Initial import

1 files changed, 1992 insertions, 0 deletions

diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
new file mode 100644
index 000000000..f368d2053
--- /dev/null
+++ b/drivers/usb/core/message.c
@@ -0,0 +1,1992 @@
+/*
+ * message.c - synchronous message handling
+ */
+
+#include <linux/pci.h>	/* for scatterlist macros */
+#include <linux/usb.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/timer.h>
+#include <linux/ctype.h>
+#include <linux/nls.h>
+#include <linux/device.h>
+#include <linux/scatterlist.h>
+#include <linux/usb/quirks.h>
+#include <linux/usb/hcd.h>	/* for usbcore internals */
+#include <asm/byteorder.h>
+
+#include "usb.h"
+
+static void cancel_async_set_config(struct usb_device *udev);
+
+struct api_context {
+	struct completion	done;
+	int			status;
+};
+
+static void usb_api_blocking_completion(struct urb *urb)
+{
+	struct api_context *ctx = urb->context;
+
+	ctx->status = urb->status;
+	complete(&ctx->done);
+}
+
+
+/*
+ * Starts urb and waits for completion or timeout. Note that this call
+ * is NOT interruptible. Many device driver i/o requests should be
+ * interruptible and therefore these drivers should implement their
+ * own interruptible routines.
+ */
+static int usb_start_wait_urb(struct urb *urb, int timeout, int *actual_length)
+{
+	struct api_context ctx;
+	unsigned long expire;
+	int retval;
+
+	init_completion(&ctx.done);
+	urb->context = &ctx;
+	urb->actual_length = 0;
+	retval = usb_submit_urb(urb, GFP_NOIO);
+	if (unlikely(retval))
+		goto out;
+
+	expire = timeout ? msecs_to_jiffies(timeout) : MAX_SCHEDULE_TIMEOUT;
+	if (!wait_for_completion_timeout(&ctx.done, expire)) {
+		usb_kill_urb(urb);
+		retval = (ctx.status == -ENOENT ? -ETIMEDOUT : ctx.status);
+
+		dev_dbg(&urb->dev->dev,
+			"%s timed out on ep%d%s len=%u/%u\n",
+			current->comm,
+			usb_endpoint_num(&urb->ep->desc),
+			usb_urb_dir_in(urb) ? "in" : "out",
+			urb->actual_length,
+			urb->transfer_buffer_length);
+	} else
+		retval = ctx.status;
+out:
+	if (actual_length)
+		*actual_length = urb->actual_length;
+
+	usb_free_urb(urb);
+	return retval;
+}
+
+/*-------------------------------------------------------------------*/
+/* 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.
+ *
+ * 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.
+ *
+ * Return: If successful, the number of bytes transferred. Otherwise, a negative
+ * error number.
+ */
+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;
+	int ret;
+
+	dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_NOIO);
+	if (!dr)
+		return -ENOMEM;
+
+	dr->bRequestType = requesttype;
+	dr->bRequest = request;
+	dr->wValue = cpu_to_le16(value);
+	dr->wIndex = cpu_to_le16(index);
+	dr->wLength = cpu_to_le16(size);
+
+	ret = usb_internal_control_msg(dev, pipe, dr, data, size, timeout);
+
+	kfree(dr);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usb_control_msg);
+
+/**
+ * usb_interrupt_msg - Builds an interrupt 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 interrupt message to a specified endpoint and
+ * waits for the message to complete, or timeout.
+ *
+ * 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.
+ *
+ * Return:
+ * If successful, 0. Otherwise a negative error number. The number of actual
+ * bytes transferred will be stored in the @actual_length parameter.
+ */
+int usb_interrupt_msg(struct usb_device *usb_dev, unsigned int pipe,
+		      void *data, int len, int *actual_length, int timeout)
+{
+	return usb_bulk_msg(usb_dev, pipe, data, len, actual_length, timeout);
+}
+EXPORT_SYMBOL_GPL(usb_interrupt_msg);
+
+/**
+ * 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.
+ *
+ * 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.
+ *
+ * Because there is no usb_interrupt_msg() and no USBDEVFS_INTERRUPT ioctl,
+ * users are forced to abuse this routine by using it to submit URBs for
+ * interrupt endpoints.  We will take the liberty of creating an interrupt URB
+ * (with the default interval) if the target is an interrupt endpoint.
+ *
+ * Return:
+ * If successful, 0. Otherwise a negative error number. The number of actual
+ * bytes transferred will be stored in the @actual_length parameter.
