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                 return status;
  88
  89         /* no jumbogram (16K) support for now */
  90
  91         dev->net->hard_header_len += EEM_HEAD + ETH_FCS_LEN + VLAN_HLEN;
  92         dev->hard_mtu = dev->net->mtu + dev->net->hard_header_len;
  93
  94         return 0;
  95 }
  96
  97 /*
  98  * EEM permits packing multiple Ethernet frames into USB transfers
  99  * (a "bundle"), but for TX we don't try to do that.
 100  */
 101 static struct sk_buff *eem_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
 102                                        gfp_t flags)
 103 {
 104         struct sk_buff  *skb2 = NULL;
 105         u16             len = skb->len;
 106         u32             crc = 0;
 107         int             padlen = 0;
 108
 109         /* When ((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket) is
 110          * zero, stick two bytes of zero length EEM packet on the end.
 111          * Else the framework would add invalid single byte padding,
 112          * since it can't know whether ZLPs will be handled right by
 113          * all the relevant hardware and software.
 114          */
 115         if (!((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket))
 116                 padlen += 2;
 117
 118         if (!skb_cloned(skb)) {
 119                 int     headroom = skb_headroom(skb);
 120                 int     tailroom = skb_tailroom(skb);
 121
 122                 if ((tailroom >= ETH_FCS_LEN + padlen) &&
 123                     (headroom >= EEM_HEAD))
 124                         goto done;
 125
 126                 if ((headroom + tailroom)
 127                                 > (EEM_HEAD + ETH_FCS_LEN + padlen)) {
 128                         skb->data = memmove(skb->head +
 129                                         EEM_HEAD,
 130                                         skb->data,
 131                                         skb->len);
 132                         skb_set_tail_pointer(skb, len);
 133                         goto done;
 134                 }
 135         }
 136
 137         skb2 = skb_copy_expand(skb, EEM_HEAD, ETH_FCS_LEN + padlen, flags);
 138         if (!skb2)
 139                 return NULL;
 140
 141         dev_kfree_skb_any(skb);
 142         skb = skb2;
 143
 144 done:
 145         /* we don't use the "no Ethernet CRC" option */
 146         crc = crc32_le(~0, skb->data, skb->len);
 147         crc = ~crc;
 148
 149         put_unaligned_le32(crc, skb_put(skb, 4));
 150
 151         /* EEM packet header format:
 152          * b0..13:      length of ethernet frame
 153          * b14:         bmCRC (1 == valid Ethernet CRC)
 154          * b15:         bmType (0 == data)
 155          */
 156         len = skb->len;
 157         put_unaligned_le16(BIT(14) | len, skb_push(skb, 2));
 158
 159         /* Bundle a zero length EEM packet if needed */
 160         if (padlen)
 161                 put_unaligned_le16(0, skb_put(skb, 2));
 162
 163         return skb;
 164 }
 165
 166 static int eem_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 167 {
 168         /*
 169          * Our task here is to strip off framing, leaving skb with one
 170          * data frame for the usbnet framework code to process.  But we
 171          * may have received multiple EEM payloads, or command payloads.
 172          * So we must process _everything_ as if it's a header, except
 173          * maybe the last data payload
 174          *
 175          * REVISIT the framework needs updating so that when we consume
 176          * all payloads (the last or only message was a command, or a
 177          * zero length EEM packet) that is not accounted as an rx_error.
 178          */
 179         do {
 180                 struct sk_buff  *skb2 = NULL;
 181                 u16             header;
 182                 u16             len = 0;
 183
 184                 /* incomplete EEM header? */
 185                 if (skb->len < EEM_HEAD)
 186                         return 0;
 187
 188                 /*
 189                  * EEM packet header format:
 190                  * b0..14:      EEM type dependent (Data or Command)
 191                  * b15:         bmType
 192                  */
 193                 header = get_unaligned_le16(skb->data);
 194                 skb_pull(skb, EEM_HEAD);
 195
 196                 /*
 197                  * The bmType bit helps to denote when EEM
 198                  * packet is data or command :
 199                  *      bmType = 0      : EEM data payload
 200                  *      bmType = 1      : EEM (link) command
 201                  */
 202                 if (header & BIT(15)) {
 203                         u16     bmEEMCmd;
 204
 205                         /*
 206                          * EEM (link) command packet:
 207                          * b0..10:      bmEEMCmdParam
 208                          * b11..13:     bmEEMCmd
 209                          * b14:         bmReserved (must be 0)
 210                          * b15:         1 (EEM command)
 211                          */
 212                         if (header & BIT(14)) {
 213                                 netdev_dbg(dev->net, "reserved command %04x\n",
 214                                            header);
 215                                 continue;
 216                         }
 217
 218                         bmEEMCmd = (header >> 11) & 0x7;
 219                         switch (bmEEMCmd) {
 220
 221                         /* Responding to echo requests is mandatory. */
 222                         case 0:         /* Echo command */
 223                                 len = header & 0x7FF;
 224
 225                                 /* bogus command? */
 226                                 if (skb->len < len)
 227                                         return 0;
 228
 229                                 skb2 = skb_clone(skb, GFP_ATOMIC);
 230                                 if (unlikely(!skb2))
 231                                         goto next;
 232                                 skb_trim(skb2, len);
 233                                 put_unaligned_le16(BIT(15) | (1 << 11) | len,
 234                                                 skb_push(skb2, 2));
 235                                 eem_linkcmd(dev, skb2);
 236                                 break;
 237
 238                         /*
 239                          * Host may choose to ignore hints.
