1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * usb/gadget/config.c -- simplify building config descriptors
4  *
5  * Copyright (C) 2003 David Brownell
6  */
7 
8 #include <linux/errno.h>
9 #include <linux/slab.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/list.h>
13 #include <linux/string.h>
14 #include <linux/device.h>
15 
16 #include <linux/usb/ch9.h>
17 #include <linux/usb/gadget.h>
18 #include <linux/usb/composite.h>
19 #include <linux/usb/otg.h>
20 
21 /**
22  * usb_descriptor_fillbuf - fill buffer with descriptors
23  * @buf: Buffer to be filled
24  * @buflen: Size of buf
25  * @src: Array of descriptor pointers, terminated by null pointer.
26  *
27  * Copies descriptors into the buffer, returning the length or a
28  * negative error code if they can't all be copied.  Useful when
29  * assembling descriptors for an associated set of interfaces used
30  * as part of configuring a composite device; or in other cases where
31  * sets of descriptors need to be marshaled.
32  */
33 int
usb_descriptor_fillbuf(void * buf,unsigned buflen,const struct usb_descriptor_header ** src)34 usb_descriptor_fillbuf(void *buf, unsigned buflen,
35 		const struct usb_descriptor_header **src)
36 {
37 	u8	*dest = buf;
38 
39 	if (!src)
40 		return -EINVAL;
41 
42 	/* fill buffer from src[] until null descriptor ptr */
43 	for (; NULL != *src; src++) {
44 		unsigned		len = (*src)->bLength;
45 
46 		if (len > buflen)
47 			return -EINVAL;
48 		memcpy(dest, *src, len);
49 		buflen -= len;
50 		dest += len;
51 	}
52 	return dest - (u8 *)buf;
53 }
54 EXPORT_SYMBOL_GPL(usb_descriptor_fillbuf);
55 
56 /**
57  * usb_gadget_config_buf - builts a complete configuration descriptor
58  * @config: Header for the descriptor, including characteristics such
59  *	as power requirements and number of interfaces.
60  * @desc: Null-terminated vector of pointers to the descriptors (interface,
61  *	endpoint, etc) defining all functions in this device configuration.
62  * @buf: Buffer for the resulting configuration descriptor.
63  * @length: Length of buffer.  If this is not big enough to hold the
64  *	entire configuration descriptor, an error code will be returned.
65  *
66  * This copies descriptors into the response buffer, building a descriptor
67  * for that configuration.  It returns the buffer length or a negative
68  * status code.  The config.wTotalLength field is set to match the length
69  * of the result, but other descriptor fields (including power usage and
70  * interface count) must be set by the caller.
71  *
72  * Gadget drivers could use this when constructing a config descriptor
73  * in response to USB_REQ_GET_DESCRIPTOR.  They will need to patch the
74  * resulting bDescriptorType value if USB_DT_OTHER_SPEED_CONFIG is needed.
75  */
usb_gadget_config_buf(const struct usb_config_descriptor * config,void * buf,unsigned length,const struct usb_descriptor_header ** desc)76 int usb_gadget_config_buf(
77 	const struct usb_config_descriptor	*config,
78 	void					*buf,
79 	unsigned				length,
80 	const struct usb_descriptor_header	**desc
81 )
82 {
83 	struct usb_config_descriptor		*cp = buf;
84 	int					len;
85 
86 	/* config descriptor first */
87 	if (length < USB_DT_CONFIG_SIZE || !desc)
88 		return -EINVAL;
89 	*cp = *config;
90 
91 	/* then interface/endpoint/class/vendor/... */
92 	len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8 *)buf,
93 			length - USB_DT_CONFIG_SIZE, desc);
94 	if (len < 0)
95 		return len;
96 	len += USB_DT_CONFIG_SIZE;
97 	if (len > 0xffff)
98 		return -EINVAL;
99 
100 	/* patch up the config descriptor */
101 	cp->bLength = USB_DT_CONFIG_SIZE;
102 	cp->bDescriptorType = USB_DT_CONFIG;
103 	cp->wTotalLength = cpu_to_le16(len);
104 	cp->bmAttributes |= USB_CONFIG_ATT_ONE;
105 	return len;
106 }
107 EXPORT_SYMBOL_GPL(usb_gadget_config_buf);
108 
109 /**
110  * usb_copy_descriptors - copy a vector of USB descriptors
111  * @src: null-terminated vector to copy
112  * Context: initialization code, which may sleep
113  *
114  * This makes a copy of a vector of USB descriptors.  Its primary use
115  * is to support usb_function objects which can have multiple copies,
116  * each needing different descriptors.  Functions may have static
117  * tables of descriptors, which are used as templates and customized
118  * with identifiers (for interfaces, strings, endpoints, and more)
119  * as needed by a given function instance.
