blob: 83b4866df9af0919c3f60abd90b38c7bc94385fc [file] [log] [blame]
* usb/gadget/config.c -- simplify building config descriptors
* Copyright (C) 2003 David Brownell
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/string.h>
#include <linux/device.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 (; 0 != *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;
*cp = *config;
/* 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;
cp->wTotalLength = cpu_to_le16(len);
cp->bmAttributes |= USB_CONFIG_ATT_ONE;
return len;