1 // SPDX-License-Identifier: GPL-2.0+
3 * f_loopback.c - USB peripheral loopback configuration driver
5 * Copyright (C) 2003-2008 David Brownell
6 * Copyright (C) 2008 by Nokia Corporation
9 /* #define VERBOSE_DEBUG */
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>
22 * LOOPBACK FUNCTION ... a testing vehicle for USB peripherals,
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.
29 struct usb_function function;
32 struct usb_ep *out_ep;
38 static inline struct f_loopback *func_to_loop(struct usb_function *f)
40 return container_of(f, struct f_loopback, function);
43 /*-------------------------------------------------------------------------*/
45 static struct usb_interface_descriptor loopback_intf = {
46 .bLength = sizeof(loopback_intf),
47 .bDescriptorType = USB_DT_INTERFACE,
50 .bInterfaceClass = USB_CLASS_VENDOR_SPEC,
51 /* .iInterface = DYNAMIC */
54 /* full speed support: */
56 static struct usb_endpoint_descriptor fs_loop_source_desc = {
57 .bLength = USB_DT_ENDPOINT_SIZE,
58 .bDescriptorType = USB_DT_ENDPOINT,
60 .bEndpointAddress = USB_DIR_IN,
61 .bmAttributes = USB_ENDPOINT_XFER_BULK,
64 static struct usb_endpoint_descriptor fs_loop_sink_desc = {
65 .bLength = USB_DT_ENDPOINT_SIZE,
66 .bDescriptorType = USB_DT_ENDPOINT,
68 .bEndpointAddress = USB_DIR_OUT,
69 .bmAttributes = USB_ENDPOINT_XFER_BULK,
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,
79 /* high speed support: */
81 static struct usb_endpoint_descriptor hs_loop_source_desc = {
82 .bLength = USB_DT_ENDPOINT_SIZE,
83 .bDescriptorType = USB_DT_ENDPOINT,
85 .bmAttributes = USB_ENDPOINT_XFER_BULK,
86 .wMaxPacketSize = cpu_to_le16(512),
89 static struct usb_endpoint_descriptor hs_loop_sink_desc = {
90 .bLength = USB_DT_ENDPOINT_SIZE,
91 .bDescriptorType = USB_DT_ENDPOINT,
93 .bmAttributes = USB_ENDPOINT_XFER_BULK,
94 .wMaxPacketSize = cpu_to_le16(512),
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,
104 /* super speed support: */
106 static struct usb_endpoint_descriptor ss_loop_source_desc = {
107 .bLength = USB_DT_ENDPOINT_SIZE,
108 .bDescriptorType = USB_DT_ENDPOINT,
110 .bmAttributes = USB_ENDPOINT_XFER_BULK,
111 .wMaxPacketSize = cpu_to_le16(1024),
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,
119 .wBytesPerInterval = 0,
122 static struct usb_endpoint_descriptor ss_loop_sink_desc = {
123 .bLength = USB_DT_ENDPOINT_SIZE,
124 .bDescriptorType = USB_DT_ENDPOINT,
126 .bmAttributes = USB_ENDPOINT_XFER_BULK,
127 .wMaxPacketSize = cpu_to_le16(1024),
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,
135 .wBytesPerInterval = 0,
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,
147 /* function-specific strings: */
149 static struct usb_string strings_loopback[] = {
150 [0].s = "loop input to output",
151 { } /* end of list */
154 static struct usb_gadget_strings stringtab_loop = {
155 .language = 0x0409, /* en-us */
156 .strings = strings_loopback,
159 static struct usb_gadget_strings *loopback_strings[] = {
164 /*-------------------------------------------------------------------------*/
166 static int loopback_bind(struct usb_configuration *c, struct usb_function *f)
168 struct usb_composite_dev *cdev = c->cdev;
169 struct f_loopback *loop = func_to_loop(f);
173 /* allocate interface ID(s) */
174 id = usb_interface_id(c, f);
177 loopback_intf.bInterfaceNumber = id;
179 id = usb_string_id(cdev);
182 strings_loopback[0].id = id;
183 loopback_intf.iInterface = id;
185 /* allocate endpoints */