120  */
121 struct usb_descriptor_header **
usb_copy_descriptors(struct usb_descriptor_header ** src)122 usb_copy_descriptors(struct usb_descriptor_header **src)
123 {
124 	struct usb_descriptor_header **tmp;
125 	unsigned bytes;
126 	unsigned n_desc;
127 	void *mem;
128 	struct usb_descriptor_header **ret;
129 
130 	/* count descriptors and their sizes; then add vector size */
131 	for (bytes = 0, n_desc = 0, tmp = src; *tmp; tmp++, n_desc++)
132 		bytes += (*tmp)->bLength;
133 	bytes += (n_desc + 1) * sizeof(*tmp);
134 
135 	mem = kmalloc(bytes, GFP_KERNEL);
136 	if (!mem)
137 		return NULL;
138 
139 	/* fill in pointers starting at "tmp",
140 	 * to descriptors copied starting at "mem";
141 	 * and return "ret"
142 	 */
143 	tmp = mem;
144 	ret = mem;
145 	mem += (n_desc + 1) * sizeof(*tmp);
146 	while (*src) {
147 		memcpy(mem, *src, (*src)->bLength);
148 		*tmp = mem;
149 		tmp++;
150 		mem += (*src)->bLength;
151 		src++;
152 	}
153 	*tmp = NULL;
154 
155 	return ret;
156 }
157 EXPORT_SYMBOL_GPL(usb_copy_descriptors);
158 
usb_assign_descriptors(struct usb_function * f,struct usb_descriptor_header ** fs,struct usb_descriptor_header ** hs,struct usb_descriptor_header ** ss,struct usb_descriptor_header ** ssp)159 int usb_assign_descriptors(struct usb_function *f,
160 		struct usb_descriptor_header **fs,
161 		struct usb_descriptor_header **hs,
162 		struct usb_descriptor_header **ss,
163 		struct usb_descriptor_header **ssp)
164 {
165 	struct usb_gadget *g = f->config->cdev->gadget;
166 
167 	/* super-speed-plus descriptor falls back to super-speed one,
168 	 * if such a descriptor was provided, thus avoiding a NULL
169 	 * pointer dereference if a 5gbps capable gadget is used with
170 	 * a 10gbps capable config (device port + cable + host port)
171 	 */
172 	if (!ssp)
173 		ssp = ss;
174 
175 	if (fs) {
176 		f->fs_descriptors = usb_copy_descriptors(fs);
177 		if (!f->fs_descriptors)
178 			goto err;
179 	}
180 	if (hs && gadget_is_dualspeed(g)) {
181 		f->hs_descriptors = usb_copy_descriptors(hs);
182 		if (!f->hs_descriptors)
183 			goto err;
184 	}
185 	if (ss && gadget_is_superspeed(g)) {
186 		f->ss_descriptors = usb_copy_descriptors(ss);
187 		if (!f->ss_descriptors)
188 			goto err;
189 	}
190 	if (ssp && gadget_is_superspeed_plus(g)) {
191 		f->ssp_descriptors = usb_copy_descriptors(ssp);
192 		if (!f->ssp_descriptors)
193 			goto err;
194 	}
195 	return 0;
196 err:
197 	usb_free_all_descriptors(f);
198 	return -ENOMEM;
199 }
200 EXPORT_SYMBOL_GPL(usb_assign_descriptors);
201 
usb_free_all_descriptors(struct usb_function * f)202 void usb_free_all_descriptors(struct usb_function *f)
203 {
204 	usb_free_descriptors(f->fs_descriptors);
205 	f->fs_descriptors = NULL;
206 	usb_free_descriptors(f->hs_descriptors);
207 	f->hs_descriptors = NULL;
208 	usb_free_descriptors(f->ss_descriptors);
209 	f->ss_descriptors = NULL;
210 	usb_free_descriptors(f->ssp_descriptors);
211 	f->ssp_descriptors = NULL;
212 }
213 EXPORT_SYMBOL_GPL(usb_free_all_descriptors);
214 
usb_otg_descriptor_alloc(struct usb_gadget * gadget)215 struct usb_descriptor_header *usb_otg_descriptor_alloc(
216 				struct usb_gadget *gadget)
217 {
218 	struct usb_descriptor_header *otg_desc;
219 	unsigned length = 0;
220 
221 	if (gadget->otg_caps && (gadget->otg_caps->otg_rev >= 0x0200))
222 		length = sizeof(struct usb_otg20_descriptor);
223 	else
224 		length = sizeof(struct usb_otg_descriptor);
225 
226 	otg_desc = kzalloc(length, GFP_KERNEL);
227 	return otg_desc;
228 }
229 EXPORT_SYMBOL_GPL(usb_otg_descriptor_alloc);
230 
usb_otg_descriptor_init(struct usb_gadget * gadget,struct usb_descriptor_header * otg_desc)231 int usb_otg_descriptor_init(struct usb_gadget *gadget,
232 		struct usb_descriptor_header *otg_desc)
233 {
234 	struct usb_otg_descriptor *otg1x_desc;
235 	struct usb_otg20_descriptor *otg20_desc;
236 	struct usb_otg_caps *otg_caps = gadget->otg_caps;
237 	u8 otg_attributes = 0;
238 
239 	if (!otg_desc)
240 		return -EINVAL;
241 
242 	if (otg_caps && otg_caps->otg_rev) {
243 		if (otg_caps->hnp_support)
244 			otg_attributes |= USB_OTG_HNP;
245 		if (otg_caps->srp_support)
246 			otg_attributes |= USB_OTG_SRP;
247 		if (otg_caps->adp_support && (otg_caps->otg_rev >= 0x0200))
248 			otg_attributes |= USB_OTG_ADP;
249 	} else {
250 		otg_attributes = USB_OTG_SRP | USB_OTG_HNP;
251 	}
252 
253 	if (otg_caps && (otg_caps->otg_rev >= 0x0200)) {
254 		otg20_desc = (struct usb_otg20_descriptor *)otg_desc;
255 		otg20_desc->bLength = sizeof(struct usb_otg20_descriptor);
256 		otg20_desc->bDescriptorType = USB_DT_OTG;
257 		otg20_desc->bmAttributes = otg_attributes;
258 		otg20_desc->bcdOTG = cpu_to_le16(otg_caps->otg_rev);
259 	} else {
260 		otg1x_desc = (struct usb_otg_descriptor *)otg_desc;
261 		otg1x_desc->bLength = sizeof(struct usb_otg_descriptor);
262 		otg1x_desc->bDescriptorType = USB_DT_OTG;
263 		otg1x_desc->bmAttributes = otg_attributes;
264 	}
265 
266 	return 0;
267 }
268 EXPORT_SYMBOL_GPL(usb_otg_descriptor_init);
269