1 /*
2 * Ethernet interface part of the LG VL600 LTE modem (4G dongle)
3 *
4 * Copyright (C) 2011 Intel Corporation
5 * Author: Andrzej Zaborowski <balrogg@gmail.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, see <http://www.gnu.org/licenses/>.
19 */
20 #include <linux/etherdevice.h>
21 #include <linux/ethtool.h>
22 #include <linux/mii.h>
23 #include <linux/usb.h>
24 #include <linux/usb/cdc.h>
25 #include <linux/usb/usbnet.h>
26 #include <linux/if_ether.h>
27 #include <linux/if_arp.h>
28 #include <linux/inetdevice.h>
29 #include <linux/module.h>
30
31 /*
32 * The device has a CDC ACM port for modem control (it claims to be
33 * CDC ACM anyway) and a CDC Ethernet port for actual network data.
34 * It will however ignore data on both ports that is not encapsulated
35 * in a specific way, any data returned is also encapsulated the same
36 * way. The headers don't seem to follow any popular standard.
37 *
38 * This driver adds and strips these headers from the ethernet frames
39 * sent/received from the CDC Ethernet port. The proprietary header
40 * replaces the standard ethernet header in a packet so only actual
41 * ethernet frames are allowed. The headers allow some form of
42 * multiplexing by using non standard values of the .h_proto field.
43 * Windows/Mac drivers do send a couple of such frames to the device
44 * during initialisation, with protocol set to 0x0906 or 0x0b06 and (what
45 * seems to be) a flag in the .dummy_flags. This doesn't seem necessary
46 * for modem operation but can possibly be used for GPS or other funcitons.
47 */
48
49 struct vl600_frame_hdr {
50 __le32 len;
51 __le32 serial;
52 __le32 pkt_cnt;
53 __le32 dummy_flags;
54 __le32 dummy;
55 __le32 magic;
56 } __attribute__((packed));
57
58 struct vl600_pkt_hdr {
59 __le32 dummy[2];
60 __le32 len;
61 __be16 h_proto;
62 } __attribute__((packed));
63
64 struct vl600_state {
65 struct sk_buff *current_rx_buf;
66 };
67
vl600_bind(struct usbnet * dev,struct usb_interface * intf)68 static int vl600_bind(struct usbnet *dev, struct usb_interface *intf)
69 {
70 int ret;
71 struct vl600_state *s = kzalloc(sizeof(struct vl600_state), GFP_KERNEL);
72
73 if (!s)
74 return -ENOMEM;
75
76 ret = usbnet_cdc_bind(dev, intf);
77 if (ret) {
78 kfree(s);
79 return ret;
80 }
81
82 dev->driver_priv = s;
83
84 /* ARP packets don't go through, but they're also of no use. The
85 * subnet has only two hosts anyway: us and the gateway / DHCP
86 * server (probably simulated by modem firmware or network operator)
87 * whose address changes everytime we connect to the intarwebz and
88 * who doesn't bother answering ARP requests either. So hardware
89 * addresses have no meaning, the destination and the source of every
90 * packet depend only on whether it is on the IN or OUT endpoint. */
91 dev->net->flags |= IFF_NOARP;
92 /* IPv6 NDP relies on multicast. Enable it by default. */
93 dev->net->flags |= IFF_MULTICAST;
94
95 return ret;
96 }
97
vl600_unbind(struct usbnet * dev,struct usb_interface * intf)98 static void vl600_unbind(struct usbnet *dev, struct usb_interface *intf)
99 {
100 struct vl600_state *s = dev->driver_priv;
101
102 if (s->current_rx_buf)
103 dev_kfree_skb(s->current_rx_buf);
104
105 kfree(s);
106
107 return usbnet_cdc_unbind(dev, intf);
108 }
109
vl600_rx_fixup(struct usbnet * dev,struct sk_buff * skb)110 static int vl600_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
