drivers/i2c/algos/i2c-algo-pcf.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters
   4  *
   5  *   Copyright (C) 1995-1997 Simon G. Vogl
   6  *                 1998-2000 Hans Berglund
   7  *
   8  * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
   9  * Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey
  10  * <mbailey@littlefeet-inc.com>
  11  *
  12  * Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
  13  * messages, proper stop/repstart signaling during receive, added detect code
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/delay.h>
  19 #include <linux/errno.h>
  20 #include <linux/i2c.h>
  21 #include <linux/i2c-algo-pcf.h>
  22 #include "i2c-algo-pcf.h"
  23
  24
  25 #define DEB2(x) if (i2c_debug >= 2) x
  26 #define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */
  27 #define DEBPROTO(x) if (i2c_debug >= 9) x;
  28         /* debug the protocol by showing transferred bits */
  29 #define DEF_TIMEOUT 16
  30
  31 /*
  32  * module parameters:
  33  */
  34 static int i2c_debug;
  35
  36 /* setting states on the bus with the right timing: */
  37
  38 #define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
  39 #define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
  40 #define get_own(adap) adap->getown(adap->data)
  41 #define get_clock(adap) adap->getclock(adap->data)
  42 #define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
  43 #define i2c_inb(adap) adap->getpcf(adap->data, 0)
  44
  45 /* other auxiliary functions */
  46
  47 static void i2c_start(struct i2c_algo_pcf_data *adap)
  48 {
  49         DEBPROTO(printk(KERN_DEBUG "S "));
  50         set_pcf(adap, 1, I2C_PCF_START);
  51 }
  52
  53 static void i2c_repstart(struct i2c_algo_pcf_data *adap)
  54 {
  55         DEBPROTO(printk(" Sr "));
  56         set_pcf(adap, 1, I2C_PCF_REPSTART);
  57 }
  58
  59 static void i2c_stop(struct i2c_algo_pcf_data *adap)
  60 {
  61         DEBPROTO(printk("P\n"));
  62         set_pcf(adap, 1, I2C_PCF_STOP);
  63 }
  64
  65 static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
  66 {
  67         DEB2(printk(KERN_INFO
  68                 "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
  69                 *status));
  70         /*
  71          * Cleanup from LAB -- reset and enable ESO.
  72          * This resets the PCF8584; since we've lost the bus, no
  73          * further attempts should be made by callers to clean up
  74          * (no i2c_stop() etc.)
  75          */
  76         set_pcf(adap, 1, I2C_PCF_PIN);
  77         set_pcf(adap, 1, I2C_PCF_ESO);
  78         /*
  79          * We pause for a time period sufficient for any running
  80          * I2C transaction to complete -- the arbitration logic won't
  81          * work properly until the next START is seen.
  82          * It is assumed the bus driver or client has set a proper value.
  83          *
  84          * REVISIT: should probably use msleep instead of mdelay if we
  85          * know we can sleep.
