drivers/usb/gadget/function/f_subset.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * f_subset.c -- "CDC Subset" Ethernet link function driver
   4  *
   5  * Copyright (C) 2003-2005,2008 David Brownell
   6  * Copyright (C) 2008 Nokia Corporation
   7  */
   8
   9 #include <linux/slab.h>
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/device.h>
  13 #include <linux/etherdevice.h>
  14
  15 #include "u_ether.h"
  16 #include "u_ether_configfs.h"
  17 #include "u_gether.h"
  18
  19 /*
  20  * This function packages a simple "CDC Subset" Ethernet port with no real
  21  * control mechanisms; just raw data transfer over two bulk endpoints.
  22  * The data transfer model is exactly that of CDC Ethernet, which is
  23  * why we call it the "CDC Subset".
  24  *
  25  * Because it's not standardized, this has some interoperability issues.
  26  * They mostly relate to driver binding, since the data transfer model is
  27  * so simple (CDC Ethernet).  The original versions of this protocol used
  28  * specific product/vendor IDs:  byteswapped IDs for Digital Equipment's
  29  * SA-1100 "Itsy" board, which could run Linux 2.4 kernels and supported
  30  * daughtercards with USB peripheral connectors.  (It was used more often
  31  * with other boards, using the Itsy identifiers.)  Linux hosts recognized
  32  * this with CONFIG_USB_ARMLINUX; these devices have only one configuration
  33  * and one interface.
  34  *
  35  * At some point, MCCI defined a (nonconformant) CDC MDLM variant called
  36  * "SAFE", which happens to have a mode which is identical to the "CDC
  37  * Subset" in terms of data transfer and lack of control model.  This was
  38  * adopted by later Sharp Zaurus models, and by some other software which
  39  * Linux hosts recognize with CONFIG_USB_NET_ZAURUS.
  40  *
  41  * Because Microsoft's RNDIS drivers are far from robust, we added a few
  42  * descriptors to the CDC Subset code, making this code look like a SAFE
  43  * implementation.  This lets you use MCCI's host side MS-Windows drivers
  44  * if you get fed up with RNDIS.  It also makes it easier for composite
  45  * drivers to work, since they can use class based binding instead of
  46  * caring about specific product and vendor IDs.
  47  */
  48
  49 struct f_gether {
  50         struct gether                   port;
  51
  52         char                            ethaddr[14];
  53 };
  54
  55 static inline struct f_gether *func_to_geth(struct usb_function *f)
  56 {
  57         return container_of(f, struct f_gether, port.func);
  58 }
  59
  60 /*-------------------------------------------------------------------------*/
  61
  62 /*
  63  * "Simple" CDC-subset option is a simple vendor-neutral model that most
  64  * full speed controllers can handle:  one interface, two bulk endpoints.
  65  * To assist host side drivers, we fancy it up a bit, and add descriptors so
  66  * some host side drivers will understand it as a "SAFE" variant.
  67  *
  68  * "SAFE" loosely follows CDC WMC MDLM, violating the spec in various ways.
  69  * Data endpoints live in the control interface, there's no data interface.
  70  * And it's not used to talk to a cell phone radio.
  71  */
  72
  73 /* interface descriptor: */
  74
  75 static struct usb_interface_descriptor subset_data_intf = {
  76         .bLength =              sizeof subset_data_intf,
  77         .bDescriptorType =      USB_DT_INTERFACE,
  78
  79         /* .bInterfaceNumber = DYNAMIC */
  80         .bAlternateSetting =    0,
  81         .bNumEndpoints =        2,
  82         .bInterfaceClass =      USB_CLASS_COMM,
  83         .bInterfaceSubClass =   USB_CDC_SUBCLASS_MDLM,
  84         .bInterfaceProtocol =   0,
  85         /* .iInterface = DYNAMIC */
  86 };
  87
  88 static struct usb_cdc_header_desc mdlm_header_desc = {
  89         .bLength =              sizeof mdlm_header_desc,
  90         .bDescriptorType =      USB_DT_CS_INTERFACE,
  91         .bDescriptorSubType =   USB_CDC_HEADER_TYPE,
  92
  93         .bcdCDC =               cpu_to_le16(0x0110),
  94 };
  95
  96 static struct usb_cdc_mdlm_desc mdlm_desc = {
  97         .bLength =              sizeof mdlm_desc,
  98         .bDescriptorType =      USB_DT_CS_INTERFACE,
  99         .bDescriptorSubType =   USB_CDC_MDLM_TYPE,
 100
 101         .bcdVersion =           cpu_to_le16(0x0100),
 102         .bGUID = {
 103                 0x5d, 0x34, 0xcf, 0x66, 0x11, 0x18, 0x11, 0xd6,
 104                 0xa2, 0x1a, 0x00, 0x01, 0x02, 0xca, 0x9a, 0x7f,
 105         },
 106 };
 107
 108 /* since "usb_cdc_mdlm_detail_desc" is a variable length structure, we
 109  * can't really use its struct.  All we do here is say that we're using
 110  * the submode of "SAFE" which directly matches the CDC Subset.