+ *
+ */
+int usb_bulk_msg(struct usb_device *usb_dev, unsigned int pipe,
+		 void *data, int len, int *actual_length, int timeout)
+{
+	struct urb *urb;
+	struct usb_host_endpoint *ep;
+
+	ep = usb_pipe_endpoint(usb_dev, pipe);
+	if (!ep || len < 0)
+		return -EINVAL;
+
+	urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!urb)
+		return -ENOMEM;
+
+	if ((ep->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) ==
+			USB_ENDPOINT_XFER_INT) {
+		pipe = (pipe & ~(3 << 30)) | (PIPE_INTERRUPT << 30);
+		usb_fill_int_urb(urb, usb_dev, pipe, data, len,
+				usb_api_blocking_completion, NULL,
+				ep->desc.bInterval);
+	} else
+		usb_fill_bulk_urb(urb, usb_dev, pipe, data, len,
+				usb_api_blocking_completion, NULL);
+
+	return usb_start_wait_urb(urb, timeout, actual_length);
+}
+EXPORT_SYMBOL_GPL(usb_bulk_msg);
+
+/*-------------------------------------------------------------------*/
+
+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;
+	}
+	io->dev = NULL;
+}
+
+static void sg_complete(struct urb *urb)
+{
+	struct usb_sg_request *io = urb->context;
+	int status = urb->status;
+
+	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
+				|| 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_endpoint_num(&urb->ep->desc),
+			usb_urb_dir_in(urb) ? "in" : "out",
+			status, io->status);
+		/* BUG (); */
+	}
+
+	if (io->status == 0 && status && status != -ECONNRESET) {
+		int i, found, retval;
+
+		io->status = 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) {
+				retval = usb_unlink_urb(io->urbs[i]);
+				if (retval != -EINPROGRESS &&
+				    retval != -ENODEV &&
+				    retval != -EBUSY &&
+				    retval != -EIDRM)
+					dev_err(&io->dev->dev,
+						"%s, unlink --> %d\n",
+						__func__, retval);
+			} else if (urb == io->urbs[i])
+				found = 1;
+		}
+		spin_lock(&io->lock);
+	}
+
+	/* 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
+ *
+ * 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.
+ *
+ * Return: Zero for success, else a negative errno value.
+ */
+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, gfp_t mem_flags)
+{
+	int i;
+	int urb_flags;
+	int use_sg;
+
+	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;
+
+	if (dev->bus->sg_tablesize > 0) {
+		use_sg = true;
+		io->entries = 1;
+	} else {
+		use_sg = false;
+		io->entries = nents;
+	}
+
+	/* initialize all the urbs we'll use */
+	io->urbs = kmalloc(io->entries * sizeof(*io->urbs), mem_flags);
+	if (!io->urbs)
+		goto nomem;
+
+	urb_flags = URB_NO_INTERRUPT;
+	if (usb_pipein(pipe))
+		urb_flags |= URB_SHORT_NOT_OK;
+
+	for_each_sg(sg, sg, io->entries, i) {
+		struct urb *urb;
+		unsigned len;
+
+		urb = usb_alloc_urb(0, mem_flags);
+		if (!urb) {
+			io->entries = i;
+			goto nomem;
+		}
+		io->urbs[i] = urb;
+
+		urb->dev = NULL;
+		urb->pipe = pipe;
+		urb->interval = period;
+		urb->transfer_flags = urb_flags;
+		urb->complete = sg_complete;
+		urb->context = io;
+		urb->sg = sg;
+
+		if (use_sg) {
+			/* There is no single transfer buffer */
+			urb->transfer_buffer = NULL;
+			urb->num_sgs = nents;
+
+			/* A length of zero means transfer the whole sg list */
+			len = length;
+			if (len == 0) {
+				struct scatterlist	*sg2;
+				int			j;
+
+				for_each_sg(sg, sg2, nents, j)
+					len += sg2->length;
+			}
+		} else {
+			/*
+			 * Some systems can't use DMA; they use PIO instead.
+			 * For their sakes, transfer_buffer is set whenever
+			 * possible.
+			 */
+			if (!PageHighMem(sg_page(sg)))
+				urb->transfer_buffer = sg_virt(sg);
+			else
+				urb->transfer_buffer = NULL;
+
+			len = sg->length;
+			if (length) {
+				len = min_t(size_t, len, length);
+				length -= len;
+				if (length == 0)
+					io->entries = i + 1;
+			}
+		}
+		urb->transfer_buffer_length = len;
+	}
+	io->urbs[--i]->transfer_flags &= ~URB_NO_INTERRUPT;
+
+	/* transaction state */
+	io->count = io->entries;
+	io->status = 0;
+	io->bytes = 0;
+	init_completion(&io->complete);
+	return 0;
+
+nomem:
+	sg_clean(io);
+	return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(usb_sg_init);
+
+/**
+ * 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) cancellation, 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).
+ *
+ * It is not necessary to call this function to reserve bandwidth for devices
+ * under an xHCI host controller, as the bandwidth is reserved when the
+ * configuration or interface alt setting is selected.
+ */
+void usb_sg_wait(struct usb_sg_request *io)
+{
+	int i;
+	int entries = io->entries;
+
+	/* queue the urbs.  */
+	spin_lock_irq(&io->lock);
+	i = 0;
+	while (i < entries && !io->status) {
+		int retval;
+
+		io->urbs[i]->dev = io->dev;
+		retval = usb_submit_urb(io->urbs[i], GFP_ATOMIC);
+
+		/* after we submit, let completions or cancellations 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:
+			retval = 0;
+			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:
+			++i;
+			cpu_relax();
+			break;
+
+			/* fail any uncompleted urbs */
+		default:
+			io->urbs[i]->status = retval;
+			dev_dbg(&io->dev->dev, "%s, submit --> %d\n",
+				__func__, 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);
+}
+EXPORT_SYMBOL_GPL(usb_sg_wait);
+
+/**
+ * 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 != -ENODEV
+					&& retval != -EBUSY
+					&& retval != -EIDRM)
+				dev_warn(&io->dev->dev, "%s, unlink --> %d\n",
+					__func__, retval);
+		}
+		spin_lock(&io->lock);
+	}
+	spin_unlock_irqrestore(&io->lock, flags);
+}
+EXPORT_SYMBOL_GPL(usb_sg_cancel);
+
+/*-------------------------------------------------------------------*/
+
+/**
+ * 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.
