sys/bus/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  * $FreeBSD: src/sys/dev/iicbus/iicbb.c,v 1.21 2009/02/10 22:50:23 imp Exp $
  27  */
  28
  29 /*
  30  * Generic I2C bit-banging code
  31  *
  32  * Example:
  33  *
  34  *      iicbus
  35  *       /  \
  36  *    iicbb pcf
  37  *     |  \
  38  *   bti2c lpbb
  39  *
  40  * From Linux I2C generic interface
  41  * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
  42  *
  43  */
  44
  45 #include <sys/param.h>
  46 #include <sys/kernel.h>
  47 #include <sys/systm.h>
  48 #include <sys/module.h>
  49 #include <sys/bus.h>
  50 #include <sys/uio.h>
  51
  52 #include <bus/iicbus/iiconf.h>
  53 #include <bus/iicbus/iicbus.h>
  54
  55 #include <bus/smbus/smbconf.h>
  56
  57 #include "iicbus_if.h"
  58 #include "iicbb_if.h"
  59
  60 struct iicbb_softc {
  61         device_t iicbus;
  62 };
  63
  64 static int iicbb_attach(device_t);
  65 static void iicbb_child_detached(device_t, device_t);
  66 static int iicbb_detach(device_t);
  67 static int iicbb_print_child(device_t, device_t);
  68 static int iicbb_probe(device_t);
  69
  70 static int iicbb_callback(device_t, int, caddr_t);
  71 static int iicbb_start(device_t, u_char, int);
  72 static int iicbb_stop(device_t);
  73 static int iicbb_write(device_t, const char *, int, int *, int);
  74 static int iicbb_read(device_t, char *, int, int *, int, int);
  75 static int iicbb_reset(device_t, u_char, u_char, u_char *);
  76
  77 static device_method_t iicbb_methods[] = {
  78         /* device interface */
  79         DEVMETHOD(device_probe,         iicbb_probe),
  80         DEVMETHOD(device_attach,        iicbb_attach),
  81         DEVMETHOD(device_detach,        iicbb_detach),
  82
  83         /* bus interface */
  84         DEVMETHOD(bus_child_detached,   iicbb_child_detached),
  85         DEVMETHOD(bus_print_child,      iicbb_print_child),
  86
  87         /* iicbus interface */
  88         DEVMETHOD(iicbus_callback,      iicbb_callback),
  89         DEVMETHOD(iicbus_start,         iicbb_start),
  90         DEVMETHOD(iicbus_repeated_start, iicbb_start),
  91         DEVMETHOD(iicbus_stop,          iicbb_stop),
  92         DEVMETHOD(iicbus_write,         iicbb_write),
  93         DEVMETHOD(iicbus_read,          iicbb_read),
  94         DEVMETHOD(iicbus_reset,         iicbb_reset),
  95         DEVMETHOD(iicbus_transfer,      iicbus_transfer_gen),
  96
  97         { 0, 0 }
  98 };
  99
 100 driver_t iicbb_driver = {
 101         "iicbb",
 102         iicbb_methods,
 103         sizeof(struct iicbb_softc),
 104 };
 105
 106 devclass_t iicbb_devclass;
 107
 108 static int
 109 iicbb_probe(device_t dev)
 110 {
 111         device_set_desc(dev, "I2C bit-banging driver");
 112
 113         return (0);
 114 }
 115
 116 static int
 117 iicbb_attach(device_t dev)
 118 {
 119         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 120
 121         sc->iicbus = device_add_child(dev, "iicbus", -1);
 122         if (!sc->iicbus)
 123                 return (ENXIO);
 124         bus_generic_attach(dev);
 125
 126         return (0);
 127 }
 128
 129 static int
 130 iicbb_detach(device_t dev)
 131 {
 132         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 133         device_t child;
 134
 135         /*
 136          * We need to save child because the detach indirectly causes
 137          * sc->iicbus to be zeroed.  Since we added the device
 138          * unconditionally in iicbb_attach, we need to make sure we
 139          * delete it here.  See iicbb_child_detached.  We need that
 140          * callback in case newbus detached our children w/o detaching
 141          * us (say iicbus is a module and unloaded w/o iicbb being
 142          * unloaded).
