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         int                     value = -EOPNOTSUPP;
 170         u16                     w_index = le16_to_cpu(ctrl->wIndex);
 171         u16                     w_value = le16_to_cpu(ctrl->wValue);
 172         u16                     w_length = le16_to_cpu(ctrl->wLength);
 173
 174         DBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
 175                 ctrl->bRequestType, ctrl->bRequest,
 176                 w_value, w_index, w_length);
 177
 178         /* device either stalls (value < 0) or reports success */
 179         return value;
 180 }
 181
 182
 183 static int eem_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 184 {
 185         struct f_eem            *eem = func_to_eem(f);
 186         struct usb_composite_dev *cdev = f->config->cdev;
 187         struct net_device       *net;
 188
 189         /* we know alt == 0, so this is an activation or a reset */
 190         if (alt != 0)
 191                 goto fail;
 192
 193         if (intf == eem->ctrl_id) {
 194                 DBG(cdev, "reset eem\n");
 195                 gether_disconnect(&eem->port);
 196
 197                 if (!eem->port.in_ep->desc || !eem->port.out_ep->desc) {
 198                         DBG(cdev, "init eem\n");
 199                         if (config_ep_by_speed(cdev->gadget, f,
 200                                                eem->port.in_ep) ||
 201                             config_ep_by_speed(cdev->gadget, f,
 202                                                eem->port.out_ep)) {
 203                                 eem->port.in_ep->desc = NULL;
 204                                 eem->port.out_ep->desc = NULL;
 205                                 goto fail;
 206                         }
 207                 }
 208
 209                 /* zlps should not occur because zero-length EEM packets
 210                  * will be inserted in those cases where they would occur
 211                  */
 212                 eem->port.is_zlp_ok = 1;
 213                 eem->port.cdc_filter = DEFAULT_FILTER;
 214                 DBG(cdev, "activate eem\n");
 215                 net = gether_connect(&eem->port);
 216                 if (IS_ERR(net))
 217                         return PTR_ERR(net);
 218         } else
 219                 goto fail;
 220
 221         return 0;
 222 fail:
 223         return -EINVAL;
 224 }
 225
 226 static void eem_disable(struct usb_function *f)
 227 {
 228         struct f_eem            *eem = func_to_eem(f);
 229         struct usb_composite_dev *cdev = f->config->cdev;
 230
 231         DBG(cdev, "eem deactivated\n");
 232
 233         if (eem->port.in_ep->enabled)
 234                 gether_disconnect(&eem->port);
 235 }
 236
 237 /*-------------------------------------------------------------------------*/
 238
 239 /* EEM function driver setup/binding */
 240
 241 static int eem_bind(struct usb_configuration *c, struct usb_function *f)
 242 {
 243         struct usb_composite_dev *cdev = c->cdev;
 244         struct f_eem            *eem = func_to_eem(f);
 245         struct usb_string       *us;
 246         int                     status;
 247         struct usb_ep           *ep;
 248
 249         struct f_eem_opts       *eem_opts;
 250
 251         eem_opts = container_of(f->fi, struct f_eem_opts, func_inst);
 252         /*
 253          * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
 254          * configurations are bound in sequence with list_for_each_entry,
 255          * in each configuration its functions are bound in sequence
 256          * with list_for_each_entry, so we assume no race condition
 257          * with regard to eem_opts->bound access
 258          */
 259         if (!eem_opts->bound) {
 260                 mutex_lock(&eem_opts->lock);
 261                 gether_set_gadget(eem_opts->net, cdev->gadget);
 262                 status = gether_register_netdev(eem_opts->net);
 263                 mutex_unlock(&eem_opts->lock);
 264                 if (status)
 265                         return status;
 266                 eem_opts->bound = true;
 267         }
 268
 269         us = usb_gstrings_attach(cdev, eem_strings,
 270                                  ARRAY_SIZE(eem_string_defs));