+ *
+ * Return: 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 error; 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 != -ETIMEDOUT)
+			continue;
+		if (result > 1 && ((u8 *)buf)[1] != type) {
+			result = -ENODATA;
+			continue;
+		}
+		break;
+	}
+	return result;
+}
+EXPORT_SYMBOL_GPL(usb_get_descriptor);
+
+/**
+ * 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.
+ *
+ * Return: The number of bytes received on success, or else the status code
+ * returned by the underlying usb_control_msg() call.
+ */
+static 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)
+			continue;
+		if (result > 1 && ((u8 *) buf)[1] != USB_DT_STRING) {
+			result = -ENODATA;
+			continue;
+		}
+		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 */
+	if (dev->quirks & USB_QUIRK_STRING_FETCH_255)
+		rc = -EIO;
+	else
+		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;
+}
+
+static int usb_get_langid(struct usb_device *dev, unsigned char *tbuf)
+{
+	int err;
+
+	if (dev->have_langid)
+		return 0;
+
+	if (dev->string_langid < 0)
+		return -EPIPE;
+
+	err = usb_string_sub(dev, 0, 0, tbuf);
+
+	/* If the string was reported but is malformed, default to english
+	 * (0x0409) */
+	if (err == -ENODATA || (err > 0 && err < 4)) {
+		dev->string_langid = 0x0409;
+		dev->have_langid = 1;
+		dev_err(&dev->dev,
+			"language id specifier not provided by device, defaulting to English\n");
+		return 0;
+	}
+
+	/* In case of all other errors, we assume the device is not able to
+	 * deal with strings at all. Set string_langid to -1 in order to
+	 * prevent any string to be retrieved from the device */
+	if (err < 0) {
+		dev_err(&dev->dev, "string descriptor 0 read error: %d\n",
+					err);
+		dev->string_langid = -1;
+		return -EPIPE;
+	}
+
+	/* always use the first langid listed */
+	dev->string_langid = tbuf[2] | (tbuf[3] << 8);
+	dev->have_langid = 1;
+	dev_dbg(&dev->dev, "default language 0x%04x\n",
+				dev->string_langid);
+	return 0;
+}
+
+/**
+ * usb_string - returns UTF-8 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 UTF-8 encoded ones
+ * that are more usable in most kernel contexts.  Note that this function
+ * chooses strings in the first language supported by the device.
+ *
+ * This call is synchronous, and may not be used in an interrupt context.
+ *
+ * Return: 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;
+
+	if (dev->state == USB_STATE_SUSPENDED)
+		return -EHOSTUNREACH;
+	if (size <= 0 || !buf || !index)
+		return -EINVAL;
+	buf[0] = 0;
+	tbuf = kmalloc(256, GFP_NOIO);
+	if (!tbuf)
+		return -ENOMEM;
+
+	err = usb_get_langid(dev, tbuf);
+	if (err < 0)
+		goto errout;
+
+	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 */
+	err = utf16s_to_utf8s((wchar_t *) &tbuf[2], (err - 2) / 2,
+			UTF16_LITTLE_ENDIAN, buf, size);
+	buf[err] = 0;
+
+	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;
+}
+EXPORT_SYMBOL_GPL(usb_string);
+
+/* one UTF-8-encoded 16-bit character has at most three bytes */
+#define MAX_USB_STRING_SIZE (127 * 3 + 1)
+
+/**
+ * usb_cache_string - read a string descriptor and cache it for later use
+ * @udev: the device whose string descriptor is being read
+ * @index: the descriptor index
+ *
+ * Return: A pointer to a kmalloc'ed buffer containing the descriptor string,
+ * or %NULL if the index is 0 or the string could not be read.
+ */
+char *usb_cache_string(struct usb_device *udev, int index)
+{
+	char *buf;
+	char *smallbuf = NULL;
+	int len;
+
+	if (index <= 0)
+		return NULL;
+
+	buf = kmalloc(MAX_USB_STRING_SIZE, GFP_NOIO);
+	if (buf) {
+		len = usb_string(udev, index, buf, MAX_USB_STRING_SIZE);
+		if (len > 0) {
+			smallbuf = kmalloc(++len, GFP_NOIO);
+			if (!smallbuf)
+				return buf;
+			memcpy(smallbuf, buf, len);
+		}
+		kfree(buf);
+	}
+	return smallbuf;
+}
+
+/*
+ * 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.
+ *
+ * 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.
+ *
+ * Return: 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 0 and the status value in *@data (in host byte order) on success,
+ * or else the status code from the underlying usb_control_msg() call.
+ */
+int usb_get_status(struct usb_device *dev, int type, int target, void *data)
+{
+	int ret;
+	__le16 *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);
+
+	if (ret == 2) {
+		*(u16 *) data = le16_to_cpu(*status);
+		ret = 0;
+	} else if (ret >= 0) {
+		ret = -EIO;
+	}
+	kfree(status);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usb_get_status);
+
+/**
+ * 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.
