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
 153         bus_generic_detach(dev);
 154         device_delete_children(dev);
 155
 156         return (0);
 157 }
 158
 159 #ifdef FDT
 160 static phandle_t
 161 iicbb_get_node(device_t bus, device_t dev)
 162 {
 163
 164         /* We only have one child, the I2C bus, which needs our own node. */
 165         return (ofw_bus_get_node(bus));
 166 }
 167 #endif
 168
 169 static void
 170 iicbb_child_detached( device_t dev, device_t child )
 171 {
 172         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 173
 174         if (child == sc->iicbus)
 175                 sc->iicbus = NULL;
 176 }
 177
 178 static int
 179 iicbb_print_child(device_t bus, device_t dev)
 180 {
 181         int error;
 182         int retval = 0;
 183         u_char oldaddr;
 184
 185         retval += bus_print_child_header(bus, dev);
 186         /* retrieve the interface I2C address */
 187         error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
 188         if (error == IIC_ENOADDR) {
 189                 retval += printf(" on %s master-only\n",
 190                                  device_get_nameunit(bus));
 191         } else {
 192                 /* restore the address */
 193                 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
 194
 195                 retval += printf(" on %s addr 0x%x\n",
 196                                  device_get_nameunit(bus), oldaddr & 0xff);
 197         }
 198
 199         return (retval);
 200 }
 201
 202 #define I2C_SETSDA(sc,dev,val) do {                     \
 203         IICBB_SETSDA(device_get_parent(dev), val);      \
 204         DELAY(sc->udelay);                              \
 205         } while (0)
 206
 207 #define I2C_SETSCL(dev,val) do {                        \
 208         iicbb_setscl(dev, val, 100);                    \
 209         } while (0)
 210
 211 #define I2C_SET(sc,dev,ctrl,data) do {                  \
 212         I2C_SETSCL(dev, ctrl);                          \
 213         I2C_SETSDA(sc, dev, data);                      \
 214         } while (0)
 215
 216 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
 217
 218 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
 219
 220 static int i2c_debug = 0;
 221 #define I2C_DEBUG(x)    do {                                    \
 222                                 if (i2c_debug) (x);             \
 223                         } while (0)
 224
 225 #define I2C_LOG(format,args...) do {                            \
 226                                         printf(format, args);   \
 227                                 } while (0)
 228
 229 static void
 230 iicbb_setscl(device_t dev, int val, int timeout)
 231 {
 232         struct iicbb_softc *sc = device_get_softc(dev);
 233         int k = 0;
 234
 235         IICBB_SETSCL(device_get_parent(dev), val);
 236         DELAY(sc->udelay);
 237
 238         while (val && !I2C_GETSCL(dev) && k++ < timeout) {
 239                 IICBB_SETSCL(device_get_parent(dev), val);
 240                 DELAY(sc->udelay);
 241         }
 242
 243         return;
 244 }
 245
 246 static void
 247 iicbb_one(device_t dev, int timeout)
 248 {
 249         struct iicbb_softc *sc = device_get_softc(dev);
 250
 251         I2C_SET(sc,dev,0,1);
 252         I2C_SET(sc,dev,1,1);
 253         I2C_SET(sc,dev,0,1);
 254         return;
 255 }
 256
 257 static void
 258 iicbb_zero(device_t dev, int timeout)
 259 {
 260         struct iicbb_softc *sc = device_get_softc(dev);
 261
 262         I2C_SET(sc,dev,0,0);
 263         I2C_SET(sc,dev,1,0);
 264         I2C_SET(sc,dev,0,0);
 265         return;
 266 }
 267
 268 /*
 269  * Waiting for ACKNOWLEDGE.
 270  *
 271  * When a chip is being addressed or has received data it will issue an
 272  * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
 273  * (set it to high level) and then release the CLOCK line.
 274  * Now it must wait for the SLAVE to pull the DATA line low.
 275  * Actually on the bus this looks like a START condition so nothing happens
 276  * because of the fact that the IC's that have not been addressed are doing
 277  * nothing.
 278  *
 279  * When the SLAVE has pulled this line low the MASTER will take the CLOCK
 280  * line low and then the SLAVE will release the SDA (data) line.
