drivers/usb/gadget/function/f_eem.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * f_eem.c -- USB CDC Ethernet (EEM) link function driver
   4  *
   5  * Copyright (C) 2003-2005,2008 David Brownell
   6  * Copyright (C) 2008 Nokia Corporation
   7  * Copyright (C) 2009 EF Johnson Technologies
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/device.h>
  13 #include <linux/etherdevice.h>
  14 #include <linux/crc32.h>
  15 #include <linux/slab.h>
  16
  17 #include "u_ether.h"
  18 #include "u_ether_configfs.h"
  19 #include "u_eem.h"
  20
  21 #define EEM_HLEN 2
  22
  23 /*
  24  * This function is a "CDC Ethernet Emulation Model" (CDC EEM)
  25  * Ethernet link.
  26  */
  27
  28 struct f_eem {
  29         struct gether                   port;
  30         u8                              ctrl_id;
  31 };
  32
  33 static inline struct f_eem *func_to_eem(struct usb_function *f)
  34 {
  35         return container_of(f, struct f_eem, port.func);
  36 }
  37
  38 /*-------------------------------------------------------------------------*/
  39
  40 /* interface descriptor: */
  41
  42 static struct usb_interface_descriptor eem_intf = {
  43         .bLength =              sizeof eem_intf,
  44         .bDescriptorType =      USB_DT_INTERFACE,
  45
  46         /* .bInterfaceNumber = DYNAMIC */
  47         .bNumEndpoints =        2,
  48         .bInterfaceClass =      USB_CLASS_COMM,
  49         .bInterfaceSubClass =   USB_CDC_SUBCLASS_EEM,
  50         .bInterfaceProtocol =   USB_CDC_PROTO_EEM,
  51         /* .iInterface = DYNAMIC */
  52 };
  53
  54 /* full speed support: */
  55
  56 static struct usb_endpoint_descriptor eem_fs_in_desc = {
  57         .bLength =              USB_DT_ENDPOINT_SIZE,
  58         .bDescriptorType =      USB_DT_ENDPOINT,
  59
  60         .bEndpointAddress =     USB_DIR_IN,
  61         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  62 };
  63
  64 static struct usb_endpoint_descriptor eem_fs_out_desc = {
  65         .bLength =              USB_DT_ENDPOINT_SIZE,
  66         .bDescriptorType =      USB_DT_ENDPOINT,
  67
  68         .bEndpointAddress =     USB_DIR_OUT,
  69         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  70 };
  71
  72 static struct usb_descriptor_header *eem_fs_function[] = {
  73         /* CDC EEM control descriptors */
  74         (struct usb_descriptor_header *) &eem_intf,
  75         (struct usb_descriptor_header *) &eem_fs_in_desc,
  76         (struct usb_descriptor_header *) &eem_fs_out_desc,
  77         NULL,
  78 };
  79
  80 /* high speed support: */
  81
  82 static struct usb_endpoint_descriptor eem_hs_in_desc = {
  83         .bLength =              USB_DT_ENDPOINT_SIZE,
  84         .bDescriptorType =      USB_DT_ENDPOINT,
  85
  86         .bEndpointAddress =     USB_DIR_IN,
  87         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  88         .wMaxPacketSize =       cpu_to_le16(512),
  89 };
  90
  91 static struct usb_endpoint_descriptor eem_hs_out_desc = {
  92         .bLength =              USB_DT_ENDPOINT_SIZE,
  93         .bDescriptorType =      USB_DT_ENDPOINT,
  94
  95         .bEndpointAddress =     USB_DIR_OUT,
  96         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  97         .wMaxPacketSize =       cpu_to_le16(512),
  98 };
  99
 100 static struct usb_descriptor_header *eem_hs_function[] = {
 101         /* CDC EEM control descriptors */
 102         (struct usb_descriptor_header *) &eem_intf,
 103         (struct usb_descriptor_header *) &eem_hs_in_desc,
 104         (struct usb_descriptor_header *) &eem_hs_out_desc,
 105         NULL,
 106 };
 107
 108 /* super speed support: */
 109
 110 static struct usb_endpoint_descriptor eem_ss_in_desc = {
 111         .bLength =              USB_DT_ENDPOINT_SIZE,
 112         .bDescriptorType =      USB_DT_ENDPOINT,
 113
 114         .bEndpointAddress =     USB_DIR_IN,
 115         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 116         .wMaxPacketSize =       cpu_to_le16(1024),
 117 };
 118
 119 static struct usb_endpoint_descriptor eem_ss_out_desc = {