+ *
+ * Return: 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.
+	 */
+
+	usb_reset_endpoint(dev, endp);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_clear_halt);
+
+static int create_intf_ep_devs(struct usb_interface *intf)
+{
+	struct usb_device *udev = interface_to_usbdev(intf);
+	struct usb_host_interface *alt = intf->cur_altsetting;
+	int i;
+
+	if (intf->ep_devs_created || intf->unregistering)
+		return 0;
+
+	for (i = 0; i < alt->desc.bNumEndpoints; ++i)
+		(void) usb_create_ep_devs(&intf->dev, &alt->endpoint[i], udev);
+	intf->ep_devs_created = 1;
+	return 0;
+}
+
+static void remove_intf_ep_devs(struct usb_interface *intf)
+{
+	struct usb_host_interface *alt = intf->cur_altsetting;
+	int i;
+
+	if (!intf->ep_devs_created)
+		return;
+
+	for (i = 0; i < alt->desc.bNumEndpoints; ++i)
+		usb_remove_ep_devs(&alt->endpoint[i]);
+	intf->ep_devs_created = 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
+ * @reset_hardware: flag to erase any endpoint state stored in the
+ *	controller hardware
+ *
+ * Disables the endpoint for URB submission and nukes all pending URBs.
+ * If @reset_hardware is set then also deallocates hcd/hardware state
+ * for the endpoint.
+ */
+void usb_disable_endpoint(struct usb_device *dev, unsigned int epaddr,
+		bool reset_hardware)
+{
+	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];
+		if (reset_hardware)
+			dev->ep_out[epnum] = NULL;
+	} else {
+		ep = dev->ep_in[epnum];
+		if (reset_hardware)
+			dev->ep_in[epnum] = NULL;
+	}
+	if (ep) {
+		ep->enabled = 0;
+		usb_hcd_flush_endpoint(dev, ep);
+		if (reset_hardware)
+			usb_hcd_disable_endpoint(dev, ep);
+	}
+}
+
+/**
+ * usb_reset_endpoint - Reset an endpoint's state.
+ * @dev: the device whose endpoint is to be reset
+ * @epaddr: the endpoint's address.  Endpoint number for output,
+ *	endpoint number + USB_DIR_IN for input
+ *
+ * Resets any host-side endpoint state such as the toggle bit,
+ * sequence number or current window.
+ */
+void usb_reset_endpoint(struct usb_device *dev, unsigned int epaddr)
+{
+	unsigned int epnum = epaddr & USB_ENDPOINT_NUMBER_MASK;
+	struct usb_host_endpoint *ep;
+
+	if (usb_endpoint_out(epaddr))
+		ep = dev->ep_out[epnum];
+	else
+		ep = dev->ep_in[epnum];
+	if (ep)
+		usb_hcd_reset_endpoint(dev, ep);
+}
+EXPORT_SYMBOL_GPL(usb_reset_endpoint);
+
+
+/**
+ * usb_disable_interface -- Disable all endpoints for an interface
+ * @dev: the device whose interface is being disabled
+ * @intf: pointer to the interface descriptor
+ * @reset_hardware: flag to erase any endpoint state stored in the
+ *	controller hardware
+ *
+ * Disables all the endpoints for the interface's current altsetting.
+ */
+void usb_disable_interface(struct usb_device *dev, struct usb_interface *intf,
+		bool reset_hardware)
+{
+	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,
+				reset_hardware);
+	}
+}
+
+/**
+ * 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;
+	struct usb_hcd *hcd = bus_to_hcd(dev->bus);
+
+	/* getting rid of interfaces will disconnect
+	 * any drivers bound to them (a key side effect)
+	 */
+	if (dev->actconfig) {
+		/*
+		 * FIXME: In order to avoid self-deadlock involving the
+		 * bandwidth_mutex, we have to mark all the interfaces
+		 * before unregistering any of them.
+		 */
+		for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++)
+			dev->actconfig->interface[i]->unregistering = 1;
+
+		for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++) {
+			struct usb_interface	*interface;
+
+			/* remove this interface if it has been registered */
+			interface = dev->actconfig->interface[i];
+			if (!device_is_registered(&interface->dev))
+				continue;
+			dev_dbg(&dev->dev, "unregistering interface %s\n",
+				dev_name(&interface->dev));
+			remove_intf_ep_devs(interface);
+			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;
+		}
+
+		if (dev->usb2_hw_lpm_enabled == 1)
+			usb_set_usb2_hardware_lpm(dev, 0);
+		usb_unlocked_disable_lpm(dev);
+		usb_disable_ltm(dev);
+
+		dev->actconfig = NULL;
+		if (dev->state == USB_STATE_CONFIGURED)
+			usb_set_device_state(dev, USB_STATE_ADDRESS);
+	}
+
+	dev_dbg(&dev->dev, "%s nuking %s URBs\n", __func__,
+		skip_ep0 ? "non-ep0" : "all");
+	if (hcd->driver->check_bandwidth) {
+		/* First pass: Cancel URBs, leave endpoint pointers intact. */
+		for (i = skip_ep0; i < 16; ++i) {
+			usb_disable_endpoint(dev, i, false);
+			usb_disable_endpoint(dev, i + USB_DIR_IN, false);
+		}
+		/* Remove endpoints from the host controller internal state */
+		mutex_lock(hcd->bandwidth_mutex);
+		usb_hcd_alloc_bandwidth(dev, NULL, NULL, NULL);
+		mutex_unlock(hcd->bandwidth_mutex);
+		/* Second pass: remove endpoint pointers */
+	}
+	for (i = skip_ep0; i < 16; ++i) {
+		usb_disable_endpoint(dev, i, true);
+		usb_disable_endpoint(dev, i + USB_DIR_IN, true);
+	}
+}
+
+/**
+ * usb_enable_endpoint - Enable an endpoint for USB communications
+ * @dev: the device whose interface is being enabled
+ * @ep: the endpoint
+ * @reset_ep: flag to reset the endpoint state
+ *
+ * Resets the endpoint state if asked, and sets dev->ep_{in,out} pointers.
