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 struct in_context {
  34         struct sk_buff  *skb;
  35         struct usb_ep   *ep;
  36 };
  37
  38 static inline struct f_eem *func_to_eem(struct usb_function *f)
  39 {
  40         return container_of(f, struct f_eem, port.func);
  41 }
  42
  43 /*-------------------------------------------------------------------------*/
  44
  45 /* interface descriptor: */
  46
  47 static struct usb_interface_descriptor eem_intf = {
  48         .bLength =              sizeof eem_intf,
  49         .bDescriptorType =      USB_DT_INTERFACE,
  50
  51         /* .bInterfaceNumber = DYNAMIC */
  52         .bNumEndpoints =        2,
  53         .bInterfaceClass =      USB_CLASS_COMM,
  54         .bInterfaceSubClass =   USB_CDC_SUBCLASS_EEM,
  55         .bInterfaceProtocol =   USB_CDC_PROTO_EEM,
  56         /* .iInterface = DYNAMIC */
  57 };
  58
  59 /* full speed support: */
  60
  61 static struct usb_endpoint_descriptor eem_fs_in_desc = {
  62         .bLength =              USB_DT_ENDPOINT_SIZE,
  63         .bDescriptorType =      USB_DT_ENDPOINT,
  64
  65         .bEndpointAddress =     USB_DIR_IN,
  66         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  67 };
  68
  69 static struct usb_endpoint_descriptor eem_fs_out_desc = {
  70         .bLength =              USB_DT_ENDPOINT_SIZE,
  71         .bDescriptorType =      USB_DT_ENDPOINT,
  72
  73         .bEndpointAddress =     USB_DIR_OUT,
  74         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  75 };
  76
  77 static struct usb_descriptor_header *eem_fs_function[] = {
  78         /* CDC EEM control descriptors */
  79         (struct usb_descriptor_header *) &eem_intf,
  80         (struct usb_descriptor_header *) &eem_fs_in_desc,
  81         (struct usb_descriptor_header *) &eem_fs_out_desc,
  82         NULL,
  83 };
  84
  85 /* high speed support: */
  86
  87 static struct usb_endpoint_descriptor eem_hs_in_desc = {
  88         .bLength =              USB_DT_ENDPOINT_SIZE,
  89         .bDescriptorType =      USB_DT_ENDPOINT,
  90
  91         .bEndpointAddress =     USB_DIR_IN,
  92         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  93         .wMaxPacketSize =       cpu_to_le16(512),
  94 };
  95
  96 static struct usb_endpoint_descriptor eem_hs_out_desc = {
  97         .bLength =              USB_DT_ENDPOINT_SIZE,
  98         .bDescriptorType =      USB_DT_ENDPOINT,
  99
 100         .bEndpointAddress =     USB_DIR_OUT,
 101         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 102         .wMaxPacketSize =       cpu_to_le16(512),
 103 };
 104
 105 static struct usb_descriptor_header *eem_hs_function[] = {
 106         /* CDC EEM control descriptors */
 107         (struct usb_descriptor_header *) &eem_intf,
 108         (struct usb_descriptor_header *) &eem_hs_in_desc,
 109         (struct usb_descriptor_header *) &eem_hs_out_desc,
 110         NULL,
 111 };
 112
 113 /* super speed support: */
 114
 115 static struct usb_endpoint_descriptor eem_ss_in_desc = {
 116         .bLength =              USB_DT_ENDPOINT_SIZE,
 117         .bDescriptorType =      USB_DT_ENDPOINT,
 118
 119         .bEndpointAddress =     USB_DIR_IN,
 120         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 121         .wMaxPacketSize =       cpu_to_le16(1024),
 122 };
 123
 124 static struct usb_endpoint_descriptor eem_ss_out_desc = {
 125         .bLength =              USB_DT_ENDPOINT_SIZE,
 126         .bDescriptorType =      USB_DT_ENDPOINT,
 127
 128         .bEndpointAddress =     USB_DIR_OUT,
