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 = i2c_8bit_addr_from_msg(msg);
 116
 117         DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
 118              msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
 119
 120         pca_outw(adap, I2C_PCA_DAT, addr);
 121
 122         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 123         pca_set_con(adap, sta);
 124
 125         return pca_wait(adap);
 126 }
 127
 128 /*
 129  * Transmit a byte.
 130  *
 131  * Returns after the byte has been transmitted
 132  */
 133 static int pca_tx_byte(struct i2c_algo_pca_data *adap,
 134                        __u8 b)
 135 {
 136         int sta = pca_get_con(adap);
 137         DEB2("=== WRITE %#04x\n", b);
 138         pca_outw(adap, I2C_PCA_DAT, b);
 139
 140         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 141         pca_set_con(adap, sta);
 142
 143         return pca_wait(adap);
 144 }
 145
 146 /*
 147  * Receive a byte
 148  *
 149  * returns immediately.
 150  */
 151 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
 152                         __u8 *b, int ack)
 153 {
 154         *b = pca_inw(adap, I2C_PCA_DAT);
 155         DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
 156 }
 157
 158 /*
 159  * Setup ACK or NACK for next received byte and wait for it to arrive.
 160  *
 161  * Returns after next byte has arrived.
 162  */
 163 static int pca_rx_ack(struct i2c_algo_pca_data *adap,
 164                       int ack)
 165 {
 166         int sta = pca_get_con(adap);
 167
 168         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
 169
 170         if (ack)
 171                 sta |= I2C_PCA_CON_AA;
 172
 173         pca_set_con(adap, sta);
 174         return pca_wait(adap);
 175 }
 176
 177 static int pca_xfer(struct i2c_adapter *i2c_adap,
 178                     struct i2c_msg *msgs,
 179                     int num)
 180 {
 181         struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
 182         struct i2c_msg *msg = NULL;
 183         int curmsg;
 184         int numbytes = 0;
 185         int state;
 186         int ret;
 187         int completed = 1;
 188         unsigned long timeout = jiffies + i2c_adap->timeout;
 189
 190         while ((state = pca_status(adap)) != 0xf8) {
 191                 if (time_before(jiffies, timeout)) {
 192                         msleep(10);
 193                 } else {
 194                         dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
 195                                 "%#04x\n", state);
 196                         return -EBUSY;
 197                 }
 198         }
 199
 200         DEB1("{{{ XFER %d messages\n", num);
 201
 202         if (i2c_debug >= 2) {
 203                 for (curmsg = 0; curmsg < num; curmsg++) {
 204                         int addr, i;
 205                         msg = &msgs[curmsg];
 206
 207                         addr = (0x7f & msg->addr) ;
 208
 209                         if (msg->flags & I2C_M_RD)
 210                                 printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
 211                                        curmsg, msg->len, addr, (addr << 1) | 1);
 212                         else {
 213                                 printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
 214                                        curmsg, msg->len, addr, addr << 1,
 215                                        msg->len == 0 ? "" : ", ");
 216                                 for (i = 0; i < msg->len; i++)
 217                                         printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
 218                                 printk("]\n");
 219                         }
 220                 }
 221         }
 222
 223         curmsg = 0;
 224         ret = -EIO;
 225         while (curmsg < num) {
 226                 state = pca_status(adap);
 227
 228                 DEB3("STATE is 0x%02x\n", state);
 229                 msg = &msgs[curmsg];
 230
 231                 switch (state) {
 232                 case 0xf8: /* On reset or stop the bus is idle */
 233                         completed = pca_start(adap);
 234                         break;
 235
 236                 case 0x08: /* A START condition has been transmitted */
 237                 case 0x10: /* A repeated start condition has been transmitted */
 238                         completed = pca_address(adap, msg);
 239                         break;
 240
 241                 case 0x18: /* SLA+W has been transmitted; ACK has been received */
 242                 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
 243                         if (numbytes < msg->len) {
 244                                 completed = pca_tx_byte(adap,
 245                                                         msg->buf[numbytes]);
 246                                 numbytes++;
 247                                 break;
 248                         }
 249                         curmsg++; numbytes = 0;
 250                         if (curmsg == num)
 251                                 pca_stop(adap);
 252                         else
 253                                 completed = pca_repeated_start(adap);
 254                         break;
 255
 256                 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
 257                         DEB2("NOT ACK received after SLA+W\n");
 258                         pca_stop(adap);
 259                         ret = -ENXIO;
 260                         goto out;
 261
 262                 case 0x40: /* SLA+R has been transmitted; ACK has been received */
 263                         completed = pca_rx_ack(adap, msg->len > 1);
 264                         break;
 265
 266                 case 0x50: /* Data bytes has been received; ACK has been returned */
 267                         if (numbytes < msg->len) {
 268                                 pca_rx_byte(adap, &msg->buf[numbytes], 1);
 269                                 numbytes++;
 270                                 completed = pca_rx_ack(adap,
 271                                                        numbytes < msg->len - 1);
 272                                 break;
 273                         }
 274                         curmsg++; numbytes = 0;
 275                         if (curmsg == num)
 276                                 pca_stop(adap);
 277                         else
 278                                 completed = pca_repeated_start(adap);
 279                         break;
 280
 281                 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
 282                         DEB2("NOT ACK received after SLA+R\n");
 283                         pca_stop(adap);
 284                         ret = -ENXIO;
 285                         goto out;
 286
 287                 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
 288                         DEB2("NOT ACK received after data byte\n");
 289                         pca_stop(adap);
 290                         goto out;
 291
 292                 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
 293                         DEB2("Arbitration lost\n");
 294                         /*
 295                          * The PCA9564 data sheet (2006-09-01) says "A
 296                          * START condition will be transmitted when the
 297                          * bus becomes free (STOP or SCL and SDA high)"
 298                          * when the STA bit is set (p. 11).