+ * For control endpoints, both the input and output sides are handled.
+ */
+void usb_enable_endpoint(struct usb_device *dev, struct usb_host_endpoint *ep,
+		bool reset_ep)
+{
+	int epnum = usb_endpoint_num(&ep->desc);
+	int is_out = usb_endpoint_dir_out(&ep->desc);
+	int is_control = usb_endpoint_xfer_control(&ep->desc);
+
+	if (reset_ep)
+		usb_hcd_reset_endpoint(dev, ep);
+	if (is_out || is_control)
+		dev->ep_out[epnum] = ep;
+	if (!is_out || is_control)
+		dev->ep_in[epnum] = ep;
+	ep->enabled = 1;
+}
+
+/**
+ * usb_enable_interface - Enable all the endpoints for an interface
+ * @dev: the device whose interface is being enabled
+ * @intf: pointer to the interface descriptor
+ * @reset_eps: flag to reset the endpoints' state
+ *
+ * Enables all the endpoints for the interface's current altsetting.
+ */
+void usb_enable_interface(struct usb_device *dev,
+		struct usb_interface *intf, bool reset_eps)
+{
+	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], reset_eps);
+}
+
+/**
+ * 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).
+ *
+ * Return: 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;
+	struct usb_hcd *hcd = bus_to_hcd(dev->bus);
+	int i, ret, manual = 0;
+	unsigned int epaddr;
+	unsigned int pipe;
+
+	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;
+	}
+	if (iface->unregistering)
+		return -ENODEV;
+
+	alt = usb_altnum_to_altsetting(iface, alternate);
+	if (!alt) {
+		dev_warn(&dev->dev, "selecting invalid altsetting %d\n",
+			 alternate);
+		return -EINVAL;
+	}
+
+	/* Make sure we have enough bandwidth for this alternate interface.
+	 * Remove the current alt setting and add the new alt setting.
+	 */
+	mutex_lock(hcd->bandwidth_mutex);
+	/* Disable LPM, and re-enable it once the new alt setting is installed,
+	 * so that the xHCI driver can recalculate the U1/U2 timeouts.
+	 */
+	if (usb_disable_lpm(dev)) {
+		dev_err(&iface->dev, "%s Failed to disable LPM\n.", __func__);
+		mutex_unlock(hcd->bandwidth_mutex);
+		return -ENOMEM;
+	}
+	/* Changing alt-setting also frees any allocated streams */
+	for (i = 0; i < iface->cur_altsetting->desc.bNumEndpoints; i++)
+		iface->cur_altsetting->endpoint[i].streams = 0;
+
+	ret = usb_hcd_alloc_bandwidth(dev, NULL, iface->cur_altsetting, alt);
+	if (ret < 0) {
+		dev_info(&dev->dev, "Not enough bandwidth for altsetting %d\n",
+				alternate);
+		usb_enable_lpm(dev);
+		mutex_unlock(hcd->bandwidth_mutex);
+		return ret;
+	}
+
+	if (dev->quirks & USB_QUIRK_NO_SET_INTF)
+		ret = -EPIPE;
+	else
+		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) {
+		/* Re-instate the old alt setting */
+		usb_hcd_alloc_bandwidth(dev, NULL, alt, iface->cur_altsetting);
+		usb_enable_lpm(dev);
+		mutex_unlock(hcd->bandwidth_mutex);
+		return ret;
+	}
+	mutex_unlock(hcd->bandwidth_mutex);
+
+	/* 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 */
+	if (iface->cur_altsetting != alt) {
+		remove_intf_ep_devs(iface);
+		usb_remove_sysfs_intf_files(iface);
+	}
+	usb_disable_interface(dev, iface, true);
+
+	iface->cur_altsetting = alt;
+
+	/* Now that the interface is installed, re-enable LPM. */
+	usb_unlocked_enable_lpm(dev);
+
+	/* If the interface only has one altsetting and the device didn't
+	 * accept the request, 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++) {
+			epaddr = alt->endpoint[i].desc.bEndpointAddress;
+			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, true);
+	if (device_is_registered(&iface->dev)) {
+		usb_create_sysfs_intf_files(iface);
+		create_intf_ep_devs(iface);
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_set_interface);
+
+/**
+ * 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 endpoint state (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.  Be careful though;
+ * some devices don't support the SET_INTERFACE request, and others won't
+ * reset all the interface state (notably endpoint state).  Resetting the whole
+ * configuration would affect other drivers' interfaces.
