summaryrefslogtreecommitdiff
path: root/drivers/usb/gadget/epautoconf.c
blob: 71b15c65b90f994fc1fbc4f548e232e09c308f69 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
// SPDX-License-Identifier: GPL-2.0+
/*
 * epautoconf.c -- endpoint autoconfiguration for usb gadget drivers
 *
 * Copyright (C) 2004 David Brownell
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/device.h>

#include <linux/ctype.h>
#include <linux/string.h>

#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>

/**
 * usb_ep_autoconfig_ss() - choose an endpoint matching the ep
 * descriptor and ep companion descriptor
 * @gadget: The device to which the endpoint must belong.
 * @desc: Endpoint descriptor, with endpoint direction and transfer mode
 *    initialized.  For periodic transfers, the maximum packet
 *    size must also be initialized.  This is modified on
 *    success.
 * @ep_comp: Endpoint companion descriptor, with the required
 *    number of streams. Will be modified when the chosen EP
 *    supports a different number of streams.
 *
 * This routine replaces the usb_ep_autoconfig when needed
 * superspeed enhancments. If such enhancemnets are required,
 * the FD should call usb_ep_autoconfig_ss directly and provide
 * the additional ep_comp parameter.
 *
 * By choosing an endpoint to use with the specified descriptor,
 * this routine simplifies writing gadget drivers that work with
 * multiple USB device controllers.  The endpoint would be
 * passed later to usb_ep_enable(), along with some descriptor.
 *
 * That second descriptor won't always be the same as the first one.
 * For example, isochronous endpoints can be autoconfigured for high
 * bandwidth, and then used in several lower bandwidth altsettings.
 * Also, high and full speed descriptors will be different.
 *
 * Be sure to examine and test the results of autoconfiguration
 * on your hardware.  This code may not make the best choices
 * about how to use the USB controller, and it can't know all
 * the restrictions that may apply. Some combinations of driver
 * and hardware won't be able to autoconfigure.
 *
 * On success, this returns an claimed usb_ep, and modifies the endpoint
 * descriptor bEndpointAddress.  For bulk endpoints, the wMaxPacket value
 * is initialized as if the endpoint were used at full speed and
 * the bmAttribute field in the ep companion descriptor is
 * updated with the assigned number of streams if it is
 * different from the original value. To prevent the endpoint
 * from being returned by a later autoconfig call, claims it by
 * assigning ep->claimed to true.
 *
 * On failure, this returns a null endpoint descriptor.
 */
struct usb_ep *usb_ep_autoconfig_ss(
	struct usb_gadget		*gadget,
	struct usb_endpoint_descriptor	*desc,
	struct usb_ss_ep_comp_descriptor *ep_comp
)
{
	struct usb_ep	*ep;
	u8		type;

	type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;

	if (gadget->ops->match_ep) {
		ep = gadget->ops->match_ep(gadget, desc, ep_comp);
		if (ep)
			goto found_ep;
	}

	/* Second, look at endpoints until an unclaimed one looks usable */
	list_for_each_entry (ep, &gadget->ep_list, ep_list) {
		if (usb_gadget_ep_match_desc(gadget, ep, desc, ep_comp))
			goto found_ep;
	}

	/* Fail */
	return NULL;
found_ep:

	/*
	 * If the protocol driver hasn't yet decided on wMaxPacketSize
	 * and wants to know the maximum possible, provide the info.
	 */
	if (desc->wMaxPacketSize == 0)
		desc->wMaxPacketSize = cpu_to_le16(ep->maxpacket_limit);

	/* report address */
	desc->bEndpointAddress &= USB_DIR_IN;
	if (isdigit(ep->name[2])) {
		u8 num = simple_strtoul(&ep->name[2], NULL, 10);
		desc->bEndpointAddress |= num;
	} else if (desc->bEndpointAddress & USB_DIR_IN) {
		if (++gadget->in_epnum > 15)
			return NULL;
		desc->bEndpointAddress = USB_DIR_IN | gadget->in_epnum;
	} else {
		if (++gadget->out_epnum > 15)
			return NULL;
		desc->bEndpointAddress |= gadget->out_epnum;
	}

