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 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 93 return ret; 94 } 95 96 static void vl600_unbind(struct usbnet *dev, struct usb_interface *intf) 97 { 98 struct vl600_state *s = dev->driver_priv; 99 100 if (s->current_rx_buf) 101 dev_kfree_skb(s->current_rx_buf); 102 103 kfree(s); 104 105 return usbnet_cdc_unbind(dev, intf); 106 } 107 108 static int vl600_rx_fixup(struct usbnet *dev, struct sk_buff *skb) 109 { 110 struct vl600_frame_hdr *frame; 111 struct vl600_pkt_hdr *packet; 112 struct ethhdr *ethhdr; 113 int packet_len, count; 114 struct sk_buff *buf = skb; 115 struct sk_buff *clone; 116 struct vl600_state *s = dev->driver_priv; 117 118 /* Frame lengths are generally 4B multiplies but every couple of 119 * hours there's an odd number of bytes sized yet correct frame, 120 * so don't require this. */ 121 122 /* Allow a packet (or multiple packets batched together) to be 123 * split across many frames. We don't allow a new batch to 124 * begin in the same frame another one is ending however, and no 125 * leading or trailing pad bytes. */ 126 if (s->current_rx_buf) { 127 frame = (struct vl600_frame_hdr *) s->current_rx_buf->data; 128 if (skb->len + s->current_rx_buf->len > 129 le32_to_cpup(&frame->len)) { 130 netif_err(dev, ifup, dev->net, "Fragment too long\n"); 131 dev->net->stats.rx_length_errors++; 132 goto error; 133 } 134 135 buf = s->current_rx_buf; 136 memcpy(skb_put(buf, skb->len), skb->data, skb->len); 137 } else if (skb->len < 4) { 138 netif_err(dev, ifup, dev->net, "Frame too short\n"); 139 dev->net->stats.rx_length_errors++; 140 goto error; 141 } 142 143 frame = (struct vl600_frame_hdr *) buf->data; 144 /* NOTE: Should check that frame->magic == 0x53544448? 145 * Otherwise if we receive garbage at the beginning of the frame 146 * we may end up allocating a huge buffer and saving all the 147 * future incoming data into it. */ 148 149 if (buf->len < sizeof(*frame) || 150 buf->len != le32_to_cpup(&frame->len)) { 151 /* Save this fragment for later assembly */ 152 if (s->current_rx_buf) 153 return 0; 154 155 s->current_rx_buf = skb_copy_expand(skb, 0, 156 le32_to_cpup(&frame->len), GFP_ATOMIC); 157 if (!s->current_rx_buf) { 158 netif_err(dev, ifup, dev->net, "Reserving %i bytes " 159 "for packet assembly failed.\n", 160 le32_to_cpup(&frame->len)); 161 dev->net->stats.rx_errors++; 162 } 163 164 return 0; 165 } 166 167 count = le32_to_cpup(&frame->pkt_cnt); 168 169 skb_pull(buf, sizeof(*frame)); 170 171 while (count--) { 172 if (buf->len < sizeof(*packet)) { 173 netif_err(dev, ifup, dev->net, "Packet too short\n"); 174 goto error; 175 } 176 177 packet = (struct vl600_pkt_hdr *) buf->data; 178 packet_len = sizeof(*packet) + le32_to_cpup(&packet->len); 179 if (packet_len > buf->len) { 180 netif_err(dev, ifup, dev->net, 181 "Bad packet length stored in header\n"); 182 goto error; 183 } 184 185 /* Packet header is same size as the ethernet header 186 * (sizeof(*packet) == sizeof(*ethhdr)), additionally 187 * the h_proto field is in the same place so we just leave it 188 * alone and fill in the remaining fields. 189 */ 190 ethhdr = (struct ethhdr *) skb->data; 191 if (be16_to_cpup(ðhdr->h_proto) == ETH_P_ARP && 192 buf->len > 0x26) { 193 /* Copy the addresses from packet contents */ 194 memcpy(ethhdr->h_source, 195 &buf->data[sizeof(*ethhdr) + 0x8], 196 ETH_ALEN); 197 memcpy(ethhdr->h_dest, 198 &buf->data[sizeof(*ethhdr) + 0x12], 199 ETH_ALEN); 200 } else { 201 memset(ethhdr->h_source, 0, ETH_ALEN); 202 memcpy(ethhdr->h_dest, dev->net->dev_addr, ETH_ALEN); 203 } 204 205 if (count) { 206 /* Not the last packet in this batch */ 207 clone = skb_clone(buf, GFP_ATOMIC); 208 if (!clone) 209 goto error; 210 211 skb_trim(clone, packet_len); 212 usbnet_skb_return(dev, clone); 213 214 