blob: 014a6791c17139e5cc04830ab576f304a0b51392 [file] [log] [blame]
* usb/gadget/config.c -- simplify building config descriptors
* Copyright (C) 2003 David Brownell
* SPDX-License-Identifier: GPL-2.0+
* Ported to U-boot by: Thomas Smits <> and
* Remy Bohmer <>
#include <common.h>
#include <asm/unaligned.h>
#include <asm/errno.h>
#include <linux/list.h>
#include <linux/string.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.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.
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_gadget_config_buf - builts a complete configuration descriptor
* @config: Header for the descriptor, including characteristics such
* as power requirements and number of interfaces.
* @desc: Null-terminated vector of pointers to the descriptors (interface,
* endpoint, etc) defining all functions in this device configuration.
* @buf: Buffer for the resulting configuration descriptor.
* @length: Length of buffer. If this is not big enough to hold the
* entire configuration descriptor, an error code will be returned.
* This copies descriptors into the response buffer, building a descriptor
* for that configuration. It returns the buffer length or a negative
* status code. The config.wTotalLength field is set to match the length
* of the result, but other descriptor fields (including power usage and
* interface count) must be set by the caller.
* Gadget drivers could use this when constructing a config descriptor
* in response to USB_REQ_GET_DESCRIPTOR. They will need to patch the
* resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
int usb_gadget_config_buf(
const struct usb_config_descriptor *config,
void *buf,
unsigned length,
const struct usb_descriptor_header **desc
struct usb_config_descriptor *cp = buf;
int len;
/* config descriptor first */
if (length < USB_DT_CONFIG_SIZE || !desc)
return -EINVAL;
/* config need not be aligned */
memcpy(cp, config, sizeof(*cp));
/* then interface/endpoint/class/vendor/... */
len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8 *)buf,
length - USB_DT_CONFIG_SIZE, desc);
if (len < 0)
return len;
if (len > 0xffff)
return -EINVAL;
/* patch up the config descriptor */
cp->bLength = USB_DT_CONFIG_SIZE;
cp->bDescriptorType = USB_DT_CONFIG;
put_unaligned_le16(len, &cp->wTotalLength);
cp->bmAttributes |= USB_CONFIG_ATT_ONE;
return len;