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  * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
  18  * Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey
  19  * <mbailey@littlefeet-inc.com>
  20  *
  21  * Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
  22  * messages, proper stop/repstart signaling during receive, added detect code
  23  */
  24
  25 #include <linux/kernel.h>
  26 #include <linux/module.h>
  27 #include <linux/delay.h>
  28 #include <linux/errno.h>
  29 #include <linux/i2c.h>
  30 #include <linux/i2c-algo-pcf.h>
  31 #include "i2c-algo-pcf.h"
  32
  33
  34 #define DEB2(x) if (i2c_debug >= 2) x
  35 #define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */
  36 #define DEBPROTO(x) if (i2c_debug >= 9) x;
  37         /* debug the protocol by showing transferred bits */
  38 #define DEF_TIMEOUT 16
  39
  40 /*
  41  * module parameters:
  42  */
  43 static int i2c_debug;
  44
  45 /* setting states on the bus with the right timing: */
  46
  47 #define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
  48 #define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
  49 #define get_own(adap) adap->getown(adap->data)
  50 #define get_clock(adap) adap->getclock(adap->data)
  51 #define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
  52 #define i2c_inb(adap) adap->getpcf(adap->data, 0)
  53
  54 /* other auxiliary functions */
  55
  56 static void i2c_start(struct i2c_algo_pcf_data *adap)
  57 {
  58         DEBPROTO(printk(KERN_DEBUG "S "));
  59         set_pcf(adap, 1, I2C_PCF_START);
  60 }
  61
  62 static void i2c_repstart(struct i2c_algo_pcf_data *adap)
  63 {
  64         DEBPROTO(printk(" Sr "));
  65         set_pcf(adap, 1, I2C_PCF_REPSTART);
  66 }
  67
  68 static void i2c_stop(struct i2c_algo_pcf_data *adap)
  69 {
  70         DEBPROTO(printk("P\n"));
  71         set_pcf(adap, 1, I2C_PCF_STOP);
  72 }
  73
  74 static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
  75 {
  76         DEB2(printk(KERN_INFO
  77                 "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
  78                 *status));
  79         /*
  80          * Cleanup from LAB -- reset and enable ESO.
  81          * This resets the PCF8584; since we've lost the bus, no
  82          * further attempts should be made by callers to clean up
  83          * (no i2c_stop() etc.)
  84          */
  85         set_pcf(adap, 1, I2C_PCF_PIN);
  86         set_pcf(adap, 1, I2C_PCF_ESO);
  87         /*
  88          * We pause for a time period sufficient for any running
  89          * I2C transaction to complete -- the arbitration logic won't
  90          * work properly until the next START is seen.
  91          * It is assumed the bus driver or client has set a proper value.
  92          *
  93          * REVISIT: should probably use msleep instead of mdelay if we
  94          * know we can sleep.
  95          */
  96         if (adap->lab_mdelay)
  97                 mdelay(adap->lab_mdelay);
  98
  99         DEB2(printk(KERN_INFO
 100                 "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
 101                 get_pcf(adap, 1)));
 102 }
 103
 104 static int wait_for_bb(struct i2c_algo_pcf_data *adap)
 105 {
 106
 107         int timeout = DEF_TIMEOUT;
 108         int status;
 109
 110         status = get_pcf(adap, 1);
 111
 112         while (!(status & I2C_PCF_BB) && --timeout) {
 113                 udelay(100); /* wait for 100 us */
 114                 status = get_pcf(adap, 1);
 115         }
 116
 117         if (timeout == 0) {
 118                 printk(KERN_ERR "Timeout waiting for Bus Busy\n");
 119                 return -ETIMEDOUT;
 120         }
 121
 122         return 0;
 123 }
 124
 125 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
 126 {
 127
 128         int timeout = DEF_TIMEOUT;
 129
 130         *status = get_pcf(adap, 1);
 131
 132         while ((*status & I2C_PCF_PIN) && --timeout) {
 133                 adap->waitforpin(adap->data);
 134                 *status = get_pcf(adap, 1);
 135         }
 136         if (*status & I2C_PCF_LAB) {
 137                 handle_lab(adap, status);
 138                 return -EINTR;
 139         }
 140
 141         if (timeout == 0)
 142                 return -ETIMEDOUT;
 143
 144         return 0;
 145 }
 146
 147 /*
 148  * This should perform the 'PCF8584 initialization sequence' as described
 149  * in the Philips IC12 data book (1995, Aug 29).
