LXR linux/drivers/usb/gadget/config.c

   1/*
   2 * usb/gadget/config.c -- simplify building config descriptors
   3 *
   4 * Copyright (C) 2003 David Brownell
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program; if not, write to the Free Software
  18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19 */
  20
  21#include <linux/errno.h>
  22#include <linux/kernel.h>
  23#include <linux/list.h>
  24#include <linux/string.h>
  25#include <linux/device.h>
  26
  27#include <linux/usb/ch9.h>
  28#include <linux/usb/gadget.h>
  29
  30
  31/**
  32 * usb_descriptor_fillbuf - fill buffer with descriptors
  33 * @buf: Buffer to be filled
  34 * @buflen: Size of buf
  35 * @src: Array of descriptor pointers, terminated by null pointer.
  36 *
  37 * Copies descriptors into the buffer, returning the length or a
  38 * negative error code if they can't all be copied.  Useful when
  39 * assembling descriptors for an associated set of interfaces used
  40 * as part of configuring a composite device; or in other cases where
  41 * sets of descriptors need to be marshaled.
  42 */
  43int
  44usb_descriptor_fillbuf(void *buf, unsigned buflen,
  45                const struct usb_descriptor_header **src)
  46{
  47        u8      *dest = buf;
  48
  49        if (!src)
  50                return -EINVAL;
  51
  52        /* fill buffer from src[] until null descriptor ptr */
  53        for (; NULL != *src; src++) {
  54                unsigned                len = (*src)->bLength;
  55
  56                if (len > buflen)
  57                        return -EINVAL;
  58                memcpy(dest, *src, len);
  59                buflen -= len;
  60                dest += len;
  61        }
  62        return dest - (u8 *)buf;
  63}
  64
  65
  66/**
  67 * usb_gadget_config_buf - builts a complete configuration descriptor
  68 * @config: Header for the descriptor, including characteristics such
  69 *      as power requirements and number of interfaces.
  70 * @desc: Null-terminated vector of pointers to the descriptors (interface,
  71 *      endpoint, etc) defining all functions in this device configuration.
  72 * @buf: Buffer for the resulting configuration descriptor.
  73 * @length: Length of buffer.  If this is not big enough to hold the
  74 *      entire configuration descriptor, an error code will be returned.
  75 *
  76 * This copies descriptors into the response buffer, building a descriptor
  77 * for that configuration.  It returns the buffer length or a negative
  78 * status code.  The config.wTotalLength field is set to match the length
  79 * of the result, but other descriptor fields (including power usage and
  80 * interface count) must be set by the caller.
  81 *
  82 * Gadget drivers could use this when constructing a config descriptor
  83 * in response to USB_REQ_GET_DESCRIPTOR.  They will need to patch the
  84 * resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
  85 */
  86int usb_gadget_config_buf(
  87        const struct usb_config_descriptor      *config,
  88        void                                    *buf,
  89        unsigned                                length,
  90        const struct usb_descriptor_header      **desc
  91)
  92{
  93        struct usb_config_descriptor            *cp = buf;
  94        int                                     len;
  95
  96        /* config descriptor first */
  97        if (length < USB_DT_CONFIG_SIZE || !desc)
  98                return -EINVAL;
  99        *cp = *config; 
 100
 101        /* then interface/endpoint/class/vendor/... */
 102        len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8*)buf,
 103                        length - USB_DT_CONFIG_SIZE, desc);
 104        if (len < 0)
 105                return len;
 106        len += USB_DT_CONFIG_SIZE;
 107        if (len > 0xffff)
 108                return -EINVAL;
 109
 110        /* patch up the config descriptor */
 111        cp->bLength = USB_DT_CONFIG_SIZE;
 112        cp->bDescriptorType = USB_DT_CONFIG;
 113        cp->wTotalLength = cpu_to_le16(len);
 114        cp->bmAttributes |= USB_CONFIG_ATT_ONE;
 115        return len;
 116}
 117
 118