drivers/net/usb/cdc_eem.c

   1 /*
   2  * USB CDC EEM network interface driver
   3  * Copyright (C) 2009 Oberthur Technologies
   4  * by Omar Laazimani, Olivier Condemine
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <linux/module.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/etherdevice.h>
  23 #include <linux/ctype.h>
  24 #include <linux/ethtool.h>
  25 #include <linux/workqueue.h>
  26 #include <linux/mii.h>
  27 #include <linux/usb.h>
  28 #include <linux/crc32.h>
  29 #include <linux/usb/cdc.h>
  30 #include <linux/usb/usbnet.h>
  31 #include <linux/gfp.h>
  32 #include <linux/if_vlan.h>
  33
  34
  35 /*
  36  * This driver is an implementation of the CDC "Ethernet Emulation
  37  * Model" (EEM) specification, which encapsulates Ethernet frames
  38  * for transport over USB using a simpler USB device model than the
  39  * previous CDC "Ethernet Control Model" (ECM, or "CDC Ethernet").
  40  *
  41  * For details, see www.usb.org/developers/devclass_docs/CDC_EEM10.pdf
  42  *
  43  * This version has been tested with GIGAntIC WuaoW SIM Smart Card on 2.6.24,
  44  * 2.6.27 and 2.6.30rc2 kernel.
  45  * It has also been validated on Openmoko Om 2008.12 (based on 2.6.24 kernel).
  46  * build on 23-April-2009
  47  */
  48
  49 #define EEM_HEAD        2               /* 2 byte header */
  50
  51 /*-------------------------------------------------------------------------*/
  52
  53 static void eem_linkcmd_complete(struct urb *urb)
  54 {
  55         dev_kfree_skb(urb->context);
  56         usb_free_urb(urb);
  57 }
  58
  59 static void eem_linkcmd(struct usbnet *dev, struct sk_buff *skb)
  60 {
  61         struct urb              *urb;
  62         int                     status;
  63
  64         urb = usb_alloc_urb(0, GFP_ATOMIC);
  65         if (!urb)
  66                 goto fail;
  67
  68         usb_fill_bulk_urb(urb, dev->udev, dev->out,
  69                         skb->data, skb->len, eem_linkcmd_complete, skb);
  70
  71         status = usb_submit_urb(urb, GFP_ATOMIC);
  72         if (status) {
  73                 usb_free_urb(urb);
  74 fail:
  75                 dev_kfree_skb(skb);
  76                 netdev_warn(dev->net, "link cmd failure\n");
  77                 return;
  78         }
  79 }
  80
  81 static int eem_bind(struct usbnet *dev, struct usb_interface *intf)
  82 {
  83         int status = 0;
  84
  85         status = usbnet_get_endpoints(dev, intf);
  86         if (status < 0) {
  87                 usb_set_intfdata(intf, NULL);
  88                 usb_driver_release_interface(driver_of(intf), intf);
  89                 return status;
  90         }
  91
  92         /* no jumbogram (16K) support for now */
  93
  94         dev->net->hard_header_len += EEM_HEAD + ETH_FCS_LEN + VLAN_HLEN;
  95         dev->hard_mtu = dev->net->mtu + dev->net->hard_header_len;
  96
  97         return 0;
  98 }
  99
 100 /*
 101  * EEM permits packing multiple Ethernet frames into USB transfers
 102  * (a "bundle"), but for TX we don't try to do that.
 103  */
 104 static struct sk_buff *eem_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
 105                                        gfp_t flags)
 106 {
 107         struct sk_buff  *skb2 = NULL;
 108         u16             len = skb->len;
 109         u32             crc = 0;
 110         int             padlen = 0;
 111
 112         /* When ((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket) is
 113          * zero, stick two bytes of zero length EEM packet on the end.
 114          * Else the framework would add invalid single byte padding,
 115          * since it can't know whether ZLPs will be handled right by
 116          * all the relevant hardware and software.
