drivers/usb/gadget/function/f_eem.c

   1 /*
   2  * f_eem.c -- USB CDC Ethernet (EEM) link function driver
   3  *
   4  * Copyright (C) 2003-2005,2008 David Brownell
   5  * Copyright (C) 2008 Nokia Corporation
   6  * Copyright (C) 2009 EF Johnson Technologies
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/device.h>
  17 #include <linux/etherdevice.h>
  18 #include <linux/crc32.h>
  19 #include <linux/slab.h>
  20
  21 #include "u_ether.h"
  22 #include "u_ether_configfs.h"
  23 #include "u_eem.h"
  24
  25 #define EEM_HLEN 2
  26
  27 /*
  28  * This function is a "CDC Ethernet Emulation Model" (CDC EEM)
  29  * Ethernet link.
  30  */
  31
  32 struct f_eem {
  33         struct gether                   port;
  34         u8                              ctrl_id;
  35 };
  36
  37 static inline struct f_eem *func_to_eem(struct usb_function *f)
  38 {
  39         return container_of(f, struct f_eem, port.func);
  40 }
  41
  42 /*-------------------------------------------------------------------------*/
  43
  44 /* interface descriptor: */
  45
  46 static struct usb_interface_descriptor eem_intf = {
  47         .bLength =              sizeof eem_intf,
  48         .bDescriptorType =      USB_DT_INTERFACE,
  49
  50         /* .bInterfaceNumber = DYNAMIC */
  51         .bNumEndpoints =        2,
  52         .bInterfaceClass =      USB_CLASS_COMM,
  53         .bInterfaceSubClass =   USB_CDC_SUBCLASS_EEM,
  54         .bInterfaceProtocol =   USB_CDC_PROTO_EEM,
  55         /* .iInterface = DYNAMIC */
  56 };
  57
  58 /* full speed support: */
  59
  60 static struct usb_endpoint_descriptor eem_fs_in_desc = {
  61         .bLength =              USB_DT_ENDPOINT_SIZE,
  62         .bDescriptorType =      USB_DT_ENDPOINT,
  63
  64         .bEndpointAddress =     USB_DIR_IN,
  65         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  66 };
  67
  68 static struct usb_endpoint_descriptor eem_fs_out_desc = {
  69         .bLength =              USB_DT_ENDPOINT_SIZE,
  70         .bDescriptorType =      USB_DT_ENDPOINT,
  71
  72         .bEndpointAddress =     USB_DIR_OUT,
  73         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  74 };
  75
  76 static struct usb_descriptor_header *eem_fs_function[] = {
  77         /* CDC EEM control descriptors */
  78         (struct usb_descriptor_header *) &eem_intf,
  79         (struct usb_descriptor_header *) &eem_fs_in_desc,
  80         (struct usb_descriptor_header *) &eem_fs_out_desc,
  81         NULL,
  82 };
  83
  84 /* high speed support: */
  85
  86 static struct usb_endpoint_descriptor eem_hs_in_desc = {
  87         .bLength =              USB_DT_ENDPOINT_SIZE,
  88         .bDescriptorType =      USB_DT_ENDPOINT,
  89
  90         .bEndpointAddress =     USB_DIR_IN,
  91         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  92         .wMaxPacketSize =       cpu_to_le16(512),
  93 };
  94
  95 static struct usb_endpoint_descriptor eem_hs_out_desc = {
  96         .bLength =              USB_DT_ENDPOINT_SIZE,
  97         .bDescriptorType =      USB_DT_ENDPOINT,
  98
  99         .bEndpointAddress =     USB_DIR_OUT,
 100         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 101         .wMaxPacketSize =       cpu_to_le16(512),
 102 };
 103
 104 static struct usb_descriptor_header *eem_hs_function[] = {
 105         /* CDC EEM control descriptors */
 106         (struct usb_descriptor_header *) &eem_intf,
 107         (struct usb_descriptor_header *) &eem_hs_in_desc,
 108         (struct usb_descriptor_header *) &eem_hs_out_desc,
 109         NULL,
 110 };
 111
 112 /* super speed support: */
 113
 114 static struct usb_endpoint_descriptor eem_ss_in_desc = {
 115         .bLength =              USB_DT_ENDPOINT_SIZE,
 116         .bDescriptorType =      USB_DT_ENDPOINT,
 117
 118         .bEndpointAddress =     USB_DIR_IN,
 119         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 120         .wMaxPacketSize =       cpu_to_le16(1024),
 121 };
 122
 123 static struct usb_endpoint_descriptor eem_ss_out_desc = {
 124         .bLength =              USB_DT_ENDPOINT_SIZE,
