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 void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
  82 {
  83         DEB2(printk(KERN_INFO
  84                 "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
  85                  *status));
  86
  87         /* Cleanup from LAB -- reset and enable ESO.
  88          * This resets the PCF8584; since we've lost the bus, no
  89          * further attempts should be made by callers to clean up
  90          * (no i2c_stop() etc.)
  91          */
  92         set_pcf(adap, 1, I2C_PCF_PIN);
  93         set_pcf(adap, 1, I2C_PCF_ESO);
  94
  95         /* We pause for a time period sufficient for any running
  96          * I2C transaction to complete -- the arbitration logic won't
  97          * work properly until the next START is seen.
  98          * It is assumed the bus driver or client has set a proper value.
  99          *
 100          * REVISIT: should probably use msleep instead of mdelay if we
 101          * know we can sleep.
 102          */
 103         if (adap->lab_mdelay)
 104                 mdelay(adap->lab_mdelay);
 105
 106         DEB2(printk(KERN_INFO
 107                 "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
 108                 get_pcf(adap, 1)));
 109 }
 110
 111 static int wait_for_bb(struct i2c_algo_pcf_data *adap) {
 112
 113         int timeout = DEF_TIMEOUT;
 114         int status;
 115
 116         status = get_pcf(adap, 1);
 117 #ifndef STUB_I2C
 118         while (timeout-- && !(status & I2C_PCF_BB)) {
 119                 udelay(100); /* wait for 100 us */
 120                 status = get_pcf(adap, 1);
 121         }
 122 #endif
 123         if (timeout <= 0) {
 124                 printk(KERN_ERR "Timeout waiting for Bus Busy\n");
 125         }
 126
 127         return (timeout<=0);
 128 }
 129
 130
 131 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status) {
 132
 133         int timeout = DEF_TIMEOUT;
 134
 135         *status = get_pcf(adap, 1);
 136 #ifndef STUB_I2C
 137         while (timeout-- && (*status & I2C_PCF_PIN)) {
 138                 adap->waitforpin();
 139                 *status = get_pcf(adap, 1);
 140         }
 141         if (*status & I2C_PCF_LAB) {
 142                 handle_lab(adap, status);
 143                 return(-EINTR);
 144         }
 145 #endif
 146         if (timeout <= 0)
 147                 return(-1);
 148         else
 149                 return(0);
 150 }
 151
 152 /*
 153  * This should perform the 'PCF8584 initialization sequence' as described
 154  * in the Philips IC12 data book (1995, Aug 29).
 155  * There should be a 30 clock cycle wait after reset, I assume this
 156  * has been fulfilled.
 157  * There should be a delay at the end equal to the longest I2C message
 158  * to synchronize the BB-bit (in multimaster systems). How long is
 159  * this? I assume 1 second is always long enough.
 160  *
 161  * vdovikin: added detect code for PCF8584
 162  */
 163 static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
 164 {
 165         unsigned char temp;
 166
 167         DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n", get_pcf(adap, 1)));
 168
 169         /* S1=0x80: S0 selected, serial interface off */
 170         set_pcf(adap, 1, I2C_PCF_PIN);
 171         /* check to see S1 now used as R/W ctrl -
 172            PCF8584 does that when ESO is zero */
 173         if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
 174                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
 175                 return -ENXIO; /* definetly not PCF8584 */
 176         }
 177
 178         /* load own address in S0, effective address is (own << 1)      */
 179         i2c_outb(adap, get_own(adap));
 180         /* check it's really written */
 181         if ((temp = i2c_inb(adap)) != get_own(adap)) {
 182                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
 183                 return -ENXIO;
 184         }
 185
 186         /* S1=0xA0, next byte in S2                                     */
 187         set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
 188         /* check to see S2 now selected */
 189         if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
 190                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
 191                 return -ENXIO;
 192         }
 193
 194         /* load clock register S2                                       */
 195         i2c_outb(adap, get_clock(adap));
 196         /* check it's really written, the only 5 lowest bits does matter */
 197         if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
 198                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
 199                 return -ENXIO;
 200         }
 201
 202         /* Enable serial interface, idle, S0 selected                   */
 203         set_pcf(adap, 1, I2C_PCF_IDLE);
 204
 205         /* check to see PCF is really idled and we can access status register */
 206         if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
 207                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
 208                 return -ENXIO;
 209         }
 210
 211         printk(KERN_DEBUG "i2c-algo-pcf.o: deteted and initialized PCF8584.\n");
 212
 213         return 0;
 214 }
 215
 216
 217 /* ----- Utility functions
 218  */
 219
 220 static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
 221                          int count, int last)
 222 {
 223         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 224         int wrcount, status, timeout;
 225
 226         for (wrcount=0; wrcount<count; ++wrcount) {
 227                 DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
 228                                 buf[wrcount]&0xff));
 229                 i2c_outb(adap, buf[wrcount]);
 230                 timeout = wait_for_pin(adap, &status);
 231                 if (timeout) {
 232                         if (timeout == -EINTR) {
 233                                 /* arbitration lost */
 234                                 return -EINTR;
 235                         }
 236                         i2c_stop(adap);
 237                         dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
 238                         return -EREMOTEIO; /* got a better one ?? */
 239                 }
 240 #ifndef STUB_I2C
 241                 if (status & I2C_PCF_LRB) {
 242                         i2c_stop(adap);
 243                         dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
 244                         return -EREMOTEIO; /* got a better one ?? */
 245                 }
 246 #endif
 247         }
 248         if (last) {
 249                 i2c_stop(adap);
 250         }
 251         else {
 252                 i2c_repstart(adap);
 253         }
 254
 255         return (wrcount);
 256 }
 257
 258
 259 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
 260                          int count, int last)
 261 {
 262         int i, status;
