (like clear_halt).
+	 * should hcd+usbcore postprocess control requests?
+	 */
+
+	/* prevent submissions using previous endpoint settings */
+	usb_disable_interface(dev, iface);
+
+	/* 9.1.1.5 says:
+	 *
+	 *	Configuring a device or changing an alternate setting
+	 *	causes all of the status and configuration values
+	 *	associated with endpoints in the affected interfaces to
+	 *	be set to their default values. This includes setting
+	 *	the data toggle of any endpoint using data toggles to
+	 *	the value DATA0.
+	 *
+	 * Some devices take this too literally and don't reset the data
+	 * toggles if the new altsetting is the same as the old one (the
+	 * command isn't "changing" an alternate setting).  We will manually
+	 * reset the toggles when the new and old altsettings are the same.
+	 * Most devices won't need this, but fortunately it doesn't happen
+	 * often.
+	 */
+	if (iface->cur_altsetting == alt)
+		manual = 1;
+	iface->cur_altsetting = alt;
+
+	/* If the interface only has one altsetting and the device didn't
+	 * accept the request (or whenever the old altsetting is the same
+	 * as the new one), we attempt to carry out the equivalent action
+	 * by manually clearing the HALT feature for each endpoint in the
+	 * new altsetting.
+	 */
+	if (manual) {
+		int i;
+
+		for (i = 0; i < alt->desc.bNumEndpoints; i++) {
+			unsigned int epaddr =
+				alt->endpoint[i].desc.bEndpointAddress;
+			unsigned int pipe =
+	__create_pipe(dev, USB_ENDPOINT_NUMBER_MASK & epaddr)
+	| (usb_endpoint_out(epaddr) ? USB_DIR_OUT : USB_DIR_IN);
+
+			usb_clear_halt(dev, pipe);
+		}
+	}
+
+	/* 9.1.1.5: reset toggles for all endpoints in the new altsetting
+	 *
+	 * Note:
+	 * Despite EP0 is always present in all interfaces/AS, the list of
+	 * endpoints from the descriptor does not contain EP0. Due to its
+	 * omnipresence one might expect EP0 being considered "affected" by
+	 * any SetInterface request and hence assume toggles need to be reset.
+	 * However, EP0 toggles are re-synced for every individual transfer
+	 * during the SETUP stage - hence EP0 toggles are "don't care" here.
+	 * (Likewise, EP0 never "halts" on well designed devices.)
+	 */
+	usb_enable_interface(dev, iface);
+
+	return 0;
+}
+
+/**
+ * usb_reset_configuration - lightweight device reset
+ * @dev: the device whose configuration is being reset
+ *
+ * This issues a standard SET_CONFIGURATION request to the device using
+ * the current configuration.  The effect is to reset most USB-related
+ * state in the device, including interface altsettings (reset to zero),
+ * endpoint halts (cleared), and data toggle (only for bulk and interrupt
+ * endpoints).  Other usbcore state is unchanged, including bindings of
+ * usb device drivers to interfaces.
+ *
+ * Because this affects multiple interfaces, avoid using this with composite
+ * (multi-interface) devices.  Instead, the driver for each interface may
+ * use usb_set_interface() on the interfaces it claims.  Resetting the whole
+ * configuration would affect other drivers' interfaces.
+ *
+ * The caller must own the device lock.
+ *
+ * Returns zero on success, else a negative error code.
+ */
+int usb_reset_configuration(struct usb_device *dev)
+{
+	int			i, retval;
+	struct usb_host_config	*config;
+
+	if (dev->state == USB_STATE_SUSPENDED)
+		return -EHOSTUNREACH;
+
+	/* caller must have locked the device and must own
+	 * the usb bus readlock (so driver bindings are stable);
+	 * calls during probe() are fine
+	 */
+
+	for (i = 1; i < 16; ++i) {
+		usb_disable_endpoint(dev, i);
+		usb_disable_endpoint(dev, i + USB_DIR_IN);
+	}
+
+	config = dev->actconfig;
+	retval = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
+			USB_REQ_SET_CONFIGURATION, 0,
+			config->desc.bConfigurationValue, 0,
+			NULL, 0, USB_CTRL_SET_TIMEOUT);
+	if (retval < 0) {
+		usb_set_device_state(dev, USB_STATE_ADDRESS);
+		return retval;
+	}
+
+	dev->toggle[0] = dev->toggle[1] = 0;
+
+	/* re-init hc/hcd interface/endpoint state */
+	for (i = 0; i < config->desc.bNumInterfaces; i++) {
+		struct usb_interface *intf = config->interface[i];
+		struct usb_host_interface *alt;
+
+		alt = usb_altnum_to_altsetting(intf, 0);
+
+		/* No altsetting 0?  We'll assume the first altsetting.
