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 speed %s: IN/%s, OUT/%s\n", 215 (gadget_is_superspeed(c->cdev->gadget) ? "super" : 216 (gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full")), 217 f->name, loop->in_ep->name, loop->out_ep->name); 218 return 0; 219 } 220 221 static void lb_free_func(struct usb_function *f) 222 { 223 struct f_lb_opts *opts; 224 225 opts = container_of(f->fi, struct f_lb_opts, func_inst); 226 227 mutex_lock(&opts->lock); 228 opts->refcnt--; 229 mutex_unlock(&opts->lock); 230 231 usb_free_all_descriptors(f); 232 kfree(func_to_loop(f)); 233 } 234 235 static void loopback_complete(struct usb_ep *ep, struct usb_request *req) 236 { 237 struct f_loopback *loop = ep->driver_data; 238 struct usb_composite_dev *cdev = loop->function.config->cdev; 239 int status = req->status; 240 241 switch (status) { 242 case 0: /* normal completion? */ 243 if (ep == loop->out_ep) { 244 /* 245 * We received some data from the host so let's 246 * queue it so host can read the from our in ep 247 */ 248 struct usb_request *in_req = req->context; 249 250 in_req->zero = (req->actual < req->length); 251 in_req->length = req->actual; 252 ep = loop->in_ep; 253 req = in_req; 254 } else { 255 /* 256 * We have just looped back a bunch of data 257 * to host. Now let's wait for some more data. 258 */ 259 req = req->context; 260 ep = loop->out_ep; 261 } 262 263 /* queue the buffer back to host or for next bunch of data */ 264 status = usb_ep_queue(ep, req, GFP_ATOMIC); 265 if (status == 0) { 266 return; 267 } else { 268 ERROR(cdev, "Unable to loop back buffer to %s: %d\n", 269 ep->name, status); 270 goto free_req; 271 } 272 273 /* "should never get here" */ 274 default: 275 ERROR(cdev, "%s loop complete --> %d, %d/%d\n", ep->name, 276 status, req->actual, req->length); 277 fallthrough; 278 279 /* NOTE: since this driver doesn't maintain an explicit record 280 * of requests it submitted (just maintains qlen count), we 281 * rely on the hardware driver to clean up on disconnect or 282 * endpoint disable. 283 */ 284 case -ECONNABORTED: /* hardware forced ep reset */ 285 case -ECONNRESET: /* request dequeued */ 286 case -ESHUTDOWN: /* disconnect from host */ 287 free_req: 288 usb_ep_free_request(ep == loop->in_ep ? 289 loop->out_ep : loop->in_ep, 290 req->context); 291 free_ep_req(ep, req); 292 return; 293 } 294 } 295 296 static void disable_loopback(struct f_loopback *loop) 297 { 298 struct usb_composite_dev *cdev; 299 300 cdev = loop->function.config->cdev; 301 disable_endpoints(cdev, loop->in_ep, loop->out_ep, NULL, NULL); 302 VDBG(cdev, "%s disabled\n", loop->function.name); 303 } 304 305 static inline struct usb_request *lb_alloc_ep_req(struct usb_ep *ep, int len) 306 { 307 return alloc_ep_req(ep, len); 308 } 309 310 static int alloc_requests(struct usb_composite_dev *cdev, 311 struct f_loopback *loop) 312 { 313 struct usb_request *in_req, *out_req; 314 int i; 315 int result = 0; 316 317 /* 318 * allocate a bunch of read buffers and queue them all at once. 319 * we buffer at most 'qlen' transfers; We allocate buffers only 320 * for out transfer and reuse them in IN transfers to implement 321 * our loopback functionality 322 */ 323 for (i = 0; i < loop->qlen && result == 0; i++) { 