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

   1 /*
   2  *  i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters
   3  *    Copyright (C) 2004 Arcom Control Systems
   4  *    Copyright (C) 2008 Pengutronix
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/delay.h>
  21 #include <linux/jiffies.h>
  22 #include <linux/errno.h>
  23 #include <linux/i2c.h>
  24 #include <linux/i2c-algo-pca.h>
  25
  26 #define DEB1(fmt, args...) do { if (i2c_debug >= 1)                     \
  27                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  28 #define DEB2(fmt, args...) do { if (i2c_debug >= 2)                     \
  29                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  30 #define DEB3(fmt, args...) do { if (i2c_debug >= 3)                     \
  31                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  32
  33 static int i2c_debug;
  34
  35 #define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val)
  36 #define pca_inw(adap, reg) adap->read_byte(adap->data, reg)
  37
  38 #define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
  39 #define pca_clock(adap) adap->i2c_clock
  40 #define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
  41 #define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
  42 #define pca_wait(adap) adap->wait_for_completion(adap->data)
  43
  44 static void pca_reset(struct i2c_algo_pca_data *adap)
  45 {
  46         if (adap->chip == I2C_PCA_CHIP_9665) {
  47                 /* Ignore the reset function from the module,
  48                  * we can use the parallel bus reset.
  49                  */
  50                 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET);
  51                 pca_outw(adap, I2C_PCA_IND, 0xA5);
  52                 pca_outw(adap, I2C_PCA_IND, 0x5A);
  53
  54                 /*
  55                  * After a reset we need to re-apply any configuration
  56                  * (calculated in pca_init) to get the bus in a working state.
  57                  */
  58                 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IMODE);
  59                 pca_outw(adap, I2C_PCA_IND, adap->bus_settings.mode);
  60                 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
  61                 pca_outw(adap, I2C_PCA_IND, adap->bus_settings.tlow);
  62                 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
  63                 pca_outw(adap, I2C_PCA_IND, adap->bus_settings.thi);
  64
  65                 pca_set_con(adap, I2C_PCA_CON_ENSIO);
  66         } else {
  67                 adap->reset_chip(adap->data);
  68                 pca_set_con(adap, I2C_PCA_CON_ENSIO | adap->bus_settings.clock_freq);
  69         }
  70 }
  71
  72 /*
  73  * Generate a start condition on the i2c bus.
  74  *
  75  * returns after the start condition has occurred
  76  */
  77 static int pca_start(struct i2c_algo_pca_data *adap)
  78 {
  79         int sta = pca_get_con(adap);
  80         DEB2("=== START\n");
  81         sta |= I2C_PCA_CON_STA;
  82         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  83         pca_set_con(adap, sta);
  84         return pca_wait(adap);
  85 }
  86
  87 /*
  88  * Generate a repeated start condition on the i2c bus
  89  *
  90  * return after the repeated start condition has occurred
  91  */
  92 static int pca_repeated_start(struct i2c_algo_pca_data *adap)
  93 {
  94         int sta = pca_get_con(adap);
  95         DEB2("=== REPEATED START\n");
  96         sta |= I2C_PCA_CON_STA;
  97         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  98         pca_set_con(adap, sta);
  99         return pca_wait(adap);
 100 }
 101
 102 /*
 103  * Generate a stop condition on the i2c bus
 104  *
 105  * returns after the stop condition has been generated
 106  *
 107  * STOPs do not generate an interrupt or set the SI flag, since the
 108  * part returns the idle state (0xf8). Hence we don't need to
 109  * pca_wait here.
 110  */
 111 static void pca_stop(struct i2c_algo_pca_data *adap)
 112 {
 113         int sta = pca_get_con(adap);
 114         DEB2("=== STOP\n");
 115         sta |= I2C_PCA_CON_STO;
 116         sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 117         pca_set_con(adap, sta);
 118 }
 119
 120 /*
 121  * Send the slave address and R/W bit
 122  *
 123  * returns after the address has been sent
 124  */
 125 static int pca_address(struct i2c_algo_pca_data *adap,
 126                        struct i2c_msg *msg)
 127 {
 128         int sta = pca_get_con(adap);
 129         int addr = i2c_8bit_addr_from_msg(msg);
 130
 131         DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
 132              msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
 133
 134         pca_outw(adap, I2C_PCA_DAT, addr);
 135
 136         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 137         pca_set_con(adap, sta);
 138
 139         return pca_wait(adap);
 140 }
 141
 142 /*
 143  * Transmit a byte.