 129         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 130         .wMaxPacketSize =       cpu_to_le16(1024),
 131 };
 132
 133 static struct usb_ss_ep_comp_descriptor eem_ss_bulk_comp_desc = {
 134         .bLength =              sizeof eem_ss_bulk_comp_desc,
 135         .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
 136
 137         /* the following 2 values can be tweaked if necessary */
 138         /* .bMaxBurst =         0, */
 139         /* .bmAttributes =      0, */
 140 };
 141
 142 static struct usb_descriptor_header *eem_ss_function[] = {
 143         /* CDC EEM control descriptors */
 144         (struct usb_descriptor_header *) &eem_intf,
 145         (struct usb_descriptor_header *) &eem_ss_in_desc,
 146         (struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
 147         (struct usb_descriptor_header *) &eem_ss_out_desc,
 148         (struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
 149         NULL,
 150 };
 151
 152 /* string descriptors: */
 153
 154 static struct usb_string eem_string_defs[] = {
 155         [0].s = "CDC Ethernet Emulation Model (EEM)",
 156         {  } /* end of list */
 157 };
 158
 159 static struct usb_gadget_strings eem_string_table = {
 160         .language =             0x0409, /* en-us */
 161         .strings =              eem_string_defs,
 162 };
 163
 164 static struct usb_gadget_strings *eem_strings[] = {
 165         &eem_string_table,
 166         NULL,
 167 };
 168
 169 /*-------------------------------------------------------------------------*/
 170
 171 static int eem_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
 172 {
 173         struct usb_composite_dev *cdev = f->config->cdev;
 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 -EOPNOTSUPP;
 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         /* support all relevant hardware speeds... we expect that when
 300          * hardware is dual speed, all bulk-capable endpoints work at
 301          * both speeds
 302          */
 303         eem_hs_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
 304         eem_hs_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
 305
 306         eem_ss_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
 307         eem_ss_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
 308
 309         status = usb_assign_descriptors(f, eem_fs_function, eem_hs_function,
 310                         eem_ss_function, eem_ss_function);
 311         if (status)
 312                 goto fail;
 313
 314         DBG(cdev, "CDC Ethernet (EEM): IN/%s OUT/%s\n",
 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 in_context *ctx = req->context;
 327
 328         dev_kfree_skb_any(ctx->skb);
 329         kfree(req->buf);
 330         usb_ep_free_request(ctx->ep, req);
 331         kfree(ctx);
 332 }
 333
 334 /*
 335  * Add the EEM header and ethernet checksum.
 336  * We currently do not attempt to put multiple ethernet frames
 337  * into a single USB transfer
 338  */
 339 static struct sk_buff *eem_wrap(struct gether *port, struct sk_buff *skb)
 340 {
 341         struct sk_buff  *skb2 = NULL;
 342         struct usb_ep   *in = port->in_ep;
 343         int             headroom, tailroom, padlen = 0;
 344         u16             len;
 345
 346         if (!skb)
 347                 return NULL;
 348
 349         len = skb->len;
 350         headroom = skb_headroom(skb);
 351         tailroom = skb_tailroom(skb);
 352
 353         /* When (len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) is 0,
 354          * stick two bytes of zero-length EEM packet on the end.