 271         if (IS_ERR(us))
 272                 return PTR_ERR(us);
 273         eem_intf.iInterface = us[0].id;
 274
 275         /* allocate instance-specific interface IDs */
 276         status = usb_interface_id(c, f);
 277         if (status < 0)
 278                 goto fail;
 279         eem->ctrl_id = status;
 280         eem_intf.bInterfaceNumber = status;
 281
 282         status = -ENODEV;
 283
 284         /* allocate instance-specific endpoints */
 285         ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_in_desc);
 286         if (!ep)
 287                 goto fail;
 288         eem->port.in_ep = ep;
 289
 290         ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_out_desc);
 291         if (!ep)
 292                 goto fail;
 293         eem->port.out_ep = ep;
 294
 295         status = -ENOMEM;
 296
 297         /* support all relevant hardware speeds... we expect that when
 298          * hardware is dual speed, all bulk-capable endpoints work at
 299          * both speeds
 300          */
 301         eem_hs_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
 302         eem_hs_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
 303
 304         eem_ss_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
 305         eem_ss_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
 306
 307         status = usb_assign_descriptors(f, eem_fs_function, eem_hs_function,
 308                         eem_ss_function, NULL);
 309         if (status)
 310                 goto fail;
 311
 312         DBG(cdev, "CDC Ethernet (EEM): %s speed IN/%s OUT/%s\n",
 313                         gadget_is_superspeed(c->cdev->gadget) ? "super" :
 314                         gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
 315                         eem->port.in_ep->name, eem->port.out_ep->name);
 316         return 0;
 317
 318 fail:
 319         ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
 320
 321         return status;
 322 }
 323
 324 static void eem_cmd_complete(struct usb_ep *ep, struct usb_request *req)
 325 {
 326         struct sk_buff *skb = (struct sk_buff *)req->context;
 327
 328         dev_kfree_skb_any(skb);
 329 }
 330
 331 /*
 332  * Add the EEM header and ethernet checksum.
 333  * We currently do not attempt to put multiple ethernet frames
 334  * into a single USB transfer
 335  */
 336 static struct sk_buff *eem_wrap(struct gether *port, struct sk_buff *skb)
 337 {
 338         struct sk_buff  *skb2 = NULL;
 339         struct usb_ep   *in = port->in_ep;
 340         int             headroom, tailroom, padlen = 0;
 341         u16             len;
 342
 343         if (!skb)
 344                 return NULL;
 345
 346         len = skb->len;
 347         headroom = skb_headroom(skb);
 348         tailroom = skb_tailroom(skb);
 349
 350         /* When (len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) is 0,
 351          * stick two bytes of zero-length EEM packet on the end.
 352          */
 353         if (((len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) == 0)
 354                 padlen += 2;
 355
 356         if ((tailroom >= (ETH_FCS_LEN + padlen)) &&
 357                         (headroom >= EEM_HLEN) && !skb_cloned(skb))
 358                 goto done;
 359
 360         skb2 = skb_copy_expand(skb, EEM_HLEN, ETH_FCS_LEN + padlen, GFP_ATOMIC);
 361         dev_kfree_skb_any(skb);
 362         skb = skb2;
 363         if (!skb)
 364                 return skb;
 365
 366 done:
 367         /* use the "no CRC" option */
 368         put_unaligned_be32(0xdeadbeef, skb_put(skb, 4));
 369
 370         /* EEM packet header format:
 371          * b0..13:      length of ethernet frame
 372          * b14:         bmCRC (0 == sentinel CRC)
 373          * b15:         bmType (0 == data)
 374          */
 375         len = skb->len;
 376         put_unaligned_le16(len & 0x3FFF, skb_push(skb, 2));
 377
 378         /* add a zero-length EEM packet, if needed */
 379         if (padlen)
 380                 put_unaligned_le16(0, skb_put(skb, 2));
 381
 382         return skb;
 383 }
 384
 385 /*
 386  * Remove the EEM header.  Note that there can be many EEM packets in a single
 387  * USB transfer, so we need to break them out and handle them independently.
