release/src-rt-6.x.4708/linux/linux-2.6.36/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, bool, 0);
  51 MODULE_PARM_DESC(bit_test, "Test the lines of the bus to see if it is 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                 scllo(adap);
 178         }
 179         sdahi(adap);
 180         if (sclhi(adap) < 0) { /* timeout */
 181                 bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
 182                         "timeout at ack\n", (int)c);
 183                 return -ETIMEDOUT;
 184         }
 185
 186         /* read ack: SDA should be pulled down by slave, or it may
 187          * NAK (usually to report problems with the data we wrote).
 188          */
 189         ack = !getsda(adap);    /* ack: sda is pulled low -> success */
 190         bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n", (int)c,
 191                 ack ? "A" : "NA");
 192
 193         scllo(adap);
 194         return ack;
 195         /* assert: scl is low (sda undef) */
 196 }
 197
 198
 199 static int i2c_inb(struct i2c_adapter *i2c_adap)
 200 {
 201         /* read byte via i2c port, without start/stop sequence  */
 202         /* acknowledge is sent in i2c_read.                     */
 203         int i;
 204         unsigned char indata = 0;
 205         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 206
 207         /* assert: scl is low */
 208         sdahi(adap);
 209         for (i = 0; i < 8; i++) {
 210                 if (sclhi(adap) < 0) { /* timeout */
 211                         bit_dbg(1, &i2c_adap->dev, "i2c_inb: timeout at bit "
 212                                 "#%d\n", 7 - i);
 213                         return -ETIMEDOUT;
 214                 }
 215                 indata *= 2;
 216                 if (getsda(adap))
 217                         indata |= 0x01;
 218                 setscl(adap, 0);
 219                 udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
 220         }
 221         /* assert: scl is low */
 222         return indata;
 223 }
 224
 225 /*
 226  * Sanity check for the adapter hardware - check the reaction of
 227  * the bus lines only if it seems to be idle.
 228  */
 229 static int test_bus(struct i2c_algo_bit_data *adap, char *name)
 230 {
 231         int scl, sda;
 232
 233         if (adap->getscl == NULL)
 234                 pr_info("%s: Testing SDA only, SCL is not readable\n", name);
 235
 236         sda = getsda(adap);
 237         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
 238         if (!scl || !sda) {
 239                 printk(KERN_WARNING "%s: bus seems to be busy\n", name);
 240                 goto bailout;
 241         }
 242
 243         sdalo(adap);
 244         sda = getsda(adap);
 245         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
 246         if (sda) {
 247                 printk(KERN_WARNING "%s: SDA stuck high!\n", name);
 248                 goto bailout;
 249         }
 250         if (!scl) {
 251                 printk(KERN_WARNING "%s: SCL unexpected low "
 252                        "while pulling SDA low!\n", name);
 253                 goto bailout;
 254         }
 255
 256         sdahi(adap);
 257         sda = getsda(adap);
 258         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
 259         if (!sda) {
 260                 printk(KERN_WARNING "%s: SDA stuck low!\n", name);
 261                 goto bailout;
 262         }
 263         if (!scl) {
 264                 printk(KERN_WARNING "%s: SCL unexpected low "
 265                        "while pulling SDA high!\n", name);
 266                 goto bailout;
 267         }
 268
 269         scllo(adap);
 270         sda = getsda(adap);
 271         scl = (adap->getscl == NULL) ? 0 : getscl(adap);
 272         if (scl) {
 273                 printk(KERN_WARNING "%s: SCL stuck high!\n", name);
 274                 goto bailout;
 275         }
 276         if (!sda) {
 277                 printk(KERN_WARNING "%s: SDA unexpected low "
 278                        "while pulling SCL low!\n", name);
 279                 goto bailout;
 280         }
 281
 282         sclhi(adap);
 283         sda = getsda(adap);
 284         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
 285         if (!scl) {
 286                 printk(KERN_WARNING "%s: SCL stuck low!\n", name);
 287                 goto bailout;
 288         }
 289         if (!sda) {
 290                 printk(KERN_WARNING "%s: SDA unexpected low "
 291                        "while pulling SCL high!\n", name);
 292                 goto bailout;
 293         }
 294         pr_info("%s: Test OK\n", name);
 295         return 0;
 296 bailout:
 297         sdahi(adap);
 298         sclhi(adap);
 299         return -ENODEV;
 300 }
 301
 302 /* ----- Utility functions
 303  */
 304
 305 /* try_address tries to contact a chip for a number of
 306  * times before it gives up.
