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 */
35 int
usb_descriptor_fillbuf(void * buf,unsigned buflen,const struct usb_descriptor_header ** src)36 usb_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 */
usb_gadget_config_buf(const struct usb_config_descriptor * config,void * buf,unsigned length,const struct usb_descriptor_header ** desc)78 int 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 */
122 struct usb_descriptor_header **
usb_copy_descriptors(struct usb_descriptor_header ** src)123 usb_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