187 loop->in_ep = usb_ep_autoconfig(cdev->gadget, &fs_loop_source_desc);
190 ERROR(cdev, "%s: can't autoconfigure on %s\n",
191 f->name, cdev->gadget->name);
195 loop->out_ep = usb_ep_autoconfig(cdev->gadget, &fs_loop_sink_desc);
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;
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;
209 ret = usb_assign_descriptors(f, fs_loopback_descs, hs_loopback_descs,
210 ss_loopback_descs, ss_loopback_descs);
214 DBG(cdev, "%s: IN/%s, OUT/%s\n",
215 f->name, loop->in_ep->name, loop->out_ep->name);
219 static void lb_free_func(struct usb_function *f)
221 struct f_lb_opts *opts;
223 opts = container_of(f->fi, struct f_lb_opts, func_inst);
225 mutex_lock(&opts->lock);
227 mutex_unlock(&opts->lock);
229 usb_free_all_descriptors(f);
230 kfree(func_to_loop(f));
233 static void loopback_complete(struct usb_ep *ep, struct usb_request *req)
235 struct f_loopback *loop = ep->driver_data;
236 struct usb_composite_dev *cdev = loop->function.config->cdev;
237 int status = req->status;
240 case 0: /* normal completion? */
241 if (ep == loop->out_ep) {
243 * We received some data from the host so let's
244 * queue it so host can read the from our in ep
246 struct usb_request *in_req = req->context;
248 in_req->zero = (req->actual < req->length);
249 in_req->length = req->actual;
254 * We have just looped back a bunch of data
255 * to host. Now let's wait for some more data.
261 /* queue the buffer back to host or for next bunch of data */
262 status = usb_ep_queue(ep, req, GFP_ATOMIC);
266 ERROR(cdev, "Unable to loop back buffer to %s: %d\n",
271 /* "should never get here" */
273 ERROR(cdev, "%s loop complete --> %d, %d/%d\n", ep->name,
274 status, req->actual, req->length);
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
282 case -ECONNABORTED: /* hardware forced ep reset */
283 case -ECONNRESET: /* request dequeued */
284 case -ESHUTDOWN: /* disconnect from host */
286 usb_ep_free_request(ep == loop->in_ep ?
287 loop->out_ep : loop->in_ep,
289 free_ep_req(ep, req);
294 static void disable_loopback(struct f_loopback *loop)
296 struct usb_composite_dev *cdev;
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);
303 static inline struct usb_request *lb_alloc_ep_req(struct usb_ep *ep, int len)
305 return alloc_ep_req(ep, len);
308 static int alloc_requests(struct usb_composite_dev *cdev,
309 struct f_loopback *loop)
311 struct usb_request *in_req, *out_req;
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
321 for (i = 0; i < loop->qlen && result == 0; i++) {
324 in_req = usb_ep_alloc_request(loop->in_ep, GFP_ATOMIC);
328 out_req = lb_alloc_ep_req(loop->out_ep, loop->buflen);
332 in_req->complete = loopback_complete;
333 out_req->complete = loopback_complete;
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;
340 result = usb_ep_queue(loop->out_ep, out_req, GFP_ATOMIC);
342 ERROR(cdev, "%s queue req --> %d\n",
343 loop->out_ep->name, result);
351 free_ep_req(loop->out_ep, out_req);
353 usb_ep_free_request(loop->in_ep, in_req);
358 static int enable_endpoint(struct usb_composite_dev *cdev,
359 struct f_loopback *loop, struct usb_ep *ep)
363 result = config_ep_by_speed(cdev->gadget, &(loop->function), ep);
367 result = usb_ep_enable(ep);
370 ep->driver_data = loop;
378 enable_loopback(struct usb_composite_dev *cdev, struct f_loopback *loop)
382 result = enable_endpoint(cdev, loop, loop->in_ep);
386 result = enable_endpoint(cdev, loop, loop->out_ep);
390 result = alloc_requests(cdev, loop);