 111  */
 112 static u8 mdlm_detail_desc[] = {
 113         6,
 114         USB_DT_CS_INTERFACE,
 115         USB_CDC_MDLM_DETAIL_TYPE,
 116
 117         0,      /* "SAFE" */
 118         0,      /* network control capabilities (none) */
 119         0,      /* network data capabilities ("raw" encapsulation) */
 120 };
 121
 122 static struct usb_cdc_ether_desc ether_desc = {
 123         .bLength =              sizeof ether_desc,
 124         .bDescriptorType =      USB_DT_CS_INTERFACE,
 125         .bDescriptorSubType =   USB_CDC_ETHERNET_TYPE,
 126
 127         /* this descriptor actually adds value, surprise! */
 128         /* .iMACAddress = DYNAMIC */
 129         .bmEthernetStatistics = cpu_to_le32(0), /* no statistics */
 130         .wMaxSegmentSize =      cpu_to_le16(ETH_FRAME_LEN),
 131         .wNumberMCFilters =     cpu_to_le16(0),
 132         .bNumberPowerFilters =  0,
 133 };
 134
 135 /* full speed support: */
 136
 137 static struct usb_endpoint_descriptor fs_subset_in_desc = {
 138         .bLength =              USB_DT_ENDPOINT_SIZE,
 139         .bDescriptorType =      USB_DT_ENDPOINT,
 140
 141         .bEndpointAddress =     USB_DIR_IN,
 142         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 143 };
 144
 145 static struct usb_endpoint_descriptor fs_subset_out_desc = {
 146         .bLength =              USB_DT_ENDPOINT_SIZE,
 147         .bDescriptorType =      USB_DT_ENDPOINT,
 148
 149         .bEndpointAddress =     USB_DIR_OUT,
 150         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 151 };
 152
 153 static struct usb_descriptor_header *fs_eth_function[] = {
 154         (struct usb_descriptor_header *) &subset_data_intf,
 155         (struct usb_descriptor_header *) &mdlm_header_desc,
 156         (struct usb_descriptor_header *) &mdlm_desc,
 157         (struct usb_descriptor_header *) &mdlm_detail_desc,
 158         (struct usb_descriptor_header *) &ether_desc,
 159         (struct usb_descriptor_header *) &fs_subset_in_desc,
 160         (struct usb_descriptor_header *) &fs_subset_out_desc,
 161         NULL,
 162 };
 163
 164 /* high speed support: */
 165
 166 static struct usb_endpoint_descriptor hs_subset_in_desc = {
 167         .bLength =              USB_DT_ENDPOINT_SIZE,
 168         .bDescriptorType =      USB_DT_ENDPOINT,
 169
 170         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 171         .wMaxPacketSize =       cpu_to_le16(512),
 172 };
 173
 174 static struct usb_endpoint_descriptor hs_subset_out_desc = {
 175         .bLength =              USB_DT_ENDPOINT_SIZE,
 176         .bDescriptorType =      USB_DT_ENDPOINT,
 177
 178         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 179         .wMaxPacketSize =       cpu_to_le16(512),
 180 };
 181
 182 static struct usb_descriptor_header *hs_eth_function[] = {
 183         (struct usb_descriptor_header *) &subset_data_intf,
 184         (struct usb_descriptor_header *) &mdlm_header_desc,
 185         (struct usb_descriptor_header *) &mdlm_desc,
 186         (struct usb_descriptor_header *) &mdlm_detail_desc,
 187         (struct usb_descriptor_header *) &ether_desc,
 188         (struct usb_descriptor_header *) &hs_subset_in_desc,
 189         (struct usb_descriptor_header *) &hs_subset_out_desc,
 190         NULL,
 191 };
 192
 193 /* super speed support: */
 194
 195 static struct usb_endpoint_descriptor ss_subset_in_desc = {
