drivers/media/usb/em28xx/em28xx-i2c.c

   1 /*
   2    em28xx-i2c.c - driver for Empia EM2800/EM2820/2840 USB video capture devices
   3
   4    Copyright (C) 2005 Ludovico Cavedon <cavedon@sssup.it>
   5                       Markus Rechberger <mrechberger@gmail.com>
   6                       Mauro Carvalho Chehab <mchehab@infradead.org>
   7                       Sascha Sommer <saschasommer@freenet.de>
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22  */
  23
  24 #include <linux/module.h>
  25 #include <linux/kernel.h>
  26 #include <linux/usb.h>
  27 #include <linux/i2c.h>
  28
  29 #include "em28xx.h"
  30 #include "tuner-xc2028.h"
  31 #include <media/v4l2-common.h>
  32 #include <media/tuner.h>
  33
  34 /* ----------------------------------------------------------- */
  35
  36 static unsigned int i2c_scan;
  37 module_param(i2c_scan, int, 0444);
  38 MODULE_PARM_DESC(i2c_scan, "scan i2c bus at insmod time");
  39
  40 static unsigned int i2c_debug;
  41 module_param(i2c_debug, int, 0644);
  42 MODULE_PARM_DESC(i2c_debug, "enable debug messages [i2c]");
  43
  44 /*
  45  * em2800_i2c_send_bytes()
  46  * send up to 4 bytes to the em2800 i2c device
  47  */
  48 static int em2800_i2c_send_bytes(struct em28xx *dev, u8 addr, u8 *buf, u16 len)
  49 {
  50         int ret;
  51         int write_timeout;
  52         u8 b2[6];
  53
  54         if (len < 1 || len > 4)
  55                 return -EOPNOTSUPP;
  56
  57         BUG_ON(len < 1 || len > 4);
  58         b2[5] = 0x80 + len - 1;
  59         b2[4] = addr;
  60         b2[3] = buf[0];
  61         if (len > 1)
  62                 b2[2] = buf[1];
  63         if (len > 2)
  64                 b2[1] = buf[2];
  65         if (len > 3)
  66                 b2[0] = buf[3];
  67
  68         /* trigger write */
  69         ret = dev->em28xx_write_regs(dev, 4 - len, &b2[4 - len], 2 + len);
  70         if (ret != 2 + len) {
  71                 em28xx_warn("failed to trigger write to i2c address 0x%x "
  72                             "(error=%i)\n", addr, ret);
  73                 return (ret < 0) ? ret : -EIO;
  74         }
  75         /* wait for completion */
  76         for (write_timeout = EM2800_I2C_XFER_TIMEOUT; write_timeout > 0;
  77              write_timeout -= 5) {
  78                 ret = dev->em28xx_read_reg(dev, 0x05);
  79                 if (ret == 0x80 + len - 1) {
  80                         return len;
  81                 } else if (ret == 0x94 + len - 1) {
  82                         return -ENODEV;
  83                 } else if (ret < 0) {
  84                         em28xx_warn("failed to get i2c transfer status from "
  85                                     "bridge register (error=%i)\n", ret);
  86                         return ret;
  87                 }
  88                 msleep(5);
  89         }
  90         em28xx_warn("write to i2c device at 0x%x timed out\n", addr);
  91         return -EIO;
  92 }
  93
  94 /*
  95  * em2800_i2c_recv_bytes()
  96  * read up to 4 bytes from the em2800 i2c device
  97  */
  98 static int em2800_i2c_recv_bytes(struct em28xx *dev, u8 addr, u8 *buf, u16 len)
  99 {
 100         u8 buf2[4];
 101         int ret;
 102         int read_timeout;
 103         int i;
 104
 105         if (len < 1 || len > 4)
 106                 return -EOPNOTSUPP;
 107
 108         /* trigger read */
 109         buf2[1] = 0x84 + len - 1;
 110         buf2[0] = addr;
 111         ret = dev->em28xx_write_regs(dev, 0x04, buf2, 2);
 112         if (ret != 2) {
 113                 em28xx_warn("failed to trigger read from i2c address 0x%x "
 114                             "(error=%i)\n", addr, ret);
 115                 return (ret < 0) ? ret : -EIO;
 116         }
 117
 118         /* wait for completion */
