linux/drivers/i2c/algos/i2c-algo-pca.c
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   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
  24static 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
  35static 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        } else {
  45                adap->reset_chip(adap->data);
  46        }
  47}
  48
  49/*
  50 * Generate a start condition on the i2c bus.
  51 *
  52 * returns after the start condition has occurred
  53 */
  54static int pca_start(struct i2c_algo_pca_data *adap)
  55{
  56        int sta = pca_get_con(adap);
  57        DEB2("=== START\n");
  58        sta |= I2C_PCA_CON_STA;
  59        sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  60        pca_set_con(adap, sta);
  61        return pca_wait(adap);
  62}
  63
  64/*
  65 * Generate a repeated start condition on the i2c bus
  66 *
  67 * return after the repeated start condition has occurred
  68 */
  69static int pca_repeated_start(struct i2c_algo_pca_data *adap)
  70{
  71        int sta = pca_get_con(adap);
  72        DEB2("=== REPEATED START\n");
  73        sta |= I2C_PCA_CON_STA;
  74        sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
  75        pca_set_con(adap, sta);
  76        return pca_wait(adap);
  77}
  78
  79/*
  80 * Generate a stop condition on the i2c bus
  81 *
  82 * returns after the stop condition has been generated
  83 *
  84 * STOPs do not generate an interrupt or set the SI flag, since the
  85 * part returns the idle state (0xf8). Hence we don't need to
  86 * pca_wait here.
  87 */
  88static void pca_stop(struct i2c_algo_pca_data *adap)
  89{
  90        int sta = pca_get_con(adap);
  91        DEB2("=== STOP\n");
  92        sta |= I2C_PCA_CON_STO;
  93        sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
  94        pca_set_con(adap, sta);
  95}
  96
  97/*
  98 * Send the slave address and R/W bit
  99 *
 100 * returns after the address has been sent
 101 */
 102static int pca_address(struct i2c_algo_pca_data *adap,
 103                       struct i2c_msg *msg)
 104{
 105        int sta = pca_get_con(adap);
 106        int addr = i2c_8bit_addr_from_msg(msg);
 107
 108        DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
 109             msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
 110
 111        pca_outw(adap, I2C_PCA_DAT, addr);
 112
 113        sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 114        pca_set_con(adap, sta);
 115
 116        return pca_wait(adap);
 117}
 118
 119/*
 120 * Transmit a byte.
 121 *
 122 * Returns after the byte has been transmitted
 123 */
 124static int pca_tx_byte(struct i2c_algo_pca_data *adap,
 125                       __u8 b)
 126{
 127        int sta = pca_get_con(adap);
 128        DEB2("=== WRITE %#04x\n", b);
 129        pca_outw(adap, I2C_PCA_DAT, b);
 130
 131        sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
 132        pca_set_con(adap, sta);
 133
 134        return pca_wait(adap);
 135}
 136
 137/*
 138 * Receive a byte
 139 *
 140 * returns immediately.
 141 */
 142static void pca_rx_byte(struct i2c_algo_pca_data *adap,
 143                        __u8 *b, int ack)
 144{
 145        *b = pca_inw(adap, I2C_PCA_DAT);
 146        DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
 147}
 148
 149/*
 150 * Setup ACK or NACK for next received byte and wait for it to arrive.
 151 *
 152 * Returns after next byte has arrived.