 307  * return values:
 308  * 1 chip answered
 309  * 0 chip did not answer
 310  * -x transmission error
 311  */
 312 static int try_address(struct i2c_adapter *i2c_adap,
 313                        unsigned char addr, int retries)
 314 {
 315         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 316         int i, ret = 0;
 317
 318         for (i = 0; i <= retries; i++) {
 319                 ret = i2c_outb(i2c_adap, addr);
 320                 if (ret == 1 || i == retries)
 321                         break;
 322                 bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
 323                 i2c_stop(adap);
 324                 udelay(adap->udelay);
 325                 yield();
 326                 bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
 327                 i2c_start(adap);
 328         }
 329         if (i && ret)
 330                 bit_dbg(1, &i2c_adap->dev, "Used %d tries to %s client at "
 331                         "0x%02x: %s\n", i + 1,
 332                         addr & 1 ? "read from" : "write to", addr >> 1,
 333                         ret == 1 ? "success" : "failed, timeout?");
 334         return ret;
 335 }
 336
 337 static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 338 {
 339         const unsigned char *temp = msg->buf;
 340         int count = msg->len;
 341         unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
 342         int retval;
 343         int wrcount = 0;
 344
 345         while (count > 0) {
 346                 retval = i2c_outb(i2c_adap, *temp);
 347
 348                 /* OK/ACK; or ignored NAK */
 349                 if ((retval > 0) || (nak_ok && (retval == 0))) {
 350                         count--;
 351                         temp++;
 352                         wrcount++;
 353
 354                 /* A slave NAKing the master means the slave didn't like
 355                  * something about the data it saw.  For example, maybe
 356                  * the SMBus PEC was wrong.
 357                  */
 358                 } else if (retval == 0) {
 359                         dev_err(&i2c_adap->dev, "sendbytes: NAK bailout.\n");
 360                         return -EIO;
 361
 362                 } else {
 363                         dev_err(&i2c_adap->dev, "sendbytes: error %d\n",
 364                                         retval);
 365                         return retval;
 366                 }
 367         }
 368         return wrcount;
 369 }
 370
 371 static int acknak(struct i2c_adapter *i2c_adap, int is_ack)
 372 {
 373         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 374
 375         /* assert: sda is high */
 376         if (is_ack)             /* send ack */
 377                 setsda(adap, 0);
 378         udelay((adap->udelay + 1) / 2);
 379         if (sclhi(adap) < 0) {  /* timeout */
 380                 dev_err(&i2c_adap->dev, "readbytes: ack/nak timeout\n");
 381                 return -ETIMEDOUT;
 382         }
 383         scllo(adap);
 384         return 0;
 385 }
 386
 387 static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 388 {
 389         int inval;
 390         int rdcount = 0;        /* counts bytes read */
 391         unsigned char *temp = msg->buf;
 392         int count = msg->len;
 393         const unsigned flags = msg->flags;
 394
 395         while (count > 0) {
 396                 inval = i2c_inb(i2c_adap);
 397                 if (inval >= 0) {
 398                         *temp = inval;
 399                         rdcount++;
 400                 } else {   /* read timed out */
 401                         break;
 402                 }
 403
 404                 temp++;
 405                 count--;
 406
 407                 /* Some SMBus transactions require that we receive the
 408                    transaction length as the first read byte. */
 409                 if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) {
 410                         if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) {
 411                                 if (!(flags & I2C_M_NO_RD_ACK))
 412                                         acknak(i2c_adap, 0);
 413                                 dev_err(&i2c_adap->dev, "readbytes: invalid "
 414                                         "block length (%d)\n", inval);
 415                                 return -EREMOTEIO;
 416                         }
 417                         /* The original count value accounts for the extra
 418                            bytes, that is, either 1 for a regular transaction,
 419                            or 2 for a PEC transaction. */
 420                         count += inval;
 421                         msg->len += inval;
 422                 }
 423
 424                 bit_dbg(2, &i2c_adap->dev, "readbytes: 0x%02x %s\n",
 425                         inval,
 426                         (flags & I2C_M_NO_RD_ACK)
 427                                 ? "(no ack/nak)"
 428                                 : (count ? "A" : "NA"));
 429
 430                 if (!(flags & I2C_M_NO_RD_ACK)) {
 431                         inval = acknak(i2c_adap, count);
 432                         if (inval < 0)
 433                                 return inval;
 434                 }
 435         }
 436         return rdcount;
 437 }
 438
 439 /* doAddress initiates the transfer by generating the start condition (in
 440  * try_address) and transmits the address in the necessary format to handle
 441  * reads, writes as well as 10bit-addresses.