 150  * There should be a 30 clock cycle wait after reset, I assume this
 151  * has been fulfilled.
 152  * There should be a delay at the end equal to the longest I2C message
 153  * to synchronize the BB-bit (in multimaster systems). How long is
 154  * this? I assume 1 second is always long enough.
 155  *
 156  * vdovikin: added detect code for PCF8584
 157  */
 158 static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
 159 {
 160         unsigned char temp;
 161
 162         DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n",
 163                                 get_pcf(adap, 1)));
 164
 165         /* S1=0x80: S0 selected, serial interface off */
 166         set_pcf(adap, 1, I2C_PCF_PIN);
 167         /*
 168          * check to see S1 now used as R/W ctrl -
 169          * PCF8584 does that when ESO is zero
 170          */
 171         if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
 172                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
 173                 return -ENXIO; /* definitely not PCF8584 */
 174         }
 175
 176         /* load own address in S0, effective address is (own << 1) */
 177         i2c_outb(adap, get_own(adap));
 178         /* check it's really written */
 179         if ((temp = i2c_inb(adap)) != get_own(adap)) {
 180                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
 181                 return -ENXIO;
 182         }
 183
 184         /* S1=0xA0, next byte in S2 */
 185         set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
 186         /* check to see S2 now selected */
 187         if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
 188                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
 189                 return -ENXIO;
 190         }
 191
 192         /* load clock register S2 */
 193         i2c_outb(adap, get_clock(adap));
 194         /* check it's really written, the only 5 lowest bits does matter */
 195         if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
 196                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
 197                 return -ENXIO;
 198         }
 199
 200         /* Enable serial interface, idle, S0 selected */
 201         set_pcf(adap, 1, I2C_PCF_IDLE);
 202
 203         /* check to see PCF is really idled and we can access status register */
 204         if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
 205                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
 206                 return -ENXIO;
 207         }
 208
 209         printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");
 210
 211         return 0;
 212 }
 213
 214 static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
 215                          int count, int last)
 216 {
 217         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 218         int wrcount, status, timeout;
 219
 220         for (wrcount=0; wrcount<count; ++wrcount) {
 221                 DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
 222                                 buf[wrcount] & 0xff));
 223                 i2c_outb(adap, buf[wrcount]);
 224                 timeout = wait_for_pin(adap, &status);
 225                 if (timeout) {
 226                         if (timeout == -EINTR)
 227                                 return -EINTR; /* arbitration lost */
 228
 229                         i2c_stop(adap);
 230                         dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
 231                         return -EREMOTEIO; /* got a better one ?? */
 232                 }
 233                 if (status & I2C_PCF_LRB) {
 234                         i2c_stop(adap);
 235                         dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
 236                         return -EREMOTEIO; /* got a better one ?? */
 237                 }
 238         }
 239         if (last)
 240                 i2c_stop(adap);
 241         else
 242                 i2c_repstart(adap);
 243
 244         return wrcount;
 245 }
 246
 247 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
 248                          int count, int last)
 249 {
 250         int i, status;
 251         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 252         int wfp;
 253
 254         /* increment number of bytes to read by one -- read dummy byte */
 255         for (i = 0; i <= count; i++) {
 256
 257                 if ((wfp = wait_for_pin(adap, &status))) {
 258                         if (wfp == -EINTR)
 259                                 return -EINTR; /* arbitration lost */
 260
 261                         i2c_stop(adap);
 262                         dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
 263                         return -1;
 264                 }
 265
 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
 272                 if (i == count - 1) {
 273                         set_pcf(adap, 1, I2C_PCF_ESO);
 274                 } else if (i == count) {
 275                         if (last)
 276                                 i2c_stop(adap);
 277                         else
 278                                 i2c_repstart(adap);
 279                 }
 280
 281                 if (i)
 282                         buf[i - 1] = i2c_inb(adap);
 283                 else
