text: #include <linux/usb.h>
  #include <linux/usb/ch9.h>
  #include <linux/usb/hcd.h>
  #include <linux/usb/quirks.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/device.h>
  #include <asm/byteorder.h>
  #include "usb.h"
  
  
  #define USB_MAXALTSETTING		128	/* Hard limit */
  #define USB_MAXENDPOINTS		30	/* Hard limit */
  
  #define USB_MAXCONFIG			8	/* Arbitrary limit */
  
  
  static inline const char *plural(int n)
  {
  	return (n == 1 ? "" : "s");
  }
  
  static int find_next_descriptor(unsigned char *buffer, int size,
      int dt1, int dt2, int *num_skipped)
  {
  	struct usb_descriptor_header *h;
  	int n = 0;
  	unsigned char *buffer0 = buffer;
  
  	/* Find the next descriptor of type dt1 or dt2 */
  	while (size > 0) {
  		h = (struct usb_descriptor_header *) buffer;
  		if (h->bDescriptorType == dt1 || h->bDescriptorType == dt2)
  			break;
  		buffer += h->bLength;
  		size -= h->bLength;
  		++n;
  	}
  
  	/* Store the number of descriptors skipped and return the
  	 * number of bytes skipped */
  	if (num_skipped)
  		*num_skipped = n;
  	return buffer - buffer0;
  }
  
  static void usb_parse_ss_endpoint_companion(struct device *ddev, int cfgno,
  		int inum, int asnum, struct usb_host_endpoint *ep,
  		unsigned char *buffer, int size)
  {
  	struct usb_ss_ep_comp_descriptor *desc;
  	int max_tx;
  
  	/* The SuperSpeed endpoint companion descriptor is supposed to
  	 * be the first thing immediately following the endpoint descriptor.
  	 */
  	desc = (struct usb_ss_ep_comp_descriptor *) buffer;
  	if (desc->bDescriptorType != USB_DT_SS_ENDPOINT_COMP ||
  			size < USB_DT_SS_EP_COMP_SIZE) {
  		dev_warn(ddev, "No SuperSpeed endpoint companion for config %d "
  				" interface %d altsetting %d ep %d: "
  				"using minimum values\n",
  				cfgno, inum, asnum, ep->desc.bEndpointAddress);
  
  		/* Fill in some default values.
  		 * Leave bmAttributes as zero, which will mean no streams for
  		 * bulk, and isoc won't support multiple bursts of packets.
  		 * With bursts of only one packet, and a Mult of 1, the max
  		 * amount of data moved per endpoint service interval is one
  		 * packet.
  		 */
  		ep->ss_ep_comp.bLength = USB_DT_SS_EP_COMP_SIZE;
  		ep->ss_ep_comp.bDescriptorType = USB_DT_SS_ENDPOINT_COMP;
  		if (usb_endpoint_xfer_isoc(&ep->desc) ||
  				usb_endpoint_xfer_int(&ep->desc))
  			ep->ss_ep_comp.wBytesPerInterval =
  					ep->desc.wMaxPacketSize;
  		return;
  	}
  
  	memcpy(&ep->ss_ep_comp, desc, USB_DT_SS_EP_COMP_SIZE);
  
  	/* Check the various values */
  	if (usb_endpoint_xfer_control(&ep->desc) && desc->bMaxBurst != 0) {
  		dev_warn(ddev, "Control endpoint with bMaxBurst = %d in "
  				"config %d interface %d altsetting %d ep %d: "
  				"setting to zero\n", desc->bMaxBurst,
  				cfgno, inum, asnum, ep->desc.bEndpointAddress);
  		ep->ss_ep_comp.bMaxBurst = 0;
  	} else if (desc->bMaxBurst > 15) {
  		dev_warn(ddev, "Endpoint with bMaxBurst = %d in "
  				"config %d interface %d altsetting %d ep %d: "
  				"setting to 15\n", desc->bMaxBurst,
  				cfgno, inum, asnum, ep->desc.bEndpointAddress);
  		ep->ss_ep_comp.bMaxBurst = 15;
  	}
  