 120         .bLength =              USB_DT_ENDPOINT_SIZE,
 121         .bDescriptorType =      USB_DT_ENDPOINT,
 122
 123         .bEndpointAddress =     USB_DIR_OUT,
 124         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 125         .wMaxPacketSize =       cpu_to_le16(1024),
 126 };
 127
 128 static struct usb_ss_ep_comp_descriptor eem_ss_bulk_comp_desc = {
 129         .bLength =              sizeof eem_ss_bulk_comp_desc,
 130         .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
 131
 132         /* the following 2 values can be tweaked if necessary */
 133         /* .bMaxBurst =         0, */
 134         /* .bmAttributes =      0, */
 135 };
 136
 137 static struct usb_descriptor_header *eem_ss_function[] = {
 138         /* CDC EEM control descriptors */
 139         (struct usb_descriptor_header *) &eem_intf,
 140         (struct usb_descriptor_header *) &eem_ss_in_desc,
 141         (struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
 142         (struct usb_descriptor_header *) &eem_ss_out_desc,
 143         (struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
 144         NULL,
 145 };
 146
 147 /* string descriptors: */
 148
 149 static struct usb_string eem_string_defs[] = {
 150         [0].s = "CDC Ethernet Emulation Model (EEM)",
 151         {  } /* end of list */
 152 };
 153
 154 static struct usb_gadget_strings eem_string_table = {
 155         .language =             0x0409, /* en-us */
 156         .strings =              eem_string_defs,
 157 };
 158
 159 static struct usb_gadget_strings *eem_strings[] = {
 160         &eem_string_table,
 161         NULL,
 162 };
 163
 164 /*-------------------------------------------------------------------------*/
 165
 166 static int eem_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
 167 {
 168         struct usb_composite_dev *cdev = f->config->cdev;
 169         u16                     w_index = le16_to_cpu(ctrl->wIndex);
 170         u16                     w_value = le16_to_cpu(ctrl->wValue);
 171         u16                     w_length = le16_to_cpu(ctrl->wLength);
 172
 173         DBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
 174                 ctrl->bRequestType, ctrl->bRequest,
 175                 w_value, w_index, w_length);
 176
 177         /* device either stalls (value < 0) or reports success */
 178         return -EOPNOTSUPP;
 179 }
 180
 181
 182 static int eem_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 183 {
 184         struct f_eem            *eem = func_to_eem(f);
 185         struct usb_composite_dev *cdev = f->config->cdev;
 186         struct net_device       *net;
 187
 188         /* we know alt == 0, so this is an activation or a reset */
 189         if (alt != 0)
 190                 goto fail;
 191
 192         if (intf == eem->ctrl_id) {
 193                 DBG(cdev, "reset eem\n");
 194                 gether_disconnect(&eem->port);
 195
 196                 if (!eem->port.in_ep->desc || !eem->port.out_ep->desc) {
 197                         DBG(cdev, "init eem\n");
 198                         if (config_ep_by_speed(cdev->gadget, f,
 199                                                eem->port.in_ep) ||
 200                             config_ep_by_speed(cdev->gadget, f,
 201                                                eem->port.out_ep)) {
 202                                 eem->port.in_ep->desc = NULL;
 203                                 eem->port.out_ep->desc = NULL;
 204                                 goto fail;
 205                         }
 206                 }
 207
 208                 /* zlps should not occur because zero-length EEM packets
 209                  * will be inserted in those cases where they would occur
 210                  */
 211                 eem->port.is_zlp_ok = 1;
 212                 eem->port.cdc_filter = DEFAULT_FILTER;
 213                 DBG(cdev, "activate eem\n");
 214                 net = gether_connect(&eem->port);
 215                 if (IS_ERR(net))
 216                         return PTR_ERR(net);
 217         } else
 218                 goto fail;
 219
 220         return 0;
 221 fail:
