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 #define pca_reset(adap) adap->reset_chip(adap->data)
  50
  51 static void pca9665_reset(void *pd)
  52 {
  53         struct i2c_algo_pca_data *adap = pd;
  54         pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET);
  55         pca_outw(adap, I2C_PCA_IND, 0xA5);
  56         pca_outw(adap, I2C_PCA_IND, 0x5A);
  57 }
  58
  59 /*
  60  * Generate a start condition on the i2c bus.
  61  *
  62  * returns after the start condition has occurred
  63  */
  64 static int pca_start(struct i2c_algo_pca_data *adap)
  65 {
  66         int sta = pca_get_con(adap);
  67         DEB2("=== START\n");
  68         sta |= I2C_PCA_CON_STA;
  69         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  70         pca_set_con(adap, sta);
  71         return pca_wait(adap);
  72 }
  73
  74 /*
  75  * Generate a repeated start condition on the i2c bus
  76  *
  77  * return after the repeated start condition has occurred
  78  */
  79 static int pca_repeated_start(struct i2c_algo_pca_data *adap)
  80 {
  81         int sta = pca_get_con(adap);
  82         DEB2("=== REPEATED START\n");
  83         sta |= I2C_PCA_CON_STA;
  84         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  85         pca_set_con(adap, sta);
  86         return pca_wait(adap);
  87 }
  88
  89 /*
  90  * Generate a stop condition on the i2c bus
  91  *
  92  * returns after the stop condition has been generated
  93  *
  94  * STOPs do not generate an interrupt or set the SI flag, since the
  95  * part returns the idle state (0xf8). Hence we don't need to
  96  * pca_wait here.
  97  */
  98 static void pca_stop(struct i2c_algo_pca_data *adap)
  99 {
 100         int sta = pca_get_con(adap);
 101         DEB2("=== STOP\n");
 102         sta |= I2C_PCA_CON_STO;
 103         sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 104         pca_set_con(adap, sta);
 105 }
 106
 107 /*
 108  * Send the slave address and R/W bit
 109  *
 110  * returns after the address has been sent
 111  */
 112 static int pca_address(struct i2c_algo_pca_data *adap,
 113                        struct i2c_msg *msg)
 114 {
 115         int sta = pca_get_con(adap);
 116         int addr;
 117
 118         addr = ((0x7f & msg->addr) << 1);
 119         if (msg->flags & I2C_M_RD)
 120                 addr |= 1;
 121         DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
 122              msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
 123
 124         pca_outw(adap, I2C_PCA_DAT, addr);
 125
 126         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 127         pca_set_con(adap, sta);
 128
 129         return pca_wait(adap);
 130 }
 131
 132 /*
 133  * Transmit a byte.
 134  *
 135  * Returns after the byte has been transmitted
 136  */
 137 static int pca_tx_byte(struct i2c_algo_pca_data *adap,
 138                        __u8 b)
 139 {
 140         int sta = pca_get_con(adap);
 141         DEB2("=== WRITE %#04x\n", b);
 142         pca_outw(adap, I2C_PCA_DAT, b);
 143
 144         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 145         pca_set_con(adap, sta);
 146
 147         return pca_wait(adap);
 148 }
 149
 150 /*
 151  * Receive a byte
 152  *
 153  * returns immediately.
 154  */
 155 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
 156                         __u8 *b, int ack)
 157 {
 158         *b = pca_inw(adap, I2C_PCA_DAT);
 159         DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
 160 }
 161
 162 /*
 163  * Setup ACK or NACK for next received byte and wait for it to arrive.
 164  *
 165  * Returns after next byte has arrived.
