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