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Linux/drivers/net/usb/lg-vl600.c

  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 
 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 
 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 
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(&ethhdr->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 = __constant_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 
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 

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