  	if ((usb_endpoint_xfer_control(&ep->desc) ||
  			usb_endpoint_xfer_int(&ep->desc)) &&
  				desc->bmAttributes != 0) {
  		dev_warn(ddev, "%s endpoint with bmAttributes = %d in "
  				"config %d interface %d altsetting %d ep %d: "
  				"setting to zero\n",
  				usb_endpoint_xfer_control(&ep->desc) ? "Control" : "Bulk",
  				desc->bmAttributes,
  				cfgno, inum, asnum, ep->desc.bEndpointAddress);
  		ep->ss_ep_comp.bmAttributes = 0;
  	} else if (usb_endpoint_xfer_bulk(&ep->desc) &&
  			desc->bmAttributes > 16) {
  		dev_warn(ddev, "Bulk endpoint with more than 65536 streams in "
  				"config %d interface %d altsetting %d ep %d: "
  				"setting to max\n",
  				cfgno, inum, asnum, ep->desc.bEndpointAddress);
  		ep->ss_ep_comp.bmAttributes = 16;
  	} else if (usb_endpoint_xfer_isoc(&ep->desc) &&
  			desc->bmAttributes > 2) {
  		dev_warn(ddev, "Isoc endpoint has Mult of %d in "
  				"config %d interface %d altsetting %d ep %d: "
  				"setting to 3\n", desc->bmAttributes + 1,
  				cfgno, inum, asnum, ep->desc.bEndpointAddress);
  		ep->ss_ep_comp.bmAttributes = 2;
  	}
  
  	if (usb_endpoint_xfer_isoc(&ep->desc))
  		max_tx = (desc->bMaxBurst + 1) * (desc->bmAttributes + 1) *
  			usb_endpoint_maxp(&ep->desc);
  	else if (usb_endpoint_xfer_int(&ep->desc))
  		max_tx = usb_endpoint_maxp(&ep->desc) *
  			(desc->bMaxBurst + 1);
  	else
  		max_tx = 999999;
  	if (le16_to_cpu(desc->wBytesPerInterval) > max_tx) {
  		dev_warn(ddev, "%s endpoint with wBytesPerInterval of %d in "
  				"config %d interface %d altsetting %d ep %d: "
  				"setting to %d\n",
  				usb_endpoint_xfer_isoc(&ep->desc) ? "Isoc" : "Int",
  				le16_to_cpu(desc->wBytesPerInterval),
  				cfgno, inum, asnum, ep->desc.bEndpointAddress,
  				max_tx);
  		ep->ss_ep_comp.wBytesPerInterval = cpu_to_le16(max_tx);
  	}
  }
  
  static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,
      int asnum, struct usb_host_interface *ifp, int num_ep,
      unsigned char *buffer, int size)
  {
  	unsigned char *buffer0 = buffer;
  	struct usb_endpoint_descriptor *d;
  	struct usb_host_endpoint *endpoint;
  	int n, i, j, retval;
  
  	d = (struct usb_endpoint_descriptor *) buffer;
  	buffer += d->bLength;
  	size -= d->bLength;
  
  	if (d->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE)
  		n = USB_DT_ENDPOINT_AUDIO_SIZE;
  	else if (d->bLength >= USB_DT_ENDPOINT_SIZE)
  		n = USB_DT_ENDPOINT_SIZE;
  	else {
  		dev_warn(ddev, "config %d interface %d altsetting %d has an "
  		    "invalid endpoint descriptor of length %d, skipping\n",
  		    cfgno, inum, asnum, d->bLength);
  		goto skip_to_next_endpoint_or_interface_descriptor;
  	}
  
  	i = d->bEndpointAddress & ~USB_ENDPOINT_DIR_MASK;
  	if (i >= 16 || i == 0) {
  		dev_warn(ddev, "config %d interface %d altsetting %d has an "
  		    "invalid endpoint with address 0x%X, skipping\n",
  		    cfgno, inum, asnum, d->bEndpointAddress);
  		goto skip_to_next_endpoint_or_interface_descriptor;
  	}
  
  	/* Only store as many endpoints as we have room for */
  	if (ifp->desc.bNumEndpoints >= num_ep)
  		goto skip_to_next_endpoint_or_interface_descriptor;
  
  	endpoint = &ifp->endpoint[ifp->desc.bNumEndpoints];
  	++ifp->desc.bNumEndpoints;
  
  	memcpy(&endpoint->desc, d, n);
  	INIT_LIST_HEAD(&endpoint->urb_list);
  