 240                          *  - suspend: peripheral ready to suspend
 241                          *  - response: suggest N millisec polling
 242                          *  - response complete: suggest N sec polling
 243                          *
 244                          * Suspend is reported and maybe heeded.
 245                          */
 246                         case 2:         /* Suspend hint */
 247                                 usbnet_device_suggests_idle(dev);
 248                                 continue;
 249                         case 3:         /* Response hint */
 250                         case 4:         /* Response complete hint */
 251                                 continue;
 252
 253                         /*
 254                          * Hosts should never receive host-to-peripheral
 255                          * or reserved command codes; or responses to an
 256                          * echo command we didn't send.
 257                          */
 258                         case 1:         /* Echo response */
 259                         case 5:         /* Tickle */
 260                         default:        /* reserved */
 261                                 netdev_warn(dev->net,
 262                                             "unexpected link command %d\n",
 263                                             bmEEMCmd);
 264                                 continue;
 265                         }
 266
 267                 } else {
 268                         u32     crc, crc2;
 269                         int     is_last;
 270
 271                         /* zero length EEM packet? */
 272                         if (header == 0)
 273                                 continue;
 274
 275                         /*
 276                          * EEM data packet header :
 277                          * b0..13:      length of ethernet frame
 278                          * b14:         bmCRC
 279                          * b15:         0 (EEM data)
 280                          */
 281                         len = header & 0x3FFF;
 282
 283                         /* bogus EEM payload? */
 284                         if (skb->len < len)
 285                                 return 0;
 286
 287                         /* bogus ethernet frame? */
 288                         if (len < (ETH_HLEN + ETH_FCS_LEN))
 289                                 goto next;
 290
 291                         /*
 292                          * Treat the last payload differently: framework
 293                          * code expects our "fixup" to have stripped off
 294                          * headers, so "skb" is a data packet (or error).
 295                          * Else if it's not the last payload, keep "skb"
 296                          * for further processing.
 297                          */
 298                         is_last = (len == skb->len);
 299                         if (is_last)
 300                                 skb2 = skb;
 301                         else {
 302                                 skb2 = skb_clone(skb, GFP_ATOMIC);
 303                                 if (unlikely(!skb2))
 304                                         return 0;
 305                         }
 306
 307                         /*
 308                          * The bmCRC helps to denote when the CRC field in
 309                          * the Ethernet frame contains a calculated CRC:
 310                          *      bmCRC = 1       : CRC is calculated
 311                          *      bmCRC = 0       : CRC = 0xDEADBEEF
 312                          */
 313                         if (header & BIT(14)) {
 314                                 crc = get_unaligned_le32(skb2->data
 315                                                 + len - ETH_FCS_LEN);
 316                                 crc2 = ~crc32_le(~0, skb2->data, skb2->len
 317                                                 - ETH_FCS_LEN);
 318                         } else {
 319                                 crc = get_unaligned_be32(skb2->data
 320                                                 + len - ETH_FCS_LEN);
 321                                 crc2 = 0xdeadbeef;
 322                         }
 323                         skb_trim(skb2, len - ETH_FCS_LEN);
 324
 325                         if (is_last)
 326                                 return crc == crc2;
 327
 328                         if (unlikely(crc != crc2)) {
 329                                 dev->net->stats.rx_errors++;
 330                                 dev_kfree_skb_any(skb2);
 331                         } else
 332                                 usbnet_skb_return(dev, skb2);
 333                 }
 334
 335 next:
 336                 skb_pull(skb, len);
 337         } while (skb->len);
 338
 339         return 1;
 340 }
 341
 342 static const struct driver_info eem_info = {
 343         .description =  "CDC EEM Device",
 344         .flags =        FLAG_ETHER | FLAG_POINTTOPOINT,
 345         .bind =         eem_bind,
 346         .rx_fixup =     eem_rx_fixup,
 347         .tx_fixup =     eem_tx_fixup,
 348 };
 349
 350 /*-------------------------------------------------------------------------*/
 351
 352 static const struct usb_device_id products[] = {
 353 {
 354         USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_EEM,
 355                         USB_CDC_PROTO_EEM),
 356         .driver_info = (unsigned long) &eem_info,
 357 },
 358 {
 359         /* EMPTY == end of list */
 360 },
 361 };
 362 MODULE_DEVICE_TABLE(usb, products);
 363
 364 static struct usb_driver eem_driver = {
 365         .name =         "cdc_eem",
 366         .id_table =     products,
 367         .probe =        usbnet_probe,
 368         .disconnect =   usbnet_disconnect,
 369         .suspend =      usbnet_suspend,
 370         .resume =       usbnet_resume,
 371         .disable_hub_initiated_lpm = 1,
 372 };
 373
 374 module_usb_driver(eem_driver);
 375
 376 MODULE_AUTHOR("Omar Laazimani <omar.oberthur@gmail.com>");
 377 MODULE_DESCRIPTION("USB CDC EEM");
 378 MODULE_LICENSE("GPL");