 299                          *
 300                          * In case this won't work, try pca_reset()
 301                          * instead.
 302                          */
 303                         pca_start(adap);
 304                         goto out;
 305
 306                 case 0x58: /* Data byte has been received; NOT ACK has been returned */
 307                         if (numbytes == msg->len - 1) {
 308                                 pca_rx_byte(adap, &msg->buf[numbytes], 0);
 309                                 curmsg++; numbytes = 0;
 310                                 if (curmsg == num)
 311                                         pca_stop(adap);
 312                                 else
 313                                         completed = pca_repeated_start(adap);
 314                         } else {
 315                                 DEB2("NOT ACK sent after data byte received. "
 316                                      "Not final byte. numbytes %d. len %d\n",
 317                                      numbytes, msg->len);
 318                                 pca_stop(adap);
 319                                 goto out;
 320                         }
 321                         break;
 322                 case 0x70: /* Bus error - SDA stuck low */
 323                         DEB2("BUS ERROR - SDA Stuck low\n");
 324                         pca_reset(adap);
 325                         goto out;
 326                 case 0x90: /* Bus error - SCL stuck low */
 327                         DEB2("BUS ERROR - SCL Stuck low\n");
 328                         pca_reset(adap);
 329                         goto out;
 330                 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
 331                         DEB2("BUS ERROR - Illegal START or STOP\n");
 332                         pca_reset(adap);
 333                         goto out;
 334                 default:
 335                         dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
 336                         break;
 337                 }
 338
 339                 if (!completed)
 340                         goto out;
 341         }
 342
 343         ret = curmsg;
 344  out:
 345         DEB1("}}} transferred %d/%d messages. "
 346              "status is %#04x. control is %#04x\n",
 347              curmsg, num, pca_status(adap),
 348              pca_get_con(adap));
 349         return ret;
 350 }
 351
 352 static u32 pca_func(struct i2c_adapter *adap)
 353 {
 354         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 355 }
 356
 357 static const struct i2c_algorithm pca_algo = {
 358         .master_xfer    = pca_xfer,
 359         .functionality  = pca_func,
 360 };
 361
 362 static unsigned int pca_probe_chip(struct i2c_adapter *adap)
 363 {
 364         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 365         /* The trick here is to check if there is an indirect register
 366          * available. If there is one, we will read the value we first
 367          * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
 368          * we wrote on I2C_PCA_ADR
 369          */
 370         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 371         pca_outw(pca_data, I2C_PCA_IND, 0xAA);
 372         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
 373         pca_outw(pca_data, I2C_PCA_IND, 0x00);
 374         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 375         if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
 376                 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
 377                 pca_data->chip = I2C_PCA_CHIP_9665;
 378         } else {
 379                 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
 380                 pca_data->chip = I2C_PCA_CHIP_9564;
 381         }
 382         return pca_data->chip;
 383 }
 384
 385 static int pca_init(struct i2c_adapter *adap)
 386 {
 387         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 388
 389         adap->algo = &pca_algo;
 390
 391         if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
 392                 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
 393                 int clock;
 394
 395                 if (pca_data->i2c_clock > 7) {
 396                         switch (pca_data->i2c_clock) {
 397                         case 330000:
 398                                 pca_data->i2c_clock = I2C_PCA_CON_330kHz;
 399                                 break;
 400                         case 288000:
 401                                 pca_data->i2c_clock = I2C_PCA_CON_288kHz;
 402                                 break;
 403                         case 217000:
 404                                 pca_data->i2c_clock = I2C_PCA_CON_217kHz;
 405                                 break;
 406                         case 146000:
 407                                 pca_data->i2c_clock = I2C_PCA_CON_146kHz;
 408                                 break;
 409                         case 88000:
 410                                 pca_data->i2c_clock = I2C_PCA_CON_88kHz;
 411                                 break;
 412                         case 59000:
 413                                 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 414                                 break;
 415                         case 44000:
 416                                 pca_data->i2c_clock = I2C_PCA_CON_44kHz;
 417                                 break;
 418                         case 36000:
 419                                 pca_data->i2c_clock = I2C_PCA_CON_36kHz;
 420                                 break;
 421                         default:
 422                                 printk(KERN_WARNING
 423                                         "%s: Invalid I2C clock speed selected."