 119         for (read_timeout = EM2800_I2C_XFER_TIMEOUT; read_timeout > 0;
 120              read_timeout -= 5) {
 121                 ret = dev->em28xx_read_reg(dev, 0x05);
 122                 if (ret == 0x84 + len - 1) {
 123                         break;
 124                 } else if (ret == 0x94 + len - 1) {
 125                         return -ENODEV;
 126                 } else if (ret < 0) {
 127                         em28xx_warn("failed to get i2c transfer status from "
 128                                     "bridge register (error=%i)\n", ret);
 129                         return ret;
 130                 }
 131                 msleep(5);
 132         }
 133         if (ret != 0x84 + len - 1)
 134                 em28xx_warn("read from i2c device at 0x%x timed out\n", addr);
 135
 136         /* get the received message */
 137         ret = dev->em28xx_read_reg_req_len(dev, 0x00, 4-len, buf2, len);
 138         if (ret != len) {
 139                 em28xx_warn("reading from i2c device at 0x%x failed: "
 140                             "couldn't get the received message from the bridge "
 141                             "(error=%i)\n", addr, ret);
 142                 return (ret < 0) ? ret : -EIO;
 143         }
 144         for (i = 0; i < len; i++)
 145                 buf[i] = buf2[len - 1 - i];
 146
 147         return ret;
 148 }
 149
 150 /*
 151  * em2800_i2c_check_for_device()
 152  * check if there is an i2c device at the supplied address
 153  */
 154 static int em2800_i2c_check_for_device(struct em28xx *dev, u8 addr)
 155 {
 156         u8 buf;
 157         int ret;
 158
 159         ret = em2800_i2c_recv_bytes(dev, addr, &buf, 1);
 160         if (ret == 1)
 161                 return 0;
 162         return (ret < 0) ? ret : -EIO;
 163 }
 164
 165 /*
 166  * em28xx_i2c_send_bytes()
 167  */
 168 static int em28xx_i2c_send_bytes(struct em28xx *dev, u16 addr, u8 *buf,
 169                                  u16 len, int stop)
 170 {
 171         int write_timeout, ret;
 172
 173         if (len < 1 || len > 64)
 174                 return -EOPNOTSUPP;
 175         /* NOTE: limited by the USB ctrl message constraints
 176          * Zero length reads always succeed, even if no device is connected */
 177
 178         /* Write to i2c device */
 179         ret = dev->em28xx_write_regs_req(dev, stop ? 2 : 3, addr, buf, len);
 180         if (ret != len) {
 181                 if (ret < 0) {
 182                         em28xx_warn("writing to i2c device at 0x%x failed "
 183                                     "(error=%i)\n", addr, ret);
 184                         return ret;
 185                 } else {
 186                         em28xx_warn("%i bytes write to i2c device at 0x%x "
 187                                     "requested, but %i bytes written\n",
 188                                     len, addr, ret);
 189                         return -EIO;
 190                 }
 191         }
 192
 193         /* Check success of the i2c operation */
 194         for (write_timeout = EM2800_I2C_XFER_TIMEOUT; write_timeout > 0;
 195              write_timeout -= 5) {
 196                 ret = dev->em28xx_read_reg(dev, 0x05);
 197                 if (ret == 0) { /* success */
 198                         return len;
 199                 } else if (ret == 0x10) {
 200                         return -ENODEV;
 201                 } else if (ret < 0) {
 202                         em28xx_warn("failed to read i2c transfer status from "
 203                                     "bridge (error=%i)\n", ret);
 204                         return ret;
 205                 }
 206                 msleep(5);
 207                 /* NOTE: do we really have to wait for success ?
