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/errno.h>
  28 #include <linux/i2c.h>
  29 #include <linux/i2c-algo-pca.h>
  30
  31 #define DEB1(fmt, args...) do { if (i2c_debug >= 1)                     \
  32                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  33 #define DEB2(fmt, args...) do { if (i2c_debug >= 2)                     \
  34                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  35 #define DEB3(fmt, args...) do { if (i2c_debug >= 3)                     \
  36                                  printk(KERN_DEBUG fmt, ## args); } while (0)
  37
  38 static int i2c_debug;
  39
  40 #define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val)
  41 #define pca_inw(adap, reg) adap->read_byte(adap->data, reg)
  42
  43 #define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
  44 #define pca_clock(adap) adap->i2c_clock
  45 #define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
  46 #define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
  47 #define pca_wait(adap) adap->wait_for_completion(adap->data)
  48
  49 static void pca_reset(struct i2c_algo_pca_data *adap)
  50 {
  51         if (adap->chip == I2C_PCA_CHIP_9665) {
  52                 /* Ignore the reset function from the module,
  53                  * we can use the parallel bus reset.
  54                  */
  55                 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET);
  56                 pca_outw(adap, I2C_PCA_IND, 0xA5);
  57                 pca_outw(adap, I2C_PCA_IND, 0x5A);
  58         } else {
  59                 adap->reset_chip(adap->data);
  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;
 121
 122         addr = ((0x7f & msg->addr) << 1);
 123         if (msg->flags & I2C_M_RD)
 124                 addr |= 1;
 125         DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
 126              msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
 127
 128         pca_outw(adap, I2C_PCA_DAT, addr);
 129
 130         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 131         pca_set_con(adap, sta);
 132
 133         return pca_wait(adap);
 134 }
 135
 136 /*
 137  * Transmit a byte.
 138  *
 139  * Returns after the byte has been transmitted
 140  */
 141 static int pca_tx_byte(struct i2c_algo_pca_data *adap,
 142                        __u8 b)
 143 {
 144         int sta = pca_get_con(adap);
 145         DEB2("=== WRITE %#04x\n", b);
 146         pca_outw(adap, I2C_PCA_DAT, b);
 147
 148         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 149         pca_set_con(adap, sta);
 150
 151         return pca_wait(adap);
 152 }
 153
 154 /*
 155  * Receive a byte
 156  *
 157  * returns immediately.
 158  */
 159 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
 160                         __u8 *b, int ack)
 161 {
 162         *b = pca_inw(adap, I2C_PCA_DAT);
 163         DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
 164 }
 165
 166 /*
 167  * Setup ACK or NACK for next received byte and wait for it to arrive.
 168  *
 169  * Returns after next byte has arrived.
 170  */
 171 static int pca_rx_ack(struct i2c_algo_pca_data *adap,
 172                       int ack)
 173 {
 174         int sta = pca_get_con(adap);
 175
 176         sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
 177
 178         if (ack)
 179                 sta |= I2C_PCA_CON_AA;
 180
 181         pca_set_con(adap, sta);
 182         return pca_wait(adap);
 183 }
 184
 185 static int pca_xfer(struct i2c_adapter *i2c_adap,
 186                     struct i2c_msg *msgs,
 187                     int num)
 188 {
 189         struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
 190         struct i2c_msg *msg = NULL;
 191         int curmsg;
 192         int numbytes = 0;
 193         int state;
 194         int ret;
 195         int completed = 1;
 196         unsigned long timeout = jiffies + i2c_adap->timeout;
 197
 198         while ((state = pca_status(adap)) != 0xf8) {
 199                 if (time_before(jiffies, timeout)) {
 200                         msleep(10);
 201                 } else {
 202                         dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
 203                                 "%#04x\n", state);
 204                         return -EBUSY;
 205                 }
 206         }
 207
 208         DEB1("{{{ XFER %d messages\n", num);
 209
 210         if (i2c_debug >= 2) {
 211                 for (curmsg = 0; curmsg < num; curmsg++) {
 212                         int addr, i;
 213                         msg = &msgs[curmsg];
 214
 215                         addr = (0x7f & msg->addr) ;
 216
