1/*
2 * f_eem.c -- USB CDC Ethernet (EEM) link function driver
3 *
4 * Copyright (C) 2003-2005,2008 David Brownell
5 * Copyright (C) 2008 Nokia Corporation
6 * Copyright (C) 2009 EF Johnson Technologies
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 */
13
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/device.h>
17#include <linux/etherdevice.h>
18#include <linux/crc32.h>
19#include <linux/slab.h>
20
21#include "u_ether.h"
22#include "u_ether_configfs.h"
23#include "u_eem.h"
24
25#define EEM_HLEN 2
26
27/*
28 * This function is a "CDC Ethernet Emulation Model" (CDC EEM)
29 * Ethernet link.
30 */
31
32struct f_eem {
33	struct gether			port;
34	u8				ctrl_id;
35};
36
37static inline struct f_eem *func_to_eem(struct usb_function *f)
38{
39	return container_of(f, struct f_eem, port.func);
40}
41
42/*-------------------------------------------------------------------------*/
43
44/* interface descriptor: */
45
46static struct usb_interface_descriptor eem_intf = {
47	.bLength =		sizeof eem_intf,
48	.bDescriptorType =	USB_DT_INTERFACE,
49
50	/* .bInterfaceNumber = DYNAMIC */
51	.bNumEndpoints =	2,
52	.bInterfaceClass =	USB_CLASS_COMM,
53	.bInterfaceSubClass =	USB_CDC_SUBCLASS_EEM,
54	.bInterfaceProtocol =	USB_CDC_PROTO_EEM,
55	/* .iInterface = DYNAMIC */
56};
57
58/* full speed support: */
59
60static struct usb_endpoint_descriptor eem_fs_in_desc = {
61	.bLength =		USB_DT_ENDPOINT_SIZE,
62	.bDescriptorType =	USB_DT_ENDPOINT,
63
64	.bEndpointAddress =	USB_DIR_IN,
65	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
66};
67
68static struct usb_endpoint_descriptor eem_fs_out_desc = {
69	.bLength =		USB_DT_ENDPOINT_SIZE,
70	.bDescriptorType =	USB_DT_ENDPOINT,
71
72	.bEndpointAddress =	USB_DIR_OUT,
73	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
74};
75
76static struct usb_descriptor_header *eem_fs_function[] = {
77	/* CDC EEM control descriptors */
78	(struct usb_descriptor_header *) &eem_intf,
79	(struct usb_descriptor_header *) &eem_fs_in_desc,
80	(struct usb_descriptor_header *) &eem_fs_out_desc,
81	NULL,
82};
83
84/* high speed support: */
85
86static struct usb_endpoint_descriptor eem_hs_in_desc = {
87	.bLength =		USB_DT_ENDPOINT_SIZE,
88	.bDescriptorType =	USB_DT_ENDPOINT,
89
90	.bEndpointAddress =	USB_DIR_IN,
91	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
92	.wMaxPacketSize =	cpu_to_le16(512),
93};
94
95static struct usb_endpoint_descriptor eem_hs_out_desc = {
96	.bLength =		USB_DT_ENDPOINT_SIZE,
97	.bDescriptorType =	USB_DT_ENDPOINT,
98
99	.bEndpointAddress =	USB_DIR_OUT,
100	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
101	.wMaxPacketSize =	cpu_to_le16(512),
102};
103
104static struct usb_descriptor_header *eem_hs_function[] = {
105	/* CDC EEM control descriptors */
106	(struct usb_descriptor_header *) &eem_intf,
107	(struct usb_descriptor_header *) &eem_hs_in_desc,
108	(struct usb_descriptor_header *) &eem_hs_out_desc,
109	NULL,
110};
111
112/* super speed support: */
113
114static struct usb_endpoint_descriptor eem_ss_in_desc = {
115	.bLength =		USB_DT_ENDPOINT_SIZE,
116	.bDescriptorType =	USB_DT_ENDPOINT,
117
118	.bEndpointAddress =	USB_DIR_IN,
119	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
120	.wMaxPacketSize =	cpu_to_le16(1024),
121};
122
123static struct usb_endpoint_descriptor eem_ss_out_desc = {
124	.bLength =		USB_DT_ENDPOINT_SIZE,
125	.bDescriptorType =	USB_DT_ENDPOINT,
126
127	.bEndpointAddress =	USB_DIR_OUT,
128	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
129	.wMaxPacketSize =	cpu_to_le16(1024),
130};
131
132static struct usb_ss_ep_comp_descriptor eem_ss_bulk_comp_desc = {
133	.bLength =		sizeof eem_ss_bulk_comp_desc,
134	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,
135
