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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * f_eem.c -- USB CDC Ethernet (EEM) link function driver
4 *
5 * Copyright (C) 2003-2005,2008 David Brownell
6 * Copyright (C) 2008 Nokia Corporation
7 * Copyright (C) 2009 EF Johnson Technologies
8 */
9
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/device.h>
13#include <linux/etherdevice.h>
14#include <linux/crc32.h>
15#include <linux/slab.h>
16
17#include "u_ether.h"
18#include "u_ether_configfs.h"
19#include "u_eem.h"
20
21#define EEM_HLEN 2
22
23/*
24 * This function is a "CDC Ethernet Emulation Model" (CDC EEM)
25 * Ethernet link.
26 */
27
28struct f_eem {
29 struct gether port;
30 u8 ctrl_id;
31};
32
33static inline struct f_eem *func_to_eem(struct usb_function *f)
34{
35 return container_of(f, struct f_eem, port.func);
36}
37
38/*-------------------------------------------------------------------------*/
39
40/* interface descriptor: */
41
42static struct usb_interface_descriptor eem_intf = {
43 .bLength = sizeof eem_intf,
44 .bDescriptorType = USB_DT_INTERFACE,
45
46 /* .bInterfaceNumber = DYNAMIC */
47 .bNumEndpoints = 2,
48 .bInterfaceClass = USB_CLASS_COMM,
49 .bInterfaceSubClass = USB_CDC_SUBCLASS_EEM,
50 .bInterfaceProtocol = USB_CDC_PROTO_EEM,
51 /* .iInterface = DYNAMIC */
52};
53
54/* full speed support: */
55
56static struct usb_endpoint_descriptor eem_fs_in_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 eem_fs_out_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 *eem_fs_function[] = {
73 /* CDC EEM control descriptors */
74 (struct usb_descriptor_header *) &eem_intf,
75 (struct usb_descriptor_header *) &eem_fs_in_desc,
76 (struct usb_descriptor_header *) &eem_fs_out_desc,
77 NULL,
78};
79
80/* high speed support: */
81
82static struct usb_endpoint_descriptor eem_hs_in_desc = {
83 .bLength = USB_DT_ENDPOINT_SIZE,
84 .bDescriptorType = USB_DT_ENDPOINT,
85
86 .bEndpointAddress = USB_DIR_IN,
87 .bmAttributes = USB_ENDPOINT_XFER_BULK,
88 .wMaxPacketSize = cpu_to_le16(512),
89};
90
91static struct usb_endpoint_descriptor eem_hs_out_desc = {
92 .bLength = USB_DT_ENDPOINT_SIZE,
93 .bDescriptorType = USB_DT_ENDPOINT,
94
95 .bEndpointAddress = USB_DIR_OUT,
96 .bmAttributes = USB_ENDPOINT_XFER_BULK,
97 .wMaxPacketSize = cpu_to_le16(512),
98};
99
100static struct usb_descriptor_header *eem_hs_function[] = {
101 /* CDC EEM control descriptors */
102 (struct usb_descriptor_header *) &eem_intf,
103 (struct usb_descriptor_header *) &eem_hs_in_desc,
104 (struct usb_descriptor_header *) &eem_hs_out_desc,
105 NULL,
106};
107
108/* super speed support: */
109
110static struct usb_endpoint_descriptor eem_ss_in_desc = {
111 .bLength = USB_DT_ENDPOINT_SIZE,
112 .bDescriptorType = USB_DT_ENDPOINT,
113
114 .bEndpointAddress = USB_DIR_IN,
115 .bmAttributes = USB_ENDPOINT_XFER_BULK,
116 .wMaxPacketSize = cpu_to_le16(1024),
117};
118
119static struct usb_endpoint_descriptor eem_ss_out_desc = {
120 .bLength = USB_DT_ENDPOINT_SIZE,
121 .bDescriptorType = USB_DT_ENDPOINT,
122
123 .bEndpointAddress = USB_DIR_OUT,
124 .bmAttributes = USB_ENDPOINT_XFER_BULK,
125 .wMaxPacketSize = cpu_to_le16(1024),
126};
127
128static struct usb_ss_ep_comp_descriptor eem_ss_bulk_comp_desc = {
129 .bLength = sizeof eem_ss_bulk_comp_desc,
130 .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
131
132 /* the following 2 values can be tweaked if necessary */
133 /* .bMaxBurst = 0, */
134 /* .bmAttributes = 0, */
135};
136
137static struct usb_descriptor_header *eem_ss_function[] = {
138 /* CDC EEM control descriptors */
