drivers/i2c/algos/i2c-algo-bit.c

   1 /* -------------------------------------------------------------------------
   2  * i2c-algo-bit.c i2c driver algorithms for bit-shift adapters
   3  * -------------------------------------------------------------------------
   4  *   Copyright (C) 1995-2000 Simon G. Vogl
   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., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  * ------------------------------------------------------------------------- */
  20
  21 /* With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki
  22    <kmalkki@cc.hut.fi> and Jean Delvare <khali@linux-fr.org> */
  23
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/delay.h>
  27 #include <linux/init.h>
  28 #include <linux/errno.h>
  29 #include <linux/sched.h>
  30 #include <linux/i2c.h>
  31 #include <linux/i2c-algo-bit.h>
  32
  33
  34 /* ----- global defines ----------------------------------------------- */
  35
  36 #ifdef DEBUG
  37 #define bit_dbg(level, dev, format, args...) \
  38         do { \
  39                 if (i2c_debug >= level) \
  40                         dev_dbg(dev, format, ##args); \
  41         } while (0)
  42 #else
  43 #define bit_dbg(level, dev, format, args...) \
  44         do {} while (0)
  45 #endif /* DEBUG */
  46
  47 /* ----- global variables --------------------------------------------- */
  48
  49 static int bit_test;    /* see if the line-setting functions work       */
  50 module_param(bit_test, int, S_IRUGO);
  51 MODULE_PARM_DESC(bit_test, "lines testing - 0 off; 1 report; 2 fail if stuck");
  52
  53 #ifdef DEBUG
  54 static int i2c_debug = 1;
  55 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
  56 MODULE_PARM_DESC(i2c_debug,
  57                  "debug level - 0 off; 1 normal; 2 verbose; 3 very verbose");
  58 #endif
  59
  60 /* --- setting states on the bus with the right timing: --------------- */
  61
  62 #define setsda(adap, val)       adap->setsda(adap->data, val)
  63 #define setscl(adap, val)       adap->setscl(adap->data, val)
  64 #define getsda(adap)            adap->getsda(adap->data)
  65 #define getscl(adap)            adap->getscl(adap->data)
  66
  67 static inline void sdalo(struct i2c_algo_bit_data *adap)
  68 {
  69         setsda(adap, 0);
  70         udelay((adap->udelay + 1) / 2);
  71 }
  72
  73 static inline void sdahi(struct i2c_algo_bit_data *adap)
  74 {
  75         setsda(adap, 1);
  76         udelay((adap->udelay + 1) / 2);
  77 }
  78
  79 static inline void scllo(struct i2c_algo_bit_data *adap)
  80 {
  81         setscl(adap, 0);
  82         udelay(adap->udelay / 2);
  83 }
  84
  85 /*
  86  * Raise scl line, and do checking for delays. This is necessary for slower
  87  * devices.
  88  */
  89 static int sclhi(struct i2c_algo_bit_data *adap)
  90 {
  91         unsigned long start;
  92
  93         setscl(adap, 1);
  94
  95         /* Not all adapters have scl sense line... */
  96         if (!adap->getscl)
  97                 goto done;
  98
  99         start = jiffies;
 100         while (!getscl(adap)) {
 101                 /* This hw knows how to read the clock line, so we wait
 102                  * until it actually gets high.  This is safer as some
 103                  * chips may hold it low ("clock stretching") while they
 104                  * are processing data internally.
