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  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  19  *  MA 02110-1301 USA.
  20  */
  21
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/moduleparam.h>
  25 #include <linux/delay.h>
  26 #include <linux/jiffies.h>
  27 #include <linux/init.h>
  28 #include <linux/errno.h>
  29 #include <linux/i2c.h>
  30 #include <linux/i2c-algo-pca.h>
  31
  32 #define DEB1(fmt, args...) do { if (i2c_debug >= 1)                     \
  33                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  34 #define DEB2(fmt, args...) do { if (i2c_debug >= 2)                     \
  35                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  36 #define DEB3(fmt, args...) do { if (i2c_debug >= 3)                     \
  37                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  38
  39 static int i2c_debug;
  40
  41 #define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val)
  42 #define pca_inw(adap, reg) adap->read_byte(adap->data, reg)
  43
  44 #define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
  45 #define pca_clock(adap) adap->i2c_clock
  46 #define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
  47 #define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
  48 #define pca_wait(adap) adap->wait_for_completion(adap->data)
  49
  50 static void pca_reset(struct i2c_algo_pca_data *adap)
  51 {
  52         if (adap->chip == I2C_PCA_CHIP_9665) {
  53                 /* Ignore the reset function from the module,
  54                  * we can use the parallel bus reset.
  55                  */
  56                 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET);
  57                 pca_outw(adap, I2C_PCA_IND, 0xA5);
  58                 pca_outw(adap, I2C_PCA_IND, 0x5A);
  59         } else {
  60                 adap->reset_chip(adap->data);
  61         }
  62 }
  63
  64 /*
  65  * Generate a start condition on the i2c bus.
  66  *
  67  * returns after the start condition has occurred
  68  */
  69 static int pca_start(struct i2c_algo_pca_data *adap)
  70 {
  71         int sta = pca_get_con(adap);
  72         DEB2("=== START\n");
  73         sta |= I2C_PCA_CON_STA;
  74         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  75         pca_set_con(adap, sta);
  76         return pca_wait(adap);
  77 }
  78
  79 /*
  80  * Generate a repeated start condition on the i2c bus
  81  *
  82  * return after the repeated start condition has occurred
  83  */
  84 static int pca_repeated_start(struct i2c_algo_pca_data *adap)
  85 {
  86         int sta = pca_get_con(adap);
  87         DEB2("=== REPEATED START\n");
  88         sta |= I2C_PCA_CON_STA;
  89         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  90         pca_set_con(adap, sta);
  91         return pca_wait(adap);
  92 }
  93
  94 /*
  95  * Generate a stop condition on the i2c bus
  96  *
  97  * returns after the stop condition has been generated
  98  *
  99  * STOPs do not generate an interrupt or set the SI flag, since the
 100  * part returns the idle state (0xf8). Hence we don't need to
 101  * pca_wait here.
 102  */
 103 static void pca_stop(struct i2c_algo_pca_data *adap)
 104 {
 105         int sta = pca_get_con(adap);
 106         DEB2("=== STOP\n");
 107         sta |= I2C_PCA_CON_STO;
 108         sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 109         pca_set_con(adap, sta);
 110 }
 111
 112 /*
 113  * Send the slave address and R/W bit
 114  *
 115  * returns after the address has been sent
 116  */
 117 static int pca_address(struct i2c_algo_pca_data *adap,
 118                        struct i2c_msg *msg)
 119 {
 120         int sta = pca_get_con(adap);
 121         int addr;
 122
 123         addr = ((0x7f & msg->addr) << 1);
 124         if (msg->flags & I2C_M_RD)
 125                 addr |= 1;
 126         DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
 127              msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
 128
 129         pca_outw(adap, I2C_PCA_DAT, addr);
 130
 131         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 132         pca_set_con(adap, sta);
 133
 134         return pca_wait(adap);
 135 }
 136
 137 /*
 138  * Transmit a byte.
 139  *
 140  * Returns after the byte has been transmitted
 141  */
 142 static int pca_tx_byte(struct i2c_algo_pca_data *adap,
 143                        __u8 b)
 144 {
 145         int sta = pca_get_con(adap);
 146         DEB2("=== WRITE %#04x\n", b);
 147         pca_outw(adap, I2C_PCA_DAT, b);
 148
 149         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 150         pca_set_con(adap, sta);
 151
 152         return pca_wait(adap);
 153 }
 154
 155 /*
 156  * Receive a byte
 157  *
 158  * returns immediately.
 159  */
 160 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
 161                         __u8 *b, int ack)
 162 {
 163         *b = pca_inw(adap, I2C_PCA_DAT);
 164         DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
 165 }
 166
 167 /*
 168  * Setup ACK or NACK for next received byte and wait for it to arrive.