394 DBG(cdev, "%s enabled\n", loop->function.name);
398 usb_ep_disable(loop->out_ep);
400 usb_ep_disable(loop->in_ep);
405 static int loopback_set_alt(struct usb_function *f,
406 unsigned intf, unsigned alt)
408 struct f_loopback *loop = func_to_loop(f);
409 struct usb_composite_dev *cdev = f->config->cdev;
411 /* we know alt is zero */
412 disable_loopback(loop);
413 return enable_loopback(cdev, loop);
416 static void loopback_disable(struct usb_function *f)
418 struct f_loopback *loop = func_to_loop(f);
420 disable_loopback(loop);
423 static struct usb_function *loopback_alloc(struct usb_function_instance *fi)
425 struct f_loopback *loop;
426 struct f_lb_opts *lb_opts;
428 loop = kzalloc(sizeof *loop, GFP_KERNEL);
430 return ERR_PTR(-ENOMEM);
432 lb_opts = container_of(fi, struct f_lb_opts, func_inst);
434 mutex_lock(&lb_opts->lock);
436 mutex_unlock(&lb_opts->lock);
438 loop->buflen = lb_opts->bulk_buflen;
439 loop->qlen = lb_opts->qlen;
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;
449 loop->function.free_func = lb_free_func;
451 return &loop->function;
454 static inline struct f_lb_opts *to_f_lb_opts(struct config_item *item)
456 return container_of(to_config_group(item), struct f_lb_opts,
460 static void lb_attr_release(struct config_item *item)
462 struct f_lb_opts *lb_opts = to_f_lb_opts(item);
464 usb_put_function_instance(&lb_opts->func_inst);
467 static struct configfs_item_operations lb_item_ops = {
468 .release = lb_attr_release,
471 static ssize_t f_lb_opts_qlen_show(struct config_item *item, char *page)
473 struct f_lb_opts *opts = to_f_lb_opts(item);
476 mutex_lock(&opts->lock);
477 result = sprintf(page, "%d\n", opts->qlen);
478 mutex_unlock(&opts->lock);
483 static ssize_t f_lb_opts_qlen_store(struct config_item *item,
484 const char *page, size_t len)
486 struct f_lb_opts *opts = to_f_lb_opts(item);
490 mutex_lock(&opts->lock);
496 ret = kstrtou32(page, 0, &num);
503 mutex_unlock(&opts->lock);
507 CONFIGFS_ATTR(f_lb_opts_, qlen);
509 static ssize_t f_lb_opts_bulk_buflen_show(struct config_item *item, char *page)
511 struct f_lb_opts *opts = to_f_lb_opts(item);
514 mutex_lock(&opts->lock);
515 result = sprintf(page, "%d\n", opts->bulk_buflen);
516 mutex_unlock(&opts->lock);
521 static ssize_t f_lb_opts_bulk_buflen_store(struct config_item *item,
522 const char *page, size_t len)
524 struct f_lb_opts *opts = to_f_lb_opts(item);
528 mutex_lock(&opts->lock);
534 ret = kstrtou32(page, 0, &num);
538 opts->bulk_buflen = num;
541 mutex_unlock(&opts->lock);
545 CONFIGFS_ATTR(f_lb_opts_, bulk_buflen);
547 static struct configfs_attribute *lb_attrs[] = {
548 &f_lb_opts_attr_qlen,
549 &f_lb_opts_attr_bulk_buflen,
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,
559 static void lb_free_instance(struct usb_function_instance *fi)
561 struct f_lb_opts *lb_opts;
563 lb_opts = container_of(fi, struct f_lb_opts, func_inst);
567 static struct usb_function_instance *loopback_alloc_instance(void)
569 struct f_lb_opts *lb_opts;
571 lb_opts = kzalloc(sizeof(*lb_opts), GFP_KERNEL);
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;
579 config_group_init_type_name(&lb_opts->func_inst.group, "",
582 return &lb_opts->func_inst;
584 DECLARE_USB_FUNCTION(Loopback, loopback_alloc_instance, loopback_alloc);
586 int __init lb_modinit(void)
588 return usb_function_register(&Loopbackusb_func);
591 void __exit lb_modexit(void)
593 usb_function_unregister(&Loopbackusb_func);
596 MODULE_LICENSE("GPL");