139 (struct usb_descriptor_header *) &eem_intf,
140 (struct usb_descriptor_header *) &eem_ss_in_desc,
141 (struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
142 (struct usb_descriptor_header *) &eem_ss_out_desc,
143 (struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
144 NULL,
145};
146
147/* string descriptors: */
148
149static struct usb_string eem_string_defs[] = {
150 [0].s = "CDC Ethernet Emulation Model (EEM)",
151 { } /* end of list */
152};
153
154static struct usb_gadget_strings eem_string_table = {
155 .language = 0x0409, /* en-us */
156 .strings = eem_string_defs,
157};
158
159static struct usb_gadget_strings *eem_strings[] = {
160 &eem_string_table,
161 NULL,
162};
163
164/*-------------------------------------------------------------------------*/
165
166static int eem_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
167{
168 struct usb_composite_dev *cdev = f->config->cdev;
169 u16 w_index = le16_to_cpu(ctrl->wIndex);
170 u16 w_value = le16_to_cpu(ctrl->wValue);
171 u16 w_length = le16_to_cpu(ctrl->wLength);
172
173 DBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
174 ctrl->bRequestType, ctrl->bRequest,
175 w_value, w_index, w_length);
176
177 /* device either stalls (value < 0) or reports success */
178 return -EOPNOTSUPP;
179}
180
181
182static int eem_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
183{
184 struct f_eem *eem = func_to_eem(f);
185 struct usb_composite_dev *cdev = f->config->cdev;
186 struct net_device *net;
187
188 /* we know alt == 0, so this is an activation or a reset */
189 if (alt != 0)
190 goto fail;
191
192 if (intf == eem->ctrl_id) {
193 DBG(cdev, "reset eem\n");
194 gether_disconnect(&eem->port);
195
196 if (!eem->port.in_ep->desc || !eem->port.out_ep->desc) {
197 DBG(cdev, "init eem\n");
198 if (config_ep_by_speed(cdev->gadget, f,
199 eem->port.in_ep) ||
200 config_ep_by_speed(cdev->gadget, f,
201 eem->port.out_ep)) {
202 eem->port.in_ep->desc = NULL;
203 eem->port.out_ep->desc = NULL;
204 goto fail;
205 }
206 }
207
208 /* zlps should not occur because zero-length EEM packets
209 * will be inserted in those cases where they would occur
210 */
211 eem->port.is_zlp_ok = 1;
212 eem->port.cdc_filter = DEFAULT_FILTER;
213 DBG(cdev, "activate eem\n");
214 net = gether_connect(&eem->port);
215 if (IS_ERR(net))
216 return PTR_ERR(net);
217 } else
218 goto fail;
219
220 return 0;
221fail:
222 return -EINVAL;
223}
224
225static void eem_disable(struct usb_function *f)
226{
227 struct f_eem *eem = func_to_eem(f);
228 struct usb_composite_dev *cdev = f->config->cdev;
229
230 DBG(cdev, "eem deactivated\n");
231
232 if (eem->port.in_ep->enabled)
233 gether_disconnect(&eem->port);
234}
235
236/*-------------------------------------------------------------------------*/
237
238/* EEM function driver setup/binding */
239
240static int eem_bind(struct usb_configuration *c, struct usb_function *f)
241{
242 struct usb_composite_dev *cdev = c->cdev;
243 struct f_eem *eem = func_to_eem(f);
244 struct usb_string *us;
245 int status;
246 struct usb_ep *ep;
247
248 struct f_eem_opts *eem_opts;
249
250 eem_opts = container_of(f->fi, struct f_eem_opts, func_inst);
251 /*
252 * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
253 * configurations are bound in sequence with list_for_each_entry,
254 * in each configuration its functions are bound in sequence
255 * with list_for_each_entry, so we assume no race condition
256 * with regard to eem_opts->bound access
257 */
258 if (!eem_opts->bound) {
259 mutex_lock(&eem_opts->lock);
260 gether_set_gadget(eem_opts->net, cdev->gadget);
