sys/dev/iicbus/iicbb.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 1998, 2001 Nicolas Souchu
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 /*
  33  * Generic I2C bit-banging code
  34  *
  35  * Example:
  36  *
  37  *      iicbus
  38  *       /  \
  39  *    iicbb pcf
  40  *     |  \
  41  *   bti2c lpbb
  42  *
  43  * From Linux I2C generic interface
  44  * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
  45  *
  46  */
  47
  48 #include "opt_platform.h"
  49
  50 #include <sys/param.h>
  51 #include <sys/kernel.h>
  52 #include <sys/systm.h>
  53 #include <sys/module.h>
  54 #include <sys/bus.h>
  55 #include <sys/uio.h>
  56
  57 #ifdef FDT
  58 #include <dev/ofw/ofw_bus.h>
  59 #include <dev/ofw/ofw_bus_subr.h>
  60 #include <dev/fdt/fdt_common.h>
  61 #endif
  62
  63 #include <dev/iicbus/iiconf.h>
  64 #include <dev/iicbus/iicbus.h>
  65
  66 #include <dev/smbus/smbconf.h>
  67
  68 #include "iicbus_if.h"
  69 #include "iicbb_if.h"
  70
  71 struct iicbb_softc {
  72         device_t iicbus;
  73         int udelay;             /* signal toggle delay in usec */
  74 };
  75
  76 static int iicbb_attach(device_t);
  77 static void iicbb_child_detached(device_t, device_t);
  78 static int iicbb_detach(device_t);
  79 static int iicbb_print_child(device_t, device_t);
  80 static int iicbb_probe(device_t);
  81
  82 static int iicbb_callback(device_t, int, caddr_t);
  83 static int iicbb_start(device_t, u_char, int);
  84 static int iicbb_stop(device_t);
  85 static int iicbb_write(device_t, const char *, int, int *, int);
  86 static int iicbb_read(device_t, char *, int, int *, int, int);
  87 static int iicbb_reset(device_t, u_char, u_char, u_char *);
  88 static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs);
  89 #ifdef FDT
  90 static phandle_t iicbb_get_node(device_t, device_t);
  91 #endif
  92
  93 static device_method_t iicbb_methods[] = {
  94         /* device interface */
  95         DEVMETHOD(device_probe,         iicbb_probe),
  96         DEVMETHOD(device_attach,        iicbb_attach),
  97         DEVMETHOD(device_detach,        iicbb_detach),
  98
  99         /* bus interface */
 100         DEVMETHOD(bus_child_detached,   iicbb_child_detached),
 101         DEVMETHOD(bus_print_child,      iicbb_print_child),
 102
 103         /* iicbus interface */
 104         DEVMETHOD(iicbus_callback,      iicbb_callback),
 105         DEVMETHOD(iicbus_start,         iicbb_start),
 106         DEVMETHOD(iicbus_repeated_start, iicbb_start),
 107         DEVMETHOD(iicbus_stop,          iicbb_stop),
 108         DEVMETHOD(iicbus_write,         iicbb_write),
 109         DEVMETHOD(iicbus_read,          iicbb_read),
 110         DEVMETHOD(iicbus_reset,         iicbb_reset),
 111         DEVMETHOD(iicbus_transfer,      iicbb_transfer),
 112
 113 #ifdef FDT
 114         /* ofw_bus interface */
 115         DEVMETHOD(ofw_bus_get_node,     iicbb_get_node),
 116 #endif
 117
 118         { 0, 0 }
 119 };
 120
 121 driver_t iicbb_driver = {
 122         "iicbb",
 123         iicbb_methods,
 124         sizeof(struct iicbb_softc),
 125 };
 126
 127 devclass_t iicbb_devclass;
 128
 129 static int
 130 iicbb_probe(device_t dev)
 131 {
 132         device_set_desc(dev, "I2C bit-banging driver");
 133
 134         return (0);
 135 }
 136
 137 static int
 138 iicbb_attach(device_t dev)
 139 {
 140         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 141
 142         sc->iicbus = device_add_child(dev, "iicbus", -1);
 143         if (!sc->iicbus)
 144                 return (ENXIO);
 145         sc->udelay = 10;                /* 10 uS default */
 146         bus_generic_attach(dev);
 147
 148         return (0);
 149 }
 150
 151 static int
 152 iicbb_detach(device_t dev)
 153 {
 154
 155         bus_generic_detach(dev);
 156         device_delete_children(dev);
 157
 158         return (0);
 159 }
 160
 161 #ifdef FDT
 162 static phandle_t
 163 iicbb_get_node(device_t bus, device_t dev)
 164 {
 165
