summaryrefslogtreecommitdiffstats
path: root/drivers/net/usb/lg-vl600.c
blob: 1d83ccfd72778ea2e2e0ca27f1c490d8eb18c5ca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
/*
 * Ethernet interface part of the LG VL600 LTE modem (4G dongle)
 *
 * Copyright (C) 2011 Intel Corporation
 * Author: Andrzej Zaborowski <balrogg@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/mii.h>
#include <linux/usb.h>
#include <linux/usb/cdc.h>
#include <linux/usb/usbnet.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <linux/inetdevice.h>

/*
 * The device has a CDC ACM port for modem control (it claims to be
 * CDC ACM anyway) and a CDC Ethernet port for actual network data.
 * It will however ignore data on both ports that is not encapsulated
 * in a specific way, any data returned is also encapsulated the same
 * way.  The headers don't seem to follow any popular standard.
 *
 * This driver adds and strips these headers from the ethernet frames
 * sent/received from the CDC Ethernet port.  The proprietary header
 * replaces the standard ethernet header in a packet so only actual
 * ethernet frames are allowed.  The headers allow some form of
 * multiplexing by using non standard values of the .h_proto field.
 * Windows/Mac drivers do send a couple of such frames to the device
 * during initialisation, with protocol set to 0x0906 or 0x0b06 and (what
 * seems to be) a flag in the .dummy_flags.  This doesn't seem necessary
 * for modem operation but can possibly be used for GPS or other funcitons.
 */

struct vl600_frame_hdr {
	__le32 len;
	__le32 serial;
	__le32 pkt_cnt;
	__le32 dummy_flags;
	__le32 dummy;
	__le32 magic;
} __attribute__((packed));

struct vl600_pkt_hdr {
	__le32 dummy[2];
	__le32 len;
	__be16 h_proto;
} __attribute__((packed));

struct vl600_state {
	struct sk_buff *current_rx_buf;
};

static int vl600_bind(struct usbnet *dev, struct usb_interface *intf)
{
	int ret;
	struct vl600_state *s = kzalloc(sizeof(struct vl600_state), GFP_KERNEL);

	if (!s)
		return -ENOMEM;

	ret = usbnet_cdc_bind(dev, intf);
	if (ret) {
		kfree(s);
		return ret;
	}

	dev->driver_priv = s;

	/* ARP packets don't go through, but they're also of no use.  The
	 * subnet has only two hosts anyway: us and the gateway / DHCP
	 * server (probably simulated by modem firmware or network operator)
	 * whose address changes everytime we connect to the intarwebz and
	 * who doesn't bother answering ARP requests either.  So hardware
	 * addresses have no meaning, the destination and the source of every
	 * packet depend only on whether it is on the IN or OUT endpoint.  */
	dev->net->flags |= IFF_NOARP;

	return ret;
}

static void vl600_unbind(struct usbnet *dev, struct usb_interface *intf)
{
	struct vl600_state *s = dev->driver_priv;

	if (s->current_rx_buf)
		dev_kfree_skb(s->current_rx_buf);

	kfree(s);

	return usbnet_cdc_unbind(dev, intf);
}

static int vl600_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
	struct vl600_frame_hdr *frame;
	struct vl600_pkt_hdr *packet;
	struct ethhdr *ethhdr;
	int packet_len, count;
	struct sk_buff *buf = skb;
	struct sk_buff *clone;
	struct vl600_state *s = dev->driver_priv;

	/* Frame lengths are generally 4B multiplies but every couple of
	 * hours there's an odd number of bytes sized yet correct frame,
	 * so don't require this.  */