 388  */
 389 static int eem_unwrap(struct gether *port,
 390                         struct sk_buff *skb,
 391                         struct sk_buff_head *list)
 392 {
 393         struct usb_composite_dev        *cdev = port->func.config->cdev;
 394         int                             status = 0;
 395
 396         do {
 397                 struct sk_buff  *skb2;
 398                 u16             header;
 399                 u16             len = 0;
 400
 401                 if (skb->len < EEM_HLEN) {
 402                         status = -EINVAL;
 403                         DBG(cdev, "invalid EEM header\n");
 404                         goto error;
 405                 }
 406
 407                 /* remove the EEM header */
 408                 header = get_unaligned_le16(skb->data);
 409                 skb_pull(skb, EEM_HLEN);
 410
 411                 /* EEM packet header format:
 412                  * b0..14:      EEM type dependent (data or command)
 413                  * b15:         bmType (0 == data, 1 == command)
 414                  */
 415                 if (header & BIT(15)) {
 416                         struct usb_request      *req = cdev->req;
 417                         u16                     bmEEMCmd;
 418
 419                         /* EEM command packet format:
 420                          * b0..10:      bmEEMCmdParam
 421                          * b11..13:     bmEEMCmd
 422                          * b14:         reserved (must be zero)
 423                          * b15:         bmType (1 == command)
 424                          */
 425                         if (header & BIT(14))
 426                                 continue;
 427
 428                         bmEEMCmd = (header >> 11) & 0x7;
 429                         switch (bmEEMCmd) {
 430                         case 0: /* echo */
 431                                 len = header & 0x7FF;
 432                                 if (skb->len < len) {
 433                                         status = -EOVERFLOW;
 434                                         goto error;
 435                                 }
 436
 437                                 skb2 = skb_clone(skb, GFP_ATOMIC);
 438                                 if (unlikely(!skb2)) {
 439                                         DBG(cdev, "EEM echo response error\n");
 440                                         goto next;
 441                                 }
 442                                 skb_trim(skb2, len);
 443                                 put_unaligned_le16(BIT(15) | BIT(11) | len,
 444                                                         skb_push(skb2, 2));
 445                                 skb_copy_bits(skb2, 0, req->buf, skb2->len);
 446                                 req->length = skb2->len;
 447                                 req->complete = eem_cmd_complete;
 448                                 req->zero = 1;
 449                                 req->context = skb2;
 450                                 if (usb_ep_queue(port->in_ep, req, GFP_ATOMIC))
 451                                         DBG(cdev, "echo response queue fail\n");
 452                                 break;
 453
 454                         case 1:  /* echo response */
 455                         case 2:  /* suspend hint */
 456                         case 3:  /* response hint */
 457                         case 4:  /* response complete hint */
 458                         case 5:  /* tickle */
 459                         default: /* reserved */
 460                                 continue;
 461                         }
 462                 } else {
 463                         u32             crc, crc2;
 464                         struct sk_buff  *skb3;
 465
 466                         /* check for zero-length EEM packet */
 467                         if (header == 0)
 468                                 continue;
 469
 470                         /* EEM data packet format:
 471                          * b0..13:      length of ethernet frame
 472                          * b14:         bmCRC (0 == sentinel, 1 == calculated)
 473                          * b15:         bmType (0 == data)
 474                          */
 475                         len = header & 0x3FFF;
 476                         if ((skb->len < len)
 477                                         || (len < (ETH_HLEN + ETH_FCS_LEN))) {
 478                                 status = -EINVAL;
 479                                 goto error;
 480                         }
 481
 482                         /* validate CRC */
 483                         if (header & BIT(14)) {
 484                                 crc = get_unaligned_le32(skb->data + len
 485                                                         - ETH_FCS_LEN);
 486                                 crc2 = ~crc32_le(~0,
 487                                                 skb->data, len - ETH_FCS_LEN);
 488                         } else {
 489                                 crc = get_unaligned_be32(skb->data + len
 490                                                         - ETH_FCS_LEN);
 491                                 crc2 = 0xdeadbeef;
 492                         }
 493                         if (crc != crc2) {
 494                                 DBG(cdev, "invalid EEM CRC\n");