  	/* Fix up bInterval values outside the legal range. Use 32 ms if no
  	 * proper value can be guessed. */
  	i = 0;		/* i = min, j = max, n = default */
  	j = 255;
  	if (usb_endpoint_xfer_int(d)) {
  		i = 1;
  		switch (to_usb_device(ddev)->speed) {
  		case USB_SPEED_SUPER:
  		case USB_SPEED_HIGH:
  			/* Many device manufacturers are using full-speed
  			 * bInterval values in high-speed interrupt endpoint
  			 * descriptors. Try to fix those and fall back to a
  			 * 32 ms default value otherwise. */
  			n = fls(d->bInterval*8);
  			if (n == 0)
  				n = 9;	/* 32 ms = 2^(9-1) uframes */
  			j = 16;
  			break;
  		default:		/* USB_SPEED_FULL or _LOW */
  			/* For low-speed, 10 ms is the official minimum.
  			 * But some "overclocked" devices might want faster
  			 * polling so we'll allow it. */
  			n = 32;
  			break;
  		}
  	} else if (usb_endpoint_xfer_isoc(d)) {
  		i = 1;
  		j = 16;
  		switch (to_usb_device(ddev)->speed) {
  		case USB_SPEED_HIGH:
  			n = 9;		/* 32 ms = 2^(9-1) uframes */
  			break;
  		default:		/* USB_SPEED_FULL */
  			n = 6;		/* 32 ms = 2^(6-1) frames */
  			break;
  		}
  	}
  	if (d->bInterval < i || d->bInterval > j) {
  		dev_warn(ddev, "config %d interface %d altsetting %d "
  		    "endpoint 0x%X has an invalid bInterval %d, "
  		    "changing to %d\n",
  		    cfgno, inum, asnum,
  		    d->bEndpointAddress, d->bInterval, n);
  		endpoint->desc.bInterval = n;
  	}
  
  	/* Some buggy low-speed devices have Bulk endpoints, which is
  	 * explicitly forbidden by the USB spec.  In an attempt to make
  	 * them usable, we will try treating them as Interrupt endpoints.
  	 */
  	if (to_usb_device(ddev)->speed == USB_SPEED_LOW &&
  			usb_endpoint_xfer_bulk(d)) {
  		dev_warn(ddev, "config %d interface %d altsetting %d "
  		    "endpoint 0x%X is Bulk; changing to Interrupt\n",
  		    cfgno, inum, asnum, d->bEndpointAddress);
  		endpoint->desc.bmAttributes = USB_ENDPOINT_XFER_INT;
  		endpoint->desc.bInterval = 1;
  		if (usb_endpoint_maxp(&endpoint->desc) > 8)
  			endpoint->desc.wMaxPacketSize = cpu_to_le16(8);
  	}
  
  	/*
  	 * Some buggy high speed devices have bulk endpoints using
  	 * maxpacket sizes other than 512.  High speed HCDs may not
  	 * be able to handle that particular bug, so let's warn...
  	 */
  	if (to_usb_device(ddev)->speed == USB_SPEED_HIGH
  			&& usb_endpoint_xfer_bulk(d)) {
  		unsigned maxp;
  
  		maxp = usb_endpoint_maxp(&endpoint->desc) & 0x07ff;
  		if (maxp != 512)
  			dev_warn(ddev, "config %d interface %d altsetting %d "
  				"bulk endpoint 0x%X has invalid maxpacket %d\n",
  				cfgno, inum, asnum, d->bEndpointAddress,
  				maxp);
  	}
  
  	/* Parse a possible SuperSpeed endpoint companion descriptor */
  	if (to_usb_device(ddev)->speed == USB_SPEED_SUPER)
  		usb_parse_ss_endpoint_companion(ddev, cfgno,
  				inum, asnum, endpoint, buffer, size);
  