 217                         if (msg->flags & I2C_M_RD)
 218                                 printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
 219                                        curmsg, msg->len, addr, (addr << 1) | 1);
 220                         else {
 221                                 printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
 222                                        curmsg, msg->len, addr, addr << 1,
 223                                        msg->len == 0 ? "" : ", ");
 224                                 for (i = 0; i < msg->len; i++)
 225                                         printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
 226                                 printk("]\n");
 227                         }
 228                 }
 229         }
 230
 231         curmsg = 0;
 232         ret = -EIO;
 233         while (curmsg < num) {
 234                 state = pca_status(adap);
 235
 236                 DEB3("STATE is 0x%02x\n", state);
 237                 msg = &msgs[curmsg];
 238
 239                 switch (state) {
 240                 case 0xf8: /* On reset or stop the bus is idle */
 241                         completed = pca_start(adap);
 242                         break;
 243
 244                 case 0x08: /* A START condition has been transmitted */
 245                 case 0x10: /* A repeated start condition has been transmitted */
 246                         completed = pca_address(adap, msg);
 247                         break;
 248
 249                 case 0x18: /* SLA+W has been transmitted; ACK has been received */
 250                 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
 251                         if (numbytes < msg->len) {
 252                                 completed = pca_tx_byte(adap,
 253                                                         msg->buf[numbytes]);
 254                                 numbytes++;
 255                                 break;
 256                         }
 257                         curmsg++; numbytes = 0;
 258                         if (curmsg == num)
 259                                 pca_stop(adap);
 260                         else
 261                                 completed = pca_repeated_start(adap);
 262                         break;
 263
 264                 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
 265                         DEB2("NOT ACK received after SLA+W\n");
 266                         pca_stop(adap);
 267                         ret = -ENXIO;
 268                         goto out;
 269
 270                 case 0x40: /* SLA+R has been transmitted; ACK has been received */
 271                         completed = pca_rx_ack(adap, msg->len > 1);
 272                         break;
 273
 274                 case 0x50: /* Data bytes has been received; ACK has been returned */
 275                         if (numbytes < msg->len) {
 276                                 pca_rx_byte(adap, &msg->buf[numbytes], 1);
 277                                 numbytes++;
 278                                 completed = pca_rx_ack(adap,
 279                                                        numbytes < msg->len - 1);
 280                                 break;
 281                         }
 282                         curmsg++; numbytes = 0;
 283                         if (curmsg == num)
 284                                 pca_stop(adap);
 285                         else
 286                                 completed = pca_repeated_start(adap);
 287                         break;
 288
 289                 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
 290                         DEB2("NOT ACK received after SLA+R\n");
 291                         pca_stop(adap);
 292                         ret = -ENXIO;
 293                         goto out;
 294
 295                 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
 296                         DEB2("NOT ACK received after data byte\n");
 297                         pca_stop(adap);
 298                         goto out;
 299
 300                 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
 301                         DEB2("Arbitration lost\n");
 302                         /*
 303                          * The PCA9564 data sheet (2006-09-01) says "A
 304                          * START condition will be transmitted when the
 305                          * bus becomes free (STOP or SCL and SDA high)"
 306                          * when the STA bit is set (p. 11).
 307                          *
 308                          * In case this won't work, try pca_reset()
 309                          * instead.
