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., 51 Franklin Street, Fifth Floor, Boston,
  20  *  MA 02110-1301 USA.
  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, added detect code
  28  */
  29
  30 #include <linux/kernel.h>
  31 #include <linux/module.h>
  32 #include <linux/delay.h>
  33 #include <linux/errno.h>
  34 #include <linux/i2c.h>
  35 #include <linux/i2c-algo-pcf.h>
  36 #include "i2c-algo-pcf.h"
  37
  38
  39 #define DEB2(x) if (i2c_debug >= 2) x
  40 #define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */
  41 #define DEBPROTO(x) if (i2c_debug >= 9) x;
  42         /* debug the protocol by showing transferred bits */
  43 #define DEF_TIMEOUT 16
  44
  45 /*
  46  * module parameters:
  47  */
  48 static int i2c_debug;
  49
  50 /* setting states on the bus with the right timing: */
  51
  52 #define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
  53 #define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
  54 #define get_own(adap) adap->getown(adap->data)
  55 #define get_clock(adap) adap->getclock(adap->data)
  56 #define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
  57 #define i2c_inb(adap) adap->getpcf(adap->data, 0)
  58
  59 /* other auxiliary functions */
  60
  61 static void i2c_start(struct i2c_algo_pcf_data *adap)
  62 {
  63         DEBPROTO(printk(KERN_DEBUG "S "));
  64         set_pcf(adap, 1, I2C_PCF_START);
  65 }
  66
  67 static void i2c_repstart(struct i2c_algo_pcf_data *adap)
  68 {
  69         DEBPROTO(printk(" Sr "));
  70         set_pcf(adap, 1, I2C_PCF_REPSTART);
  71 }
  72
  73 static void i2c_stop(struct i2c_algo_pcf_data *adap)
  74 {
  75         DEBPROTO(printk("P\n"));
  76         set_pcf(adap, 1, I2C_PCF_STOP);
  77 }
  78
  79 static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
  80 {
  81         DEB2(printk(KERN_INFO
  82                 "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
  83                 *status));
  84         /*
  85          * Cleanup from LAB -- reset and enable ESO.
  86          * This resets the PCF8584; since we've lost the bus, no
  87          * further attempts should be made by callers to clean up
  88          * (no i2c_stop() etc.)
  89          */
  90         set_pcf(adap, 1, I2C_PCF_PIN);
  91         set_pcf(adap, 1, I2C_PCF_ESO);
  92         /*
  93          * We pause for a time period sufficient for any running
  94          * I2C transaction to complete -- the arbitration logic won't
  95          * work properly until the next START is seen.
  96          * It is assumed the bus driver or client has set a proper value.
  97          *
  98          * REVISIT: should probably use msleep instead of mdelay if we
  99          * know we can sleep.
 100          */
 101         if (adap->lab_mdelay)
 102                 mdelay(adap->lab_mdelay);
 103
 104         DEB2(printk(KERN_INFO
 105                 "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
 106                 get_pcf(adap, 1)));
 107 }
 108
 109 static int wait_for_bb(struct i2c_algo_pcf_data *adap)
 110 {
 111
 112         int timeout = DEF_TIMEOUT;
 113         int status;
 114
 115         status = get_pcf(adap, 1);
 116
 117         while (!(status & I2C_PCF_BB) && --timeout) {
 118                 udelay(100); /* wait for 100 us */
 119                 status = get_pcf(adap, 1);
 120         }
 121
 122         if (timeout == 0) {
 123                 printk(KERN_ERR "Timeout waiting for Bus Busy\n");
 124                 return -ETIMEDOUT;
 125         }
 126
 127         return 0;
 128 }
 129
 130 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
 131 {
 132
 133         int timeout = DEF_TIMEOUT;
 134
 135         *status = get_pcf(adap, 1);
 136
 137         while ((*status & I2C_PCF_PIN) && --timeout) {
 138                 adap->waitforpin(adap->data);
 139                 *status = get_pcf(adap, 1);
 140         }
 141         if (*status & I2C_PCF_LAB) {
 142                 handle_lab(adap, status);
 143                 return -EINTR;
 144         }
 145
 146         if (timeout == 0)
 147                 return -ETIMEDOUT;
 148
 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",
 168                                 get_pcf(adap, 1)));
 169
 170         /* S1=0x80: S0 selected, serial interface off */
 171         set_pcf(adap, 1, I2C_PCF_PIN);
 172         /*
 173          * check to see S1 now used as R/W ctrl -
 174          * PCF8584 does that when ESO is zero
 175          */
 176         if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
 177                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
 178                 return -ENXIO; /* definitely not PCF8584 */
 179         }
 180
 181         /* load own address in S0, effective address is (own << 1) */
 182         i2c_outb(adap, get_own(adap));
 183         /* check it's really written */
 184         if ((temp = i2c_inb(adap)) != get_own(adap)) {