+		 * We could use a GetInterface call, but if a device is
+		 * so non-compliant that it doesn't have altsetting 0
+		 * then I wouldn't trust its reply anyway.
+		 */
+		if (!alt)
+			alt = &intf->altsetting[0];
+
+		intf->cur_altsetting = alt;
+		usb_enable_interface(dev, intf);
+	}
+	return 0;
+}
+
+static void release_interface(struct device *dev)
+{
+	struct usb_interface *intf = to_usb_interface(dev);
+	struct usb_interface_cache *intfc =
+			altsetting_to_usb_interface_cache(intf->altsetting);
+
+	kref_put(&intfc->ref, usb_release_interface_cache);
+	kfree(intf);
+}
+
+/*
+ * usb_set_configuration - Makes a particular device setting be current
+ * @dev: the device whose configuration is being updated
+ * @configuration: the configuration being chosen.
+ * Context: !in_interrupt(), caller owns the device lock
+ *
+ * This is used to enable non-default device modes.  Not all devices
+ * use this kind of configurability; many devices only have one
+ * configuration.
+ *
+ * USB device configurations may affect Linux interoperability,
+ * power consumption and the functionality available.  For example,
+ * the default configuration is limited to using 100mA of bus power,
+ * so that when certain device functionality requires more power,
+ * and the device is bus powered, that functionality should be in some
+ * non-default device configuration.  Other device modes may also be
+ * reflected as configuration options, such as whether two ISDN
+ * channels are available independently; and choosing between open
+ * standard device protocols (like CDC) or proprietary ones.
+ *
+ * Note that USB has an additional level of device configurability,
+ * associated with interfaces.  That configurability is accessed using
+ * usb_set_interface().
+ *
+ * This call is synchronous. The calling context must be able to sleep,
+ * must own the device lock, and must not hold the driver model's USB
+ * bus rwsem; usb device driver probe() methods cannot use this routine.
+ *
+ * Returns zero on success, or else the status code returned by the
+ * underlying call that failed.  On succesful completion, each interface
+ * in the original device configuration has been destroyed, and each one
+ * in the new configuration has been probed by all relevant usb device
+ * drivers currently known to the kernel.
+ */
+int usb_set_configuration(struct usb_device *dev, int configuration)
+{
+	int i, ret;
+	struct usb_host_config *cp = NULL;
+	struct usb_interface **new_interfaces = NULL;
+	int n, nintf;
+
+	for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
+		if (dev->config[i].desc.bConfigurationValue == configuration) {
+			cp = &dev->config[i];
+			break;
+		}
+	}
+	if ((!cp && configuration != 0))
+		return -EINVAL;
+
+	/* The USB spec says configuration 0 means unconfigured.
+	 * But if a device includes a configuration numbered 0,
+	 * we will accept it as a correctly configured state.
+	 */
+	if (cp && configuration == 0)
+		dev_warn(&dev->dev, "config 0 descriptor??\n");
+
+	if (dev->state == USB_STATE_SUSPENDED)
+		return -EHOSTUNREACH;
+
+	/* Allocate memory for new interfaces before doing anything else,
+	 * so that if we run out then nothing will have changed. */
+	n = nintf = 0;
+	if (cp) {
+		nintf = cp->desc.bNumInterfaces;
+		new_interfaces = kmalloc(nintf * sizeof(*new_interfaces),
+				GFP_KERNEL);
+		if (!new_interfaces) {
+			dev_err(&dev->dev, "Out of memory");
+			return -ENOMEM;
+		}
+
+		for (; n < nintf; ++n) {
+			new_interfaces[n] = kmalloc(
+					sizeof(struct usb_interface),
+					GFP_KERNEL);
+			if (!new_interfaces[n]) {
+				dev_err(&dev->dev, "Out of memory");
+				ret = -ENOMEM;
+free_interfaces:
+				while (--n >= 0)
+					kfree(new_interfaces[n]);
+				kfree(new_interfaces);
+				return ret;
+			}
+		}
+	}
+
+	/* if it's already configured, clear out old state first.
+	 * getting rid of old interfaces means unbinding their drivers.
