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

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters
   4  *    Copyright (C) 2004 Arcom Control Systems
   5  *    Copyright (C) 2008 Pengutronix
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/moduleparam.h>
  11 #include <linux/delay.h>
  12 #include <linux/jiffies.h>
  13 #include <linux/errno.h>
  14 #include <linux/i2c.h>
  15 #include <linux/i2c-algo-pca.h>
  16
  17 #define DEB1(fmt, args...) do { if (i2c_debug >= 1)                     \
  18                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  19 #define DEB2(fmt, args...) do { if (i2c_debug >= 2)                     \
  20                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  21 #define DEB3(fmt, args...) do { if (i2c_debug >= 3)                     \
  22                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  23
  24 static int i2c_debug;
  25
  26 #define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val)
  27 #define pca_inw(adap, reg) adap->read_byte(adap->data, reg)
  28
  29 #define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
  30 #define pca_clock(adap) adap->i2c_clock
  31 #define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
  32 #define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
  33 #define pca_wait(adap) adap->wait_for_completion(adap->data)
  34
  35 static void pca_reset(struct i2c_algo_pca_data *adap)
  36 {
  37         if (adap->chip == I2C_PCA_CHIP_9665) {
  38                 /* Ignore the reset function from the module,
  39                  * we can use the parallel bus reset.
  40                  */
  41                 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET);
  42                 pca_outw(adap, I2C_PCA_IND, 0xA5);
  43                 pca_outw(adap, I2C_PCA_IND, 0x5A);
  44
  45                 /*
  46                  * After a reset we need to re-apply any configuration
  47                  * (calculated in pca_init) to get the bus in a working state.
  48                  */
  49                 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IMODE);
  50                 pca_outw(adap, I2C_PCA_IND, adap->bus_settings.mode);
  51                 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
  52                 pca_outw(adap, I2C_PCA_IND, adap->bus_settings.tlow);
  53                 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
  54                 pca_outw(adap, I2C_PCA_IND, adap->bus_settings.thi);
  55
  56                 pca_set_con(adap, I2C_PCA_CON_ENSIO);
  57         } else {
  58                 adap->reset_chip(adap->data);
  59                 pca_set_con(adap, I2C_PCA_CON_ENSIO | adap->bus_settings.clock_freq);
  60         }
  61 }
  62
  63 /*
  64  * Generate a start condition on the i2c bus.
  65  *
  66  * returns after the start condition has occurred
  67  */
  68 static int pca_start(struct i2c_algo_pca_data *adap)
  69 {
  70         int sta = pca_get_con(adap);
  71         DEB2("=== START\n");
  72         sta |= I2C_PCA_CON_STA;
  73         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  74         pca_set_con(adap, sta);
  75         return pca_wait(adap);
  76 }
  77
  78 /*
  79  * Generate a repeated start condition on the i2c bus
  80  *
  81  * return after the repeated start condition has occurred
  82  */
  83 static int pca_repeated_start(struct i2c_algo_pca_data *adap)
  84 {
  85         int sta = pca_get_con(adap);
  86         DEB2("=== REPEATED START\n");
  87         sta |= I2C_PCA_CON_STA;
  88         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  89         pca_set_con(adap, sta);
  90         return pca_wait(adap);
  91 }
  92
  93 /*
  94  * Generate a stop condition on the i2c bus
  95  *
  96  * returns after the stop condition has been generated
  97  *
  98  * STOPs do not generate an interrupt or set the SI flag, since the
  99  * part returns the idle state (0xf8). Hence we don't need to
 100  * pca_wait here.
 101  */
 102 static void pca_stop(struct i2c_algo_pca_data *adap)
 103 {
 104         int sta = pca_get_con(adap);
 105         DEB2("=== STOP\n");
 106         sta |= I2C_PCA_CON_STO;
 107         sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 108         pca_set_con(adap, sta);
 109 }
 110
 111 /*
 112  * Send the slave address and R/W bit
 113  *
 114  * returns after the address has been sent
 115  */
 116 static int pca_address(struct i2c_algo_pca_data *adap,
 117                        struct i2c_msg *msg)
 118 {
 119         int sta = pca_get_con(adap);
 120         int addr = i2c_8bit_addr_from_msg(msg);
 121
 122         DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
 123              msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
 124
 125         pca_outw(adap, I2C_PCA_DAT, addr);
 126
 127         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 128         pca_set_con(adap, sta);
 129
 130         return pca_wait(adap);
 131 }
 132
 133 /*
 134  * Transmit a byte.
