xref: /openbmc/u-boot/drivers/usb/gadget/config.c (revision 63e22517)
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  * Ported to U-Boot by: Thomas Smits <ts.smits@gmail.com> and
8  *                      Remy Bohmer <linux@bohmer.net>
9  */
10 
11 #include <common.h>
12 #include <asm/unaligned.h>
13 #include <linux/errno.h>
14 #include <linux/list.h>
15 #include <linux/string.h>
16 
17 #include <linux/usb/ch9.h>
18 #include <linux/usb/gadget.h>
19 
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
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 
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  */
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 	/* config need not be aligned */
90 	memcpy(cp, config, sizeof(*cp));
91 
92 	/* then interface/endpoint/class/vendor/... */
93 	len = usb_descriptor_fillbuf(USB_DT_CONFIG_SIZE + (u8 *)buf,
94 			length - USB_DT_CONFIG_SIZE, desc);
95 	if (len < 0)
96 		return len;
97 	len += USB_DT_CONFIG_SIZE;
98 	if (len > 0xffff)
99 		return -EINVAL;
100 
101 	/* patch up the config descriptor */
102 	cp->bLength = USB_DT_CONFIG_SIZE;
103 	cp->bDescriptorType = USB_DT_CONFIG;
104 	put_unaligned_le16(len, &cp->wTotalLength);
105 	cp->bmAttributes |= USB_CONFIG_ATT_ONE;
106 	return len;
107 }
108