324 result = -ENOMEM; 325 326 in_req = usb_ep_alloc_request(loop->in_ep, GFP_ATOMIC); 327 if (!in_req) 328 goto fail; 329 330 out_req = lb_alloc_ep_req(loop->out_ep, loop->buflen); 331 if (!out_req) 332 goto fail_in; 333 334 in_req->complete = loopback_complete; 335 out_req->complete = loopback_complete; 336 337 in_req->buf = out_req->buf; 338 /* length will be set in complete routine */ 339 in_req->context = out_req; 340 out_req->context = in_req; 341 342 result = usb_ep_queue(loop->out_ep, out_req, GFP_ATOMIC); 343 if (result) { 344 ERROR(cdev, "%s queue req --> %d\n", 345 loop->out_ep->name, result); 346 goto fail_out; 347 } 348 } 349 350 return 0; 351 352 fail_out: 353 free_ep_req(loop->out_ep, out_req); 354 fail_in: 355 usb_ep_free_request(loop->in_ep, in_req); 356 fail: 357 return result; 358 } 359 360 static int enable_endpoint(struct usb_composite_dev *cdev, 361 struct f_loopback *loop, struct usb_ep *ep) 362 { 363 int result; 364 365 result = config_ep_by_speed(cdev->gadget, &(loop->function), ep); 366 if (result) 367 goto out; 368 369 result = usb_ep_enable(ep); 370 if (result < 0) 371 goto out; 372 ep->driver_data = loop; 373 result = 0; 374 375 out: 376 return result; 377 } 378 379 static int 380 enable_loopback(struct usb_composite_dev *cdev, struct f_loopback *loop) 381 { 382 int result = 0; 383 384 result = enable_endpoint(cdev, loop, loop->in_ep); 385 if (result) 386 goto out; 387 388 result = enable_endpoint(cdev, loop, loop->out_ep); 389 if (result) 390 goto disable_in; 391 392 result = alloc_requests(cdev, loop); 393 if (result) 394 goto disable_out; 395 396 DBG(cdev, "%s enabled\n", loop->function.name); 397 return 0; 398 399 disable_out: 400 usb_ep_disable(loop->out_ep); 401 disable_in: 402 usb_ep_disable(loop->in_ep); 403 out: 404 return result; 405 } 406 407 static int loopback_set_alt(struct usb_function *f, 408 unsigned intf, unsigned alt) 409 { 410 struct f_loopback *loop = func_to_loop(f); 411 struct usb_composite_dev *cdev = f->config->cdev; 412 413 /* we know alt is zero */ 414 disable_loopback(loop); 415 return enable_loopback(cdev, loop); 416 } 417 418 static void loopback_disable(struct usb_function *f) 419 { 420 struct f_loopback *loop = func_to_loop(f); 421 422 disable_loopback(loop); 423 } 424 425 static struct usb_function *loopback_alloc(struct usb_function_instance *fi) 426 { 427 struct f_loopback *loop; 428 struct f_lb_opts *lb_opts; 429 430 loop = kzalloc(sizeof *loop, GFP_KERNEL); 431 if (!loop) 432 return ERR_PTR(-ENOMEM); 433 434 lb_opts = container_of(fi, struct f_lb_opts, func_inst); 435 436 mutex_lock(&lb_opts->lock); 437 lb_opts->refcnt++; 438 mutex_unlock(&lb_opts->lock); 439 440 loop->buflen = lb_opts->bulk_buflen; 441 loop->qlen = lb_opts->qlen; 442 if (!loop->qlen) 443 loop->qlen = 32; 444 445 loop->function.name = "loopback"; 446 loop->function.bind = loopback_bind; 447 loop->function.set_alt = loopback_set_alt; 448 loop->function.disable = loopback_disable; 449 loop->function.strings = loopback_strings; 450 451 loop->function.free_func = lb_free_func; 452 453 return &loop->function; 454 } 455 456 static inline struct f_lb_opts *to_f_lb_opts(struct config_item *item) 457 { 458 return container_of(to_config_group(item), struct