LXR linux/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 */
  36int
  37usb_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}
  57EXPORT_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 */
  79int 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}
 110EXPORT_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 */
 124struct usb_descriptor_header **
 125usb_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}
 160EXPORT_SYMBOL_GPL(usb_copy_descriptors);
 161
 162int 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;
 185err:
 186        usb_free_all_descriptors(f);
 187        return -ENOMEM;
 188}
 189EXPORT_SYMBOL_GPL(usb_assign_descriptors);
 190
 191void 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}
 197EXPORT_SYMBOL_GPL(usb_free_all_descriptors);
 198