  	/* Skip over any Class Specific or Vendor Specific descriptors;
  	 * find the next endpoint or interface descriptor */
  	endpoint->extra = buffer;
  	i = find_next_descriptor(buffer, size, USB_DT_ENDPOINT,
  			USB_DT_INTERFACE, &n);
  	endpoint->extralen = i;
  	retval = buffer - buffer0 + i;
  	if (n > 0)
  		dev_dbg(ddev, "skipped %d descriptor%s after %s\n",
  		    n, plural(n), "endpoint");
  	return retval;
  
  skip_to_next_endpoint_or_interface_descriptor:
  	i = find_next_descriptor(buffer, size, USB_DT_ENDPOINT,
  	    USB_DT_INTERFACE, NULL);
  	return buffer - buffer0 + i;
  }
  
  void usb_release_interface_cache(struct kref *ref)
  {
  	struct usb_interface_cache *intfc = ref_to_usb_interface_cache(ref);
  	int j;
  
  	for (j = 0; j < intfc->num_altsetting; j++) {
  		struct usb_host_interface *alt = &intfc->altsetting[j];
  
  		kfree(alt->endpoint);
  		kfree(alt->string);
  	}
  	kfree(intfc);
  }
  
  static int usb_parse_interface(struct device *ddev, int cfgno,
      struct usb_host_config *config, unsigned char *buffer, int size,
      u8 inums[], u8 nalts[])
  {
  	unsigned char *buffer0 = buffer;
  	struct usb_interface_descriptor	*d;
  	int inum, asnum;
  	struct usb_interface_cache *intfc;
  	struct usb_host_interface *alt;
  	int i, n;
  	int len, retval;
  	int num_ep, num_ep_orig;
  
  	d = (struct usb_interface_descriptor *) buffer;
  	buffer += d->bLength;
  	size -= d->bLength;
  
  	if (d->bLength < USB_DT_INTERFACE_SIZE)
  		goto skip_to_next_interface_descriptor;
  
  	/* Which interface entry is this? */
  	intfc = NULL;
  	inum = d->bInterfaceNumber;
  	for (i = 0; i < config->desc.bNumInterfaces; ++i) {
  		if (inums[i] == inum) {
  			intfc = config->intf_cache[i];
  			break;
  		}
  	}
  	if (!intfc || intfc->num_altsetting >= nalts[i])
  		goto skip_to_next_interface_descriptor;
  
  	/* Check for duplicate altsetting entries */
  	asnum = d->bAlternateSetting;
  	for ((i = 0, alt = &intfc->altsetting[0]);
  	      i < intfc->num_altsetting;
  	     (++i, ++alt)) {
  		if (alt->desc.bAlternateSetting == asnum) {
  			dev_warn(ddev, "Duplicate descriptor for config %d "
  			    "interface %d altsetting %d, skipping\n",
  			    cfgno, inum, asnum);
  			goto skip_to_next_interface_descriptor;
  		}
  	}
  
  	++intfc->num_altsetting;
  	memcpy(&alt->desc, d, USB_DT_INTERFACE_SIZE);
  
  	/* Skip over any Class Specific or Vendor Specific descriptors;
  	 * find the first endpoint or interface descriptor */
  	alt->extra = buffer;
  	i = find_next_descriptor(buffer, size, USB_DT_ENDPOINT,
  	    USB_DT_INTERFACE, &n);
  	alt->extralen = i;
  	if (n > 0)
  		dev_dbg(ddev, "skipped %d descriptor%s after %s\n",
  		    n, plural(n), "interface");
  	buffer += i;
  	size -= i;
  
  	/* Allocate space for the right(?) number of endpoints */
  	num_ep = num_ep_orig = alt->desc.bNumEndpoints;
  	alt->desc.bNumEndpoints = 0;		/* Use as a counter */
  	if (num_ep > USB_MAXENDPOINTS) {
  		dev_warn(ddev, "too many endpoints for config %d interface %d "
  		    "altsetting %d: %d, using maximum allowed: %d\n",
  		    cfgno, inum, asnum, num_ep, USB_MAXENDPOINTS);
  		num_ep = USB_MAXENDPOINTS;
  	}
  
  	if (num_ep > 0) {
  		/* Can't allocate 0 bytes */
  		len = sizeof(struct usb_host_endpoint) * num_ep;
  		alt->endpoint = kzalloc(len, GFP_KERNEL);
  		if (!alt->endpoint)
  			return -ENOMEM;
  	}
  
