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 int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
 207                          int count, int last)
 208 {
 209         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 210         int wrcount, status, timeout;
 211
 212         for (wrcount=0; wrcount<count; ++wrcount) {
 213                 DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
 214                                 buf[wrcount]&0xff));
 215                 i2c_outb(adap, buf[wrcount]);
 216                 timeout = wait_for_pin(adap, &status);
 217                 if (timeout) {
 218                         if (timeout == -EINTR) {
 219                                 /* arbitration lost */
 220                                 return -EINTR;
 221                         }
 222                         i2c_stop(adap);
 223                         dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
 224                         return -EREMOTEIO; /* got a better one ?? */
 225                 }
 226 #ifndef STUB_I2C
 227                 if (status & I2C_PCF_LRB) {
 228                         i2c_stop(adap);
 229                         dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
 230                         return -EREMOTEIO; /* got a better one ?? */
 231                 }
 232 #endif
 233         }
 234         if (last) {
 235                 i2c_stop(adap);
 236         }
 237         else {
 238                 i2c_repstart(adap);
 239         }
 240
 241         return (wrcount);
 242 }
 243
 244
 245 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
 246                          int count, int last)
 247 {
 248         int i, status;
 249         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 250         int wfp;
 251
 252         /* increment number of bytes to read by one -- read dummy byte */
 253         for (i = 0; i <= count; i++) {
 254
 255                 if ((wfp = wait_for_pin(adap, &status))) {
 256                         if (wfp == -EINTR) {
 257                                 /* arbitration lost */
 258                                 return -EINTR;
 259                         }
 260                         i2c_stop(adap);
 261                         dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
 262                         return (-1);
 263                 }
 264
 265 #ifndef STUB_I2C
 266                 if ((status & I2C_PCF_LRB) && (i != count)) {
 267                         i2c_stop(adap);
 268                         dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
 269                         return (-1);
 270                 }
 271 #endif
 272
 273                 if (i == count - 1) {
 274                         set_pcf(adap, 1, I2C_PCF_ESO);
 275                 } else
 276                 if (i == count) {
 277                         if (last) {
 278                                 i2c_stop(adap);
 279                         } else {
 280                                 i2c_repstart(adap);
 281                         }
 282                 };
 283
 284                 if (i) {
 285                         buf[i - 1] = i2c_inb(adap);
 286                 } else {
 287                         i2c_inb(adap); /* dummy read */
 288                 }
 289         }
 290
 291         return (i - 1);
 292 }
 293
 294
 295 static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
 296                          struct i2c_msg *msg)
 297 {
 298         unsigned short flags = msg->flags;
 299         unsigned char addr;
 300
 301         addr = msg->addr << 1;
 302         if (flags & I2C_M_RD)
 303                 addr |= 1;
 304         if (flags & I2C_M_REV_DIR_ADDR)
 305                 addr ^= 1;
 306         i2c_outb(adap, addr);
 307
 308         return 0;
 309 }
 310
 311 static int pcf_xfer(struct i2c_adapter *i2c_adap,
 312                     struct i2c_msg *msgs,
 313                     int num)
 314 {
 315         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 316         struct i2c_msg *pmsg;
 317         int i;
 318         int ret=0, timeout, status;
 319
 320
 321         /* Check for bus busy */
 322         timeout = wait_for_bb(adap);
 323         if (timeout) {
 324                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
 325                             "Timeout waiting for BB in pcf_xfer\n");)
 326                 return -EIO;
 327         }
 328
 329         for (i = 0;ret >= 0 && i < num; i++) {
 330                 pmsg = &msgs[i];
 331
 332                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
 333                      pmsg->flags & I2C_M_RD ? "read" : "write",
 334                      pmsg->len, pmsg->addr, i + 1, num);)
 335
 336                 ret = pcf_doAddress(adap, pmsg);
 337
 338                 /* Send START */
 339                 if (i == 0) {
 340                         i2c_start(adap);
 341                 }
 342
 343                 /* Wait for PIN (pending interrupt NOT) */
 344                 timeout = wait_for_pin(adap, &status);
 345                 if (timeout) {
 346                         if (timeout == -EINTR) {
 347                                 /* arbitration lost */
 348                                 return (-EINTR);
 349                         }
 350                         i2c_stop(adap);
 351                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
 352                                     "for PIN(1) in pcf_xfer\n");)
 353                         return (-EREMOTEIO);
 354                 }
 355
 356 #ifndef STUB_I2C
 357                 /* Check LRB (last rcvd bit - slave ack) */
 358                 if (status & I2C_PCF_LRB) {
 359                         i2c_stop(adap);
 360                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
 361                         return (-EREMOTEIO);
 362                 }
 363 #endif
 364
 365                 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
 366                             i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
 367
 368                 /* Read */
 369                 if (pmsg->flags & I2C_M_RD) {
 370                         /* read bytes into buffer*/
 371                         ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
 372                                             (i + 1 == num));
 373
 374                         if (ret != pmsg->len) {
 375                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 376                                             "only read %d bytes.\n",ret));
 377                         } else {
 378                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
 379                         }
 380                 } else { /* Write */
 381                         ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
 382                                             (i + 1 == num));
 383
 384                         if (ret != pmsg->len) {
 385                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 386                                             "only wrote %d bytes.\n",ret));
 387                         } else {
 388                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
 389                         }
 390                 }
 391         }
 392
 393         return (i);
 394 }
 395
 396 static u32 pcf_func(struct i2c_adapter *adap)
 397 {
 398         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 399                I2C_FUNC_PROTOCOL_MANGLING;
 400 }
 401
 402 /* -----exported algorithm data: -------------------------------------  */
 403
 404 static const struct i2c_algorithm pcf_algo = {
 405         .master_xfer    = pcf_xfer,
 406         .functionality  = pcf_func,
 407 };
 408
 409 /*
 410  * registering functions to load algorithms at runtime
 411  */
 412 int i2c_pcf_add_bus(struct i2c_adapter *adap)
 413 {
 414         struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
 415         int rval;
 416
 417         DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
 418
 419         /* register new adapter to i2c module... */
 420         adap->algo = &pcf_algo;
 421         adap->timeout = 100;
 422
 423         if ((rval = pcf_init_8584(pcf_adap)))
 424                 return rval;
 425
 426         rval = i2c_add_adapter(adap);
 427
 428         return rval;
 429 }
 430 EXPORT_SYMBOL(i2c_pcf_add_bus);
 431
 432 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
 433 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
 434 MODULE_LICENSE("GPL");
 435
 436 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
 437 MODULE_PARM_DESC(i2c_debug,
 438         "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");