 263         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 264         int wfp;
 265
 266         /* increment number of bytes to read by one -- read dummy byte */
 267         for (i = 0; i <= count; i++) {
 268
 269                 if ((wfp = wait_for_pin(adap, &status))) {
 270                         if (wfp == -EINTR) {
 271                                 /* arbitration lost */
 272                                 return -EINTR;
 273                         }
 274                         i2c_stop(adap);
 275                         dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
 276                         return (-1);
 277                 }
 278
 279 #ifndef STUB_I2C
 280                 if ((status & I2C_PCF_LRB) && (i != count)) {
 281                         i2c_stop(adap);
 282                         dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
 283                         return (-1);
 284                 }
 285 #endif
 286
 287                 if (i == count - 1) {
 288                         set_pcf(adap, 1, I2C_PCF_ESO);
 289                 } else
 290                 if (i == count) {
 291                         if (last) {
 292                                 i2c_stop(adap);
 293                         } else {
 294                                 i2c_repstart(adap);
 295                         }
 296                 };
 297
 298                 if (i) {
 299                         buf[i - 1] = i2c_inb(adap);
 300                 } else {
 301                         i2c_inb(adap); /* dummy read */
 302                 }
 303         }
 304
 305         return (i - 1);
 306 }
 307
 308
 309 static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
 310                          struct i2c_msg *msg)
 311 {
 312         unsigned short flags = msg->flags;
 313         unsigned char addr;
 314
 315         addr = msg->addr << 1;
 316         if (flags & I2C_M_RD)
 317                 addr |= 1;
 318         if (flags & I2C_M_REV_DIR_ADDR)
 319                 addr ^= 1;
 320         i2c_outb(adap, addr);
 321
 322         return 0;
 323 }
 324
 325 static int pcf_xfer(struct i2c_adapter *i2c_adap,
 326                     struct i2c_msg *msgs,
 327                     int num)
 328 {
 329         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 330         struct i2c_msg *pmsg;
 331         int i;
 332         int ret=0, timeout, status;
 333
 334
 335         /* Check for bus busy */
 336         timeout = wait_for_bb(adap);
 337         if (timeout) {
 338                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
 339                             "Timeout waiting for BB in pcf_xfer\n");)
 340                 return -EIO;
 341         }
 342
 343         for (i = 0;ret >= 0 && i < num; i++) {
 344                 pmsg = &msgs[i];
 345
 346                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
 347                      pmsg->flags & I2C_M_RD ? "read" : "write",
 348                      pmsg->len, pmsg->addr, i + 1, num);)
 349
 350                 ret = pcf_doAddress(adap, pmsg);
 351
 352                 /* Send START */
 353                 if (i == 0) {
 354                         i2c_start(adap);
 355                 }
 356
 357                 /* Wait for PIN (pending interrupt NOT) */
 358                 timeout = wait_for_pin(adap, &status);
 359                 if (timeout) {
 360                         if (timeout == -EINTR) {
 361                                 /* arbitration lost */
 362                                 return (-EINTR);
 363                         }
 364                         i2c_stop(adap);
 365                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
 366                                     "for PIN(1) in pcf_xfer\n");)
 367                         return (-EREMOTEIO);
 368                 }
 369
 370 #ifndef STUB_I2C
 371                 /* Check LRB (last rcvd bit - slave ack) */
 372                 if (status & I2C_PCF_LRB) {
 373                         i2c_stop(adap);
 374                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
 375                         return (-EREMOTEIO);
 376                 }
 377 #endif
 378
 379                 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
 380                             i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
 381
 382                 /* Read */
 383                 if (pmsg->flags & I2C_M_RD) {
 384                         /* read bytes into buffer*/
 385                         ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
 386                                             (i + 1 == num));
 387
 388                         if (ret != pmsg->len) {
 389                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 390                                             "only read %d bytes.\n",ret));
 391                         } else {
 392                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
 393                         }
 394                 } else { /* Write */
 395                         ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
 396                                             (i + 1 == num));
 397
 398                         if (ret != pmsg->len) {
 399                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 400                                             "only wrote %d bytes.\n",ret));
 401                         } else {
 402                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
 403                         }
 404                 }
 405         }
 406
 407         return (i);
 408 }
 409
 410 static u32 pcf_func(struct i2c_adapter *adap)
 411 {
 412         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 413                I2C_FUNC_PROTOCOL_MANGLING;
 414 }
 415
 416 /* -----exported algorithm data: -------------------------------------  */
 417
 418 static const struct i2c_algorithm pcf_algo = {
 419         .master_xfer    = pcf_xfer,
 420         .functionality  = pcf_func,
 421 };
 422
 423 /*
 424  * registering functions to load algorithms at runtime
 425  */
 426 int i2c_pcf_add_bus(struct i2c_adapter *adap)
 427 {
 428         struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
 429         int rval;
 430
 431         DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
 432
 433         /* register new adapter to i2c module... */
 434         adap->algo = &pcf_algo;
 435         adap->timeout = 100;
 436
 437         if ((rval = pcf_init_8584(pcf_adap)))
 438                 return rval;
 439
 440         rval = i2c_add_adapter(adap);
 441
 442         return rval;
 443 }
 444 EXPORT_SYMBOL(i2c_pcf_add_bus);
 445
 446 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
 447 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
 448 MODULE_LICENSE("GPL");
 449
 450 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
 451 MODULE_PARM_DESC(i2c_debug,
 452         "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");