 153 */
 154static int pca_rx_ack(struct i2c_algo_pca_data *adap,
 155                      int ack)
 156{
 157        int sta = pca_get_con(adap);
 158
 159        sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
 160
 161        if (ack)
 162                sta |= I2C_PCA_CON_AA;
 163
 164        pca_set_con(adap, sta);
 165        return pca_wait(adap);
 166}
 167
 168static int pca_xfer(struct i2c_adapter *i2c_adap,
 169                    struct i2c_msg *msgs,
 170                    int num)
 171{
 172        struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
 173        struct i2c_msg *msg = NULL;
 174        int curmsg;
 175        int numbytes = 0;
 176        int state;
 177        int ret;
 178        int completed = 1;
 179        unsigned long timeout = jiffies + i2c_adap->timeout;
 180
 181        while ((state = pca_status(adap)) != 0xf8) {
 182                if (time_before(jiffies, timeout)) {
 183                        msleep(10);
 184                } else {
 185                        dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
 186                                "%#04x\n", state);
 187                        return -EBUSY;
 188                }
 189        }
 190
 191        DEB1("{{{ XFER %d messages\n", num);
 192
 193        if (i2c_debug >= 2) {
 194                for (curmsg = 0; curmsg < num; curmsg++) {
 195                        int addr, i;
 196                        msg = &msgs[curmsg];
 197
 198                        addr = (0x7f & msg->addr) ;
 199
 200                        if (msg->flags & I2C_M_RD)
 201                                printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
 202                                       curmsg, msg->len, addr, (addr << 1) | 1);
 203                        else {
 204                                printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
 205                                       curmsg, msg->len, addr, addr << 1,
 206                                       msg->len == 0 ? "" : ", ");
 207                                for (i = 0; i < msg->len; i++)
 208                                        printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
 209                                printk("]\n");
 210                        }
 211                }
 212        }
 213
 214        curmsg = 0;
 215        ret = -EIO;
 216        while (curmsg < num) {
 217                state = pca_status(adap);
 218
 219                DEB3("STATE is 0x%02x\n", state);
 220                msg = &msgs[curmsg];
 221
 222                switch (state) {
 223                case 0xf8: /* On reset or stop the bus is idle */
 224                        completed = pca_start(adap);
 225                        break;
 226
 227                case 0x08: /* A START condition has been transmitted */
 228                case 0x10: /* A repeated start condition has been transmitted */
 229                        completed = pca_address(adap, msg);
 230                        break;
 231
 232                case 0x18: /* SLA+W has been transmitted; ACK has been received */
 233                case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
 234                        if (numbytes < msg->len) {
 235                                completed = pca_tx_byte(adap,
 236                                                        msg->buf[numbytes]);
 237                                numbytes++;
 238                                break;
 239                        }
 240                        curmsg++; numbytes = 0;
 241                        if (curmsg == num)
 242                                pca_stop(adap);
 243                        else
 244                                completed = pca_repeated_start(adap);
 245                        break;
 246
 247                case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
 248                        DEB2("NOT ACK received after SLA+W\n");
 249                        pca_stop(adap);
 250                        ret = -ENXIO;
 251                        goto out;
 252
 253                case 0x40: /* SLA+R has been transmitted; ACK has been received */
 254                        completed = pca_rx_ack(adap, msg->len > 1);
 255                        break;
 256
 257                case 0x50: /* Data bytes has been received; ACK has been returned */
 258                        if (numbytes < msg->len) {
 259                                pca_rx_byte(adap, &msg->buf[numbytes], 1);
 260                                numbytes++;
 261                                completed = pca_rx_ack(adap,
 262                                                       numbytes < msg->len - 1);
 263                                break;
 264                        }
 265                        curmsg++; numbytes = 0;
 266                        if (curmsg == num)
 267                                pca_stop(adap);
 268                        else
 269                                completed = pca_repeated_start(adap);
 270                        break;
 271
 272                case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
 273                        DEB2("NOT ACK received after SLA+R\n");
 274                        pca_stop(adap);
 275                        ret = -ENXIO;
 276                        goto out;
 277
 278                case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
 279                        DEB2("NOT ACK received after data byte\n");
 280                        pca_stop(adap);
 281                        goto out;
 282
 283                case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
 284                        DEB2("Arbitration lost\n");
 285                        /*
 286                         * The PCA9564 data sheet (2006-09-01) says "A
 287                         * START condition will be transmitted when the
 288                         * bus becomes free (STOP or SCL and SDA high)"
 289                         * when the STA bit is set (p. 11).
 290                         *
 291                         * In case this won't work, try pca_reset()
 292                         * instead.
