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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 */
20
21#include <linux/errno.h>
22#include <linux/kernel.h>
23#include <linux/list.h>
24#include <linux/string.h>
25#include <linux/device.h>
26
27#include <linux/usb_ch9.h>
28#include <linux/usb_gadget.h>
29
30
31/**
32 * usb_descriptor_fillbuf - fill buffer with descriptors
33 * @buf: Buffer to be filled
34 * @buflen: Size of buf
35 * @src: Array of descriptor pointers, terminated by null pointer.
36 *
37 * Copies descriptors into the buffer, returning the length or a
38 * negative error code if they can't all be copied. Useful when
39 * assembling descriptors for an associated set of interfaces used
40 * as part of configuring a composite device; or in other cases where
41 * sets of descriptors need to be marshaled.
42 */
43int
44usb_descriptor_fillbuf(void *buf, unsigned buflen,
45 const struct usb_descriptor_header **src)
46{
47 u8 *dest = buf;
48
49 if (!src)
50 return -EINVAL;
51
52 /* fill buffer from src[] until null descriptor ptr */
53 for (; 0 != *src; src++) {
54 unsigned len = (*src)->bLength;
55
56 if (len > buflen)
57 return -EINVAL;
58 memcpy(dest, *src, len);
59 buflen -= len;
60 dest += len;
61 }
62 return dest - (u8 *)buf;
63}
64
65
66/**
67 * usb_gadget_config_buf - builts a complete configuration descriptor
68 * @config: Header for the descriptor, including characteristics such
69 * as power requirements and number of interfaces.
70 * @desc: Null-terminated vector of pointers to the descriptors (interface,
71 * endpoint, etc) defining all functions in this device configuration.
72 * @buf: Buffer for the resulting configuration descriptor.
73 * @length: Length of buffer. If this is not big enough to hold the
74 * entire configuration descriptor, an error code will be returned.
75 *
76 * This copies descriptors into the response buffer, building a descriptor
77 * for that configuration. It returns the buffer length or a negative
78 * status code. The config.wTotalLength field is set to match the length
79 * of the result, but other descriptor fields (including power usage and
80 * interface count) must be set by the caller.
81 *
82 * Gadget drivers could use this when constructing a config descriptor
83 * in response to USB_REQ_GET_DESCRIPTOR. They will need to patch the
84 * resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
85 */
86int usb_gadget_config_buf(
87 const struct usb_config_descriptor *config,
88 void *buf,
89 unsigned length,
90 const struct usb_descriptor_header **desc
91)
92{
93 struct usb_config_descriptor *cp = buf;
94 int len;
95
96 /* config descriptor first */
97 if (length < USB_DT_CONFIG_SIZE || !desc)
98 return -EINVAL;
99 *cp = *config;
100
101 /* then interface/endpoint/class/vendor/... */
102 len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8*)buf,
103 length - USB_DT_CONFIG_SIZE, desc);
104 if (len < 0)
105 return len;
106 len += USB_DT_CONFIG_SIZE;
107 if (len > 0xffff)
108 return -EINVAL;
109
110 /* patch up the config descriptor */
111 cp->bLength = USB_DT_CONFIG_SIZE;
112 cp->bDescriptorType = USB_DT_CONFIG;
113 cp->wTotalLength = cpu_to_le16(len);
114 cp->bmAttributes |= USB_CONFIG_ATT_ONE;
115 return len;
116}
117