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

   1 /* ------------------------------------------------------------------------- */
   2 /* i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters                 */
   3 /* ------------------------------------------------------------------------- */
   4 /*   Copyright (C) 1995-1997 Simon G. Vogl
   5                    1998-2000 Hans Berglund
   6
   7     This program is free software; you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation; either version 2 of the License, or
  10     (at your option) any later version.
  11
  12     This program is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16
  17     You should have received a copy of the GNU General Public License
  18     along with this program; if not, write to the Free Software
  19     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.                */
  20 /* ------------------------------------------------------------------------- */
  21
  22 /* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
  23    Frodo Looijaard <frodol@dds.nl> ,and also from Martin Bailey
  24    <mbailey@littlefeet-inc.com> */
  25
  26 /* Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
  27    messages, proper stop/repstart signaling during receive,
  28    added detect code */
  29
  30 #include <linux/kernel.h>
  31 #include <linux/module.h>
  32 #include <linux/delay.h>
  33 #include <linux/slab.h>
  34 #include <linux/init.h>
  35 #include <linux/errno.h>
  36 #include <linux/i2c.h>
  37 #include <linux/i2c-algo-pcf.h>
  38 #include "i2c-algo-pcf.h"
  39
  40
  41 #define DEB2(x) if (i2c_debug>=2) x
  42 #define DEB3(x) if (i2c_debug>=3) x /* print several statistical values*/
  43 #define DEBPROTO(x) if (i2c_debug>=9) x;
  44         /* debug the protocol by showing transferred bits */
  45 #define DEF_TIMEOUT 16
  46
  47 /* module parameters:
  48  */
  49 static int i2c_debug;
  50
  51 /* --- setting states on the bus with the right timing: --------------- */
  52
  53 #define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
  54 #define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
  55 #define get_own(adap) adap->getown(adap->data)
  56 #define get_clock(adap) adap->getclock(adap->data)
  57 #define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
  58 #define i2c_inb(adap) adap->getpcf(adap->data, 0)
  59
  60 /* --- other auxiliary functions -------------------------------------- */
  61
  62 static void i2c_start(struct i2c_algo_pcf_data *adap)
  63 {
  64         DEBPROTO(printk("S "));
  65         set_pcf(adap, 1, I2C_PCF_START);
  66 }
  67
  68 static void i2c_repstart(struct i2c_algo_pcf_data *adap)
  69 {
  70         DEBPROTO(printk(" Sr "));
  71         set_pcf(adap, 1, I2C_PCF_REPSTART);
  72 }
  73
  74
  75 static void i2c_stop(struct i2c_algo_pcf_data *adap)
  76 {
  77         DEBPROTO(printk("P\n"));
  78         set_pcf(adap, 1, I2C_PCF_STOP);
  79 }
  80
  81 static int wait_for_bb(struct i2c_algo_pcf_data *adap) {
  82
  83         int timeout = DEF_TIMEOUT;
  84         int status;
  85
  86         status = get_pcf(adap, 1);
  87 #ifndef STUB_I2C
  88         while (timeout-- && !(status & I2C_PCF_BB)) {
  89                 udelay(100); /* wait for 100 us */
  90                 status = get_pcf(adap, 1);
  91         }
  92 #endif
  93         if (timeout <= 0) {
  94                 printk(KERN_ERR "Timeout waiting for Bus Busy\n");
  95         }
  96
  97         return (timeout<=0);
  98 }
  99
 100
 101 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status) {
 102
 103         int timeout = DEF_TIMEOUT;
 104
 105         *status = get_pcf(adap, 1);
 106 #ifndef STUB_I2C
 107         while (timeout-- && (*status & I2C_PCF_PIN)) {
 108                 adap->waitforpin();
 109                 *status = get_pcf(adap, 1);
 110         }
 111         if (*status & I2C_PCF_LAB) {
 112                 DEB2(printk(KERN_INFO
 113                         "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
 114                          *status));
 115                 /* Cleanup from LAB-- reset and enable ESO.