skb_pull(buf, (packet_len + 3) & ~3); 215 } else { 216 skb_trim(buf, packet_len); 217 218 if (s->current_rx_buf) { 219 usbnet_skb_return(dev, buf); 220 s->current_rx_buf = NULL; 221 return 0; 222 } 223 224 return 1; 225 } 226 } 227 228 error: 229 if (s->current_rx_buf) { 230 dev_kfree_skb_any(s->current_rx_buf); 231 s->current_rx_buf = NULL; 232 } 233 dev->net->stats.rx_errors++; 234 return 0; 235 } 236 237 static struct sk_buff *vl600_tx_fixup(struct usbnet *dev, 238 struct sk_buff *skb, gfp_t flags) 239 { 240 struct sk_buff *ret; 241 struct vl600_frame_hdr *frame; 242 struct vl600_pkt_hdr *packet; 243 static uint32_t serial = 1; 244 int orig_len = skb->len - sizeof(struct ethhdr); 245 int full_len = (skb->len + sizeof(struct vl600_frame_hdr) + 3) & ~3; 246 247 frame = (struct vl600_frame_hdr *) skb->data; 248 if (skb->len > sizeof(*frame) && skb->len == le32_to_cpup(&frame->len)) 249 return skb; /* Already encapsulated? */ 250 251 if (skb->len < sizeof(struct ethhdr)) 252 /* Drop, device can only deal with ethernet packets */ 253 return NULL; 254 255 if (!skb_cloned(skb)) { 256 int headroom = skb_headroom(skb); 257 int tailroom = skb_tailroom(skb); 258 259 if (tailroom >= full_len - skb->len - sizeof(*frame) && 260 headroom >= sizeof(*frame)) 261 /* There's enough head and tail room */ 262 goto encapsulate; 263 264 if (headroom + tailroom + skb->len >= full_len) { 265 /* There's enough total room, just readjust */ 266 skb->data = memmove(skb->head + sizeof(*frame), 267 skb->data, skb->len); 268 skb_set_tail_pointer(skb, skb->len); 269 goto encapsulate; 270 } 271 } 272 273 /* Alloc a new skb with the required size */ 274 ret = skb_copy_expand(skb, sizeof(struct vl600_frame_hdr), full_len - 275 skb->len - sizeof(struct vl600_frame_hdr), flags); 276 dev_kfree_skb_any(skb); 277 if (!ret) 278 return ret; 279 skb = ret; 280 281 encapsulate: 282 /* Packet header is same size as ethernet packet header 283 * (sizeof(*packet) == sizeof(struct ethhdr)), additionally the 284 * h_proto field is in the same place so we just leave it alone and 285 * overwrite the remaining fields. 286 */ 287 packet = (struct vl600_pkt_hdr *) skb->data; 288 memset(&packet->dummy, 0, sizeof(packet->dummy)); 289 packet->len = cpu_to_le32(orig_len); 290 291 frame = (struct vl600_frame_hdr *) skb_push(skb, sizeof(*frame)); 292 memset(frame, 0, sizeof(*frame)); 293 frame->len = cpu_to_le32(full_len); 294 frame->serial = cpu_to_le32(serial++); 295 frame->pkt_cnt = cpu_to_le32(1); 296 297 if (skb->len < full_len) /* Pad */ 298 skb_put(skb, full_len - skb->len); 299 300 return skb; 301 } 302 303 static const struct driver_info vl600_info = { 304 .description = "LG VL600 modem", 305 .flags = FLAG_ETHER | FLAG_RX_ASSEMBLE, 306 .bind = vl600_bind, 307 .unbind = vl600_unbind, 308 .status = usbnet_cdc_status, 309 .rx_fixup = vl600_rx_fixup, 310 .tx_fixup = vl600_tx_fixup, 311 }; 312 313 static const struct usb_device_id products[] = { 314 { 315 USB_DEVICE_AND_INTERFACE_INFO(0x1004, 0x61aa, USB_CLASS_COMM, 316 USB_CDC_SUBCLASS_ETHERNET, USB_CDC_PROTO_NONE), 317 .driver_info = (unsigned long) &vl600_info, 318 }, 319 {}, /* End */ 320 }; 321 MODULE_DEVICE_TABLE(usb, products); 322 323 static struct usb_driver lg_vl600_driver = { 324 .name = "lg-vl600", 325 .id_table = products, 326 .probe = usbnet_probe, 327 .disconnect = usbnet_disconnect, 328 .suspend = usbnet_suspend, 329 .resume = usbnet_resume, 330 }; 331 332 static int __init vl600_init(void) 333 { 334 return usb_register(&lg_vl600_driver); 335 } 336 module_init(vl600_init); 337 338 static void __exit vl600_exit(void) 339 { 340 usb_deregister(&lg_vl600_driver); 341 } 342 module_exit(vl600_exit); 343 344 MODULE_AUTHOR("Anrzej Zaborowski"); 345 MODULE_DESCRIPTION("LG-VL600 modem's ethernet link"); 346 MODULE_LICENSE("GPL"); 347