drivers/usb/gadget/function/f_loopback.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * f_loopback.c - USB peripheral loopback configuration driver
   4  *
   5  * Copyright (C) 2003-2008 David Brownell
   6  * Copyright (C) 2008 by Nokia Corporation
   7  */
   8
   9 /* #define VERBOSE_DEBUG */
  10
  11 #include <linux/slab.h>
  12 #include <linux/kernel.h>
  13 #include <linux/device.h>
  14 #include <linux/module.h>
  15 #include <linux/err.h>
  16 #include <linux/usb/composite.h>
  17
  18 #include "g_zero.h"
  19 #include "u_f.h"
  20
  21 /*
  22  * LOOPBACK FUNCTION ... a testing vehicle for USB peripherals,
  23  *
  24  * This takes messages of various sizes written OUT to a device, and loops
  25  * them back so they can be read IN from it.  It has been used by certain
  26  * test applications.  It supports limited testing of data queueing logic.
  27  */
  28 struct f_loopback {
  29         struct usb_function     function;
  30
  31         struct usb_ep           *in_ep;
  32         struct usb_ep           *out_ep;
  33
  34         unsigned                qlen;
  35         unsigned                buflen;
  36 };
  37
  38 static inline struct f_loopback *func_to_loop(struct usb_function *f)
  39 {
  40         return container_of(f, struct f_loopback, function);
  41 }
  42
  43 /*-------------------------------------------------------------------------*/
  44
  45 static struct usb_interface_descriptor loopback_intf = {
  46         .bLength =              sizeof(loopback_intf),
  47         .bDescriptorType =      USB_DT_INTERFACE,
  48
  49         .bNumEndpoints =        2,
  50         .bInterfaceClass =      USB_CLASS_VENDOR_SPEC,
  51         /* .iInterface = DYNAMIC */
  52 };
  53
  54 /* full speed support: */
  55
  56 static struct usb_endpoint_descriptor fs_loop_source_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 fs_loop_sink_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 *fs_loopback_descs[] = {
  73         (struct usb_descriptor_header *) &loopback_intf,
  74         (struct usb_descriptor_header *) &fs_loop_sink_desc,
  75         (struct usb_descriptor_header *) &fs_loop_source_desc,
  76         NULL,
  77 };
  78
  79 /* high speed support: */
  80
  81 static struct usb_endpoint_descriptor hs_loop_source_desc = {
  82         .bLength =              USB_DT_ENDPOINT_SIZE,
  83         .bDescriptorType =      USB_DT_ENDPOINT,
  84
  85         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  86         .wMaxPacketSize =       cpu_to_le16(512),
  87 };
  88
  89 static struct usb_endpoint_descriptor hs_loop_sink_desc = {
  90         .bLength =              USB_DT_ENDPOINT_SIZE,
  91         .bDescriptorType =      USB_DT_ENDPOINT,
  92
  93         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  94         .wMaxPacketSize =       cpu_to_le16(512),
  95 };
  96
  97 static struct usb_descriptor_header *hs_loopback_descs[] = {
  98         (struct usb_descriptor_header *) &loopback_intf,
  99         (struct usb_descriptor_header *) &hs_loop_source_desc,
 100         (struct usb_descriptor_header *) &hs_loop_sink_desc,
 101         NULL,
 102 };
 103
 104 /* super speed support: */
 105
 106 static struct usb_endpoint_descriptor ss_loop_source_desc = {
 107         .bLength =              USB_DT_ENDPOINT_SIZE,
 108         .bDescriptorType =      USB_DT_ENDPOINT,
 109
 110         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 111         .wMaxPacketSize =       cpu_to_le16(1024),
 112 };
 113
 114 static struct usb_ss_ep_comp_descriptor ss_loop_source_comp_desc = {
 115         .bLength =              USB_DT_SS_EP_COMP_SIZE,
 116         .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
 117         .bMaxBurst =            0,
 118         .bmAttributes =         0,
 119         .wBytesPerInterval =    0,
 120 };
 121
 122 static struct usb_endpoint_descriptor ss_loop_sink_desc = {
 123         .bLength =              USB_DT_ENDPOINT_SIZE,
 124         .bDescriptorType =      USB_DT_ENDPOINT,
 125
 126         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 127         .wMaxPacketSize =       cpu_to_le16(1024),
 128 };
 129
 130 static struct usb_ss_ep_comp_descriptor ss_loop_sink_comp_desc = {
 131         .bLength =              USB_DT_SS_EP_COMP_SIZE,
 132         .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
 133         .bMaxBurst =            0,
 134         .bmAttributes =         0,
 135         .wBytesPerInterval =    0,
 136 };
 137
 138 static struct usb_descriptor_header *ss_loopback_descs[] = {