 116                  * This resets the PCF8584; since we've lost the bus, no
 117                  * further attempts should be made by callers to clean up
 118                  * (no i2c_stop() etc.)
 119                  */
 120                 set_pcf(adap, 1, I2C_PCF_PIN);
 121                 set_pcf(adap, 1, I2C_PCF_ESO);
 122                 /* TODO: we should pause for a time period sufficient for any
 123                  * running I2C transaction to complete-- the arbitration
 124                  * logic won't work properly until the next START is seen.
 125                  */
 126                 DEB2(printk(KERN_INFO
 127                         "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
 128                         get_pcf(adap,1)));
 129                 return(-EINTR);
 130         }
 131 #endif
 132         if (timeout <= 0)
 133                 return(-1);
 134         else
 135                 return(0);
 136 }
 137
 138 /*
 139  * This should perform the 'PCF8584 initialization sequence' as described
 140  * in the Philips IC12 data book (1995, Aug 29).
 141  * There should be a 30 clock cycle wait after reset, I assume this
 142  * has been fulfilled.
 143  * There should be a delay at the end equal to the longest I2C message
 144  * to synchronize the BB-bit (in multimaster systems). How long is
 145  * this? I assume 1 second is always long enough.
 146  *
 147  * vdovikin: added detect code for PCF8584
 148  */
 149 static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
 150 {
 151         unsigned char temp;
 152
 153         DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n", get_pcf(adap, 1)));
 154
 155         /* S1=0x80: S0 selected, serial interface off */
 156         set_pcf(adap, 1, I2C_PCF_PIN);
 157         /* check to see S1 now used as R/W ctrl -
 158            PCF8584 does that when ESO is zero */
 159         if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
 160                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
 161                 return -ENXIO; /* definetly not PCF8584 */
 162         }
 163
 164         /* load own address in S0, effective address is (own << 1)      */
 165         i2c_outb(adap, get_own(adap));
 166         /* check it's really written */
 167         if ((temp = i2c_inb(adap)) != get_own(adap)) {
 168                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
 169                 return -ENXIO;
 170         }
 171
 172         /* S1=0xA0, next byte in S2                                     */
 173         set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
 174         /* check to see S2 now selected */
 175         if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
 176                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
 177                 return -ENXIO;
 178         }
 179
 180         /* load clock register S2                                       */
 181         i2c_outb(adap, get_clock(adap));
 182         /* check it's really written, the only 5 lowest bits does matter */
 183         if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
 184                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
 185                 return -ENXIO;
 186         }
 187
 188         /* Enable serial interface, idle, S0 selected                   */
 189         set_pcf(adap, 1, I2C_PCF_IDLE);
 190
 191         /* check to see PCF is really idled and we can access status register */
 192         if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
 193                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
 194                 return -ENXIO;
 195         }
 196
 197         printk(KERN_DEBUG "i2c-algo-pcf.o: deteted and initialized PCF8584.\n");
 198
 199         return 0;
 200 }
 201
 202
 203 /* ----- Utility functions
 204  */
 205
 206 static inline int try_address(struct i2c_algo_pcf_data *adap,
 207                        unsigned char addr, int retries)
 208 {
 209         int i, status, ret = -1;
 210         int wfp;
 211         for (i=0;i<retries;i++) {
 212                 i2c_outb(adap, addr);
 213                 i2c_start(adap);
 214                 status = get_pcf(adap, 1);
 215                 if ((wfp = wait_for_pin(adap, &status)) >= 0) {
 216                         if ((status & I2C_PCF_LRB) == 0) {
 217                                 i2c_stop(adap);
 218                                 break;  /* success! */
 219                         }
 220                 }
 221                 if (wfp == -EINTR) {
 222                         /* arbitration lost */
 223                         udelay(adap->udelay);
 224                         return -EINTR;
 225                 }
 226                 i2c_stop(adap);
 227                 udelay(adap->udelay);
 228         }
 229         DEB2(if (i) printk(KERN_DEBUG "i2c-algo-pcf.o: needed %d retries for %d\n",i,
 230                            addr));
 231         return ret;
 232 }
 233
 234
 235 static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
 236                          int count, int last)
 237 {