 196         .bLength =              USB_DT_ENDPOINT_SIZE,
 197         .bDescriptorType =      USB_DT_ENDPOINT,
 198
 199         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 200         .wMaxPacketSize =       cpu_to_le16(1024),
 201 };
 202
 203 static struct usb_endpoint_descriptor ss_subset_out_desc = {
 204         .bLength =              USB_DT_ENDPOINT_SIZE,
 205         .bDescriptorType =      USB_DT_ENDPOINT,
 206
 207         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 208         .wMaxPacketSize =       cpu_to_le16(1024),
 209 };
 210
 211 static struct usb_ss_ep_comp_descriptor ss_subset_bulk_comp_desc = {
 212         .bLength =              sizeof ss_subset_bulk_comp_desc,
 213         .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
 214
 215         /* the following 2 values can be tweaked if necessary */
 216         /* .bMaxBurst =         0, */
 217         /* .bmAttributes =      0, */
 218 };
 219
 220 static struct usb_descriptor_header *ss_eth_function[] = {
 221         (struct usb_descriptor_header *) &subset_data_intf,
 222         (struct usb_descriptor_header *) &mdlm_header_desc,
 223         (struct usb_descriptor_header *) &mdlm_desc,
 224         (struct usb_descriptor_header *) &mdlm_detail_desc,
 225         (struct usb_descriptor_header *) &ether_desc,
 226         (struct usb_descriptor_header *) &ss_subset_in_desc,
 227         (struct usb_descriptor_header *) &ss_subset_bulk_comp_desc,
 228         (struct usb_descriptor_header *) &ss_subset_out_desc,
 229         (struct usb_descriptor_header *) &ss_subset_bulk_comp_desc,
 230         NULL,
 231 };
 232
 233 /* string descriptors: */
 234
 235 static struct usb_string geth_string_defs[] = {
 236         [0].s = "CDC Ethernet Subset/SAFE",
 237         [1].s = "",
 238         {  } /* end of list */
 239 };
 240
 241 static struct usb_gadget_strings geth_string_table = {
 242         .language =             0x0409, /* en-us */
 243         .strings =              geth_string_defs,
 244 };
 245
 246 static struct usb_gadget_strings *geth_strings[] = {
 247         &geth_string_table,
 248         NULL,
 249 };
 250
 251 /*-------------------------------------------------------------------------*/
 252
 253 static int geth_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 254 {
 255         struct f_gether         *geth = func_to_geth(f);
 256         struct usb_composite_dev *cdev = f->config->cdev;
 257         struct net_device       *net;
 258
 259         /* we know alt == 0, so this is an activation or a reset */
 260
 261         if (geth->port.in_ep->enabled) {
 262                 DBG(cdev, "reset cdc subset\n");
 263                 gether_disconnect(&geth->port);
 264         }
 265
 266         DBG(cdev, "init + activate cdc subset\n");
 267         if (config_ep_by_speed(cdev->gadget, f, geth->port.in_ep) ||
 268             config_ep_by_speed(cdev->gadget, f, geth->port.out_ep)) {
 269                 geth->port.in_ep->desc = NULL;
 270                 geth->port.out_ep->desc = NULL;
 271                 return -EINVAL;
 272         }
 273
 274         net = gether_connect(&geth->port);
 275         return PTR_ERR_OR_ZERO(net);
 276 }
 277
 278 static void geth_disable(struct usb_function *f)
 279 {
 280         struct f_gether *geth = func_to_geth(f);
 281         struct usb_composite_dev *cdev = f->config->cdev;
 282
 283         DBG(cdev, "net deactivated\n");