 139         (struct usb_descriptor_header *) &loopback_intf,
 140         (struct usb_descriptor_header *) &ss_loop_source_desc,
 141         (struct usb_descriptor_header *) &ss_loop_source_comp_desc,
 142         (struct usb_descriptor_header *) &ss_loop_sink_desc,
 143         (struct usb_descriptor_header *) &ss_loop_sink_comp_desc,
 144         NULL,
 145 };
 146
 147 /* function-specific strings: */
 148
 149 static struct usb_string strings_loopback[] = {
 150         [0].s = "loop input to output",
 151         {  }                    /* end of list */
 152 };
 153
 154 static struct usb_gadget_strings stringtab_loop = {
 155         .language       = 0x0409,       /* en-us */
 156         .strings        = strings_loopback,
 157 };
 158
 159 static struct usb_gadget_strings *loopback_strings[] = {
 160         &stringtab_loop,
 161         NULL,
 162 };
 163
 164 /*-------------------------------------------------------------------------*/
 165
 166 static int loopback_bind(struct usb_configuration *c, struct usb_function *f)
 167 {
 168         struct usb_composite_dev *cdev = c->cdev;
 169         struct f_loopback       *loop = func_to_loop(f);
 170         int                     id;
 171         int ret;
 172
 173         /* allocate interface ID(s) */
 174         id = usb_interface_id(c, f);
 175         if (id < 0)
 176                 return id;
 177         loopback_intf.bInterfaceNumber = id;
 178
 179         id = usb_string_id(cdev);
 180         if (id < 0)
 181                 return id;
 182         strings_loopback[0].id = id;
 183         loopback_intf.iInterface = id;
 184
 185         /* allocate endpoints */
 186
 187         loop->in_ep = usb_ep_autoconfig(cdev->gadget, &fs_loop_source_desc);
 188         if (!loop->in_ep) {
 189 autoconf_fail:
 190                 ERROR(cdev, "%s: can't autoconfigure on %s\n",
 191                         f->name, cdev->gadget->name);
 192                 return -ENODEV;
 193         }
 194
 195         loop->out_ep = usb_ep_autoconfig(cdev->gadget, &fs_loop_sink_desc);
 196         if (!loop->out_ep)
 197                 goto autoconf_fail;
 198
 199         /* support high speed hardware */
 200         hs_loop_source_desc.bEndpointAddress =
 201                 fs_loop_source_desc.bEndpointAddress;
 202         hs_loop_sink_desc.bEndpointAddress = fs_loop_sink_desc.bEndpointAddress;
 203
 204         /* support super speed hardware */
 205         ss_loop_source_desc.bEndpointAddress =
 206                 fs_loop_source_desc.bEndpointAddress;
 207         ss_loop_sink_desc.bEndpointAddress = fs_loop_sink_desc.bEndpointAddress;
 208
 209         ret = usb_assign_descriptors(f, fs_loopback_descs, hs_loopback_descs,
 210                         ss_loopback_descs, ss_loopback_descs);
 211         if (ret)
 212                 return ret;
 213
 214         DBG(cdev, "%s: IN/%s, OUT/%s\n",
 215                         f->name, loop->in_ep->name, loop->out_ep->name);
 216         return 0;
 217 }
 218
 219 static void lb_free_func(struct usb_function *f)
 220 {
 221         struct f_lb_opts *opts;
 222
 223         opts = container_of(f->fi, struct f_lb_opts, func_inst);
 224
 225         mutex_lock(&opts->lock);
 226         opts->refcnt--;
 227         mutex_unlock(&opts->lock);
 228
 229         usb_free_all_descriptors(f);
 230         kfree(func_to_loop(f));
 231 }
 232
 233 static void loopback_complete(struct usb_ep *ep, struct usb_request *req)
 234 {
 235         struct f_loopback       *loop = ep->driver_data;
 236         struct usb_composite_dev *cdev = loop->function.config->cdev;
 237         int                     status = req->status;
 238
 239         switch (status) {
 240         case 0:                         /* normal completion? */
 241                 if (ep == loop->out_ep) {
 242                         /*
 243                          * We received some data from the host so let's
 244                          * queue it so host can read the from our in ep
 245                          */
 246                         struct usb_request *in_req = req->context;
 247
 248                         in_req->zero = (req->actual < req->length);
 249                         in_req->length = req->actual;
 250                         ep = loop->in_ep;
 251                         req = in_req;
 252                 } else {
 253                         /*
 254                          * We have just looped back a bunch of data
 255                          * to host. Now let's wait for some more data.