 442  * returns:
 443  *  0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set
 444  * -x an error occurred (like: -EREMOTEIO if the device did not answer, or
 445  *      -ETIMEDOUT, for example if the lines are stuck...)
 446  */
 447 static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 448 {
 449         unsigned short flags = msg->flags;
 450         unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
 451         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 452
 453         unsigned char addr;
 454         int ret, retries;
 455
 456         retries = nak_ok ? 0 : i2c_adap->retries;
 457
 458         if (flags & I2C_M_TEN) {
 459                 /* a ten bit address */
 460                 addr = 0xf0 | ((msg->addr >> 7) & 0x03);
 461                 bit_dbg(2, &i2c_adap->dev, "addr0: %d\n", addr);
 462                 /* try extended address code...*/
 463                 ret = try_address(i2c_adap, addr, retries);
 464                 if ((ret != 1) && !nak_ok)  {
 465                         dev_err(&i2c_adap->dev,
 466                                 "died at extended address code\n");
 467                         return -EREMOTEIO;
 468                 }
 469                 /* the remaining 8 bit address */
 470                 ret = i2c_outb(i2c_adap, msg->addr & 0x7f);
 471                 if ((ret != 1) && !nak_ok) {
 472                         /* the chip did not ack / xmission error occurred */
 473                         dev_err(&i2c_adap->dev, "died at 2nd address code\n");
 474                         return -EREMOTEIO;
 475                 }
 476                 if (flags & I2C_M_RD) {
 477                         bit_dbg(3, &i2c_adap->dev, "emitting repeated "
 478                                 "start condition\n");
 479                         i2c_repstart(adap);
 480                         /* okay, now switch into reading mode */
 481                         addr |= 0x01;
 482                         ret = try_address(i2c_adap, addr, retries);
 483                         if ((ret != 1) && !nak_ok) {
 484                                 dev_err(&i2c_adap->dev,
 485                                         "died at repeated address code\n");
 486                                 return -EREMOTEIO;
 487                         }
 488                 }
 489         } else {                /* normal 7bit address  */
 490                 addr = msg->addr << 1;
 491                 if (flags & I2C_M_RD)
 492                         addr |= 1;
 493                 if (flags & I2C_M_REV_DIR_ADDR)
 494                         addr ^= 1;
 495                 ret = try_address(i2c_adap, addr, retries);
 496                 if ((ret != 1) && !nak_ok)
 497                         return -ENXIO;
 498         }
 499
 500         return 0;
 501 }
 502
 503 static int bit_xfer(struct i2c_adapter *i2c_adap,
 504                     struct i2c_msg msgs[], int num)
 505 {
 506         struct i2c_msg *pmsg;
 507         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 508         int i, ret;
 509         unsigned short nak_ok;
 510
 511         if (adap->pre_xfer) {
 512                 ret = adap->pre_xfer(i2c_adap);
 513                 if (ret < 0)
 514                         return ret;
 515         }
 516
 517         bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
 518         i2c_start(adap);
 519         for (i = 0; i < num; i++) {
 520                 pmsg = &msgs[i];
 521                 nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
 522                 if (!(pmsg->flags & I2C_M_NOSTART)) {
 523                         if (i) {
 524                                 bit_dbg(3, &i2c_adap->dev, "emitting "
 525                                         "repeated start condition\n");
 526                                 i2c_repstart(adap);
 527                         }