 284         gether_disconnect(&geth->port);
 285 }
 286
 287 /*-------------------------------------------------------------------------*/
 288
 289 /* serial function driver setup/binding */
 290
 291 static int
 292 geth_bind(struct usb_configuration *c, struct usb_function *f)
 293 {
 294         struct usb_composite_dev *cdev = c->cdev;
 295         struct f_gether         *geth = func_to_geth(f);
 296         struct usb_string       *us;
 297         int                     status;
 298         struct usb_ep           *ep;
 299
 300         struct f_gether_opts    *gether_opts;
 301
 302         gether_opts = container_of(f->fi, struct f_gether_opts, func_inst);
 303
 304         /*
 305          * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
 306          * configurations are bound in sequence with list_for_each_entry,
 307          * in each configuration its functions are bound in sequence
 308          * with list_for_each_entry, so we assume no race condition
 309          * with regard to gether_opts->bound access
 310          */
 311         if (!gether_opts->bound) {
 312                 mutex_lock(&gether_opts->lock);
 313                 gether_set_gadget(gether_opts->net, cdev->gadget);
 314                 status = gether_register_netdev(gether_opts->net);
 315                 mutex_unlock(&gether_opts->lock);
 316                 if (status)
 317                         return status;
 318                 gether_opts->bound = true;
 319         }
 320
 321         us = usb_gstrings_attach(cdev, geth_strings,
 322                                  ARRAY_SIZE(geth_string_defs));
 323         if (IS_ERR(us))
 324                 return PTR_ERR(us);
 325
 326         subset_data_intf.iInterface = us[0].id;
 327         ether_desc.iMACAddress = us[1].id;
 328
 329         /* allocate instance-specific interface IDs */
 330         status = usb_interface_id(c, f);
 331         if (status < 0)
 332                 goto fail;
 333         subset_data_intf.bInterfaceNumber = status;
 334
 335         status = -ENODEV;
 336
 337         /* allocate instance-specific endpoints */
 338         ep = usb_ep_autoconfig(cdev->gadget, &fs_subset_in_desc);
 339         if (!ep)
 340                 goto fail;
 341         geth->port.in_ep = ep;
 342
 343         ep = usb_ep_autoconfig(cdev->gadget, &fs_subset_out_desc);
 344         if (!ep)
 345                 goto fail;
 346         geth->port.out_ep = ep;
 347
 348         /* support all relevant hardware speeds... we expect that when
 349          * hardware is dual speed, all bulk-capable endpoints work at
 350          * both speeds
 351          */
 352         hs_subset_in_desc.bEndpointAddress = fs_subset_in_desc.bEndpointAddress;
 353         hs_subset_out_desc.bEndpointAddress =
 354                 fs_subset_out_desc.bEndpointAddress;
 355
 356         ss_subset_in_desc.bEndpointAddress = fs_subset_in_desc.bEndpointAddress;
 357         ss_subset_out_desc.bEndpointAddress =
 358                 fs_subset_out_desc.bEndpointAddress;
 359
 360         status = usb_assign_descriptors(f, fs_eth_function, hs_eth_function,
 361                         ss_eth_function, NULL);
 362         if (status)
 363                 goto fail;
 364
 365         /* NOTE:  all that is done without knowing or caring about
 366          * the network link ... which is unavailable to this code
 367          * until we're activated via set_alt().