 125         .bDescriptorType =      USB_DT_ENDPOINT,
 126
 127         .bEndpointAddress =     USB_DIR_OUT,
 128         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 129         .wMaxPacketSize =       cpu_to_le16(1024),
 130 };
 131
 132 static struct usb_ss_ep_comp_descriptor eem_ss_bulk_comp_desc = {
 133         .bLength =              sizeof eem_ss_bulk_comp_desc,
 134         .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
 135
 136         /* the following 2 values can be tweaked if necessary */
 137         /* .bMaxBurst =         0, */
 138         /* .bmAttributes =      0, */
 139 };
 140
 141 static struct usb_descriptor_header *eem_ss_function[] = {
 142         /* CDC EEM control descriptors */
 143         (struct usb_descriptor_header *) &eem_intf,
 144         (struct usb_descriptor_header *) &eem_ss_in_desc,
 145         (struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
 146         (struct usb_descriptor_header *) &eem_ss_out_desc,
 147         (struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
 148         NULL,
 149 };
 150
 151 /* string descriptors: */
 152
 153 static struct usb_string eem_string_defs[] = {
 154         [0].s = "CDC Ethernet Emulation Model (EEM)",
 155         {  } /* end of list */
 156 };
 157
 158 static struct usb_gadget_strings eem_string_table = {
 159         .language =             0x0409, /* en-us */
 160         .strings =              eem_string_defs,
 161 };
 162
 163 static struct usb_gadget_strings *eem_strings[] = {
 164         &eem_string_table,
 165         NULL,
 166 };
 167
 168 /*-------------------------------------------------------------------------*/
 169
 170 static int eem_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
 171 {
 172         struct usb_composite_dev *cdev = f->config->cdev;
 173         int                     value = -EOPNOTSUPP;
 174         u16                     w_index = le16_to_cpu(ctrl->wIndex);
 175         u16                     w_value = le16_to_cpu(ctrl->wValue);
 176         u16                     w_length = le16_to_cpu(ctrl->wLength);
 177
 178         DBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
 179                 ctrl->bRequestType, ctrl->bRequest,
 180                 w_value, w_index, w_length);
 181
 182         /* device either stalls (value < 0) or reports success */
 183         return value;
 184 }
 185
 186
 187 static int eem_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 188 {
 189         struct f_eem            *eem = func_to_eem(f);
 190         struct usb_composite_dev *cdev = f->config->cdev;
 191         struct net_device       *net;
 192
 193         /* we know alt == 0, so this is an activation or a reset */
 194         if (alt != 0)
 195                 goto fail;
 196
 197         if (intf == eem->ctrl_id) {
 198                 DBG(cdev, "reset eem\n");
 199                 gether_disconnect(&eem->port);
 200
 201                 if (!eem->port.in_ep->desc || !eem->port.out_ep->desc) {
 202                         DBG(cdev, "init eem\n");
 203                         if (config_ep_by_speed(cdev->gadget, f,
 204                                                eem->port.in_ep) ||
 205                             config_ep_by_speed(cdev->gadget, f,
 206                                                eem->port.out_ep)) {
 207                                 eem->port.in_ep->desc = NULL;
 208                                 eem->port.out_ep->desc = NULL;
 209                                 goto fail;
 210                         }
 211                 }
 212
 213                 /* zlps should not occur because zero-length EEM packets
 214                  * will be inserted in those cases where they would occur
 215                  */
 216                 eem->port.is_zlp_ok = 1;
 217                 eem->port.cdc_filter = DEFAULT_FILTER;
 218                 DBG(cdev, "activate eem\n");
 219                 net = gether_connect(&eem->port);
 220                 if (IS_ERR(net))
 221                         return PTR_ERR(net);
 222         } else
 223                 goto fail;
 224
 225         return 0;
 226 fail:
