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 skb_put_data(buf, 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 eth_zero_addr(ethhdr->h_source); 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 } 247 248 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 = 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