 166         /* We only have one child, the I2C bus, which needs our own node. */
 167         return (ofw_bus_get_node(bus));
 168 }
 169 #endif
 170
 171 static void
 172 iicbb_child_detached( device_t dev, device_t child )
 173 {
 174         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 175
 176         if (child == sc->iicbus)
 177                 sc->iicbus = NULL;
 178 }
 179
 180 static int
 181 iicbb_print_child(device_t bus, device_t dev)
 182 {
 183         int error;
 184         int retval = 0;
 185         u_char oldaddr;
 186
 187         retval += bus_print_child_header(bus, dev);
 188         /* retrieve the interface I2C address */
 189         error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
 190         if (error == IIC_ENOADDR) {
 191                 retval += printf(" on %s master-only\n",
 192                                  device_get_nameunit(bus));
 193         } else {
 194                 /* restore the address */
 195                 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
 196
 197                 retval += printf(" on %s addr 0x%x\n",
 198                                  device_get_nameunit(bus), oldaddr & 0xff);
 199         }
 200
 201         return (retval);
 202 }
 203
 204 #define I2C_SETSDA(sc,dev,val) do {                     \
 205         IICBB_SETSDA(device_get_parent(dev), val);      \
 206         DELAY(sc->udelay);                              \
 207         } while (0)
 208
 209 #define I2C_SETSCL(dev,val) do {                        \
 210         iicbb_setscl(dev, val, 100);                    \
 211         } while (0)
 212
 213 #define I2C_SET(sc,dev,ctrl,data) do {                  \
 214         I2C_SETSCL(dev, ctrl);                          \
 215         I2C_SETSDA(sc, dev, data);                      \
 216         } while (0)
 217
 218 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
 219
 220 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
 221
 222 static int i2c_debug = 0;
 223 #define I2C_DEBUG(x)    do {                                    \
 224                                 if (i2c_debug) (x);             \
 225                         } while (0)
 226
 227 #define I2C_LOG(format,args...) do {                            \
 228                                         printf(format, args);   \
 229                                 } while (0)
 230
 231 static void
 232 iicbb_setscl(device_t dev, int val, int timeout)
 233 {
 234         struct iicbb_softc *sc = device_get_softc(dev);
 235         int k = 0;
 236
 237         IICBB_SETSCL(device_get_parent(dev), val);
 238         DELAY(sc->udelay);
 239
 240         while (val && !I2C_GETSCL(dev) && k++ < timeout) {
 241                 IICBB_SETSCL(device_get_parent(dev), val);
 242                 DELAY(sc->udelay);
 243         }
 244
 245         return;
 246 }
 247
 248 static void
 249 iicbb_one(device_t dev, int timeout)
 250 {
 251         struct iicbb_softc *sc = device_get_softc(dev);
 252
 253         I2C_SET(sc,dev,0,1);
 254         I2C_SET(sc,dev,1,1);
 255         I2C_SET(sc,dev,0,1);
 256         return;
 257 }
 258
 259 static void
 260 iicbb_zero(device_t dev, int timeout)
 261 {
 262         struct iicbb_softc *sc = device_get_softc(dev);
 263
 264         I2C_SET(sc,dev,0,0);
 265         I2C_SET(sc,dev,1,0);
 266         I2C_SET(sc,dev,0,0);
 267         return;
 268 }
 269
 270 /*
 271  * Waiting for ACKNOWLEDGE.
 272  *
 273  * When a chip is being addressed or has received data it will issue an
 274  * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
 275  * (set it to high level) and then release the CLOCK line.
 276  * Now it must wait for the SLAVE to pull the DATA line low.
 277  * Actually on the bus this looks like a START condition so nothing happens
 278  * because of the fact that the IC's that have not been addressed are doing
 279  * nothing.
 280  *
 281  * When the SLAVE has pulled this line low the MASTER will take the CLOCK
 282  * line low and then the SLAVE will release the SDA (data) line.
