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, write to the Free Software 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 */ 21 #include <linux/etherdevice.h> 22 #include <linux/ethtool.h> 23 #include <linux/mii.h> 24 #include <linux/usb.h> 25 #include <linux/usb/cdc.h> 26 #include <linux/usb/usbnet.h> 27 #include <linux/if_ether.h> 28 #include <linux/if_arp.h> 29 #include <linux/inetdevice.h> 30 #include <linux/module.h> 31 32 /* 33 * The device has a CDC ACM port for modem control (it claims to be 34 * CDC ACM anyway) and a CDC Ethernet port for actual network data. 35 * It will however ignore data on both ports that is not encapsulated 36 * in a specific way, any data returned is also encapsulated the same 37 * way. The headers don't seem to follow any popular standard. 38 * 39 * This driver adds and strips these headers from the ethernet frames 40 * sent/received from the CDC Ethernet port. The proprietary header 41 * replaces the standard ethernet header in a packet so only actual 42 * ethernet frames are allowed. The headers allow some form of 43 * multiplexing by using non standard values of the .h_proto field. 44 * Windows/Mac drivers do send a couple of such frames to the device 45 * during initialisation, with protocol set to 0x0906 or 0x0b06 and (what 46 * seems to be) a flag in the .dummy_flags. This doesn't seem necessary 47 * for modem operation but can possibly be used for GPS or other funcitons. 48 */ 49 50 struct vl600_frame_hdr { 51 __le32 len; 52 __le32 serial; 53 __le32 pkt_cnt; 54 __le32 dummy_flags; 55 __le32 dummy; 56 __le32 magic; 57 } __attribute__((packed)); 58 59 struct vl600_pkt_hdr { 60 __le32 dummy[2]; 61 __le32 len; 62 __be16 h_proto; 63 } __attribute__((packed)); 64 65 struct vl600_state { 66 struct sk_buff *current_rx_buf; 67 }; 68 69 static int vl600_bind(struct usbnet *dev, struct usb_interface *intf) 70 { 71 int ret; 72 struct vl600_state *s = kzalloc(sizeof(struct vl600_state), GFP_KERNEL); 73 74 if (!s) 75 return -ENOMEM; 76 77 ret = usbnet_cdc_bind(dev, intf); 78 if (ret) { 79 kfree(s); 80 return ret; 81 } 82 83 dev->driver_priv = s; 84 85 /* ARP packets don't go through, but they're also of no use. The 86 * subnet has only two hosts anyway: us and the gateway / DHCP 87 * server (probably simulated by modem firmware or network operator) 88 * whose address changes everytime we connect to the intarwebz and 89 * who doesn't bother answering ARP requests either. So hardware 90 * addresses have no meaning, the destination and the source of every 91 * packet depend only on whether it is on the IN or OUT endpoint. */ 92 dev->net->flags |= IFF_NOARP; 93 /* IPv6 NDP relies on multicast. Enable it by default. */ 94 dev->net->flags |= IFF_MULTICAST; 95 96 return ret; 97 } 98 99 static void vl600_unbind(struct usbnet *dev, struct usb_interface *intf) 100 { 101 struct vl600_state *s = dev->driver_priv; 102 103 if (s->current_rx_buf) 104 dev_kfree_skb(s->current_rx_buf); 105 106 kfree(s); 107 108 return usbnet_cdc_unbind(dev, intf); 109 } 110 111 static int vl600_rx_fixup(struct usbnet *dev, struct sk_buff *skb) 112 { 113 struct vl600_frame_hdr *frame; 114 struct vl600_pkt_hdr *packet; 115 struct ethhdr *ethhdr; 116 int packet_len, count; 117 struct sk_buff *buf = skb; 118 struct sk_buff *clone; 119 struct vl600_state *s = dev->driver_priv; 120 121 /* Frame lengths are generally 4B multiplies but every couple of 122 * hours there's an odd number of bytes sized yet correct frame, 123 * so don't require this. */ 124 125 /* Allow a packet (or multiple packets batched together) to be 126 * split across many frames. We don't allow a new batch to 127 * begin in the same frame another one is ending however, and no 128 * leading or trailing pad bytes. */ 129 if (s->current_rx_buf) { 130 frame = (struct vl600_frame_hdr *) s->current_rx_buf->data; 131 if (skb->len + s->current_rx_buf->len > 132 le32_to_cpup(&frame->len)) { 133 netif_err(dev, ifup, dev->net, "Fragment too long\n"); 134 dev->net->stats.rx_length_errors++; 135 goto error; 136 } 137 138 buf = s->current_rx_buf; 139 memcpy(skb_put(buf, skb->len), skb->data, skb->len); 140 } else if (skb->len < 4) { 141 netif_err(dev, ifup, dev->net, "Frame too short\n"); 142 dev->net->stats.rx_length_errors++; 143 goto error; 144 } 145 146 frame = (struct vl600_frame_hdr *) buf->data; 147 /* Yes, check that frame->magic == 0x53544448 (or 0x44544d48), 148 * otherwise we may run out of memory w/a bad packet */ 149 if (ntohl(frame->magic) != 0x53544448 && 150 ntohl(frame->magic) != 0x44544d48) 151 goto error; 152 153 if (buf->len < sizeof(*frame) || 154 buf->len != le32_to_cpup(&frame->len)) { 155 /* Save this fragment for later assembly */ 156 if (s->current_rx_buf) 157 return 0; 158 159 s->current_rx_buf = skb_copy_expand(skb, 0, 160 le32_to_cpup(&frame->len), GFP_ATOMIC); 161 if (!s->current_rx_buf) { 162 netif_err(dev, ifup, dev->net, "Reserving %i bytes " 163 "for packet assembly failed.\n", 164 le32_to_cpup(&frame->len)); 165 dev->net->stats.rx_errors++; 166 } 167 168 return 0; 169 } 170 171 count = le32_to_cpup(&frame->pkt_cnt); 172 173 skb_pull(buf, sizeof(*frame)); 174 175 while (count--) { 176 if (buf->len < sizeof(*packet)) { 177 netif_err(dev, ifup, dev->net, "Packet too short\n"); 178 goto error; 179 } 180 181 packet = (struct vl600_pkt_hdr *) buf->data; 182 packet_len = sizeof(*packet) + le32_to_cpup(&packet->len); 183 if (packet_len > buf->len) { 184 netif_err(dev, ifup, dev->net, 185 "Bad packet length stored in header\n"); 186 goto error; 187 } 188 189 /* Packet header is same size as the ethernet header 190 * (sizeof(*packet) == sizeof(*ethhdr)), additionally 191 * the h_proto field is in the same place so we just leave it 192 * alone and fill in the remaining fields. 193 */ 194 ethhdr = (struct ethhdr *) skb->data; 195 if (be16_to_cpup(ðhdr->h_proto) == ETH_P_ARP && 196 buf->len > 0x26) { 197 /* Copy the addresses from packet contents */ 198 memcpy(ethhdr->h_source, 199 &buf->data[sizeof(*ethhdr) + 0x8], 200 ETH_ALEN); 201 memcpy(ethhdr->h_dest, 202 &buf->data[sizeof(*ethhdr) + 0x12], 203 ETH_ALEN); 204 } else { 205 memset(ethhdr->h_source, 0, ETH_ALEN); 206 memcpy(ethhdr->h_dest, dev->net->dev_addr, ETH_ALEN); 207 208 /* Inbound IPv6 packets have an IPv4 ethertype (0x800) 209 * for some reason. Peek at the L3 header to check 210 * for IPv6 packets, and set the ethertype to IPv6 211 * (0x86dd) so Linux can understand it. 212 */ 213 if ((buf->data[sizeof(*ethhdr)] & 0xf0) == 0x60) 214 ethhdr->h_proto = __constant_htons(ETH_P_IPV6); 215 } 216 217 if (count) { 218 /* Not the last packet in this batch */ 219 clone = skb_clone(buf, GFP_ATOMIC); 220 if (!clone) 221 goto error; 222 223 skb_trim(clone, packet_len); 224 usbnet_skb_return(dev, clone); 225 226 skb_pull(buf, (packet_len + 3) & ~3); 227 } else { 228 skb_trim(buf, packet_len); 229 230 if (s->current_rx_buf) { 231 usbnet_skb_return(dev, buf); 232 s->current_rx_buf = NULL; 233 return 0; 234 } 235 236 return 1; 237 } 238 } 239 240 error: 241 if (s->current_rx_buf) { 242 dev_kfree_skb_any(s->current_rx_buf); 