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 */
28struct 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
38static 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
45static 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
56static 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
64static 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
72static 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
81static 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
89static 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
97static 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
106static 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
114static 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
122static 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
130static 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
138static 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
149static struct usb_string strings_loopback[] = {
150 [0].s = "loop input to output",
151 { } /* end of list */
152};
153
154static struct usb_gadget_strings stringtab_loop = {
155 .language = 0x0409, /* en-us */
156 .strings = strings_loopback,
157};
158
159static struct usb_gadget_strings *loopback_strings[] = {
160 &stringtab_loop,
161 NULL,
162};
163
164/*-------------------------------------------------------------------------*/
165
166static 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(c: 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) {
189autoconf_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: fs_loopback_descs, hs: hs_loopback_descs,
210 ss: ss_loopback_descs, ssp: 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
219static 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(lock: &opts->lock);
228
229 usb_free_all_descriptors(f);
230 kfree(objp: func_to_loop(f));
231}
232
233static 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 */
285free_req:
286 usb_ep_free_request(ep: ep == loop->in_ep ?
287 loop->out_ep : loop->in_ep,
288 req: req->context);
289 free_ep_req(ep, req);
290 return;
291 }
292}
293
294static 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, in: loop->in_ep, out: loop->out_ep, NULL, NULL);
300 VDBG(cdev, "%s disabled\n", loop->function.name);
301}
302
303static inline struct usb_request *lb_alloc_ep_req(struct usb_ep *ep, int len)
304{
305 return alloc_ep_req(ep, len);
306}
307
308static 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(ep: loop->in_ep, GFP_ATOMIC);
325 if (!in_req)
326 goto fail;
327
328 out_req = lb_alloc_ep_req(ep: loop->out_ep, len: 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(ep: loop->out_ep, req: 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
350fail_out:
351 free_ep_req(ep: loop->out_ep, req: out_req);
352fail_in:
353 usb_ep_free_request(ep: loop->in_ep, req: in_req);
354fail:
355 return result;
356}
357
358static 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(g: cdev->gadget, f: &(loop->function), ep: 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
373out:
374 return result;
375}
376
377static int
378enable_loopback(struct usb_composite_dev *cdev, struct f_loopback *loop)
379{
380 int result = 0;
381
382 result = enable_endpoint(cdev, loop, ep: loop->in_ep);
383 if (result)
384 goto out;
385
386 result = enable_endpoint(cdev, loop, ep: 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
397disable_out:
398 usb_ep_disable(ep: loop->out_ep);
399disable_in:
400 usb_ep_disable(ep: loop->in_ep);
401out:
402 return result;
403}
404
405static 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
416static void loopback_disable(struct usb_function *f)
417{
418 struct f_loopback *loop = func_to_loop(f);
419
420 disable_loopback(loop);
421}
422
423static 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(error: -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(lock: &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
454static 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
460static 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(fi: &lb_opts->func_inst);
465}
466
467static struct configfs_item_operations lb_item_ops = {
468 .release = lb_attr_release,
469};
470
471static 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(buf: page, fmt: "%d\n", opts->qlen);
478 mutex_unlock(lock: &opts->lock);
479
480 return result;
481}
482
483static 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(s: page, base: 0, res: &num);
497 if (ret)
498 goto end;
499
500 opts->qlen = num;
501 ret = len;
502end:
503 mutex_unlock(lock: &opts->lock);
504 return ret;
505}
506
507CONFIGFS_ATTR(f_lb_opts_, qlen);
508
509static 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(buf: page, fmt: "%d\n", opts->bulk_buflen);
516 mutex_unlock(lock: &opts->lock);
517
518 return result;
519}
520
521static 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(s: page, base: 0, res: &num);
535 if (ret)
536 goto end;
537
538 opts->bulk_buflen = num;
539 ret = len;
540end:
541 mutex_unlock(lock: &opts->lock);
542 return ret;
543}
544
545CONFIGFS_ATTR(f_lb_opts_, bulk_buflen);
546
547static struct configfs_attribute *lb_attrs[] = {
548 &f_lb_opts_attr_qlen,
549 &f_lb_opts_attr_bulk_buflen,
550 NULL,
551};
552
553static 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
559static 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(objp: lb_opts);
565}
566
567static 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(error: -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(group: &lb_opts->func_inst.group, name: "",
580 type: &lb_func_type);
581
582 return &lb_opts->func_inst;
583}
584DECLARE_USB_FUNCTION(Loopback, loopback_alloc_instance, loopback_alloc);
585
586int __init lb_modinit(void)
587{
588 return usb_function_register(newf: &Loopbackusb_func);
589}
590
591void __exit lb_modexit(void)
592{
593 usb_function_unregister(f: &Loopbackusb_func);
594}
595
596MODULE_DESCRIPTION("USB peripheral loopback configuration driver");
597MODULE_LICENSE("GPL");
598

source code of linux/drivers/usb/gadget/function/f_loopback.c