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
199		if (eem->port.in_ep->driver_data) {
200			DBG(cdev, "reset eem\n");
201			gether_disconnect(&eem->port);
202		}
203
204		if (!eem->port.in_ep->desc || !eem->port.out_ep->desc) {
205			DBG(cdev, "init eem\n");
206			if (config_ep_by_speed(cdev->gadget, f,
207					       eem->port.in_ep) ||
208			    config_ep_by_speed(cdev->gadget, f,
209					       eem->port.out_ep)) {
210				eem->port.in_ep->desc = NULL;
211				eem->port.out_ep->desc = NULL;
212				goto fail;
213			}
214		}
215
216		/* zlps should not occur because zero-length EEM packets
217		 * will be inserted in those cases where they would occur
218		 */
219		eem->port.is_zlp_ok = 1;
220		eem->port.cdc_filter = DEFAULT_FILTER;
221		DBG(cdev, "activate eem\n");
222		net = gether_connect(&eem->port);
223		if (IS_ERR(net))
224			return PTR_ERR(net);
225	} else
226		goto fail;
227
228	return 0;
229fail:
230	return -EINVAL;
231}
232
233static void eem_disable(struct usb_function *f)
234{
235	struct f_eem		*eem = func_to_eem(f);
236	struct usb_composite_dev *cdev = f->config->cdev;
237
238	DBG(cdev, "eem deactivated\n");
239
240	if (eem->port.in_ep->driver_data)
241		gether_disconnect(&eem->port);
242}
243
244/*-------------------------------------------------------------------------*/
245
246/* EEM function driver setup/binding */
247
248static int eem_bind(struct usb_configuration *c, struct usb_function *f)
249{
250	struct usb_composite_dev *cdev = c->cdev;
251	struct f_eem		*eem = func_to_eem(f);
252	struct usb_string	*us;
253	int			status;
254	struct usb_ep		*ep;
255
256	struct f_eem_opts	*eem_opts;
257
258	eem_opts = container_of(f->fi, struct f_eem_opts, func_inst);
259	/*
260	 * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
261	 * configurations are bound in sequence with list_for_each_entry,
262	 * in each configuration its functions are bound in sequence
263	 * with list_for_each_entry, so we assume no race condition
264	 * with regard to eem_opts->bound access
265	 */
266	if (!eem_opts->bound) {
267		mutex_lock(&eem_opts->lock);
268		gether_set_gadget(eem_opts->net, cdev->gadget);
269		status = gether_register_netdev(eem_opts->net);
270		mutex_unlock(&eem_opts->lock);
271		if (status)
272			return status;
273		eem_opts->bound = true;
274	}
275
276	us = usb_gstrings_attach(cdev, eem_strings,
277				 ARRAY_SIZE(eem_string_defs));
278	if (IS_ERR(us))
279		return PTR_ERR(us);
280	eem_intf.iInterface = us[0].id;
281
282	/* allocate instance-specific interface IDs */
283	status = usb_interface_id(c, f);
284	if (status < 0)
285		goto fail;
286	eem->ctrl_id = status;
287	eem_intf.bInterfaceNumber = status;
288
289	status = -ENODEV;
290
291	/* allocate instance-specific endpoints */
292	ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_in_desc);
293	if (!ep)
294		goto fail;
295	eem->port.in_ep = ep;
296	ep->driver_data = cdev;	/* claim */
297
298	ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_out_desc);
299	if (!ep)
300		goto fail;
301	eem->port.out_ep = ep;
302	ep->driver_data = cdev;	/* claim */
303
304	status = -ENOMEM;
305
306	/* support all relevant hardware speeds... we expect that when
307	 * hardware is dual speed, all bulk-capable endpoints work at
308	 * both speeds
309	 */
310	eem_hs_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
311	eem_hs_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
312
313	eem_ss_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
314	eem_ss_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
315
316	status = usb_assign_descriptors(f, eem_fs_function, eem_hs_function,
317			eem_ss_function);
318	if (status)
319		goto fail;
320
321	DBG(cdev, "CDC Ethernet (EEM): %s speed IN/%s OUT/%s\n",
322			gadget_is_superspeed(c->cdev->gadget) ? "super" :
323			gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
324			eem->port.in_ep->name, eem->port.out_ep->name);
325	return 0;
326
327fail:
328	if (eem->port.out_ep)
329		eem->port.out_ep->driver_data = NULL;
330	if (eem->port.in_ep)
331		eem->port.in_ep->driver_data = NULL;
332
333	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
334
335	return status;
336}
337
338static void eem_cmd_complete(struct usb_ep *ep, struct usb_request *req)
339{
340	struct sk_buff *skb = (struct sk_buff *)req->context;
341
342	dev_kfree_skb_any(skb);
343}
344
345/*
346 * Add the EEM header and ethernet checksum.
347 * We currently do not attempt to put multiple ethernet frames
348 * into a single USB transfer
349 */
350static struct sk_buff *eem_wrap(struct gether *port, struct sk_buff *skb)
351{
352	struct sk_buff	*skb2 = NULL;
353	struct usb_ep	*in = port->in_ep;
354	int		padlen = 0;
355	u16		len = skb->len;
356
357	int headroom = skb_headroom(skb);
358	int tailroom = skb_tailroom(skb);
359
360	/* When (len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) is 0,
361	 * stick two bytes of zero-length EEM packet on the end.
