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, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23 #include <linux/netdevice.h>
  24 #include <linux/etherdevice.h>
  25 #include <linux/ctype.h>
  26 #include <linux/ethtool.h>
  27 #include <linux/workqueue.h>
  28 #include <linux/mii.h>
  29 #include <linux/usb.h>
  30 #include <linux/crc32.h>
  31 #include <linux/usb/cdc.h>
  32 #include <linux/usb/usbnet.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                 devwarn(dev, "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;
  95
  96         return 0;
  97 }
  98
  99 /*
 100  * EEM permits packing multiple Ethernet frames into USB transfers
 101  * (a "bundle"), but for TX we don't try to do that.
 102  */
 103 static struct sk_buff *eem_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
 104                                        gfp_t flags)
 105 {
 106         struct sk_buff  *skb2 = NULL;
 107         u16             len = skb->len;
 108         u32             crc = 0;
 109         int             padlen = 0;
 110
 111         /* When ((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket) is
 112          * zero, stick two bytes of zero length EEM packet on the end.
 113          * Else the framework would add invalid single byte padding,
 114          * since it can't know whether ZLPs will be handled right by
 115          * all the relevant hardware and software.
 116          */
 117         if (!((len + EEM_HEAD + ETH_FCS_LEN) % dev->maxpacket))
 118                 padlen += 2;
 119
 120         if (!skb_cloned(skb)) {
 121                 int     headroom = skb_headroom(skb);
 122                 int     tailroom = skb_tailroom(skb);
 123
 124                 if ((tailroom >= ETH_FCS_LEN + padlen)
 125                                 && (headroom >= EEM_HEAD))
 126                         goto done;
 127
 128                 if ((headroom + tailroom)
 129                                 > (EEM_HEAD + ETH_FCS_LEN + padlen)) {
 130                         skb->data = memmove(skb->head +
 131                                         EEM_HEAD,
 132                                         skb->data,
 133                                         skb->len);
 134                         skb_set_tail_pointer(skb, len);
 135                         goto done;
 136                 }
 137         }
 138
 139         skb2 = skb_copy_expand(skb, EEM_HEAD, ETH_FCS_LEN + padlen, flags);
 140         if (!skb2)
 141                 return NULL;
 142
 143         dev_kfree_skb_any(skb);
 144         skb = skb2;
 145
 146 done:
 147         /* we don't use the "no Ethernet CRC" option */
 148         crc = crc32_le(~0, skb->data, skb->len);
 149         crc = ~crc;
 150
 151         put_unaligned_le32(crc, skb_put(skb, 4));
 152
 153         /* EEM packet header format:
 154          * b0..13:      length of ethernet frame
 155          * b14:         bmCRC (1 == valid Ethernet CRC)
 156          * b15:         bmType (0 == data)
 157          */
 158         len = skb->len;
 159         put_unaligned_le16(BIT(14) | len, skb_push(skb, 2));
 160
 161         /* Bundle a zero length EEM packet if needed */
 162         if (padlen)
 163                 put_unaligned_le16(0, skb_put(skb, 2));
 164
 165         return skb;
 166 }
 167
 168 static int eem_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 169 {
 170         /*
 171          * Our task here is to strip off framing, leaving skb with one
 172          * data frame for the usbnet framework code to process.  But we
 173          * may have received multiple EEM payloads, or command payloads.
 174          * So we must process _everything_ as if it's a header, except
 175          * maybe the last data payload
 176          *
 177          * REVISIT the framework needs updating so that when we consume
 178          * all payloads (the last or only message was a command, or a
 179          * zero length EEM packet) that is not accounted as an rx_error.
 180          */
 181         do {
 182                 struct sk_buff  *skb2 = NULL;
 183                 u16             header;
 184                 u16             len = 0;
 185
 186                 /* incomplete EEM header? */
 187                 if (skb->len < EEM_HEAD)
 188                         return 0;
 189
 190                 /*
 191                  * EEM packet header format:
 192                  * b0..14:      EEM type dependant (Data or Command)
 193                  * b15:         bmType
 194                  */
 195                 header = get_unaligned_le16(skb->data);
 196                 skb_pull(skb, EEM_HEAD);
 197
 198                 /*
 199                  * The bmType bit helps to denote when EEM
 200                  * packet is data or command :
 201                  *      bmType = 0      : EEM data payload
 202                  *      bmType = 1      : EEM (link) command
 203                  */
 204                 if (header & BIT(15)) {
 205                         u16     bmEEMCmd;
 206
 207                         /*
 208                          * EEM (link) command packet:
 209                          * b0..10:      bmEEMCmdParam
 210                          * b11..13:     bmEEMCmd
 211                          * b14:         bmReserved (must be 0)
 212                          * b15:         1 (EEM command)
 213                          */
 214                         if (header & BIT(14)) {
 215                                 devdbg(dev, "reserved command %04x\n", header);
 216                                 continue;
 217                         }
 218
 219                         bmEEMCmd = (header >> 11) & 0x7;
 220                         switch (bmEEMCmd) {
 221
 222                         /* Responding to echo requests is mandatory. */
 223                         case 0:         /* Echo command */
 224                                 len = header & 0x7FF;
 225
 226                                 /* bogus command? */
 227                                 if (skb->len < len)
 228                                         return 0;
 229
 230                                 skb2 = skb_clone(skb, GFP_ATOMIC);
 231                                 if (unlikely(!skb2))
 232                                         goto next;
 233                                 skb_trim(skb2, len);
 234                                 put_unaligned_le16(BIT(15) | (1 << 11) | len,
 235                                                 skb_push(skb2, 2));
 236                                 eem_linkcmd(dev, skb2);
 237                                 break;
 238
 239                         /*
 240                          * Host may choose to ignore hints.