 528                         ret = bit_doAddress(i2c_adap, pmsg);
 529                         if ((ret != 0) && !nak_ok) {
 530                                 bit_dbg(1, &i2c_adap->dev, "NAK from "
 531                                         "device addr 0x%02x msg #%d\n",
 532                                         msgs[i].addr, i);
 533                                 goto bailout;
 534                         }
 535                 }
 536                 if (pmsg->flags & I2C_M_RD) {
 537                         /* read bytes into buffer*/
 538                         ret = readbytes(i2c_adap, pmsg);
 539                         if (ret >= 1)
 540                                 bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n",
 541                                         ret, ret == 1 ? "" : "s");
 542                         if (ret < pmsg->len) {
 543                                 if (ret >= 0)
 544                                         ret = -EREMOTEIO;
 545                                 goto bailout;
 546                         }
 547                 } else {
 548                         /* write bytes from buffer */
 549                         ret = sendbytes(i2c_adap, pmsg);
 550                         if (ret >= 1)
 551                                 bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n",
 552                                         ret, ret == 1 ? "" : "s");
 553                         if (ret < pmsg->len) {
 554                                 if (ret >= 0)
 555                                         ret = -EREMOTEIO;
 556                                 goto bailout;
 557                         }
 558                 }
 559         }
 560         ret = i;
 561
 562 bailout:
 563         bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
 564         i2c_stop(adap);
 565
 566         if (adap->post_xfer)
 567                 adap->post_xfer(i2c_adap);
 568         return ret;
 569 }
 570
 571 static u32 bit_func(struct i2c_adapter *adap)
 572 {
 573         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 574                I2C_FUNC_SMBUS_READ_BLOCK_DATA |
 575                I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
 576                I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
 577 }
 578
 579
 580 /* -----exported algorithm data: -------------------------------------  */
 581
 582 static const struct i2c_algorithm i2c_bit_algo = {
 583         .master_xfer    = bit_xfer,
 584         .functionality  = bit_func,
 585 };
 586
 587 /*
 588  * registering functions to load algorithms at runtime
 589  */
 590 static int i2c_bit_prepare_bus(struct i2c_adapter *adap)
 591 {
 592         struct i2c_algo_bit_data *bit_adap = adap->algo_data;
 593
 594         if (bit_test) {
 595                 int ret = test_bus(bit_adap, adap->name);
 596                 if (ret < 0)
 597                         return -ENODEV;
 598         }
 599
 600         /* register new adapter to i2c module... */
 601         adap->algo = &i2c_bit_algo;
 602         adap->retries = 3;
 603
 604         return 0;
 605 }
 606
 607 int i2c_bit_add_bus(struct i2c_adapter *adap)
 608 {
 609         int err;
 610
 611         err = i2c_bit_prepare_bus(adap);
 612         if (err)
 613                 return err;
 614
 615         return i2c_add_adapter(adap);
 616 }
 617 EXPORT_SYMBOL(i2c_bit_add_bus);
 618
 619 int i2c_bit_add_numbered_bus(struct i2c_adapter *adap)
 620 {
 621         int err;
 622
 623         err = i2c_bit_prepare_bus(adap);
 624         if (err)
 625                 return err;
 626
 627         return i2c_add_numbered_adapter(adap);
 628 }
 629 EXPORT_SYMBOL(i2c_bit_add_numbered_bus);
 630
 631 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 632 MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
 633 MODULE_LICENSE("GPL");