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  */
  43 int
  44 usb_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  */
  86 int 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 /**
 119  * usb_copy_descriptors - copy a vector of USB descriptors
 120  * @src: null-terminated vector to copy
 121  * Context: initialization code, which may sleep
 122  *
 123  * This makes a copy of a vector of USB descriptors.  Its primary use
 124  * is to support usb_function objects which can have multiple copies,
 125  * each needing different descriptors.  Functions may have static
 126  * tables of descriptors, which are used as templates and customized
 127  * with identifiers (for interfaces, strings, endpoints, and more)
 128  * as needed by a given function instance.
 129  */
 130 struct usb_descriptor_header **__init
 131 usb_copy_descriptors(struct usb_descriptor_header **src)
 132 {
 133         struct usb_descriptor_header **tmp;
 134         unsigned bytes;
 135         unsigned n_desc;
 136         void *mem;
 137         struct usb_descriptor_header **ret;
 138
 139         /* count descriptors and their sizes; then add vector size */
 140         for (bytes = 0, n_desc = 0, tmp = src; *tmp; tmp++, n_desc++)
 141                 bytes += (*tmp)->bLength;
 142         bytes += (n_desc + 1) * sizeof(*tmp);
 143
 144         mem = kmalloc(bytes, GFP_KERNEL);
 145         if (!mem)
 146                 return NULL;
 147
 148         /* fill in pointers starting at "tmp",
 149          * to descriptors copied starting at "mem";
 150          * and return "ret"
 151          */
 152         tmp = mem;
 153         ret = mem;
 154         mem += (n_desc + 1) * sizeof(*tmp);
 155         while (*src) {
 156                 memcpy(mem, *src, (*src)->bLength);
 157                 *tmp = mem;
 158                 tmp++;
 159                 mem += (*src)->bLength;
 160                 src++;
 161         }
 162         *tmp = NULL;
 163
 164         return ret;
 165 }
 166
 167 /**
 168  * usb_find_endpoint - find a copy of an endpoint descriptor
 169  * @src: original vector of descriptors
 170  * @copy: copy of @src
 171  * @match: endpoint descriptor found in @src
 172  *
 173  * This returns the copy of the @match descriptor made for @copy.  Its
 174  * intended use is to help remembering the endpoint descriptor to use
 175  * when enabling a given endpoint.
 176  */
 177 struct usb_endpoint_descriptor *__init
 178 usb_find_endpoint(
 179         struct usb_descriptor_header **src,
 180         struct usb_descriptor_header **copy,
 181         struct usb_endpoint_descriptor *match
 182 )
 183 {
 184         while (*src) {
 185                 if (*src == (void *) match)
 186                         return (void *)*copy;
 187                 src++;
 188                 copy++;
 189         }
 190         return NULL;
 191 }