 208                    Never seen anything else than 0x00 or 0x10
 209                    (even with high payload) ...                 */
 210         }
 211         em28xx_warn("write to i2c device at 0x%x timed out\n", addr);
 212         return -EIO;
 213 }
 214
 215 /*
 216  * em28xx_i2c_recv_bytes()
 217  * read a byte from the i2c device
 218  */
 219 static int em28xx_i2c_recv_bytes(struct em28xx *dev, u16 addr, u8 *buf, u16 len)
 220 {
 221         int ret;
 222
 223         if (len < 1 || len > 64)
 224                 return -EOPNOTSUPP;
 225         /* NOTE: limited by the USB ctrl message constraints
 226          * Zero length reads always succeed, even if no device is connected */
 227
 228         /* Read data from i2c device */
 229         ret = dev->em28xx_read_reg_req_len(dev, 2, addr, buf, len);
 230         if (ret != len) {
 231                 if (ret < 0) {
 232                         em28xx_warn("reading from i2c device at 0x%x failed "
 233                                     "(error=%i)\n", addr, ret);
 234                         return ret;
 235                 } else {
 236                         em28xx_warn("%i bytes requested from i2c device at "
 237                                     "0x%x, but %i bytes received\n",
 238                                     len, addr, ret);
 239                         return -EIO;
 240                 }
 241         }
 242
 243         /* Check success of the i2c operation */
 244         ret = dev->em28xx_read_reg(dev, 0x05);
 245         if (ret < 0) {
 246                 em28xx_warn("failed to read i2c transfer status from "
 247                             "bridge (error=%i)\n", ret);
 248                 return ret;
 249         }
 250         if (ret > 0) {
 251                 if (ret == 0x10) {
 252                         return -ENODEV;
 253                 } else {
 254                         em28xx_warn("unknown i2c error (status=%i)\n", ret);
 255                         return -EIO;
 256                 }
 257         }
 258         return len;
 259 }
 260
 261 /*
 262  * em28xx_i2c_check_for_device()
 263  * check if there is a i2c_device at the supplied address
 264  */
 265 static int em28xx_i2c_check_for_device(struct em28xx *dev, u16 addr)
 266 {
 267         int ret;
 268         u8 buf;
 269
 270         ret = em28xx_i2c_recv_bytes(dev, addr, &buf, 1);
 271         if (ret == 1)
 272                 return 0;
 273         return (ret < 0) ? ret : -EIO;
 274 }
 275
 276 /*
 277  * em28xx_i2c_xfer()
 278  * the main i2c transfer function
 279  */
 280 static int em28xx_i2c_xfer(struct i2c_adapter *i2c_adap,
 281                            struct i2c_msg msgs[], int num)
 282 {
 283         struct em28xx *dev = i2c_adap->algo_data;
 284         int addr, rc, i, byte;
 285
 286         if (num <= 0)
 287                 return 0;
 288         for (i = 0; i < num; i++) {
 289                 addr = msgs[i].addr << 1;
 290                 if (i2c_debug)
 291                         printk(KERN_DEBUG "%s at %s: %s %s addr=%02x len=%d:",
 292                                dev->name, __func__ ,
 293                                (msgs[i].flags & I2C_M_RD) ? "read" : "write",
 294                                i == num - 1 ? "stop" : "nonstop",
 295                                addr, msgs[i].len);
 296                 if (!msgs[i].len) { /* no len: check only for device presence */
 297                         if (dev->board.is_em2800)
 298                                 rc = em2800_i2c_check_for_device(dev, addr);
 299                         else
 300                                 rc = em28xx_i2c_check_for_device(dev, addr);
 301                         if (rc == -ENODEV) {
 302                                 if (i2c_debug)
 303                                         printk(" no device\n");
 304                                 return rc;
 305                         }
 306                 } else if (msgs[i].flags & I2C_M_RD) {
 307                         /* read bytes */
 308                         if (dev->board.is_em2800)
 309                                 rc = em2800_i2c_recv_bytes(dev, addr,
 310                                                            msgs[i].buf,
 311                                                            msgs[i].len);
 312                         else
 313                                 rc = em28xx_i2c_recv_bytes(dev, addr,
 314                                                            msgs[i].buf,
 315                                                            msgs[i].len);
 316                         if (i2c_debug) {
 317                                 for (byte = 0; byte < msgs[i].len; byte++)
 318                                         printk(" %02x", msgs[i].buf[byte]);
 319                         }
 320                 } else {
 321                         /* write bytes */
 322                         if (i2c_debug) {
 323                                 for (byte = 0; byte < msgs[i].len; byte++)
 324                                         printk(" %02x", msgs[i].buf[byte]);
 325                         }
 326                         if (dev->board.is_em2800)
 327                                 rc = em2800_i2c_send_bytes(dev, addr,
 328                                                            msgs[i].buf,
 329                                                            msgs[i].len);
 330                         else
 331                                 rc = em28xx_i2c_send_bytes(dev, addr,
 332                                                            msgs[i].buf,
 333                                                            msgs[i].len,
 334                                                            i == num - 1);
 335                 }
 336                 if (rc < 0) {
 337                         if (i2c_debug)
 338                                 printk(" ERROR: %i\n", rc);
 339                         return rc;
 340                 }
 341                 if (i2c_debug)
 342                         printk("\n");
 343         }
 344
 345         return num;
 346 }
 347
 348 /* based on linux/sunrpc/svcauth.h and linux/hash.h
 349  * The original hash function returns a different value, if arch is x86_64
 350  *  or i386.