362	 */
363	if (((len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) == 0)
364		padlen += 2;
365
366	if ((tailroom >= (ETH_FCS_LEN + padlen)) &&
367			(headroom >= EEM_HLEN) && !skb_cloned(skb))
368		goto done;
369
370	skb2 = skb_copy_expand(skb, EEM_HLEN, ETH_FCS_LEN + padlen, GFP_ATOMIC);
371	dev_kfree_skb_any(skb);
372	skb = skb2;
373	if (!skb)
374		return skb;
375
376done:
377	/* use the "no CRC" option */
378	put_unaligned_be32(0xdeadbeef, skb_put(skb, 4));
379
380	/* EEM packet header format:
381	 * b0..13:	length of ethernet frame
382	 * b14:		bmCRC (0 == sentinel CRC)
383	 * b15:		bmType (0 == data)
384	 */
385	len = skb->len;
386	put_unaligned_le16(len & 0x3FFF, skb_push(skb, 2));
387
388	/* add a zero-length EEM packet, if needed */
389	if (padlen)
390		put_unaligned_le16(0, skb_put(skb, 2));
391
392	return skb;
393}
394
395/*
396 * Remove the EEM header.  Note that there can be many EEM packets in a single
397 * USB transfer, so we need to break them out and handle them independently.
398 */
399static int eem_unwrap(struct gether *port,
400			struct sk_buff *skb,
401			struct sk_buff_head *list)
402{
403	struct usb_composite_dev	*cdev = port->func.config->cdev;
404	int				status = 0;
405
406	do {
407		struct sk_buff	*skb2;
408		u16		header;
409		u16		len = 0;
410
411		if (skb->len < EEM_HLEN) {
412			status = -EINVAL;
413			DBG(cdev, "invalid EEM header\n");
414			goto error;
415		}
416
417		/* remove the EEM header */
418		header = get_unaligned_le16(skb->data);
419		skb_pull(skb, EEM_HLEN);
420
421		/* EEM packet header format:
422		 * b0..14:	EEM type dependent (data or command)
423		 * b15:		bmType (0 == data, 1 == command)
424		 */
425		if (header & BIT(15)) {
426			struct usb_request	*req = cdev->req;
427			u16			bmEEMCmd;
428
429			/* EEM command packet format:
430			 * b0..10:	bmEEMCmdParam
431			 * b11..13:	bmEEMCmd
432			 * b14:		reserved (must be zero)
433			 * b15:		bmType (1 == command)
434			 */
435			if (header & BIT(14))
436				continue;
437
438			bmEEMCmd = (header >> 11) & 0x7;
439			switch (bmEEMCmd) {
440			case 0: /* echo */
441				len = header & 0x7FF;
442				if (skb->len < len) {
443					status = -EOVERFLOW;
444					goto error;
445				}
446
447				skb2 = skb_clone(skb, GFP_ATOMIC);
448				if (unlikely(!skb2)) {
449					DBG(cdev, "EEM echo response error\n");
450					goto next;
451				}
452				skb_trim(skb2, len);
453				put_unaligned_le16(BIT(15) | BIT(11) | len,
454							skb_push(skb2, 2));
455				skb_copy_bits(skb2, 0, req->buf, skb2->len);
456				req->length = skb2->len;
457				req->complete = eem_cmd_complete;
458				req->zero = 1;
459				req->context = skb2;
460				if (usb_ep_queue(port->in_ep, req, GFP_ATOMIC))
461					DBG(cdev, "echo response queue fail\n");
462				break;
463
464			case 1:  /* echo response */
465			case 2:  /* suspend hint */
466			case 3:  /* response hint */
467			case 4:  /* response complete hint */
468			case 5:  /* tickle */
469			default: /* reserved */
470				continue;
471			}
472		} else {
473			u32		crc, crc2;
474			struct sk_buff	*skb3;
475
476			/* check for zero-length EEM packet */
477			if (header == 0)
478				continue;
479
480			/* EEM data packet format:
481			 * b0..13:	length of ethernet frame
482			 * b14:		bmCRC (0 == sentinel, 1 == calculated)
483			 * b15:		bmType (0 == data)
484			 */
485			len = header & 0x3FFF;
486			if ((skb->len < len)
487					|| (len < (ETH_HLEN + ETH_FCS_LEN))) {
488				status = -EINVAL;
489				goto error;
490			}
491
492			/* validate CRC */
493			if (header & BIT(14)) {
494				crc = get_unaligned_le32(skb->data + len
495							- ETH_FCS_LEN);
496				crc2 = ~crc32_le(~0,
497						skb->data, len - ETH_FCS_LEN);
498			} else {
499				crc = get_unaligned_be32(skb->data + len
500							- ETH_FCS_LEN);
501				crc2 = 0xdeadbeef;
502			}
503			if (crc != crc2) {
504				DBG(cdev, "invalid EEM CRC\n");
505				goto next;
506			}
507
508			skb2 = skb_clone(skb, GFP_ATOMIC);
509			if (unlikely(!skb2)) {
