git.oblomov.eu Git - linux-2.6/blob - 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., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/moduleparam.h>
  24 #include <linux/delay.h>
  25 #include <linux/init.h>
  26 #include <linux/errno.h>
  27 #include <linux/i2c.h>
  28 #include <linux/i2c-algo-pca.h>
  29
  30 #define DEB1(fmt, args...) do { if (i2c_debug >= 1)                     \
  31                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  32 #define DEB2(fmt, args...) do { if (i2c_debug >= 2)                     \
  33                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  34 #define DEB3(fmt, args...) do { if (i2c_debug >= 3)                     \
  35                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  36
  37 static int i2c_debug;
  38
  39 #define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val)
  40 #define pca_inw(adap, reg) adap->read_byte(adap->data, reg)
  41
  42 #define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
  43 #define pca_clock(adap) adap->i2c_clock
  44 #define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
  45 #define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
  46 #define pca_wait(adap) adap->wait_for_completion(adap->data)
  47 #define pca_reset(adap) adap->reset_chip(adap->data)
  48
  49 static void pca9665_reset(void *pd)
  50 {
  51         struct i2c_algo_pca_data *adap = pd;
  52         pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET);
  53         pca_outw(adap, I2C_PCA_IND, 0xA5);
  54         pca_outw(adap, I2C_PCA_IND, 0x5A);
  55 }
  56
  57 /*
  58  * Generate a start condition on the i2c bus.
  59  *
  60  * returns after the start condition has occurred
  61  */
  62 static void pca_start(struct i2c_algo_pca_data *adap)
  63 {
  64         int sta = pca_get_con(adap);
  65         DEB2("=== START\n");
  66         sta |= I2C_PCA_CON_STA;
  67         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  68         pca_set_con(adap, sta);
  69         pca_wait(adap);
  70 }
  71
  72 /*
  73  * Generate a repeated start condition on the i2c bus
  74  *
  75  * return after the repeated start condition has occurred
  76  */
  77 static void pca_repeated_start(struct i2c_algo_pca_data *adap)
  78 {
  79         int sta = pca_get_con(adap);
  80         DEB2("=== REPEATED START\n");
  81         sta |= I2C_PCA_CON_STA;
  82         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  83         pca_set_con(adap, sta);
  84         pca_wait(adap);
  85 }
  86
  87 /*
  88  * Generate a stop condition on the i2c bus
  89  *
  90  * returns after the stop condition has been generated
  91  *
  92  * STOPs do not generate an interrupt or set the SI flag, since the
  93  * part returns the idle state (0xf8). Hence we don't need to
  94  * pca_wait here.
  95  */
  96 static void pca_stop(struct i2c_algo_pca_data *adap)
  97 {
  98         int sta = pca_get_con(adap);
  99         DEB2("=== STOP\n");
 100         sta |= I2C_PCA_CON_STO;
 101         sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 102         pca_set_con(adap, sta);
 103 }
 104
 105 /*
 106  * Send the slave address and R/W bit
 107  *
 108  * returns after the address has been sent
 109  */
 110 static void pca_address(struct i2c_algo_pca_data *adap,
 111                         struct i2c_msg *msg)
 112 {
 113         int sta = pca_get_con(adap);
 114         int addr;
 115
 116         addr = ( (0x7f & msg->addr) << 1 );
 117         if (msg->flags & I2C_M_RD )
 118                 addr |= 1;
 119         DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
 120              msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
 121
 122         pca_outw(adap, I2C_PCA_DAT, addr);
 123
 124         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 125         pca_set_con(adap, sta);
 126
 127         pca_wait(adap);
 128 }
 129
 130 /*
 131  * Transmit a byte.
 132  *
 133  * Returns after the byte has been transmitted
 134  */
 135 static void pca_tx_byte(struct i2c_algo_pca_data *adap,
 136                         __u8 b)
 137 {
 138         int sta = pca_get_con(adap);
 139         DEB2("=== WRITE %#04x\n", b);
 140         pca_outw(adap, I2C_PCA_DAT, b);
 141
 142         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 143         pca_set_con(adap, sta);
 144
 145         pca_wait(adap);
 146 }
 147
 148 /*
 149  * Receive a byte
 150  *
 151  * returns immediately.
 152  */
 153 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
 154                         __u8 *b, int ack)
 155 {
 156         *b = pca_inw(adap, I2C_PCA_DAT);
 157         DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
 158 }
 159
 160 /*
 161  * Setup ACK or NACK for next received byte and wait for it to arrive.