+ *
+ * The caller must own the device lock.
+ *
+ * Return: Zero on success, else a negative error code.
+ */
+int usb_reset_configuration(struct usb_device *dev)
+{
+	int			i, retval;
+	struct usb_host_config	*config;
+	struct usb_hcd *hcd = bus_to_hcd(dev->bus);
+
+	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, true);
+		usb_disable_endpoint(dev, i + USB_DIR_IN, true);
+	}
+
+	config = dev->actconfig;
+	retval = 0;
+	mutex_lock(hcd->bandwidth_mutex);
+	/* Disable LPM, and re-enable it once the configuration is reset, so
+	 * that the xHCI driver can recalculate the U1/U2 timeouts.
+	 */
+	if (usb_disable_lpm(dev)) {
+		dev_err(&dev->dev, "%s Failed to disable LPM\n.", __func__);
+		mutex_unlock(hcd->bandwidth_mutex);
+		return -ENOMEM;
+	}
+	/* Make sure we have enough bandwidth for each alternate setting 0 */
+	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);
+		if (!alt)
+			alt = &intf->altsetting[0];
+		if (alt != intf->cur_altsetting)
+			retval = usb_hcd_alloc_bandwidth(dev, NULL,
+					intf->cur_altsetting, alt);
+		if (retval < 0)
+			break;
+	}
+	/* If not, reinstate the old alternate settings */
+	if (retval < 0) {
+reset_old_alts:
+		for (i--; i >= 0; i--) {
+			struct usb_interface *intf = config->interface[i];
+			struct usb_host_interface *alt;
+
+			alt = usb_altnum_to_altsetting(intf, 0);
+			if (!alt)
+				alt = &intf->altsetting[0];
+			if (alt != intf->cur_altsetting)
+				usb_hcd_alloc_bandwidth(dev, NULL,
+						alt, intf->cur_altsetting);
+		}
+		usb_enable_lpm(dev);
+		mutex_unlock(hcd->bandwidth_mutex);
+		return retval;
+	}
+	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)
+		goto reset_old_alts;
+	mutex_unlock(hcd->bandwidth_mutex);
+
+	/* 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];
+
+		if (alt != intf->cur_altsetting) {
+			remove_intf_ep_devs(intf);
+			usb_remove_sysfs_intf_files(intf);
+		}
+		intf->cur_altsetting = alt;
+		usb_enable_interface(dev, intf, true);
+		if (device_is_registered(&intf->dev)) {
+			usb_create_sysfs_intf_files(intf);
+			create_intf_ep_devs(intf);
+		}
+	}
+	/* Now that the interfaces are installed, re-enable LPM. */
+	usb_unlocked_enable_lpm(dev);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_reset_configuration);
+
+static void usb_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);
+	usb_put_dev(interface_to_usbdev(intf));
+	kfree(intf);
+}
+
+static int usb_if_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct usb_device *usb_dev;
+	struct usb_interface *intf;
+	struct usb_host_interface *alt;
+
+	intf = to_usb_interface(dev);
+	usb_dev = interface_to_usbdev(intf);
+	alt = intf->cur_altsetting;
+
+	if (add_uevent_var(env, "INTERFACE=%d/%d/%d",
+		   alt->desc.bInterfaceClass,
+		   alt->desc.bInterfaceSubClass,
+		   alt->desc.bInterfaceProtocol))
+		return -ENOMEM;
+
+	if (add_uevent_var(env,
+		   "MODALIAS=usb:"
+		   "v%04Xp%04Xd%04Xdc%02Xdsc%02Xdp%02Xic%02Xisc%02Xip%02Xin%02X",
+		   le16_to_cpu(usb_dev->descriptor.idVendor),
+		   le16_to_cpu(usb_dev->descriptor.idProduct),
+		   le16_to_cpu(usb_dev->descriptor.bcdDevice),
+		   usb_dev->descriptor.bDeviceClass,
+		   usb_dev->descriptor.bDeviceSubClass,
+		   usb_dev->descriptor.bDeviceProtocol,
+		   alt->desc.bInterfaceClass,
+		   alt->desc.bInterfaceSubClass,
+		   alt->desc.bInterfaceProtocol,
+		   alt->desc.bInterfaceNumber))
+		return -ENOMEM;
+
+	return 0;
+}
+
+struct device_type usb_if_device_type = {
+	.name =		"usb_interface",
+	.release =	usb_release_interface,
+	.uevent =	usb_if_uevent,
+};
+
+static struct usb_interface_assoc_descriptor *find_iad(struct usb_device *dev,
+						struct usb_host_config *config,
+						u8 inum)
+{
+	struct usb_interface_assoc_descriptor *retval = NULL;
+	struct usb_interface_assoc_descriptor *intf_assoc;
+	int first_intf;
+	int last_intf;
+	int i;
+
+	for (i = 0; (i < USB_MAXIADS && config->intf_assoc[i]); i++) {
+		intf_assoc = config->intf_assoc[i];
+		if (intf_assoc->bInterfaceCount == 0)
+			continue;
+
+		first_intf = intf_assoc->bFirstInterface;
+		last_intf = first_intf + (intf_assoc->bInterfaceCount - 1);
+		if (inum >= first_intf && inum <= last_intf) {
+			if (!retval)
+				retval = intf_assoc;
+			else
+				dev_err(&dev->dev, "Interface #%d referenced"
+					" by multiple IADs\n", inum);
+		}
+	}
+
+	return retval;
+}
+
+
+/*
+ * Internal function to queue a device reset
+ * See usb_queue_reset_device() for more details
+ */
+static void __usb_queue_reset_device(struct work_struct *ws)
+{
+	int rc;
+	struct usb_interface *iface =
+		container_of(ws, struct usb_interface, reset_ws);
+	struct usb_device *udev = interface_to_usbdev(iface);
+
+	rc = usb_lock_device_for_reset(udev, iface);
+	if (rc >= 0) {
+		usb_reset_device(udev);
+		usb_unlock_device(udev);
+	}
+	usb_put_intf(iface);	/* Undo _get_ in usb_queue_reset_device() */
+}
+
+
+/*
+ * 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.