  	/* Parse all the endpoint descriptors */
  	n = 0;
  	while (size > 0) {
  		if (((struct usb_descriptor_header *) buffer)->bDescriptorType
  		     == USB_DT_INTERFACE)
  			break;
  		retval = usb_parse_endpoint(ddev, cfgno, inum, asnum, alt,
  		    num_ep, buffer, size);
  		if (retval < 0)
  			return retval;
  		++n;
  
  		buffer += retval;
  		size -= retval;
  	}
  
  	if (n != num_ep_orig)
  		dev_warn(ddev, "config %d interface %d altsetting %d has %d "
  		    "endpoint descriptor%s, different from the interface "
  		    "descriptor's value: %d\n",
  		    cfgno, inum, asnum, n, plural(n), num_ep_orig);
  	return buffer - buffer0;
  
  skip_to_next_interface_descriptor:
  	i = find_next_descriptor(buffer, size, USB_DT_INTERFACE,
  	    USB_DT_INTERFACE, NULL);
  	return buffer - buffer0 + i;
  }
  
  static int usb_parse_configuration(struct usb_device *dev, int cfgidx,
      struct usb_host_config *config, unsigned char *buffer, int size)
  {
  	struct device *ddev = &dev->dev;
  	unsigned char *buffer0 = buffer;
  	int cfgno;
  	int nintf, nintf_orig;
  	int i, j, n;
  	struct usb_interface_cache *intfc;
  	unsigned char *buffer2;
  	int size2;
  	struct usb_descriptor_header *header;
  	int len, retval;
  	u8 inums[USB_MAXINTERFACES], nalts[USB_MAXINTERFACES];
  	unsigned iad_num = 0;
  
  	memcpy(&config->desc, buffer, USB_DT_CONFIG_SIZE);
  	if (config->desc.bDescriptorType != USB_DT_CONFIG ||
  	    config->desc.bLength < USB_DT_CONFIG_SIZE ||
  	    config->desc.bLength > size) {
  		dev_err(ddev, "invalid descriptor for config index %d: "
  		    "type = 0x%X, length = %d\n", cfgidx,
  		    config->desc.bDescriptorType, config->desc.bLength);
  		return -EINVAL;
  	}
  	cfgno = config->desc.bConfigurationValue;
  
  	buffer += config->desc.bLength;
  	size -= config->desc.bLength;
  
  	nintf = nintf_orig = config->desc.bNumInterfaces;
  	if (nintf > USB_MAXINTERFACES) {
  		dev_warn(ddev, "config %d has too many interfaces: %d, "
  		    "using maximum allowed: %d\n",
  		    cfgno, nintf, USB_MAXINTERFACES);
  		nintf = USB_MAXINTERFACES;
  	}
  
  	/* Go through the descriptors, checking their length and counting the
  	 * number of altsettings for each interface */
  	n = 0;
  	for ((buffer2 = buffer, size2 = size);
  	      size2 > 0;
  	     (buffer2 += header->bLength, size2 -= header->bLength)) {
  
  		if (size2 < sizeof(struct usb_descriptor_header)) {
  			dev_warn(ddev, "config %d descriptor has %d excess "
  			    "byte%s, ignoring\n",
  			    cfgno, size2, plural(size2));
  			break;
  		}
  
  		header = (struct usb_descriptor_header *) buffer2;
  		if ((header->bLength > size2) || (header->bLength < 2)) {
  			dev_warn(ddev, "config %d has an invalid descriptor "
  			    "of length %d, skipping remainder of the config\n",
  			    cfgno, header->bLength);
  			break;
  		}
  
  		if (header->bDescriptorType == USB_DT_INTERFACE) {
  			struct usb_interface_descriptor *d;
  			int inum;
  
  			d = (struct usb_interface_descriptor *) header;
  			if (d->bLength < USB_DT_INTERFACE_SIZE) {
  				dev_warn(ddev, "config %d has an invalid "
  				    "interface descriptor of length %d, "
  				    "skipping\n", cfgno, d->bLength);
  				continue;
  			}
  
  			inum = d->bInterfaceNumber;
  
  			if ((dev->quirks & USB_QUIRK_HONOR_BNUMINTERFACES) &&
  			    n >= nintf_orig) {
  				dev_warn(ddev, "config %d has more interface "
  				    "descriptors, than it declares in "
  				    "bNumInterfaces, ignoring interface "
  				    "number: %d\n", cfgno, inum);
  				continue;
  			}
  
  			if (inum >= nintf_orig)
  				dev_warn(ddev, "config %d has an invalid "
  				    "interface number: %d but max is %d\n",
  				    cfgno, inum, nintf_orig - 1);
  
