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                 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                         dev->net->stats.rx_errors++;
 162
 163                 return 0;
 164         }
 165
 166         count = le32_to_cpup(&frame->pkt_cnt);
 167
 168         skb_pull(buf, sizeof(*frame));
 169
 170         while (count--) {
 171                 if (buf->len < sizeof(*packet)) {
 172                         netif_err(dev, ifup, dev->net, "Packet too short\n");
 173                         goto error;
 174                 }
 175
 176                 packet = (struct vl600_pkt_hdr *) buf->data;
 177                 packet_len = sizeof(*packet) + le32_to_cpup(&packet->len);
 178                 if (packet_len > buf->len) {
 179                         netif_err(dev, ifup, dev->net,
 180                                         "Bad packet length stored in header\n");
 181                         goto error;
 182                 }
 183
 184                 /* Packet header is same size as the ethernet header
 185                  * (sizeof(*packet) == sizeof(*ethhdr)), additionally
 186                  * the h_proto field is in the same place so we just leave it
 187                  * alone and fill in the remaining fields.
 188                  */
 189                 ethhdr = (struct ethhdr *) skb->data;
 190                 if (be16_to_cpup(&ethhdr->h_proto) == ETH_P_ARP &&
 191                                 buf->len > 0x26) {
 192                         /* Copy the addresses from packet contents */
 193                         memcpy(ethhdr->h_source,
 194                                         &buf->data[sizeof(*ethhdr) + 0x8],
 195                                         ETH_ALEN);
 196                         memcpy(ethhdr->h_dest,
 197                                         &buf->data[sizeof(*ethhdr) + 0x12],
 198                                         ETH_ALEN);
 199                 } else {
 200                         eth_zero_addr(ethhdr->h_source);
 201                         memcpy(ethhdr->h_dest, dev->net->dev_addr, ETH_ALEN);
 202
 203                         /* Inbound IPv6 packets have an IPv4 ethertype (0x800)
 204                          * for some reason.  Peek at the L3 header to check
 205                          * for IPv6 packets, and set the ethertype to IPv6
 206                          * (0x86dd) so Linux can understand it.
 207                          */
 208                         if ((buf->data[sizeof(*ethhdr)] & 0xf0) == 0x60)
 209                                 ethhdr->h_proto = htons(ETH_P_IPV6);
 210                 }
 211
 212                 if (count) {
 213                         /* Not the last packet in this batch */
 214                         clone = skb_clone(buf, GFP_ATOMIC);
 215                         if (!clone)
 216                                 goto error;
 217
 218                         skb_trim(clone, packet_len);
 219                         usbnet_skb_return(dev, clone);
 220
 221                         skb_pull(buf, (packet_len + 3) & ~3);
 222                 } else {
 223                         skb_trim(buf, packet_len);
 224
 225                         if (s->current_rx_buf) {
 226                                 usbnet_skb_return(dev, buf);
 227                                 s->current_rx_buf = NULL;
 228                                 return 0;
 229                         }
 230
 231                         return 1;
 232                 }
 233         }
 234
 235 error:
 236         if (s->current_rx_buf) {
 237                 dev_kfree_skb_any(s->current_rx_buf);
 238                 s->current_rx_buf = NULL;
 239         }
 240         dev->net->stats.rx_errors++;
 241         return 0;
 242 }
 243
 244 static struct sk_buff *vl600_tx_fixup(struct usbnet *dev,
 245                 struct sk_buff *skb, gfp_t flags)
 246 {
 247         struct sk_buff *ret;
 248         struct vl600_frame_hdr *frame;
 249         struct vl600_pkt_hdr *packet;
 250         static uint32_t serial = 1;
 251         int orig_len = skb->len - sizeof(struct ethhdr);