 222         return -EINVAL;
 223 }
 224
 225 static void eem_disable(struct usb_function *f)
 226 {
 227         struct f_eem            *eem = func_to_eem(f);
 228         struct usb_composite_dev *cdev = f->config->cdev;
 229
 230         DBG(cdev, "eem deactivated\n");
 231
 232         if (eem->port.in_ep->enabled)
 233                 gether_disconnect(&eem->port);
 234 }
 235
 236 /*-------------------------------------------------------------------------*/
 237
 238 /* EEM function driver setup/binding */
 239
 240 static int eem_bind(struct usb_configuration *c, struct usb_function *f)
 241 {
 242         struct usb_composite_dev *cdev = c->cdev;
 243         struct f_eem            *eem = func_to_eem(f);
 244         struct usb_string       *us;
 245         int                     status;
 246         struct usb_ep           *ep;
 247
 248         struct f_eem_opts       *eem_opts;
 249
 250         eem_opts = container_of(f->fi, struct f_eem_opts, func_inst);
 251         /*
 252          * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
 253          * configurations are bound in sequence with list_for_each_entry,
 254          * in each configuration its functions are bound in sequence
 255          * with list_for_each_entry, so we assume no race condition
 256          * with regard to eem_opts->bound access
 257          */
 258         if (!eem_opts->bound) {
 259                 mutex_lock(&eem_opts->lock);
 260                 gether_set_gadget(eem_opts->net, cdev->gadget);
 261                 status = gether_register_netdev(eem_opts->net);
 262                 mutex_unlock(&eem_opts->lock);
 263                 if (status)
 264                         return status;
 265                 eem_opts->bound = true;
 266         }
 267
 268         us = usb_gstrings_attach(cdev, eem_strings,
 269                                  ARRAY_SIZE(eem_string_defs));
 270         if (IS_ERR(us))
 271                 return PTR_ERR(us);
 272         eem_intf.iInterface = us[0].id;
 273
 274         /* allocate instance-specific interface IDs */
 275         status = usb_interface_id(c, f);
 276         if (status < 0)
 277                 goto fail;
 278         eem->ctrl_id = status;
 279         eem_intf.bInterfaceNumber = status;
 280
 281         status = -ENODEV;
 282
 283         /* allocate instance-specific endpoints */
 284         ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_in_desc);
 285         if (!ep)
 286                 goto fail;
 287         eem->port.in_ep = ep;
 288
 289         ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_out_desc);
 290         if (!ep)
 291                 goto fail;
 292         eem->port.out_ep = ep;
 293
 294         /* support all relevant hardware speeds... we expect that when
 295          * hardware is dual speed, all bulk-capable endpoints work at
 296          * both speeds
 297          */
 298         eem_hs_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
 299         eem_hs_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
 300
 301         eem_ss_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
 302         eem_ss_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
 303
 304         status = usb_assign_descriptors(f, eem_fs_function, eem_hs_function,
 305                         eem_ss_function, eem_ss_function);
 306         if (status)
 307                 goto fail;
 308
 309         DBG(cdev, "CDC Ethernet (EEM): %s speed IN/%s OUT/%s\n",
 310                         gadget_is_superspeed(c->cdev->gadget) ? "super" :
 311                         gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
 312                         eem->port.in_ep->name, eem->port.out_ep->name);
 313         return 0;
 314
 315 fail:
 316         ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
 317
 318         return status;
 319 }
 320
 321 static void eem_cmd_complete(struct usb_ep *ep, struct usb_request *req)
 322 {
 323         struct sk_buff *skb = (struct sk_buff *)req->context;
 324
 325         dev_kfree_skb_any(skb);
 326 }
 327
 328 /*
 329  * Add the EEM header and ethernet checksum.