 355          */
 356         if (((len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) == 0)
 357                 padlen += 2;
 358
 359         if ((tailroom >= (ETH_FCS_LEN + padlen)) &&
 360                         (headroom >= EEM_HLEN) && !skb_cloned(skb))
 361                 goto done;
 362
 363         skb2 = skb_copy_expand(skb, EEM_HLEN, ETH_FCS_LEN + padlen, GFP_ATOMIC);
 364         dev_kfree_skb_any(skb);
 365         skb = skb2;
 366         if (!skb)
 367                 return skb;
 368
 369 done:
 370         /* use the "no CRC" option */
 371         put_unaligned_be32(0xdeadbeef, skb_put(skb, 4));
 372
 373         /* EEM packet header format:
 374          * b0..13:      length of ethernet frame
 375          * b14:         bmCRC (0 == sentinel CRC)
 376          * b15:         bmType (0 == data)
 377          */
 378         len = skb->len;
 379         put_unaligned_le16(len & 0x3FFF, skb_push(skb, 2));
 380
 381         /* add a zero-length EEM packet, if needed */
 382         if (padlen)
 383                 put_unaligned_le16(0, skb_put(skb, 2));
 384
 385         return skb;
 386 }
 387
 388 /*
 389  * Remove the EEM header.  Note that there can be many EEM packets in a single
 390  * USB transfer, so we need to break them out and handle them independently.
 391  */
 392 static int eem_unwrap(struct gether *port,
 393                         struct sk_buff *skb,
 394                         struct sk_buff_head *list)
 395 {
 396         struct usb_composite_dev        *cdev = port->func.config->cdev;
 397         int                             status = 0;
 398
 399         do {
 400                 struct sk_buff  *skb2;
 401                 u16             header;
 402                 u16             len = 0;
 403
 404                 if (skb->len < EEM_HLEN) {
 405                         status = -EINVAL;
 406                         DBG(cdev, "invalid EEM header\n");
 407                         goto error;
 408                 }
 409
 410                 /* remove the EEM header */
 411                 header = get_unaligned_le16(skb->data);
 412                 skb_pull(skb, EEM_HLEN);
 413
 414                 /* EEM packet header format:
 415                  * b0..14:      EEM type dependent (data or command)
 416                  * b15:         bmType (0 == data, 1 == command)
 417                  */
 418                 if (header & BIT(15)) {
 419                         struct usb_request      *req;
 420                         struct in_context       *ctx;
 421                         struct usb_ep           *ep;
 422                         u16                     bmEEMCmd;
 423
 424                         /* EEM command packet format:
 425                          * b0..10:      bmEEMCmdParam
 426                          * b11..13:     bmEEMCmd
 427                          * b14:         reserved (must be zero)
 428                          * b15:         bmType (1 == command)
 429                          */
 430                         if (header & BIT(14))
 431                                 continue;
 432
 433                         bmEEMCmd = (header >> 11) & 0x7;
 434                         switch (bmEEMCmd) {
 435                         case 0: /* echo */
 436                                 len = header & 0x7FF;
 437                                 if (skb->len < len) {
 438                                         status = -EOVERFLOW;
 439                                         goto error;
 440                                 }
 441
 442                                 skb2 = skb_clone(skb, GFP_ATOMIC);
 443                                 if (unlikely(!skb2)) {
 444                                         DBG(cdev, "EEM echo response error\n");
 445                                         goto next;
 446                                 }
 447                                 skb_trim(skb2, len);
 448                                 put_unaligned_le16(BIT(15) | BIT(11) | len,
 449                                                         skb_push(skb2, 2));
 450
 451                                 ep = port->in_ep;
 452                                 req = usb_ep_alloc_request(ep, GFP_ATOMIC);
 453                                 if (!req) {
 454                                         dev_kfree_skb_any(skb2);
 455                                         goto next;
 456                                 }
 457
 458                                 req->buf = kmalloc(skb2->len, GFP_KERNEL);