 256                          */
 257                         req = req->context;
 258                         ep = loop->out_ep;
 259                 }
 260
 261                 /* queue the buffer back to host or for next bunch of data */
 262                 status = usb_ep_queue(ep, req, GFP_ATOMIC);
 263                 if (status == 0) {
 264                         return;
 265                 } else {
 266                         ERROR(cdev, "Unable to loop back buffer to %s: %d\n",
 267                               ep->name, status);
 268                         goto free_req;
 269                 }
 270
 271                 /* "should never get here" */
 272         default:
 273                 ERROR(cdev, "%s loop complete --> %d, %d/%d\n", ep->name,
 274                                 status, req->actual, req->length);
 275                 fallthrough;
 276
 277         /* NOTE:  since this driver doesn't maintain an explicit record
 278          * of requests it submitted (just maintains qlen count), we
 279          * rely on the hardware driver to clean up on disconnect or
 280          * endpoint disable.
 281          */
 282         case -ECONNABORTED:             /* hardware forced ep reset */
 283         case -ECONNRESET:               /* request dequeued */
 284         case -ESHUTDOWN:                /* disconnect from host */
 285 free_req:
 286                 usb_ep_free_request(ep == loop->in_ep ?
 287                                     loop->out_ep : loop->in_ep,
 288                                     req->context);
 289                 free_ep_req(ep, req);
 290                 return;
 291         }
 292 }
 293
 294 static void disable_loopback(struct f_loopback *loop)
 295 {
 296         struct usb_composite_dev        *cdev;
 297
 298         cdev = loop->function.config->cdev;
 299         disable_endpoints(cdev, loop->in_ep, loop->out_ep, NULL, NULL);
 300         VDBG(cdev, "%s disabled\n", loop->function.name);
 301 }
 302
 303 static inline struct usb_request *lb_alloc_ep_req(struct usb_ep *ep, int len)
 304 {
 305         return alloc_ep_req(ep, len);
 306 }
 307
 308 static int alloc_requests(struct usb_composite_dev *cdev,
 309                           struct f_loopback *loop)
 310 {
 311         struct usb_request *in_req, *out_req;
 312         int i;
 313         int result = 0;
 314
 315         /*
 316          * allocate a bunch of read buffers and queue them all at once.