 227         return -EINVAL;
 228 }
 229
 230 static void eem_disable(struct usb_function *f)
 231 {
 232         struct f_eem            *eem = func_to_eem(f);
 233         struct usb_composite_dev *cdev = f->config->cdev;
 234
 235         DBG(cdev, "eem deactivated\n");
 236
 237         if (eem->port.in_ep->enabled)
 238                 gether_disconnect(&eem->port);
 239 }
 240
 241 /*-------------------------------------------------------------------------*/
 242
 243 /* EEM function driver setup/binding */
 244
 245 static int eem_bind(struct usb_configuration *c, struct usb_function *f)
 246 {
 247         struct usb_composite_dev *cdev = c->cdev;
 248         struct f_eem            *eem = func_to_eem(f);
 249         struct usb_string       *us;
 250         int                     status;
 251         struct usb_ep           *ep;
 252
 253         struct f_eem_opts       *eem_opts;
 254
 255         eem_opts = container_of(f->fi, struct f_eem_opts, func_inst);
 256         /*
 257          * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
 258          * configurations are bound in sequence with list_for_each_entry,
 259          * in each configuration its functions are bound in sequence
 260          * with list_for_each_entry, so we assume no race condition
 261          * with regard to eem_opts->bound access
 262          */
 263         if (!eem_opts->bound) {
 264                 mutex_lock(&eem_opts->lock);
 265                 gether_set_gadget(eem_opts->net, cdev->gadget);
 266                 status = gether_register_netdev(eem_opts->net);
 267                 mutex_unlock(&eem_opts->lock);
 268                 if (status)
 269                         return status;
 270                 eem_opts->bound = true;
 271         }
 272
 273         us = usb_gstrings_attach(cdev, eem_strings,
 274                                  ARRAY_SIZE(eem_string_defs));
 275         if (IS_ERR(us))
 276                 return PTR_ERR(us);
 277         eem_intf.iInterface = us[0].id;
 278
 279         /* allocate instance-specific interface IDs */
 280         status = usb_interface_id(c, f);
 281         if (status < 0)
 282                 goto fail;
 283         eem->ctrl_id = status;
 284         eem_intf.bInterfaceNumber = status;
 285
 286         status = -ENODEV;
 287
 288         /* allocate instance-specific endpoints */
 289         ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_in_desc);
 290         if (!ep)
 291                 goto fail;
 292         eem->port.in_ep = ep;
 293
 294         ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_out_desc);
 295         if (!ep)
 296                 goto fail;
 297         eem->port.out_ep = ep;
 298
 299         status = -ENOMEM;
 300
 301         /* support all relevant hardware speeds... we expect that when
 302          * hardware is dual speed, all bulk-capable endpoints work at
 303          * both speeds
 304          */
 305         eem_hs_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
 306         eem_hs_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
 307
 308         eem_ss_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
 309         eem_ss_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
 310
 311         status = usb_assign_descriptors(f, eem_fs_function, eem_hs_function,
 312                         eem_ss_function);
 313         if (status)
 314                 goto fail;
 315
 316         DBG(cdev, "CDC Ethernet (EEM): %s speed IN/%s OUT/%s\n",
 317                         gadget_is_superspeed(c->cdev->gadget) ? "super" :
 318                         gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
 319                         eem->port.in_ep->name, eem->port.out_ep->name);
 320         return 0;
 321
 322 fail:
 323         ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
 324
 325         return status;
 326 }
 327
 328 static void eem_cmd_complete(struct usb_ep *ep, struct usb_request *req)
 329 {
 330         struct sk_buff *skb = (struct sk_buff *)req->context;
 331
 332         dev_kfree_skb_any(skb);
 333 }
 334
 335 /*
 336  * Add the EEM header and ethernet checksum.