 424                                         " Using default 59kHz.\n", adap->name);
 425                         pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 426                         }
 427                 } else {
 428                         printk(KERN_WARNING "%s: "
 429                                 "Choosing the clock frequency based on "
 430                                 "index is deprecated."
 431                                 " Use the nominal frequency.\n", adap->name);
 432                 }
 433
 434                 pca_reset(pca_data);
 435
 436                 clock = pca_clock(pca_data);
 437                 printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
 438                      adap->name, freqs[clock]);
 439
 440                 pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock);
 441         } else {
 442                 int clock;
 443                 int mode;
 444                 int tlow, thi;
 445                 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */
 446                 int min_tlow, min_thi;
 447                 /* These values are the maximum raise and fall values allowed
 448                  * by the I2C operation mode (Standard, Fast or Fast+)
 449                  * They are used (added) below to calculate the clock dividers
 450                  * of PCA9665. Note that they are slightly different of the
 451                  * real maximum, to allow the change on mode exactly on the
 452                  * maximum clock rate for each mode
 453                  */
 454                 int raise_fall_time;
 455
 456                 if (pca_data->i2c_clock > 1265800) {
 457                         printk(KERN_WARNING "%s: I2C clock speed too high."
 458                                 " Using 1265.8kHz.\n", adap->name);
 459                         pca_data->i2c_clock = 1265800;
 460                 }
 461
 462                 if (pca_data->i2c_clock < 60300) {
 463                         printk(KERN_WARNING "%s: I2C clock speed too low."
 464                                 " Using 60.3kHz.\n", adap->name);
 465                         pca_data->i2c_clock = 60300;
 466                 }
 467
 468                 /* To avoid integer overflow, use clock/100 for calculations */
 469                 clock = pca_clock(pca_data) / 100;
 470
 471                 if (pca_data->i2c_clock > 1000000) {
 472                         mode = I2C_PCA_MODE_TURBO;
 473                         min_tlow = 14;
 474                         min_thi  = 5;
 475                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 476                 } else if (pca_data->i2c_clock > 400000) {
 477                         mode = I2C_PCA_MODE_FASTP;
 478                         min_tlow = 17;
 479                         min_thi  = 9;
 480                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 481                 } else if (pca_data->i2c_clock > 100000) {
 482                         mode = I2C_PCA_MODE_FAST;
 483                         min_tlow = 44;
 484                         min_thi  = 20;
 485                         raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
 486                 } else {
 487                         mode = I2C_PCA_MODE_STD;
 488                         min_tlow = 157;
 489                         min_thi  = 134;
 490                         raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
 491                 }
 492
 493                 /* The minimum clock that respects the thi/tlow = 134/157 is
 494                  * 64800 Hz. Below that, we have to fix the tlow to 255 and
 495                  * calculate the thi factor.
 496                  */
 497                 if (clock < 648) {
 498                         tlow = 255;
 499                         thi = 1000000 - clock * raise_fall_time;
 500                         thi /= (I2C_PCA_OSC_PER * clock) - tlow;
 501                 } else {
 502                         tlow = (1000000 - clock * raise_fall_time) * min_tlow;
 503                         tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
 504                         thi = tlow * min_thi / min_tlow;
 505                 }
 506
 507                 pca_reset(pca_data);
 508
 509                 printk(KERN_INFO
 510                      "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
 511
 512                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE);
 513                 pca_outw(pca_data, I2C_PCA_IND, mode);
 514                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
 515                 pca_outw(pca_data, I2C_PCA_IND, tlow);
 516                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
 517                 pca_outw(pca_data, I2C_PCA_IND, thi);
 518
 519                 pca_set_con(pca_data, I2C_PCA_CON_ENSIO);
 520         }
 521         udelay(500); /* 500 us for oscillator to stabilise */
 522
 523         return 0;
 524 }
 525
 526 /*
 527  * registering functions to load algorithms at runtime
 528  */
 529 int i2c_pca_add_bus(struct i2c_adapter *adap)
 530 {
 531         int rval;
 532
 533         rval = pca_init(adap);
 534         if (rval)
 535                 return rval;
 536
 537         return i2c_add_adapter(adap);
 538 }
 539 EXPORT_SYMBOL(i2c_pca_add_bus);
 540
 541 int i2c_pca_add_numbered_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_numbered_adapter(adap);
 550 }
 551 EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
 552
 553 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
 554         "Wolfram Sang <w.sang@pengutronix.de>");
 555 MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
 556 MODULE_LICENSE("GPL");
 557
 558 module_param(i2c_debug, int, 0);