  86          */
  87         if (adap->lab_mdelay)
  88                 mdelay(adap->lab_mdelay);
  89
  90         DEB2(printk(KERN_INFO
  91                 "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
  92                 get_pcf(adap, 1)));
  93 }
  94
  95 static int wait_for_bb(struct i2c_algo_pcf_data *adap)
  96 {
  97
  98         int timeout = DEF_TIMEOUT;
  99         int status;
 100
 101         status = get_pcf(adap, 1);
 102
 103         while (!(status & I2C_PCF_BB) && --timeout) {
 104                 udelay(100); /* wait for 100 us */
 105                 status = get_pcf(adap, 1);
 106         }
 107
 108         if (timeout == 0) {
 109                 printk(KERN_ERR "Timeout waiting for Bus Busy\n");
 110                 return -ETIMEDOUT;
 111         }
 112
 113         return 0;
 114 }
 115
 116 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
 117 {
 118
 119         int timeout = DEF_TIMEOUT;
 120
 121         *status = get_pcf(adap, 1);
 122
 123         while ((*status & I2C_PCF_PIN) && --timeout) {
 124                 adap->waitforpin(adap->data);
 125                 *status = get_pcf(adap, 1);
 126         }
 127         if (*status & I2C_PCF_LAB) {
 128                 handle_lab(adap, status);
 129                 return -EINTR;
 130         }
 131
 132         if (timeout == 0)
 133                 return -ETIMEDOUT;
 134
 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",
 154                                 get_pcf(adap, 1)));
 155
 156         /* S1=0x80: S0 selected, serial interface off */
 157         set_pcf(adap, 1, I2C_PCF_PIN);
 158         /*
 159          * check to see S1 now used as R/W ctrl -
 160          * PCF8584 does that when ESO is zero
 161          */
 162         if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
 163                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
 164                 return -ENXIO; /* definitely not PCF8584 */
 165         }
 166
 167         /* load own address in S0, effective address is (own << 1) */
 168         i2c_outb(adap, get_own(adap));
 169         /* check it's really written */
 170         if ((temp = i2c_inb(adap)) != get_own(adap)) {
 171                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
 172                 return -ENXIO;
 173         }
 174
 175         /* S1=0xA0, next byte in S2 */
 176         set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
 177         /* check to see S2 now selected */
 178         if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
 179                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
 180                 return -ENXIO;
 181         }
 182
 183         /* load clock register S2 */
 184         i2c_outb(adap, get_clock(adap));
 185         /* check it's really written, the only 5 lowest bits does matter */
 186         if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
 187                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
 188                 return -ENXIO;
 189         }
 190
 191         /* Enable serial interface, idle, S0 selected */
 192         set_pcf(adap, 1, I2C_PCF_IDLE);
 193
 194         /* check to see PCF is really idled and we can access status register */
 195         if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
 196                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
 197                 return -ENXIO;
 198         }
 199
 200         printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");
 201
 202         return 0;
 203 }
 204
 205 static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
 206                          int count, int last)
 207 {
 208         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 209         int wrcount, status, timeout;
 210
 211         for (wrcount=0; wrcount<count; ++wrcount) {
 212                 DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
 213                                 buf[wrcount] & 0xff));
 214                 i2c_outb(adap, buf[wrcount]);
 215                 timeout = wait_for_pin(adap, &status);
 216                 if (timeout) {
 217                         if (timeout == -EINTR)
 218                                 return -EINTR; /* arbitration lost */
 219
 220                         i2c_stop(adap);
 221                         dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
 222                         return -EREMOTEIO; /* got a better one ?? */
 223                 }
 224                 if (status & I2C_PCF_LRB) {
 225                         i2c_stop(adap);
 226                         dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
 227                         return -EREMOTEIO; /* got a better one ?? */
 228                 }
 229         }
 230         if (last)
 231                 i2c_stop(adap);
 232         else
 233                 i2c_repstart(adap);
 234
 235         return wrcount;
 236 }
 237
 238 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
 239                          int count, int last)
 240 {
 241         int i, status;
 242         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 243         int wfp;
 244
 245         /* increment number of bytes to read by one -- read dummy byte */
 246         for (i = 0; i <= count; i++) {
 247
 248                 if ((wfp = wait_for_pin(adap, &status))) {
 249                         if (wfp == -EINTR)
 250                                 return -EINTR; /* arbitration lost */
 251
 252                         i2c_stop(adap);
 253                         dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
 254                         return -1;
 255                 }
 256
 257                 if ((status & I2C_PCF_LRB) && (i != count)) {
 258                         i2c_stop(adap);
 259                         dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
 260                         return -1;