f_lb_opts, 459 func_inst.group); 460 } 461 462 static void lb_attr_release(struct config_item *item) 463 { 464 struct f_lb_opts *lb_opts = to_f_lb_opts(item); 465 466 usb_put_function_instance(&lb_opts->func_inst); 467 } 468 469 static struct configfs_item_operations lb_item_ops = { 470 .release = lb_attr_release, 471 }; 472 473 static ssize_t f_lb_opts_qlen_show(struct config_item *item, char *page) 474 { 475 struct f_lb_opts *opts = to_f_lb_opts(item); 476 int result; 477 478 mutex_lock(&opts->lock); 479 result = sprintf(page, "%d\n", opts->qlen); 480 mutex_unlock(&opts->lock); 481 482 return result; 483 } 484 485 static ssize_t f_lb_opts_qlen_store(struct config_item *item, 486 const char *page, size_t len) 487 { 488 struct f_lb_opts *opts = to_f_lb_opts(item); 489 int ret; 490 u32 num; 491 492 mutex_lock(&opts->lock); 493 if (opts->refcnt) { 494 ret = -EBUSY; 495 goto end; 496 } 497 498 ret = kstrtou32(page, 0, &num); 499 if (ret) 500 goto end; 501 502 opts->qlen = num; 503 ret = len; 504 end: 505 mutex_unlock(&opts->lock); 506 return ret; 507 } 508 509 CONFIGFS_ATTR(f_lb_opts_, qlen); 510 511 static ssize_t f_lb_opts_bulk_buflen_show(struct config_item *item, char *page) 512 { 513 struct f_lb_opts *opts = to_f_lb_opts(item); 514 int result; 515 516 mutex_lock(&opts->lock); 517 result = sprintf(page, "%d\n", opts->bulk_buflen); 518 mutex_unlock(&opts->lock); 519 520 return result; 521 } 522 523 static ssize_t f_lb_opts_bulk_buflen_store(struct config_item *item, 524 const char *page, size_t len) 525 { 526 struct f_lb_opts *opts = to_f_lb_opts(item); 527 int ret; 528 u32 num; 529 530 mutex_lock(&opts->lock); 531 if (opts->refcnt) { 532 ret = -EBUSY; 533 goto end; 534 } 535 536 ret = kstrtou32(page, 0, &num); 537 if (ret) 538 goto end; 539 540 opts->bulk_buflen = num; 541 ret = len; 542 end: 543 mutex_unlock(&opts->lock); 544 return ret; 545 } 546 547 CONFIGFS_ATTR(f_lb_opts_, bulk_buflen); 548 549 static struct configfs_attribute *lb_attrs[] = { 550 &f_lb_opts_attr_qlen, 551 &f_lb_opts_attr_bulk_buflen, 552 NULL, 553 }; 554 555 static const struct config_item_type lb_func_type = { 556 .ct_item_ops = &lb_item_ops, 557 .ct_attrs = lb_attrs, 558 .ct_owner = THIS_MODULE, 559 }; 560 561 static void lb_free_instance(struct usb_function_instance *fi) 562 { 563 struct f_lb_opts *lb_opts; 564 565 lb_opts = container_of(fi, struct f_lb_opts, func_inst); 566 kfree(lb_opts); 567 } 568 569 static struct usb_function_instance *loopback_alloc_instance(void) 570 { 571 struct f_lb_opts *lb_opts; 572 573 lb_opts = kzalloc(sizeof(*lb_opts), GFP_KERNEL); 574 if (!lb_opts) 575 return ERR_PTR(-ENOMEM); 576 mutex_init(&lb_opts->lock); 577 lb_opts->func_inst.free_func_inst = lb_free_instance; 578 lb_opts->bulk_buflen = GZERO_BULK_BUFLEN; 579 lb_opts->qlen = GZERO_QLEN; 580 581 config_group_init_type_name(&lb_opts->func_inst.group, "", 582 &lb_func_type); 583 584 return &lb_opts->func_inst; 585 } 586 DECLARE_USB_FUNCTION(Loopback, loopback_alloc_instance, loopback_alloc); 587 588 int __init lb_modinit(void) 589 { 590 return usb_function_register(&Loopbackusb_func); 591 } 592 593 void __exit lb_modexit(void) 594 { 595 usb_function_unregister(&Loopbackusb_func); 596 } 597 598 MODULE_LICENSE("GPL"); 599