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
  22/* With some changes from KyÃ¶sti MÃ¤lkki <kmalkki@cc.hut.fi> and
  23   Frodo Looijaard <frodol@dds.nl> ,and also from Martin Bailey
  24   <mbailey@littlefeet-inc.com> */
  25
  26/* Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
  27   messages, proper stop/repstart signaling during receive,
  28   added detect code */
  29
  30#include <linux/kernel.h>
  31#include <linux/module.h>
  32#include <linux/delay.h>
  33#include <linux/slab.h>
  34#include <linux/init.h>
  35#include <linux/errno.h>
  36#include <linux/i2c.h>
  37#include <linux/i2c-algo-pcf.h>
  38#include "i2c-algo-pcf.h"
  39
  40
  41#define DEB2(x) if (i2c_debug>=2) x
  42#define DEB3(x) if (i2c_debug>=3) x /* print several statistical values*/
  43#define DEBPROTO(x) if (i2c_debug>=9) x;
  44        /* debug the protocol by showing transferred bits */
  45#define DEF_TIMEOUT 16
  46
  47/* module parameters:
  48 */
  49static int i2c_debug;
  50
  51/* --- setting states on the bus with the right timing: --------------- */
  52
  53#define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
  54#define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
  55#define get_own(adap) adap->getown(adap->data)
  56#define get_clock(adap) adap->getclock(adap->data)
  57#define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
  58#define i2c_inb(adap) adap->getpcf(adap->data, 0)
  59
  60/* --- other auxiliary functions -------------------------------------- */
  61
  62static void i2c_start(struct i2c_algo_pcf_data *adap) 
  63{
  64        DEBPROTO(printk("S "));
  65        set_pcf(adap, 1, I2C_PCF_START);
  66}
  67
  68static void i2c_repstart(struct i2c_algo_pcf_data *adap) 
  69{
  70        DEBPROTO(printk(" Sr "));
  71        set_pcf(adap, 1, I2C_PCF_REPSTART);
  72}
  73
  74
  75static void i2c_stop(struct i2c_algo_pcf_data *adap) 
  76{
  77        DEBPROTO(printk("P\n"));
  78        set_pcf(adap, 1, I2C_PCF_STOP);
  79}
  80
  81static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
  82{
  83        DEB2(printk(KERN_INFO
  84                "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
  85                 *status));
  86
  87        /* Cleanup from LAB -- reset and enable ESO.
  88         * This resets the PCF8584; since we've lost the bus, no
  89         * further attempts should be made by callers to clean up
  90         * (no i2c_stop() etc.)
  91         */
  92        set_pcf(adap, 1, I2C_PCF_PIN);
  93        set_pcf(adap, 1, I2C_PCF_ESO);
  94
  95        /* We pause for a time period sufficient for any running
  96         * I2C transaction to complete -- the arbitration logic won't
  97         * work properly until the next START is seen.
  98         * It is assumed the bus driver or client has set a proper value.
  99         *
 100         * REVISIT: should probably use msleep instead of mdelay if we
 101         * know we can sleep.
