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");
597