 459                                 if (!req->buf) {
 460                                         usb_ep_free_request(ep, req);
 461                                         dev_kfree_skb_any(skb2);
 462                                         goto next;
 463                                 }
 464
 465                                 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
 466                                 if (!ctx) {
 467                                         kfree(req->buf);
 468                                         usb_ep_free_request(ep, req);
 469                                         dev_kfree_skb_any(skb2);
 470                                         goto next;
 471                                 }
 472                                 ctx->skb = skb2;
 473                                 ctx->ep = ep;
 474
 475                                 skb_copy_bits(skb2, 0, req->buf, skb2->len);
 476                                 req->length = skb2->len;
 477                                 req->complete = eem_cmd_complete;
 478                                 req->zero = 1;
 479                                 req->context = ctx;
 480                                 if (usb_ep_queue(port->in_ep, req, GFP_ATOMIC))
 481                                         DBG(cdev, "echo response queue fail\n");
 482                                 break;
 483
 484                         case 1:  /* echo response */
 485                         case 2:  /* suspend hint */
 486                         case 3:  /* response hint */
 487                         case 4:  /* response complete hint */
 488                         case 5:  /* tickle */
 489                         default: /* reserved */
 490                                 continue;
 491                         }
 492                 } else {
 493                         u32             crc, crc2;
 494                         struct sk_buff  *skb3;
 495
 496                         /* check for zero-length EEM packet */
 497                         if (header == 0)
 498                                 continue;
 499
 500                         /* EEM data packet format:
 501                          * b0..13:      length of ethernet frame
 502                          * b14:         bmCRC (0 == sentinel, 1 == calculated)
 503                          * b15:         bmType (0 == data)
 504                          */
 505                         len = header & 0x3FFF;
 506                         if ((skb->len < len)
 507                                         || (len < (ETH_HLEN + ETH_FCS_LEN))) {
 508                                 status = -EINVAL;
 509                                 goto error;
 510                         }
 511
 512                         /* validate CRC */
 513                         if (header & BIT(14)) {
 514                                 crc = get_unaligned_le32(skb->data + len
 515                                                         - ETH_FCS_LEN);
 516                                 crc2 = ~crc32_le(~0,
 517                                                 skb->data, len - ETH_FCS_LEN);
 518                         } else {
 519                                 crc = get_unaligned_be32(skb->data + len
 520                                                         - ETH_FCS_LEN);
 521                                 crc2 = 0xdeadbeef;
 522                         }
 523                         if (crc != crc2) {
 524                                 DBG(cdev, "invalid EEM CRC\n");
 525                                 goto next;
 526                         }
 527
 528                         skb2 = skb_clone(skb, GFP_ATOMIC);
 529                         if (unlikely(!skb2)) {
 530                                 DBG(cdev, "unable to unframe EEM packet\n");
 531                                 goto next;
 532                         }
 533                         skb_trim(skb2, len - ETH_FCS_LEN);
 534
 535                         skb3 = skb_copy_expand(skb2,
 536                                                 NET_IP_ALIGN,
 537                                                 0,
 538                                                 GFP_ATOMIC);
 539                         if (unlikely(!skb3)) {
 540                                 dev_kfree_skb_any(skb2);
 541                                 goto next;
 542                         }
 543                         dev_kfree_skb_any(skb2);