+	 */
+	if (dev->state != USB_STATE_ADDRESS)
+		usb_disable_device (dev, 1);	// Skip ep0
+
+	if ((ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
+			USB_REQ_SET_CONFIGURATION, 0, configuration, 0,
+			NULL, 0, USB_CTRL_SET_TIMEOUT)) < 0)
+		goto free_interfaces;
+
+	dev->actconfig = cp;
+	if (!cp)
+		usb_set_device_state(dev, USB_STATE_ADDRESS);
+	else {
+		usb_set_device_state(dev, USB_STATE_CONFIGURED);
+
+		/* Initialize the new interface structures and the
+		 * hc/hcd/usbcore interface/endpoint state.
+		 */
+		for (i = 0; i < nintf; ++i) {
+			struct usb_interface_cache *intfc;
+			struct usb_interface *intf;
+			struct usb_host_interface *alt;
+
+			cp->interface[i] = intf = new_interfaces[i];
+			memset(intf, 0, sizeof(*intf));
+			intfc = cp->intf_cache[i];
+			intf->altsetting = intfc->altsetting;
+			intf->num_altsetting = intfc->num_altsetting;
+			kref_get(&intfc->ref);
+
+			alt = usb_altnum_to_altsetting(intf, 0);
+
+			/* No altsetting 0?  We'll assume the first altsetting.
+			 * We could use a GetInterface call, but if a device is
+			 * so non-compliant that it doesn't have altsetting 0
+			 * then I wouldn't trust its reply anyway.
+			 */
+			if (!alt)
+				alt = &intf->altsetting[0];
+
+			intf->cur_altsetting = alt;
+			usb_enable_interface(dev, intf);
+			intf->dev.parent = &dev->dev;
+			intf->dev.driver = NULL;
+			intf->dev.bus = &usb_bus_type;
+			intf->dev.dma_mask = dev->dev.dma_mask;
+			intf->dev.release = release_interface;
+			device_initialize (&intf->dev);
+			sprintf (&intf->dev.bus_id[0], "%d-%s:%d.%d",
+				 dev->bus->busnum, dev->devpath,
+				 configuration,
+				 alt->desc.bInterfaceNumber);
+		}
+		kfree(new_interfaces);
+
+		if ((cp->desc.iConfiguration) &&
+		    (cp->string == NULL)) {
+			cp->string = kmalloc(256, GFP_KERNEL);
+			if (cp->string)
+				usb_string(dev, cp->desc.iConfiguration, cp->string, 256);
+		}
+
+		/* Now that all the interfaces are set up, register them
+		 * to trigger binding of drivers to interfaces.  probe()
+		 * routines may install different altsettings and may
+		 * claim() any interfaces not yet bound.  Many class drivers
+		 * need that: CDC, audio, video, etc.
+		 */
+		for (i = 0; i < nintf; ++i) {
+			struct usb_interface *intf = cp->interface[i];
+			struct usb_interface_descriptor *desc;
+
+			desc = &intf->altsetting [0].desc;
+			dev_dbg (&dev->dev,
+				"adding %s (config #%d, interface %d)\n",
+				intf->dev.bus_id, configuration,
+				desc->bInterfaceNumber);
+			ret = device_add (&intf->dev);
+			if (ret != 0) {
+				dev_err(&dev->dev,
+					"device_add(%s) --> %d\n",
+					intf->dev.bus_id,
+					ret);
+				continue;
+			}
+			if ((intf->cur_altsetting->desc.iInterface) &&
+			    (intf->cur_altsetting->string == NULL)) {
+				intf->cur_altsetting->string = kmalloc(256, GFP_KERNEL);
+				if (intf->cur_altsetting->string)
+					usb_string(dev, intf->cur_altsetting->desc.iInterface,
+						   intf->cur_altsetting->string, 256);
+			}
+			usb_create_sysfs_intf_files (intf);
+		}
+	}
+
+	return ret;
+}
+
+// synchronous request completion model
+EXPORT_SYMBOL(usb_control_msg);
+EXPORT_SYMBOL(usb_bulk_msg);
+
+EXPORT_SYMBOL(usb_sg_init);
+EXPORT_SYMBOL(usb_sg_cancel);
+EXPORT_SYMBOL(usb_sg_wait);
+
+// synchronous control message convenience routines
+EXPORT_SYMBOL(usb_get_descriptor);
+EXPORT_SYMBOL(usb_get_status);
+EXPORT_SYMBOL(usb_get_string);
+EXPORT_SYMBOL(usb_string);
+
+// synchronous calls that also maintain usbcore state
+EXPORT_SYMBOL(usb_clear_halt);
+EXPORT_SYMBOL(usb_reset_configuration);
+EXPORT_SYMBOL(usb_set_interface);
+