136	/* the following 2 values can be tweaked if necessary */
137	/* .bMaxBurst =		0, */
138	/* .bmAttributes =	0, */
139};
140
141static struct usb_descriptor_header *eem_ss_function[] = {
142	/* CDC EEM control descriptors */
143	(struct usb_descriptor_header *) &eem_intf,
144	(struct usb_descriptor_header *) &eem_ss_in_desc,
145	(struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
146	(struct usb_descriptor_header *) &eem_ss_out_desc,
147	(struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
148	NULL,
149};
150
151/* string descriptors: */
152
153static struct usb_string eem_string_defs[] = {
154	[0].s = "CDC Ethernet Emulation Model (EEM)",
155	{  } /* end of list */
156};
157
158static struct usb_gadget_strings eem_string_table = {
159	.language =		0x0409,	/* en-us */
160	.strings =		eem_string_defs,
161};
162
163static struct usb_gadget_strings *eem_strings[] = {
164	&eem_string_table,
165	NULL,
166};
167
168/*-------------------------------------------------------------------------*/
169
170static int eem_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
171{
172	struct usb_composite_dev *cdev = f->config->cdev;
173	int			value = -EOPNOTSUPP;
174	u16			w_index = le16_to_cpu(ctrl->wIndex);
175	u16			w_value = le16_to_cpu(ctrl->wValue);
176	u16			w_length = le16_to_cpu(ctrl->wLength);
177
178	DBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
179		ctrl->bRequestType, ctrl->bRequest,
180		w_value, w_index, w_length);
181
182	/* device either stalls (value < 0) or reports success */
183	return value;
184}
185
186
187static int eem_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
188{
189	struct f_eem		*eem = func_to_eem(f);
190	struct usb_composite_dev *cdev = f->config->cdev;
191	struct net_device	*net;
192
193	/* we know alt == 0, so this is an activation or a reset */
194	if (alt != 0)
195		goto fail;
196
197	if (intf == eem->ctrl_id) {
198		DBG(cdev, "reset eem\n");
199		gether_disconnect(&eem->port);
200
201		if (!eem->port.in_ep->desc || !eem->port.out_ep->desc) {
202			DBG(cdev, "init eem\n");
203			if (config_ep_by_speed(cdev->gadget, f,
204					       eem->port.in_ep) ||
205			    config_ep_by_speed(cdev->gadget, f,
206					       eem->port.out_ep)) {
207				eem->port.in_ep->desc = NULL;
208				eem->port.out_ep->desc = NULL;
209				goto fail;
210			}
211		}
212
213		/* zlps should not occur because zero-length EEM packets
214		 * will be inserted in those cases where they would occur
215		 */
216		eem->port.is_zlp_ok = 1;
217		eem->port.cdc_filter = DEFAULT_FILTER;
218		DBG(cdev, "activate eem\n");
219		net = gether_connect(&eem->port);
220		if (IS_ERR(net))
221			return PTR_ERR(net);
222	} else
223		goto fail;
224
225	return 0;
226fail:
227	return -EINVAL;
228}
229
230static void eem_disable(struct usb_function *f)
231{
232	struct f_eem		*eem = func_to_eem(f);
233	struct usb_composite_dev *cdev = f->config->cdev;
234
235	DBG(cdev, "eem deactivated\n");
236
237	if (eem->port.in_ep->enabled)
238		gether_disconnect(&eem->port);
239}
240
241/*-------------------------------------------------------------------------*/
242
243/* EEM function driver setup/binding */
244
245static int eem_bind(struct usb_configuration *c, struct usb_function *f)
246{
247	struct usb_composite_dev *cdev = c->cdev;
248	struct f_eem		*eem = func_to_eem(f);
249	struct usb_string	*us;
250	int			status;
251	struct usb_ep		*ep;
252
253	struct f_eem_opts	*eem_opts;
254
255	eem_opts = container_of(f->fi, struct f_eem_opts, func_inst);
256	/*
257	 * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
258	 * configurations are bound in sequence with list_for_each_entry,
259	 * in each configuration its functions are bound in sequence
260	 * with list_for_each_entry, so we assume no race condition
