1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * epautoconf.c -- endpoint autoconfiguration for usb gadget drivers
4 *
5 * Copyright (C) 2004 David Brownell
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/types.h>
11 #include <linux/device.h>
12
13 #include <linux/ctype.h>
14 #include <linux/string.h>
15
16 #include <linux/usb/ch9.h>
17 #include <linux/usb/gadget.h>
18
19 /**
20 * usb_ep_autoconfig_ss() - choose an endpoint matching the ep
21 * descriptor and ep companion descriptor
22 * @gadget: The device to which the endpoint must belong.
23 * @desc: Endpoint descriptor, with endpoint direction and transfer mode
24 * initialized. For periodic transfers, the maximum packet
25 * size must also be initialized. This is modified on
26 * success.
27 * @ep_comp: Endpoint companion descriptor, with the required
28 * number of streams. Will be modified when the chosen EP
29 * supports a different number of streams.
30 *
31 * This routine replaces the usb_ep_autoconfig when needed
32 * superspeed enhancments. If such enhancemnets are required,
33 * the FD should call usb_ep_autoconfig_ss directly and provide
34 * the additional ep_comp parameter.
35 *
36 * By choosing an endpoint to use with the specified descriptor,
37 * this routine simplifies writing gadget drivers that work with
38 * multiple USB device controllers. The endpoint would be
39 * passed later to usb_ep_enable(), along with some descriptor.
40 *
41 * That second descriptor won't always be the same as the first one.
42 * For example, isochronous endpoints can be autoconfigured for high
43 * bandwidth, and then used in several lower bandwidth altsettings.
44 * Also, high and full speed descriptors will be different.
45 *
46 * Be sure to examine and test the results of autoconfiguration
47 * on your hardware. This code may not make the best choices
48 * about how to use the USB controller, and it can't know all
49 * the restrictions that may apply. Some combinations of driver
50 * and hardware won't be able to autoconfigure.
51 *
52 * On success, this returns an claimed usb_ep, and modifies the endpoint
53 * descriptor bEndpointAddress. For bulk endpoints, the wMaxPacket value
54 * is initialized as if the endpoint were used at full speed and
55 * the bmAttribute field in the ep companion descriptor is
56 * updated with the assigned number of streams if it is
57 * different from the original value. To prevent the endpoint
58 * from being returned by a later autoconfig call, claims it by
59 * assigning ep->claimed to true.
60 *
61 * On failure, this returns a null endpoint descriptor.
62 */
63 struct usb_ep *usb_ep_autoconfig_ss(
64 struct usb_gadget *gadget,
65 struct usb_endpoint_descriptor *desc,
66 struct usb_ss_ep_comp_descriptor *ep_comp
67 )
68 {
69 struct usb_ep *ep;
70
71 if (gadget->ops->match_ep) {
72 ep = gadget->ops->match_ep(gadget, desc, ep_comp);
73 if (ep)
74 goto found_ep;
75 }
76
77 /* Second, look at endpoints until an unclaimed one looks usable */
78 list_for_each_entry (ep, &gadget->ep_list, ep_list) {
79 if (usb_gadget_ep_match_desc(gadget, ep, desc, ep_comp))
80 goto found_ep;
81 }
82
83 /* Fail */
84 return NULL;
85 found_ep:
86
87 /*
88 * If the protocol driver hasn't yet decided on wMaxPacketSize
89 * and wants to know the maximum possible, provide the info.
90 */
91 if (desc->wMaxPacketSize == 0)
92 desc->wMaxPacketSize = cpu_to_le16(ep->maxpacket_limit);
93
94 /* report address */
95 desc->bEndpointAddress &= USB_DIR_IN;
96 if (isdigit(ep->name[2])) {
97 u8 num = simple_strtoul(&ep->name[2], NULL, 10);
98 desc->bEndpointAddress |= num;
99 } else if (desc->bEndpointAddress & USB_DIR_IN) {
100 if (++gadget->in_epnum > 15)
101 return NULL;
102 desc->bEndpointAddress = USB_DIR_IN | gadget->in_epnum;
103 } else {
104 if (++gadget->out_epnum > 15)
105 return NULL;
106 desc->bEndpointAddress |= gadget->out_epnum;
107 }
108
109 ep->address = desc->bEndpointAddress;
110 ep->desc = NULL;
111 ep->comp_desc = NULL;
112 ep->claimed = true;
113 return ep;
114 }
115 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_ss);
116
117 /**
118 * usb_ep_autoconfig() - choose an endpoint matching the
119 * descriptor
120 * @gadget: The device to which the endpoint must belong.