 166  */
 167 static int pca_rx_ack(struct i2c_algo_pca_data *adap,
 168                       int ack)
 169 {
 170         int sta = pca_get_con(adap);
 171
 172         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
 173
 174         if (ack)
 175                 sta |= I2C_PCA_CON_AA;
 176
 177         pca_set_con(adap, sta);
 178         return pca_wait(adap);
 179 }
 180
 181 static int pca_xfer(struct i2c_adapter *i2c_adap,
 182                     struct i2c_msg *msgs,
 183                     int num)
 184 {
 185         struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
 186         struct i2c_msg *msg = NULL;
 187         int curmsg;
 188         int numbytes = 0;
 189         int state;
 190         int ret;
 191         int completed = 1;
 192         unsigned long timeout = jiffies + i2c_adap->timeout;
 193
 194         while ((state = pca_status(adap)) != 0xf8) {
 195                 if (time_before(jiffies, timeout)) {
 196                         msleep(10);
 197                 } else {
 198                         dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
 199                                 "%#04x\n", state);
 200                         return -EBUSY;
 201                 }
 202         }
 203
 204         DEB1("{{{ XFER %d messages\n", num);
 205
 206         if (i2c_debug >= 2) {
 207                 for (curmsg = 0; curmsg < num; curmsg++) {
 208                         int addr, i;
 209                         msg = &msgs[curmsg];
 210
 211                         addr = (0x7f & msg->addr) ;
 212
 213                         if (msg->flags & I2C_M_RD)
 214                                 printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
 215                                        curmsg, msg->len, addr, (addr << 1) | 1);
 216                         else {
 217                                 printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
 218                                        curmsg, msg->len, addr, addr << 1,
 219                                        msg->len == 0 ? "" : ", ");
 220                                 for (i = 0; i < msg->len; i++)
 221                                         printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
 222                                 printk("]\n");
 223                         }
 224                 }
 225         }
 226
 227         curmsg = 0;
 228         ret = -EIO;
 229         while (curmsg < num) {
 230                 state = pca_status(adap);
 231
 232                 DEB3("STATE is 0x%02x\n", state);
 233                 msg = &msgs[curmsg];
 234
 235                 switch (state) {
 236                 case 0xf8: /* On reset or stop the bus is idle */
 237                         completed = pca_start(adap);
 238                         break;
 239
 240                 case 0x08: /* A START condition has been transmitted */
 241                 case 0x10: /* A repeated start condition has been transmitted */
 242                         completed = pca_address(adap, msg);
 243                         break;
 244
 245                 case 0x18: /* SLA+W has been transmitted; ACK has been received */
 246                 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
 247                         if (numbytes < msg->len) {
 248                                 completed = pca_tx_byte(adap,
 249                                                         msg->buf[numbytes]);
 250                                 numbytes++;
 251                                 break;
 252                         }
 253                         curmsg++; numbytes = 0;
 254                         if (curmsg == num)
 255                                 pca_stop(adap);
 256                         else
 257                                 completed = pca_repeated_start(adap);
 258                         break;
 259
 260                 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
 261                         DEB2("NOT ACK received after SLA+W\n");
 262                         pca_stop(adap);
 263                         ret = -ENXIO;
 264                         goto out;
 265
 266                 case 0x40: /* SLA+R has been transmitted; ACK has been received */
 267                         completed = pca_rx_ack(adap, msg->len > 1);
 268                         break;
 269
 270                 case 0x50: /* Data bytes has been received; ACK has been returned */
 271                         if (numbytes < msg->len) {
 272                                 pca_rx_byte(adap, &msg->buf[numbytes], 1);
 273                                 numbytes++;
 274                                 completed = pca_rx_ack(adap,
 275                                                        numbytes < msg->len - 1);
 276                                 break;
 277                         }
 278                         curmsg++; numbytes = 0;
 279                         if (curmsg == num)
 280                                 pca_stop(adap);
 281                         else
 282                                 completed = pca_repeated_start(adap);
 283                         break;
 284
 285                 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
 286                         DEB2("NOT ACK received after SLA+R\n");
 287                         pca_stop(adap);
 288                         ret = -ENXIO;
 289                         goto out;
 290
 291                 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
 292                         DEB2("NOT ACK received after data byte\n");
 293                         pca_stop(adap);
 294                         goto out;
 295
 296                 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
 297                         DEB2("Arbitration lost\n");
 298                         /*
 299                          * The PCA9564 data sheet (2006-09-01) says "A
 300                          * START condition will be transmitted when the
 301                          * bus becomes free (STOP or SCL and SDA high)"
 302                          * when the STA bit is set (p. 11).
 303                          *
 304                          * In case this won't work, try pca_reset()
 305                          * instead.
 306                          */
 307                         pca_start(adap);
 308                         goto out;
 309
 310                 case 0x58: /* Data byte has been received; NOT ACK has been returned */
 311                         if (numbytes == msg->len - 1) {
 312                                 pca_rx_byte(adap, &msg->buf[numbytes], 0);
 313                                 curmsg++; numbytes = 0;
 314                                 if (curmsg == num)
 315                                         pca_stop(adap);
 316                                 else
 317                                         completed = pca_repeated_start(adap);
 318                         } else {
 319                                 DEB2("NOT ACK sent after data byte received. "
 320                                      "Not final byte. numbytes %d. len %d\n",
 321                                      numbytes, msg->len);
 322                                 pca_stop(adap);
 323                                 goto out;
 324                         }
 325                         break;
 326                 case 0x70: /* Bus error - SDA stuck low */
 327                         DEB2("BUS ERROR - SDA Stuck low\n");
 328                         pca_reset(adap);
 329                         goto out;
 330                 case 0x90: /* Bus error - SCL stuck low */
 331                         DEB2("BUS ERROR - SCL Stuck low\n");
 332                         pca_reset(adap);
 333                         goto out;
 334                 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
 335                         DEB2("BUS ERROR - Illegal START or STOP\n");
 336                         pca_reset(adap);
 337                         goto out;
 338                 default:
 339                         dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
 340                         break;
 341                 }
 342
 343                 if (!completed)
 344                         goto out;
 345         }
 346
 347         ret = curmsg;
 348  out:
 349         DEB1("}}} transferred %d/%d messages. "
 350              "status is %#04x. control is %#04x\n",
 351              curmsg, num, pca_status(adap),
 352              pca_get_con(adap));
 353         return ret;
 354 }
 355
 356 static u32 pca_func(struct i2c_adapter *adap)
 357 {
 358         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 359 }
 360
 361 static const struct i2c_algorithm pca_algo = {
 362         .master_xfer    = pca_xfer,
 363         .functionality  = pca_func,
 364 };
 365
 366 static unsigned int pca_probe_chip(struct i2c_adapter *adap)
 367 {
 368         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 369         /* The trick here is to check if there is an indirect register
 370          * available. If there is one, we will read the value we first
 371          * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
 372          * we wrote on I2C_PCA_ADR
 373          */
 374         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 375         pca_outw(pca_data, I2C_PCA_IND, 0xAA);
 376         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
 377         pca_outw(pca_data, I2C_PCA_IND, 0x00);
 378         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 379         if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
 380                 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
 381                 return I2C_PCA_CHIP_9665;
 382         } else {
 383                 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
 384                 return I2C_PCA_CHIP_9564;
 385         }
 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                 /* Ignore the reset function from the module,
 460                  * we can use the parallel bus reset
 461                  */
 462                 pca_data->reset_chip = pca9665_reset;
 463
 464                 if (pca_data->i2c_clock > 1265800) {
 465                         printk(KERN_WARNING "%s: I2C clock speed too high."
