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
  12 #include <linux/errno.h>
  13 #include <linux/slab.h>
  14 #include <linux/kernel.h>
  15 #include <linux/list.h>
  16 #include <linux/string.h>
  17 #include <linux/device.h>
  18
  19 #include <linux/usb/ch9.h>
  20 #include <linux/usb/gadget.h>
  21
  22
  23 /**
  24  * usb_descriptor_fillbuf - fill buffer with descriptors
  25  * @buf: Buffer to be filled
  26  * @buflen: Size of buf
  27  * @src: Array of descriptor pointers, terminated by null pointer.
  28  *
  29  * Copies descriptors into the buffer, returning the length or a
  30  * negative error code if they can't all be copied.  Useful when
  31  * assembling descriptors for an associated set of interfaces used
  32  * as part of configuring a composite device; or in other cases where
  33  * sets of descriptors need to be marshaled.
  34  */
  35 int
  36 usb_descriptor_fillbuf(void *buf, unsigned buflen,
  37                 const struct usb_descriptor_header **src)
  38 {
  39         u8      *dest = buf;
  40
  41         if (!src)
  42                 return -EINVAL;
  43
  44         /* fill buffer from src[] until null descriptor ptr */
  45         for (; NULL != *src; src++) {
  46                 unsigned                len = (*src)->bLength;
  47
  48                 if (len > buflen)
  49                         return -EINVAL;
  50                 memcpy(dest, *src, len);
  51                 buflen -= len;
  52                 dest += len;
  53         }
  54         return dest - (u8 *)buf;
  55 }
  56
  57
  58 /**
  59  * usb_gadget_config_buf - builts a complete configuration descriptor
  60  * @config: Header for the descriptor, including characteristics such
  61  *      as power requirements and number of interfaces.
  62  * @desc: Null-terminated vector of pointers to the descriptors (interface,
  63  *      endpoint, etc) defining all functions in this device configuration.
  64  * @buf: Buffer for the resulting configuration descriptor.
  65  * @length: Length of buffer.  If this is not big enough to hold the
  66  *      entire configuration descriptor, an error code will be returned.
  67  *
  68  * This copies descriptors into the response buffer, building a descriptor
  69  * for that configuration.  It returns the buffer length or a negative
  70  * status code.  The config.wTotalLength field is set to match the length
  71  * of the result, but other descriptor fields (including power usage and
  72  * interface count) must be set by the caller.
  73  *
  74  * Gadget drivers could use this when constructing a config descriptor
  75  * in response to USB_REQ_GET_DESCRIPTOR.  They will need to patch the
  76  * resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
  77  */
  78 int usb_gadget_config_buf(
  79         const struct usb_config_descriptor      *config,
  80         void                                    *buf,
  81         unsigned                                length,
  82         const struct usb_descriptor_header      **desc
  83 )
  84 {
  85         struct usb_config_descriptor            *cp = buf;
  86         int                                     len;
  87
  88         /* config descriptor first */
  89         if (length < USB_DT_CONFIG_SIZE || !desc)
  90                 return -EINVAL;
  91         *cp = *config;
  92
  93         /* then interface/endpoint/class/vendor/... */
  94         len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8*)buf,
  95                         length - USB_DT_CONFIG_SIZE, desc);
  96         if (len < 0)
  97                 return len;
  98         len += USB_DT_CONFIG_SIZE;
  99         if (len > 0xffff)
 100                 return -EINVAL;
 101
 102         /* patch up the config descriptor */
 103         cp->bLength = USB_DT_CONFIG_SIZE;
 104         cp->bDescriptorType = USB_DT_CONFIG;
 105         cp->wTotalLength = cpu_to_le16(len);
 106         cp->bmAttributes |= USB_CONFIG_ATT_ONE;
 107         return len;
 108 }
 109
 110 /**
 111  * usb_copy_descriptors - copy a vector of USB descriptors
 112  * @src: null-terminated vector to copy
 113  * Context: initialization code, which may sleep
 114  *
 115  * This makes a copy of a vector of USB descriptors.  Its primary use
 116  * is to support usb_function objects which can have multiple copies,
 117  * each needing different descriptors.  Functions may have static
 118  * tables of descriptors, which are used as templates and customized
 119  * with identifiers (for interfaces, strings, endpoints, and more)
 120  * as needed by a given function instance.
 121  */
 122 struct usb_descriptor_header **
 123 usb_copy_descriptors(struct usb_descriptor_header **src)
 124 {
 125         struct usb_descriptor_header **tmp;
 126         unsigned bytes;
 127         unsigned n_desc;
 128         void *mem;
 129         struct usb_descriptor_header **ret;
 130
 131         /* count descriptors and their sizes; then add vector size */
 132         for (bytes = 0, n_desc = 0, tmp = src; *tmp; tmp++, n_desc++)
 133                 bytes += (*tmp)->bLength;
 134         bytes += (n_desc + 1) * sizeof(*tmp);
 135
 136         mem = kmalloc(bytes, GFP_KERNEL);
 137         if (!mem)
 138                 return NULL;
 139
 140         /* fill in pointers starting at "tmp",
 141          * to descriptors copied starting at "mem";
 142          * and return "ret"
 143          */
 144         tmp = mem;
 145         ret = mem;
 146         mem += (n_desc + 1) * sizeof(*tmp);
 147         while (*src) {
 148                 memcpy(mem, *src, (*src)->bLength);
 149                 *tmp = mem;
 150                 tmp++;
 151                 mem += (*src)->bLength;
 152                 src++;
 153         }
 154         *tmp = NULL;
 155
 156         return ret;
 157 }
 158