LXR uboot/drivers/usb/gadget/config.c

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * usb/gadget/config.c -- simplify building config descriptors
   4 *
   5 * Copyright (C) 2003 David Brownell
   6 *
   7 * Ported to U-Boot by: Thomas Smits <ts.smits@gmail.com> and
   8 *                      Remy Bohmer <linux@bohmer.net>
   9 */
  10
  11#include <common.h>
  12#include <asm/unaligned.h>
  13#include <linux/errno.h>
  14#include <linux/list.h>
  15#include <linux/string.h>
  16
  17#include <linux/usb/ch9.h>
  18#include <linux/usb/gadget.h>
  19
  20
  21/**
  22 * usb_descriptor_fillbuf - fill buffer with descriptors
  23 * @buf: Buffer to be filled
  24 * @buflen: Size of buf
  25 * @src: Array of descriptor pointers, terminated by null pointer.
  26 *
  27 * Copies descriptors into the buffer, returning the length or a
  28 * negative error code if they can't all be copied.  Useful when
  29 * assembling descriptors for an associated set of interfaces used
  30 * as part of configuring a composite device; or in other cases where
  31 * sets of descriptors need to be marshaled.
  32 */
  33int
  34usb_descriptor_fillbuf(void *buf, unsigned buflen,
  35                const struct usb_descriptor_header **src)
  36{
  37        u8      *dest = buf;
  38
  39        if (!src)
  40                return -EINVAL;
  41
  42        /* fill buffer from src[] until null descriptor ptr */
  43        for (; NULL != *src; src++) {
  44                unsigned                len = (*src)->bLength;
  45
  46                if (len > buflen)
  47                        return -EINVAL;
  48                memcpy(dest, *src, len);
  49                buflen -= len;
  50                dest += len;
  51        }
  52        return dest - (u8 *)buf;
  53}
  54
  55
  56/**
  57 * usb_gadget_config_buf - builts a complete configuration descriptor
  58 * @config: Header for the descriptor, including characteristics such
  59 *      as power requirements and number of interfaces.
  60 * @desc: Null-terminated vector of pointers to the descriptors (interface,
  61 *      endpoint, etc) defining all functions in this device configuration.
  62 * @buf: Buffer for the resulting configuration descriptor.
  63 * @length: Length of buffer.  If this is not big enough to hold the
  64 *      entire configuration descriptor, an error code will be returned.
  65 *
  66 * This copies descriptors into the response buffer, building a descriptor
  67 * for that configuration.  It returns the buffer length or a negative
  68 * status code.  The config.wTotalLength field is set to match the length
  69 * of the result, but other descriptor fields (including power usage and
  70 * interface count) must be set by the caller.
  71 *
  72 * Gadget drivers could use this when constructing a config descriptor
  73 * in response to USB_REQ_GET_DESCRIPTOR.  They will need to patch the
  74 * resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
  75 */
  76int usb_gadget_config_buf(
  77        const struct usb_config_descriptor      *config,
  78        void                                    *buf,
  79        unsigned                                length,
  80        const struct usb_descriptor_header      **desc
  81)
  82{
  83        struct usb_config_descriptor            *cp = buf;
  84        int                                     len;
  85
  86        /* config descriptor first */
  87        if (length < USB_DT_CONFIG_SIZE || !desc)
  88                return -EINVAL;
  89        /* config need not be aligned */
  90        memcpy(cp, config, sizeof(*cp));
  91
  92        /* then interface/endpoint/class/vendor/... */
  93        len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8 *)buf,
  94                        length - USB_DT_CONFIG_SIZE, desc);
  95        if (len < 0)
  96                return len;
  97        len += USB_DT_CONFIG_SIZE;
  98        if (len > 0xffff)
  99                return -EINVAL;
 100
 101        /* patch up the config descriptor */
 102        cp->bLength = USB_DT_CONFIG_SIZE;
 103        cp->bDescriptorType = USB_DT_CONFIG;
 104        put_unaligned_le16(len, &cp->wTotalLength);
 105        cp->bmAttributes |= USB_CONFIG_ATT_ONE;
 106        return len;
 107}
 108