LXR linux/drivers/i2c/algos/i2c-algo-pcf.c

   1/*
   2 * i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters
   3 *
   4 *   Copyright (C) 1995-1997 Simon G. Vogl
   5 *                 1998-2000 Hans Berglund
   6 *
   7 *  This program is free software; you can redistribute it and/or modify
   8 *  it under the terms of the GNU General Public License as published by
   9 *  the Free Software Foundation; either version 2 of the License, or
  10 *  (at your option) any later version.
  11 *
  12 *  This program is distributed in the hope that it will be useful,
  13 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  15 *  GNU General Public License for more details.
  16 *
  17 *  You should have received a copy of the GNU General Public License
  18 *  along with this program; if not, write to the Free Software
  19 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 *
  21 * With some changes from KyÃ¶sti MÃ¤lkki <kmalkki@cc.hut.fi> and
  22 * Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey
  23 * <mbailey@littlefeet-inc.com>
  24 *
  25 * Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
  26 * messages, proper stop/repstart signaling during receive, added detect code
  27 */
  28
  29#include <linux/kernel.h>
  30#include <linux/module.h>
  31#include <linux/delay.h>
  32#include <linux/init.h>
  33#include <linux/errno.h>
  34#include <linux/i2c.h>
  35#include <linux/i2c-algo-pcf.h>
  36#include "i2c-algo-pcf.h"
  37
  38
  39#define DEB2(x) if (i2c_debug >= 2) x
  40#define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */
  41#define DEBPROTO(x) if (i2c_debug >= 9) x;
  42        /* debug the protocol by showing transferred bits */
  43#define DEF_TIMEOUT 16
  44
  45/*
  46 * module parameters:
  47 */
  48static int i2c_debug;
  49
  50/* setting states on the bus with the right timing: */
  51
  52#define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
  53#define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
  54#define get_own(adap) adap->getown(adap->data)
  55#define get_clock(adap) adap->getclock(adap->data)
  56#define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
  57#define i2c_inb(adap) adap->getpcf(adap->data, 0)
  58
  59/* other auxiliary functions */
  60
  61static void i2c_start(struct i2c_algo_pcf_data *adap)
  62{
  63        DEBPROTO(printk(KERN_DEBUG "S "));
  64        set_pcf(adap, 1, I2C_PCF_START);
  65}
  66
  67static void i2c_repstart(struct i2c_algo_pcf_data *adap)
  68{
  69        DEBPROTO(printk(" Sr "));
  70        set_pcf(adap, 1, I2C_PCF_REPSTART);
  71}
  72
  73static void i2c_stop(struct i2c_algo_pcf_data *adap)
  74{
  75        DEBPROTO(printk("P\n"));
  76        set_pcf(adap, 1, I2C_PCF_STOP);
  77}
  78
  79static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
  80{
  81        DEB2(printk(KERN_INFO
  82                "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
  83                *status));
  84        /*
  85         * Cleanup from LAB -- reset and enable ESO.
  86         * This resets the PCF8584; since we've lost the bus, no
  87         * further attempts should be made by callers to clean up
  88         * (no i2c_stop() etc.)
  89         */
  90        set_pcf(adap, 1, I2C_PCF_PIN);
  91        set_pcf(adap, 1, I2C_PCF_ESO);
  92        /*
  93         * We pause for a time period sufficient for any running
  94         * I2C transaction to complete -- the arbitration logic won't
  95         * work properly until the next START is seen.
  96         * It is assumed the bus driver or client has set a proper value.
  97         *
  98         * REVISIT: should probably use msleep instead of mdelay if we
  99         * know we can sleep.
 100         */
 101        if (adap->lab_mdelay)
 102                mdelay(adap->lab_mdelay);
 103
 104        DEB2(printk(KERN_INFO
 105                "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
 106                get_pcf(adap, 1)));
 107}
 108
 109static int wait_for_bb(struct i2c_algo_pcf_data *adap)
 110{
 111
 112        int timeout = DEF_TIMEOUT;
 113        int status;
 114
 115        status = get_pcf(adap, 1);
 116
 117        while (!(status & I2C_PCF_BB) && --timeout) {
 118                udelay(100); /* wait for 100 us */
 119                status = get_pcf(adap, 1);
 120        }
 121
 122        if (timeout == 0) {
 123                printk(KERN_ERR "Timeout waiting for Bus Busy\n");
 124                return -ETIMEDOUT;
 125        }
 126
 127        return 0;
 128}
 129
 130static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
 131{
 132
 133        int timeout = DEF_TIMEOUT;
 134
 135        *status = get_pcf(adap, 1);
 136
 137        while ((*status & I2C_PCF_PIN) && --timeout) {
 138                adap->waitforpin(adap->data);
 139                *status = get_pcf(adap, 1);
 140        }
 141        if (*status & I2C_PCF_LAB) {
 142                handle_lab(adap, status);
 143                return -EINTR;
 144        }
 145
 146        if (timeout == 0)
 147                return -ETIMEDOUT;
 148
 149        return 0;
 150}
 151
 152/*
 153 * This should perform the 'PCF8584 initialization sequence' as described
 154 * in the Philips IC12 data book (1995, Aug 29).
