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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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 */
11
12#include <linux/errno.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090013#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/kernel.h>
Sebastian Andrzej Siewior0ba16de2012-09-06 20:11:10 +020015#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <linux/list.h>
17#include <linux/string.h>
18#include <linux/device.h>
19
David Brownell5f848132006-12-16 15:34:53 -080020#include <linux/usb/ch9.h>
David Brownell9454a572007-10-04 18:05:17 -070021#include <linux/usb/gadget.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022
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 */
David Brownella9475222007-07-30 12:31:07 -070046 for (; NULL != *src; src++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 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}
Sebastian Andrzej Siewior0ba16de2012-09-06 20:11:10 +020057EXPORT_SYMBOL_GPL(usb_descriptor_fillbuf);
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
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;
David Brownella4c39c42008-06-19 17:52:25 -070092 *cp = *config;
Linus Torvalds1da177e2005-04-16 15:20:36 -070093
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}
Sebastian Andrzej Siewior0ba16de2012-09-06 20:11:10 +0200110EXPORT_SYMBOL_GPL(usb_gadget_config_buf);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111
David Brownella4c39c42008-06-19 17:52:25 -0700112/**
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 */
Michal Nazarewicz28824b12010-05-05 12:53:13 +0200124struct usb_descriptor_header **
David Brownella4c39c42008-06-19 17:52:25 -0700125usb_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}
Sebastian Andrzej Siewior0ba16de2012-09-06 20:11:10 +0200160EXPORT_SYMBOL_GPL(usb_copy_descriptors);