 117          */
 118         if (!((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket))
 119                 padlen += 2;
 120
 121         if (!skb_cloned(skb)) {
 122                 int     headroom = skb_headroom(skb);
 123                 int     tailroom = skb_tailroom(skb);
 124
 125                 if ((tailroom >= ETH_FCS_LEN + padlen) &&
 126                     (headroom >= EEM_HEAD))
 127                         goto done;
 128
 129                 if ((headroom + tailroom)
 130                                 > (EEM_HEAD + ETH_FCS_LEN + padlen)) {
 131                         skb->data = memmove(skb->head +
 132                                         EEM_HEAD,
 133                                         skb->data,
 134                                         skb->len);
 135                         skb_set_tail_pointer(skb, len);
 136                         goto done;
 137                 }
 138         }
 139
 140         skb2 = skb_copy_expand(skb, EEM_HEAD, ETH_FCS_LEN + padlen, flags);
 141         if (!skb2)
 142                 return NULL;
 143
 144         dev_kfree_skb_any(skb);
 145         skb = skb2;
 146
 147 done:
 148         /* we don't use the "no Ethernet CRC" option */
 149         crc = crc32_le(~0, skb->data, skb->len);
 150         crc = ~crc;
 151
 152         put_unaligned_le32(crc, skb_put(skb, 4));
 153
 154         /* EEM packet header format:
 155          * b0..13:      length of ethernet frame
 156          * b14:         bmCRC (1 == valid Ethernet CRC)
 157          * b15:         bmType (0 == data)
 158          */
 159         len = skb->len;
 160         put_unaligned_le16(BIT(14) | len, skb_push(skb, 2));
 161
 162         /* Bundle a zero length EEM packet if needed */
 163         if (padlen)
 164                 put_unaligned_le16(0, skb_put(skb, 2));
 165
 166         return skb;
 167 }
 168
 169 static int eem_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 170 {
 171         /*
 172          * Our task here is to strip off framing, leaving skb with one
 173          * data frame for the usbnet framework code to process.  But we
 174          * may have received multiple EEM payloads, or command payloads.
 175          * So we must process _everything_ as if it's a header, except
 176          * maybe the last data payload
 177          *
 178          * REVISIT the framework needs updating so that when we consume
 179          * all payloads (the last or only message was a command, or a
 180          * zero length EEM packet) that is not accounted as an rx_error.
 181          */
 182         do {
 183                 struct sk_buff  *skb2 = NULL;
 184                 u16             header;
 185                 u16             len = 0;
 186
 187                 /* incomplete EEM header? */
 188                 if (skb->len < EEM_HEAD)
 189                         return 0;
 190
 191                 /*
 192                  * EEM packet header format:
 193                  * b0..14:      EEM type dependent (Data or Command)
 194                  * b15:         bmType
 195                  */
 196                 header = get_unaligned_le16(skb->data);
 197                 skb_pull(skb, EEM_HEAD);
 198
 199                 /*
 200                  * The bmType bit helps to denote when EEM
 201                  * packet is data or command :
 202                  *      bmType = 0      : EEM data payload
 203                  *      bmType = 1      : EEM (link) command
 204                  */
 205                 if (header & BIT(15)) {
 206                         u16     bmEEMCmd;
 207
 208                         /*
 209                          * EEM (link) command packet:
 210                          * b0..10:      bmEEMCmdParam
 211                          * b11..13:     bmEEMCmd
 212                          * b14:         bmReserved (must be 0)
 213                          * b15:         1 (EEM command)
 214                          */
 215                         if (header & BIT(14)) {
 216                                 netdev_dbg(dev->net, "reserved command %04x\n",
 217                                            header);
 218                                 continue;
 219                         }
 220
 221                         bmEEMCmd = (header >> 11) & 0x7;
 222                         switch (bmEEMCmd) {
 223
 224                         /* Responding to echo requests is mandatory. */
 225                         case 0:         /* Echo command */
 226                                 len = header & 0x7FF;
 227
 228                                 /* bogus command? */
 229                                 if (skb->len < len)
 230                                         return 0;
 231
 232                                 skb2 = skb_clone(skb, GFP_ATOMIC);
 233                                 if (unlikely(!skb2))
 234                                         goto next;
 235                                 skb_trim(skb2, len);
 236                                 put_unaligned_le16(BIT(15) | (1 << 11) | len,
 237                                                 skb_push(skb2, 2));
 238                                 eem_linkcmd(dev, skb2);
 239                                 break;
 240
 241                         /*
 242                          * Host may choose to ignore hints.
 243                          *  - suspend: peripheral ready to suspend
 244                          *  - response: suggest N millisec polling
 245                          *  - response complete: suggest N sec polling
 246                          *
 247                          * Suspend is reported and maybe heeded.
 248                          */
 249                         case 2:         /* Suspend hint */
 250                                 usbnet_device_suggests_idle(dev);
 251                                 continue;
 252                         case 3:         /* Response hint */
 253                         case 4:         /* Response complete hint */
 254                                 continue;
 255
 256                         /*
 257                          * Hosts should never receive host-to-peripheral
 258                          * or reserved command codes; or responses to an
 259                          * echo command we didn't send.