 169  *
 170  * Returns after next byte has arrived.
 171  */
 172 static int pca_rx_ack(struct i2c_algo_pca_data *adap,
 173                       int ack)
 174 {
 175         int sta = pca_get_con(adap);
 176
 177         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
 178
 179         if (ack)
 180                 sta |= I2C_PCA_CON_AA;
 181
 182         pca_set_con(adap, sta);
 183         return pca_wait(adap);
 184 }
 185
 186 static int pca_xfer(struct i2c_adapter *i2c_adap,
 187                     struct i2c_msg *msgs,
 188                     int num)
 189 {
 190         struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
 191         struct i2c_msg *msg = NULL;
 192         int curmsg;
 193         int numbytes = 0;
 194         int state;
 195         int ret;
 196         int completed = 1;
 197         unsigned long timeout = jiffies + i2c_adap->timeout;
 198
 199         while ((state = pca_status(adap)) != 0xf8) {
 200                 if (time_before(jiffies, timeout)) {
 201                         msleep(10);
 202                 } else {
 203                         dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
 204                                 "%#04x\n", state);
 205                         return -EBUSY;
 206                 }
 207         }
 208
 209         DEB1("{{{ XFER %d messages\n", num);
 210
 211         if (i2c_debug >= 2) {
 212                 for (curmsg = 0; curmsg < num; curmsg++) {
 213                         int addr, i;
 214                         msg = &msgs[curmsg];
 215
 216                         addr = (0x7f & msg->addr) ;
 217
 218                         if (msg->flags & I2C_M_RD)
 219                                 printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
 220                                        curmsg, msg->len, addr, (addr << 1) | 1);
 221                         else {
 222                                 printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
 223                                        curmsg, msg->len, addr, addr << 1,
 224                                        msg->len == 0 ? "" : ", ");
 225                                 for (i = 0; i < msg->len; i++)
 226                                         printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
 227                                 printk("]\n");
 228                         }
 229                 }
 230         }
 231
 232         curmsg = 0;
 233         ret = -EIO;
 234         while (curmsg < num) {
 235                 state = pca_status(adap);
 236
 237                 DEB3("STATE is 0x%02x\n", state);
 238                 msg = &msgs[curmsg];
 239
 240                 switch (state) {
 241                 case 0xf8: /* On reset or stop the bus is idle */
 242                         completed = pca_start(adap);
 243                         break;
 244
 245                 case 0x08: /* A START condition has been transmitted */
 246                 case 0x10: /* A repeated start condition has been transmitted */
 247                         completed = pca_address(adap, msg);
 248                         break;
 249
 250                 case 0x18: /* SLA+W has been transmitted; ACK has been received */
 251                 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
 252                         if (numbytes < msg->len) {
 253                                 completed = pca_tx_byte(adap,
 254                                                         msg->buf[numbytes]);
 255                                 numbytes++;
 256                                 break;
 257                         }
 258                         curmsg++; numbytes = 0;
 259                         if (curmsg == num)
 260                                 pca_stop(adap);
 261                         else
 262                                 completed = pca_repeated_start(adap);
 263                         break;
 264
 265                 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
 266                         DEB2("NOT ACK received after SLA+W\n");
 267                         pca_stop(adap);
 268                         ret = -ENXIO;
 269                         goto out;
 270
 271                 case 0x40: /* SLA+R has been transmitted; ACK has been received */
 272                         completed = pca_rx_ack(adap, msg->len > 1);
 273                         break;
 274
 275                 case 0x50: /* Data bytes has been received; ACK has been returned */
 276                         if (numbytes < msg->len) {
 277                                 pca_rx_byte(adap, &msg->buf[numbytes], 1);
 278                                 numbytes++;
 279                                 completed = pca_rx_ack(adap,
 280                                                        numbytes < msg->len - 1);
 281                                 break;
 282                         }
 283                         curmsg++; numbytes = 0;
 284                         if (curmsg == num)
 285                                 pca_stop(adap);
 286                         else
 287                                 completed = pca_repeated_start(adap);
 288                         break;
 289
 290                 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
 291                         DEB2("NOT ACK received after SLA+R\n");
 292                         pca_stop(adap);
 293                         ret = -ENXIO;
 294                         goto out;
 295
 296                 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
 297                         DEB2("NOT ACK received after data byte\n");
 298                         pca_stop(adap);
 299                         goto out;
 300
 301                 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
 302                         DEB2("Arbitration lost\n");
 303                         /*
 304                          * The PCA9564 data sheet (2006-09-01) says "A
 305                          * START condition will be transmitted when the
 306                          * bus becomes free (STOP or SCL and SDA high)"
 307                          * when the STA bit is set (p. 11).