 135  *
 136  * Returns after the byte has been transmitted
 137  */
 138 static int pca_tx_byte(struct i2c_algo_pca_data *adap,
 139                        __u8 b)
 140 {
 141         int sta = pca_get_con(adap);
 142         DEB2("=== WRITE %#04x\n", b);
 143         pca_outw(adap, I2C_PCA_DAT, b);
 144
 145         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 146         pca_set_con(adap, sta);
 147
 148         return pca_wait(adap);
 149 }
 150
 151 /*
 152  * Receive a byte
 153  *
 154  * returns immediately.
 155  */
 156 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
 157                         __u8 *b, int ack)
 158 {
 159         *b = pca_inw(adap, I2C_PCA_DAT);
 160         DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
 161 }
 162
 163 /*
 164  * Setup ACK or NACK for next received byte and wait for it to arrive.
 165  *
 166  * Returns after next byte has arrived.
 167  */
 168 static int pca_rx_ack(struct i2c_algo_pca_data *adap,
 169                       int ack)
 170 {
 171         int sta = pca_get_con(adap);
 172
 173         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
 174
 175         if (ack)
 176                 sta |= I2C_PCA_CON_AA;
 177
 178         pca_set_con(adap, sta);
 179         return pca_wait(adap);
 180 }
 181
 182 static int pca_xfer(struct i2c_adapter *i2c_adap,
 183                     struct i2c_msg *msgs,
 184                     int num)
 185 {
 186         struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
 187         struct i2c_msg *msg = NULL;
 188         int curmsg;
 189         int numbytes = 0;
 190         int state;
 191         int ret;
 192         int completed = 1;
 193         unsigned long timeout = jiffies + i2c_adap->timeout;
 194
 195         while ((state = pca_status(adap)) != 0xf8) {
 196                 if (time_before(jiffies, timeout)) {
 197                         msleep(10);
 198                 } else {
 199                         dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
 200                                 "%#04x\n", state);
 201                         return -EBUSY;
 202                 }
 203         }
 204
 205         DEB1("{{{ XFER %d messages\n", num);
 206
 207         if (i2c_debug >= 2) {
 208                 for (curmsg = 0; curmsg < num; curmsg++) {
 209                         int addr, i;
 210                         msg = &msgs[curmsg];
 211
 212                         addr = (0x7f & msg->addr) ;
 213
 214                         if (msg->flags & I2C_M_RD)
 215                                 printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
 216                                        curmsg, msg->len, addr, (addr << 1) | 1);
 217                         else {
 218                                 printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
 219                                        curmsg, msg->len, addr, addr << 1,
 220                                        msg->len == 0 ? "" : ", ");
 221                                 for (i = 0; i < msg->len; i++)
 222                                         printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
 223                                 printk("]\n");
 224                         }
 225                 }
 226         }
 227
 228         curmsg = 0;
 229         ret = -EIO;
 230         while (curmsg < num) {
 231                 state = pca_status(adap);
 232
 233                 DEB3("STATE is 0x%02x\n", state);
 234                 msg = &msgs[curmsg];
 235
 236                 switch (state) {
 237                 case 0xf8: /* On reset or stop the bus is idle */
 238                         completed = pca_start(adap);
 239                         break;
 240
 241                 case 0x08: /* A START condition has been transmitted */
 242                 case 0x10: /* A repeated start condition has been transmitted */
 243                         completed = pca_address(adap, msg);
 244                         break;
 245
 246                 case 0x18: /* SLA+W has been transmitted; ACK has been received */
 247                 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
 248                         if (numbytes < msg->len) {
 249                                 completed = pca_tx_byte(adap,
 250                                                         msg->buf[numbytes]);
 251                                 numbytes++;
 252                                 break;
 253                         }
 254                         curmsg++; numbytes = 0;
 255                         if (curmsg == num)
 256                                 pca_stop(adap);
 257                         else
 258                                 completed = pca_repeated_start(adap);
 259                         break;
 260
 261                 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
 262                         DEB2("NOT ACK received after SLA+W\n");
 263                         pca_stop(adap);
 264                         ret = -ENXIO;
 265                         goto out;
 266
 267                 case 0x40: /* SLA+R has been transmitted; ACK has been received */
 268                         completed = pca_rx_ack(adap, msg->len > 1);
 269                         break;
 270
 271                 case 0x50: /* Data bytes has been received; ACK has been returned */
 272                         if (numbytes < msg->len) {
 273                                 pca_rx_byte(adap, &msg->buf[numbytes], 1);
 274                                 numbytes++;
 275                                 completed = pca_rx_ack(adap,
 276                                                        numbytes < msg->len - 1);
 277                                 break;
 278                         }
 279                         curmsg++; numbytes = 0;
 280                         if (curmsg == num)
 281                                 pca_stop(adap);
 282                         else
 283                                 completed = pca_repeated_start(adap);
 284                         break;
 285
 286                 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
 287                         DEB2("NOT ACK received after SLA+R\n");
 288                         pca_stop(adap);
 289                         ret = -ENXIO;
 290                         goto out;
 291
 292                 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
 293                         DEB2("NOT ACK received after data byte\n");
 294                         pca_stop(adap);
 295                         goto out;
 296
 297                 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
 298                         DEB2("Arbitration lost\n");
 299                         /*
 300                          * The PCA9564 data sheet (2006-09-01) says "A
 301                          * START condition will be transmitted when the
 302                          * bus becomes free (STOP or SCL and SDA high)"
 303                          * when the STA bit is set (p. 11).