 260                          */
 261                         case 1:         /* Echo response */
 262                         case 5:         /* Tickle */
 263                         default:        /* reserved */
 264                                 netdev_warn(dev->net,
 265                                             "unexpected link command %d\n",
 266                                             bmEEMCmd);
 267                                 continue;
 268                         }
 269
 270                 } else {
 271                         u32     crc, crc2;
 272                         int     is_last;
 273
 274                         /* zero length EEM packet? */
 275                         if (header == 0)
 276                                 continue;
 277
 278                         /*
 279                          * EEM data packet header :
 280                          * b0..13:      length of ethernet frame
 281                          * b14:         bmCRC
 282                          * b15:         0 (EEM data)
 283                          */
 284                         len = header & 0x3FFF;
 285
 286                         /* bogus EEM payload? */
 287                         if (skb->len < len)
 288                                 return 0;
 289
 290                         /* bogus ethernet frame? */
 291                         if (len < (ETH_HLEN + ETH_FCS_LEN))
 292                                 goto next;
 293
 294                         /*
 295                          * Treat the last payload differently: framework
 296                          * code expects our "fixup" to have stripped off
 297                          * headers, so "skb" is a data packet (or error).
 298                          * Else if it's not the last payload, keep "skb"
 299                          * for further processing.
 300                          */
 301                         is_last = (len == skb->len);
 302                         if (is_last)
 303                                 skb2 = skb;
 304                         else {
 305                                 skb2 = skb_clone(skb, GFP_ATOMIC);
 306                                 if (unlikely(!skb2))
 307                                         return 0;
 308                         }
 309
 310                         /*
 311                          * The bmCRC helps to denote when the CRC field in
 312                          * the Ethernet frame contains a calculated CRC:
 313                          *      bmCRC = 1       : CRC is calculated
 314                          *      bmCRC = 0       : CRC = 0xDEADBEEF
 315                          */
 316                         if (header & BIT(14)) {
 317                                 crc = get_unaligned_le32(skb2->data
 318                                                 + len - ETH_FCS_LEN);
 319                                 crc2 = ~crc32_le(~0, skb2->data, skb2->len
 320                                                 - ETH_FCS_LEN);
 321                         } else {
 322                                 crc = get_unaligned_be32(skb2->data
 323                                                 + len - ETH_FCS_LEN);
 324                                 crc2 = 0xdeadbeef;
 325                         }
 326                         skb_trim(skb2, len - ETH_FCS_LEN);
 327
 328                         if (is_last)
 329                                 return crc == crc2;
 330
 331                         if (unlikely(crc != crc2)) {
 332                                 dev->net->stats.rx_errors++;
 333                                 dev_kfree_skb_any(skb2);
 334                         } else
 335                                 usbnet_skb_return(dev, skb2);
 336                 }
 337
 338 next:
 339                 skb_pull(skb, len);
 340         } while (skb->len);
 341
 342         return 1;
 343 }
 344
 345 static const struct driver_info eem_info = {
 346         .description =  "CDC EEM Device",
 347         .flags =        FLAG_ETHER | FLAG_POINTTOPOINT,
 348         .bind =         eem_bind,
 349         .rx_fixup =     eem_rx_fixup,
 350         .tx_fixup =     eem_tx_fixup,
 351 };
 352
 353 /*-------------------------------------------------------------------------*/
 354
 355 static const struct usb_device_id products[] = {
 356 {
 357         USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_EEM,
 358                         USB_CDC_PROTO_EEM),
 359         .driver_info = (unsigned long) &eem_info,
 360 },
 361 {
 362         /* EMPTY == end of list */
 363 },
 364 };
 365 MODULE_DEVICE_TABLE(usb, products);
 366
 367 static struct usb_driver eem_driver = {
 368         .name =         "cdc_eem",
 369         .id_table =     products,
 370         .probe =        usbnet_probe,
 371         .disconnect =   usbnet_disconnect,
 372         .suspend =      usbnet_suspend,
 373         .resume =       usbnet_resume,
 374         .disable_hub_initiated_lpm = 1,
 375 };
 376
 377 module_usb_driver(eem_driver);
 378
 379 MODULE_AUTHOR("Omar Laazimani <omar.oberthur@gmail.com>");
 380 MODULE_DESCRIPTION("USB CDC EEM");
 381 MODULE_LICENSE("GPL");