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 "opt_platform.h"
  47
  48 #include <sys/param.h>
  49 #include <sys/kernel.h>
  50 #include <sys/systm.h>
  51 #include <sys/module.h>
  52 #include <sys/bus.h>
  53 #include <sys/uio.h>
  54
  55 #ifdef FDT
  56 #include <dev/ofw/ofw_bus.h>
  57 #include <dev/ofw/ofw_bus_subr.h>
  58 #include <dev/fdt/fdt_common.h>
  59 #endif
  60
  61 #include <dev/iicbus/iiconf.h>
  62 #include <dev/iicbus/iicbus.h>
  63
  64 #include <dev/smbus/smbconf.h>
  65
  66 #include "iicbus_if.h"
  67 #include "iicbb_if.h"
  68
  69 struct iicbb_softc {
  70         device_t iicbus;
  71         int udelay;             /* signal toggle delay in usec */
  72 };
  73
  74 static int iicbb_attach(device_t);
  75 static void iicbb_child_detached(device_t, device_t);
  76 static int iicbb_detach(device_t);
  77 static int iicbb_print_child(device_t, device_t);
  78 static int iicbb_probe(device_t);
  79
  80 static int iicbb_callback(device_t, int, caddr_t);
  81 static int iicbb_start(device_t, u_char, int);
  82 static int iicbb_stop(device_t);
  83 static int iicbb_write(device_t, const char *, int, int *, int);
  84 static int iicbb_read(device_t, char *, int, int *, int, int);
  85 static int iicbb_reset(device_t, u_char, u_char, u_char *);
  86 static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs);
  87 #ifdef FDT
  88 static phandle_t iicbb_get_node(device_t, device_t);
  89 #endif
  90
  91 static device_method_t iicbb_methods[] = {
  92         /* device interface */
  93         DEVMETHOD(device_probe,         iicbb_probe),
  94         DEVMETHOD(device_attach,        iicbb_attach),
  95         DEVMETHOD(device_detach,        iicbb_detach),
  96
  97         /* bus interface */
  98         DEVMETHOD(bus_child_detached,   iicbb_child_detached),
  99         DEVMETHOD(bus_print_child,      iicbb_print_child),
 100
 101         /* iicbus interface */
 102         DEVMETHOD(iicbus_callback,      iicbb_callback),
 103         DEVMETHOD(iicbus_start,         iicbb_start),
 104         DEVMETHOD(iicbus_repeated_start, iicbb_start),
 105         DEVMETHOD(iicbus_stop,          iicbb_stop),
 106         DEVMETHOD(iicbus_write,         iicbb_write),
 107         DEVMETHOD(iicbus_read,          iicbb_read),
 108         DEVMETHOD(iicbus_reset,         iicbb_reset),
 109         DEVMETHOD(iicbus_transfer,      iicbb_transfer),
 110
 111 #ifdef FDT
 112         /* ofw_bus interface */
 113         DEVMETHOD(ofw_bus_get_node,     iicbb_get_node),
 114 #endif
 115
 116         { 0, 0 }
 117 };
 118
 119 driver_t iicbb_driver = {
 120         "iicbb",
 121         iicbb_methods,
 122         sizeof(struct iicbb_softc),
 123 };
 124
 125 devclass_t iicbb_devclass;
 126
 127 static int
 128 iicbb_probe(device_t dev)
 129 {
 130         device_set_desc(dev, "I2C bit-banging driver");
 131
 132         return (0);
 133 }
 134
 135 static int
 136 iicbb_attach(device_t dev)
 137 {
 138         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 139
 140         sc->iicbus = device_add_child(dev, "iicbus", -1);
 141         if (!sc->iicbus)
 142                 return (ENXIO);
 143         sc->udelay = 10;                /* 10 uS default */
 144         bus_generic_attach(dev);
 145
 146         return (0);
 147 }
 148
 149 static int
 150 iicbb_detach(device_t dev)
 151 {
 152         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 153         device_t child;
 154
 155         /*
 156          * We need to save child because the detach indirectly causes
 157          * sc->iicbus to be zeroed.  Since we added the device
 158          * unconditionally in iicbb_attach, we need to make sure we
 159          * delete it here.  See iicbb_child_detached.  We need that
 160          * callback in case newbus detached our children w/o detaching
 161          * us (say iicbus is a module and unloaded w/o iicbb being
 162          * unloaded).