 304                          *
 305                          * In case this won't work, try pca_reset()
 306                          * instead.
 307                          */
 308                         pca_start(adap);
 309                         goto out;
 310
 311                 case 0x58: /* Data byte has been received; NOT ACK has been returned */
 312                         if (numbytes == msg->len - 1) {
 313                                 pca_rx_byte(adap, &msg->buf[numbytes], 0);
 314                                 curmsg++; numbytes = 0;
 315                                 if (curmsg == num)
 316                                         pca_stop(adap);
 317                                 else
 318                                         completed = pca_repeated_start(adap);
 319                         } else {
 320                                 DEB2("NOT ACK sent after data byte received. "
 321                                      "Not final byte. numbytes %d. len %d\n",
 322                                      numbytes, msg->len);
 323                                 pca_stop(adap);
 324                                 goto out;
 325                         }
 326                         break;
 327                 case 0x70: /* Bus error - SDA stuck low */
 328                         DEB2("BUS ERROR - SDA Stuck low\n");
 329                         pca_reset(adap);
 330                         goto out;
 331                 case 0x78: /* Bus error - SCL stuck low (PCA9665) */
 332                 case 0x90: /* Bus error - SCL stuck low (PCA9564) */
 333                         DEB2("BUS ERROR - SCL Stuck low\n");
 334                         pca_reset(adap);
 335                         goto out;
 336                 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
 337                         DEB2("BUS ERROR - Illegal START or STOP\n");
 338                         pca_reset(adap);
 339                         goto out;
 340                 default:
 341                         dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
 342                         break;
 343                 }
 344
 345                 if (!completed)
 346                         goto out;
 347         }
 348
 349         ret = curmsg;
 350  out:
 351         DEB1("}}} transferred %d/%d messages. "
 352              "status is %#04x. control is %#04x\n",
 353              curmsg, num, pca_status(adap),
 354              pca_get_con(adap));
 355         return ret;
 356 }
 357
 358 static u32 pca_func(struct i2c_adapter *adap)
 359 {
 360         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 361 }
 362
 363 static const struct i2c_algorithm pca_algo = {
 364         .master_xfer    = pca_xfer,
 365         .functionality  = pca_func,
 366 };
 367
 368 static unsigned int pca_probe_chip(struct i2c_adapter *adap)
 369 {
 370         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 371         /* The trick here is to check if there is an indirect register
 372          * available. If there is one, we will read the value we first
 373          * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
 374          * we wrote on I2C_PCA_ADR
 375          */
 376         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 377         pca_outw(pca_data, I2C_PCA_IND, 0xAA);
 378         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
 379         pca_outw(pca_data, I2C_PCA_IND, 0x00);
 380         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 381         if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
 382                 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
 383                 pca_data->chip = I2C_PCA_CHIP_9665;
 384         } else {
 385                 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
 386                 pca_data->chip = I2C_PCA_CHIP_9564;
 387         }
 388         return pca_data->chip;
 389 }
 390
 391 static int pca_init(struct i2c_adapter *adap)
 392 {
 393         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 394
 395         adap->algo = &pca_algo;
 396
 397         if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
 398                 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
 399                 int clock;
 400
 401                 if (pca_data->i2c_clock > 7) {
 402                         switch (pca_data->i2c_clock) {
 403                         case 330000:
 404                                 pca_data->i2c_clock = I2C_PCA_CON_330kHz;
 405                                 break;
 406                         case 288000:
 407                                 pca_data->i2c_clock = I2C_PCA_CON_288kHz;
 408                                 break;
 409                         case 217000:
 410                                 pca_data->i2c_clock = I2C_PCA_CON_217kHz;
 411                                 break;
 412                         case 146000:
 413                                 pca_data->i2c_clock = I2C_PCA_CON_146kHz;
 414                                 break;
 415                         case 88000:
 416                                 pca_data->i2c_clock = I2C_PCA_CON_88kHz;
 417                                 break;
 418                         case 59000:
 419                                 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 420                                 break;
 421                         case 44000:
 422                                 pca_data->i2c_clock = I2C_PCA_CON_44kHz;
 423                                 break;
 424                         case 36000:
 425                                 pca_data->i2c_clock = I2C_PCA_CON_36kHz;
 426                                 break;
 427                         default:
 428                                 printk(KERN_WARNING
 429                                         "%s: Invalid I2C clock speed selected."