111 {
112 struct vl600_frame_hdr *frame;
113 struct vl600_pkt_hdr *packet;
114 struct ethhdr *ethhdr;
115 int packet_len, count;
116 struct sk_buff *buf = skb;
117 struct sk_buff *clone;
118 struct vl600_state *s = dev->driver_priv;
119
120 /* Frame lengths are generally 4B multiplies but every couple of
121 * hours there's an odd number of bytes sized yet correct frame,
122 * so don't require this. */
123
124 /* Allow a packet (or multiple packets batched together) to be
125 * split across many frames. We don't allow a new batch to
126 * begin in the same frame another one is ending however, and no
127 * leading or trailing pad bytes. */
128 if (s->current_rx_buf) {
129 frame = (struct vl600_frame_hdr *) s->current_rx_buf->data;
130 if (skb->len + s->current_rx_buf->len >
131 le32_to_cpup(&frame->len)) {
132 netif_err(dev, ifup, dev->net, "Fragment too long\n");
133 dev->net->stats.rx_length_errors++;
134 goto error;
135 }
136
137 buf = s->current_rx_buf;
138 memcpy(skb_put(buf, skb->len), skb->data, skb->len);
139 } else if (skb->len < 4) {
140 netif_err(dev, ifup, dev->net, "Frame too short\n");
141 dev->net->stats.rx_length_errors++;
142 goto error;
143 }
144
145 frame = (struct vl600_frame_hdr *) buf->data;
146 /* Yes, check that frame->magic == 0x53544448 (or 0x44544d48),
147 * otherwise we may run out of memory w/a bad packet */
148 if (ntohl(frame->magic) != 0x53544448 &&
149 ntohl(frame->magic) != 0x44544d48)
150 goto error;
151
152 if (buf->len < sizeof(*frame) ||
153 buf->len != le32_to_cpup(&frame->len)) {
154 /* Save this fragment for later assembly */
155 if (s->current_rx_buf)
156 return 0;
157
158 s->current_rx_buf = skb_copy_expand(skb, 0,
159 le32_to_cpup(&frame->len), GFP_ATOMIC);
160 if (!s->current_rx_buf) {
161 netif_err(dev, ifup, dev->net, "Reserving %i bytes "
162 "for packet assembly failed.\n",
163 le32_to_cpup(&frame->len));
164 dev->net->stats.rx_errors++;
165 }
166
167 return 0;
168 }
169
170 count = le32_to_cpup(&frame->pkt_cnt);
171
172 skb_pull(buf, sizeof(*frame));
173
174 while (count--) {
175 if (buf->len < sizeof(*packet)) {
176 netif_err(dev, ifup, dev->net, "Packet too short\n");
177 goto error;
178 }
179
180 packet = (struct vl600_pkt_hdr *) buf->data;
181 packet_len = sizeof(*packet) + le32_to_cpup(&packet->len);
182 if (packet_len > buf->len) {
183 netif_err(dev, ifup, dev->net,
184 "Bad packet length stored in header\n");
185 goto error;
186 }
187
188 /* Packet header is same size as the ethernet header
189 * (sizeof(*packet) == sizeof(*ethhdr)), additionally
190 * the h_proto field is in the same place so we just leave it
191 * alone and fill in the remaining fields.
192 */
193 ethhdr = (struct ethhdr *) skb->data;
194 if (be16_to_cpup(ðhdr->h_proto) == ETH_P_ARP &&
195 buf->len > 0x26) {
196 /* Copy the addresses from packet contents */
197 memcpy(ethhdr->h_source,
198 &buf->data[sizeof(*ethhdr) + 0x8],
199 ETH_ALEN);
200 memcpy(ethhdr->h_dest,
201 &buf->data[sizeof(*ethhdr) + 0x12],
202 ETH_ALEN);
203 } else {
204 memset(ethhdr->h_source, 0, ETH_ALEN);
205 memcpy(ethhdr->h_dest, dev->net->dev_addr, ETH_ALEN);
206
207 /* Inbound IPv6 packets have an IPv4 ethertype (0x800)
208 * for some reason. Peek at the L3 header to check
209 * for IPv6 packets, and set the ethertype to IPv6
210 * (0x86dd) so Linux can understand it.