 317          * we buffer at most 'qlen' transfers; We allocate buffers only
 318          * for out transfer and reuse them in IN transfers to implement
 319          * our loopback functionality
 320          */
 321         for (i = 0; i < loop->qlen && result == 0; i++) {
 322                 result = -ENOMEM;
 323
 324                 in_req = usb_ep_alloc_request(loop->in_ep, GFP_ATOMIC);
 325                 if (!in_req)
 326                         goto fail;
 327
 328                 out_req = lb_alloc_ep_req(loop->out_ep, loop->buflen);
 329                 if (!out_req)
 330                         goto fail_in;
 331
 332                 in_req->complete = loopback_complete;
 333                 out_req->complete = loopback_complete;
 334
 335                 in_req->buf = out_req->buf;
 336                 /* length will be set in complete routine */
 337                 in_req->context = out_req;
 338                 out_req->context = in_req;
 339
 340                 result = usb_ep_queue(loop->out_ep, out_req, GFP_ATOMIC);
 341                 if (result) {
 342                         ERROR(cdev, "%s queue req --> %d\n",
 343                                         loop->out_ep->name, result);
 344                         goto fail_out;
 345                 }
 346         }
 347
 348         return 0;
 349
 350 fail_out:
 351         free_ep_req(loop->out_ep, out_req);
 352 fail_in:
 353         usb_ep_free_request(loop->in_ep, in_req);
 354 fail:
 355         return result;
 356 }
 357
 358 static int enable_endpoint(struct usb_composite_dev *cdev,
 359                            struct f_loopback *loop, struct usb_ep *ep)
 360 {
 361         int                                     result;
 362
 363         result = config_ep_by_speed(cdev->gadget, &(loop->function), ep);
 364         if (result)
 365                 goto out;
 366
 367         result = usb_ep_enable(ep);
 368         if (result < 0)
 369                 goto out;
 370         ep->driver_data = loop;
 371         result = 0;
 372
 373 out:
 374         return result;
 375 }
 376
 377 static int
 378 enable_loopback(struct usb_composite_dev *cdev, struct f_loopback *loop)
 379 {
 380         int                                     result = 0;
 381
 382         result = enable_endpoint(cdev, loop, loop->in_ep);
 383         if (result)
 384                 goto out;
 385
 386         result = enable_endpoint(cdev, loop, loop->out_ep);
 387         if (result)
 388                 goto disable_in;
 389
 390         result = alloc_requests(cdev, loop);
 391         if (result)
 392                 goto disable_out;
 393
 394         DBG(cdev, "%s enabled\n", loop->function.name);
 395         return 0;
 396
 397 disable_out:
 398         usb_ep_disable(loop->out_ep);
 399 disable_in:
 400         usb_ep_disable(loop->in_ep);
 401 out:
 402         return result;
 403 }
 404
 405 static int loopback_set_alt(struct usb_function *f,
 406                 unsigned intf, unsigned alt)
 407 {
 408         struct f_loopback       *loop = func_to_loop(f);
 409         struct usb_composite_dev *cdev = f->config->cdev;
 410
 411         /* we know alt is zero */
 412         disable_loopback(loop);
 413         return enable_loopback(cdev, loop);
 414 }
 415
 416 static void loopback_disable(struct usb_function *f)
 417 {
 418         struct f_loopback       *loop = func_to_loop(f);
 419
 420         disable_loopback(loop);
 421 }
 422
 423 static struct usb_function *loopback_alloc(struct usb_function_instance *fi)
 424 {
 425         struct f_loopback       *loop;
 426         struct f_lb_opts        *lb_opts;
 427
 428         loop = kzalloc(sizeof *loop, GFP_KERNEL);
 429         if (!loop)
 430                 return ERR_PTR(-ENOMEM);
 431
 432         lb_opts = container_of(fi, struct f_lb_opts, func_inst);
 433
 434         mutex_lock(&lb_opts->lock);
 435         lb_opts->refcnt++;
 436         mutex_unlock(&lb_opts->lock);
 437
 438         loop->buflen = lb_opts->bulk_buflen;
 439         loop->qlen = lb_opts->qlen;
 440         if (!loop->qlen)
 441                 loop->qlen = 32;
 442
 443         loop->function.name = "loopback";
 444         loop->function.bind = loopback_bind;
 445         loop->function.set_alt = loopback_set_alt;
 446         loop->function.disable = loopback_disable;
 447         loop->function.strings = loopback_strings;