 105                  */
 106                 if (time_after(jiffies, start + adap->timeout))
 107                         return -ETIMEDOUT;
 108                 cond_resched();
 109         }
 110 #ifdef DEBUG
 111         if (jiffies != start && i2c_debug >= 3)
 112                 pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go "
 113                          "high\n", jiffies - start);
 114 #endif
 115
 116 done:
 117         udelay(adap->udelay);
 118         return 0;
 119 }
 120
 121
 122 /* --- other auxiliary functions -------------------------------------- */
 123 static void i2c_start(struct i2c_algo_bit_data *adap)
 124 {
 125         /* assert: scl, sda are high */
 126         setsda(adap, 0);
 127         udelay(adap->udelay);
 128         scllo(adap);
 129 }
 130
 131 static void i2c_repstart(struct i2c_algo_bit_data *adap)
 132 {
 133         /* assert: scl is low */
 134         sdahi(adap);
 135         sclhi(adap);
 136         setsda(adap, 0);
 137         udelay(adap->udelay);
 138         scllo(adap);
 139 }
 140
 141
 142 static void i2c_stop(struct i2c_algo_bit_data *adap)
 143 {
 144         /* assert: scl is low */
 145         sdalo(adap);
 146         sclhi(adap);
 147         setsda(adap, 1);
 148         udelay(adap->udelay);
 149 }
 150
 151
 152
 153 /* send a byte without start cond., look for arbitration,
 154    check ackn. from slave */
 155 /* returns:
 156  * 1 if the device acknowledged
 157  * 0 if the device did not ack
 158  * -ETIMEDOUT if an error occurred (while raising the scl line)
 159  */
 160 static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
 161 {
 162         int i;
 163         int sb;
 164         int ack;
 165         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 166
 167         /* assert: scl is low */
 168         for (i = 7; i >= 0; i--) {
 169                 sb = (c >> i) & 1;
 170                 setsda(adap, sb);
 171                 udelay((adap->udelay + 1) / 2);
 172                 if (sclhi(adap) < 0) { /* timed out */
 173                         bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
 174                                 "timeout at bit #%d\n", (int)c, i);
 175                         return -ETIMEDOUT;
 176                 }
 177                 /* FIXME do arbitration here:
 178                  * if (sb && !getsda(adap)) -> ouch! Get out of here.
 179                  *
 180                  * Report a unique code, so higher level code can retry
 181                  * the whole (combined) message and *NOT* issue STOP.
 182                  */
 183                 scllo(adap);
 184         }
 185         sdahi(adap);
 186         if (sclhi(adap) < 0) { /* timeout */
 187                 bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
 188                         "timeout at ack\n", (int)c);
 189                 return -ETIMEDOUT;
 190         }
 191
 192         /* read ack: SDA should be pulled down by slave, or it may
 193          * NAK (usually to report problems with the data we wrote).
 194          */
 195         ack = !getsda(adap);    /* ack: sda is pulled low -> success */
 196         bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n", (int)c,
 197                 ack ? "A" : "NA");
 198
 199         scllo(adap);
 200         return ack;
 201         /* assert: scl is low (sda undef) */
 202 }
 203
 204
 205 static int i2c_inb(struct i2c_adapter *i2c_adap)
 206 {
 207         /* read byte via i2c port, without start/stop sequence  */
 208         /* acknowledge is sent in i2c_read.                     */
 209         int i;
 210         unsigned char indata = 0;
 211         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 212
 213         /* assert: scl is low */
 214         sdahi(adap);
 215         for (i = 0; i < 8; i++) {
 216                 if (sclhi(adap) < 0) { /* timeout */
 217                         bit_dbg(1, &i2c_adap->dev, "i2c_inb: timeout at bit "
 218                                 "#%d\n", 7 - i);
 219                         return -ETIMEDOUT;
 220                 }
 221                 indata *= 2;
 222                 if (getsda(adap))
 223                         indata |= 0x01;
 224                 setscl(adap, 0);
 225                 udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
 226         }
 227         /* assert: scl is low */
 228         return indata;
 229 }
 230
 231 /*
 232  * Sanity check for the adapter hardware - check the reaction of
 233  * the bus lines only if it seems to be idle.
 234  */
 235 static int test_bus(struct i2c_adapter *i2c_adap)
 236 {
 237         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 238         const char *name = i2c_adap->name;
 239         int scl, sda, ret;
 240
 241         if (adap->pre_xfer) {
 242                 ret = adap->pre_xfer(i2c_adap);
 243                 if (ret < 0)
 244                         return -ENODEV;
 245         }
 246
 247         if (adap->getscl == NULL)
 248                 pr_info("%s: Testing SDA only, SCL is not readable\n", name);
 249
 250         sda = getsda(adap);
 251         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
 252         if (!scl || !sda) {