261	 * with regard to eem_opts->bound access
262	 */
263	if (!eem_opts->bound) {
264		mutex_lock(&eem_opts->lock);
265		gether_set_gadget(eem_opts->net, cdev->gadget);
266		status = gether_register_netdev(eem_opts->net);
267		mutex_unlock(&eem_opts->lock);
268		if (status)
269			return status;
270		eem_opts->bound = true;
271	}
272
273	us = usb_gstrings_attach(cdev, eem_strings,
274				 ARRAY_SIZE(eem_string_defs));
275	if (IS_ERR(us))
276		return PTR_ERR(us);
277	eem_intf.iInterface = us[0].id;
278
279	/* allocate instance-specific interface IDs */
280	status = usb_interface_id(c, f);
281	if (status < 0)
282		goto fail;
283	eem->ctrl_id = status;
284	eem_intf.bInterfaceNumber = status;
285
286	status = -ENODEV;
287
288	/* allocate instance-specific endpoints */
289	ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_in_desc);
290	if (!ep)
291		goto fail;
292	eem->port.in_ep = ep;
293
294	ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_out_desc);
295	if (!ep)
296		goto fail;
297	eem->port.out_ep = ep;
298
299	status = -ENOMEM;
300
301	/* support all relevant hardware speeds... we expect that when
302	 * hardware is dual speed, all bulk-capable endpoints work at
303	 * both speeds
304	 */
305	eem_hs_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
306	eem_hs_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
307
308	eem_ss_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
309	eem_ss_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
310
311	status = usb_assign_descriptors(f, eem_fs_function, eem_hs_function,
312			eem_ss_function);
313	if (status)
314		goto fail;
315
316	DBG(cdev, "CDC Ethernet (EEM): %s speed IN/%s OUT/%s\n",
317			gadget_is_superspeed(c->cdev->gadget) ? "super" :
318			gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
319			eem->port.in_ep->name, eem->port.out_ep->name);
320	return 0;
321
322fail:
323	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
324
325	return status;
326}
327
328static void eem_cmd_complete(struct usb_ep *ep, struct usb_request *req)
329{
330	struct sk_buff *skb = (struct sk_buff *)req->context;
331
332	dev_kfree_skb_any(skb);
333}
334
335/*
336 * Add the EEM header and ethernet checksum.
337 * We currently do not attempt to put multiple ethernet frames
338 * into a single USB transfer
339 */
340static struct sk_buff *eem_wrap(struct gether *port, struct sk_buff *skb)
341{
342	struct sk_buff	*skb2 = NULL;
343	struct usb_ep	*in = port->in_ep;
344	int		padlen = 0;
345	u16		len = skb->len;
346
347	int headroom = skb_headroom(skb);
348	int tailroom = skb_tailroom(skb);
349
350	/* When (len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) is 0,
351	 * stick two bytes of zero-length EEM packet on the end.
352	 */
353	if (((len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) == 0)
354		padlen += 2;
355
356	if ((tailroom >= (ETH_FCS_LEN + padlen)) &&
357			(headroom >= EEM_HLEN) && !skb_cloned(skb))
358		goto done;
359
360	skb2 = skb_copy_expand(skb, EEM_HLEN, ETH_FCS_LEN + padlen, GFP_ATOMIC);
361	dev_kfree_skb_any(skb);
362	skb = skb2;
363	if (!skb)
364		return skb;
365
366done:
367	/* use the "no CRC" option */
368	put_unaligned_be32(0xdeadbeef, skb_put(skb, 4));
369
370	/* EEM packet header format:
371	 * b0..13:	length of ethernet frame
372	 * b14:		bmCRC (0 == sentinel CRC)
373	 * b15:		bmType (0 == data)
374	 */
375	len = skb->len;
376	put_unaligned_le16(len & 0x3FFF, skb_push(skb, 2));
377
378	/* add a zero-length EEM packet, if needed */
379	if (padlen)
380		put_unaligned_le16(0, skb_put(skb, 2));
381
382	return skb;
383}
384
385/*
386 * Remove the EEM header.  Note that there can be many EEM packets in a single
387 * USB transfer, so we need to break them out and handle them independently.
