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 */
usb_ep_autoconfig_ss(struct usb_gadget * gadget,struct usb_endpoint_descriptor * desc,struct usb_ss_ep_comp_descriptor * ep_comp)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 u8 type;
71
72 type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
73
74 if (gadget->ops->match_ep) {
75 ep = gadget->ops->match_ep(gadget, desc, ep_comp);
76 if (ep)
77 goto found_ep;
78 }
79
80 /* Second, look at endpoints until an unclaimed one looks usable */
81 list_for_each_entry (ep, &gadget->ep_list, ep_list) {
82 if (usb_gadget_ep_match_desc(gadget, ep, desc, ep_comp))
83 goto found_ep;
84 }
85
86 /* Fail */
87 return NULL;
88 found_ep:
89
90 /*
91 * If the protocol driver hasn't yet decided on wMaxPacketSize
92 * and wants to know the maximum possible, provide the info.
93 */
94 if (desc->wMaxPacketSize == 0)
95 desc->wMaxPacketSize = cpu_to_le16(ep->maxpacket_limit);
96
97 /* report address */
98 desc->bEndpointAddress &= USB_DIR_IN;
99 if (isdigit(ep->name[2])) {
100 u8 num = simple_strtoul(&ep->name[2], NULL, 10);
101 desc->bEndpointAddress |= num;
102 } else if (desc->bEndpointAddress & USB_DIR_IN) {
103 if (++gadget->in_epnum > 15)
104 return NULL;
105 desc->bEndpointAddress = USB_DIR_IN | gadget->in_epnum;
106 } else {
107 if (++gadget->out_epnum > 15)
108 return NULL;
109 desc->bEndpointAddress |= gadget->out_epnum;
110 }
111
112 /* report (variable) full speed bulk maxpacket */
113 if ((type == USB_ENDPOINT_XFER_BULK) && !ep_comp) {
114 int size = ep->maxpacket_limit;
115
116 /* min() doesn't work on bitfields with gcc-3.5 */
117 if (size > 64)
118 size = 64;
119 desc->wMaxPacketSize = cpu_to_le16(size);
120 }
121
122 ep->address = desc->bEndpointAddress;
123 ep->desc = NULL;
124 ep->comp_desc = NULL;
125 ep->claimed = true;
126 return ep;
127 }
128 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_ss);
129
130 /**
131 * usb_ep_autoconfig() - choose an endpoint matching the
132 * descriptor
133 * @gadget: The device to which the endpoint must belong.
134 * @desc: Endpoint descriptor, with endpoint direction and transfer mode
135 * initialized. For periodic transfers, the maximum packet
136 * size must also be initialized. This is modified on success.
137 *
138 * By choosing an endpoint to use with the specified descriptor, this
139 * routine simplifies writing gadget drivers that work with multiple
140 * USB device controllers. The endpoint would be passed later to
141 * usb_ep_enable(), along with some descriptor.
142 *
143 * That second descriptor won't always be the same as the first one.
144 * For example, isochronous endpoints can be autoconfigured for high
145 * bandwidth, and then used in several lower bandwidth altsettings.
146 * Also, high and full speed descriptors will be different.
147 *
148 * Be sure to examine and test the results of autoconfiguration on your
149 * hardware. This code may not make the best choices about how to use the
150 * USB controller, and it can't know all the restrictions that may apply.
151 * Some combinations of driver and hardware won't be able to autoconfigure.
152 *
153 * On success, this returns an claimed usb_ep, and modifies the endpoint
154 * descriptor bEndpointAddress. For bulk endpoints, the wMaxPacket value
155 * is initialized as if the endpoint were used at full speed. To prevent
156 * the endpoint from being returned by a later autoconfig call, claims it
157 * by assigning ep->claimed to true.
158 *
159 * On failure, this returns a null endpoint descriptor.
160 */
usb_ep_autoconfig(struct usb_gadget * gadget,struct usb_endpoint_descriptor * desc)161 struct usb_ep *usb_ep_autoconfig(
162 struct usb_gadget *gadget,
163 struct usb_endpoint_descriptor *desc
164 )
165 {
166 return usb_ep_autoconfig_ss(gadget, desc, NULL);
167 }
168 EXPORT_SYMBOL_GPL(usb_ep_autoconfig);
169
170 /**
171 * usb_ep_autoconfig_release - releases endpoint and set it to initial state
172 * @ep: endpoint which should be released
173 *
174 * This function can be used during function bind for endpoints obtained
175 * from usb_ep_autoconfig(). It unclaims endpoint claimed by
176 * usb_ep_autoconfig() to make it available for other functions. Endpoint
177 * which was released is no longer invalid and shouldn't be used in
178 * context of function which released it.
179 */
usb_ep_autoconfig_release(struct usb_ep * ep)180 void usb_ep_autoconfig_release(struct usb_ep *ep)
181 {
182 ep->claimed = false;
183 ep->driver_data = NULL;
184 }
185 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_release);
186
187 /**
188 * usb_ep_autoconfig_reset - reset endpoint autoconfig state
189 * @gadget: device for which autoconfig state will be reset
190 *
191 * Use this for devices where one configuration may need to assign
192 * endpoint resources very differently from the next one. It clears
193 * state such as ep->claimed and the record of assigned endpoints
194 * used by usb_ep_autoconfig().
195 */
usb_ep_autoconfig_reset(struct usb_gadget * gadget)196 void usb_ep_autoconfig_reset (struct usb_gadget *gadget)
197 {
198 struct usb_ep *ep;
199
200 list_for_each_entry (ep, &gadget->ep_list, ep_list) {
201 ep->claimed = false;
202 ep->driver_data = NULL;
203 }
204 gadget->in_epnum = 0;
205 gadget->out_epnum = 0;
206 }
207 EXPORT_SYMBOL_GPL(usb_ep_autoconfig_reset);
208