 544                         skb_queue_tail(list, skb3);
 545                 }
 546 next:
 547                 skb_pull(skb, len);
 548         } while (skb->len);
 549
 550 error:
 551         dev_kfree_skb_any(skb);
 552         return status;
 553 }
 554
 555 static inline struct f_eem_opts *to_f_eem_opts(struct config_item *item)
 556 {
 557         return container_of(to_config_group(item), struct f_eem_opts,
 558                             func_inst.group);
 559 }
 560
 561 /* f_eem_item_ops */
 562 USB_ETHERNET_CONFIGFS_ITEM(eem);
 563
 564 /* f_eem_opts_dev_addr */
 565 USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(eem);
 566
 567 /* f_eem_opts_host_addr */
 568 USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(eem);
 569
 570 /* f_eem_opts_qmult */
 571 USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(eem);
 572
 573 /* f_eem_opts_ifname */
 574 USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(eem);
 575
 576 static struct configfs_attribute *eem_attrs[] = {
 577         &eem_opts_attr_dev_addr,
 578         &eem_opts_attr_host_addr,
 579         &eem_opts_attr_qmult,
 580         &eem_opts_attr_ifname,
 581         NULL,
 582 };
 583
 584 static const struct config_item_type eem_func_type = {
 585         .ct_item_ops    = &eem_item_ops,
 586         .ct_attrs       = eem_attrs,
 587         .ct_owner       = THIS_MODULE,
 588 };
 589
 590 static void eem_free_inst(struct usb_function_instance *f)
 591 {
 592         struct f_eem_opts *opts;
 593
 594         opts = container_of(f, struct f_eem_opts, func_inst);
 595         if (opts->bound)
 596                 gether_cleanup(netdev_priv(opts->net));
 597         else
 598                 free_netdev(opts->net);
 599         kfree(opts);
 600 }
 601
 602 static struct usb_function_instance *eem_alloc_inst(void)
 603 {
 604         struct f_eem_opts *opts;
 605
 606         opts = kzalloc(sizeof(*opts), GFP_KERNEL);
 607         if (!opts)
 608                 return ERR_PTR(-ENOMEM);
 609         mutex_init(&opts->lock);
 610         opts->func_inst.free_func_inst = eem_free_inst;
 611         opts->net = gether_setup_default();
 612         if (IS_ERR(opts->net)) {
 613                 struct net_device *net = opts->net;
 614                 kfree(opts);
 615                 return ERR_CAST(net);
 616         }
 617
 618         config_group_init_type_name(&opts->func_inst.group, "", &eem_func_type);
 619
 620         return &opts->func_inst;
 621 }
 622
 623 static void eem_free(struct usb_function *f)
 624 {
 625         struct f_eem *eem;
 626         struct f_eem_opts *opts;
 627
 628         eem = func_to_eem(f);
 629         opts = container_of(f->fi, struct f_eem_opts, func_inst);
 630         kfree(eem);
 631         mutex_lock(&opts->lock);
 632         opts->refcnt--;
 633         mutex_unlock(&opts->lock);
 634 }
 635
 636 static void eem_unbind(struct usb_configuration *c, struct usb_function *f)
 637 {
 638         DBG(c->cdev, "eem unbind\n");
 639
 640         usb_free_all_descriptors(f);
 641 }
 642
 643 static struct usb_function *eem_alloc(struct usb_function_instance *fi)
 644 {
 645         struct f_eem    *eem;
 646         struct f_eem_opts *opts;
 647
 648         /* allocate and initialize one new instance */
 649         eem = kzalloc(sizeof(*eem), GFP_KERNEL);
 650         if (!eem)
 651                 return ERR_PTR(-ENOMEM);
 652
 653         opts = container_of(fi, struct f_eem_opts, func_inst);
 654         mutex_lock(&opts->lock);
 655         opts->refcnt++;
 656
 657         eem->port.ioport = netdev_priv(opts->net);
 658         mutex_unlock(&opts->lock);
 659         eem->port.cdc_filter = DEFAULT_FILTER;
 660
 661         eem->port.func.name = "cdc_eem";
 662         /* descriptors are per-instance copies */
 663         eem->port.func.bind = eem_bind;
 664         eem->port.func.unbind = eem_unbind;
 665         eem->port.func.set_alt = eem_set_alt;
 666         eem->port.func.setup = eem_setup;
 667         eem->port.func.disable = eem_disable;
 668         eem->port.func.free_func = eem_free;
 669         eem->port.wrap = eem_wrap;
 670         eem->port.unwrap = eem_unwrap;
 671         eem->port.header_len = EEM_HLEN;
 672
 673         return &eem->port.func;
 674 }
 675
 676 DECLARE_USB_FUNCTION_INIT(eem, eem_alloc_inst, eem_alloc);
 677 MODULE_DESCRIPTION("USB CDC Ethernet (EEM) link function driver");
 678 MODULE_LICENSE("GPL");
 679 MODULE_AUTHOR("David Brownell");