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 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 */ 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 */ 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 */ 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