 185                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
 186                 return -ENXIO;
 187         }
 188
 189         /* S1=0xA0, next byte in S2 */
 190         set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
 191         /* check to see S2 now selected */
 192         if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
 193                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
 194                 return -ENXIO;
 195         }
 196
 197         /* load clock register S2 */
 198         i2c_outb(adap, get_clock(adap));
 199         /* check it's really written, the only 5 lowest bits does matter */
 200         if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
 201                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
 202                 return -ENXIO;
 203         }
 204
 205         /* Enable serial interface, idle, S0 selected */
 206         set_pcf(adap, 1, I2C_PCF_IDLE);
 207
 208         /* check to see PCF is really idled and we can access status register */
 209         if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
 210                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
 211                 return -ENXIO;
 212         }
 213
 214         printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");
 215
 216         return 0;
 217 }
 218
 219 static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
 220                          int count, int last)
 221 {
 222         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 223         int wrcount, status, timeout;
 224
 225         for (wrcount=0; wrcount<count; ++wrcount) {
 226                 DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
 227                                 buf[wrcount] & 0xff));
 228                 i2c_outb(adap, buf[wrcount]);
 229                 timeout = wait_for_pin(adap, &status);
 230                 if (timeout) {
 231                         if (timeout == -EINTR)
 232                                 return -EINTR; /* arbitration lost */
 233
 234                         i2c_stop(adap);
 235                         dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
 236                         return -EREMOTEIO; /* got a better one ?? */
 237                 }
 238                 if (status & I2C_PCF_LRB) {
 239                         i2c_stop(adap);
 240                         dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
 241                         return -EREMOTEIO; /* got a better one ?? */
 242                 }
 243         }
 244         if (last)
 245                 i2c_stop(adap);
 246         else
 247                 i2c_repstart(adap);
 248
 249         return wrcount;
 250 }
 251
 252 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
 253                          int count, int last)
 254 {
 255         int i, status;
 256         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 257         int wfp;
 258
 259         /* increment number of bytes to read by one -- read dummy byte */
 260         for (i = 0; i <= count; i++) {
 261
 262                 if ((wfp = wait_for_pin(adap, &status))) {
 263                         if (wfp == -EINTR)
 264                                 return -EINTR; /* arbitration lost */
 265
 266                         i2c_stop(adap);
 267                         dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
 268                         return -1;
 269                 }
 270
 271                 if ((status & I2C_PCF_LRB) && (i != count)) {
 272                         i2c_stop(adap);
 273                         dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
 274                         return -1;
 275                 }
 276
 277                 if (i == count - 1) {
 278                         set_pcf(adap, 1, I2C_PCF_ESO);
 279                 } else if (i == count) {
 280                         if (last)
 281                                 i2c_stop(adap);
 282                         else
 283                                 i2c_repstart(adap);
 284                 }
 285
 286                 if (i)
 287                         buf[i - 1] = i2c_inb(adap);
 288                 else
 289                         i2c_inb(adap); /* dummy read */
 290         }
 291
 292         return i - 1;
 293 }
 294
 295
 296 static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
 297                          struct i2c_msg *msg)
 298 {
 299         unsigned short flags = msg->flags;
 300         unsigned char addr;
 301
 302         addr = msg->addr << 1;
 303         if (flags & I2C_M_RD)
 304                 addr |= 1;
 305         if (flags & I2C_M_REV_DIR_ADDR)
 306                 addr ^= 1;
 307         i2c_outb(adap, addr);
 308
 309         return 0;
 310 }
 311
 312 static int pcf_xfer(struct i2c_adapter *i2c_adap,