 102         */
 103        if (adap->lab_mdelay)
 104                mdelay(adap->lab_mdelay);
 105
 106        DEB2(printk(KERN_INFO
 107                "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
 108                get_pcf(adap, 1)));
 109}
 110
 111static int wait_for_bb(struct i2c_algo_pcf_data *adap) {
 112
 113        int timeout = DEF_TIMEOUT;
 114        int status;
 115
 116        status = get_pcf(adap, 1);
 117#ifndef STUB_I2C
 118        while (timeout-- && !(status & I2C_PCF_BB)) {
 119                udelay(100); /* wait for 100 us */
 120                status = get_pcf(adap, 1);
 121        }
 122#endif
 123        if (timeout <= 0) {
 124                printk(KERN_ERR "Timeout waiting for Bus Busy\n");
 125        }
 126        
 127        return (timeout<=0);
 128}
 129
 130
 131static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status) {
 132
 133        int timeout = DEF_TIMEOUT;
 134
 135        *status = get_pcf(adap, 1);
 136#ifndef STUB_I2C
 137        while (timeout-- && (*status & I2C_PCF_PIN)) {
 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#endif
 146        if (timeout <= 0)
 147                return(-1);
 148        else
 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", get_pcf(adap, 1)));
 168
 169        /* S1=0x80: S0 selected, serial interface off */
 170        set_pcf(adap, 1, I2C_PCF_PIN);
 171        /* check to see S1 now used as R/W ctrl -
 172           PCF8584 does that when ESO is zero */
 173        if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
 174                DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
 175                return -ENXIO; /* definetly not PCF8584 */
 176        }
 177
 178        /* load own address in S0, effective address is (own << 1)      */
 179        i2c_outb(adap, get_own(adap));
 180        /* check it's really written */
 181        if ((temp = i2c_inb(adap)) != get_own(adap)) {
 182                DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
 183                return -ENXIO;
 184        }
 185
 186        /* S1=0xA0, next byte in S2                                     */
 187        set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
 188        /* check to see S2 now selected */
 189        if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
 190                DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
 191                return -ENXIO;
 192        }
 193
 194        /* load clock register S2                                       */
 195        i2c_outb(adap, get_clock(adap));
 196        /* check it's really written, the only 5 lowest bits does matter */
 197        if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
 198                DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
 199                return -ENXIO;
 200        }
 201
 202        /* Enable serial interface, idle, S0 selected                   */
 203        set_pcf(adap, 1, I2C_PCF_IDLE);
 204
 205        /* check to see PCF is really idled and we can access status register */
 206        if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
 207                DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
 208                return -ENXIO;
 209        }
 210        
 211        printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");
 212
 213        return 0;
 214}
 215
 216
 217/* ----- Utility functions
 218 */
 219
 220static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
 221                         int count, int last)
 222{
 223        struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 224        int wrcount, status, timeout;
 225    
 226        for (wrcount=0; wrcount<count; ++wrcount) {
 227                DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
 228                                buf[wrcount]&0xff));
 229                i2c_outb(adap, buf[wrcount]);
 230                timeout = wait_for_pin(adap, &status);
 231                if (timeout) {
 232                        if (timeout == -EINTR) {
 233                                /* arbitration lost */
 234                                return -EINTR;
 235                        }
 236                        i2c_stop(adap);
 237                        dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
 238                        return -EREMOTEIO; /* got a better one ?? */
 239                }
 240#ifndef STUB_I2C
 241                if (status & I2C_PCF_LRB) {
 242                        i2c_stop(adap);
 243                        dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
 244                        return -EREMOTEIO; /* got a better one ?? */
 245                }
 246#endif
 247        }
 248        if (last) {
 249                i2c_stop(adap);
 250        }
 251        else {
 252                i2c_repstart(adap);
 253        }
 254
 255        return (wrcount);
 256}
 257
 258
 259static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
 260                         int count, int last)
 261{
 262        int i, status;
 263        struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 264        int wfp;
 265
 266        /* increment number of bytes to read by one -- read dummy byte */
 267        for (i = 0; i <= count; i++) {
 268
 269                if ((wfp = wait_for_pin(adap, &status))) {
 270                        if (wfp == -EINTR) {
 271                                /* arbitration lost */
 272                                return -EINTR;
 273                        }
 274                        i2c_stop(adap);
 275                        dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
 276                        return (-1);
 277                }
 278
 279#ifndef STUB_I2C
 280                if ((status & I2C_PCF_LRB) && (i != count)) {
 281                        i2c_stop(adap);
 282                        dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
 283                        return (-1);
 284                }
 285#endif
 286                
 287                if (i == count - 1) {
 288                        set_pcf(adap, 1, I2C_PCF_ESO);
 289                } else 
 290                if (i == count) {