 144  *
 145  * Returns after the byte has been transmitted
 146  */
 147 static int pca_tx_byte(struct i2c_algo_pca_data *adap,
 148                        __u8 b)
 149 {
 150         int sta = pca_get_con(adap);
 151         DEB2("=== WRITE %#04x\n", b);
 152         pca_outw(adap, I2C_PCA_DAT, b);
 153
 154         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 155         pca_set_con(adap, sta);
 156
 157         return pca_wait(adap);
 158 }
 159
 160 /*
 161  * Receive a byte
 162  *
 163  * returns immediately.
 164  */
 165 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
 166                         __u8 *b, int ack)
 167 {
 168         *b = pca_inw(adap, I2C_PCA_DAT);
 169         DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
 170 }
 171
 172 /*
 173  * Setup ACK or NACK for next received byte and wait for it to arrive.
 174  *
 175  * Returns after next byte has arrived.
 176  */
 177 static int pca_rx_ack(struct i2c_algo_pca_data *adap,
 178                       int ack)
 179 {
 180         int sta = pca_get_con(adap);
 181
 182         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
 183
 184         if (ack)
 185                 sta |= I2C_PCA_CON_AA;
 186
 187         pca_set_con(adap, sta);
 188         return pca_wait(adap);
 189 }
 190
 191 static int pca_xfer(struct i2c_adapter *i2c_adap,
 192                     struct i2c_msg *msgs,
 193                     int num)
 194 {
 195         struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
 196         struct i2c_msg *msg = NULL;
 197         int curmsg;
 198         int numbytes = 0;
 199         int state;
 200         int ret;
 201         int completed = 1;
 202         unsigned long timeout = jiffies + i2c_adap->timeout;
 203
 204         while ((state = pca_status(adap)) != 0xf8) {
 205                 if (time_before(jiffies, timeout)) {
 206                         msleep(10);
 207                 } else {
 208                         dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
 209                                 "%#04x\n", state);
 210                         return -EBUSY;
 211                 }
 212         }
 213
 214         DEB1("{{{ XFER %d messages\n", num);
 215
 216         if (i2c_debug >= 2) {
 217                 for (curmsg = 0; curmsg < num; curmsg++) {
 218                         int addr, i;
 219                         msg = &msgs[curmsg];
 220
 221                         addr = (0x7f & msg->addr) ;
 222
 223                         if (msg->flags & I2C_M_RD)
 224                                 printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
 225                                        curmsg, msg->len, addr, (addr << 1) | 1);
 226                         else {
 227                                 printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
 228                                        curmsg, msg->len, addr, addr << 1,
 229                                        msg->len == 0 ? "" : ", ");
 230                                 for (i = 0; i < msg->len; i++)
 231                                         printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
 232                                 printk("]\n");
 233                         }
 234                 }
 235         }
 236
 237         curmsg = 0;
 238         ret = -EIO;
 239         while (curmsg < num) {
 240                 state = pca_status(adap);
 241
 242                 DEB3("STATE is 0x%02x\n", state);
 243                 msg = &msgs[curmsg];
 244
 245                 switch (state) {
 246                 case 0xf8: /* On reset or stop the bus is idle */
 247                         completed = pca_start(adap);
 248                         break;
 249
 250                 case 0x08: /* A START condition has been transmitted */
 251                 case 0x10: /* A repeated start condition has been transmitted */
 252                         completed = pca_address(adap, msg);
 253                         break;
 254
 255                 case 0x18: /* SLA+W has been transmitted; ACK has been received */
 256                 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
 257                         if (numbytes < msg->len) {
 258                                 completed = pca_tx_byte(adap,
 259                                                         msg->buf[numbytes]);
 260                                 numbytes++;
 261                                 break;
 262                         }
 263                         curmsg++; numbytes = 0;
 264                         if (curmsg == num)
 265                                 pca_stop(adap);
 266                         else
 267                                 completed = pca_repeated_start(adap);
 268                         break;
 269
 270                 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
 271                         DEB2("NOT ACK received after SLA+W\n");
 272                         pca_stop(adap);
 273                         ret = -ENXIO;
 274                         goto out;
 275
 276                 case 0x40: /* SLA+R has been transmitted; ACK has been received */
 277                         completed = pca_rx_ack(adap, msg->len > 1);
 278                         break;
 279
 280                 case 0x50: /* Data bytes has been received; ACK has been returned */
 281                         if (numbytes < msg->len) {
 282                                 pca_rx_byte(adap, &msg->buf[numbytes], 1);
 283                                 numbytes++;
 284                                 completed = pca_rx_ack(adap,
 285                                                        numbytes < msg->len - 1);
 286                                 break;
 287                         }
 288                         curmsg++; numbytes = 0;
 289                         if (curmsg == num)
 290                                 pca_stop(adap);
 291                         else
 292                                 completed = pca_repeated_start(adap);
 293                         break;
 294
 295                 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
 296                         DEB2("NOT ACK received after SLA+R\n");
 297                         pca_stop(adap);
 298                         ret = -ENXIO;
 299                         goto out;
 300
 301                 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
 302                         DEB2("NOT ACK received after data byte\n");
 303                         pca_stop(adap);
 304                         goto out;
 305
 306                 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
 307                         DEB2("Arbitration lost\n");
 308                         /*
 309                          * The PCA9564 data sheet (2006-09-01) says "A
 310                          * START condition will be transmitted when the
 311                          * bus becomes free (STOP or SCL and SDA high)"
 312                          * when the STA bit is set (p. 11).