261 status = gether_register_netdev(eem_opts->net);
262 mutex_unlock(&eem_opts->lock);
263 if (status)
264 return status;
265 eem_opts->bound = true;
266 }
267
268 us = usb_gstrings_attach(cdev, eem_strings,
269 ARRAY_SIZE(eem_string_defs));
270 if (IS_ERR(us))
271 return PTR_ERR(us);
272 eem_intf.iInterface = us[0].id;
273
274 /* allocate instance-specific interface IDs */
275 status = usb_interface_id(c, f);
276 if (status < 0)
277 goto fail;
278 eem->ctrl_id = status;
279 eem_intf.bInterfaceNumber = status;
280
281 status = -ENODEV;
282
283 /* allocate instance-specific endpoints */
284 ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_in_desc);
285 if (!ep)
286 goto fail;
287 eem->port.in_ep = ep;
288
289 ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_out_desc);
290 if (!ep)
291 goto fail;
292 eem->port.out_ep = ep;
293
294 status = -ENOMEM;
295
296 /* support all relevant hardware speeds... we expect that when
297 * hardware is dual speed, all bulk-capable endpoints work at
298 * both speeds
299 */
300 eem_hs_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
301 eem_hs_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
302
303 eem_ss_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
304 eem_ss_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
305
306 status = usb_assign_descriptors(f, eem_fs_function, eem_hs_function,
307 eem_ss_function, NULL);
308 if (status)
309 goto fail;
310
311 DBG(cdev, "CDC Ethernet (EEM): %s speed IN/%s OUT/%s\n",
312 gadget_is_superspeed(c->cdev->gadget) ? "super" :
313 gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
314 eem->port.in_ep->name, eem->port.out_ep->name);
315 return 0;
316
317fail:
318 ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
319
320 return status;
321}
322
323static void eem_cmd_complete(struct usb_ep *ep, struct usb_request *req)
324{
325 struct sk_buff *skb = (struct sk_buff *)req->context;
326
327 dev_kfree_skb_any(skb);
328}
329
330/*
331 * Add the EEM header and ethernet checksum.
332 * We currently do not attempt to put multiple ethernet frames
333 * into a single USB transfer
334 */
335static struct sk_buff *eem_wrap(struct gether *port, struct sk_buff *skb)
336{
337 struct sk_buff *skb2 = NULL;
338 struct usb_ep *in = port->in_ep;
339 int headroom, tailroom, padlen = 0;
340 u16 len;
341
342 if (!skb)
343 return NULL;
344
345 len = skb->len;
346 headroom = skb_headroom(skb);
347 tailroom = skb_tailroom(skb);
348
349 /* When (len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) is 0,
350 * stick two bytes of zero-length EEM packet on the end.
351 */
352 if (((len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) == 0)
353 padlen += 2;
354
355 if ((tailroom >= (ETH_FCS_LEN + padlen)) &&
356 (headroom >= EEM_HLEN) && !skb_cloned(skb))
357 goto done;
358
359 skb2 = skb_copy_expand(skb, EEM_HLEN, ETH_FCS_LEN + padlen, GFP_ATOMIC);
360 dev_kfree_skb_any(skb);
361 skb = skb2;
362 if (!skb)
363 return skb;
364
365done:
366 /* use the "no CRC" option */
367 put_unaligned_be32(0xdeadbeef, skb_put(skb, 4));
368
369 /* EEM packet header format:
370 * b0..13: length of ethernet frame
371 * b14: bmCRC (0 == sentinel CRC)
372 * b15: bmType (0 == data)
373 */
374 len = skb->len;
375 put_unaligned_le16(len & 0x3FFF, skb_push(skb, 2));
376
377 /* add a zero-length EEM packet, if needed */
378 if (padlen)
379 put_unaligned_le16(0, skb_put(skb, 2));
380
381 return skb;
382}
383
384/*
385 * Remove the EEM header. Note that there can be many EEM packets in a single
386 * USB transfer, so we need to break them out and handle them independently.
