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/slab.h>
  23 #include <linux/kernel.h>
  24 #include <linux/list.h>
  25 #include <linux/string.h>
  26 #include <linux/device.h>
  27
  28 #include <linux/usb/ch9.h>
  29 #include <linux/usb/gadget.h>
  30
  31
  32 /**
  33  * usb_descriptor_fillbuf - fill buffer with descriptors
  34  * @buf: Buffer to be filled
  35  * @buflen: Size of buf
  36  * @src: Array of descriptor pointers, terminated by null pointer.
  37  *
  38  * Copies descriptors into the buffer, returning the length or a
  39  * negative error code if they can't all be copied.  Useful when
  40  * assembling descriptors for an associated set of interfaces used
  41  * as part of configuring a composite device; or in other cases where
  42  * sets of descriptors need to be marshaled.
  43  */
  44 int
  45 usb_descriptor_fillbuf(void *buf, unsigned buflen,
  46                 const struct usb_descriptor_header **src)
  47 {
  48         u8      *dest = buf;
  49
  50         if (!src)
  51                 return -EINVAL;
  52
  53         /* fill buffer from src[] until null descriptor ptr */
  54         for (; NULL != *src; src++) {
  55                 unsigned                len = (*src)->bLength;
  56
  57                 if (len > buflen)
  58                         return -EINVAL;
  59                 memcpy(dest, *src, len);
  60                 buflen -= len;
  61                 dest += len;
  62         }
  63         return dest - (u8 *)buf;
  64 }
  65
  66
  67 /**
  68  * usb_gadget_config_buf - builts a complete configuration descriptor
  69  * @config: Header for the descriptor, including characteristics such
  70  *      as power requirements and number of interfaces.
  71  * @desc: Null-terminated vector of pointers to the descriptors (interface,
  72  *      endpoint, etc) defining all functions in this device configuration.
  73  * @buf: Buffer for the resulting configuration descriptor.
  74  * @length: Length of buffer.  If this is not big enough to hold the
  75  *      entire configuration descriptor, an error code will be returned.
  76  *
  77  * This copies descriptors into the response buffer, building a descriptor
  78  * for that configuration.  It returns the buffer length or a negative
  79  * status code.  The config.wTotalLength field is set to match the length
  80  * of the result, but other descriptor fields (including power usage and
  81  * interface count) must be set by the caller.
  82  *
  83  * Gadget drivers could use this when constructing a config descriptor
  84  * in response to USB_REQ_GET_DESCRIPTOR.  They will need to patch the
  85  * resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
  86  */
  87 int usb_gadget_config_buf(
  88         const struct usb_config_descriptor      *config,
  89         void                                    *buf,
  90         unsigned                                length,
  91         const struct usb_descriptor_header      **desc
  92 )
  93 {
  94         struct usb_config_descriptor            *cp = buf;
  95         int                                     len;
  96
  97         /* config descriptor first */
  98         if (length < USB_DT_CONFIG_SIZE || !desc)
  99                 return -EINVAL;
 100         *cp = *config;
 101
 102         /* then interface/endpoint/class/vendor/... */
 103         len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8*)buf,
 104                         length - USB_DT_CONFIG_SIZE, desc);
 105         if (len < 0)
 106                 return len;
 107         len += USB_DT_CONFIG_SIZE;
 108         if (len > 0xffff)
 109                 return -EINVAL;
 110
 111         /* patch up the config descriptor */
 112         cp->bLength = USB_DT_CONFIG_SIZE;
 113         cp->bDescriptorType = USB_DT_CONFIG;
 114         cp->wTotalLength = cpu_to_le16(len);
 115         cp->bmAttributes |= USB_CONFIG_ATT_ONE;
 116         return len;
 117 }
 118
 119 /**
 120  * usb_copy_descriptors - copy a vector of USB descriptors
 121  * @src: null-terminated vector to copy
 122  * Context: initialization code, which may sleep
 123  *
 124  * This makes a copy of a vector of USB descriptors.  Its primary use
 125  * is to support usb_function objects which can have multiple copies,
 126  * each needing different descriptors.  Functions may have static
 127  * tables of descriptors, which are used as templates and customized
 128  * with identifiers (for interfaces, strings, endpoints, and more)
 129  * as needed by a given function instance.
 130  */
 131 struct usb_descriptor_header **
 132 usb_copy_descriptors(struct usb_descriptor_header **src)
 133 {
 134         struct usb_descriptor_header **tmp;
 135         unsigned bytes;
 136         unsigned n_desc;
 137         void *mem;
 138         struct usb_descriptor_header **ret;
 139
 140         /* count descriptors and their sizes; then add vector size */
 141         for (bytes = 0, n_desc = 0, tmp = src; *tmp; tmp++, n_desc++)
 142                 bytes += (*tmp)->bLength;
 143         bytes += (n_desc + 1) * sizeof(*tmp);
 144
 145         mem = kmalloc(bytes, GFP_KERNEL);
 146         if (!mem)
 147                 return NULL;
 148
 149         /* fill in pointers starting at "tmp",
 150          * to descriptors copied starting at "mem";
 151          * and return "ret"
 152          */
 153         tmp = mem;
 154         ret = mem;
 155         mem += (n_desc + 1) * sizeof(*tmp);
 156         while (*src) {
 157                 memcpy(mem, *src, (*src)->bLength);
 158                 *tmp = mem;
 159                 tmp++;
 160                 mem += (*src)->bLength;
 161                 src++;
 162         }
 163         *tmp = NULL;
 164
 165         return ret;
 166 }
 167