 330  * We currently do not attempt to put multiple ethernet frames
 331  * into a single USB transfer
 332  */
 333 static struct sk_buff *eem_wrap(struct gether *port, struct sk_buff *skb)
 334 {
 335         struct sk_buff  *skb2 = NULL;
 336         struct usb_ep   *in = port->in_ep;
 337         int             headroom, tailroom, padlen = 0;
 338         u16             len;
 339
 340         if (!skb)
 341                 return NULL;
 342
 343         len = skb->len;
 344         headroom = skb_headroom(skb);
 345         tailroom = skb_tailroom(skb);
 346
 347         /* When (len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) is 0,
 348          * stick two bytes of zero-length EEM packet on the end.
 349          */
 350         if (((len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) == 0)
 351                 padlen += 2;
 352
 353         if ((tailroom >= (ETH_FCS_LEN + padlen)) &&
 354                         (headroom >= EEM_HLEN) && !skb_cloned(skb))
 355                 goto done;
 356
 357         skb2 = skb_copy_expand(skb, EEM_HLEN, ETH_FCS_LEN + padlen, GFP_ATOMIC);
 358         dev_kfree_skb_any(skb);
 359         skb = skb2;
 360         if (!skb)
 361                 return skb;
 362
 363 done:
 364         /* use the "no CRC" option */
 365         put_unaligned_be32(0xdeadbeef, skb_put(skb, 4));
 366
 367         /* EEM packet header format:
 368          * b0..13:      length of ethernet frame
 369          * b14:         bmCRC (0 == sentinel CRC)
 370          * b15:         bmType (0 == data)
 371          */
 372         len = skb->len;
 373         put_unaligned_le16(len & 0x3FFF, skb_push(skb, 2));
 374
 375         /* add a zero-length EEM packet, if needed */
 376         if (padlen)
 377                 put_unaligned_le16(0, skb_put(skb, 2));
 378
 379         return skb;
 380 }
 381
 382 /*
 383  * Remove the EEM header.  Note that there can be many EEM packets in a single
 384  * USB transfer, so we need to break them out and handle them independently.
 385  */
 386 static int eem_unwrap(struct gether *port,
 387                         struct sk_buff *skb,
 388                         struct sk_buff_head *list)
 389 {
 390         struct usb_composite_dev        *cdev = port->func.config->cdev;
 391         int                             status = 0;
 392
 393         do {
 394                 struct sk_buff  *skb2;
 395                 u16             header;
 396                 u16             len = 0;
 397
 398                 if (skb->len < EEM_HLEN) {
 399                         status = -EINVAL;
 400                         DBG(cdev, "invalid EEM header\n");
 401                         goto error;
 402                 }
 403
 404                 /* remove the EEM header */
 405                 header = get_unaligned_le16(skb->data);
 406                 skb_pull(skb, EEM_HLEN);
 407
 408                 /* EEM packet header format:
 409                  * b0..14:      EEM type dependent (data or command)
 410                  * b15:         bmType (0 == data, 1 == command)
 411                  */
 412                 if (header & BIT(15)) {
 413                         struct usb_request      *req = cdev->req;
 414                         u16                     bmEEMCmd;
 415
 416                         /* EEM command packet format:
 417                          * b0..10:      bmEEMCmdParam
 418                          * b11..13:     bmEEMCmd
 419                          * b14:         reserved (must be zero)
 420                          * b15:         bmType (1 == command)
 421                          */
 422                         if (header & BIT(14))
 423                                 continue;
 424
 425                         bmEEMCmd = (header >> 11) & 0x7;
 426                         switch (bmEEMCmd) {
 427                         case 0: /* echo */
 428                                 len = header & 0x7FF;
 429                                 if (skb->len < len) {
 430                                         status = -EOVERFLOW;
 431                                         goto error;
 432                                 }
 433
 434                                 skb2 = skb_clone(skb, GFP_ATOMIC);