 163          */
 164         child = sc->iicbus;
 165         bus_generic_detach(dev);
 166         if (child)
 167                 device_delete_child(dev, child);
 168
 169         return (0);
 170 }
 171
 172 #ifdef FDT
 173 static phandle_t
 174 iicbb_get_node(device_t bus, device_t dev)
 175 {
 176
 177         /* We only have one child, the I2C bus, which needs our own node. */
 178         return (ofw_bus_get_node(bus));
 179 }
 180 #endif
 181
 182 static void
 183 iicbb_child_detached( device_t dev, device_t child )
 184 {
 185         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 186
 187         if (child == sc->iicbus)
 188                 sc->iicbus = NULL;
 189 }
 190
 191 static int
 192 iicbb_print_child(device_t bus, device_t dev)
 193 {
 194         int error;
 195         int retval = 0;
 196         u_char oldaddr;
 197
 198         retval += bus_print_child_header(bus, dev);
 199         /* retrieve the interface I2C address */
 200         error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
 201         if (error == IIC_ENOADDR) {
 202                 retval += printf(" on %s master-only\n",
 203                                  device_get_nameunit(bus));
 204         } else {
 205                 /* restore the address */
 206                 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
 207
 208                 retval += printf(" on %s addr 0x%x\n",
 209                                  device_get_nameunit(bus), oldaddr & 0xff);
 210         }
 211
 212         return (retval);
 213 }
 214
 215 #define I2C_SETSDA(sc,dev,val) do {                     \
 216         IICBB_SETSDA(device_get_parent(dev), val);      \
 217         DELAY(sc->udelay);                              \
 218         } while (0)
 219
 220 #define I2C_SETSCL(dev,val) do {                        \
 221         iicbb_setscl(dev, val, 100);                    \
 222         } while (0)
 223
 224 #define I2C_SET(sc,dev,ctrl,data) do {                  \
 225         I2C_SETSCL(dev, ctrl);                          \
 226         I2C_SETSDA(sc, dev, data);                      \
 227         } while (0)
 228
 229 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
 230
 231 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
 232
 233 static int i2c_debug = 0;
 234 #define I2C_DEBUG(x)    do {                                    \
 235                                 if (i2c_debug) (x);             \
 236                         } while (0)
 237
 238 #define I2C_LOG(format,args...) do {                            \
 239                                         printf(format, args);   \
 240                                 } while (0)
 241
 242 static void
 243 iicbb_setscl(device_t dev, int val, int timeout)
 244 {
 245         struct iicbb_softc *sc = device_get_softc(dev);
 246         int k = 0;
 247
 248         IICBB_SETSCL(device_get_parent(dev), val);
 249         DELAY(sc->udelay);
 250
 251         while (val && !I2C_GETSCL(dev) && k++ < timeout) {
 252                 IICBB_SETSCL(device_get_parent(dev), val);
 253                 DELAY(sc->udelay);
 254         }
 255
 256         return;
 257 }
 258
 259 static void
 260 iicbb_one(device_t dev, int timeout)
 261 {
 262         struct iicbb_softc *sc = device_get_softc(dev);
 263
 264         I2C_SET(sc,dev,0,1);
 265         I2C_SET(sc,dev,1,1);
 266         I2C_SET(sc,dev,0,1);
 267         return;
 268 }
 269
 270 static void
 271 iicbb_zero(device_t dev, int timeout)
 272 {
 273         struct iicbb_softc *sc = device_get_softc(dev);
 274
 275         I2C_SET(sc,dev,0,0);
 276         I2C_SET(sc,dev,1,0);
 277         I2C_SET(sc,dev,0,0);
 278         return;
 279 }
 280
 281 /*
 282  * Waiting for ACKNOWLEDGE.
 283  *
 284  * When a chip is being addressed or has received data it will issue an
 285  * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
 286  * (set it to high level) and then release the CLOCK line.
 287  * Now it must wait for the SLAVE to pull the DATA line low.
 288  * Actually on the bus this looks like a START condition so nothing happens
 289  * because of the fact that the IC's that have not been addressed are doing
 290  * nothing.
 291  *
 292  * When the SLAVE has pulled this line low the MASTER will take the CLOCK
 293  * line low and then the SLAVE will release the SDA (data) line.