 281  */
 282 static int
 283 iicbb_ack(device_t dev, int timeout)
 284 {
 285         struct iicbb_softc *sc = device_get_softc(dev);
 286         int noack;
 287         int k = 0;
 288
 289         I2C_SET(sc,dev,0,1);
 290         I2C_SET(sc,dev,1,1);
 291         do {
 292                 noack = I2C_GETSDA(dev);
 293                 if (!noack)
 294                         break;
 295                 DELAY(1);
 296                 k++;
 297         } while (k < timeout);
 298
 299         I2C_SET(sc,dev,0,1);
 300         I2C_DEBUG(printf("%c ",noack?'-':'+'));
 301
 302         return (noack);
 303 }
 304
 305 static void
 306 iicbb_sendbyte(device_t dev, u_char data, int timeout)
 307 {
 308         int i;
 309
 310         for (i=7; i>=0; i--) {
 311                 if (data&(1<<i)) {
 312                         iicbb_one(dev, timeout);
 313                 } else {
 314                         iicbb_zero(dev, timeout);
 315                 }
 316         }
 317         I2C_DEBUG(printf("w%02x",(int)data));
 318         return;
 319 }
 320
 321 static u_char
 322 iicbb_readbyte(device_t dev, int last, int timeout)
 323 {
 324         struct iicbb_softc *sc = device_get_softc(dev);
 325         int i;
 326         unsigned char data=0;
 327
 328         I2C_SET(sc,dev,0,1);
 329         for (i=7; i>=0; i--)
 330         {
 331                 I2C_SET(sc,dev,1,1);
 332                 if (I2C_GETSDA(dev))
 333                         data |= (1<<i);
 334                 I2C_SET(sc,dev,0,1);
 335         }
 336         if (last) {
 337                 iicbb_one(dev, timeout);
 338         } else {
 339                 iicbb_zero(dev, timeout);
 340         }
 341         I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
 342         return data;
 343 }
 344
 345 static int
 346 iicbb_callback(device_t dev, int index, caddr_t data)
 347 {
 348         return (IICBB_CALLBACK(device_get_parent(dev), index, data));
 349 }
 350
 351 static int
 352 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
 353 {
 354         return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
 355 }
 356
 357 static int
 358 iicbb_start(device_t dev, u_char slave, int timeout)
 359 {
 360         struct iicbb_softc *sc = device_get_softc(dev);
 361         int error;
 362
 363         I2C_DEBUG(printf("<"));
 364
 365         I2C_SET(sc,dev,1,1);
 366         I2C_SET(sc,dev,1,0);
 367         I2C_SET(sc,dev,0,0);
 368
 369         /* send address */
 370         iicbb_sendbyte(dev, slave, timeout);
 371
 372         /* check for ack */
 373         if (iicbb_ack(dev, timeout)) {
 374                 error = IIC_ENOACK;
 375                 goto error;
 376         }
 377
 378         return(0);
 379
 380 error:
 381         iicbb_stop(dev);
 382         return (error);
 383 }
 384
 385 static int
 386 iicbb_stop(device_t dev)
 387 {
 388         struct iicbb_softc *sc = device_get_softc(dev);
 389
 390         I2C_SET(sc,dev,0,0);
 391         I2C_SET(sc,dev,1,0);
 392         I2C_SET(sc,dev,1,1);
 393         I2C_DEBUG(printf(">"));
 394         I2C_DEBUG(printf("\n"));
 395         return (0);
 396 }
 397
 398 static int
 399 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
 400 {
 401         int bytes, error = 0;
 402
 403         bytes = 0;
 404         while (len) {
 405                 /* send byte */
 406                 iicbb_sendbyte(dev,(u_char)*buf++, timeout);
 407
 408                 /* check for ack */
 409                 if (iicbb_ack(dev, timeout)) {
 410                         error = IIC_ENOACK;
 411                         goto error;
 412                 }
 413                 bytes ++;
 414                 len --;
 415         }
 416
 417 error:
 418         *sent = bytes;
 419         return (error);
 420 }
 421
 422 static int
 423 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
 424 {
 425         int bytes;
 426
 427         bytes = 0;
 428         while (len) {
 429                 /* XXX should insert delay here */
 430                 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
 431
 432                 bytes ++;
 433                 len --;
 434         }
 435
 436         *read = bytes;
 437         return (0);
 438 }
 439
 440 static int
 441 iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
 442 {
 443         int error;
 444
 445         error = IICBB_PRE_XFER(device_get_parent(dev));
 446         if (error)
 447                 return (error);
 448
 449         error = iicbus_transfer_gen(dev, msgs, nmsgs);
 450
 451         IICBB_POST_XFER(device_get_parent(dev));
 452         return (error);
 453 }
 454
 455 DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0);
 456
 457 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
 458 MODULE_VERSION(iicbb, IICBB_MODVER);