 162  *
 163  * Returns after next byte has arrived.
 164  */
 165 static void pca_rx_ack(struct i2c_algo_pca_data *adap,
 166                        int ack)
 167 {
 168         int sta = pca_get_con(adap);
 169
 170         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
 171
 172         if ( ack )
 173                 sta |= I2C_PCA_CON_AA;
 174
 175         pca_set_con(adap, sta);
 176         pca_wait(adap);
 177 }
 178
 179 static int pca_xfer(struct i2c_adapter *i2c_adap,
 180                     struct i2c_msg *msgs,
 181                     int num)
 182 {
 183         struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
 184         struct i2c_msg *msg = NULL;
 185         int curmsg;
 186         int numbytes = 0;
 187         int state;
 188         int ret;
 189         int timeout = i2c_adap->timeout;
 190
 191         while ((state = pca_status(adap)) != 0xf8 && timeout--) {
 192                 msleep(10);
 193         }
 194         if (state != 0xf8) {
 195                 dev_dbg(&i2c_adap->dev, "bus is not idle. status is %#04x\n", state);
 196                 return -EAGAIN;
 197         }
 198
 199         DEB1("{{{ XFER %d messages\n", num);
 200
 201         if (i2c_debug>=2) {
 202                 for (curmsg = 0; curmsg < num; curmsg++) {
 203                         int addr, i;
 204                         msg = &msgs[curmsg];
 205
 206                         addr = (0x7f & msg->addr) ;
 207
 208                         if (msg->flags & I2C_M_RD )
 209                                 printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
 210                                        curmsg, msg->len, addr, (addr<<1) | 1);
 211                         else {
 212                                 printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
 213                                        curmsg, msg->len, addr, addr<<1,
 214                                        msg->len == 0 ? "" : ", ");
 215                                 for(i=0; i < msg->len; i++)
 216                                         printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
 217                                 printk("]\n");
 218                         }
 219                 }
 220         }
 221
 222         curmsg = 0;
 223         ret = -EREMOTEIO;
 224         while (curmsg < num) {
 225                 state = pca_status(adap);
 226
 227                 DEB3("STATE is 0x%02x\n", state);
 228                 msg = &msgs[curmsg];
 229
 230                 switch (state) {
 231                 case 0xf8: /* On reset or stop the bus is idle */
 232                         pca_start(adap);
 233                         break;
 234
 235                 case 0x08: /* A START condition has been transmitted */
 236                 case 0x10: /* A repeated start condition has been transmitted */
 237                         pca_address(adap, msg);
 238                         break;
 239
 240                 case 0x18: /* SLA+W has been transmitted; ACK has been received */
 241                 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
 242                         if (numbytes < msg->len) {
 243                                 pca_tx_byte(adap, msg->buf[numbytes]);
 244                                 numbytes++;
 245                                 break;
 246                         }
 247                         curmsg++; numbytes = 0;
 248                         if (curmsg == num)
 249                                 pca_stop(adap);
 250                         else
 251                                 pca_repeated_start(adap);
 252                         break;
 253
 254                 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
 255                         DEB2("NOT ACK received after SLA+W\n");
 256                         pca_stop(adap);
 257                         goto out;
 258
 259                 case 0x40: /* SLA+R has been transmitted; ACK has been received */
 260                         pca_rx_ack(adap, msg->len > 1);
 261                         break;
 262
 263                 case 0x50: /* Data bytes has been received; ACK has been returned */
 264                         if (numbytes < msg->len) {
 265                                 pca_rx_byte(adap, &msg->buf[numbytes], 1);
 266                                 numbytes++;
 267                                 pca_rx_ack(adap, numbytes < msg->len - 1);
 268                                 break;
 269                         }
 270                         curmsg++; numbytes = 0;
 271                         if (curmsg == num)
 272                                 pca_stop(adap);
 273                         else
 274                                 pca_repeated_start(adap);
 275                         break;
 276
 277                 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
 278                         DEB2("NOT ACK received after SLA+R\n");
 279                         pca_stop(adap);
 280                         goto out;
 281
 282                 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
 283                         DEB2("NOT ACK received after data byte\n");
 284                         goto out;
 285
 286                 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
 287                         DEB2("Arbitration lost\n");
 288                         goto out;
 289
 290                 case 0x58: /* Data byte has been received; NOT ACK has been returned */
 291                         if ( numbytes == msg->len - 1 ) {
 292                                 pca_rx_byte(adap, &msg->buf[numbytes], 0);