 435                                 if (unlikely(!skb2)) {
 436                                         DBG(cdev, "EEM echo response error\n");
 437                                         goto next;
 438                                 }
 439                                 skb_trim(skb2, len);
 440                                 put_unaligned_le16(BIT(15) | BIT(11) | len,
 441                                                         skb_push(skb2, 2));
 442                                 skb_copy_bits(skb2, 0, req->buf, skb2->len);
 443                                 req->length = skb2->len;
 444                                 req->complete = eem_cmd_complete;
 445                                 req->zero = 1;
 446                                 req->context = skb2;
 447                                 if (usb_ep_queue(port->in_ep, req, GFP_ATOMIC))
 448                                         DBG(cdev, "echo response queue fail\n");
 449                                 break;
 450
 451                         case 1:  /* echo response */
 452                         case 2:  /* suspend hint */
 453                         case 3:  /* response hint */
 454                         case 4:  /* response complete hint */
 455                         case 5:  /* tickle */
 456                         default: /* reserved */
 457                                 continue;
 458                         }
 459                 } else {
 460                         u32             crc, crc2;
 461                         struct sk_buff  *skb3;
 462
 463                         /* check for zero-length EEM packet */
 464                         if (header == 0)
 465                                 continue;
 466
 467                         /* EEM data packet format:
 468                          * b0..13:      length of ethernet frame
 469                          * b14:         bmCRC (0 == sentinel, 1 == calculated)
 470                          * b15:         bmType (0 == data)
 471                          */
 472                         len = header & 0x3FFF;
 473                         if ((skb->len < len)
 474                                         || (len < (ETH_HLEN + ETH_FCS_LEN))) {
 475                                 status = -EINVAL;
 476                                 goto error;
 477                         }
 478
 479                         /* validate CRC */
 480                         if (header & BIT(14)) {
 481                                 crc = get_unaligned_le32(skb->data + len
 482                                                         - ETH_FCS_LEN);
 483                                 crc2 = ~crc32_le(~0,
 484                                                 skb->data, len - ETH_FCS_LEN);
 485                         } else {
 486                                 crc = get_unaligned_be32(skb->data + len
 487                                                         - ETH_FCS_LEN);
 488                                 crc2 = 0xdeadbeef;
 489                         }
 490                         if (crc != crc2) {
 491                                 DBG(cdev, "invalid EEM CRC\n");
 492                                 goto next;
 493                         }
 494
 495                         skb2 = skb_clone(skb, GFP_ATOMIC);
 496                         if (unlikely(!skb2)) {
 497                                 DBG(cdev, "unable to unframe EEM packet\n");
 498                                 goto next;
 499                         }
 500                         skb_trim(skb2, len - ETH_FCS_LEN);
 501
 502                         skb3 = skb_copy_expand(skb2,
 503                                                 NET_IP_ALIGN,
 504                                                 0,
 505                                                 GFP_ATOMIC);
 506                         if (unlikely(!skb3)) {
 507                                 dev_kfree_skb_any(skb2);
 508                                 goto next;
 509                         }
 510                         dev_kfree_skb_any(skb2);
 511                         skb_queue_tail(list, skb3);
 512                 }
 513 next:
 514                 skb_pull(skb, len);
 515         } while (skb->len);