 313                     struct i2c_msg *msgs,
 314                     int num)
 315 {
 316         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 317         struct i2c_msg *pmsg;
 318         int i;
 319         int ret=0, timeout, status;
 320
 321         if (adap->xfer_begin)
 322                 adap->xfer_begin(adap->data);
 323
 324         /* Check for bus busy */
 325         timeout = wait_for_bb(adap);
 326         if (timeout) {
 327                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
 328                             "Timeout waiting for BB in pcf_xfer\n");)
 329                 i = -EIO;
 330                 goto out;
 331         }
 332
 333         for (i = 0;ret >= 0 && i < num; i++) {
 334                 pmsg = &msgs[i];
 335
 336                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
 337                      pmsg->flags & I2C_M_RD ? "read" : "write",
 338                      pmsg->len, pmsg->addr, i + 1, num);)
 339
 340                 ret = pcf_doAddress(adap, pmsg);
 341
 342                 /* Send START */
 343                 if (i == 0)
 344                         i2c_start(adap);
 345
 346                 /* Wait for PIN (pending interrupt NOT) */
 347                 timeout = wait_for_pin(adap, &status);
 348                 if (timeout) {
 349                         if (timeout == -EINTR) {
 350                                 /* arbitration lost */
 351                                 i = -EINTR;
 352                                 goto out;
 353                         }
 354                         i2c_stop(adap);
 355                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
 356                                     "for PIN(1) in pcf_xfer\n");)
 357                         i = -EREMOTEIO;
 358                         goto out;
 359                 }
 360
 361                 /* Check LRB (last rcvd bit - slave ack) */
 362                 if (status & I2C_PCF_LRB) {
 363                         i2c_stop(adap);
 364                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
 365                         i = -EREMOTEIO;
 366                         goto out;
 367                 }
 368
 369                 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
 370                             i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
 371
 372                 if (pmsg->flags & I2C_M_RD) {
 373                         ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
 374                                             (i + 1 == num));
 375
 376                         if (ret != pmsg->len) {
 377                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 378                                             "only read %d bytes.\n",ret));
 379                         } else {
 380                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
 381                         }
 382                 } else {
 383                         ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
 384                                             (i + 1 == num));
 385
 386                         if (ret != pmsg->len) {
 387                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 388                                             "only wrote %d bytes.\n",ret));
 389                         } else {
 390                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
 391                         }
 392                 }
 393         }
 394
 395 out:
 396         if (adap->xfer_end)
 397                 adap->xfer_end(adap->data);
 398         return i;
 399 }
 400
 401 static u32 pcf_func(struct i2c_adapter *adap)
 402 {
 403         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 404                I2C_FUNC_PROTOCOL_MANGLING;
 405 }
 406
 407 /* exported algorithm data: */
 408 static const struct i2c_algorithm pcf_algo = {
 409         .master_xfer    = pcf_xfer,
 410         .functionality  = pcf_func,
 411 };
 412
 413 /*
 414  * registering functions to load algorithms at runtime
 415  */
 416 int i2c_pcf_add_bus(struct i2c_adapter *adap)
 417 {
 418         struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
 419         int rval;
 420
 421         DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
 422
 423         /* register new adapter to i2c module... */
 424         adap->algo = &pcf_algo;
 425
 426         if ((rval = pcf_init_8584(pcf_adap)))
 427                 return rval;
 428
 429         rval = i2c_add_adapter(adap);
 430
 431         return rval;
 432 }
 433 EXPORT_SYMBOL(i2c_pcf_add_bus);
 434
 435 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
 436 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
 437 MODULE_LICENSE("GPL");
 438
 439 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
 440 MODULE_PARM_DESC(i2c_debug,
 441         "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");