387 */
388static int eem_unwrap(struct gether *port,
389 struct sk_buff *skb,
390 struct sk_buff_head *list)
391{
392 struct usb_composite_dev *cdev = port->func.config->cdev;
393 int status = 0;
394
395 do {
396 struct sk_buff *skb2;
397 u16 header;
398 u16 len = 0;
399
400 if (skb->len < EEM_HLEN) {
401 status = -EINVAL;
402 DBG(cdev, "invalid EEM header\n");
403 goto error;
404 }
405
406 /* remove the EEM header */
407 header = get_unaligned_le16(skb->data);
408 skb_pull(skb, EEM_HLEN);
409
410 /* EEM packet header format:
411 * b0..14: EEM type dependent (data or command)
412 * b15: bmType (0 == data, 1 == command)
413 */
414 if (header & BIT(15)) {
415 struct usb_request *req = cdev->req;
416 u16 bmEEMCmd;
417
418 /* EEM command packet format:
419 * b0..10: bmEEMCmdParam
420 * b11..13: bmEEMCmd
421 * b14: reserved (must be zero)
422 * b15: bmType (1 == command)
423 */
424 if (header & BIT(14))
425 continue;
426
427 bmEEMCmd = (header >> 11) & 0x7;
428 switch (bmEEMCmd) {
429 case 0: /* echo */
430 len = header & 0x7FF;
431 if (skb->len < len) {
432 status = -EOVERFLOW;
433 goto error;
434 }
435
436 skb2 = skb_clone(skb, GFP_ATOMIC);
437 if (unlikely(!skb2)) {
438 DBG(cdev, "EEM echo response error\n");
439 goto next;
440 }
441 skb_trim(skb2, len);
442 put_unaligned_le16(BIT(15) | BIT(11) | len,
443 skb_push(skb2, 2));
444 skb_copy_bits(skb2, 0, req->buf, skb2->len);
445 req->length = skb2->len;
446 req->complete = eem_cmd_complete;
447 req->zero = 1;
448 req->context = skb2;
449 if (usb_ep_queue(port->in_ep, req, GFP_ATOMIC))
450 DBG(cdev, "echo response queue fail\n");
451 break;
452
453 case 1: /* echo response */
454 case 2: /* suspend hint */
455 case 3: /* response hint */
456 case 4: /* response complete hint */
457 case 5: /* tickle */
458 default: /* reserved */
459 continue;
460 }
461 } else {
462 u32 crc, crc2;
463 struct sk_buff *skb3;
464
465 /* check for zero-length EEM packet */
466 if (header == 0)
467 continue;
468
469 /* EEM data packet format:
470 * b0..13: length of ethernet frame
471 * b14: bmCRC (0 == sentinel, 1 == calculated)
472 * b15: bmType (0 == data)
473 */
474 len = header & 0x3FFF;
475 if ((skb->len < len)
476 || (len < (ETH_HLEN + ETH_FCS_LEN))) {
477 status = -EINVAL;
478 goto error;
479 }
480
481 /* validate CRC */
482 if (header & BIT(14)) {
483 crc = get_unaligned_le32(skb->data + len
484 - ETH_FCS_LEN);
485 crc2 = ~crc32_le(~0,
486 skb->data, len - ETH_FCS_LEN);
487 } else {
488 crc = get_unaligned_be32(skb->data + len
489 - ETH_FCS_LEN);
490 crc2 = 0xdeadbeef;
491 }
492 if (crc != crc2) {
493 DBG(cdev, "invalid EEM CRC\n");
494 goto next;
495 }
496
497 skb2 = skb_clone(skb, GFP_ATOMIC);
498 if (unlikely(!skb2)) {
499 DBG(cdev, "unable to unframe EEM packet\n");
500 continue;
501 }
502 skb_trim(skb2, len - ETH_FCS_LEN);
503
504 skb3 = skb_copy_expand(skb2,
505 NET_IP_ALIGN,
506 0,
507 GFP_ATOMIC);
508 if (unlikely(!skb3)) {
509 dev_kfree_skb_any(skb2);
510 continue;
511 }
512 dev_kfree_skb_any(skb2);
513 skb_queue_tail(list, skb3);
514 }
515next:
516 skb_pull(skb, len);
517 } while (skb->len);
518
519error:
520 dev_kfree_skb_any(skb);
521 return status;
522}
523
524static inline struct f_eem_opts *to_f_eem_opts(struct config_item *item)
525{