 308                          *
 309                          * In case this won't work, try pca_reset()
 310                          * instead.
 311                          */
 312                         pca_start(adap);
 313                         goto out;
 314
 315                 case 0x58: /* Data byte has been received; NOT ACK has been returned */
 316                         if (numbytes == msg->len - 1) {
 317                                 pca_rx_byte(adap, &msg->buf[numbytes], 0);
 318                                 curmsg++; numbytes = 0;
 319                                 if (curmsg == num)
 320                                         pca_stop(adap);
 321                                 else
 322                                         completed = pca_repeated_start(adap);
 323                         } else {
 324                                 DEB2("NOT ACK sent after data byte received. "
 325                                      "Not final byte. numbytes %d. len %d\n",
 326                                      numbytes, msg->len);
 327                                 pca_stop(adap);
 328                                 goto out;
 329                         }
 330                         break;
 331                 case 0x70: /* Bus error - SDA stuck low */
 332                         DEB2("BUS ERROR - SDA Stuck low\n");
 333                         pca_reset(adap);
 334                         goto out;
 335                 case 0x90: /* Bus error - SCL stuck low */
 336                         DEB2("BUS ERROR - SCL Stuck low\n");
 337                         pca_reset(adap);
 338                         goto out;
 339                 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
 340                         DEB2("BUS ERROR - Illegal START or STOP\n");
 341                         pca_reset(adap);
 342                         goto out;
 343                 default:
 344                         dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
 345                         break;
 346                 }
 347
 348                 if (!completed)
 349                         goto out;
 350         }
 351
 352         ret = curmsg;
 353  out:
 354         DEB1("}}} transferred %d/%d messages. "
 355              "status is %#04x. control is %#04x\n",
 356              curmsg, num, pca_status(adap),
 357              pca_get_con(adap));
 358         return ret;
 359 }
 360
 361 static u32 pca_func(struct i2c_adapter *adap)
 362 {
 363         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 364 }
 365
 366 static const struct i2c_algorithm pca_algo = {
 367         .master_xfer    = pca_xfer,
 368         .functionality  = pca_func,
 369 };
 370
 371 static unsigned int pca_probe_chip(struct i2c_adapter *adap)
 372 {
 373         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 374         /* The trick here is to check if there is an indirect register
 375          * available. If there is one, we will read the value we first
 376          * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
 377          * we wrote on I2C_PCA_ADR
 378          */
 379         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 380         pca_outw(pca_data, I2C_PCA_IND, 0xAA);
 381         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
 382         pca_outw(pca_data, I2C_PCA_IND, 0x00);
 383         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 384         if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
 385                 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
 386                 pca_data->chip = I2C_PCA_CHIP_9665;
 387         } else {
 388                 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
 389                 pca_data->chip = I2C_PCA_CHIP_9564;
 390         }
 391         return pca_data->chip;
 392 }
 393
 394 static int pca_init(struct i2c_adapter *adap)
 395 {
 396         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 397
 398         adap->algo = &pca_algo;
 399
 400         if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
 401                 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
 402                 int clock;
 403
 404                 if (pca_data->i2c_clock > 7) {
 405                         switch (pca_data->i2c_clock) {
 406                         case 330000:
 407                                 pca_data->i2c_clock = I2C_PCA_CON_330kHz;
 408                                 break;
 409                         case 288000:
 410                                 pca_data->i2c_clock = I2C_PCA_CON_288kHz;
 411                                 break;
 412                         case 217000:
 413                                 pca_data->i2c_clock = I2C_PCA_CON_217kHz;
 414                                 break;
 415                         case 146000:
 416                                 pca_data->i2c_clock = I2C_PCA_CON_146kHz;
 417                                 break;
 418                         case 88000:
 419                                 pca_data->i2c_clock = I2C_PCA_CON_88kHz;
 420                                 break;
 421                         case 59000:
 422                                 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 423                                 break;
 424                         case 44000:
 425                                 pca_data->i2c_clock = I2C_PCA_CON_44kHz;
 426                                 break;
 427                         case 36000:
 428                                 pca_data->i2c_clock = I2C_PCA_CON_36kHz;
 429                                 break;
 430                         default:
 431                                 printk(KERN_WARNING
 432                                         "%s: Invalid I2C clock speed selected."
 433                                         " Using default 59kHz.\n", adap->name);
 434                         pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 435                         }
 436                 } else {
 437                         printk(KERN_WARNING "%s: "
 438                                 "Choosing the clock frequency based on "
 439                                 "index is deprecated."
