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
func_to_loop(struct usb_function * f)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
loopback_bind(struct usb_configuration * c,struct usb_function * f)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, NULL);
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
lb_free_func(struct usb_function * f)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
loopback_complete(struct usb_ep * ep,struct usb_request * req)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
disable_loopback(struct f_loopback * loop)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
lb_alloc_ep_req(struct usb_ep * ep,int len)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
alloc_requests(struct usb_composite_dev * cdev,struct f_loopback * loop)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
enable_endpoint(struct usb_composite_dev * cdev,struct f_loopback * loop,struct usb_ep * ep)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
enable_loopback(struct usb_composite_dev * cdev,struct f_loopback * loop)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
loopback_set_alt(struct usb_function * f,unsigned intf,unsigned alt)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
loopback_disable(struct usb_function * f)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
loopback_alloc(struct usb_function_instance * fi)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
to_f_lb_opts(struct config_item * item)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
lb_attr_release(struct config_item * item)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
f_lb_opts_qlen_show(struct config_item * item,char * page)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
f_lb_opts_qlen_store(struct config_item * item,const char * page,size_t len)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
f_lb_opts_bulk_buflen_show(struct config_item * item,char * page)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
f_lb_opts_bulk_buflen_store(struct config_item * item,const char * page,size_t len)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
lb_free_instance(struct usb_function_instance * fi)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
loopback_alloc_instance(void)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
lb_modinit(void)588 int __init lb_modinit(void)
589 {
590 return usb_function_register(&Loopbackusb_func);
591 }
592
lb_modexit(void)593 void __exit lb_modexit(void)
594 {
595 usb_function_unregister(&Loopbackusb_func);
596 }
597
598 MODULE_LICENSE("GPL");
599