  			/* Have we already encountered this interface?
  			 * Count its altsettings */
  			for (i = 0; i < n; ++i) {
  				if (inums[i] == inum)
  					break;
  			}
  			if (i < n) {
  				if (nalts[i] < 255)
  					++nalts[i];
  			} else if (n < USB_MAXINTERFACES) {
  				inums[n] = inum;
  				nalts[n] = 1;
  				++n;
  			}
  
  		} else if (header->bDescriptorType ==
  				USB_DT_INTERFACE_ASSOCIATION) {
  			if (iad_num == USB_MAXIADS) {
  				dev_warn(ddev, "found more Interface "
  					       "Association Descriptors "
  					       "than allocated for in "
  					       "configuration %d\n", cfgno);
  			} else {
  				config->intf_assoc[iad_num] =
  					(struct usb_interface_assoc_descriptor
  					*)header;
  				iad_num++;
  			}
  
  		} else if (header->bDescriptorType == USB_DT_DEVICE ||
  			    header->bDescriptorType == USB_DT_CONFIG)
  			dev_warn(ddev, "config %d contains an unexpected "
  			    "descriptor of type 0x%X, skipping\n",
  			    cfgno, header->bDescriptorType);
  
  	}	/* for ((buffer2 = buffer, size2 = size); ...) */
  	size = buffer2 - buffer;
  	config->desc.wTotalLength = cpu_to_le16(buffer2 - buffer0);
  
  	if (n != nintf)
  		dev_warn(ddev, "config %d has %d interface%s, different from "
  		    "the descriptor's value: %d\n",
  		    cfgno, n, plural(n), nintf_orig);
  	else if (n == 0)
  		dev_warn(ddev, "config %d has no interfaces?\n", cfgno);
  	config->desc.bNumInterfaces = nintf = n;
  
  	/* Check for missing interface numbers */
  	for (i = 0; i < nintf; ++i) {
  		for (j = 0; j < nintf; ++j) {
  			if (inums[j] == i)
  				break;
  		}
  		if (j >= nintf)
  			dev_warn(ddev, "config %d has no interface number "
  			    "%d\n", cfgno, i);
  	}
  
  	/* Allocate the usb_interface_caches and altsetting arrays */
  	for (i = 0; i < nintf; ++i) {
  		j = nalts[i];
  		if (j > USB_MAXALTSETTING) {
  			dev_warn(ddev, "too many alternate settings for "
  			    "config %d interface %d: %d, "
  			    "using maximum allowed: %d\n",
  			    cfgno, inums[i], j, USB_MAXALTSETTING);
  			nalts[i] = j = USB_MAXALTSETTING;
  		}
  
  		len = sizeof(*intfc) + sizeof(struct usb_host_interface) * j;
  		config->intf_cache[i] = intfc = kzalloc(len, GFP_KERNEL);
  		if (!intfc)
  			return -ENOMEM;
  		kref_init(&intfc->ref);
  	}
  
  	/* FIXME: parse the BOS descriptor */
  
  	/* Skip over any Class Specific or Vendor Specific descriptors;
  	 * find the first interface descriptor */
  	config->extra = buffer;
  	i = find_next_descriptor(buffer, size, USB_DT_INTERFACE,
  	    USB_DT_INTERFACE, &n);
  	config->extralen = i;
  	if (n > 0)
  		dev_dbg(ddev, "skipped %d descriptor%s after %s\n",
  		    n, plural(n), "configuration");
  	buffer += i;
  	size -= i;
  
  	/* Parse all the interface/altsetting descriptors */
  	while (size > 0) {
  		retval = usb_parse_interface(ddev, cfgno, config,
  		    buffer, size, inums, nalts);
  		if (retval < 0)
  			return retval;
  
  		buffer += retval;
  		size -= retval;
  	}
  
  	/* Check for missing altsettings */
  	for (i = 0; i < nintf; ++i) {
  		intfc = config->intf_cache[i];
  		for (j = 0; j < intfc->num_altsetting; ++j) {
  			for (n = 0; n < intfc->num_altsetting; ++n) {
  				if (intfc->altsetting[n].desc.
  				    bAlternateSetting == j)
  					break;
  			}
  			if (n >= intfc->num_altsetting)
  				dev_warn(ddev, "config %d interface %d has no "
  				    "altsetting %d\n", cfgno, inums[i], j);
  		}
  	}
  
