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