drivers/usb/gadget/config.c

#include <common.h>
#include <malloc.h>
#include <errno.h>
#include <usb/ch9.h>

/**
 * usb_descriptor_fillbuf - fill buffer with descriptors
 * @buf: Buffer to be filled
 * @buflen: Size of buf
 * @src: Array of descriptor pointers, terminated by null pointer.
 *
 * Copies descriptors into the buffer, returning the length or a
 * negative error code if they can't all be copied.  Useful when
 * assembling descriptors for an associated set of interfaces used
 * as part of configuring a composite device; or in other cases where
 * sets of descriptors need to be marshaled.
 */
int
usb_descriptor_fillbuf(void *buf, unsigned buflen,
		const struct usb_descriptor_header **src)
{
	u8	*dest = buf;

	if (!src)
		return -EINVAL;

	/* fill buffer from src[] until null descriptor ptr */
	for (; NULL != *src; src++) {
		unsigned		len = (*src)->bLength;

		if (len > buflen)
			return -EINVAL;
		memcpy(dest, *src, len);
		buflen -= len;
		dest += len;
	}
	return dest - (u8 *)buf;
}

/**
 * usb_copy_descriptors - copy a vector of USB descriptors
 * @src: null-terminated vector to copy
 * Context: initialization code, which may sleep
 *
 * This makes a copy of a vector of USB descriptors.  Its primary use
 * is to support usb_function objects which can have multiple copies,
 * each needing different descriptors.  Functions may have static
 * tables of descriptors, which are used as templates and customized
 * with identifiers (for interfaces, strings, endpoints, and more)
 * as needed by a given function instance.
 */
struct usb_descriptor_header **__init
usb_copy_descriptors(struct usb_descriptor_header **src)
{
	struct usb_descriptor_header **tmp;
	unsigned bytes;
	unsigned n_desc;
	void *mem;
	struct usb_descriptor_header **ret;

	/* count descriptors and their sizes; then add vector size */
	for (bytes = 0, n_desc = 0, tmp = src; *tmp; tmp++, n_desc++)
		bytes += (*tmp)->bLength;
	bytes += (n_desc + 1) * sizeof(*tmp);

	mem = kmalloc(bytes, GFP_KERNEL);
	if (!mem)
		return NULL;

	/* fill in pointers starting at "tmp",
	 * to descriptors copied starting at "mem";
	 * and return "ret"
	 */
	tmp = mem;
	ret = mem;
	mem += (n_desc + 1) * sizeof(*tmp);
	while (*src) {
		memcpy(mem, *src, (*src)->bLength);
		*tmp = mem;
		tmp++;
		mem += (*src)->bLength;
		src++;
	}
	*tmp = NULL;

	return ret;
}

/**
 * usb_find_endpoint - find a copy of an endpoint descriptor
 * @src: original vector of descriptors
 * @copy: copy of @src
 * @match: endpoint descriptor found in @src
 *
 * This returns the copy of the @match descriptor made for @copy.  Its
 * intended use is to help remembering the endpoint descriptor to use
 * when enabling a given endpoint.
 */
struct usb_endpoint_descriptor *__init
usb_find_endpoint(
	struct usb_descriptor_header **src,
	struct usb_descriptor_header **copy,
	struct usb_endpoint_descriptor *match
)
{
	while (*src) {
		if (*src == (void *) match)
			return (void *)*copy;
		src++;
		copy++;
	}
	return NULL;
}