510				DBG(cdev, "unable to unframe EEM packet\n");
511				continue;
512			}
513			skb_trim(skb2, len - ETH_FCS_LEN);
514
515			skb3 = skb_copy_expand(skb2,
516						NET_IP_ALIGN,
517						0,
518						GFP_ATOMIC);
519			if (unlikely(!skb3)) {
520				DBG(cdev, "unable to realign EEM packet\n");
521				dev_kfree_skb_any(skb2);
522				continue;
523			}
524			dev_kfree_skb_any(skb2);
525			skb_queue_tail(list, skb3);
526		}
527next:
528		skb_pull(skb, len);
529	} while (skb->len);
530
531error:
532	dev_kfree_skb_any(skb);
533	return status;
534}
535
536static inline struct f_eem_opts *to_f_eem_opts(struct config_item *item)
537{
538	return container_of(to_config_group(item), struct f_eem_opts,
539			    func_inst.group);
540}
541
542/* f_eem_item_ops */
543USB_ETHERNET_CONFIGFS_ITEM(eem);
544
545/* f_eem_opts_dev_addr */
546USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(eem);
547
548/* f_eem_opts_host_addr */
549USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(eem);
550
551/* f_eem_opts_qmult */
552USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(eem);
553
554/* f_eem_opts_ifname */
555USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(eem);
556
557static struct configfs_attribute *eem_attrs[] = {
558	&f_eem_opts_dev_addr.attr,
559	&f_eem_opts_host_addr.attr,
560	&f_eem_opts_qmult.attr,
561	&f_eem_opts_ifname.attr,
562	NULL,
563};
564
565static struct config_item_type eem_func_type = {
566	.ct_item_ops	= &eem_item_ops,
567	.ct_attrs	= eem_attrs,
568	.ct_owner	= THIS_MODULE,
569};
570
571static void eem_free_inst(struct usb_function_instance *f)
572{
573	struct f_eem_opts *opts;
574
575	opts = container_of(f, struct f_eem_opts, func_inst);
576	if (opts->bound)
577		gether_cleanup(netdev_priv(opts->net));
578	else
579		free_netdev(opts->net);
580	kfree(opts);
581}
582
583static struct usb_function_instance *eem_alloc_inst(void)
584{
585	struct f_eem_opts *opts;
586
587	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
588	if (!opts)
589		return ERR_PTR(-ENOMEM);
590	mutex_init(&opts->lock);
591	opts->func_inst.free_func_inst = eem_free_inst;
592	opts->net = gether_setup_default();
593	if (IS_ERR(opts->net)) {
594		struct net_device *net = opts->net;
595		kfree(opts);
596		return ERR_CAST(net);
597	}
598
599	config_group_init_type_name(&opts->func_inst.group, "", &eem_func_type);
600
601	return &opts->func_inst;
602}
603
604static void eem_free(struct usb_function *f)
605{
606	struct f_eem *eem;
607	struct f_eem_opts *opts;
608
609	eem = func_to_eem(f);
610	opts = container_of(f->fi, struct f_eem_opts, func_inst);
611	kfree(eem);
612	mutex_lock(&opts->lock);
613	opts->refcnt--;
614	mutex_unlock(&opts->lock);
615}
616
617static void eem_unbind(struct usb_configuration *c, struct usb_function *f)
618{
619	DBG(c->cdev, "eem unbind\n");
620
621	usb_free_all_descriptors(f);
622}
623
624static struct usb_function *eem_alloc(struct usb_function_instance *fi)
625{
626	struct f_eem	*eem;
627	struct f_eem_opts *opts;
628
629	/* allocate and initialize one new instance */
630	eem = kzalloc(sizeof(*eem), GFP_KERNEL);
631	if (!eem)
632		return ERR_PTR(-ENOMEM);
633
634	opts = container_of(fi, struct f_eem_opts, func_inst);
635	mutex_lock(&opts->lock);
636	opts->refcnt++;
637
638	eem->port.ioport = netdev_priv(opts->net);
639	mutex_unlock(&opts->lock);
640	eem->port.cdc_filter = DEFAULT_FILTER;
641
642	eem->port.func.name = "cdc_eem";
643	/* descriptors are per-instance copies */
644	eem->port.func.bind = eem_bind;
645	eem->port.func.unbind = eem_unbind;
646	eem->port.func.set_alt = eem_set_alt;
647	eem->port.func.setup = eem_setup;
648	eem->port.func.disable = eem_disable;
649	eem->port.func.free_func = eem_free;
650	eem->port.wrap = eem_wrap;
651	eem->port.unwrap = eem_unwrap;
652	eem->port.header_len = EEM_HLEN;
653
654	return &eem->port.func;
655}
656
657DECLARE_USB_FUNCTION_INIT(eem, eem_alloc_inst, eem_alloc);
658MODULE_LICENSE("GPL");
659MODULE_AUTHOR("David Brownell");
660