 351  */
 352 static inline unsigned long em28xx_hash_mem(char *buf, int length, int bits)
 353 {
 354         unsigned long hash = 0;
 355         unsigned long l = 0;
 356         int len = 0;
 357         unsigned char c;
 358         do {
 359                 if (len == length) {
 360                         c = (char)len;
 361                         len = -1;
 362                 } else
 363                         c = *buf++;
 364                 l = (l << 8) | c;
 365                 len++;
 366                 if ((len & (32 / 8 - 1)) == 0)
 367                         hash = ((hash^l) * 0x9e370001UL);
 368         } while (len);
 369
 370         return (hash >> (32 - bits)) & 0xffffffffUL;
 371 }
 372
 373 /* Helper function to read data blocks from i2c clients with 8 or 16 bit
 374  * address width, 8 bit register width and auto incrementation been activated */
 375 static int em28xx_i2c_read_block(struct em28xx *dev, u16 addr, bool addr_w16,
 376                                  u16 len, u8 *data)
 377 {
 378         int remain = len, rsize, rsize_max, ret;
 379         u8 buf[2];
 380
 381         /* Sanity check */
 382         if (addr + remain > (addr_w16 * 0xff00 + 0xff + 1))
 383                 return -EINVAL;
 384         /* Select address */
 385         buf[0] = addr >> 8;
 386         buf[1] = addr & 0xff;
 387         ret = i2c_master_send(&dev->i2c_client, buf + !addr_w16, 1 + addr_w16);
 388         if (ret < 0)
 389                 return ret;
 390         /* Read data */
 391         if (dev->board.is_em2800)
 392                 rsize_max = 4;
 393         else
 394                 rsize_max = 64;
 395         while (remain > 0) {
 396                 if (remain > rsize_max)
 397                         rsize = rsize_max;
 398                 else
 399                         rsize = remain;
 400
 401                 ret = i2c_master_recv(&dev->i2c_client, data, rsize);
 402                 if (ret < 0)
 403                         return ret;
 404
 405                 remain -= rsize;
 406                 data += rsize;
 407         }
 408
 409         return len;
 410 }
 411
 412 static int em28xx_i2c_eeprom(struct em28xx *dev, unsigned char **eedata, int len)
 413 {
 414         u8 buf, *data;
 415         struct em28xx_eeprom *em_eeprom;
 416         int i, err;
 417
 418         *eedata = NULL;
 419
 420         dev->i2c_client.addr = 0xa0 >> 1;
 421
 422         /* Check if board has eeprom */
 423         err = i2c_master_recv(&dev->i2c_client, &buf, 0);
 424         if (err < 0) {
 425                 em28xx_info("board has no eeprom\n");
 426                 return -ENODEV;
 427         }
 428
 429         data = kzalloc(len, GFP_KERNEL);
 430         if (data == NULL)
 431                 return -ENOMEM;
 432
 433         /* Read EEPROM content */
 434         err = em28xx_i2c_read_block(dev, 0x0000, dev->eeprom_addrwidth_16bit,
 435                                     len, data);
 436         if (err != len) {
 437                 em28xx_errdev("failed to read eeprom (err=%d)\n", err);
 438                 kfree(data);
 439                 return err;
 440         }
 441
 442         /* Display eeprom content */
 443         for (i = 0; i < len; i++) {
 444                 if (0 == (i % 16)) {
 445                         if (dev->eeprom_addrwidth_16bit)
 446                                 em28xx_info("i2c eeprom %04x:", i);
 447                         else
 448                                 em28xx_info("i2c eeprom %02x:", i);
 449                 }
 450                 printk(" %02x", data[i]);
 451                 if (15 == (i % 16))
 452                         printk("\n");
 453         }
 454
 455         if (dev->eeprom_addrwidth_16bit &&
 456             data[0] == 0x26 && data[3] == 0x00) {
 457                 /* new eeprom format; size 4-64kb */
 458                 dev->hash = em28xx_hash_mem(data, len, 32);