 313                          *
 314                          * In case this won't work, try pca_reset()
 315                          * instead.
 316                          */
 317                         pca_start(adap);
 318                         goto out;
 319
 320                 case 0x58: /* Data byte has been received; NOT ACK has been returned */
 321                         if (numbytes == msg->len - 1) {
 322                                 pca_rx_byte(adap, &msg->buf[numbytes], 0);
 323                                 curmsg++; numbytes = 0;
 324                                 if (curmsg == num)
 325                                         pca_stop(adap);
 326                                 else
 327                                         completed = pca_repeated_start(adap);
 328                         } else {
 329                                 DEB2("NOT ACK sent after data byte received. "
 330                                      "Not final byte. numbytes %d. len %d\n",
 331                                      numbytes, msg->len);
 332                                 pca_stop(adap);
 333                                 goto out;
 334                         }
 335                         break;
 336                 case 0x70: /* Bus error - SDA stuck low */
 337                         DEB2("BUS ERROR - SDA Stuck low\n");
 338                         pca_reset(adap);
 339                         goto out;
 340                 case 0x78: /* Bus error - SCL stuck low (PCA9665) */
 341                 case 0x90: /* Bus error - SCL stuck low (PCA9564) */
 342                         DEB2("BUS ERROR - SCL Stuck low\n");
 343                         pca_reset(adap);
 344                         goto out;
 345                 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
 346                         DEB2("BUS ERROR - Illegal START or STOP\n");
 347                         pca_reset(adap);
 348                         goto out;
 349                 default:
 350                         dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
 351                         break;
 352                 }
 353
 354                 if (!completed)
 355                         goto out;
 356         }
 357
 358         ret = curmsg;
 359  out:
 360         DEB1("}}} transferred %d/%d messages. "
 361              "status is %#04x. control is %#04x\n",
 362              curmsg, num, pca_status(adap),
 363              pca_get_con(adap));
 364         return ret;
 365 }
 366
 367 static u32 pca_func(struct i2c_adapter *adap)
 368 {
 369         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 370 }
 371
 372 static const struct i2c_algorithm pca_algo = {
 373         .master_xfer    = pca_xfer,
 374         .functionality  = pca_func,
 375 };
 376
 377 static unsigned int pca_probe_chip(struct i2c_adapter *adap)
 378 {
 379         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 380         /* The trick here is to check if there is an indirect register
 381          * available. If there is one, we will read the value we first
 382          * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
 383          * we wrote on I2C_PCA_ADR
 384          */
 385         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 386         pca_outw(pca_data, I2C_PCA_IND, 0xAA);
 387         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
 388         pca_outw(pca_data, I2C_PCA_IND, 0x00);
 389         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 390         if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
 391                 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
 392                 pca_data->chip = I2C_PCA_CHIP_9665;
 393         } else {
 394                 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
 395                 pca_data->chip = I2C_PCA_CHIP_9564;
 396         }
 397         return pca_data->chip;
 398 }
 399
 400 static int pca_init(struct i2c_adapter *adap)
 401 {
 402         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 403
 404         adap->algo = &pca_algo;
 405
 406         if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
 407                 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
 408                 int clock;
 409
 410                 if (pca_data->i2c_clock > 7) {
 411                         switch (pca_data->i2c_clock) {
 412                         case 330000:
 413                                 pca_data->i2c_clock = I2C_PCA_CON_330kHz;
 414                                 break;
 415                         case 288000:
 416                                 pca_data->i2c_clock = I2C_PCA_CON_288kHz;
 417                                 break;
 418                         case 217000:
 419                                 pca_data->i2c_clock = I2C_PCA_CON_217kHz;
 420                                 break;
 421                         case 146000:
 422                                 pca_data->i2c_clock = I2C_PCA_CON_146kHz;
 423                                 break;
 424                         case 88000:
 425                                 pca_data->i2c_clock = I2C_PCA_CON_88kHz;
 426                                 break;
 427                         case 59000:
 428                                 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 429                                 break;
 430                         case 44000:
 431                                 pca_data->i2c_clock = I2C_PCA_CON_44kHz;
 432                                 break;
 433                         case 36000:
 434                                 pca_data->i2c_clock = I2C_PCA_CON_36kHz;
 435                                 break;
 436                         default:
 437                                 printk(KERN_WARNING
 438                                         "%s: Invalid I2C clock speed selected."