  	return 0;
  }
  
  /* hub-only!! ... and only exported for reset/reinit path.
   * otherwise used internally on disconnect/destroy path
   */
  void usb_destroy_configuration(struct usb_device *dev)
  {
  	int c, i;
  
  	if (!dev->config)
  		return;
  
  	if (dev->rawdescriptors) {
  		for (i = 0; i < dev->descriptor.bNumConfigurations; i++)
  			kfree(dev->rawdescriptors[i]);
  
  		kfree(dev->rawdescriptors);
  		dev->rawdescriptors = NULL;
  	}
  
  	for (c = 0; c < dev->descriptor.bNumConfigurations; c++) {
  		struct usb_host_config *cf = &dev->config[c];
  
  		kfree(cf->string);
  		for (i = 0; i < cf->desc.bNumInterfaces; i++) {
  			if (cf->intf_cache[i])
  				kref_put(&cf->intf_cache[i]->ref,
  					  usb_release_interface_cache);
  		}
  	}
  	kfree(dev->config);
  	dev->config = NULL;
  }
  
  
  /*
   * Get the USB config descriptors, cache and parse'em
   *
   * hub-only!! ... and only in reset path, or usb_new_device()
   * (used by real hubs and virtual root hubs)
   */
  int usb_get_configuration(struct usb_device *dev)
  {
  	struct device *ddev = &dev->dev;
  	int ncfg = dev->descriptor.bNumConfigurations;
  	int result = 0;
  	unsigned int cfgno, length;
  	unsigned char *bigbuffer;
  	struct usb_config_descriptor *desc;
  
  	cfgno = 0;
  	result = -ENOMEM;
  	if (ncfg > USB_MAXCONFIG) {
  		dev_warn(ddev, "too many configurations: %d, "
  		    "using maximum allowed: %d\n", ncfg, USB_MAXCONFIG);
  		dev->descriptor.bNumConfigurations = ncfg = USB_MAXCONFIG;
  	}
  
  	if (ncfg < 1) {
  		dev_err(ddev, "no configurations\n");
  		return -EINVAL;
  	}
  
  	length = ncfg * sizeof(struct usb_host_config);
  	dev->config = kzalloc(length, GFP_KERNEL);
  	if (!dev->config)
  		goto err2;
  
  	length = ncfg * sizeof(char *);
  	dev->rawdescriptors = kzalloc(length, GFP_KERNEL);
  	if (!dev->rawdescriptors)
  		goto err2;
  
  	desc = kmalloc(USB_DT_CONFIG_SIZE, GFP_KERNEL);
  	if (!desc)
  		goto err2;
  
  	result = 0;
  	for (; cfgno < ncfg; cfgno++) {
  		/* We grab just the first descriptor so we know how long
  		 * the whole configuration is */
  		result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno,
  		    desc, USB_DT_CONFIG_SIZE);
  		if (result < 0) {
  			dev_err(ddev, "unable to read config index %d "
  			    "descriptor/%s: %d\n", cfgno, "start", result);
  			if (result != -EPIPE)
  				goto err;
  			dev_err(ddev, "chopping to %d config(s)\n", cfgno);
  			dev->descriptor.bNumConfigurations = cfgno;
  			break;
  		} else if (result < 4) {
  			dev_err(ddev, "config index %d descriptor too short "
  			    "(expected %i, got %i)\n", cfgno,
  			    USB_DT_CONFIG_SIZE, result);
  			result = -EINVAL;
  			goto err;
  		}
  		length = max((int) le16_to_cpu(desc->wTotalLength),
  		    USB_DT_CONFIG_SIZE);
  