 253                 printk(KERN_WARNING
 254                        "%s: bus seems to be busy (scl=%d, sda=%d)\n",
 255                        name, scl, sda);
 256                 goto bailout;
 257         }
 258
 259         sdalo(adap);
 260         sda = getsda(adap);
 261         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
 262         if (sda) {
 263                 printk(KERN_WARNING "%s: SDA stuck high!\n", name);
 264                 goto bailout;
 265         }
 266         if (!scl) {
 267                 printk(KERN_WARNING "%s: SCL unexpected low "
 268                        "while pulling SDA low!\n", name);
 269                 goto bailout;
 270         }
 271
 272         sdahi(adap);
 273         sda = getsda(adap);
 274         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
 275         if (!sda) {
 276                 printk(KERN_WARNING "%s: SDA stuck low!\n", name);
 277                 goto bailout;
 278         }
 279         if (!scl) {
 280                 printk(KERN_WARNING "%s: SCL unexpected low "
 281                        "while pulling SDA high!\n", name);
 282                 goto bailout;
 283         }
 284
 285         scllo(adap);
 286         sda = getsda(adap);
 287         scl = (adap->getscl == NULL) ? 0 : getscl(adap);
 288         if (scl) {
 289                 printk(KERN_WARNING "%s: SCL stuck high!\n", name);
 290                 goto bailout;
 291         }
 292         if (!sda) {
 293                 printk(KERN_WARNING "%s: SDA unexpected low "
 294                        "while pulling SCL low!\n", name);
 295                 goto bailout;
 296         }
 297
 298         sclhi(adap);
 299         sda = getsda(adap);
 300         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
 301         if (!scl) {
 302                 printk(KERN_WARNING "%s: SCL stuck low!\n", name);
 303                 goto bailout;
 304         }
 305         if (!sda) {
 306                 printk(KERN_WARNING "%s: SDA unexpected low "
 307                        "while pulling SCL high!\n", name);
 308                 goto bailout;
 309         }
 310
 311         if (adap->post_xfer)
 312                 adap->post_xfer(i2c_adap);
 313
 314         pr_info("%s: Test OK\n", name);
 315         return 0;
 316 bailout:
 317         sdahi(adap);
 318         sclhi(adap);
 319
 320         if (adap->post_xfer)
 321                 adap->post_xfer(i2c_adap);
 322
 323         return -ENODEV;
 324 }
 325
 326 /* ----- Utility functions
 327  */
 328
 329 /* try_address tries to contact a chip for a number of
 330  * times before it gives up.
 331  * return values:
 332  * 1 chip answered
 333  * 0 chip did not answer
 334  * -x transmission error
 335  */
 336 static int try_address(struct i2c_adapter *i2c_adap,
 337                        unsigned char addr, int retries)
 338 {
 339         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 340         int i, ret = 0;
 341
 342         for (i = 0; i <= retries; i++) {
 343                 ret = i2c_outb(i2c_adap, addr);
 344                 if (ret == 1 || i == retries)
 345                         break;
 346                 bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
 347                 i2c_stop(adap);
 348                 udelay(adap->udelay);
 349                 yield();
 350                 bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
 351                 i2c_start(adap);
 352         }
 353         if (i && ret)
 354                 bit_dbg(1, &i2c_adap->dev, "Used %d tries to %s client at "
 355                         "0x%02x: %s\n", i + 1,
 356                         addr & 1 ? "read from" : "write to", addr >> 1,
 357                         ret == 1 ? "success" : "failed, timeout?");
 358         return ret;
 359 }
 360
 361 static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 362 {
 363         const unsigned char *temp = msg->buf;
 364         int count = msg->len;
 365         unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
 366         int retval;
 367         int wrcount = 0;
 368
 369         while (count > 0) {
 370                 retval = i2c_outb(i2c_adap, *temp);
 371
 372                 /* OK/ACK; or ignored NAK */
 373                 if ((retval > 0) || (nak_ok && (retval == 0))) {
 374                         count--;
 375                         temp++;
 376                         wrcount++;
 377
 378                 /* A slave NAKing the master means the slave didn't like
 379                  * something about the data it saw.  For example, maybe
 380                  * the SMBus PEC was wrong.
 381                  */
 382                 } else if (retval == 0) {
 383                         dev_err(&i2c_adap->dev, "sendbytes: NAK bailout.\n");
 384                         return -EIO;
 385
 386                 /* Timeout; or (someday) lost arbitration
 387                  *
 388                  * FIXME Lost ARB implies retrying the transaction from
 389                  * the first message, after the "winning" master issues
 390                  * its STOP.  As a rule, upper layer code has no reason
 391                  * to know or care about this ... it is *NOT* an error.
