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/module.h>
  16 #include <linux/list.h>
  17 #include <linux/string.h>
  18 #include <linux/device.h>
  19
  20 #include <linux/usb/ch9.h>
  21 #include <linux/usb/gadget.h>
  22 #include <linux/usb/composite.h>
  23
  24 /**
  25  * usb_descriptor_fillbuf - fill buffer with descriptors
  26  * @buf: Buffer to be filled
  27  * @buflen: Size of buf
  28  * @src: Array of descriptor pointers, terminated by null pointer.
  29  *
  30  * Copies descriptors into the buffer, returning the length or a
  31  * negative error code if they can't all be copied.  Useful when
  32  * assembling descriptors for an associated set of interfaces used
  33  * as part of configuring a composite device; or in other cases where
  34  * sets of descriptors need to be marshaled.
  35  */
  36 int
  37 usb_descriptor_fillbuf(void *buf, unsigned buflen,
  38                 const struct usb_descriptor_header **src)
  39 {
  40         u8      *dest = buf;
  41
  42         if (!src)
  43                 return -EINVAL;
  44
  45         /* fill buffer from src[] until null descriptor ptr */
  46         for (; NULL != *src; src++) {
  47                 unsigned                len = (*src)->bLength;
  48
  49                 if (len > buflen)
  50                         return -EINVAL;
  51                 memcpy(dest, *src, len);
  52                 buflen -= len;
  53                 dest += len;
  54         }
  55         return dest - (u8 *)buf;
  56 }
  57 EXPORT_SYMBOL_GPL(usb_descriptor_fillbuf);
  58
  59 /**
  60  * usb_gadget_config_buf - builts a complete configuration descriptor
  61  * @config: Header for the descriptor, including characteristics such
  62  *      as power requirements and number of interfaces.
  63  * @desc: Null-terminated vector of pointers to the descriptors (interface,
  64  *      endpoint, etc) defining all functions in this device configuration.
  65  * @buf: Buffer for the resulting configuration descriptor.
  66  * @length: Length of buffer.  If this is not big enough to hold the
  67  *      entire configuration descriptor, an error code will be returned.
  68  *
  69  * This copies descriptors into the response buffer, building a descriptor
  70  * for that configuration.  It returns the buffer length or a negative
  71  * status code.  The config.wTotalLength field is set to match the length
  72  * of the result, but other descriptor fields (including power usage and
  73  * interface count) must be set by the caller.
  74  *
  75  * Gadget drivers could use this when constructing a config descriptor
  76  * in response to USB_REQ_GET_DESCRIPTOR.  They will need to patch the
  77  * resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
  78  */
  79 int usb_gadget_config_buf(
  80         const struct usb_config_descriptor      *config,
  81         void                                    *buf,
  82         unsigned                                length,
  83         const struct usb_descriptor_header      **desc
  84 )
  85 {
  86         struct usb_config_descriptor            *cp = buf;
  87         int                                     len;
  88
  89         /* config descriptor first */
  90         if (length < USB_DT_CONFIG_SIZE || !desc)
  91                 return -EINVAL;
  92         *cp = *config;
  93
  94         /* then interface/endpoint/class/vendor/... */
  95         len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8*)buf,
  96                         length - USB_DT_CONFIG_SIZE, desc);
  97         if (len < 0)
  98                 return len;
  99         len += USB_DT_CONFIG_SIZE;
 100         if (len > 0xffff)
 101                 return -EINVAL;
 102
 103         /* patch up the config descriptor */
 104         cp->bLength = USB_DT_CONFIG_SIZE;
 105         cp->bDescriptorType = USB_DT_CONFIG;
 106         cp->wTotalLength = cpu_to_le16(len);
 107         cp->bmAttributes |= USB_CONFIG_ATT_ONE;
 108         return len;
 109 }
 110 EXPORT_SYMBOL_GPL(usb_gadget_config_buf);
 111
 112 /**
 113  * usb_copy_descriptors - copy a vector of USB descriptors
 114  * @src: null-terminated vector to copy
 115  * Context: initialization code, which may sleep
 116  *
 117  * This makes a copy of a vector of USB descriptors.  Its primary use
 118  * is to support usb_function objects which can have multiple copies,
 119  * each needing different descriptors.  Functions may have static
 120  * tables of descriptors, which are used as templates and customized
 121  * with identifiers (for interfaces, strings, endpoints, and more)
 122  * as needed by a given function instance.
 123  */
 124 struct usb_descriptor_header **
 125 usb_copy_descriptors(struct usb_descriptor_header **src)
 126 {
 127         struct usb_descriptor_header **tmp;
 128         unsigned bytes;
 129         unsigned n_desc;
 130         void *mem;
 131         struct usb_descriptor_header **ret;
 132
 133         /* count descriptors and their sizes; then add vector size */
 134         for (bytes = 0, n_desc = 0, tmp = src; *tmp; tmp++, n_desc++)
 135                 bytes += (*tmp)->bLength;
 136         bytes += (n_desc + 1) * sizeof(*tmp);
 137
 138         mem = kmalloc(bytes, GFP_KERNEL);
 139         if (!mem)
 140                 return NULL;
 141
 142         /* fill in pointers starting at "tmp",
 143          * to descriptors copied starting at "mem";
 144          * and return "ret"
 145          */
 146         tmp = mem;
 147         ret = mem;
 148         mem += (n_desc + 1) * sizeof(*tmp);
 149         while (*src) {
 150                 memcpy(mem, *src, (*src)->bLength);
 151                 *tmp = mem;
 152                 tmp++;
 153                 mem += (*src)->bLength;
 154                 src++;
 155         }
 156         *tmp = NULL;
 157
 158         return ret;
 159 }
 160 EXPORT_SYMBOL_GPL(usb_copy_descriptors);
 161
 162 int usb_assign_descriptors(struct usb_function *f,
 163                 struct usb_descriptor_header **fs,
 164                 struct usb_descriptor_header **hs,
 165                 struct usb_descriptor_header **ss)
 166 {
 167         struct usb_gadget *g = f->config->cdev->gadget;
 168
 169         if (fs) {
 170                 f->fs_descriptors = usb_copy_descriptors(fs);
 171                 if (!f->fs_descriptors)
 172                         goto err;
 173         }
 174         if (hs && gadget_is_dualspeed(g)) {
 175                 f->hs_descriptors = usb_copy_descriptors(hs);
 176                 if (!f->hs_descriptors)
 177                         goto err;
 178         }
 179         if (ss && gadget_is_superspeed(g)) {
 180                 f->ss_descriptors = usb_copy_descriptors(ss);
 181                 if (!f->ss_descriptors)
 182                         goto err;
 183         }
 184         return 0;
 185 err:
 186         usb_free_all_descriptors(f);
 187         return -ENOMEM;
 188 }
 189 EXPORT_SYMBOL_GPL(usb_assign_descriptors);
 190
 191 void usb_free_all_descriptors(struct usb_function *f)
 192 {
 193         usb_free_descriptors(f->fs_descriptors);
 194         usb_free_descriptors(f->hs_descriptors);
 195         usb_free_descriptors(f->ss_descriptors);
 196 }
 197 EXPORT_SYMBOL_GPL(usb_free_all_descriptors);