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 */
36 int
usb_descriptor_fillbuf(void * buf,unsigned buflen,const struct usb_descriptor_header ** src)37 usb_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 }
57 EXPORT_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 */
usb_gadget_config_buf(const struct usb_config_descriptor * config,void * buf,unsigned length,const struct usb_descriptor_header ** desc)79 int 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 }
110 EXPORT_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 */
124 struct usb_descriptor_header **
usb_copy_descriptors(struct usb_descriptor_header ** src)125 usb_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 }
160 EXPORT_SYMBOL_GPL(usb_copy_descriptors);
161
usb_assign_descriptors(struct usb_function * f,struct usb_descriptor_header ** fs,struct usb_descriptor_header ** hs,struct usb_descriptor_header ** ss)162 int 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;
185 err:
186 usb_free_all_descriptors(f);
187 return -ENOMEM;
188 }
189 EXPORT_SYMBOL_GPL(usb_assign_descriptors);
190
usb_free_all_descriptors(struct usb_function * f)191 void 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 }
197 EXPORT_SYMBOL_GPL(usb_free_all_descriptors);
198