 392                  */
 393                 } else {
 394                         dev_err(&i2c_adap->dev, "sendbytes: error %d\n",
 395                                         retval);
 396                         return retval;
 397                 }
 398         }
 399         return wrcount;
 400 }
 401
 402 static int acknak(struct i2c_adapter *i2c_adap, int is_ack)
 403 {
 404         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 405
 406         /* assert: sda is high */
 407         if (is_ack)             /* send ack */
 408                 setsda(adap, 0);
 409         udelay((adap->udelay + 1) / 2);
 410         if (sclhi(adap) < 0) {  /* timeout */
 411                 dev_err(&i2c_adap->dev, "readbytes: ack/nak timeout\n");
 412                 return -ETIMEDOUT;
 413         }
 414         scllo(adap);
 415         return 0;
 416 }
 417
 418 static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 419 {
 420         int inval;
 421         int rdcount = 0;        /* counts bytes read */
 422         unsigned char *temp = msg->buf;
 423         int count = msg->len;
 424         const unsigned flags = msg->flags;
 425
 426         while (count > 0) {
 427                 inval = i2c_inb(i2c_adap);
 428                 if (inval >= 0) {
 429                         *temp = inval;
 430                         rdcount++;
 431                 } else {   /* read timed out */
 432                         break;
 433                 }
 434
 435                 temp++;
 436                 count--;
 437
 438                 /* Some SMBus transactions require that we receive the
 439                    transaction length as the first read byte. */
 440                 if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) {
 441                         if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) {
 442                                 if (!(flags & I2C_M_NO_RD_ACK))
 443                                         acknak(i2c_adap, 0);
 444                                 dev_err(&i2c_adap->dev, "readbytes: invalid "
 445                                         "block length (%d)\n", inval);
 446                                 return -EPROTO;
 447                         }
 448                         /* The original count value accounts for the extra
 449                            bytes, that is, either 1 for a regular transaction,
 450                            or 2 for a PEC transaction. */
 451                         count += inval;
 452                         msg->len += inval;
 453                 }
 454
 455                 bit_dbg(2, &i2c_adap->dev, "readbytes: 0x%02x %s\n",
 456                         inval,
 457                         (flags & I2C_M_NO_RD_ACK)
 458                                 ? "(no ack/nak)"
 459                                 : (count ? "A" : "NA"));
 460
 461                 if (!(flags & I2C_M_NO_RD_ACK)) {
 462                         inval = acknak(i2c_adap, count);
 463                         if (inval < 0)
 464                                 return inval;
 465                 }
 466         }
 467         return rdcount;
 468 }
 469
 470 /* doAddress initiates the transfer by generating the start condition (in
 471  * try_address) and transmits the address in the necessary format to handle
 472  * reads, writes as well as 10bit-addresses.
 473  * returns:
 474  *  0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set
 475  * -x an error occurred (like: -ENXIO if the device did not answer, or
 476  *      -ETIMEDOUT, for example if the lines are stuck...)
 477  */
 478 static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 479 {
 480         unsigned short flags = msg->flags;
 481         unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
 482         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 483
 484         unsigned char addr;
 485         int ret, retries;
 486
 487         retries = nak_ok ? 0 : i2c_adap->retries;
 488
 489         if (flags & I2C_M_TEN) {
 490                 /* a ten bit address */
 491                 addr = 0xf0 | ((msg->addr >> 7) & 0x06);
 492                 bit_dbg(2, &i2c_adap->dev, "addr0: %d\n", addr);
 493                 /* try extended address code...*/
 494                 ret = try_address(i2c_adap, addr, retries);
 495                 if ((ret != 1) && !nak_ok)  {
 496                         dev_err(&i2c_adap->dev,
 497                                 "died at extended address code\n");
 498                         return -ENXIO;
 499                 }
 500                 /* the remaining 8 bit address */
 501                 ret = i2c_outb(i2c_adap, msg->addr & 0xff);
 502                 if ((ret != 1) && !nak_ok) {
 503                         /* the chip did not ack / xmission error occurred */
 504                         dev_err(&i2c_adap->dev, "died at 2nd address code\n");
 505                         return -ENXIO;
 506                 }
 507                 if (flags & I2C_M_RD) {
 508                         bit_dbg(3, &i2c_adap->dev, "emitting repeated "
 509                                 "start condition\n");
 510                         i2c_repstart(adap);
 511                         /* okay, now switch into reading mode */
 512                         addr |= 0x01;
 513                         ret = try_address(i2c_adap, addr, retries);
 514                         if ((ret != 1) && !nak_ok) {
 515                                 dev_err(&i2c_adap->dev,
 516                                         "died at repeated address code\n");
 517                                 return -EIO;
 518                         }