 459                 em28xx_info("EEPROM hash = 0x%08lx\n", dev->hash);
 460                 em28xx_info("EEPROM info: boot page address = 0x%02x04, "
 461                             "boot configuration = 0x%02x\n",
 462                             data[1], data[2]);
 463                 /* boot configuration (address 0x0002):
 464                  * [0]   microcode download speed: 1 = 400 kHz; 0 = 100 kHz
 465                  * [1]   always selects 12 kb RAM
 466                  * [2]   USB device speed: 1 = force Full Speed; 0 = auto detect
 467                  * [4]   1 = force fast mode and no suspend for device testing
 468                  * [5:7] USB PHY tuning registers; determined by device
 469                  *       characterization
 470                  */
 471
 472                 /* FIXME:
 473                  * - read more than 256 bytes / addresses above 0x00ff
 474                  * - find offset for device config dataset and extract it
 475                  * - decrypt eeprom data for camera bridges (em25xx, em276x+)
 476                  * - use separate/different eeprom hashes (not yet used)
 477                  */
 478
 479                 return 0;
 480         } else if (data[0] != 0x1a || data[1] != 0xeb ||
 481                    data[2] != 0x67 || data[3] != 0x95) {
 482                 em28xx_info("unknown eeprom format or eeprom corrupted !\n");
 483                 return -ENODEV;
 484         }
 485
 486         *eedata = data;
 487         em_eeprom = (void *)eedata;
 488
 489         dev->hash = em28xx_hash_mem(data, len, 32);
 490
 491         em28xx_info("EEPROM ID = %02x %02x %02x %02x, EEPROM hash = 0x%08lx\n",
 492                     em_eeprom->id[0], em_eeprom->id[1],
 493                     em_eeprom->id[2], em_eeprom->id[3], dev->hash);
 494
 495         em28xx_info("EEPROM info:\n");
 496
 497         switch (le16_to_cpu(em_eeprom->chip_conf) >> 4 & 0x3) {
 498         case 0:
 499                 em28xx_info("\tNo audio on board.\n");
 500                 break;
 501         case 1:
 502                 em28xx_info("\tAC97 audio (5 sample rates)\n");
 503                 break;
 504         case 2:
 505                 em28xx_info("\tI2S audio, sample rate=32k\n");
 506                 break;
 507         case 3:
 508                 em28xx_info("\tI2S audio, 3 sample rates\n");
 509                 break;
 510         }
 511
 512         if (le16_to_cpu(em_eeprom->chip_conf) & 1 << 3)
 513                 em28xx_info("\tUSB Remote wakeup capable\n");
 514
 515         if (le16_to_cpu(em_eeprom->chip_conf) & 1 << 2)
 516                 em28xx_info("\tUSB Self power capable\n");
 517
 518         switch (le16_to_cpu(em_eeprom->chip_conf) & 0x3) {
 519         case 0:
 520                 em28xx_info("\t500mA max power\n");
 521                 break;
 522         case 1:
 523                 em28xx_info("\t400mA max power\n");
 524                 break;
 525         case 2:
 526                 em28xx_info("\t300mA max power\n");
 527                 break;
 528         case 3:
 529                 em28xx_info("\t200mA max power\n");
 530                 break;
 531         }
 532         em28xx_info("\tTable at offset 0x%02x, strings=0x%04x, 0x%04x, 0x%04x\n",
 533                     em_eeprom->string_idx_table,
 534                     le16_to_cpu(em_eeprom->string1),
 535                     le16_to_cpu(em_eeprom->string2),
 536                     le16_to_cpu(em_eeprom->string3));
 537
 538         return 0;
 539 }
 540
 541 /* ----------------------------------------------------------- */
 542
 543 /*
 544  * functionality()
 545  */
 546 static u32 functionality(struct i2c_adapter *adap)
 547 {
 548         struct em28xx *dev = adap->algo_data;
 549         u32 func_flags = I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 550         if (dev->board.is_em2800)
