drivers/usb/gadget/config.c

   1 /*
   2  * usb/gadget/config.c -- simplify building config descriptors
   3  *
   4  * Copyright (C) 2003 David Brownell
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  *
   8  * Ported to U-boot by: Thomas Smits <ts.smits@gmail.com> and
   9  *                      Remy Bohmer <linux@bohmer.net>
  10  */
  11
  12 #include <common.h>
  13 #include <asm/unaligned.h>
  14 #include <asm/errno.h>
  15 #include <linux/list.h>
  16 #include <linux/string.h>
  17
  18 #include <linux/usb/ch9.h>
  19 #include <linux/usb/gadget.h>
  20
  21
  22 /**
  23  * usb_descriptor_fillbuf - fill buffer with descriptors
  24  * @buf: Buffer to be filled
  25  * @buflen: Size of buf
  26  * @src: Array of descriptor pointers, terminated by null pointer.
  27  *
  28  * Copies descriptors into the buffer, returning the length or a
  29  * negative error code if they can't all be copied.  Useful when
  30  * assembling descriptors for an associated set of interfaces used
  31  * as part of configuring a composite device; or in other cases where
  32  * sets of descriptors need to be marshaled.
  33  */
  34 int
  35 usb_descriptor_fillbuf(void *buf, unsigned buflen,
  36                 const struct usb_descriptor_header **src)
  37 {
  38         u8      *dest = buf;
  39
  40         if (!src)
  41                 return -EINVAL;
  42
  43         /* fill buffer from src[] until null descriptor ptr */
  44         for (; NULL != *src; src++) {
  45                 unsigned                len = (*src)->bLength;
  46
  47                 if (len > buflen)
  48                         return -EINVAL;
  49                 memcpy(dest, *src, len);
  50                 buflen -= len;
  51                 dest += len;
  52         }
  53         return dest - (u8 *)buf;
  54 }
  55
  56
  57 /**
  58  * usb_gadget_config_buf - builts a complete configuration descriptor
  59  * @config: Header for the descriptor, including characteristics such
  60  *      as power requirements and number of interfaces.
  61  * @desc: Null-terminated vector of pointers to the descriptors (interface,
  62  *      endpoint, etc) defining all functions in this device configuration.
  63  * @buf: Buffer for the resulting configuration descriptor.
  64  * @length: Length of buffer.  If this is not big enough to hold the
  65  *      entire configuration descriptor, an error code will be returned.
  66  *
  67  * This copies descriptors into the response buffer, building a descriptor
  68  * for that configuration.  It returns the buffer length or a negative
  69  * status code.  The config.wTotalLength field is set to match the length
  70  * of the result, but other descriptor fields (including power usage and
  71  * interface count) must be set by the caller.
  72  *
  73  * Gadget drivers could use this when constructing a config descriptor
  74  * in response to USB_REQ_GET_DESCRIPTOR.  They will need to patch the
  75  * resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
  76  */
  77 int usb_gadget_config_buf(
  78         const struct usb_config_descriptor      *config,
  79         void                                    *buf,
  80         unsigned                                length,
  81         const struct usb_descriptor_header      **desc
  82 )
  83 {
  84         struct usb_config_descriptor            *cp = buf;
  85         int                                     len;
  86
  87         /* config descriptor first */
  88         if (length < USB_DT_CONFIG_SIZE || !desc)
  89                 return -EINVAL;
  90         /* config need not be aligned */
  91         memcpy(cp, config, sizeof(*cp));
  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         put_unaligned_le16(len, &cp->wTotalLength);
 106         cp->bmAttributes |= USB_CONFIG_ATT_ONE;
 107         return len;
 108 }