 448
 449         loop->function.free_func = lb_free_func;
 450
 451         return &loop->function;
 452 }
 453
 454 static inline struct f_lb_opts *to_f_lb_opts(struct config_item *item)
 455 {
 456         return container_of(to_config_group(item), struct f_lb_opts,
 457                             func_inst.group);
 458 }
 459
 460 static void lb_attr_release(struct config_item *item)
 461 {
 462         struct f_lb_opts *lb_opts = to_f_lb_opts(item);
 463
 464         usb_put_function_instance(&lb_opts->func_inst);
 465 }
 466
 467 static struct configfs_item_operations lb_item_ops = {
 468         .release                = lb_attr_release,
 469 };
 470
 471 static ssize_t f_lb_opts_qlen_show(struct config_item *item, char *page)
 472 {
 473         struct f_lb_opts *opts = to_f_lb_opts(item);
 474         int result;
 475
 476         mutex_lock(&opts->lock);
 477         result = sprintf(page, "%d\n", opts->qlen);
 478         mutex_unlock(&opts->lock);
 479
 480         return result;
 481 }
 482
 483 static ssize_t f_lb_opts_qlen_store(struct config_item *item,
 484                                     const char *page, size_t len)
 485 {
 486         struct f_lb_opts *opts = to_f_lb_opts(item);
 487         int ret;
 488         u32 num;
 489
 490         mutex_lock(&opts->lock);
 491         if (opts->refcnt) {
 492                 ret = -EBUSY;
 493                 goto end;
 494         }
 495
 496         ret = kstrtou32(page, 0, &num);
 497         if (ret)
 498                 goto end;
 499
 500         opts->qlen = num;
 501         ret = len;
 502 end:
 503         mutex_unlock(&opts->lock);
 504         return ret;
 505 }
 506
 507 CONFIGFS_ATTR(f_lb_opts_, qlen);
 508
 509 static ssize_t f_lb_opts_bulk_buflen_show(struct config_item *item, char *page)
 510 {
 511         struct f_lb_opts *opts = to_f_lb_opts(item);
 512         int result;
 513
 514         mutex_lock(&opts->lock);
 515         result = sprintf(page, "%d\n", opts->bulk_buflen);
 516         mutex_unlock(&opts->lock);
 517
 518         return result;
 519 }
 520
 521 static ssize_t f_lb_opts_bulk_buflen_store(struct config_item *item,
 522                                     const char *page, size_t len)
 523 {
 524         struct f_lb_opts *opts = to_f_lb_opts(item);
 525         int ret;
 526         u32 num;
 527
 528         mutex_lock(&opts->lock);
 529         if (opts->refcnt) {
 530                 ret = -EBUSY;
 531                 goto end;
 532         }
 533
 534         ret = kstrtou32(page, 0, &num);
 535         if (ret)
 536                 goto end;
 537
 538         opts->bulk_buflen = num;
 539         ret = len;
 540 end:
 541         mutex_unlock(&opts->lock);
 542         return ret;
 543 }
 544
 545 CONFIGFS_ATTR(f_lb_opts_, bulk_buflen);
 546
 547 static struct configfs_attribute *lb_attrs[] = {
 548         &f_lb_opts_attr_qlen,
 549         &f_lb_opts_attr_bulk_buflen,
 550         NULL,
 551 };
 552
 553 static const struct config_item_type lb_func_type = {
 554         .ct_item_ops    = &lb_item_ops,
 555         .ct_attrs       = lb_attrs,
 556         .ct_owner       = THIS_MODULE,
 557 };
 558
 559 static void lb_free_instance(struct usb_function_instance *fi)
 560 {
 561         struct f_lb_opts *lb_opts;
 562
 563         lb_opts = container_of(fi, struct f_lb_opts, func_inst);
 564         kfree(lb_opts);
 565 }
 566
 567 static struct usb_function_instance *loopback_alloc_instance(void)
 568 {
 569         struct f_lb_opts *lb_opts;
 570
 571         lb_opts = kzalloc(sizeof(*lb_opts), GFP_KERNEL);
 572         if (!lb_opts)
 573                 return ERR_PTR(-ENOMEM);
 574         mutex_init(&lb_opts->lock);
 575         lb_opts->func_inst.free_func_inst = lb_free_instance;
 576         lb_opts->bulk_buflen = GZERO_BULK_BUFLEN;
 577         lb_opts->qlen = GZERO_QLEN;
 578
 579         config_group_init_type_name(&lb_opts->func_inst.group, "",
 580                                     &lb_func_type);
 581
 582         return  &lb_opts->func_inst;
 583 }
 584 DECLARE_USB_FUNCTION(Loopback, loopback_alloc_instance, loopback_alloc);
 585
 586 int __init lb_modinit(void)
 587 {
 588         return usb_function_register(&Loopbackusb_func);
 589 }
 590
 591 void __exit lb_modexit(void)
 592 {
 593         usb_function_unregister(&Loopbackusb_func);
 594 }
 595
 596 MODULE_LICENSE("GPL");