 439                                         " Using default 59kHz.\n", adap->name);
 440                         pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 441                         }
 442                 } else {
 443                         printk(KERN_WARNING "%s: "
 444                                 "Choosing the clock frequency based on "
 445                                 "index is deprecated."
 446                                 " Use the nominal frequency.\n", adap->name);
 447                 }
 448
 449                 clock = pca_clock(pca_data);
 450                 printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
 451                      adap->name, freqs[clock]);
 452
 453                 /* Store settings as these will be needed when the PCA chip is reset */
 454                 pca_data->bus_settings.clock_freq = clock;
 455
 456                 pca_reset(pca_data);
 457         } else {
 458                 int clock;
 459                 int mode;
 460                 int tlow, thi;
 461                 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */
 462                 int min_tlow, min_thi;
 463                 /* These values are the maximum raise and fall values allowed
 464                  * by the I2C operation mode (Standard, Fast or Fast+)
 465                  * They are used (added) below to calculate the clock dividers
 466                  * of PCA9665. Note that they are slightly different of the
 467                  * real maximum, to allow the change on mode exactly on the
 468                  * maximum clock rate for each mode
 469                  */
 470                 int raise_fall_time;
 471
 472                 if (pca_data->i2c_clock > 1265800) {
 473                         printk(KERN_WARNING "%s: I2C clock speed too high."
 474                                 " Using 1265.8kHz.\n", adap->name);
 475                         pca_data->i2c_clock = 1265800;
 476                 }
 477
 478                 if (pca_data->i2c_clock < 60300) {
 479                         printk(KERN_WARNING "%s: I2C clock speed too low."
 480                                 " Using 60.3kHz.\n", adap->name);
 481                         pca_data->i2c_clock = 60300;
 482                 }
 483
 484                 /* To avoid integer overflow, use clock/100 for calculations */
 485                 clock = pca_clock(pca_data) / 100;
 486
 487                 if (pca_data->i2c_clock > 1000000) {
 488                         mode = I2C_PCA_MODE_TURBO;
 489                         min_tlow = 14;
 490                         min_thi  = 5;
 491                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 492                 } else if (pca_data->i2c_clock > 400000) {
 493                         mode = I2C_PCA_MODE_FASTP;
 494                         min_tlow = 17;
 495                         min_thi  = 9;
 496                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 497                 } else if (pca_data->i2c_clock > 100000) {
 498                         mode = I2C_PCA_MODE_FAST;
 499                         min_tlow = 44;
 500                         min_thi  = 20;
 501                         raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
 502                 } else {
 503                         mode = I2C_PCA_MODE_STD;
 504                         min_tlow = 157;
 505                         min_thi  = 134;
 506                         raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
 507                 }
 508
 509                 /* The minimum clock that respects the thi/tlow = 134/157 is
 510                  * 64800 Hz. Below that, we have to fix the tlow to 255 and
 511                  * calculate the thi factor.
 512                  */
 513                 if (clock < 648) {
 514                         tlow = 255;
 515                         thi = 1000000 - clock * raise_fall_time;
 516                         thi /= (I2C_PCA_OSC_PER * clock) - tlow;
 517                 } else {
 518                         tlow = (1000000 - clock * raise_fall_time) * min_tlow;
 519                         tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
 520                         thi = tlow * min_thi / min_tlow;
 521                 }
 522
 523                 /* Store settings as these will be needed when the PCA chip is reset */
 524                 pca_data->bus_settings.mode = mode;
 525                 pca_data->bus_settings.tlow = tlow;
 526                 pca_data->bus_settings.thi = thi;
 527
 528                 pca_reset(pca_data);
 529
 530                 printk(KERN_INFO
 531                      "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
 532         }
 533         udelay(500); /* 500 us for oscillator to stabilise */
 534
 535         return 0;
 536 }
 537
 538 /*
 539  * registering functions to load algorithms at runtime
 540  */
 541 int i2c_pca_add_bus(struct i2c_adapter *adap)
 542 {
 543         int rval;
 544
 545         rval = pca_init(adap);
 546         if (rval)
 547                 return rval;
 548
 549         return i2c_add_adapter(adap);
 550 }
 551 EXPORT_SYMBOL(i2c_pca_add_bus);
 552
 553 int i2c_pca_add_numbered_bus(struct i2c_adapter *adap)
 554 {
 555         int rval;
 556
 557         rval = pca_init(adap);
 558         if (rval)
 559                 return rval;
 560
 561         return i2c_add_numbered_adapter(adap);
 562 }
 563 EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
 564
 565 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
 566         "Wolfram Sang <w.sang@pengutronix.de>");
 567 MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
 568 MODULE_LICENSE("GPL");
 569
 570 module_param(i2c_debug, int, 0);