sys/dev/iicbus/iicbb.c

   1 /*-
   2  * Copyright (c) 1998, 2001 Nicolas Souchu
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28 __FBSDID("$FreeBSD$");
  29
  30 /*
  31  * Generic I2C bit-banging code
  32  *
  33  * Example:
  34  *
  35  *      iicbus
  36  *       /  \
  37  *    iicbb pcf
  38  *     |  \
  39  *   bti2c lpbb
  40  *
  41  * From Linux I2C generic interface
  42  * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
  43  *
  44  */
  45
  46 #include <sys/param.h>
  47 #include <sys/kernel.h>
  48 #include <sys/systm.h>
  49 #include <sys/module.h>
  50 #include <sys/bus.h>
  51 #include <sys/uio.h>
  52
  53
  54 #include <dev/iicbus/iiconf.h>
  55 #include <dev/iicbus/iicbus.h>
  56
  57 #include <dev/smbus/smbconf.h>
  58
  59 #include "iicbus_if.h"
  60 #include "iicbb_if.h"
  61
  62 struct iicbb_softc {
  63         device_t iicbus;
  64         int udelay;             /* signal toggle delay in usec */
  65 };
  66
  67 static int iicbb_attach(device_t);
  68 static void iicbb_child_detached(device_t, device_t);
  69 static int iicbb_detach(device_t);
  70 static int iicbb_print_child(device_t, device_t);
  71 static int iicbb_probe(device_t);
  72
  73 static int iicbb_callback(device_t, int, caddr_t);
  74 static int iicbb_start(device_t, u_char, int);
  75 static int iicbb_stop(device_t);
  76 static int iicbb_write(device_t, const char *, int, int *, int);
  77 static int iicbb_read(device_t, char *, int, int *, int, int);
  78 static int iicbb_reset(device_t, u_char, u_char, u_char *);
  79 static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs);
  80
  81 static device_method_t iicbb_methods[] = {
  82         /* device interface */
  83         DEVMETHOD(device_probe,         iicbb_probe),
  84         DEVMETHOD(device_attach,        iicbb_attach),
  85         DEVMETHOD(device_detach,        iicbb_detach),
  86
  87         /* bus interface */
  88         DEVMETHOD(bus_child_detached,   iicbb_child_detached),
  89         DEVMETHOD(bus_print_child,      iicbb_print_child),
  90
  91         /* iicbus interface */
  92         DEVMETHOD(iicbus_callback,      iicbb_callback),
  93         DEVMETHOD(iicbus_start,         iicbb_start),
  94         DEVMETHOD(iicbus_repeated_start, iicbb_start),
  95         DEVMETHOD(iicbus_stop,          iicbb_stop),
  96         DEVMETHOD(iicbus_write,         iicbb_write),
  97         DEVMETHOD(iicbus_read,          iicbb_read),
  98         DEVMETHOD(iicbus_reset,         iicbb_reset),
  99         DEVMETHOD(iicbus_transfer,      iicbb_transfer),
 100
 101         { 0, 0 }
 102 };
 103
 104 driver_t iicbb_driver = {
 105         "iicbb",
 106         iicbb_methods,
 107         sizeof(struct iicbb_softc),
 108 };
 109
 110 devclass_t iicbb_devclass;
 111
 112 static int
 113 iicbb_probe(device_t dev)
 114 {
 115         device_set_desc(dev, "I2C bit-banging driver");
 116
 117         return (0);
 118 }
 119
 120 static int
 121 iicbb_attach(device_t dev)
 122 {
 123         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 124
 125         sc->iicbus = device_add_child(dev, "iicbus", -1);
 126         if (!sc->iicbus)
 127                 return (ENXIO);
 128         sc->udelay = 10;                /* 10 uS default */
 129         bus_generic_attach(dev);
 130
 131         return (0);
 132 }
 133
 134 static int
 135 iicbb_detach(device_t dev)
 136 {
 137         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 138         device_t child;
 139
 140         /*
 141          * We need to save child because the detach indirectly causes
 142          * sc->iicbus to be zeroed.  Since we added the device
 143          * unconditionally in iicbb_attach, we need to make sure we
 144          * delete it here.  See iicbb_child_detached.  We need that
 145          * callback in case newbus detached our children w/o detaching
 146          * us (say iicbus is a module and unloaded w/o iicbb being
 147          * unloaded).