	/* Allow a packet (or multiple packets batched together) to be
	 * split across many frames.  We don't allow a new batch to
	 * begin in the same frame another one is ending however, and no
	 * leading or trailing pad bytes.  */
	if (s->current_rx_buf) {
		frame = (struct vl600_frame_hdr *) s->current_rx_buf->data;
		if (skb->len + s->current_rx_buf->len >
				le32_to_cpup(&frame->len)) {
			netif_err(dev, ifup, dev->net, "Fragment too long\n");
			dev->net->stats.rx_length_errors++;
			goto error;
		}

		buf = s->current_rx_buf;
		memcpy(skb_put(buf, skb->len), skb->data, skb->len);
	} else if (skb->len < 4) {
		netif_err(dev, ifup, dev->net, "Frame too short\n");
		dev->net->stats.rx_length_errors++;
		goto error;
	}

	frame = (struct vl600_frame_hdr *) buf->data;
	/* NOTE: Should check that frame->magic == 0x53544448?
	 * Otherwise if we receive garbage at the beginning of the frame
	 * we may end up allocating a huge buffer and saving all the
	 * future incoming data into it.  */

	if (buf->len < sizeof(*frame) ||
			buf->len != le32_to_cpup(&frame->len)) {
		/* Save this fragment for later assembly */
		if (s->current_rx_buf)
			return 0;

		s->current_rx_buf = skb_copy_expand(skb, 0,
				le32_to_cpup(&frame->len), GFP_ATOMIC);
		if (!s->current_rx_buf) {
			netif_err(dev, ifup, dev->net, "Reserving %i bytes "
					"for packet assembly failed.\n",
					le32_to_cpup(&frame->len));
			dev->net->stats.rx_errors++;
		}

		return 0;
	}

	count = le32_to_cpup(&frame->pkt_cnt);

	skb_pull(buf, sizeof(*frame));

	while (count--) {
		if (buf->len < sizeof(*packet)) {
			netif_err(dev, ifup, dev->net, "Packet too short\n");
			goto error;
		}

		packet = (struct vl600_pkt_hdr *) buf->data;
		packet_len = sizeof(*packet) + le32_to_cpup(&packet->len);
		if (packet_len > buf->len) {
			netif_err(dev, ifup, dev->net,
					"Bad packet length stored in header\n");
			goto error;
		}

		/* Packet header is same size as the ethernet header
		 * (sizeof(*packet) == sizeof(*ethhdr)), additionally
		 * the h_proto field is in the same place so we just leave it
		 * alone and fill in the remaining fields.
		 */
		ethhdr = (struct ethhdr *) skb->data;
		if (be16_to_cpup(&ethhdr->h_proto) == ETH_P_ARP &&
				buf->len > 0x26) {
			/* Copy the addresses from packet contents */
			memcpy(ethhdr->h_source,
					&buf->data[sizeof(*ethhdr) + 0x8],
					ETH_ALEN);
			memcpy(ethhdr->h_dest,
					&buf->data[sizeof(*ethhdr) + 0x12],
					ETH_ALEN);
		} else {
			memset(ethhdr->h_source, 0, ETH_ALEN);
			memcpy(ethhdr->h_dest, dev->net->dev_addr, ETH_ALEN);
		}

		if (count) {
			/* Not the last packet in this batch */
			clone = skb_clone(buf, GFP_ATOMIC);
			if (!clone)
				goto error;

			skb_trim(clone, packet_len);
			usbnet_skb_return(dev, clone);

			skb_pull(buf, (packet_len + 3) & ~3);
		} else {
			skb_trim(buf, packet_len);

			if (s->current_rx_buf) {
				usbnet_skb_return(dev, buf);
				s->current_rx_buf = NULL;
				return 0;
			}

			return 1;
		}
	}

error:
	if (s->current_rx_buf) {
		dev_kfree_skb_any(s->current_rx_buf);
		s->current_rx_buf = NULL;
	}
	dev->net->stats.rx_errors++;
	return 0;
}