 551                 func_flags &= ~I2C_FUNC_SMBUS_WRITE_BLOCK_DATA;
 552         return func_flags;
 553 }
 554
 555 static struct i2c_algorithm em28xx_algo = {
 556         .master_xfer   = em28xx_i2c_xfer,
 557         .functionality = functionality,
 558 };
 559
 560 static struct i2c_adapter em28xx_adap_template = {
 561         .owner = THIS_MODULE,
 562         .name = "em28xx",
 563         .algo = &em28xx_algo,
 564 };
 565
 566 static struct i2c_client em28xx_client_template = {
 567         .name = "em28xx internal",
 568 };
 569
 570 /* ----------------------------------------------------------- */
 571
 572 /*
 573  * i2c_devs
 574  * incomplete list of known devices
 575  */
 576 static char *i2c_devs[128] = {
 577         [0x3e >> 1] = "remote IR sensor",
 578         [0x4a >> 1] = "saa7113h",
 579         [0x52 >> 1] = "drxk",
 580         [0x60 >> 1] = "remote IR sensor",
 581         [0x8e >> 1] = "remote IR sensor",
 582         [0x86 >> 1] = "tda9887",
 583         [0x80 >> 1] = "msp34xx",
 584         [0x88 >> 1] = "msp34xx",
 585         [0xa0 >> 1] = "eeprom",
 586         [0xb0 >> 1] = "tda9874",
 587         [0xb8 >> 1] = "tvp5150a",
 588         [0xba >> 1] = "webcam sensor or tvp5150a",
 589         [0xc0 >> 1] = "tuner (analog)",
 590         [0xc2 >> 1] = "tuner (analog)",
 591         [0xc4 >> 1] = "tuner (analog)",
 592         [0xc6 >> 1] = "tuner (analog)",
 593 };
 594
 595 /*
 596  * do_i2c_scan()
 597  * check i2c address range for devices
 598  */
 599 void em28xx_do_i2c_scan(struct em28xx *dev)
 600 {
 601         u8 i2c_devicelist[128];
 602         unsigned char buf;
 603         int i, rc;
 604
 605         memset(i2c_devicelist, 0, ARRAY_SIZE(i2c_devicelist));
 606
 607         for (i = 0; i < ARRAY_SIZE(i2c_devs); i++) {
 608                 dev->i2c_client.addr = i;
 609                 rc = i2c_master_recv(&dev->i2c_client, &buf, 0);
 610                 if (rc < 0)
 611                         continue;
 612                 i2c_devicelist[i] = i;
 613                 em28xx_info("found i2c device @ 0x%x [%s]\n",
 614                             i << 1, i2c_devs[i] ? i2c_devs[i] : "???");
 615         }
 616
 617         dev->i2c_hash = em28xx_hash_mem(i2c_devicelist,
 618                                         ARRAY_SIZE(i2c_devicelist), 32);
 619 }
 620
 621 /*
 622  * em28xx_i2c_register()
 623  * register i2c bus
 624  */
 625 int em28xx_i2c_register(struct em28xx *dev)
 626 {
 627         int retval;
 628
 629         BUG_ON(!dev->em28xx_write_regs || !dev->em28xx_read_reg);
 630         BUG_ON(!dev->em28xx_write_regs_req || !dev->em28xx_read_reg_req);
 631         dev->i2c_adap = em28xx_adap_template;
 632         dev->i2c_adap.dev.parent = &dev->udev->dev;
 633         strcpy(dev->i2c_adap.name, dev->name);
 634         dev->i2c_adap.algo_data = dev;
 635         i2c_set_adapdata(&dev->i2c_adap, &dev->v4l2_dev);
 636
 637         retval = i2c_add_adapter(&dev->i2c_adap);
 638         if (retval < 0) {
 639                 em28xx_errdev("%s: i2c_add_adapter failed! retval [%d]\n",
 640                         __func__, retval);
 641                 return retval;
 642         }
 643
 644         dev->i2c_client = em28xx_client_template;
 645         dev->i2c_client.adapter = &dev->i2c_adap;
 646
 647         retval = em28xx_i2c_eeprom(dev, &dev->eedata, 256);
 648         if ((retval < 0) && (retval != -ENODEV)) {
 649                 em28xx_errdev("%s: em28xx_i2_eeprom failed! retval [%d]\n",
 650                         __func__, retval);
 651
 652                 return retval;
 653         }
 654
 655         if (i2c_scan)
 656                 em28xx_do_i2c_scan(dev);
 657
 658         return 0;
 659 }
 660
 661 /*
 662  * em28xx_i2c_unregister()
 663  * unregister i2c_bus
 664  */
 665 int em28xx_i2c_unregister(struct em28xx *dev)
 666 {
 667         i2c_del_adapter(&dev->i2c_adap);
 668         return 0;
 669 }