 519                 }
 520         } else {                /* normal 7bit address  */
 521                 addr = msg->addr << 1;
 522                 if (flags & I2C_M_RD)
 523                         addr |= 1;
 524                 if (flags & I2C_M_REV_DIR_ADDR)
 525                         addr ^= 1;
 526                 ret = try_address(i2c_adap, addr, retries);
 527                 if ((ret != 1) && !nak_ok)
 528                         return -ENXIO;
 529         }
 530
 531         return 0;
 532 }
 533
 534 static int bit_xfer(struct i2c_adapter *i2c_adap,
 535                     struct i2c_msg msgs[], int num)
 536 {
 537         struct i2c_msg *pmsg;
 538         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 539         int i, ret;
 540         unsigned short nak_ok;
 541
 542         if (adap->pre_xfer) {
 543                 ret = adap->pre_xfer(i2c_adap);
 544                 if (ret < 0)
 545                         return ret;
 546         }
 547
 548         bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
 549         i2c_start(adap);
 550         for (i = 0; i < num; i++) {
 551                 pmsg = &msgs[i];
 552                 nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
 553                 if (!(pmsg->flags & I2C_M_NOSTART)) {
 554                         if (i) {
 555                                 bit_dbg(3, &i2c_adap->dev, "emitting "
 556                                         "repeated start condition\n");
 557                                 i2c_repstart(adap);
 558                         }
 559                         ret = bit_doAddress(i2c_adap, pmsg);
 560                         if ((ret != 0) && !nak_ok) {
 561                                 bit_dbg(1, &i2c_adap->dev, "NAK from "
 562                                         "device addr 0x%02x msg #%d\n",
 563                                         msgs[i].addr, i);
 564                                 goto bailout;
 565                         }
 566                 }
 567                 if (pmsg->flags & I2C_M_RD) {
 568                         /* read bytes into buffer*/
 569                         ret = readbytes(i2c_adap, pmsg);
 570                         if (ret >= 1)
 571                                 bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n",
 572                                         ret, ret == 1 ? "" : "s");
 573                         if (ret < pmsg->len) {
 574                                 if (ret >= 0)
 575                                         ret = -EIO;
 576                                 goto bailout;
 577                         }
 578                 } else {
 579                         /* write bytes from buffer */
 580                         ret = sendbytes(i2c_adap, pmsg);
 581                         if (ret >= 1)
 582                                 bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n",
 583                                         ret, ret == 1 ? "" : "s");
 584                         if (ret < pmsg->len) {
 585                                 if (ret >= 0)
 586                                         ret = -EIO;
 587                                 goto bailout;
 588                         }
 589                 }
 590         }
 591         ret = i;
 592
 593 bailout:
 594         bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
 595         i2c_stop(adap);
 596
 597         if (adap->post_xfer)
 598                 adap->post_xfer(i2c_adap);
 599         return ret;
 600 }
 601
 602 static u32 bit_func(struct i2c_adapter *adap)
 603 {
 604         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 605                I2C_FUNC_SMBUS_READ_BLOCK_DATA |
 606                I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
 607                I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
 608 }
 609
 610
 611 /* -----exported algorithm data: -------------------------------------  */
 612
 613 static const struct i2c_algorithm i2c_bit_algo = {
 614         .master_xfer    = bit_xfer,
 615         .functionality  = bit_func,
 616 };
 617
 618 /*
 619  * registering functions to load algorithms at runtime
 620  */
 621 static int __i2c_bit_add_bus(struct i2c_adapter *adap,
 622                              int (*add_adapter)(struct i2c_adapter *))
 623 {
 624         struct i2c_algo_bit_data *bit_adap = adap->algo_data;
 625         int ret;
 626
 627         if (bit_test) {
 628                 ret = test_bus(adap);
 629                 if (bit_test >= 2 && ret < 0)
 630                         return -ENODEV;
 631         }
 632
 633         /* register new adapter to i2c module... */
 634         adap->algo = &i2c_bit_algo;
 635         adap->retries = 3;
 636
 637         ret = add_adapter(adap);
 638         if (ret < 0)
 639                 return ret;
 640
 641         /* Complain if SCL can't be read */
 642         if (bit_adap->getscl == NULL) {
 643                 dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n");
 644                 dev_warn(&adap->dev, "Bus may be unreliable\n");
 645         }
 646         return 0;
 647 }
 648
 649 int i2c_bit_add_bus(struct i2c_adapter *adap)
 650 {
 651         return __i2c_bit_add_bus(adap, i2c_add_adapter);
 652 }
 653 EXPORT_SYMBOL(i2c_bit_add_bus);
 654
 655 int i2c_bit_add_numbered_bus(struct i2c_adapter *adap)
 656 {
 657         return __i2c_bit_add_bus(adap, i2c_add_numbered_adapter);
 658 }
 659 EXPORT_SYMBOL(i2c_bit_add_numbered_bus);
 660
 661 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 662 MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
 663 MODULE_LICENSE("GPL");