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); 215