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  * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
  22  * Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey
  23  * <mbailey@littlefeet-inc.com>
  24  *
  25  * Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
  26  * messages, proper stop/repstart signaling during receive, added detect code
  27  */
  28
  29 #include <linux/kernel.h>
  30 #include <linux/module.h>
  31 #include <linux/delay.h>
  32 #include <linux/slab.h>
  33 #include <linux/init.h>
  34 #include <linux/errno.h>
  35 #include <linux/i2c.h>
  36 #include <linux/i2c-algo-pcf.h>
  37 #include "i2c-algo-pcf.h"
  38
  39
  40 #define DEB2(x) if (i2c_debug >= 2) x
  41 #define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */
  42 #define DEBPROTO(x) if (i2c_debug >= 9) x;
  43         /* debug the protocol by showing transferred bits */
  44 #define DEF_TIMEOUT 16
  45
  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(KERN_DEBUG "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 static void i2c_stop(struct i2c_algo_pcf_data *adap)
  75 {
  76         DEBPROTO(printk("P\n"));
  77         set_pcf(adap, 1, I2C_PCF_STOP);
  78 }
  79
  80 static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
  81 {
  82         DEB2(printk(KERN_INFO
  83                 "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
  84                 *status));
  85         /*
  86          * Cleanup from LAB -- reset and enable ESO.
  87          * This resets the PCF8584; since we've lost the bus, no
  88          * further attempts should be made by callers to clean up
  89          * (no i2c_stop() etc.)
  90          */
  91         set_pcf(adap, 1, I2C_PCF_PIN);
  92         set_pcf(adap, 1, I2C_PCF_ESO);
  93         /*
  94          * We pause for a time period sufficient for any running
  95          * I2C transaction to complete -- the arbitration logic won't
  96          * work properly until the next START is seen.
  97          * It is assumed the bus driver or client has set a proper value.
  98          *
  99          * REVISIT: should probably use msleep instead of mdelay if we
 100          * know we can sleep.
 101          */
 102         if (adap->lab_mdelay)
 103                 mdelay(adap->lab_mdelay);
 104
 105         DEB2(printk(KERN_INFO
 106                 "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
 107                 get_pcf(adap, 1)));
 108 }
 109
 110 static int wait_for_bb(struct i2c_algo_pcf_data *adap)
 111 {
 112
 113         int timeout = DEF_TIMEOUT;
 114         int status;
 115
 116         status = get_pcf(adap, 1);
 117
 118         while (!(status & I2C_PCF_BB) && --timeout) {
 119                 udelay(100); /* wait for 100 us */
 120                 status = get_pcf(adap, 1);
 121         }
 122
 123         if (timeout == 0) {
 124                 printk(KERN_ERR "Timeout waiting for Bus Busy\n");
 125                 return -ETIMEDOUT;
 126         }
 127
 128         return 0;
 129 }
 130
 131 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
 132 {
 133
 134         int timeout = DEF_TIMEOUT;
 135
 136         *status = get_pcf(adap, 1);
 137
 138         while ((*status & I2C_PCF_PIN) && --timeout) {
 139                 adap->waitforpin(adap->data);
 140                 *status = get_pcf(adap, 1);
 141         }
 142         if (*status & I2C_PCF_LAB) {
 143                 handle_lab(adap, status);
 144                 return -EINTR;
 145         }
 146
 147         if (timeout == 0)
 148                 return -ETIMEDOUT;
 149
 150         return 0;
 151 }
 152
 153 /*
 154  * This should perform the 'PCF8584 initialization sequence' as described
 155  * in the Philips IC12 data book (1995, Aug 29).
 156  * There should be a 30 clock cycle wait after reset, I assume this
 157  * has been fulfilled.
 158  * There should be a delay at the end equal to the longest I2C message
 159  * to synchronize the BB-bit (in multimaster systems). How long is
 160  * this? I assume 1 second is always long enough.
 161  *
 162  * vdovikin: added detect code for PCF8584
 163  */
 164 static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
 165 {
 166         unsigned char temp;
 167
 168         DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n",
 169                                 get_pcf(adap, 1)));
 170
 171         /* S1=0x80: S0 selected, serial interface off */
 172         set_pcf(adap, 1, I2C_PCF_PIN);
 173         /*
 174          * check to see S1 now used as R/W ctrl -
 175          * PCF8584 does that when ESO is zero
 176          */
 177         if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
 178                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
 179                 return -ENXIO; /* definetly not PCF8584 */
 180         }
 181
 182         /* load own address in S0, effective address is (own << 1) */
 183         i2c_outb(adap, get_own(adap));
 184         /* check it's really written */
 185         if ((temp = i2c_inb(adap)) != get_own(adap)) {
 186                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
 187                 return -ENXIO;
 188         }
 189
 190         /* S1=0xA0, next byte in S2 */
 191         set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
 192         /* check to see S2 now selected */
 193         if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
 194                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
 195                 return -ENXIO;
 196         }
 197
 198         /* load clock register S2 */
 199         i2c_outb(adap, get_clock(adap));
 200         /* check it's really written, the only 5 lowest bits does matter */
 201         if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
 202                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
 203                 return -ENXIO;
 204         }
 205
 206         /* Enable serial interface, idle, S0 selected */
 207         set_pcf(adap, 1, I2C_PCF_IDLE);
 208
 209         /* check to see PCF is really idled and we can access status register */
 210         if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
 211                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
 212                 return -ENXIO;
 213         }
 214
 215         printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");
 216
 217         return 0;
 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                                 return -EINTR; /* arbitration lost */
 234
 235                         i2c_stop(adap);
 236                         dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
 237                         return -EREMOTEIO; /* got a better one ?? */
 238                 }
 239                 if (status & I2C_PCF_LRB) {
 240                         i2c_stop(adap);
 241                         dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
 242                         return -EREMOTEIO; /* got a better one ?? */
 243                 }
 244         }
 245         if (last)
 246                 i2c_stop(adap);
 247         else