 155 * There should be a 30 clock cycle wait after reset, I assume this
 156 * has been fulfilled.
 157 * There should be a delay at the end equal to the longest I2C message
 158 * to synchronize the BB-bit (in multimaster systems). How long is
 159 * this? I assume 1 second is always long enough.
 160 *
 161 * vdovikin: added detect code for PCF8584
 162 */
 163static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
 164{
 165        unsigned char temp;
 166
 167        DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n",
 168                                get_pcf(adap, 1)));
 169
 170        /* S1=0x80: S0 selected, serial interface off */
 171        set_pcf(adap, 1, I2C_PCF_PIN);
 172        /*
 173         * check to see S1 now used as R/W ctrl -
 174         * PCF8584 does that when ESO is zero
 175         */
 176        if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
 177                DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
 178                return -ENXIO; /* definitely not PCF8584 */
 179        }
 180
 181        /* load own address in S0, effective address is (own << 1) */
 182        i2c_outb(adap, get_own(adap));
 183        /* check it's really written */
 184        if ((temp = i2c_inb(adap)) != get_own(adap)) {
 185                DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
 186                return -ENXIO;
 187        }
 188
 189        /* S1=0xA0, next byte in S2 */
 190        set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
 191        /* check to see S2 now selected */
 192        if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
 193                DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
 194                return -ENXIO;
 195        }
 196
 197        /* load clock register S2 */
 198        i2c_outb(adap, get_clock(adap));
 199        /* check it's really written, the only 5 lowest bits does matter */
 200        if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
 201                DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
 202                return -ENXIO;
 203        }
 204
 205        /* Enable serial interface, idle, S0 selected */
 206        set_pcf(adap, 1, I2C_PCF_IDLE);
 207
 208        /* check to see PCF is really idled and we can access status register */
 209        if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
 210                DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
 211                return -ENXIO;
 212        }
 213
 214        printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");
 215
 216        return 0;
 217}
 218
 219static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
 220                         int count, int last)
 221{
 222        struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 223        int wrcount, status, timeout;
 224
 225        for (wrcount=0; wrcount<count; ++wrcount) {
 226                DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
 227                                buf[wrcount] & 0xff));
 228                i2c_outb(adap, buf[wrcount]);
 229                timeout = wait_for_pin(adap, &status);
 230                if (timeout) {
 231                        if (timeout == -EINTR)
 232                                return -EINTR; /* arbitration lost */
 233
 234                        i2c_stop(adap);
 235                        dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
 236                        return -EREMOTEIO; /* got a better one ?? */
 237                }
 238                if (status & I2C_PCF_LRB) {
 239                        i2c_stop(adap);
 240                        dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
 241                        return -EREMOTEIO; /* got a better one ?? */
 242                }
 243        }
 244        if (last)
 245                i2c_stop(adap);
 246        else
 247                i2c_repstart(adap);
 248
 249        return wrcount;
 250}
 251
 252static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
 253                         int count, int last)
 254{
 255        int i, status;
 256        struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 257        int wfp;
 258
 259        /* increment number of bytes to read by one -- read dummy byte */
 260        for (i = 0; i <= count; i++) {
 261
 262                if ((wfp = wait_for_pin(adap, &status))) {
 263                        if (wfp == -EINTR)
 264                                return -EINTR; /* arbitration lost */
 265
 266                        i2c_stop(adap);
 267                        dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
 268                        return -1;
 269                }
 270
 271                if ((status & I2C_PCF_LRB) && (i != count)) {
 272                        i2c_stop(adap);
 273                        dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
 274                        return -1;
 275                }
 276
 277                if (i == count - 1) {
 278                        set_pcf(adap, 1, I2C_PCF_ESO);
 279                } else if (i == count) {
 280                        if (last)
 281                                i2c_stop(adap);
 282                        else
 283                                i2c_repstart(adap);
 284                }
 285
 286                if (i)
 287                        buf[i - 1] = i2c_inb(adap);
 288                else
 289                        i2c_inb(adap); /* dummy read */