static struct sk_buff *vl600_tx_fixup(struct usbnet *dev,
		struct sk_buff *skb, gfp_t flags)
{
	struct sk_buff *ret;
	struct vl600_frame_hdr *frame;
	struct vl600_pkt_hdr *packet;
	static uint32_t serial = 1;
	int orig_len = skb->len - sizeof(struct ethhdr);
	int full_len = (skb->len + sizeof(struct vl600_frame_hdr) + 3) & ~3;

	frame = (struct vl600_frame_hdr *) skb->data;
	if (skb->len > sizeof(*frame) && skb->len == le32_to_cpup(&frame->len))
		return skb; /* Already encapsulated? */

	if (skb->len < sizeof(struct ethhdr))
		/* Drop, device can only deal with ethernet packets */
		return NULL;

	if (!skb_cloned(skb)) {
		int headroom = skb_headroom(skb);
		int tailroom = skb_tailroom(skb);

		if (tailroom >= full_len - skb->len - sizeof(*frame) &&
				headroom >= sizeof(*frame))
			/* There's enough head and tail room */
			goto encapsulate;

		if (headroom + tailroom + skb->len >= full_len) {
			/* There's enough total room, just readjust */
			skb->data = memmove(skb->head + sizeof(*frame),
					skb->data, skb->len);
			skb_set_tail_pointer(skb, skb->len);
			goto encapsulate;
		}
	}

	/* Alloc a new skb with the required size */
	ret = skb_copy_expand(skb, sizeof(struct vl600_frame_hdr), full_len -
			skb->len - sizeof(struct vl600_frame_hdr), flags);
	dev_kfree_skb_any(skb);
	if (!ret)
		return ret;
	skb = ret;

encapsulate:
	/* Packet header is same size as ethernet packet header
	 * (sizeof(*packet) == sizeof(struct ethhdr)), additionally the
	 * h_proto field is in the same place so we just leave it alone and
	 * overwrite the remaining fields.
	 */
	packet = (struct vl600_pkt_hdr *) skb->data;
	memset(&packet->dummy, 0, sizeof(packet->dummy));
	packet->len = cpu_to_le32(orig_len);

	frame = (struct vl600_frame_hdr *) skb_push(skb, sizeof(*frame));
	memset(frame, 0, sizeof(*frame));
	frame->len = cpu_to_le32(full_len);
	frame->serial = cpu_to_le32(serial++);
	frame->pkt_cnt = cpu_to_le32(1);

	if (skb->len < full_len) /* Pad */
		skb_put(skb, full_len - skb->len);

	return skb;
}

static const struct driver_info	vl600_info = {
	.description	= "LG VL600 modem",
	.flags		= FLAG_ETHER | FLAG_RX_ASSEMBLE,
	.bind		= vl600_bind,
	.unbind		= vl600_unbind,
	.status		= usbnet_cdc_status,
	.rx_fixup	= vl600_rx_fixup,
	.tx_fixup	= vl600_tx_fixup,
};

static const struct usb_device_id products[] = {
	{
		USB_DEVICE_AND_INTERFACE_INFO(0x1004, 0x61aa, USB_CLASS_COMM,
				USB_CDC_SUBCLASS_ETHERNET, USB_CDC_PROTO_NONE),
		.driver_info	= (unsigned long) &vl600_info,
	},
	{},	/* End */
};
MODULE_DEVICE_TABLE(usb, products);

static struct usb_driver lg_vl600_driver = {
	.name		= "lg-vl600",
	.id_table	= products,
	.probe		= usbnet_probe,
	.disconnect	= usbnet_disconnect,
	.suspend	= usbnet_suspend,
	.resume		= usbnet_resume,
};

static int __init vl600_init(void)
{
	return usb_register(&lg_vl600_driver);
}
module_init(vl600_init);

static void __exit vl600_exit(void)
{
	usb_deregister(&lg_vl600_driver);
}
module_exit(vl600_exit);

MODULE_AUTHOR("Anrzej Zaborowski");
MODULE_DESCRIPTION("LG-VL600 modem's ethernet link");
MODULE_LICENSE("GPL");