 283  */
 284 static int
 285 iicbb_ack(device_t dev, int timeout)
 286 {
 287         struct iicbb_softc *sc = device_get_softc(dev);
 288         int noack;
 289         int k = 0;
 290
 291         I2C_SET(sc,dev,0,1);
 292         I2C_SET(sc,dev,1,1);
 293         do {
 294                 noack = I2C_GETSDA(dev);
 295                 if (!noack)
 296                         break;
 297                 DELAY(1);
 298                 k++;
 299         } while (k < timeout);
 300
 301         I2C_SET(sc,dev,0,1);
 302         I2C_DEBUG(printf("%c ",noack?'-':'+'));
 303
 304         return (noack);
 305 }
 306
 307 static void
 308 iicbb_sendbyte(device_t dev, u_char data, int timeout)
 309 {
 310         int i;
 311
 312         for (i=7; i>=0; i--) {
 313                 if (data&(1<<i)) {
 314                         iicbb_one(dev, timeout);
 315                 } else {
 316                         iicbb_zero(dev, timeout);
 317                 }
 318         }
 319         I2C_DEBUG(printf("w%02x",(int)data));
 320         return;
 321 }
 322
 323 static u_char
 324 iicbb_readbyte(device_t dev, int last, int timeout)
 325 {
 326         struct iicbb_softc *sc = device_get_softc(dev);
 327         int i;
 328         unsigned char data=0;
 329
 330         I2C_SET(sc,dev,0,1);
 331         for (i=7; i>=0; i--)
 332         {
 333                 I2C_SET(sc,dev,1,1);
 334                 if (I2C_GETSDA(dev))
 335                         data |= (1<<i);
 336                 I2C_SET(sc,dev,0,1);
 337         }
 338         if (last) {
 339                 iicbb_one(dev, timeout);
 340         } else {
 341                 iicbb_zero(dev, timeout);
 342         }
 343         I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
 344         return data;
 345 }
 346
 347 static int
 348 iicbb_callback(device_t dev, int index, caddr_t data)
 349 {
 350         return (IICBB_CALLBACK(device_get_parent(dev), index, data));
 351 }
 352
 353 static int
 354 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
 355 {
 356         return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
 357 }
 358
 359 static int
 360 iicbb_start(device_t dev, u_char slave, int timeout)
 361 {
 362         struct iicbb_softc *sc = device_get_softc(dev);
 363         int error;
 364
 365         I2C_DEBUG(printf("<"));
 366
 367         I2C_SET(sc,dev,1,1);
 368         I2C_SET(sc,dev,1,0);
 369         I2C_SET(sc,dev,0,0);
 370
 371         /* send address */
 372         iicbb_sendbyte(dev, slave, timeout);
 373
 374         /* check for ack */
 375         if (iicbb_ack(dev, timeout)) {
 376                 error = IIC_ENOACK;
 377                 goto error;
 378         }
 379
 380         return(0);
 381
 382 error:
 383         iicbb_stop(dev);
 384         return (error);
 385 }
 386
 387 static int
 388 iicbb_stop(device_t dev)
 389 {
 390         struct iicbb_softc *sc = device_get_softc(dev);
 391
 392         I2C_SET(sc,dev,0,0);
 393         I2C_SET(sc,dev,1,0);
 394         I2C_SET(sc,dev,1,1);
 395         I2C_DEBUG(printf(">"));
 396         I2C_DEBUG(printf("\n"));
 397         return (0);
 398 }
 399
 400 static int
 401 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
 402 {
 403         int bytes, error = 0;
 404
 405         bytes = 0;
 406         while (len) {
 407                 /* send byte */
 408                 iicbb_sendbyte(dev,(u_char)*buf++, timeout);
 409
 410                 /* check for ack */
 411                 if (iicbb_ack(dev, timeout)) {
 412                         error = IIC_ENOACK;
 413                         goto error;
 414                 }
 415                 bytes ++;
 416                 len --;
 417         }
 418
 419 error:
 420         *sent = bytes;
 421         return (error);
 422 }
 423
 424 static int
 425 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
 426 {
 427         int bytes;
 428
 429         bytes = 0;
 430         while (len) {
 431                 /* XXX should insert delay here */
 432                 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
 433
 434                 bytes ++;
 435                 len --;
 436         }
 437
 438         *read = bytes;
 439         return (0);
 440 }
 441
 442 static int
 443 iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
 444 {
 445         int error;
 446
 447         error = IICBB_PRE_XFER(device_get_parent(dev));
 448         if (error)
 449                 return (error);
 450
 451         error = iicbus_transfer_gen(dev, msgs, nmsgs);
 452
 453         IICBB_POST_XFER(device_get_parent(dev));
 454         return (error);
 455 }
 456
 457 DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0);
 458
 459 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
 460 MODULE_VERSION(iicbb, IICBB_MODVER);