 248                 i2c_repstart(adap);
 249
 250         return wrcount;
 251 }
 252
 253 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
 254                          int count, int last)
 255 {
 256         int i, status;
 257         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 258         int wfp;
 259
 260         /* increment number of bytes to read by one -- read dummy byte */
 261         for (i = 0; i <= count; i++) {
 262
 263                 if ((wfp = wait_for_pin(adap, &status))) {
 264                         if (wfp == -EINTR)
 265                                 return -EINTR; /* arbitration lost */
 266
 267                         i2c_stop(adap);
 268                         dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
 269                         return -1;
 270                 }
 271
 272                 if ((status & I2C_PCF_LRB) && (i != count)) {
 273                         i2c_stop(adap);
 274                         dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
 275                         return -1;
 276                 }
 277
 278                 if (i == count - 1) {
 279                         set_pcf(adap, 1, I2C_PCF_ESO);
 280                 } else if (i == count) {
 281                         if (last)
 282                                 i2c_stop(adap);
 283                         else
 284                                 i2c_repstart(adap);
 285                 }
 286
 287                 if (i)
 288                         buf[i - 1] = i2c_inb(adap);
 289                 else
 290                         i2c_inb(adap); /* dummy read */
 291         }
 292
 293         return i - 1;
 294 }
 295
 296
 297 static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
 298                          struct i2c_msg *msg)
 299 {
 300         unsigned short flags = msg->flags;
 301         unsigned char addr;
 302
 303         addr = msg->addr << 1;
 304         if (flags & I2C_M_RD)
 305                 addr |= 1;
 306         if (flags & I2C_M_REV_DIR_ADDR)
 307                 addr ^= 1;
 308         i2c_outb(adap, addr);
 309
 310         return 0;
 311 }
 312
 313 static int pcf_xfer(struct i2c_adapter *i2c_adap,
 314                     struct i2c_msg *msgs,
 315                     int num)
 316 {
 317         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 318         struct i2c_msg *pmsg;
 319         int i;
 320         int ret=0, timeout, status;
 321
 322         if (adap->xfer_begin)
 323                 adap->xfer_begin(adap->data);
 324
 325         /* Check for bus busy */
 326         timeout = wait_for_bb(adap);
 327         if (timeout) {
 328                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
 329                             "Timeout waiting for BB in pcf_xfer\n");)
 330                 i = -EIO;
 331                 goto out;
 332         }
 333
 334         for (i = 0;ret >= 0 && i < num; i++) {
 335                 pmsg = &msgs[i];
 336
 337                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
 338                      pmsg->flags & I2C_M_RD ? "read" : "write",
 339                      pmsg->len, pmsg->addr, i + 1, num);)
 340
 341                 ret = pcf_doAddress(adap, pmsg);
 342
 343                 /* Send START */
 344                 if (i == 0)
 345                         i2c_start(adap);
 346
 347                 /* Wait for PIN (pending interrupt NOT) */
 348                 timeout = wait_for_pin(adap, &status);
 349                 if (timeout) {
 350                         if (timeout == -EINTR) {
 351                                 /* arbitration lost */
 352                                 i = -EINTR;
 353                                 goto out;
 354                         }
 355                         i2c_stop(adap);
 356                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
 357                                     "for PIN(1) in pcf_xfer\n");)
 358                         i = -EREMOTEIO;
 359                         goto out;
 360                 }
 361
 362                 /* Check LRB (last rcvd bit - slave ack) */
 363                 if (status & I2C_PCF_LRB) {
 364                         i2c_stop(adap);
 365                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
 366                         i = -EREMOTEIO;
 367                         goto out;
 368                 }
 369
 370                 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
 371                             i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
 372
 373                 if (pmsg->flags & I2C_M_RD) {
 374                         ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
 375                                             (i + 1 == num));
 376
 377                         if (ret != pmsg->len) {
 378                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 379                                             "only read %d bytes.\n",ret));
 380                         } else {
 381                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
 382                         }
 383                 } else {
 384                         ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
 385                                             (i + 1 == num));
 386
 387                         if (ret != pmsg->len) {
 388                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 389                                             "only wrote %d bytes.\n",ret));
 390                         } else {
 391                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
 392                         }
 393                 }
 394         }
 395
 396 out:
 397         if (adap->xfer_end)
 398                 adap->xfer_end(adap->data);
 399         return i;
 400 }
 401
 402 static u32 pcf_func(struct i2c_adapter *adap)
 403 {
 404         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 405                I2C_FUNC_PROTOCOL_MANGLING;
 406 }
 407
 408 /* exported algorithm data: */
 409 static const struct i2c_algorithm pcf_algo = {
 410         .master_xfer    = pcf_xfer,
 411         .functionality  = pcf_func,
 412 };
 413
 414 /*
 415  * registering functions to load algorithms at runtime
 416  */
 417 int i2c_pcf_add_bus(struct i2c_adapter *adap)
 418 {
 419         struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
 420         int rval;
 421
 422         DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
 423
 424         /* register new adapter to i2c module... */
 425         adap->algo = &pcf_algo;
 426
 427         if ((rval = pcf_init_8584(pcf_adap)))
 428                 return rval;
 429
 430         rval = i2c_add_adapter(adap);
 431
 432         return rval;
 433 }
 434 EXPORT_SYMBOL(i2c_pcf_add_bus);
 435
 436 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
 437 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
 438 MODULE_LICENSE("GPL");
 439
 440 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
 441 MODULE_PARM_DESC(i2c_debug,
 442         "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");