 252         int full_len = (skb->len + sizeof(struct vl600_frame_hdr) + 3) & ~3;
 253
 254         frame = (struct vl600_frame_hdr *) skb->data;
 255         if (skb->len > sizeof(*frame) && skb->len == le32_to_cpup(&frame->len))
 256                 return skb; /* Already encapsulated? */
 257
 258         if (skb->len < sizeof(struct ethhdr))
 259                 /* Drop, device can only deal with ethernet packets */
 260                 return NULL;
 261
 262         if (!skb_cloned(skb)) {
 263                 int headroom = skb_headroom(skb);
 264                 int tailroom = skb_tailroom(skb);
 265
 266                 if (tailroom >= full_len - skb->len - sizeof(*frame) &&
 267                                 headroom >= sizeof(*frame))
 268                         /* There's enough head and tail room */
 269                         goto encapsulate;
 270
 271                 if (headroom + tailroom + skb->len >= full_len) {
 272                         /* There's enough total room, just readjust */
 273                         skb->data = memmove(skb->head + sizeof(*frame),
 274                                         skb->data, skb->len);
 275                         skb_set_tail_pointer(skb, skb->len);
 276                         goto encapsulate;
 277                 }
 278         }
 279
 280         /* Alloc a new skb with the required size */
 281         ret = skb_copy_expand(skb, sizeof(struct vl600_frame_hdr), full_len -
 282                         skb->len - sizeof(struct vl600_frame_hdr), flags);
 283         dev_kfree_skb_any(skb);
 284         if (!ret)
 285                 return ret;
 286         skb = ret;
 287
 288 encapsulate:
 289         /* Packet header is same size as ethernet packet header
 290          * (sizeof(*packet) == sizeof(struct ethhdr)), additionally the
 291          * h_proto field is in the same place so we just leave it alone and
 292          * overwrite the remaining fields.
 293          */
 294         packet = (struct vl600_pkt_hdr *) skb->data;
 295         /* The VL600 wants IPv6 packets to have an IPv4 ethertype
 296          * Since this modem only supports IPv4 and IPv6, just set all
 297          * frames to 0x0800 (ETH_P_IP)
 298          */
 299         packet->h_proto = htons(ETH_P_IP);
 300         memset(&packet->dummy, 0, sizeof(packet->dummy));
 301         packet->len = cpu_to_le32(orig_len);
 302
 303         frame = skb_push(skb, sizeof(*frame));
 304         memset(frame, 0, sizeof(*frame));
 305         frame->len = cpu_to_le32(full_len);
 306         frame->serial = cpu_to_le32(serial++);
 307         frame->pkt_cnt = cpu_to_le32(1);
 308
 309         if (skb->len < full_len) /* Pad */
 310                 skb_put(skb, full_len - skb->len);
 311
 312         return skb;
 313 }
 314
 315 static const struct driver_info vl600_info = {
 316         .description    = "LG VL600 modem",
 317         .flags          = FLAG_RX_ASSEMBLE | FLAG_WWAN,
 318         .bind           = vl600_bind,
 319         .unbind         = vl600_unbind,
 320         .status         = usbnet_cdc_status,
 321         .rx_fixup       = vl600_rx_fixup,
 322         .tx_fixup       = vl600_tx_fixup,
 323 };
 324
 325 static const struct usb_device_id products[] = {
 326         {
 327                 USB_DEVICE_AND_INTERFACE_INFO(0x1004, 0x61aa, USB_CLASS_COMM,
 328                                 USB_CDC_SUBCLASS_ETHERNET, USB_CDC_PROTO_NONE),
 329                 .driver_info    = (unsigned long) &vl600_info,
 330         },
 331         {},     /* End */
 332 };
 333 MODULE_DEVICE_TABLE(usb, products);
 334
 335 static struct usb_driver lg_vl600_driver = {
 336         .name           = "lg-vl600",
 337         .id_table       = products,
 338         .probe          = usbnet_probe,
 339         .disconnect     = usbnet_disconnect,
 340         .suspend        = usbnet_suspend,
 341         .resume         = usbnet_resume,
 342         .disable_hub_initiated_lpm = 1,
 343 };
 344
 345 module_usb_driver(lg_vl600_driver);
 346
 347 MODULE_AUTHOR("Anrzej Zaborowski");
 348 MODULE_DESCRIPTION("LG-VL600 modem's ethernet link");
 349 MODULE_LICENSE("GPL");