 368          */
 369
 370         DBG(cdev, "CDC Subset: %s speed IN/%s OUT/%s\n",
 371                         gadget_is_superspeed(c->cdev->gadget) ? "super" :
 372                         gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
 373                         geth->port.in_ep->name, geth->port.out_ep->name);
 374         return 0;
 375
 376 fail:
 377         ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
 378
 379         return status;
 380 }
 381
 382 static inline struct f_gether_opts *to_f_gether_opts(struct config_item *item)
 383 {
 384         return container_of(to_config_group(item), struct f_gether_opts,
 385                             func_inst.group);
 386 }
 387
 388 /* f_gether_item_ops */
 389 USB_ETHERNET_CONFIGFS_ITEM(gether);
 390
 391 /* f_gether_opts_dev_addr */
 392 USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(gether);
 393
 394 /* f_gether_opts_host_addr */
 395 USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(gether);
 396
 397 /* f_gether_opts_qmult */
 398 USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(gether);
 399
 400 /* f_gether_opts_ifname */
 401 USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(gether);
 402
 403 static struct configfs_attribute *gether_attrs[] = {
 404         &gether_opts_attr_dev_addr,
 405         &gether_opts_attr_host_addr,
 406         &gether_opts_attr_qmult,
 407         &gether_opts_attr_ifname,
 408         NULL,
 409 };
 410
 411 static const struct config_item_type gether_func_type = {
 412         .ct_item_ops    = &gether_item_ops,
 413         .ct_attrs       = gether_attrs,
 414         .ct_owner       = THIS_MODULE,
 415 };
 416
 417 static void geth_free_inst(struct usb_function_instance *f)
 418 {
 419         struct f_gether_opts *opts;
 420
 421         opts = container_of(f, struct f_gether_opts, func_inst);
 422         if (opts->bound)
 423                 gether_cleanup(netdev_priv(opts->net));
 424         else
 425                 free_netdev(opts->net);
 426         kfree(opts);
 427 }
 428
 429 static struct usb_function_instance *geth_alloc_inst(void)
 430 {
 431         struct f_gether_opts *opts;
 432
 433         opts = kzalloc(sizeof(*opts), GFP_KERNEL);
 434         if (!opts)
 435                 return ERR_PTR(-ENOMEM);
 436         mutex_init(&opts->lock);
 437         opts->func_inst.free_func_inst = geth_free_inst;
 438         opts->net = gether_setup_default();
 439         if (IS_ERR(opts->net)) {
 440                 struct net_device *net = opts->net;
 441                 kfree(opts);
 442                 return ERR_CAST(net);
 443         }
 444
 445         config_group_init_type_name(&opts->func_inst.group, "",
 446                                     &gether_func_type);
 447
 448         return &opts->func_inst;
 449 }
 450
 451 static void geth_free(struct usb_function *f)
 452 {
 453         struct f_gether *eth;
 454
 455         eth = func_to_geth(f);
 456         kfree(eth);
 457 }
 458
 459 static void geth_unbind(struct usb_configuration *c, struct usb_function *f)
 460 {
 461         geth_string_defs[0].id = 0;
 462         usb_free_all_descriptors(f);
 463 }
 464
 465 static struct usb_function *geth_alloc(struct usb_function_instance *fi)
 466 {
 467         struct f_gether *geth;
 468         struct f_gether_opts *opts;
 469         int status;
 470
 471         /* allocate and initialize one new instance */
 472         geth = kzalloc(sizeof(*geth), GFP_KERNEL);
 473         if (!geth)
 474                 return ERR_PTR(-ENOMEM);
 475
 476         opts = container_of(fi, struct f_gether_opts, func_inst);
 477
 478         mutex_lock(&opts->lock);
 479         opts->refcnt++;
 480         /* export host's Ethernet address in CDC format */
 481         status = gether_get_host_addr_cdc(opts->net, geth->ethaddr,
 482                                           sizeof(geth->ethaddr));
 483         if (status < 12) {
 484                 kfree(geth);
 485                 mutex_unlock(&opts->lock);
 486                 return ERR_PTR(-EINVAL);
 487         }
 488         geth_string_defs[1].s = geth->ethaddr;
 489
 490         geth->port.ioport = netdev_priv(opts->net);
 491         mutex_unlock(&opts->lock);
 492         geth->port.cdc_filter = DEFAULT_FILTER;
 493
 494         geth->port.func.name = "cdc_subset";
 495         geth->port.func.bind = geth_bind;
 496         geth->port.func.unbind = geth_unbind;
 497         geth->port.func.set_alt = geth_set_alt;
 498         geth->port.func.disable = geth_disable;
 499         geth->port.func.free_func = geth_free;
 500
 501         return &geth->port.func;
 502 }
 503
 504 DECLARE_USB_FUNCTION_INIT(geth, geth_alloc_inst, geth_alloc);
 505 MODULE_LICENSE("GPL");
 506 MODULE_AUTHOR("David Brownell");