 241                          *  - suspend: peripheral ready to suspend
 242                          *  - response: suggest N millisec polling
 243                          *  - response complete: suggest N sec polling
 244                          */
 245                         case 2:         /* Suspend hint */
 246                         case 3:         /* Response hint */
 247                         case 4:         /* Response complete hint */
 248                                 continue;
 249
 250                         /*
 251                          * Hosts should never receive host-to-peripheral
 252                          * or reserved command codes; or responses to an
 253                          * echo command we didn't send.
 254                          */
 255                         case 1:         /* Echo response */
 256                         case 5:         /* Tickle */
 257                         default:        /* reserved */
 258                                 devwarn(dev, "unexpected link command %d\n",
 259                                                 bmEEMCmd);
 260                                 continue;
 261                         }
 262
 263                 } else {
 264                         u32     crc, crc2;
 265                         int     is_last;
 266
 267                         /* zero length EEM packet? */
 268                         if (header == 0)
 269                                 continue;
 270
 271                         /*
 272                          * EEM data packet header :
 273                          * b0..13:      length of ethernet frame
 274                          * b14:         bmCRC
 275                          * b15:         0 (EEM data)
 276                          */
 277                         len = header & 0x3FFF;
 278
 279                         /* bogus EEM payload? */
 280                         if (skb->len < len)
 281                                 return 0;
 282
 283                         /* bogus ethernet frame? */
 284                         if (len < (ETH_HLEN + ETH_FCS_LEN))
 285                                 goto next;
 286
 287                         /*
 288                          * Treat the last payload differently: framework
 289                          * code expects our "fixup" to have stripped off
 290                          * headers, so "skb" is a data packet (or error).
 291                          * Else if it's not the last payload, keep "skb"
 292                          * for further processing.
 293                          */
 294                         is_last = (len == skb->len);
 295                         if (is_last)
 296                                 skb2 = skb;
 297                         else {
 298                                 skb2 = skb_clone(skb, GFP_ATOMIC);
 299                                 if (unlikely(!skb2))
 300                                         return 0;
 301                         }
 302
 303                         crc = get_unaligned_le32(skb2->data
 304                                         + len - ETH_FCS_LEN);
 305                         skb_trim(skb2, len - ETH_FCS_LEN);
 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                                 crc2 = ~crc32_le(~0, skb2->data, len);
 315                         else
 316                                 crc2 = 0xdeadbeef;
 317
 318                         if (is_last)
 319                                 return crc == crc2;
 320
 321                         if (unlikely(crc != crc2)) {
 322                                 dev->net->stats.rx_errors++;
 323                                 dev_kfree_skb_any(skb2);
 324                         } else
 325                                 usbnet_skb_return(dev, skb2);
 326                 }
 327
 328 next:
 329                 skb_pull(skb, len);
 330         } while (skb->len);
 331
 332         return 1;
 333 }
 334
 335 static const struct driver_info eem_info = {
 336         .description =  "CDC EEM Device",
 337         .flags =        FLAG_ETHER,
 338         .bind =         eem_bind,
 339         .rx_fixup =     eem_rx_fixup,
 340         .tx_fixup =     eem_tx_fixup,
 341 };
 342
 343 /*-------------------------------------------------------------------------*/
 344
 345 static const struct usb_device_id products[] = {
 346 {
 347         USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_EEM,
 348                         USB_CDC_PROTO_EEM),
 349         .driver_info = (unsigned long) &eem_info,
 350 },
 351 {
 352         /* EMPTY == end of list */
 353 },
 354 };
 355 MODULE_DEVICE_TABLE(usb, products);
 356
 357 static struct usb_driver eem_driver = {
 358         .name =         "cdc_eem",
 359         .id_table =     products,
 360         .probe =        usbnet_probe,
 361         .disconnect =   usbnet_disconnect,
 362         .suspend =      usbnet_suspend,
 363         .resume =       usbnet_resume,
 364 };
 365
 366
 367 static int __init eem_init(void)
 368 {
 369         return usb_register(&eem_driver);
 370 }
 371 module_init(eem_init);
 372
 373 static void __exit eem_exit(void)
 374 {
 375         usb_deregister(&eem_driver);
 376 }
 377 module_exit(eem_exit);
 378
 379 MODULE_AUTHOR("Omar Laazimani <omar.oberthur@gmail.com>");
 380 MODULE_DESCRIPTION("USB CDC EEM");
 381 MODULE_LICENSE("GPL");