 293                         */
 294                        pca_start(adap);
 295                        goto out;
 296
 297                case 0x58: /* Data byte has been received; NOT ACK has been returned */
 298                        if (numbytes == msg->len - 1) {
 299                                pca_rx_byte(adap, &msg->buf[numbytes], 0);
 300                                curmsg++; numbytes = 0;
 301                                if (curmsg == num)
 302                                        pca_stop(adap);
 303                                else
 304                                        completed = pca_repeated_start(adap);
 305                        } else {
 306                                DEB2("NOT ACK sent after data byte received. "
 307                                     "Not final byte. numbytes %d. len %d\n",
 308                                     numbytes, msg->len);
 309                                pca_stop(adap);
 310                                goto out;
 311                        }
 312                        break;
 313                case 0x70: /* Bus error - SDA stuck low */
 314                        DEB2("BUS ERROR - SDA Stuck low\n");
 315                        pca_reset(adap);
 316                        goto out;
 317                case 0x90: /* Bus error - SCL stuck low */
 318                        DEB2("BUS ERROR - SCL Stuck low\n");
 319                        pca_reset(adap);
 320                        goto out;
 321                case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
 322                        DEB2("BUS ERROR - Illegal START or STOP\n");
 323                        pca_reset(adap);
 324                        goto out;
 325                default:
 326                        dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
 327                        break;
 328                }
 329
 330                if (!completed)
 331                        goto out;
 332        }
 333
 334        ret = curmsg;
 335 out:
 336        DEB1("}}} transferred %d/%d messages. "
 337             "status is %#04x. control is %#04x\n",
 338             curmsg, num, pca_status(adap),
 339             pca_get_con(adap));
 340        return ret;
 341}
 342
 343static u32 pca_func(struct i2c_adapter *adap)
 344{
 345        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 346}
 347
 348static const struct i2c_algorithm pca_algo = {
 349        .master_xfer    = pca_xfer,
 350        .functionality  = pca_func,
 351};
 352
 353static unsigned int pca_probe_chip(struct i2c_adapter *adap)
 354{
 355        struct i2c_algo_pca_data *pca_data = adap->algo_data;
 356        /* The trick here is to check if there is an indirect register
 357         * available. If there is one, we will read the value we first
 358         * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
 359         * we wrote on I2C_PCA_ADR
 360         */
 361        pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 362        pca_outw(pca_data, I2C_PCA_IND, 0xAA);
 363        pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
 364        pca_outw(pca_data, I2C_PCA_IND, 0x00);
 365        pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
 366        if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
 367                printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
 368                pca_data->chip = I2C_PCA_CHIP_9665;
 369        } else {
 370                printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
 371                pca_data->chip = I2C_PCA_CHIP_9564;
 372        }
 373        return pca_data->chip;
 374}
 375
 376static int pca_init(struct i2c_adapter *adap)
 377{
 378        struct i2c_algo_pca_data *pca_data = adap->algo_data;
 379
 380        adap->algo = &pca_algo;
 381
 382        if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
 383                static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
 384                int clock;
 385
 386                if (pca_data->i2c_clock > 7) {
 387                        switch (pca_data->i2c_clock) {
 388                        case 330000:
 389                                pca_data->i2c_clock = I2C_PCA_CON_330kHz;
 390                                break;
 391                        case 288000:
 392                                pca_data->i2c_clock = I2C_PCA_CON_288kHz;
 393                                break;
 394                        case 217000:
 395                                pca_data->i2c_clock = I2C_PCA_CON_217kHz;
 396                                break;
 397                        case 146000:
 398                                pca_data->i2c_clock = I2C_PCA_CON_146kHz;
 399                                break;
 400                        case 88000:
 401                                pca_data->i2c_clock = I2C_PCA_CON_88kHz;
 402                                break;
 403                        case 59000:
 404                                pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 405                                break;
 406                        case 44000:
 407                                pca_data->i2c_clock = I2C_PCA_CON_44kHz;
 408                                break;
 409                        case 36000:
 410                                pca_data->i2c_clock = I2C_PCA_CON_36kHz;
 411                                break;
 412                        default:
 413                                printk(KERN_WARNING
 414                                        "%s: Invalid I2C clock speed selected."
 415                                        " Using default 59kHz.\n", adap->name);
 416                        pca_data->i2c_clock = I2C_PCA_CON_59kHz;
 417                        }
 418                } else {
 419                        printk(KERN_WARNING "%s: "
 420                                "Choosing the clock frequency based on "
 421                                "index is deprecated."