 516
 517 error:
 518         dev_kfree_skb_any(skb);
 519         return status;
 520 }
 521
 522 static inline struct f_eem_opts *to_f_eem_opts(struct config_item *item)
 523 {
 524         return container_of(to_config_group(item), struct f_eem_opts,
 525                             func_inst.group);
 526 }
 527
 528 /* f_eem_item_ops */
 529 USB_ETHERNET_CONFIGFS_ITEM(eem);
 530
 531 /* f_eem_opts_dev_addr */
 532 USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(eem);
 533
 534 /* f_eem_opts_host_addr */
 535 USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(eem);
 536
 537 /* f_eem_opts_qmult */
 538 USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(eem);
 539
 540 /* f_eem_opts_ifname */
 541 USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(eem);
 542
 543 static struct configfs_attribute *eem_attrs[] = {
 544         &eem_opts_attr_dev_addr,
 545         &eem_opts_attr_host_addr,
 546         &eem_opts_attr_qmult,
 547         &eem_opts_attr_ifname,
 548         NULL,
 549 };
 550
 551 static const struct config_item_type eem_func_type = {
 552         .ct_item_ops    = &eem_item_ops,
 553         .ct_attrs       = eem_attrs,
 554         .ct_owner       = THIS_MODULE,
 555 };
 556
 557 static void eem_free_inst(struct usb_function_instance *f)
 558 {
 559         struct f_eem_opts *opts;
 560
 561         opts = container_of(f, struct f_eem_opts, func_inst);
 562         if (opts->bound)
 563                 gether_cleanup(netdev_priv(opts->net));
 564         else
 565                 free_netdev(opts->net);
 566         kfree(opts);
 567 }
 568
 569 static struct usb_function_instance *eem_alloc_inst(void)
 570 {
 571         struct f_eem_opts *opts;
 572
 573         opts = kzalloc(sizeof(*opts), GFP_KERNEL);
 574         if (!opts)
 575                 return ERR_PTR(-ENOMEM);
 576         mutex_init(&opts->lock);
 577         opts->func_inst.free_func_inst = eem_free_inst;
 578         opts->net = gether_setup_default();
 579         if (IS_ERR(opts->net)) {
 580                 struct net_device *net = opts->net;
 581                 kfree(opts);
 582                 return ERR_CAST(net);
 583         }
 584
 585         config_group_init_type_name(&opts->func_inst.group, "", &eem_func_type);
 586
 587         return &opts->func_inst;
 588 }
 589
 590 static void eem_free(struct usb_function *f)
 591 {
 592         struct f_eem *eem;
 593         struct f_eem_opts *opts;
 594
 595         eem = func_to_eem(f);
 596         opts = container_of(f->fi, struct f_eem_opts, func_inst);
 597         kfree(eem);
 598         mutex_lock(&opts->lock);
 599         opts->refcnt--;
 600         mutex_unlock(&opts->lock);
 601 }
 602
 603 static void eem_unbind(struct usb_configuration *c, struct usb_function *f)
 604 {
 605         DBG(c->cdev, "eem unbind\n");
 606
 607         usb_free_all_descriptors(f);
 608 }
 609
 610 static struct usb_function *eem_alloc(struct usb_function_instance *fi)
 611 {
 612         struct f_eem    *eem;
 613         struct f_eem_opts *opts;
 614
 615         /* allocate and initialize one new instance */
 616         eem = kzalloc(sizeof(*eem), GFP_KERNEL);
 617         if (!eem)
 618                 return ERR_PTR(-ENOMEM);
 619
 620         opts = container_of(fi, struct f_eem_opts, func_inst);
 621         mutex_lock(&opts->lock);
 622         opts->refcnt++;
 623
 624         eem->port.ioport = netdev_priv(opts->net);
 625         mutex_unlock(&opts->lock);
 626         eem->port.cdc_filter = DEFAULT_FILTER;
 627
 628         eem->port.func.name = "cdc_eem";
 629         /* descriptors are per-instance copies */
 630         eem->port.func.bind = eem_bind;
 631         eem->port.func.unbind = eem_unbind;
 632         eem->port.func.set_alt = eem_set_alt;
 633         eem->port.func.setup = eem_setup;
 634         eem->port.func.disable = eem_disable;
 635         eem->port.func.free_func = eem_free;
 636         eem->port.wrap = eem_wrap;
 637         eem->port.unwrap = eem_unwrap;
 638         eem->port.header_len = EEM_HLEN;
 639
 640         return &eem->port.func;
 641 }
 642
 643 DECLARE_USB_FUNCTION_INIT(eem, eem_alloc_inst, eem_alloc);
 644 MODULE_LICENSE("GPL");
 645 MODULE_AUTHOR("David Brownell");