LXR linux/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 */
  49static 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
  62static void i2c_start(struct i2c_algo_pcf_data *adap) 
  63{
  64        DEBPROTO(printk("S "));
  65        set_pcf(adap, 1, I2C_PCF_START);
  66}
  67
  68static 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
  75static 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
  81static 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
 101static 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 */
 149static 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
 206static 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
 235static 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
 274static 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
 324static 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
 368static 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
 453static 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
 461static 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 */
 469int 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}
 489EXPORT_SYMBOL(i2c_pcf_add_bus);
 490
 491MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
 492MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
 493MODULE_LICENSE("GPL");
 494
 495module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
 496MODULE_PARM_DESC(i2c_debug,
 497        "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");
 498