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
  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(&ethhdr->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");