 310                          */
 311                         pca_start(adap);
 312                         goto out;
 313
 314                 case 0x58: /* Data byte has been received; NOT ACK has been returned */
 315                         if (numbytes == msg->len - 1) {
 316                                 pca_rx_byte(adap, &msg->buf[numbytes], 0);
 317                                 curmsg++; numbytes = 0;
 318                                 if (curmsg == num)
 319                                         pca_stop(adap);
 320                                 else
 321                                         completed = pca_repeated_start(adap);
 322                         } else {
 323                                 DEB2("NOT ACK sent after data byte received. "
 324                                      "Not final byte. numbytes %d. len %d\n",
 325                                      numbytes, msg->len);
 326                                 pca_stop(adap);
 327                                 goto out;
 328                         }
 329                         break;
 330                 case 0x70: /* Bus error - SDA stuck low */
 331                         DEB2("BUS ERROR - SDA Stuck low\n");
 332                         pca_reset(adap);
 333                         goto out;
 334                 case 0x90: /* Bus error - SCL stuck low */
 335                         DEB2("BUS ERROR - SCL Stuck low\n");
 336                         pca_reset(adap);
 337                         goto out;
 338                 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
 339                         DEB2("BUS ERROR - Illegal START or STOP\n");
 340                         pca_reset(adap);
 341                         goto out;
 342                 default:
 343                         dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
 344                         break;
 345                 }
 346
 347                 if (!completed)
 348                         goto out;
 349         }
 350
 351         ret = curmsg;
 352  out:
 353         DEB1("}}} transferred %d/%d messages. "
 354              "status is %#04x. control is %#04x\n",
 355              curmsg, num, pca_status(adap),
 356              pca_get_con(adap));
 357         return ret;
 358 }
 359
 360 static u32 pca_func(struct i2c_adapter *adap)
 361 {
 362         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 363 }
 364
 365 static const struct i2c_algorithm pca_algo = {
 366         .master_xfer    = pca_xfer,
 367         .functionality  = pca_func,
 368 };
 369
 370 static unsigned int pca_probe_chip(struct i2c_adapter *adap)
 371 {
 372         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 373         /* The trick here is to check if there is an indirect register
 374          * available. If there is one, we will read the value we first
 375          * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
 376          * we wrote on I2C_PCA_ADR
 377          */
 378         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 379         pca_outw(pca_data, I2C_PCA_IND, 0xAA);
 380         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
 381         pca_outw(pca_data, I2C_PCA_IND, 0x00);
 382         pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 383         if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
 384                 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
 385                 pca_data->chip = I2C_PCA_CHIP_9665;
 386         } else {
 387                 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
 388                 pca_data->chip = I2C_PCA_CHIP_9564;
 389         }
 390         return pca_data->chip;
 391 }
 392
 393 static int pca_init(struct i2c_adapter *adap)
 394 {
 395         struct i2c_algo_pca_data *pca_data = adap->algo_data;
 396
 397         adap->algo = &pca_algo;
 398
 399         if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
 400                 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
 401                 int clock;
 402
 403                 if (pca_data->i2c_clock > 7) {
 404                         switch (pca_data->i2c_clock) {
 405                         case 330000:
 406                                 pca_data->i2c_clock = I2C_PCA_CON_330kHz;
 407                                 break;
 408                         case 288000:
 409                                 pca_data->i2c_clock = I2C_PCA_CON_288kHz;
 410                                 break;
 411                         case 217000:
 412                                 pca_data->i2c_clock = I2C_PCA_CON_217kHz;
 413                                 break;
 414                         case 146000:
 415                                 pca_data->i2c_clock = I2C_PCA_CON_146kHz;
 416                                 break;
 417                         case 88000:
 418                                 pca_data->i2c_clock = I2C_PCA_CON_88kHz;
 419                                 break;
 420                         case 59000:
 421                                 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 422                                 break;
 423                         case 44000:
 424                                 pca_data->i2c_clock = I2C_PCA_CON_44kHz;
 425                                 break;
 426                         case 36000:
 427                                 pca_data->i2c_clock = I2C_PCA_CON_36kHz;
 428                                 break;
 429                         default:
 430                                 printk(KERN_WARNING
 431                                         "%s: Invalid I2C clock speed selected."
 432                                         " Using default 59kHz.\n", adap->name);
 433                         pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 434                         }
 435                 } else {
 436                         printk(KERN_WARNING "%s: "
 437                                 "Choosing the clock frequency based on "
 438                                 "index is deprecated."
 439                                 " Use the nominal frequency.\n", adap->name);
 440                 }
 441
 442                 pca_reset(pca_data);
 443
 444                 clock = pca_clock(pca_data);
 445                 printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
 446                      adap->name, freqs[clock]);
 447
 448                 pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock);
 449         } else {
 450                 int clock;
 451                 int mode;
 452                 int tlow, thi;
 453                 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */
 454                 int min_tlow, min_thi;
 455                 /* These values are the maximum raise and fall values allowed
 456                  * by the I2C operation mode (Standard, Fast or Fast+)
 457                  * They are used (added) below to calculate the clock dividers
 458                  * of PCA9665. Note that they are slightly different of the
 459                  * real maximum, to allow the change on mode exactly on the
 460                  * maximum clock rate for each mode
 461                  */
 462                 int raise_fall_time;
 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 > 1000000) {
 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 > 400000) {
 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 > 100000) {
 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);