 290        }
 291
 292        return i - 1;
 293}
 294
 295
 296static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
 297                         struct i2c_msg *msg)
 298{
 299        unsigned short flags = msg->flags;
 300        unsigned char addr;
 301
 302        addr = msg->addr << 1;
 303        if (flags & I2C_M_RD)
 304                addr |= 1;
 305        if (flags & I2C_M_REV_DIR_ADDR)
 306                addr ^= 1;
 307        i2c_outb(adap, addr);
 308
 309        return 0;
 310}
 311
 312static int pcf_xfer(struct i2c_adapter *i2c_adap,
 313                    struct i2c_msg *msgs,
 314                    int num)
 315{
 316        struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 317        struct i2c_msg *pmsg;
 318        int i;
 319        int ret=0, timeout, status;
 320
 321        if (adap->xfer_begin)
 322                adap->xfer_begin(adap->data);
 323
 324        /* Check for bus busy */
 325        timeout = wait_for_bb(adap);
 326        if (timeout) {
 327                DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
 328                            "Timeout waiting for BB in pcf_xfer\n");)
 329                i = -EIO;
 330                goto out;
 331        }
 332
 333        for (i = 0;ret >= 0 && i < num; i++) {
 334                pmsg = &msgs[i];
 335
 336                DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
 337                     pmsg->flags & I2C_M_RD ? "read" : "write",
 338                     pmsg->len, pmsg->addr, i + 1, num);)
 339
 340                ret = pcf_doAddress(adap, pmsg);
 341
 342                /* Send START */
 343                if (i == 0)
 344                        i2c_start(adap);
 345
 346                /* Wait for PIN (pending interrupt NOT) */
 347                timeout = wait_for_pin(adap, &status);
 348                if (timeout) {
 349                        if (timeout == -EINTR) {
 350                                /* arbitration lost */
 351                                i = -EINTR;
 352                                goto out;
 353                        }
 354                        i2c_stop(adap);
 355                        DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
 356                                    "for PIN(1) in pcf_xfer\n");)
 357                        i = -EREMOTEIO;
 358                        goto out;
 359                }
 360
 361                /* Check LRB (last rcvd bit - slave ack) */
 362                if (status & I2C_PCF_LRB) {
 363                        i2c_stop(adap);
 364                        DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
 365                        i = -EREMOTEIO;
 366                        goto out;
 367                }
 368
 369                DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
 370                            i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
 371
 372                if (pmsg->flags & I2C_M_RD) {
 373                        ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
 374                                            (i + 1 == num));
 375
 376                        if (ret != pmsg->len) {
 377                                DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 378                                            "only read %d bytes.\n",ret));
 379                        } else {
 380                                DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
 381                        }
 382                } else {
 383                        ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
 384                                            (i + 1 == num));
 385
 386                        if (ret != pmsg->len) {
 387                                DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 388                                            "only wrote %d bytes.\n",ret));
 389                        } else {
 390                                DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
 391                        }
 392                }
 393        }
 394
 395out:
 396        if (adap->xfer_end)
 397                adap->xfer_end(adap->data);
 398        return i;
 399}
 400
 401static u32 pcf_func(struct i2c_adapter *adap)
 402{
 403        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 404               I2C_FUNC_PROTOCOL_MANGLING;
 405}
 406
 407/* exported algorithm data: */
 408static const struct i2c_algorithm pcf_algo = {
 409        .master_xfer    = pcf_xfer,
 410        .functionality  = pcf_func,
 411};
 412
 413/*
 414 * registering functions to load algorithms at runtime
 415 */
 416int i2c_pcf_add_bus(struct i2c_adapter *adap)
 417{
 418        struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
 419        int rval;
 420
 421        DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
 422
 423        /* register new adapter to i2c module... */
 424        adap->algo = &pcf_algo;
 425
 426        if ((rval = pcf_init_8584(pcf_adap)))
 427                return rval;
 428
 429        rval = i2c_add_adapter(adap);
 430
 431        return rval;
 432}
 433EXPORT_SYMBOL(i2c_pcf_add_bus);
 434
 435MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
 436MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
 437MODULE_LICENSE("GPL");
 438
 439module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
 440MODULE_PARM_DESC(i2c_debug,
 441        "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");
 442