 430                                         " Using default 59kHz.\n", adap->name);
 431                         pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 432                         }
 433                 } else {
 434                         printk(KERN_WARNING "%s: "
 435                                 "Choosing the clock frequency based on "
 436                                 "index is deprecated."
 437                                 " Use the nominal frequency.\n", adap->name);
 438                 }
 439
 440                 clock = pca_clock(pca_data);
 441                 printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
 442                      adap->name, freqs[clock]);
 443
 444                 /* Store settings as these will be needed when the PCA chip is reset */
 445                 pca_data->bus_settings.clock_freq = clock;
 446
 447                 pca_reset(pca_data);
 448         } else {
 449                 int clock;
 450                 int mode;
 451                 int tlow, thi;
 452                 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */
 453                 int min_tlow, min_thi;
 454                 /* These values are the maximum raise and fall values allowed
 455                  * by the I2C operation mode (Standard, Fast or Fast+)
 456                  * They are used (added) below to calculate the clock dividers
 457                  * of PCA9665. Note that they are slightly different of the
 458                  * real maximum, to allow the change on mode exactly on the
 459                  * maximum clock rate for each mode
 460                  */
 461                 int raise_fall_time;
 462
 463                 if (pca_data->i2c_clock > 1265800) {
 464                         printk(KERN_WARNING "%s: I2C clock speed too high."
 465                                 " Using 1265.8kHz.\n", adap->name);
 466                         pca_data->i2c_clock = 1265800;
 467                 }
 468
 469                 if (pca_data->i2c_clock < 60300) {
 470                         printk(KERN_WARNING "%s: I2C clock speed too low."
 471                                 " Using 60.3kHz.\n", adap->name);
 472                         pca_data->i2c_clock = 60300;
 473                 }
 474
 475                 /* To avoid integer overflow, use clock/100 for calculations */
 476                 clock = pca_clock(pca_data) / 100;
 477
 478                 if (pca_data->i2c_clock > I2C_MAX_FAST_MODE_PLUS_FREQ) {
 479                         mode = I2C_PCA_MODE_TURBO;
 480                         min_tlow = 14;
 481                         min_thi  = 5;
 482                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 483                 } else if (pca_data->i2c_clock > I2C_MAX_FAST_MODE_FREQ) {
 484                         mode = I2C_PCA_MODE_FASTP;
 485                         min_tlow = 17;
 486                         min_thi  = 9;
 487                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 488                 } else if (pca_data->i2c_clock > I2C_MAX_STANDARD_MODE_FREQ) {
 489                         mode = I2C_PCA_MODE_FAST;
 490                         min_tlow = 44;
 491                         min_thi  = 20;
 492                         raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
 493                 } else {
 494                         mode = I2C_PCA_MODE_STD;
 495                         min_tlow = 157;
 496                         min_thi  = 134;
 497                         raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
 498                 }
 499
 500                 /* The minimum clock that respects the thi/tlow = 134/157 is
 501                  * 64800 Hz. Below that, we have to fix the tlow to 255 and
 502                  * calculate the thi factor.
 503                  */
 504                 if (clock < 648) {
 505                         tlow = 255;
 506                         thi = 1000000 - clock * raise_fall_time;
 507                         thi /= (I2C_PCA_OSC_PER * clock) - tlow;
 508                 } else {
 509                         tlow = (1000000 - clock * raise_fall_time) * min_tlow;
 510                         tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
 511                         thi = tlow * min_thi / min_tlow;
 512                 }
 513
 514                 /* Store settings as these will be needed when the PCA chip is reset */
 515                 pca_data->bus_settings.mode = mode;
 516                 pca_data->bus_settings.tlow = tlow;
 517                 pca_data->bus_settings.thi = thi;
 518
 519                 pca_reset(pca_data);
 520
 521                 printk(KERN_INFO
 522                      "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
 523         }
 524         udelay(500); /* 500 us for oscillator 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 MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");
 558 MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
 559 MODULE_LICENSE("GPL");
 560
 561 module_param(i2c_debug, int, 0);