	/* report (variable) full speed bulk maxpacket */
	if ((type == USB_ENDPOINT_XFER_BULK) && !ep_comp) {
		int size = ep->maxpacket_limit;

		/* min() doesn't work on bitfields with gcc-3.5 */
		if (size > 64)
			size = 64;
		desc->wMaxPacketSize = cpu_to_le16(size);
	}

	ep->address = desc->bEndpointAddress;
	ep->desc = NULL;
	ep->comp_desc = NULL;
	ep->claimed = true;
	return ep;
}
EXPORT_SYMBOL_GPL(usb_ep_autoconfig_ss);

/**
 * usb_ep_autoconfig() - choose an endpoint matching the
 * descriptor
 * @gadget: The device to which the endpoint must belong.
 * @desc: Endpoint descriptor, with endpoint direction and transfer mode
 *	initialized.  For periodic transfers, the maximum packet
 *	size must also be initialized.  This is modified on success.
 *
 * By choosing an endpoint to use with the specified descriptor, this
 * routine simplifies writing gadget drivers that work with multiple
 * USB device controllers.  The endpoint would be passed later to
 * usb_ep_enable(), along with some descriptor.
 *
 * That second descriptor won't always be the same as the first one.
 * For example, isochronous endpoints can be autoconfigured for high
 * bandwidth, and then used in several lower bandwidth altsettings.
 * Also, high and full speed descriptors will be different.
 *
 * Be sure to examine and test the results of autoconfiguration on your
 * hardware.  This code may not make the best choices about how to use the
 * USB controller, and it can't know all the restrictions that may apply.
 * Some combinations of driver and hardware won't be able to autoconfigure.
 *
 * On success, this returns an claimed usb_ep, and modifies the endpoint
 * descriptor bEndpointAddress.  For bulk endpoints, the wMaxPacket value
 * is initialized as if the endpoint were used at full speed.  To prevent
 * the endpoint from being returned by a later autoconfig call, claims it
 * by assigning ep->claimed to true.
 *
 * On failure, this returns a null endpoint descriptor.
 */
struct usb_ep *usb_ep_autoconfig(
	struct usb_gadget		*gadget,
	struct usb_endpoint_descriptor	*desc
)
{
	return usb_ep_autoconfig_ss(gadget, desc, NULL);
}
EXPORT_SYMBOL_GPL(usb_ep_autoconfig);

/**
 * usb_ep_autoconfig_release - releases endpoint and set it to initial state
 * @ep: endpoint which should be released
 *
 * This function can be used during function bind for endpoints obtained
 * from usb_ep_autoconfig(). It unclaims endpoint claimed by
 * usb_ep_autoconfig() to make it available for other functions. Endpoint
 * which was released is no longer invalid and shouldn't be used in
 * context of function which released it.
 */
void usb_ep_autoconfig_release(struct usb_ep *ep)
{
	ep->claimed = false;
	ep->driver_data = NULL;
}
EXPORT_SYMBOL_GPL(usb_ep_autoconfig_release);

/**
 * usb_ep_autoconfig_reset - reset endpoint autoconfig state
 * @gadget: device for which autoconfig state will be reset
 *
 * Use this for devices where one configuration may need to assign
 * endpoint resources very differently from the next one.  It clears
 * state such as ep->claimed and the record of assigned endpoints
 * used by usb_ep_autoconfig().
 */
void usb_ep_autoconfig_reset (struct usb_gadget *gadget)
{
	struct usb_ep	*ep;

	list_for_each_entry (ep, &gadget->ep_list, ep_list) {
		ep->claimed = false;
		ep->driver_data = NULL;
	}
	gadget->in_epnum = 0;
	gadget->out_epnum = 0;
}
EXPORT_SYMBOL_GPL(usb_ep_autoconfig_reset);