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 #include <linux/usb/func_utils.h> 18 19 #include "g_zero.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_DESCRIPTION("USB peripheral loopback configuration driver"); 597 MODULE_LICENSE("GPL"); 598