 148          */
 149         child = sc->iicbus;
 150         bus_generic_detach(dev);
 151         if (child)
 152                 device_delete_child(dev, child);
 153
 154         return (0);
 155 }
 156
 157 static void
 158 iicbb_child_detached( device_t dev, device_t child )
 159 {
 160         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 161
 162         if (child == sc->iicbus)
 163                 sc->iicbus = NULL;
 164 }
 165
 166 static int
 167 iicbb_print_child(device_t bus, device_t dev)
 168 {
 169         int error;
 170         int retval = 0;
 171         u_char oldaddr;
 172
 173         retval += bus_print_child_header(bus, dev);
 174         /* retrieve the interface I2C address */
 175         error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
 176         if (error == IIC_ENOADDR) {
 177                 retval += printf(" on %s master-only\n",
 178                                  device_get_nameunit(bus));
 179         } else {
 180                 /* restore the address */
 181                 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
 182
 183                 retval += printf(" on %s addr 0x%x\n",
 184                                  device_get_nameunit(bus), oldaddr & 0xff);
 185         }
 186
 187         return (retval);
 188 }
 189
 190 #define I2C_SETSDA(sc,dev,val) do {                     \
 191         IICBB_SETSDA(device_get_parent(dev), val);      \
 192         DELAY(sc->udelay);                              \
 193         } while (0)
 194
 195 #define I2C_SETSCL(dev,val) do {                        \
 196         iicbb_setscl(dev, val, 100);                    \
 197         } while (0)
 198
 199 #define I2C_SET(sc,dev,ctrl,data) do {                  \
 200         I2C_SETSCL(dev, ctrl);                          \
 201         I2C_SETSDA(sc, dev, data);                      \
 202         } while (0)
 203
 204 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
 205
 206 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
 207
 208 static int i2c_debug = 0;
 209 #define I2C_DEBUG(x)    do {                                    \
 210                                 if (i2c_debug) (x);             \
 211                         } while (0)
 212
 213 #define I2C_LOG(format,args...) do {                            \
 214                                         printf(format, args);   \
 215                                 } while (0)
 216
 217 static void
 218 iicbb_setscl(device_t dev, int val, int timeout)
 219 {
 220         struct iicbb_softc *sc = device_get_softc(dev);
 221         int k = 0;
 222
 223         IICBB_SETSCL(device_get_parent(dev), val);
 224         DELAY(sc->udelay);
 225
 226         while (val && !I2C_GETSCL(dev) && k++ < timeout) {
 227                 IICBB_SETSCL(device_get_parent(dev), val);
 228                 DELAY(sc->udelay);
 229         }
 230
 231         return;
 232 }
 233
 234 static void
 235 iicbb_one(device_t dev, int timeout)
 236 {
 237         struct iicbb_softc *sc = device_get_softc(dev);
 238
 239         I2C_SET(sc,dev,0,1);
 240         I2C_SET(sc,dev,1,1);
 241         I2C_SET(sc,dev,0,1);
 242         return;
 243 }
 244
 245 static void
 246 iicbb_zero(device_t dev, int timeout)
 247 {
 248         struct iicbb_softc *sc = device_get_softc(dev);
 249
 250         I2C_SET(sc,dev,0,0);
 251         I2C_SET(sc,dev,1,0);
 252         I2C_SET(sc,dev,0,0);
 253         return;
 254 }
 255
 256 /*
 257  * Waiting for ACKNOWLEDGE.
 258  *
 259  * When a chip is being addressed or has received data it will issue an
 260  * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
 261  * (set it to high level) and then release the CLOCK line.
 262  * Now it must wait for the SLAVE to pull the DATA line low.
 263  * Actually on the bus this looks like a START condition so nothing happens
 264  * because of the fact that the IC's that have not been addressed are doing
 265  * nothing.
 266  *
 267  * When the SLAVE has pulled this line low the MASTER will take the CLOCK
 268  * line low and then the SLAVE will release the SDA (data) line.