 238         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 239         int wrcount, status, timeout;
 240
 241         for (wrcount=0; wrcount<count; ++wrcount) {
 242                 DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
 243                                 buf[wrcount]&0xff));
 244                 i2c_outb(adap, buf[wrcount]);
 245                 timeout = wait_for_pin(adap, &status);
 246                 if (timeout) {
 247                         if (timeout == -EINTR) {
 248                                 /* arbitration lost */
 249                                 return -EINTR;
 250                         }
 251                         i2c_stop(adap);
 252                         dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
 253                         return -EREMOTEIO; /* got a better one ?? */
 254                 }
 255 #ifndef STUB_I2C
 256                 if (status & I2C_PCF_LRB) {
 257                         i2c_stop(adap);
 258                         dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
 259                         return -EREMOTEIO; /* got a better one ?? */
 260                 }
 261 #endif
 262         }
 263         if (last) {
 264                 i2c_stop(adap);
 265         }
 266         else {
 267                 i2c_repstart(adap);
 268         }
 269
 270         return (wrcount);
 271 }
 272
 273
 274 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
 275                          int count, int last)
 276 {
 277         int i, status;
 278         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 279         int wfp;
 280
 281         /* increment number of bytes to read by one -- read dummy byte */
 282         for (i = 0; i <= count; i++) {
 283
 284                 if ((wfp = wait_for_pin(adap, &status))) {
 285                         if (wfp == -EINTR) {
 286                                 /* arbitration lost */
 287                                 return -EINTR;
 288                         }
 289                         i2c_stop(adap);
 290                         dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
 291                         return (-1);
 292                 }
 293
 294 #ifndef STUB_I2C
 295                 if ((status & I2C_PCF_LRB) && (i != count)) {
 296                         i2c_stop(adap);
 297                         dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
 298                         return (-1);
 299                 }
 300 #endif
 301
 302                 if (i == count - 1) {
 303                         set_pcf(adap, 1, I2C_PCF_ESO);
 304                 } else
 305                 if (i == count) {
 306                         if (last) {
 307                                 i2c_stop(adap);
 308                         } else {
 309                                 i2c_repstart(adap);
 310                         }
 311                 };
 312
 313                 if (i) {
 314                         buf[i - 1] = i2c_inb(adap);
 315                 } else {
 316                         i2c_inb(adap); /* dummy read */
 317                 }
 318         }
 319
 320         return (i - 1);
 321 }
 322
 323
 324 static inline int pcf_doAddress(struct i2c_algo_pcf_data *adap,
 325                                 struct i2c_msg *msg, int retries)
 326 {
 327         unsigned short flags = msg->flags;
 328         unsigned char addr;
 329         int ret;
 330         if ( (flags & I2C_M_TEN)  ) {
 331                 /* a ten bit address */
 332                 addr = 0xf0 | (( msg->addr >> 7) & 0x03);
 333                 DEB2(printk(KERN_DEBUG "addr0: %d\n",addr));
 334                 /* try extended address code...*/
 335                 ret = try_address(adap, addr, retries);
 336                 if (ret!=1) {
 337                         printk(KERN_ERR "died at extended address code.\n");
 338                         return -EREMOTEIO;
 339                 }
 340                 /* the remaining 8 bit address */
 341                 i2c_outb(adap,msg->addr & 0x7f);
 342 /* Status check comes here */
 343                 if (ret != 1) {
 344                         printk(KERN_ERR "died at 2nd address code.\n");
 345                         return -EREMOTEIO;
 346                 }
 347                 if ( flags & I2C_M_RD ) {
 348                         i2c_repstart(adap);
 349                         /* okay, now switch into reading mode */
 350                         addr |= 0x01;
 351                         ret = try_address(adap, addr, retries);
 352                         if (ret!=1) {
 353                                 printk(KERN_ERR "died at extended address code.\n");
 354                                 return -EREMOTEIO;
 355                         }
 356                 }
 357         } else {                /* normal 7bit address  */
 358                 addr = ( msg->addr << 1 );
 359                 if (flags & I2C_M_RD )
 360                         addr |= 1;
 361                 if (flags & I2C_M_REV_DIR_ADDR )
 362                         addr ^= 1;
 363                 i2c_outb(adap, addr);