 337  * We currently do not attempt to put multiple ethernet frames
 338  * into a single USB transfer
 339  */
 340 static struct sk_buff *eem_wrap(struct gether *port, struct sk_buff *skb)
 341 {
 342         struct sk_buff  *skb2 = NULL;
 343         struct usb_ep   *in = port->in_ep;
 344         int             padlen = 0;
 345         u16             len = skb->len;
 346
 347         int headroom = skb_headroom(skb);
 348         int 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                                 DBG(cdev, "unable to realign EEM packet\n");
 511                                 dev_kfree_skb_any(skb2);
 512                                 continue;
 513                         }
 514                         dev_kfree_skb_any(skb2);
 515                         skb_queue_tail(list, skb3);
 516                 }
 517 next:
 518                 skb_pull(skb, len);
 519         } while (skb->len);
 520
 521 error:
 522         dev_kfree_skb_any(skb);
 523         return status;
 524 }
 525
 526 static inline struct f_eem_opts *to_f_eem_opts(struct config_item *item)
 527 {
 528         return container_of(to_config_group(item), struct f_eem_opts,
 529                             func_inst.group);
 530 }
 531
 532 /* f_eem_item_ops */
 533 USB_ETHERNET_CONFIGFS_ITEM(eem);
 534
 535 /* f_eem_opts_dev_addr */
 536 USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(eem);
 537
 538 /* f_eem_opts_host_addr */
 539 USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(eem);
 540
 541 /* f_eem_opts_qmult */
 542 USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(eem);
 543
 544 /* f_eem_opts_ifname */
 545 USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(eem);
 546
 547 static struct configfs_attribute *eem_attrs[] = {
 548         &eem_opts_attr_dev_addr,
 549         &eem_opts_attr_host_addr,
 550         &eem_opts_attr_qmult,
 551         &eem_opts_attr_ifname,
 552         NULL,
 553 };
 554
 555 static struct config_item_type eem_func_type = {
 556         .ct_item_ops    = &eem_item_ops,
 557         .ct_attrs       = eem_attrs,
 558         .ct_owner       = THIS_MODULE,
 559 };
 560
 561 static void eem_free_inst(struct usb_function_instance *f)
 562 {
 563         struct f_eem_opts *opts;
 564
 565         opts = container_of(f, struct f_eem_opts, func_inst);
 566         if (opts->bound)
 567                 gether_cleanup(netdev_priv(opts->net));
 568         else
 569                 free_netdev(opts->net);
 570         kfree(opts);
 571 }
 572
 573 static struct usb_function_instance *eem_alloc_inst(void)
 574 {
 575         struct f_eem_opts *opts;
 576
 577         opts = kzalloc(sizeof(*opts), GFP_KERNEL);
 578         if (!opts)
 579                 return ERR_PTR(-ENOMEM);
 580         mutex_init(&opts->lock);
 581         opts->func_inst.free_func_inst = eem_free_inst;
 582         opts->net = gether_setup_default();
 583         if (IS_ERR(opts->net)) {
 584                 struct net_device *net = opts->net;
 585                 kfree(opts);
 586                 return ERR_CAST(net);
 587         }
 588
 589         config_group_init_type_name(&opts->func_inst.group, "", &eem_func_type);
 590
 591         return &opts->func_inst;
 592 }
 593
 594 static void eem_free(struct usb_function *f)
 595 {
 596         struct f_eem *eem;
 597         struct f_eem_opts *opts;
 598
 599         eem = func_to_eem(f);
 600         opts = container_of(f->fi, struct f_eem_opts, func_inst);
 601         kfree(eem);
 602         mutex_lock(&opts->lock);
 603         opts->refcnt--;
 604         mutex_unlock(&opts->lock);
 605 }
 606
 607 static void eem_unbind(struct usb_configuration *c, struct usb_function *f)
 608 {
 609         DBG(c->cdev, "eem unbind\n");
 610
 611         usb_free_all_descriptors(f);
 612 }
 613
 614 static struct usb_function *eem_alloc(struct usb_function_instance *fi)
 615 {
 616         struct f_eem    *eem;
 617         struct f_eem_opts *opts;
 618
 619         /* allocate and initialize one new instance */
 620         eem = kzalloc(sizeof(*eem), GFP_KERNEL);
 621         if (!eem)
 622                 return ERR_PTR(-ENOMEM);
 623
 624         opts = container_of(fi, struct f_eem_opts, func_inst);
 625         mutex_lock(&opts->lock);
 626         opts->refcnt++;
 627
 628         eem->port.ioport = netdev_priv(opts->net);
 629         mutex_unlock(&opts->lock);
 630         eem->port.cdc_filter = DEFAULT_FILTER;
 631
 632         eem->port.func.name = "cdc_eem";
 633         /* descriptors are per-instance copies */
 634         eem->port.func.bind = eem_bind;
 635         eem->port.func.unbind = eem_unbind;
 636         eem->port.func.set_alt = eem_set_alt;
 637         eem->port.func.setup = eem_setup;
 638         eem->port.func.disable = eem_disable;
 639         eem->port.func.free_func = eem_free;
 640         eem->port.wrap = eem_wrap;
 641         eem->port.unwrap = eem_unwrap;
 642         eem->port.header_len = EEM_HLEN;
 643
 644         return &eem->port.func;
 645 }
 646
 647 DECLARE_USB_FUNCTION_INIT(eem, eem_alloc_inst, eem_alloc);
 648 MODULE_LICENSE("GPL");
 649 MODULE_AUTHOR("David Brownell");