 261                 }
 262
 263                 if (i == count - 1) {
 264                         set_pcf(adap, 1, I2C_PCF_ESO);
 265                 } else if (i == count) {
 266                         if (last)
 267                                 i2c_stop(adap);
 268                         else
 269                                 i2c_repstart(adap);
 270                 }
 271
 272                 if (i)
 273                         buf[i - 1] = i2c_inb(adap);
 274                 else
 275                         i2c_inb(adap); /* dummy read */
 276         }
 277
 278         return i - 1;
 279 }
 280
 281
 282 static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
 283                          struct i2c_msg *msg)
 284 {
 285         unsigned char addr = i2c_8bit_addr_from_msg(msg);
 286
 287         if (msg->flags & I2C_M_REV_DIR_ADDR)
 288                 addr ^= 1;
 289         i2c_outb(adap, addr);
 290
 291         return 0;
 292 }
 293
 294 static int pcf_xfer(struct i2c_adapter *i2c_adap,
 295                     struct i2c_msg *msgs,
 296                     int num)
 297 {
 298         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 299         struct i2c_msg *pmsg;
 300         int i;
 301         int ret=0, timeout, status;
 302
 303         if (adap->xfer_begin)
 304                 adap->xfer_begin(adap->data);
 305
 306         /* Check for bus busy */
 307         timeout = wait_for_bb(adap);
 308         if (timeout) {
 309                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
 310                             "Timeout waiting for BB in pcf_xfer\n");)
 311                 i = -EIO;
 312                 goto out;
 313         }
 314
 315         for (i = 0;ret >= 0 && i < num; i++) {
 316                 pmsg = &msgs[i];
 317
 318                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
 319                      pmsg->flags & I2C_M_RD ? "read" : "write",
 320                      pmsg->len, pmsg->addr, i + 1, num);)
 321
 322                 ret = pcf_doAddress(adap, pmsg);
 323
 324                 /* Send START */
 325                 if (i == 0)
 326                         i2c_start(adap);
 327
 328                 /* Wait for PIN (pending interrupt NOT) */
 329                 timeout = wait_for_pin(adap, &status);
 330                 if (timeout) {
 331                         if (timeout == -EINTR) {
 332                                 /* arbitration lost */
 333                                 i = -EINTR;
 334                                 goto out;
 335                         }
 336                         i2c_stop(adap);
 337                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
 338                                     "for PIN(1) in pcf_xfer\n");)
 339                         i = -EREMOTEIO;
 340                         goto out;
 341                 }
 342
 343                 /* Check LRB (last rcvd bit - slave ack) */
 344                 if (status & I2C_PCF_LRB) {
 345                         i2c_stop(adap);
 346                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
 347                         i = -EREMOTEIO;
 348                         goto out;
 349                 }
 350
 351                 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
 352                             i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
 353
 354                 if (pmsg->flags & I2C_M_RD) {
 355                         ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
 356                                             (i + 1 == num));
 357
 358                         if (ret != pmsg->len) {
 359                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 360                                             "only read %d bytes.\n",ret));
 361                         } else {
 362                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
 363                         }
 364                 } else {
 365                         ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
 366                                             (i + 1 == num));
 367
 368                         if (ret != pmsg->len) {
 369                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 370                                             "only wrote %d bytes.\n",ret));
 371                         } else {
 372                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
 373                         }
 374                 }
 375         }
 376
 377 out:
 378         if (adap->xfer_end)
 379                 adap->xfer_end(adap->data);
 380         return i;
 381 }
 382
 383 static u32 pcf_func(struct i2c_adapter *adap)
 384 {
 385         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 386                I2C_FUNC_PROTOCOL_MANGLING;
 387 }
 388
 389 /* exported algorithm data: */
 390 static const struct i2c_algorithm pcf_algo = {
 391         .master_xfer    = pcf_xfer,
 392         .functionality  = pcf_func,
 393 };
 394
 395 /*
 396  * registering functions to load algorithms at runtime
 397  */
 398 int i2c_pcf_add_bus(struct i2c_adapter *adap)
 399 {
 400         struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
 401         int rval;
 402
 403         DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
 404
 405         /* register new adapter to i2c module... */
 406         adap->algo = &pcf_algo;
 407
 408         if ((rval = pcf_init_8584(pcf_adap)))
 409                 return rval;
 410
 411         rval = i2c_add_adapter(adap);
 412
 413         return rval;
 414 }
 415 EXPORT_SYMBOL(i2c_pcf_add_bus);
 416
 417 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
 418 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
 419 MODULE_LICENSE("GPL");
 420
 421 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
 422 MODULE_PARM_DESC(i2c_debug,
 423         "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");