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