 294  */
 295 static int
 296 iicbb_ack(device_t dev, int timeout)
 297 {
 298         struct iicbb_softc *sc = device_get_softc(dev);
 299         int noack;
 300         int k = 0;
 301
 302         I2C_SET(sc,dev,0,1);
 303         I2C_SET(sc,dev,1,1);
 304         do {
 305                 noack = I2C_GETSDA(dev);
 306                 if (!noack)
 307                         break;
 308                 DELAY(1);
 309                 k++;
 310         } while (k < timeout);
 311
 312         I2C_SET(sc,dev,0,1);
 313         I2C_DEBUG(printf("%c ",noack?'-':'+'));
 314
 315         return (noack);
 316 }
 317
 318 static void
 319 iicbb_sendbyte(device_t dev, u_char data, int timeout)
 320 {
 321         int i;
 322
 323         for (i=7; i>=0; i--) {
 324                 if (data&(1<<i)) {
 325                         iicbb_one(dev, timeout);
 326                 } else {
 327                         iicbb_zero(dev, timeout);
 328                 }
 329         }
 330         I2C_DEBUG(printf("w%02x",(int)data));
 331         return;
 332 }
 333
 334 static u_char
 335 iicbb_readbyte(device_t dev, int last, int timeout)
 336 {
 337         struct iicbb_softc *sc = device_get_softc(dev);
 338         int i;
 339         unsigned char data=0;
 340
 341         I2C_SET(sc,dev,0,1);
 342         for (i=7; i>=0; i--)
 343         {
 344                 I2C_SET(sc,dev,1,1);
 345                 if (I2C_GETSDA(dev))
 346                         data |= (1<<i);
 347                 I2C_SET(sc,dev,0,1);
 348         }
 349         if (last) {
 350                 iicbb_one(dev, timeout);
 351         } else {
 352                 iicbb_zero(dev, timeout);
 353         }
 354         I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
 355         return data;
 356 }
 357
 358 static int
 359 iicbb_callback(device_t dev, int index, caddr_t data)
 360 {
 361         return (IICBB_CALLBACK(device_get_parent(dev), index, data));
 362 }
 363
 364 static int
 365 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
 366 {
 367         return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
 368 }
 369
 370 static int
 371 iicbb_start(device_t dev, u_char slave, int timeout)
 372 {
 373         struct iicbb_softc *sc = device_get_softc(dev);
 374         int error;
 375
 376         I2C_DEBUG(printf("<"));
 377
 378         I2C_SET(sc,dev,1,1);
 379         I2C_SET(sc,dev,1,0);
 380         I2C_SET(sc,dev,0,0);
 381
 382         /* send address */
 383         iicbb_sendbyte(dev, slave, timeout);
 384
 385         /* check for ack */
 386         if (iicbb_ack(dev, timeout)) {
 387                 error = IIC_ENOACK;
 388                 goto error;
 389         }
 390
 391         return(0);
 392
 393 error:
 394         iicbb_stop(dev);
 395         return (error);
 396 }
 397
 398 static int
 399 iicbb_stop(device_t dev)
 400 {
 401         struct iicbb_softc *sc = device_get_softc(dev);
 402
 403         I2C_SET(sc,dev,0,0);
 404         I2C_SET(sc,dev,1,0);
 405         I2C_SET(sc,dev,1,1);
 406         I2C_DEBUG(printf(">"));
 407         I2C_DEBUG(printf("\n"));
 408         return (0);
 409 }
 410
 411 static int
 412 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
 413 {
 414         int bytes, error = 0;
 415
 416         bytes = 0;
 417         while (len) {
 418                 /* send byte */
 419                 iicbb_sendbyte(dev,(u_char)*buf++, timeout);
 420
 421                 /* check for ack */
 422                 if (iicbb_ack(dev, timeout)) {
 423                         error = IIC_ENOACK;
 424                         goto error;
 425                 }
 426                 bytes ++;
 427                 len --;
 428         }
 429
 430 error:
 431         *sent = bytes;
 432         return (error);
 433 }
 434
 435 static int
 436 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
 437 {
 438         int bytes;
 439
 440         bytes = 0;
 441         while (len) {
 442                 /* XXX should insert delay here */
 443                 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
 444
 445                 bytes ++;
 446                 len --;
 447         }
 448
 449         *read = bytes;
 450         return (0);
 451 }
 452
 453 static int
 454 iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
 455 {
 456         int error;
 457
 458         error = IICBB_PRE_XFER(device_get_parent(dev));
 459         if (error)
 460                 return (error);
 461
 462         error = iicbus_transfer_gen(dev, msgs, nmsgs);
 463
 464         IICBB_POST_XFER(device_get_parent(dev));
 465         return (error);
 466 }
 467
 468 DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0);
 469
 470 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
 471 MODULE_VERSION(iicbb, IICBB_MODVER);