526 return container_of(to_config_group(item), struct f_eem_opts,
527 func_inst.group);
528}
529
530/* f_eem_item_ops */
531USB_ETHERNET_CONFIGFS_ITEM(eem);
532
533/* f_eem_opts_dev_addr */
534USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(eem);
535
536/* f_eem_opts_host_addr */
537USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(eem);
538
539/* f_eem_opts_qmult */
540USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(eem);
541
542/* f_eem_opts_ifname */
543USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(eem);
544
545static struct configfs_attribute *eem_attrs[] = {
546 &eem_opts_attr_dev_addr,
547 &eem_opts_attr_host_addr,
548 &eem_opts_attr_qmult,
549 &eem_opts_attr_ifname,
550 NULL,
551};
552
553static const struct config_item_type eem_func_type = {
554 .ct_item_ops = &eem_item_ops,
555 .ct_attrs = eem_attrs,
556 .ct_owner = THIS_MODULE,
557};
558
559static void eem_free_inst(struct usb_function_instance *f)
560{
561 struct f_eem_opts *opts;
562
563 opts = container_of(f, struct f_eem_opts, func_inst);
564 if (opts->bound)
565 gether_cleanup(netdev_priv(opts->net));
566 else
567 free_netdev(opts->net);
568 kfree(opts);
569}
570
571static struct usb_function_instance *eem_alloc_inst(void)
572{
573 struct f_eem_opts *opts;
574
575 opts = kzalloc(sizeof(*opts), GFP_KERNEL);
576 if (!opts)
577 return ERR_PTR(-ENOMEM);
578 mutex_init(&opts->lock);
579 opts->func_inst.free_func_inst = eem_free_inst;
580 opts->net = gether_setup_default();
581 if (IS_ERR(opts->net)) {
582 struct net_device *net = opts->net;
583 kfree(opts);
584 return ERR_CAST(net);
585 }
586
587 config_group_init_type_name(&opts->func_inst.group, "", &eem_func_type);
588
589 return &opts->func_inst;
590}
591
592static void eem_free(struct usb_function *f)
593{
594 struct f_eem *eem;
595 struct f_eem_opts *opts;
596
597 eem = func_to_eem(f);
598 opts = container_of(f->fi, struct f_eem_opts, func_inst);
599 kfree(eem);
600 mutex_lock(&opts->lock);
601 opts->refcnt--;
602 mutex_unlock(&opts->lock);
603}
604
605static void eem_unbind(struct usb_configuration *c, struct usb_function *f)
606{
607 DBG(c->cdev, "eem unbind\n");
608
609 usb_free_all_descriptors(f);
610}
611
612static struct usb_function *eem_alloc(struct usb_function_instance *fi)
613{
614 struct f_eem *eem;
615 struct f_eem_opts *opts;
616
617 /* allocate and initialize one new instance */
618 eem = kzalloc(sizeof(*eem), GFP_KERNEL);
619 if (!eem)
620 return ERR_PTR(-ENOMEM);
621
622 opts = container_of(fi, struct f_eem_opts, func_inst);
623 mutex_lock(&opts->lock);
624 opts->refcnt++;
625
626 eem->port.ioport = netdev_priv(opts->net);
627 mutex_unlock(&opts->lock);
628 eem->port.cdc_filter = DEFAULT_FILTER;
629
630 eem->port.func.name = "cdc_eem";
631 /* descriptors are per-instance copies */
632 eem->port.func.bind = eem_bind;
633 eem->port.func.unbind = eem_unbind;
634 eem->port.func.set_alt = eem_set_alt;
635 eem->port.func.setup = eem_setup;
636 eem->port.func.disable = eem_disable;
637 eem->port.func.free_func = eem_free;
638 eem->port.wrap = eem_wrap;
639 eem->port.unwrap = eem_unwrap;
640 eem->port.header_len = EEM_HLEN;
641
642 return &eem->port.func;
643}
644
645DECLARE_USB_FUNCTION_INIT(eem, eem_alloc_inst, eem_alloc);
646MODULE_LICENSE("GPL");
647MODULE_AUTHOR("David Brownell");