 466                                 " Using 1265.8kHz.\n", adap->name);
 467                         pca_data->i2c_clock = 1265800;
 468                 }
 469
 470                 if (pca_data->i2c_clock < 60300) {
 471                         printk(KERN_WARNING "%s: I2C clock speed too low."
 472                                 " Using 60.3kHz.\n", adap->name);
 473                         pca_data->i2c_clock = 60300;
 474                 }
 475
 476                 /* To avoid integer overflow, use clock/100 for calculations */
 477                 clock = pca_clock(pca_data) / 100;
 478
 479                 if (pca_data->i2c_clock > 10000) {
 480                         mode = I2C_PCA_MODE_TURBO;
 481                         min_tlow = 14;
 482                         min_thi  = 5;
 483                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 484                 } else if (pca_data->i2c_clock > 4000) {
 485                         mode = I2C_PCA_MODE_FASTP;
 486                         min_tlow = 17;
 487                         min_thi  = 9;
 488                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 489                 } else if (pca_data->i2c_clock > 1000) {
 490                         mode = I2C_PCA_MODE_FAST;
 491                         min_tlow = 44;
 492                         min_thi  = 20;
 493                         raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
 494                 } else {
 495                         mode = I2C_PCA_MODE_STD;
 496                         min_tlow = 157;
 497                         min_thi  = 134;
 498                         raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
 499                 }
 500
 501                 /* The minimum clock that respects the thi/tlow = 134/157 is
 502                  * 64800 Hz. Below that, we have to fix the tlow to 255 and
 503                  * calculate the thi factor.
 504                  */
 505                 if (clock < 648) {
 506                         tlow = 255;
 507                         thi = 1000000 - clock * raise_fall_time;
 508                         thi /= (I2C_PCA_OSC_PER * clock) - tlow;
 509                 } else {
 510                         tlow = (1000000 - clock * raise_fall_time) * min_tlow;
 511                         tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
 512                         thi = tlow * min_thi / min_tlow;
 513                 }
 514
 515                 pca_reset(pca_data);
 516
 517                 printk(KERN_INFO
 518                      "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
 519
 520                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE);
 521                 pca_outw(pca_data, I2C_PCA_IND, mode);
 522                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
 523                 pca_outw(pca_data, I2C_PCA_IND, tlow);
 524                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
 525                 pca_outw(pca_data, I2C_PCA_IND, thi);
 526
 527                 pca_set_con(pca_data, I2C_PCA_CON_ENSIO);
 528         }
 529         udelay(500); /* 500 us for oscilator to stabilise */
 530
 531         return 0;
 532 }
 533
 534 /*
 535  * registering functions to load algorithms at runtime
 536  */
 537 int i2c_pca_add_bus(struct i2c_adapter *adap)
 538 {
 539         int rval;
 540
 541         rval = pca_init(adap);
 542         if (rval)
 543                 return rval;
 544
 545         return i2c_add_adapter(adap);
 546 }
 547 EXPORT_SYMBOL(i2c_pca_add_bus);
 548
 549 int i2c_pca_add_numbered_bus(struct i2c_adapter *adap)
 550 {
 551         int rval;
 552
 553         rval = pca_init(adap);
 554         if (rval)
 555                 return rval;
 556
 557         return i2c_add_numbered_adapter(adap);
 558 }
 559 EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
 560
 561 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
 562         "Wolfram Sang <w.sang@pengutronix.de>");
 563 MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
 564 MODULE_LICENSE("GPL");
 565
 566 module_param(i2c_debug, int, 0);