+ *
+ * @configuration is the value of the configuration to be installed.
+ * According to the USB spec (e.g. section 9.1.1.5), configuration values
+ * must be non-zero; a value of zero indicates that the device in
+ * unconfigured.  However some devices erroneously use 0 as one of their
+ * configuration values.  To help manage such devices, this routine will
+ * accept @configuration = -1 as indicating the device should be put in
+ * an unconfigured state.
+ *
+ * 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 a non-authorized device (dev->authorized == 0) will only
+ * be put in unconfigured mode.
+ *
+ * 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 mutex; usb interface driver probe() methods cannot use this routine.
+ *
+ * Returns zero on success, or else the status code returned by the
+ * underlying call that failed.  On successful 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;
+	struct usb_hcd *hcd = bus_to_hcd(dev->bus);
+	int n, nintf;
+
+	if (dev->authorized == 0 || configuration == -1)
+		configuration = 0;
+	else {
+		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.
+	 * Use -1 if you really want to unconfigure the device.
+	 */
+	if (cp && configuration == 0)
+		dev_warn(&dev->dev, "config 0 descriptor??\n");
+
+	/* 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_NOIO);
+		if (!new_interfaces) {
+			dev_err(&dev->dev, "Out of memory\n");
+			return -ENOMEM;
+		}
+
+		for (; n < nintf; ++n) {
+			new_interfaces[n] = kzalloc(
+					sizeof(struct usb_interface),
+					GFP_NOIO);
+			if (!new_interfaces[n]) {
+				dev_err(&dev->dev, "Out of memory\n");
+				ret = -ENOMEM;
+free_interfaces:
+				while (--n >= 0)
+					kfree(new_interfaces[n]);
+				kfree(new_interfaces);
+				return ret;
+			}
+		}
+
+		i = dev->bus_mA - usb_get_max_power(dev, cp);
+		if (i < 0)
+			dev_warn(&dev->dev, "new config #%d exceeds power "
+					"limit by %dmA\n",
+					configuration, -i);
+	}
+
+	/* Wake up the device so we can send it the Set-Config request */
+	ret = usb_autoresume_device(dev);
+	if (ret)
+		goto free_interfaces;
+
+	/* 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 */
+
+	/* Get rid of pending async Set-Config requests for this device */
+	cancel_async_set_config(dev);
+
+	/* Make sure we have bandwidth (and available HCD resources) for this
+	 * configuration.  Remove endpoints from the schedule if we're dropping
+	 * this configuration to set configuration 0.  After this point, the
+	 * host controller will not allow submissions to dropped endpoints.  If
+	 * this call fails, the device state is unchanged.
+	 */
+	mutex_lock(hcd->bandwidth_mutex);
+	/* Disable LPM, and re-enable it once the new configuration is
+	 * installed, so that the xHCI driver can recalculate the U1/U2
+	 * timeouts.
+	 */
+	if (dev->actconfig && usb_disable_lpm(dev)) {
+		dev_err(&dev->dev, "%s Failed to disable LPM\n.", __func__);
+		mutex_unlock(hcd->bandwidth_mutex);
+		ret = -ENOMEM;
+		goto free_interfaces;
+	}
+	ret = usb_hcd_alloc_bandwidth(dev, cp, NULL, NULL);
+	if (ret < 0) {
+		if (dev->actconfig)
+			usb_enable_lpm(dev);
+		mutex_unlock(hcd->bandwidth_mutex);
+		usb_autosuspend_device(dev);
+		goto free_interfaces;
+	}
+
+	/*
+	 * 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];
+		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->intf_assoc =
+			find_iad(dev, cp, alt->desc.bInterfaceNumber);
+		intf->cur_altsetting = alt;
+		usb_enable_interface(dev, intf, true);
+		intf->dev.parent = &dev->dev;
+		intf->dev.driver = NULL;
+		intf->dev.bus = &usb_bus_type;
+		intf->dev.type = &usb_if_device_type;
+		intf->dev.groups = usb_interface_groups;
+		intf->dev.dma_mask = dev->dev.dma_mask;
+		INIT_WORK(&intf->reset_ws, __usb_queue_reset_device);
+		intf->minor = -1;
+		device_initialize(&intf->dev);
+		pm_runtime_no_callbacks(&intf->dev);
+		dev_set_name(&intf->dev, "%d-%s:%d.%d",
+			dev->bus->busnum, dev->devpath,
+			configuration, alt->desc.bInterfaceNumber);
+		usb_get_dev(dev);
+	}
+	kfree(new_interfaces);
+
+	ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
+			      USB_REQ_SET_CONFIGURATION, 0, configuration, 0,
+			      NULL, 0, USB_CTRL_SET_TIMEOUT);
+	if (ret < 0 && cp) {
+		/*
+		 * All the old state is gone, so what else can we do?
