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, 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(&ethhdr->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 };
 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");