 284                         i2c_inb(adap); /* dummy read */
 285         }
 286
 287         return i - 1;
 288 }
 289
 290
 291 static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
 292                          struct i2c_msg *msg)
 293 {
 294         unsigned short flags = msg->flags;
 295         unsigned char addr;
 296
 297         addr = msg->addr << 1;
 298         if (flags & I2C_M_RD)
 299                 addr |= 1;
 300         if (flags & I2C_M_REV_DIR_ADDR)
 301                 addr ^= 1;
 302         i2c_outb(adap, addr);
 303
 304         return 0;
 305 }
 306
 307 static int pcf_xfer(struct i2c_adapter *i2c_adap,
 308                     struct i2c_msg *msgs,
 309                     int num)
 310 {
 311         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 312         struct i2c_msg *pmsg;
 313         int i;
 314         int ret=0, timeout, status;
 315
 316         if (adap->xfer_begin)
 317                 adap->xfer_begin(adap->data);
 318
 319         /* Check for bus busy */
 320         timeout = wait_for_bb(adap);
 321         if (timeout) {
 322                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
 323                             "Timeout waiting for BB in pcf_xfer\n");)
 324                 i = -EIO;
 325                 goto out;
 326         }
 327
 328         for (i = 0;ret >= 0 && i < num; i++) {
 329                 pmsg = &msgs[i];
 330
 331                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
 332                      pmsg->flags & I2C_M_RD ? "read" : "write",
 333                      pmsg->len, pmsg->addr, i + 1, num);)
 334
 335                 ret = pcf_doAddress(adap, pmsg);
 336
 337                 /* Send START */
 338                 if (i == 0)
 339                         i2c_start(adap);
 340
 341                 /* Wait for PIN (pending interrupt NOT) */
 342                 timeout = wait_for_pin(adap, &status);
 343                 if (timeout) {
 344                         if (timeout == -EINTR) {
 345                                 /* arbitration lost */
 346                                 i = -EINTR;
 347                                 goto out;
 348                         }
 349                         i2c_stop(adap);
 350                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
 351                                     "for PIN(1) in pcf_xfer\n");)
 352                         i = -EREMOTEIO;
 353                         goto out;
 354                 }
 355
 356                 /* Check LRB (last rcvd bit - slave ack) */
 357                 if (status & I2C_PCF_LRB) {
 358                         i2c_stop(adap);
 359                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
 360                         i = -EREMOTEIO;
 361                         goto out;
 362                 }
 363
 364                 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
 365                             i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
 366
 367                 if (pmsg->flags & I2C_M_RD) {
 368                         ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
 369                                             (i + 1 == num));
 370
 371                         if (ret != pmsg->len) {
 372                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 373                                             "only read %d bytes.\n",ret));
 374                         } else {
 375                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
 376                         }
 377                 } else {
 378                         ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
 379                                             (i + 1 == num));
 380
 381                         if (ret != pmsg->len) {
 382                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 383                                             "only wrote %d bytes.\n",ret));
 384                         } else {
 385                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
 386                         }
 387                 }
 388         }
 389
 390 out:
 391         if (adap->xfer_end)
 392                 adap->xfer_end(adap->data);
 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 static const struct i2c_algorithm pcf_algo = {
 404         .master_xfer    = pcf_xfer,
 405         .functionality  = pcf_func,
 406 };
 407
 408 /*
 409  * registering functions to load algorithms at runtime
 410  */
 411 int i2c_pcf_add_bus(struct i2c_adapter *adap)
 412 {
 413         struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
 414         int rval;
 415
 416         DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
 417
 418         /* register new adapter to i2c module... */
 419         adap->algo = &pcf_algo;
 420
 421         if ((rval = pcf_init_8584(pcf_adap)))
 422                 return rval;
 423
 424         rval = i2c_add_adapter(adap);
 425
 426         return rval;
 427 }
 428 EXPORT_SYMBOL(i2c_pcf_add_bus);
 429
 430 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
 431 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
 432 MODULE_LICENSE("GPL");
 433
 434 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
 435 MODULE_PARM_DESC(i2c_debug,
 436         "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");