211 */
212 if ((buf->data[sizeof(*ethhdr)] & 0xf0) == 0x60)
213 ethhdr->h_proto = htons(ETH_P_IPV6);
214 }
215
216 if (count) {
217 /* Not the last packet in this batch */
218 clone = skb_clone(buf, GFP_ATOMIC);
219 if (!clone)
220 goto error;
221
222 skb_trim(clone, packet_len);
223 usbnet_skb_return(dev, clone);
224
225 skb_pull(buf, (packet_len + 3) & ~3);
226 } else {
227 skb_trim(buf, packet_len);
228
229 if (s->current_rx_buf) {
230 usbnet_skb_return(dev, buf);
231 s->current_rx_buf = NULL;
232 return 0;
233 }
234
235 return 1;
236 }
237 }
238
239 error:
240 if (s->current_rx_buf) {
241 dev_kfree_skb_any(s->current_rx_buf);
242 s->current_rx_buf = NULL;
243 }
244 dev->net->stats.rx_errors++;
245 return 0;
246 }
247
vl600_tx_fixup(struct usbnet * dev,struct sk_buff * skb,gfp_t flags)248 static struct sk_buff *vl600_tx_fixup(struct usbnet *dev,
249 struct sk_buff *skb, gfp_t flags)
250 {
251 struct sk_buff *ret;
252 struct vl600_frame_hdr *frame;
253 struct vl600_pkt_hdr *packet;
254 static uint32_t serial = 1;
255 int orig_len = skb->len - sizeof(struct ethhdr);
256 int full_len = (skb->len + sizeof(struct vl600_frame_hdr) + 3) & ~3;
257
258 frame = (struct vl600_frame_hdr *) skb->data;
259 if (skb->len > sizeof(*frame) && skb->len == le32_to_cpup(&frame->len))
260 return skb; /* Already encapsulated? */
261
262 if (skb->len < sizeof(struct ethhdr))
263 /* Drop, device can only deal with ethernet packets */
264 return NULL;
265
266 if (!skb_cloned(skb)) {
267 int headroom = skb_headroom(skb);
268 int tailroom = skb_tailroom(skb);
269
270 if (tailroom >= full_len - skb->len - sizeof(*frame) &&
271 headroom >= sizeof(*frame))
272 /* There's enough head and tail room */
273 goto encapsulate;
274
275 if (headroom + tailroom + skb->len >= full_len) {
276 /* There's enough total room, just readjust */
277 skb->data = memmove(skb->head + sizeof(*frame),
278 skb->data, skb->len);
279 skb_set_tail_pointer(skb, skb->len);
280 goto encapsulate;
281 }
282 }
283
284 /* Alloc a new skb with the required size */
285 ret = skb_copy_expand(skb, sizeof(struct vl600_frame_hdr), full_len -
286 skb->len - sizeof(struct vl600_frame_hdr), flags);
287 dev_kfree_skb_any(skb);
288 if (!ret)
289 return ret;
290 skb = ret;
291
292 encapsulate:
293 /* Packet header is same size as ethernet packet header
294 * (sizeof(*packet) == sizeof(struct ethhdr)), additionally the
295 * h_proto field is in the same place so we just leave it alone and
296 * overwrite the remaining fields.
297 */
298 packet = (struct vl600_pkt_hdr *) skb->data;
299 /* The VL600 wants IPv6 packets to have an IPv4 ethertype
300 * Since this modem only supports IPv4 and IPv6, just set all
301 * frames to 0x0800 (ETH_P_IP)
302 */
303 packet->h_proto = htons(ETH_P_IP);
304 memset(&packet->dummy, 0, sizeof(packet->dummy));
305 packet->len = cpu_to_le32(orig_len);
306
307 frame = (struct vl600_frame_hdr *) skb_push(skb, sizeof(*frame));
308 memset(frame, 0, sizeof(*frame));
309 frame->len = cpu_to_le32(full_len);
310 frame->serial = cpu_to_le32(serial++);
311 frame->pkt_cnt = cpu_to_le32(1);
312
313 if (skb->len < full_len) /* Pad */
314 skb_put(skb, full_len - skb->len);
315
316 return skb;
317 }
318
319 static const struct driver_info vl600_info = {
320 .description = "LG VL600 modem",
321 .flags = FLAG_RX_ASSEMBLE | FLAG_WWAN,
322 .bind = vl600_bind,
323 .unbind = vl600_unbind,
324 .status = usbnet_cdc_status,
325 .rx_fixup = vl600_rx_fixup,
326 .tx_fixup = vl600_tx_fixup,
327 };
328
329 static const struct usb_device_id products[] = {
330 {
331 USB_DEVICE_AND_INTERFACE_INFO(0x1004, 0x61aa, USB_CLASS_COMM,
332 USB_CDC_SUBCLASS_ETHERNET, USB_CDC_PROTO_NONE),
333 .driver_info = (unsigned long) &vl600_info,
334 },
335 {}, /* End */
336 };
337 MODULE_DEVICE_TABLE(usb, products);
338
339 static struct usb_driver lg_vl600_driver = {
340 .name = "lg-vl600",
341 .id_table = products,
342 .probe = usbnet_probe,
343 .disconnect = usbnet_disconnect,
344 .suspend = usbnet_suspend,
345 .resume = usbnet_resume,
346 .disable_hub_initiated_lpm = 1,
347 };
348
349 module_usb_driver(lg_vl600_driver);
350
351 MODULE_AUTHOR("Anrzej Zaborowski");
352 MODULE_DESCRIPTION("LG-VL600 modem's ethernet link");
353 MODULE_LICENSE("GPL");
354