 293                                 curmsg++; numbytes = 0;
 294                                 if (curmsg == num)
 295                                         pca_stop(adap);
 296                                 else
 297                                         pca_repeated_start(adap);
 298                         } else {
 299                                 DEB2("NOT ACK sent after data byte received. "
 300                                      "Not final byte. numbytes %d. len %d\n",
 301                                      numbytes, msg->len);
 302                                 pca_stop(adap);
 303                                 goto out;
 304                         }
 305                         break;
 306                 case 0x70: /* Bus error - SDA stuck low */
 307                         DEB2("BUS ERROR - SDA Stuck low\n");
 308                         pca_reset(adap);
 309                         goto out;
 310                 case 0x90: /* Bus error - SCL stuck low */
 311                         DEB2("BUS ERROR - SCL Stuck low\n");
 312                         pca_reset(adap);
 313                         goto out;
 314                 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
 315                         DEB2("BUS ERROR - Illegal START or STOP\n");
 316                         pca_reset(adap);
 317                         goto out;
 318                 default:
 319                         dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
 320                         break;
 321                 }
 322
 323         }
 324
 325         ret = curmsg;
 326  out:
 327         DEB1("}}} transfered %d/%d messages. "
 328              "status is %#04x. control is %#04x\n",
 329              curmsg, num, pca_status(adap),
 330              pca_get_con(adap));
 331         return ret;
 332 }
 333
 334 static u32 pca_func(struct i2c_adapter *adap)
 335 {
 336         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 337 }
 338
 339 static const struct i2c_algorithm pca_algo = {
 340         .master_xfer    = pca_xfer,
 341         .functionality  = pca_func,
 342 };
 343
 344 static unsigned int pca_probe_chip(struct i2c_adapter *adap)
 345 {
 346         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 347         /* The trick here is to check if there is an indirect register
 348          * available. If there is one, we will read the value we first
 349          * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
 350          * we wrote on I2C_PCA_ADR
 351          */
 352         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 353         pca_outw(pca_data, I2C_PCA_IND, 0xAA);
 354         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
 355         pca_outw(pca_data, I2C_PCA_IND, 0x00);
 356         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 357         if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
 358                 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
 359                 return I2C_PCA_CHIP_9665;
 360         } else {
 361                 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
 362                 return I2C_PCA_CHIP_9564;
 363         }
 364 }
 365
 366 static int pca_init(struct i2c_adapter *adap)
 367 {
 368         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 369
 370         adap->algo = &pca_algo;
 371
 372         if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
 373                 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
 374                 int clock;
 375
 376                 if (pca_data->i2c_clock > 7) {
 377                         switch (pca_data->i2c_clock) {
 378                         case 330000:
 379                                 pca_data->i2c_clock = I2C_PCA_CON_330kHz;
 380                                 break;
 381                         case 288000:
 382                                 pca_data->i2c_clock = I2C_PCA_CON_288kHz;
 383                                 break;
 384                         case 217000:
 385                                 pca_data->i2c_clock = I2C_PCA_CON_217kHz;
 386                                 break;
 387                         case 146000:
 388                                 pca_data->i2c_clock = I2C_PCA_CON_146kHz;
 389                                 break;
 390                         case 88000:
 391                                 pca_data->i2c_clock = I2C_PCA_CON_88kHz;
 392                                 break;
 393                         case 59000:
 394                                 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 395                                 break;
 396                         case 44000:
 397                                 pca_data->i2c_clock = I2C_PCA_CON_44kHz;
 398                                 break;
 399                         case 36000:
 400                                 pca_data->i2c_clock = I2C_PCA_CON_36kHz;
 401                                 break;
 402                         default:
 403                                 printk(KERN_WARNING
 404                                         "%s: Invalid I2C clock speed selected."
 405                                         " Using default 59kHz.\n", adap->name);
 406                         pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 407                         }
 408                 } else {
 409                         printk(KERN_WARNING "%s: "
 410                                 "Choosing the clock frequency based on "
 411                                 "index is deprecated."