  		/* Now that we know the length, get the whole thing */
  		bigbuffer = kmalloc(length, GFP_KERNEL);
  		if (!bigbuffer) {
  			result = -ENOMEM;
  			goto err;
  		}
  
  		if (dev->quirks & USB_QUIRK_DELAY_INIT)
  			msleep(100);
  
  		result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno,
  		    bigbuffer, length);
  		if (result < 0) {
  			dev_err(ddev, "unable to read config index %d "
  			    "descriptor/%s\n", cfgno, "all");
  			kfree(bigbuffer);
  			goto err;
  		}
  		if (result < length) {
  			dev_warn(ddev, "config index %d descriptor too short "
  			    "(expected %i, got %i)\n", cfgno, length, result);
  			length = result;
  		}
  
  		dev->rawdescriptors[cfgno] = bigbuffer;
  
  		result = usb_parse_configuration(dev, cfgno,
  		    &dev->config[cfgno], bigbuffer, length);
  		if (result < 0) {
  			++cfgno;
  			goto err;
  		}
  	}
  	result = 0;
  
  err:
  	kfree(desc);
  	dev->descriptor.bNumConfigurations = cfgno;
  err2:
  	if (result == -ENOMEM)
  		dev_err(ddev, "out of memory\n");
  	return result;
  }
  
  void usb_release_bos_descriptor(struct usb_device *dev)
  {
  	if (dev->bos) {
  		kfree(dev->bos->desc);
  		kfree(dev->bos);
  		dev->bos = NULL;
  	}
  }
  
  /* Get BOS descriptor set */
  int usb_get_bos_descriptor(struct usb_device *dev)
  {
  	struct device *ddev = &dev->dev;
  	struct usb_bos_descriptor *bos;
  	struct usb_dev_cap_header *cap;
  	unsigned char *buffer;
  	int length, total_len, num, i;
  	int ret;
  
  	bos = kzalloc(sizeof(struct usb_bos_descriptor), GFP_KERNEL);
  	if (!bos)
  		return -ENOMEM;
  
  	/* Get BOS descriptor */
  	ret = usb_get_descriptor(dev, USB_DT_BOS, 0, bos, USB_DT_BOS_SIZE);
  	if (ret < USB_DT_BOS_SIZE) {
  		dev_err(ddev, "unable to get BOS descriptor\n");
  		if (ret >= 0)
  			ret = -ENOMSG;
  		kfree(bos);
  		return ret;
  	}
  
  	length = bos->bLength;
  	total_len = le16_to_cpu(bos->wTotalLength);
  	num = bos->bNumDeviceCaps;
  	kfree(bos);
  	if (total_len < length)
  		return -EINVAL;
  
  	dev->bos = kzalloc(sizeof(struct usb_host_bos), GFP_KERNEL);
  	if (!dev->bos)
  		return -ENOMEM;
  
  	/* Now let's get the whole BOS descriptor set */
  	buffer = kzalloc(total_len, GFP_KERNEL);
  	if (!buffer) {
  		ret = -ENOMEM;
  		goto err;
  	}
  	dev->bos->desc = (struct usb_bos_descriptor *)buffer;
  
  	ret = usb_get_descriptor(dev, USB_DT_BOS, 0, buffer, total_len);
  	if (ret < total_len) {
  		dev_err(ddev, "unable to get BOS descriptor set\n");
  		if (ret >= 0)
  			ret = -ENOMSG;
  		goto err;
  	}
  	total_len -= length;
  
  	for (i = 0; i < num; i++) {
  		buffer += length;
  		cap = (struct usb_dev_cap_header *)buffer;
  		length = cap->bLength;
  
  		if (total_len < length)
  			break;
  		total_len -= length;
  
  		if (cap->bDescriptorType != USB_DT_DEVICE_CAPABILITY) {
  			dev_warn(ddev, "descriptor type invalid, skip\n");
  			continue;
  		}
  
  		switch (cap->bDevCapabilityType) {
  		case USB_CAP_TYPE_WIRELESS_USB:
  			/* Wireless USB cap descriptor is handled by wusb */
  			break;
  		case USB_CAP_TYPE_EXT:
  			dev->bos->ext_cap =
  				(struct usb_ext_cap_descriptor *)buffer;
  			break;
  		case USB_SS_CAP_TYPE:
  			dev->bos->ss_cap =
  				(struct usb_ss_cap_descriptor *)buffer;
  			break;
  		case CONTAINER_ID_TYPE:
  			dev->bos->ss_id =
  				(struct usb_ss_container_id_descriptor *)buffer;
  			break;
  		default:
  			break;
  		}
  	}
  
  	return 0;
  
  err:
  	usb_release_bos_descriptor(dev);
  	return ret;
  }
  