243 s->current_rx_buf = NULL; 244 } 245 dev->net->stats.rx_errors++; 246 return 0; 247 } 248 249 static struct sk_buff *vl600_tx_fixup(struct usbnet *dev, 250 struct sk_buff *skb, gfp_t flags) 251 { 252 struct sk_buff *ret; 253 struct vl600_frame_hdr *frame; 254 struct vl600_pkt_hdr *packet; 255 static uint32_t serial = 1; 256 int orig_len = skb->len - sizeof(struct ethhdr); 257 int full_len = (skb->len + sizeof(struct vl600_frame_hdr) + 3) & ~3; 258 259 frame = (struct vl600_frame_hdr *) skb->data; 260 if (skb->len > sizeof(*frame) && skb->len == le32_to_cpup(&frame->len)) 261 return skb; /* Already encapsulated? */ 262 263 if (skb->len < sizeof(struct ethhdr)) 264 /* Drop, device can only deal with ethernet packets */ 265 return NULL; 266 267 if (!skb_cloned(skb)) { 268 int headroom = skb_headroom(skb); 269 int tailroom = skb_tailroom(skb); 270 271 if (tailroom >= full_len - skb->len - sizeof(*frame) && 272 headroom >= sizeof(*frame)) 273 /* There's enough head and tail room */ 274 goto encapsulate; 275 276 if (headroom + tailroom + skb->len >= full_len) { 277 /* There's enough total room, just readjust */ 278 skb->data = memmove(skb->head + sizeof(*frame), 279 skb->data, skb->len); 280 skb_set_tail_pointer(skb, skb->len); 281 goto encapsulate; 282 } 283 } 284 285 /* Alloc a new skb with the required size */ 286 ret = skb_copy_expand(skb, sizeof(struct vl600_frame_hdr), full_len - 287 skb->len - sizeof(struct vl600_frame_hdr), flags); 288 dev_kfree_skb_any(skb); 289 if (!ret) 290 return ret; 291 skb = ret; 292 293 encapsulate: 294 /* Packet header is same size as ethernet packet header 295 * (sizeof(*packet) == sizeof(struct ethhdr)), additionally the 296 * h_proto field is in the same place so we just leave it alone and 297 * overwrite the remaining fields. 298 */ 299 packet = (struct vl600_pkt_hdr *) skb->data; 300 /* The VL600 wants IPv6 packets to have an IPv4 ethertype 301 * Since this modem only supports IPv4 and IPv6, just set all 302 * frames to 0x0800 (ETH_P_IP) 303 */ 304 packet->h_proto = htons(ETH_P_IP); 305 memset(&packet->dummy, 0, sizeof(packet->dummy)); 306 packet->len = cpu_to_le32(orig_len); 307 308 frame = (struct vl600_frame_hdr *) skb_push(skb, sizeof(*frame)); 309 memset(frame, 0, sizeof(*frame)); 310 frame->len = cpu_to_le32(full_len); 311 frame->serial = cpu_to_le32(serial++); 312 frame->pkt_cnt = cpu_to_le32(1); 313 314 if (skb->len < full_len) /* Pad */ 315 skb_put(skb, full_len - skb->len); 316 317 return skb; 318 } 319 320 static const struct driver_info vl600_info = { 321 .description = "LG VL600 modem", 322 .flags = FLAG_RX_ASSEMBLE | FLAG_WWAN, 323 .bind = vl600_bind, 324 .unbind = vl600_unbind, 325 .status = usbnet_cdc_status, 326 .rx_fixup = vl600_rx_fixup, 327 .tx_fixup = vl600_tx_fixup, 328 }; 329 330 static const struct usb_device_id products[] = { 331 { 332 USB_DEVICE_AND_INTERFACE_INFO(0x1004, 0x61aa, USB_CLASS_COMM, 333 USB_CDC_SUBCLASS_ETHERNET, USB_CDC_PROTO_NONE), 334 .driver_info = (unsigned long) &vl600_info, 335 }, 336 {}, /* End */ 337 }; 338 MODULE_DEVICE_TABLE(usb, products); 339 340 static struct usb_driver lg_vl600_driver = { 341 .name = "lg-vl600", 342 .id_table = products, 343 .probe = usbnet_probe, 344 .disconnect = usbnet_disconnect, 345 .suspend = usbnet_suspend, 346 .resume = usbnet_resume, 347 .disable_hub_initiated_lpm = 1, 348 }; 349 350 module_usb_driver(lg_vl600_driver); 351 352 MODULE_AUTHOR("Anrzej Zaborowski"); 353 MODULE_DESCRIPTION("LG-VL600 modem's ethernet link"); 354 MODULE_LICENSE("GPL"); 355