 364         }
 365         return 0;
 366 }
 367
 368 static int pcf_xfer(struct i2c_adapter *i2c_adap,
 369                     struct i2c_msg *msgs,
 370                     int num)
 371 {
 372         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 373         struct i2c_msg *pmsg;
 374         int i;
 375         int ret=0, timeout, status;
 376
 377
 378         /* Check for bus busy */
 379         timeout = wait_for_bb(adap);
 380         if (timeout) {
 381                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
 382                             "Timeout waiting for BB in pcf_xfer\n");)
 383                 return -EIO;
 384         }
 385
 386         for (i = 0;ret >= 0 && i < num; i++) {
 387                 pmsg = &msgs[i];
 388
 389                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
 390                      pmsg->flags & I2C_M_RD ? "read" : "write",
 391                      pmsg->len, pmsg->addr, i + 1, num);)
 392
 393                 ret = pcf_doAddress(adap, pmsg, i2c_adap->retries);
 394
 395                 /* Send START */
 396                 if (i == 0) {
 397                         i2c_start(adap);
 398                 }
 399
 400                 /* Wait for PIN (pending interrupt NOT) */
 401                 timeout = wait_for_pin(adap, &status);
 402                 if (timeout) {
 403                         if (timeout == -EINTR) {
 404                                 /* arbitration lost */
 405                                 return (-EINTR);
 406                         }
 407                         i2c_stop(adap);
 408                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
 409                                     "for PIN(1) in pcf_xfer\n");)
 410                         return (-EREMOTEIO);
 411                 }
 412
 413 #ifndef STUB_I2C
 414                 /* Check LRB (last rcvd bit - slave ack) */
 415                 if (status & I2C_PCF_LRB) {
 416                         i2c_stop(adap);
 417                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
 418                         return (-EREMOTEIO);
 419                 }
 420 #endif
 421
 422                 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
 423                             i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
 424
 425                 /* Read */
 426                 if (pmsg->flags & I2C_M_RD) {
 427                         /* read bytes into buffer*/
 428                         ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
 429                                             (i + 1 == num));
 430
 431                         if (ret != pmsg->len) {
 432                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 433                                             "only read %d bytes.\n",ret));
 434                         } else {
 435                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
 436                         }
 437                 } else { /* Write */
 438                         ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
 439                                             (i + 1 == num));
 440
 441                         if (ret != pmsg->len) {
 442                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 443                                             "only wrote %d bytes.\n",ret));
 444                         } else {
 445                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
 446                         }
 447                 }
 448         }
 449
 450         return (i);
 451 }
 452
 453 static u32 pcf_func(struct i2c_adapter *adap)
 454 {
 455         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 456                I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
 457 }
 458
 459 /* -----exported algorithm data: -------------------------------------  */
 460
 461 static const struct i2c_algorithm pcf_algo = {
 462         .master_xfer    = pcf_xfer,
 463         .functionality  = pcf_func,
 464 };
 465
 466 /*
 467  * registering functions to load algorithms at runtime
 468  */
 469 int i2c_pcf_add_bus(struct i2c_adapter *adap)
 470 {
 471         struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
 472         int rval;
 473
 474         DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
 475
 476         /* register new adapter to i2c module... */
 477         adap->algo = &pcf_algo;
 478
 479         adap->timeout = 100;            /* default values, should       */
 480         adap->retries = 3;              /* be replaced by defines       */
 481
 482         if ((rval = pcf_init_8584(pcf_adap)))
 483                 return rval;
 484
 485         rval = i2c_add_adapter(adap);
 486
 487         return rval;
 488 }
 489 EXPORT_SYMBOL(i2c_pcf_add_bus);
 490
 491 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
 492 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
 493 MODULE_LICENSE("GPL");
 494
 495 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
 496 MODULE_PARM_DESC(i2c_debug,
 497         "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");