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 */
33int
34usb_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}
54EXPORT_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 */
76int 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}
107EXPORT_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 */
121struct usb_descriptor_header **
122usb_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}
157EXPORT_SYMBOL_GPL(usb_copy_descriptors);
158
159int 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	/* super-speed-plus descriptor falls back to super-speed one,
166	 * if such a descriptor was provided, thus avoiding a NULL
167	 * pointer dereference if a 5gbps capable gadget is used with
168	 * a 10gbps capable config (device port + cable + host port)
169	 */
170	if (!ssp)
171		ssp = ss;
172
173	if (fs) {
174		f->fs_descriptors = usb_copy_descriptors(fs);
175		if (!f->fs_descriptors)
176			goto err;
177	}
178	if (hs) {
179		f->hs_descriptors = usb_copy_descriptors(hs);
180		if (!f->hs_descriptors)
181			goto err;
182	}
183	if (ss) {
184		f->ss_descriptors = usb_copy_descriptors(ss);
185		if (!f->ss_descriptors)
186			goto err;
187	}
188	if (ssp) {
189		f->ssp_descriptors = usb_copy_descriptors(ssp);
190		if (!f->ssp_descriptors)
191			goto err;
192	}
193	return 0;
194err:
195	usb_free_all_descriptors(f);
196	return -ENOMEM;
197}
198EXPORT_SYMBOL_GPL(usb_assign_descriptors);
199
200void usb_free_all_descriptors(struct usb_function *f)
201{
202	usb_free_descriptors(f->fs_descriptors);
203	f->fs_descriptors = NULL;
204	usb_free_descriptors(f->hs_descriptors);
205	f->hs_descriptors = NULL;
206	usb_free_descriptors(f->ss_descriptors);
207	f->ss_descriptors = NULL;
208	usb_free_descriptors(f->ssp_descriptors);
209	f->ssp_descriptors = NULL;
210}
211EXPORT_SYMBOL_GPL(usb_free_all_descriptors);
212
213struct usb_descriptor_header *usb_otg_descriptor_alloc(
214				struct usb_gadget *gadget)
215{
216	struct usb_descriptor_header *otg_desc;
217	unsigned length = 0;
218
219	if (gadget->otg_caps && (gadget->otg_caps->otg_rev >= 0x0200))
220		length = sizeof(struct usb_otg20_descriptor);
221	else
222		length = sizeof(struct usb_otg_descriptor);
223
224	otg_desc = kzalloc(length, GFP_KERNEL);
225	return otg_desc;
226}
227EXPORT_SYMBOL_GPL(usb_otg_descriptor_alloc);
228
229int usb_otg_descriptor_init(struct usb_gadget *gadget,
230		struct usb_descriptor_header *otg_desc)
231{
232	struct usb_otg_descriptor *otg1x_desc;
233	struct usb_otg20_descriptor *otg20_desc;
234	struct usb_otg_caps *otg_caps = gadget->otg_caps;
235	u8 otg_attributes = 0;
236
237	if (!otg_desc)
238		return -EINVAL;
239
240	if (otg_caps && otg_caps->otg_rev) {
241		if (otg_caps->hnp_support)
242			otg_attributes |= USB_OTG_HNP;
243		if (otg_caps->srp_support)
244			otg_attributes |= USB_OTG_SRP;
245		if (otg_caps->adp_support && (otg_caps->otg_rev >= 0x0200))
246			otg_attributes |= USB_OTG_ADP;
247	} else {
248		otg_attributes = USB_OTG_SRP | USB_OTG_HNP;
249	}
250
251	if (otg_caps && (otg_caps->otg_rev >= 0x0200)) {
252		otg20_desc = (struct usb_otg20_descriptor *)otg_desc;
253		otg20_desc->bLength = sizeof(struct usb_otg20_descriptor);
254		otg20_desc->bDescriptorType = USB_DT_OTG;
255		otg20_desc->bmAttributes = otg_attributes;
256		otg20_desc->bcdOTG = cpu_to_le16(otg_caps->otg_rev);
257	} else {
258		otg1x_desc = (struct usb_otg_descriptor *)otg_desc;
259		otg1x_desc->bLength = sizeof(struct usb_otg_descriptor);
260		otg1x_desc->bDescriptorType = USB_DT_OTG;
261		otg1x_desc->bmAttributes = otg_attributes;
262	}
263
264	return 0;
265}
266EXPORT_SYMBOL_GPL(usb_otg_descriptor_init);
267