388 */
389static int eem_unwrap(struct gether *port,
390			struct sk_buff *skb,
391			struct sk_buff_head *list)
392{
393	struct usb_composite_dev	*cdev = port->func.config->cdev;
394	int				status = 0;
395
396	do {
397		struct sk_buff	*skb2;
398		u16		header;
399		u16		len = 0;
400
401		if (skb->len < EEM_HLEN) {
402			status = -EINVAL;
403			DBG(cdev, "invalid EEM header\n");
404			goto error;
405		}
406
407		/* remove the EEM header */
408		header = get_unaligned_le16(skb->data);
409		skb_pull(skb, EEM_HLEN);
410
411		/* EEM packet header format:
412		 * b0..14:	EEM type dependent (data or command)
413		 * b15:		bmType (0 == data, 1 == command)
414		 */
415		if (header & BIT(15)) {
416			struct usb_request	*req = cdev->req;
417			u16			bmEEMCmd;
418
419			/* EEM command packet format:
420			 * b0..10:	bmEEMCmdParam
421			 * b11..13:	bmEEMCmd
422			 * b14:		reserved (must be zero)
423			 * b15:		bmType (1 == command)
424			 */
425			if (header & BIT(14))
426				continue;
427
428			bmEEMCmd = (header >> 11) & 0x7;
429			switch (bmEEMCmd) {
430			case 0: /* echo */
431				len = header & 0x7FF;
432				if (skb->len < len) {
433					status = -EOVERFLOW;
434					goto error;
435				}
436
437				skb2 = skb_clone(skb, GFP_ATOMIC);
438				if (unlikely(!skb2)) {
439					DBG(cdev, "EEM echo response error\n");
440					goto next;
441				}
442				skb_trim(skb2, len);
443				put_unaligned_le16(BIT(15) | BIT(11) | len,
444							skb_push(skb2, 2));
445				skb_copy_bits(skb2, 0, req->buf, skb2->len);
446				req->length = skb2->len;
447				req->complete = eem_cmd_complete;
448				req->zero = 1;
449				req->context = skb2;
450				if (usb_ep_queue(port->in_ep, req, GFP_ATOMIC))
451					DBG(cdev, "echo response queue fail\n");
452				break;
453
454			case 1:  /* echo response */
455			case 2:  /* suspend hint */
456			case 3:  /* response hint */
457			case 4:  /* response complete hint */
458			case 5:  /* tickle */
459			default: /* reserved */
460				continue;
461			}
462		} else {
463			u32		crc, crc2;
464			struct sk_buff	*skb3;
465
466			/* check for zero-length EEM packet */
467			if (header == 0)
468				continue;
469
470			/* EEM data packet format:
471			 * b0..13:	length of ethernet frame
472			 * b14:		bmCRC (0 == sentinel, 1 == calculated)
473			 * b15:		bmType (0 == data)
474			 */
475			len = header & 0x3FFF;
476			if ((skb->len < len)
477					|| (len < (ETH_HLEN + ETH_FCS_LEN))) {
478				status = -EINVAL;
479				goto error;
480			}
481
482			/* validate CRC */
483			if (header & BIT(14)) {
484				crc = get_unaligned_le32(skb->data + len
485							- ETH_FCS_LEN);
486				crc2 = ~crc32_le(~0,
487						skb->data, len - ETH_FCS_LEN);
488			} else {
489				crc = get_unaligned_be32(skb->data + len
490							- ETH_FCS_LEN);
491				crc2 = 0xdeadbeef;
492			}
493			if (crc != crc2) {
494				DBG(cdev, "invalid EEM CRC\n");
495				goto next;
496			}
497
498			skb2 = skb_clone(skb, GFP_ATOMIC);
499			if (unlikely(!skb2)) {
500				DBG(cdev, "unable to unframe EEM packet\n");
501				continue;
502			}
503			skb_trim(skb2, len - ETH_FCS_LEN);
504
505			skb3 = skb_copy_expand(skb2,
506						NET_IP_ALIGN,
507						0,
508						GFP_ATOMIC);
509			if (unlikely(!skb3)) {
510				DBG(cdev, "unable to realign EEM packet\n");
511				dev_kfree_skb_any(skb2);
512				continue;
513			}
514			dev_kfree_skb_any(skb2);
515			skb_queue_tail(list, skb3);
516		}
517next:
518		skb_pull(skb, len);
519	} while (skb->len);
520
521error:
522	dev_kfree_skb_any(skb);
523	return status;
524}
525
526static inline struct f_eem_opts *to_f_eem_opts(struct config_item *item)
527{
528	return container_of(to_config_group(item), struct f_eem_opts,
529			    func_inst.group);
530}
531
532/* f_eem_item_ops */
533USB_ETHERNET_CONFIGFS_ITEM(eem);
534
535/* f_eem_opts_dev_addr */
536USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(eem);
537
538/* f_eem_opts_host_addr */
539USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(eem);
540
541/* f_eem_opts_qmult */
542USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(eem);
543
544/* f_eem_opts_ifname */
545USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(eem);
546
547static struct configfs_attribute *eem_attrs[] = {
548	&eem_opts_attr_dev_addr,
549	&eem_opts_attr_host_addr,
550	&eem_opts_attr_qmult,
551	&eem_opts_attr_ifname,
552	NULL,
553};
554
555static struct config_item_type eem_func_type = {
556	.ct_item_ops	= &eem_item_ops,
557	.ct_attrs	= eem_attrs,
558	.ct_owner	= THIS_MODULE,
559};
560
561static void eem_free_inst(struct usb_function_instance *f)
562{
563	struct f_eem_opts *opts;
564
565	opts = container_of(f, struct f_eem_opts, func_inst);
566	if (opts->bound)
567		gether_cleanup(netdev_priv(opts->net));
568	else
569		free_netdev(opts->net);
570	kfree(opts);
571}
572
573static struct usb_function_instance *eem_alloc_inst(void)
574{
575	struct f_eem_opts *opts;
576
577	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
578	if (!opts)
579		return ERR_PTR(-ENOMEM);
580	mutex_init(&opts->lock);
581	opts->func_inst.free_func_inst = eem_free_inst;
582	opts->net = gether_setup_default();
583	if (IS_ERR(opts->net)) {
584		struct net_device *net = opts->net;
585		kfree(opts);
586		return ERR_CAST(net);
587	}
588
589	config_group_init_type_name(&opts->func_inst.group, "", &eem_func_type);
590
591	return &opts->func_inst;
592}
593
594static void eem_free(struct usb_function *f)
595{
596	struct f_eem *eem;
597	struct f_eem_opts *opts;
598
599	eem = func_to_eem(f);
600	opts = container_of(f->fi, struct f_eem_opts, func_inst);
601	kfree(eem);
602	mutex_lock(&opts->lock);
603	opts->refcnt--;
604	mutex_unlock(&opts->lock);
605}
606
607static void eem_unbind(struct usb_configuration *c, struct usb_function *f)
608{
609	DBG(c->cdev, "eem unbind\n");
610
611	usb_free_all_descriptors(f);
612}
613
614static struct usb_function *eem_alloc(struct usb_function_instance *fi)
615{
616	struct f_eem	*eem;
617	struct f_eem_opts *opts;
618
619	/* allocate and initialize one new instance */
620	eem = kzalloc(sizeof(*eem), GFP_KERNEL);
621	if (!eem)
622		return ERR_PTR(-ENOMEM);
623
624	opts = container_of(fi, struct f_eem_opts, func_inst);
625	mutex_lock(&opts->lock);
626	opts->refcnt++;
627
628	eem->port.ioport = netdev_priv(opts->net);
629	mutex_unlock(&opts->lock);
630	eem->port.cdc_filter = DEFAULT_FILTER;
631
632	eem->port.func.name = "cdc_eem";
633	/* descriptors are per-instance copies */
634	eem->port.func.bind = eem_bind;
635	eem->port.func.unbind = eem_unbind;
636	eem->port.func.set_alt = eem_set_alt;
637	eem->port.func.setup = eem_setup;
638	eem->port.func.disable = eem_disable;
639	eem->port.func.free_func = eem_free;
640	eem->port.wrap = eem_wrap;
641	eem->port.unwrap = eem_unwrap;
642	eem->port.header_len = EEM_HLEN;
643
644	return &eem->port.func;
645}
646
647DECLARE_USB_FUNCTION_INIT(eem, eem_alloc_inst, eem_alloc);
648MODULE_LICENSE("GPL");
649MODULE_AUTHOR("David Brownell");
650