121 * @desc: Endpoint descriptor, with endpoint direction and transfer mode
122 * initialized. For periodic transfers, the maximum packet
123 * size must also be initialized. This is modified on success.
124 *
125 * By choosing an endpoint to use with the specified descriptor, this
126 * routine simplifies writing gadget drivers that work with multiple
127 * USB device controllers. The endpoint would be passed later to
128 * usb_ep_enable(), along with some descriptor.
129 *
130 * That second descriptor won't always be the same as the first one.
131 * For example, isochronous endpoints can be autoconfigured for high
132 * bandwidth, and then used in several lower bandwidth altsettings.
133 * Also, high and full speed descriptors will be different.
134 *
135 * Be sure to examine and test the results of autoconfiguration on your
136 * hardware. This code may not make the best choices about how to use the
137 * USB controller, and it can't know all the restrictions that may apply.
138 * Some combinations of driver and hardware won't be able to autoconfigure.
139 *
140 * On success, this returns an claimed usb_ep, and modifies the endpoint
141 * descriptor bEndpointAddress. For bulk endpoints, the wMaxPacket value
142 * is initialized as if the endpoint were used at full speed. Because of
143 * that the users must consider adjusting the autoconfigured descriptor.
144 * To prevent the endpoint from being returned by a later autoconfig call,
145 * claims it by assigning ep->claimed to true.
146 *
147 * On failure, this returns a null endpoint descriptor.
148 */
149 struct usb_ep *usb_ep_autoconfig(
150 struct usb_gadget *gadget,
151 struct usb_endpoint_descriptor *desc
152 )
153 {
154 struct usb_ep *ep;
155 u8 type;
156
157 ep = usb_ep_autoconfig_ss(gadget, desc, NULL);
158 if (!ep)
159 return NULL;
160
161 type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
162
163 /* report (variable) full speed bulk maxpacket */
164 if (type == USB_ENDPOINT_XFER_BULK) {
165 int size = ep->maxpacket_limit;
166
167 /* min() doesn't work on bitfields with gcc-3.5 */
168 if (size > 64)
169 size = 64;
170 desc->wMaxPacketSize = cpu_to_le16(size);
171 }
172
173 return ep;
174 }
175 EXPORT_SYMBOL_GPL(usb_ep_autoconfig);
176
177 /**
178 * usb_ep_autoconfig_release - releases endpoint and set it to initial state
179 * @ep: endpoint which should be released
180 *
181 * This function can be used during function bind for endpoints obtained
182 * from usb_ep_autoconfig(). It unclaims endpoint claimed by
183 * usb_ep_autoconfig() to make it available for other functions. Endpoint
184 * which was released is no longer invalid and shouldn't be used in
185 * context of function which released it.
186 */
187 void usb_ep_autoconfig_release(struct usb_ep *ep)
188 {
189 ep->claimed = false;
190 ep->driver_data = NULL;
191 }
192 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_release);
193
194 /**
195 * usb_ep_autoconfig_reset - reset endpoint autoconfig state
196 * @gadget: device for which autoconfig state will be reset
197 *
198 * Use this for devices where one configuration may need to assign
199 * endpoint resources very differently from the next one. It clears
200 * state such as ep->claimed and the record of assigned endpoints
201 * used by usb_ep_autoconfig().
202 */
203 void usb_ep_autoconfig_reset (struct usb_gadget *gadget)
204 {
205 struct usb_ep *ep;
206
207 list_for_each_entry (ep, &gadget->ep_list, ep_list) {
208 ep->claimed = false;
209 ep->driver_data = NULL;
210 }
211 gadget->in_epnum = 0;
212 gadget->out_epnum = 0;
213 }
214 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_reset);