 269  */
 270 static int
 271 iicbb_ack(device_t dev, int timeout)
 272 {
 273         struct iicbb_softc *sc = device_get_softc(dev);
 274         int noack;
 275         int k = 0;
 276
 277         I2C_SET(sc,dev,0,1);
 278         I2C_SET(sc,dev,1,1);
 279         do {
 280                 noack = I2C_GETSDA(dev);
 281                 if (!noack)
 282                         break;
 283                 DELAY(1);
 284                 k++;
 285         } while (k < timeout);
 286
 287         I2C_SET(sc,dev,0,1);
 288         I2C_DEBUG(printf("%c ",noack?'-':'+'));
 289
 290         return (noack);
 291 }
 292
 293 static void
 294 iicbb_sendbyte(device_t dev, u_char data, int timeout)
 295 {
 296         int i;
 297
 298         for (i=7; i>=0; i--) {
 299                 if (data&(1<<i)) {
 300                         iicbb_one(dev, timeout);
 301                 } else {
 302                         iicbb_zero(dev, timeout);
 303                 }
 304         }
 305         I2C_DEBUG(printf("w%02x",(int)data));
 306         return;
 307 }
 308
 309 static u_char
 310 iicbb_readbyte(device_t dev, int last, int timeout)
 311 {
 312         struct iicbb_softc *sc = device_get_softc(dev);
 313         int i;
 314         unsigned char data=0;
 315
 316         I2C_SET(sc,dev,0,1);
 317         for (i=7; i>=0; i--)
 318         {
 319                 I2C_SET(sc,dev,1,1);
 320                 if (I2C_GETSDA(dev))
 321                         data |= (1<<i);
 322                 I2C_SET(sc,dev,0,1);
 323         }
 324         if (last) {
 325                 iicbb_one(dev, timeout);
 326         } else {
 327                 iicbb_zero(dev, timeout);
 328         }
 329         I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
 330         return data;
 331 }
 332
 333 static int
 334 iicbb_callback(device_t dev, int index, caddr_t data)
 335 {
 336         return (IICBB_CALLBACK(device_get_parent(dev), index, data));
 337 }
 338
 339 static int
 340 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
 341 {
 342         return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
 343 }
 344
 345 static int
 346 iicbb_start(device_t dev, u_char slave, int timeout)
 347 {
 348         struct iicbb_softc *sc = device_get_softc(dev);
 349         int error;
 350
 351         I2C_DEBUG(printf("<"));
 352
 353         I2C_SET(sc,dev,1,1);
 354         I2C_SET(sc,dev,1,0);
 355         I2C_SET(sc,dev,0,0);
 356
 357         /* send address */
 358         iicbb_sendbyte(dev, slave, timeout);
 359
 360         /* check for ack */
 361         if (iicbb_ack(dev, timeout)) {
 362                 error = IIC_ENOACK;
 363                 goto error;
 364         }
 365
 366         return(0);
 367
 368 error:
 369         iicbb_stop(dev);
 370         return (error);
 371 }
 372
 373 static int
 374 iicbb_stop(device_t dev)
 375 {
 376         struct iicbb_softc *sc = device_get_softc(dev);
 377
 378         I2C_SET(sc,dev,0,0);
 379         I2C_SET(sc,dev,1,0);
 380         I2C_SET(sc,dev,1,1);
 381         I2C_DEBUG(printf(">"));
 382         I2C_DEBUG(printf("\n"));
 383         return (0);
 384 }
 385
 386 static int
 387 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
 388 {
 389         int bytes, error = 0;
 390
 391         bytes = 0;
 392         while (len) {
 393                 /* send byte */
 394                 iicbb_sendbyte(dev,(u_char)*buf++, timeout);
 395
 396                 /* check for ack */
 397                 if (iicbb_ack(dev, timeout)) {
 398                         error = IIC_ENOACK;
 399                         goto error;
 400                 }
 401                 bytes ++;
 402                 len --;
 403         }
 404
 405 error:
 406         *sent = bytes;
 407         return (error);
 408 }
 409
 410 static int
 411 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
 412 {
 413         int bytes;
 414
 415         bytes = 0;
 416         while (len) {
 417                 /* XXX should insert delay here */
 418                 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
 419
 420                 bytes ++;
 421                 len --;
 422         }
 423
 424         *read = bytes;
 425         return (0);
 426 }
 427
 428 static int
 429 iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
 430 {
 431         int error;
 432
 433         error = IICBB_PRE_XFER(device_get_parent(dev));
 434         if (error)
 435                 return (error);
 436
 437         error = iicbus_transfer_gen(dev, msgs, nmsgs);
 438
 439         IICBB_POST_XFER(device_get_parent(dev));
 440         return (error);
 441 }
 442
 443 DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0);
 444
 445 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
 446 MODULE_VERSION(iicbb, IICBB_MODVER);