 291                        if (last) {
 292                                i2c_stop(adap);
 293                        } else {
 294                                i2c_repstart(adap);
 295                        }
 296                };
 297
 298                if (i) {
 299                        buf[i - 1] = i2c_inb(adap);
 300                } else {
 301                        i2c_inb(adap); /* dummy read */
 302                }
 303        }
 304
 305        return (i - 1);
 306}
 307
 308
 309static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
 310                         struct i2c_msg *msg)
 311{
 312        unsigned short flags = msg->flags;
 313        unsigned char addr;
 314
 315        addr = msg->addr << 1;
 316        if (flags & I2C_M_RD)
 317                addr |= 1;
 318        if (flags & I2C_M_REV_DIR_ADDR)
 319                addr ^= 1;
 320        i2c_outb(adap, addr);
 321
 322        return 0;
 323}
 324
 325static int pcf_xfer(struct i2c_adapter *i2c_adap,
 326                    struct i2c_msg *msgs, 
 327                    int num)
 328{
 329        struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 330        struct i2c_msg *pmsg;
 331        int i;
 332        int ret=0, timeout, status;
 333    
 334        if (adap->xfer_begin)
 335                adap->xfer_begin(adap->data);
 336
 337        /* Check for bus busy */
 338        timeout = wait_for_bb(adap);
 339        if (timeout) {
 340                DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
 341                            "Timeout waiting for BB in pcf_xfer\n");)
 342                i = -EIO;
 343                goto out;
 344        }
 345        
 346        for (i = 0;ret >= 0 && i < num; i++) {
 347                pmsg = &msgs[i];
 348
 349                DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
 350                     pmsg->flags & I2C_M_RD ? "read" : "write",
 351                     pmsg->len, pmsg->addr, i + 1, num);)
 352    
 353                ret = pcf_doAddress(adap, pmsg);
 354
 355                /* Send START */
 356                if (i == 0) {
 357                        i2c_start(adap); 
 358                }
 359    
 360                /* Wait for PIN (pending interrupt NOT) */
 361                timeout = wait_for_pin(adap, &status);
 362                if (timeout) {
 363                        if (timeout == -EINTR) {
 364                                /* arbitration lost */
 365                                i = -EINTR;
 366                                goto out;
 367                        }
 368                        i2c_stop(adap);
 369                        DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
 370                                    "for PIN(1) in pcf_xfer\n");)
 371                        i = -EREMOTEIO;
 372                        goto out;
 373                }
 374    
 375#ifndef STUB_I2C
 376                /* Check LRB (last rcvd bit - slave ack) */
 377                if (status & I2C_PCF_LRB) {
 378                        i2c_stop(adap);
 379                        DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
 380                        i = -EREMOTEIO;
 381                        goto out;
 382                }
 383#endif
 384    
 385                DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
 386                            i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
 387    
 388                /* Read */
 389                if (pmsg->flags & I2C_M_RD) {
 390                        /* read bytes into buffer*/
 391                        ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
 392                                            (i + 1 == num));
 393        
 394                        if (ret != pmsg->len) {
 395                                DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 396                                            "only read %d bytes.\n",ret));
 397                        } else {
 398                                DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
 399                        }
 400                } else { /* Write */
 401                        ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
 402                                            (i + 1 == num));
 403        
 404                        if (ret != pmsg->len) {
 405                                DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 406                                            "only wrote %d bytes.\n",ret));
 407                        } else {
 408                                DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
 409                        }
 410                }
 411        }
 412
 413out:
 414        if (adap->xfer_end)
 415                adap->xfer_end(adap->data);
 416        return (i);
 417}
 418
 419static u32 pcf_func(struct i2c_adapter *adap)
 420{
 421        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | 
 422               I2C_FUNC_PROTOCOL_MANGLING;
 423}
 424
 425/* -----exported algorithm data: -------------------------------------  */
 426
 427static const struct i2c_algorithm pcf_algo = {
 428        .master_xfer    = pcf_xfer,
 429        .functionality  = pcf_func,
 430};
 431
 432/* 
 433 * registering functions to load algorithms at runtime 
 434 */
 435int i2c_pcf_add_bus(struct i2c_adapter *adap)
 436{
 437        struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
 438        int rval;
 439
 440        DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
 441
 442        /* register new adapter to i2c module... */
 443        adap->algo = &pcf_algo;
 444        adap->timeout = 100;
 445
 446        if ((rval = pcf_init_8584(pcf_adap)))
 447                return rval;
 448
 449        rval = i2c_add_adapter(adap);
 450
 451        return rval;
 452}
 453EXPORT_SYMBOL(i2c_pcf_add_bus);
 454
 455MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
 456MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
 457MODULE_LICENSE("GPL");
 458
 459module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
 460MODULE_PARM_DESC(i2c_debug,
 461        "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");
 462