 412                                 " Use the nominal frequency.\n", adap->name);
 413                 }
 414
 415                 pca_reset(pca_data);
 416
 417                 clock = pca_clock(pca_data);
 418                 printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
 419                      adap->name, freqs[clock]);
 420
 421                 pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock);
 422         } else {
 423                 int clock;
 424                 int mode;
 425                 int tlow, thi;
 426                 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */
 427                 int min_tlow, min_thi;
 428                 /* These values are the maximum raise and fall values allowed
 429                  * by the I2C operation mode (Standard, Fast or Fast+)
 430                  * They are used (added) below to calculate the clock dividers
 431                  * of PCA9665. Note that they are slightly different of the
 432                  * real maximum, to allow the change on mode exactly on the
 433                  * maximum clock rate for each mode
 434                  */
 435                 int raise_fall_time;
 436
 437                 struct i2c_algo_pca_data *pca_data = adap->algo_data;
 438
 439                 /* Ignore the reset function from the module,
 440                  * we can use the parallel bus reset
 441                  */
 442                 pca_data->reset_chip = pca9665_reset;
 443
 444                 if (pca_data->i2c_clock > 1265800) {
 445                         printk(KERN_WARNING "%s: I2C clock speed too high."
 446                                 " Using 1265.8kHz.\n", adap->name);
 447                         pca_data->i2c_clock = 1265800;
 448                 }
 449
 450                 if (pca_data->i2c_clock < 60300) {
 451                         printk(KERN_WARNING "%s: I2C clock speed too low."
 452                                 " Using 60.3kHz.\n", adap->name);
 453                         pca_data->i2c_clock = 60300;
 454                 }
 455
 456                 /* To avoid integer overflow, use clock/100 for calculations */
 457                 clock = pca_clock(pca_data) / 100;
 458
 459                 if (pca_data->i2c_clock > 10000) {
 460                         mode = I2C_PCA_MODE_TURBO;
 461                         min_tlow = 14;
 462                         min_thi  = 5;
 463                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 464                 } else if (pca_data->i2c_clock > 4000) {
 465                         mode = I2C_PCA_MODE_FASTP;
 466                         min_tlow = 17;
 467                         min_thi  = 9;
 468                         raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 469                 } else if (pca_data->i2c_clock > 1000) {
 470                         mode = I2C_PCA_MODE_FAST;
 471                         min_tlow = 44;
 472                         min_thi  = 20;
 473                         raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
 474                 } else {
 475                         mode = I2C_PCA_MODE_STD;
 476                         min_tlow = 157;
 477                         min_thi  = 134;
 478                         raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
 479                 }
 480
 481                 /* The minimum clock that respects the thi/tlow = 134/157 is
 482                  * 64800 Hz. Below that, we have to fix the tlow to 255 and
 483                  * calculate the thi factor.
 484                  */
 485                 if (clock < 648) {
 486                         tlow = 255;
 487                         thi = 1000000 - clock * raise_fall_time;
 488                         thi /= (I2C_PCA_OSC_PER * clock) - tlow;
 489                 } else {
 490                         tlow = (1000000 - clock * raise_fall_time) * min_tlow;
 491                         tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
 492                         thi = tlow * min_thi / min_tlow;
 493                 }
 494
 495                 pca_reset(pca_data);
 496
 497                 printk(KERN_INFO
 498                      "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
 499
 500                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE);
 501                 pca_outw(pca_data, I2C_PCA_IND, mode);
 502                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
 503                 pca_outw(pca_data, I2C_PCA_IND, tlow);
 504                 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
 505                 pca_outw(pca_data, I2C_PCA_IND, thi);
 506
 507                 pca_set_con(pca_data, I2C_PCA_CON_ENSIO);
 508         }
 509         udelay(500); /* 500 us for oscilator to stabilise */
 510
 511         return 0;
 512 }
 513
 514 /*
 515  * registering functions to load algorithms at runtime
 516  */
 517 int i2c_pca_add_bus(struct i2c_adapter *adap)
 518 {
 519         int rval;
 520
 521         rval = pca_init(adap);
 522         if (rval)
 523                 return rval;
 524
 525         return i2c_add_adapter(adap);
 526 }
 527 EXPORT_SYMBOL(i2c_pca_add_bus);
 528
 529 int i2c_pca_add_numbered_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_numbered_adapter(adap);
 538 }
 539 EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
 540
 541 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
 542         "Wolfram Sang <w.sang@pengutronix.de>");
 543 MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
 544 MODULE_LICENSE("GPL");
 545
 546 module_param(i2c_debug, int, 0);