 440                                 " Use the nominal frequency.\n", adap->name);
 441                 }
 442
 443                 pca_reset(pca_data);
 444
 445                 clock = pca_clock(pca_data);
 446                 printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
 447                      adap->name, freqs[clock]);
 448
 449                 pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock);
 450         } else {
 451                 int clock;
 452                 int mode;
 453                 int tlow, thi;
 454                 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */
 455                 int min_tlow, min_thi;
 456                 /* These values are the maximum raise and fall values allowed
 457                  * by the I2C operation mode (Standard, Fast or Fast+)
 458                  * They are used (added) below to calculate the clock dividers
 459                  * of PCA9665. Note that they are slightly different of the
 460                  * real maximum, to allow the change on mode exactly on the
 461                  * maximum clock rate for each mode
 462                  */
 463                 int raise_fall_time;
 464
 465                 if (pca_data->i2c_clock > 1265800) {
 466                         printk(KERN_WARNING "%s: I2C clock speed too high."
 467                                 " Using 1265.8kHz.\n", adap->name);
 468                         pca_data->i2c_clock = 1265800;
 469                 }
 470
 471                 if (pca_data->i2c_clock < 60300) {
 472                         printk(KERN_WARNING "%s: I2C clock speed too low."
 473                                 " Using 60.3kHz.\n", adap->name);
 474                         pca_data->i2c_clock = 60300;
 475                 }
 476
 477                 /* To avoid integer overflow, use clock/100 for calculations */
 478                 clock = pca_clock(pca_data) / 100;
 479
 480                 if (pca_data->i2c_clock > 1000000) {
 481                         mode = I2C_PCA_MODE_TURBO;
 482                         min_tlow = 14;
 483                         min_thi  = 5;
 484                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 485                 } else if (pca_data->i2c_clock > 400000) {
 486                         mode = I2C_PCA_MODE_FASTP;
 487                         min_tlow = 17;
 488                         min_thi  = 9;
 489                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 490                 } else if (pca_data->i2c_clock > 100000) {
 491                         mode = I2C_PCA_MODE_FAST;
 492                         min_tlow = 44;
 493                         min_thi  = 20;
 494                         raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
 495                 } else {
 496                         mode = I2C_PCA_MODE_STD;
 497                         min_tlow = 157;
 498                         min_thi  = 134;
 499                         raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
 500                 }
 501
 502                 /* The minimum clock that respects the thi/tlow = 134/157 is
 503                  * 64800 Hz. Below that, we have to fix the tlow to 255 and
 504                  * calculate the thi factor.
 505                  */
 506                 if (clock < 648) {
 507                         tlow = 255;
 508                         thi = 1000000 - clock * raise_fall_time;
 509                         thi /= (I2C_PCA_OSC_PER * clock) - tlow;
 510                 } else {
 511                         tlow = (1000000 - clock * raise_fall_time) * min_tlow;
 512                         tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
 513                         thi = tlow * min_thi / min_tlow;
 514                 }
 515
 516                 pca_reset(pca_data);
 517
 518                 printk(KERN_INFO
 519                      "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
 520
 521                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE);
 522                 pca_outw(pca_data, I2C_PCA_IND, mode);
 523                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
 524                 pca_outw(pca_data, I2C_PCA_IND, tlow);
 525                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
 526                 pca_outw(pca_data, I2C_PCA_IND, thi);
 527
 528                 pca_set_con(pca_data, I2C_PCA_CON_ENSIO);
 529         }
 530         udelay(500); /* 500 us for oscilator to stabilise */
 531
 532         return 0;
 533 }
 534
 535 /*
 536  * registering functions to load algorithms at runtime
 537  */
 538 int i2c_pca_add_bus(struct i2c_adapter *adap)
 539 {
 540         int rval;
 541
 542         rval = pca_init(adap);
 543         if (rval)
 544                 return rval;
 545
 546         return i2c_add_adapter(adap);
 547 }
 548 EXPORT_SYMBOL(i2c_pca_add_bus);
 549
 550 int i2c_pca_add_numbered_bus(struct i2c_adapter *adap)
 551 {
 552         int rval;
 553
 554         rval = pca_init(adap);
 555         if (rval)
 556                 return rval;
 557
 558         return i2c_add_numbered_adapter(adap);
 559 }
 560 EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
 561
 562 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
 563         "Wolfram Sang <w.sang@pengutronix.de>");
 564 MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
 565 MODULE_LICENSE("GPL");
 566
 567 module_param(i2c_debug, int, 0);