 422                                " Use the nominal frequency.\n", adap->name);
 423                }
 424
 425                pca_reset(pca_data);
 426
 427                clock = pca_clock(pca_data);
 428                printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
 429                     adap->name, freqs[clock]);
 430
 431                pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock);
 432        } else {
 433                int clock;
 434                int mode;
 435                int tlow, thi;
 436                /* Values can be found on PCA9665 datasheet section 7.3.2.6 */
 437                int min_tlow, min_thi;
 438                /* These values are the maximum raise and fall values allowed
 439                 * by the I2C operation mode (Standard, Fast or Fast+)
 440                 * They are used (added) below to calculate the clock dividers
 441                 * of PCA9665. Note that they are slightly different of the
 442                 * real maximum, to allow the change on mode exactly on the
 443                 * maximum clock rate for each mode
 444                 */
 445                int raise_fall_time;
 446
 447                if (pca_data->i2c_clock > 1265800) {
 448                        printk(KERN_WARNING "%s: I2C clock speed too high."
 449                                " Using 1265.8kHz.\n", adap->name);
 450                        pca_data->i2c_clock = 1265800;
 451                }
 452
 453                if (pca_data->i2c_clock < 60300) {
 454                        printk(KERN_WARNING "%s: I2C clock speed too low."
 455                                " Using 60.3kHz.\n", adap->name);
 456                        pca_data->i2c_clock = 60300;
 457                }
 458
 459                /* To avoid integer overflow, use clock/100 for calculations */
 460                clock = pca_clock(pca_data) / 100;
 461
 462                if (pca_data->i2c_clock > 1000000) {
 463                        mode = I2C_PCA_MODE_TURBO;
 464                        min_tlow = 14;
 465                        min_thi  = 5;
 466                        raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 467                } else if (pca_data->i2c_clock > 400000) {
 468                        mode = I2C_PCA_MODE_FASTP;
 469                        min_tlow = 17;
 470                        min_thi  = 9;
 471                        raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
 472                } else if (pca_data->i2c_clock > 100000) {
 473                        mode = I2C_PCA_MODE_FAST;
 474                        min_tlow = 44;
 475                        min_thi  = 20;
 476                        raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
 477                } else {
 478                        mode = I2C_PCA_MODE_STD;
 479                        min_tlow = 157;
 480                        min_thi  = 134;
 481                        raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
 482                }
 483
 484                /* The minimum clock that respects the thi/tlow = 134/157 is
 485                 * 64800 Hz. Below that, we have to fix the tlow to 255 and
 486                 * calculate the thi factor.
 487                 */
 488                if (clock < 648) {
 489                        tlow = 255;
 490                        thi = 1000000 - clock * raise_fall_time;
 491                        thi /= (I2C_PCA_OSC_PER * clock) - tlow;
 492                } else {
 493                        tlow = (1000000 - clock * raise_fall_time) * min_tlow;
 494                        tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
 495                        thi = tlow * min_thi / min_tlow;
 496                }
 497
 498                pca_reset(pca_data);
 499
 500                printk(KERN_INFO
 501                     "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
 502
 503                pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE);
 504                pca_outw(pca_data, I2C_PCA_IND, mode);
 505                pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
 506                pca_outw(pca_data, I2C_PCA_IND, tlow);
 507                pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
 508                pca_outw(pca_data, I2C_PCA_IND, thi);
 509
 510                pca_set_con(pca_data, I2C_PCA_CON_ENSIO);
 511        }
 512        udelay(500); /* 500 us for oscillator to stabilise */
 513
 514        return 0;
 515}
 516
 517/*
 518 * registering functions to load algorithms at runtime
 519 */
 520int i2c_pca_add_bus(struct i2c_adapter *adap)
 521{
 522        int rval;
 523
 524        rval = pca_init(adap);
 525        if (rval)
 526                return rval;
 527
 528        return i2c_add_adapter(adap);
 529}
 530EXPORT_SYMBOL(i2c_pca_add_bus);
 531
 532int i2c_pca_add_numbered_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_numbered_adapter(adap);
 541}
 542EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
 543
 544MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
 545        "Wolfram Sang <w.sang@pengutronix.de>");
 546MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
 547MODULE_LICENSE("GPL");
 548
 549module_param(i2c_debug, int, 0);
 550