 495                                 goto next;
 496                         }
 497
 498                         skb2 = skb_clone(skb, GFP_ATOMIC);
 499                         if (unlikely(!skb2)) {
 500                                 DBG(cdev, "unable to unframe EEM packet\n");
 501                                 continue;
 502                         }
 503                         skb_trim(skb2, len - ETH_FCS_LEN);
 504
 505                         skb3 = skb_copy_expand(skb2,
 506                                                 NET_IP_ALIGN,
 507                                                 0,
 508                                                 GFP_ATOMIC);
 509                         if (unlikely(!skb3)) {
 510                                 dev_kfree_skb_any(skb2);
 511                                 continue;
 512                         }
 513                         dev_kfree_skb_any(skb2);
 514                         skb_queue_tail(list, skb3);
 515                 }
 516 next:
 517                 skb_pull(skb, len);
 518         } while (skb->len);
 519
 520 error:
 521         dev_kfree_skb_any(skb);
 522         return status;
 523 }
 524
 525 static inline struct f_eem_opts *to_f_eem_opts(struct config_item *item)
 526 {
 527         return container_of(to_config_group(item), struct f_eem_opts,
 528                             func_inst.group);
 529 }
 530
 531 /* f_eem_item_ops */
 532 USB_ETHERNET_CONFIGFS_ITEM(eem);
 533
 534 /* f_eem_opts_dev_addr */
 535 USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(eem);
 536
 537 /* f_eem_opts_host_addr */
 538 USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(eem);
 539
 540 /* f_eem_opts_qmult */
 541 USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(eem);
 542
 543 /* f_eem_opts_ifname */
 544 USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(eem);
 545
 546 static struct configfs_attribute *eem_attrs[] = {
 547         &eem_opts_attr_dev_addr,
 548         &eem_opts_attr_host_addr,
 549         &eem_opts_attr_qmult,
 550         &eem_opts_attr_ifname,
 551         NULL,
 552 };
 553
 554 static const struct config_item_type eem_func_type = {
 555         .ct_item_ops    = &eem_item_ops,
 556         .ct_attrs       = eem_attrs,
 557         .ct_owner       = THIS_MODULE,
 558 };
 559
 560 static void eem_free_inst(struct usb_function_instance *f)
 561 {
 562         struct f_eem_opts *opts;
 563
 564         opts = container_of(f, struct f_eem_opts, func_inst);
 565         if (opts->bound)
 566                 gether_cleanup(netdev_priv(opts->net));
 567         else
 568                 free_netdev(opts->net);
 569         kfree(opts);
 570 }
 571
 572 static struct usb_function_instance *eem_alloc_inst(void)
 573 {
 574         struct f_eem_opts *opts;
 575
 576         opts = kzalloc(sizeof(*opts), GFP_KERNEL);
 577         if (!opts)
 578                 return ERR_PTR(-ENOMEM);
 579         mutex_init(&opts->lock);
 580         opts->func_inst.free_func_inst = eem_free_inst;
 581         opts->net = gether_setup_default();
 582         if (IS_ERR(opts->net)) {
 583                 struct net_device *net = opts->net;
 584                 kfree(opts);
 585                 return ERR_CAST(net);
 586         }
 587
 588         config_group_init_type_name(&opts->func_inst.group, "", &eem_func_type);
 589
 590         return &opts->func_inst;
 591 }
 592
 593 static void eem_free(struct usb_function *f)
 594 {
 595         struct f_eem *eem;
 596         struct f_eem_opts *opts;
 597
 598         eem = func_to_eem(f);
 599         opts = container_of(f->fi, struct f_eem_opts, func_inst);
 600         kfree(eem);
 601         mutex_lock(&opts->lock);
 602         opts->refcnt--;
 603         mutex_unlock(&opts->lock);
 604 }
 605
 606 static void eem_unbind(struct usb_configuration *c, struct usb_function *f)
 607 {
 608         DBG(c->cdev, "eem unbind\n");
 609
 610         usb_free_all_descriptors(f);
 611 }
 612
 613 static struct usb_function *eem_alloc(struct usb_function_instance *fi)
 614 {
 615         struct f_eem    *eem;
 616         struct f_eem_opts *opts;
 617
 618         /* allocate and initialize one new instance */
 619         eem = kzalloc(sizeof(*eem), GFP_KERNEL);
 620         if (!eem)
 621                 return ERR_PTR(-ENOMEM);
 622
 623         opts = container_of(fi, struct f_eem_opts, func_inst);
 624         mutex_lock(&opts->lock);
 625         opts->refcnt++;
 626
 627         eem->port.ioport = netdev_priv(opts->net);
 628         mutex_unlock(&opts->lock);
 629         eem->port.cdc_filter = DEFAULT_FILTER;
 630
 631         eem->port.func.name = "cdc_eem";
 632         /* descriptors are per-instance copies */
 633         eem->port.func.bind = eem_bind;
 634         eem->port.func.unbind = eem_unbind;
 635         eem->port.func.set_alt = eem_set_alt;
 636         eem->port.func.setup = eem_setup;
 637         eem->port.func.disable = eem_disable;
 638         eem->port.func.free_func = eem_free;
 639         eem->port.wrap = eem_wrap;
 640         eem->port.unwrap = eem_unwrap;
 641         eem->port.header_len = EEM_HLEN;
 642
 643         return &eem->port.func;
 644 }
 645
 646 DECLARE_USB_FUNCTION_INIT(eem, eem_alloc_inst, eem_alloc);
 647 MODULE_LICENSE("GPL");
 648 MODULE_AUTHOR("David Brownell");