+		 * The device is probably useless now anyway.
+		 */
+		usb_hcd_alloc_bandwidth(dev, NULL, NULL, NULL);
+		for (i = 0; i < nintf; ++i) {
+			usb_disable_interface(dev, cp->interface[i], true);
+			put_device(&cp->interface[i]->dev);
+			cp->interface[i] = NULL;
+		}
+		cp = NULL;
+	}
+
+	dev->actconfig = cp;
+	mutex_unlock(hcd->bandwidth_mutex);
+
+	if (!cp) {
+		usb_set_device_state(dev, USB_STATE_ADDRESS);
+
+		/* Leave LPM disabled while the device is unconfigured. */
+		usb_autosuspend_device(dev);
+		return ret;
+	}
+	usb_set_device_state(dev, USB_STATE_CONFIGURED);
+
+	if (cp->string == NULL &&
+			!(dev->quirks & USB_QUIRK_CONFIG_INTF_STRINGS))
+		cp->string = usb_cache_string(dev, cp->desc.iConfiguration);
+
+	/* Now that the interfaces are installed, re-enable LPM. */
+	usb_unlocked_enable_lpm(dev);
+	/* Enable LTM if it was turned off by usb_disable_device. */
+	usb_enable_ltm(dev);
+
+	/* 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];
+
+		dev_dbg(&dev->dev,
+			"adding %s (config #%d, interface %d)\n",
+			dev_name(&intf->dev), configuration,
+			intf->cur_altsetting->desc.bInterfaceNumber);
+		device_enable_async_suspend(&intf->dev);
+		ret = device_add(&intf->dev);
+		if (ret != 0) {
+			dev_err(&dev->dev, "device_add(%s) --> %d\n",
+				dev_name(&intf->dev), ret);
+			continue;
+		}
+		create_intf_ep_devs(intf);
+	}
+
+	usb_autosuspend_device(dev);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_set_configuration);
+
+static LIST_HEAD(set_config_list);
+static DEFINE_SPINLOCK(set_config_lock);
+
+struct set_config_request {
+	struct usb_device	*udev;
+	int			config;
+	struct work_struct	work;
+	struct list_head	node;
+};
+
+/* Worker routine for usb_driver_set_configuration() */
+static void driver_set_config_work(struct work_struct *work)
+{
+	struct set_config_request *req =
+		container_of(work, struct set_config_request, work);
+	struct usb_device *udev = req->udev;
+
+	usb_lock_device(udev);
+	spin_lock(&set_config_lock);
+	list_del(&req->node);
+	spin_unlock(&set_config_lock);
+
+	if (req->config >= -1)		/* Is req still valid? */
+		usb_set_configuration(udev, req->config);
+	usb_unlock_device(udev);
+	usb_put_dev(udev);
+	kfree(req);
+}
+
+/* Cancel pending Set-Config requests for a device whose configuration
+ * was just changed
+ */
+static void cancel_async_set_config(struct usb_device *udev)
+{
+	struct set_config_request *req;
+
+	spin_lock(&set_config_lock);
+	list_for_each_entry(req, &set_config_list, node) {
+		if (req->udev == udev)
+			req->config = -999;	/* Mark as cancelled */
+	}
+	spin_unlock(&set_config_lock);
+}
+
+/**
+ * usb_driver_set_configuration - Provide a way for drivers to change device configurations
+ * @udev: the device whose configuration is being updated
+ * @config: the configuration being chosen.
+ * Context: In process context, must be able to sleep
+ *
+ * Device interface drivers are not allowed to change device configurations.
+ * This is because changing configurations will destroy the interface the
+ * driver is bound to and create new ones; it would be like a floppy-disk
+ * driver telling the computer to replace the floppy-disk drive with a
+ * tape drive!
+ *
+ * Still, in certain specialized circumstances the need may arise.  This
+ * routine gets around the normal restrictions by using a work thread to
+ * submit the change-config request.
+ *
+ * Return: 0 if the request was successfully queued, error code otherwise.
+ * The caller has no way to know whether the queued request will eventually
+ * succeed.
+ */
+int usb_driver_set_configuration(struct usb_device *udev, int config)
+{
+	struct set_config_request *req;
+
+	req = kmalloc(sizeof(*req), GFP_KERNEL);
+	if (!req)
+		return -ENOMEM;
+	req->udev = udev;
+	req->config = config;
+	INIT_WORK(&req->work, driver_set_config_work);
+
+	spin_lock(&set_config_lock);
+	list_add(&req->node, &set_config_list);
+	spin_unlock(&set_config_lock);
+
+	usb_get_dev(udev);
+	schedule_work(&req->work);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_driver_set_configuration);