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/list.h>
16#include <linux/string.h>
17#include <linux/device.h>
18
19#include <linux/usb/ch9.h>
20#include <linux/usb/gadget.h>
21
22
23/**
24 * usb_descriptor_fillbuf - fill buffer with descriptors
25 * @buf: Buffer to be filled
26 * @buflen: Size of buf
27 * @src: Array of descriptor pointers, terminated by null pointer.
28 *
29 * Copies descriptors into the buffer, returning the length or a
30 * negative error code if they can't all be copied.  Useful when
31 * assembling descriptors for an associated set of interfaces used
32 * as part of configuring a composite device; or in other cases where
33 * sets of descriptors need to be marshaled.
34 */
35int
36usb_descriptor_fillbuf(void *buf, unsigned buflen,
37		const struct usb_descriptor_header **src)
38{
39	u8	*dest = buf;
40
41	if (!src)
42		return -EINVAL;
43
44	/* fill buffer from src[] until null descriptor ptr */
45	for (; NULL != *src; src++) {
46		unsigned		len = (*src)->bLength;
47
48		if (len > buflen)
49			return -EINVAL;
50		memcpy(dest, *src, len);
51		buflen -= len;
52		dest += len;
53	}
54	return dest - (u8 *)buf;
55}
56
57
58/**
59 * usb_gadget_config_buf - builts a complete configuration descriptor
60 * @config: Header for the descriptor, including characteristics such
61 *	as power requirements and number of interfaces.
62 * @desc: Null-terminated vector of pointers to the descriptors (interface,
63 *	endpoint, etc) defining all functions in this device configuration.
64 * @buf: Buffer for the resulting configuration descriptor.
65 * @length: Length of buffer.  If this is not big enough to hold the
66 *	entire configuration descriptor, an error code will be returned.
67 *
68 * This copies descriptors into the response buffer, building a descriptor
69 * for that configuration.  It returns the buffer length or a negative
70 * status code.  The config.wTotalLength field is set to match the length
71 * of the result, but other descriptor fields (including power usage and
72 * interface count) must be set by the caller.
73 *
74 * Gadget drivers could use this when constructing a config descriptor
75 * in response to USB_REQ_GET_DESCRIPTOR.  They will need to patch the
76 * resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
77 */
78int usb_gadget_config_buf(
79	const struct usb_config_descriptor	*config,
80	void					*buf,
81	unsigned				length,
82	const struct usb_descriptor_header	**desc
83)
84{
85	struct usb_config_descriptor		*cp = buf;
86	int					len;
87
88	/* config descriptor first */
89	if (length < USB_DT_CONFIG_SIZE || !desc)
90		return -EINVAL;
91	*cp = *config;
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	cp->wTotalLength = cpu_to_le16(len);
106	cp->bmAttributes |= USB_CONFIG_ATT_ONE;
107	return len;
108}
109
110/**
111 * usb_copy_descriptors - copy a vector of USB descriptors
112 * @src: null-terminated vector to copy
113 * Context: initialization code, which may sleep
114 *
115 * This makes a copy of a vector of USB descriptors.  Its primary use
116 * is to support usb_function objects which can have multiple copies,
117 * each needing different descriptors.  Functions may have static
118 * tables of descriptors, which are used as templates and customized
119 * with identifiers (for interfaces, strings, endpoints, and more)
120 * as needed by a given function instance.
121 */
122struct usb_descriptor_header **
123usb_copy_descriptors(struct usb_descriptor_header **src)
124{
125	struct usb_descriptor_header **tmp;
126	unsigned bytes;
127	unsigned n_desc;
128	void *mem;
129	struct usb_descriptor_header **ret;
130
131	/* count descriptors and their sizes; then add vector size */
132	for (bytes = 0, n_desc = 0, tmp = src; *tmp; tmp++, n_desc++)
133		bytes += (*tmp)->bLength;
134	bytes += (n_desc + 1) * sizeof(*tmp);
135
136	mem = kmalloc(bytes, GFP_KERNEL);
137	if (!mem)
138		return NULL;
139
140	/* fill in pointers starting at "tmp",
141	 * to descriptors copied starting at "mem";
142	 * and return "ret"
143	 */
144	tmp = mem;
145	ret = mem;
146	mem += (n_desc + 1) * sizeof(*tmp);
147	while (*src) {
148		memcpy(mem, *src, (*src)->bLength);
149		*tmp = mem;
150		tmp++;
151		mem += (*src)->bLength;
152		src++;
153	}
154	*tmp = NULL;
155
156	return ret;
157}
158
159