 143          */
 144         child = sc->iicbus;
 145         bus_generic_detach(dev);
 146         if (child)
 147                 device_delete_child(dev, child);
 148
 149         return (0);
 150 }
 151
 152 static void
 153 iicbb_child_detached( device_t dev, device_t child )
 154 {
 155         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 156
 157         if (child == sc->iicbus)
 158                 sc->iicbus = NULL;
 159 }
 160
 161 static int
 162 iicbb_print_child(device_t bus, device_t dev)
 163 {
 164         int error;
 165         int retval = 0;
 166         u_char oldaddr;
 167
 168         retval += bus_print_child_header(bus, dev);
 169         /* retrieve the interface I2C address */
 170         error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
 171         if (error == IIC_ENOADDR) {
 172                 retval += kprintf(" on %s master-only\n",
 173                                  device_get_nameunit(bus));
 174         } else {
 175                 /* restore the address */
 176                 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
 177
 178                 retval += kprintf(" on %s addr 0x%x\n",
 179                                  device_get_nameunit(bus), oldaddr & 0xff);
 180         }
 181
 182         return (retval);
 183 }
 184
 185 #define IIC_DELAY       10
 186
 187 #define I2C_SETSDA(dev,val) do {                        \
 188         IICBB_SETSDA(device_get_parent(dev), val);      \
 189         DELAY(IIC_DELAY);                               \
 190         } while (0)
 191
 192 #define I2C_SETSCL(dev,val) do {                        \
 193         iicbb_setscl(dev, val, 100);                    \
 194         } while (0)
 195
 196 #define I2C_SET(dev,ctrl,data) do {                     \
 197         I2C_SETSCL(dev, ctrl);                          \
 198         I2C_SETSDA(dev, data);                          \
 199         } while (0)
 200
 201 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
 202
 203 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
 204
 205 static int i2c_debug = 0;
 206 #define I2C_DEBUG(x)    do {                                    \
 207                                 if (i2c_debug) (x);             \
 208                         } while (0)
 209
 210 #define I2C_LOG(format,args...) do {                            \
 211                                         kprintf(format, args);  \
 212                                 } while (0)
 213
 214 static void
 215 iicbb_setscl(device_t dev, int val, int timeout)
 216 {
 217         int k = 0;
 218
 219         IICBB_SETSCL(device_get_parent(dev), val);
 220         DELAY(IIC_DELAY);
 221
 222         while (val && !I2C_GETSCL(dev) && k++ < timeout) {
 223                 IICBB_SETSCL(device_get_parent(dev), val);
 224                 DELAY(IIC_DELAY);
 225         }
 226
 227         return;
 228 }
 229
 230 static void
 231 iicbb_one(device_t dev, int timeout)
 232 {
 233         I2C_SET(dev,0,1);
 234         I2C_SET(dev,1,1);
 235         I2C_SET(dev,0,1);
 236         return;
 237 }
 238
 239 static void
 240 iicbb_zero(device_t dev, int timeout)
 241 {
 242         I2C_SET(dev,0,0);
 243         I2C_SET(dev,1,0);
 244         I2C_SET(dev,0,0);
 245         return;
 246 }
 247
 248 /*
 249  * Waiting for ACKNOWLEDGE.
 250  *
 251  * When a chip is being addressed or has received data it will issue an
 252  * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
 253  * (set it to high level) and then release the CLOCK line.
 254  * Now it must wait for the SLAVE to pull the DATA line low.
 255  * Actually on the bus this looks like a START condition so nothing happens
 256  * because of the fact that the IC's that have not been addressed are doing
 257  * nothing.
 258  *
 259  * When the SLAVE has pulled this line low the MASTER will take the CLOCK
 260  * line low and then the SLAVE will release the SDA (data) line.
 261  */
 262 static int
 263 iicbb_ack(device_t dev, int timeout)
 264 {
 265         int noack;
 266         int k = 0;
 267
 268         I2C_SET(dev,0,1);
 269         I2C_SET(dev,1,1);
 270         do {
 271                 noack = I2C_GETSDA(dev);
 272                 if (!noack)
 273                         break;
 274                 DELAY(10);
 275                 k += 10;
 276         } while (k < timeout);
 277
 278         I2C_SET(dev,0,1);
 279         I2C_DEBUG(kprintf("%c ",noack?'-':'+'));
 280
 281         return (noack);
 282 }
 283
 284 static void
 285 iicbb_sendbyte(device_t dev, u_char data, int timeout)
 286 {
 287         int i;
 288
 289         for (i=7; i>=0; i--) {
 290                 if (data&(1<<i)) {
 291                         iicbb_one(dev, timeout);
 292                 } else {
 293                         iicbb_zero(dev, timeout);
 294                 }
 295         }
 296         I2C_DEBUG(kprintf("w%02x",(int)data));
 297         return;
 298 }
 299
 300 static u_char
 301 iicbb_readbyte(device_t dev, int last, int timeout)
 302 {
 303         int i;
 304         unsigned char data=0;
 305
 306         I2C_SET(dev,0,1);
 307         for (i=7; i>=0; i--)
 308         {
 309                 I2C_SET(dev,1,1);
 310                 if (I2C_GETSDA(dev))
 311                         data |= (1<<i);
 312                 I2C_SET(dev,0,1);
 313         }
 314         if (last) {
 315                 iicbb_one(dev, timeout);
 316         } else {
 317                 iicbb_zero(dev, timeout);
 318         }
 319         I2C_DEBUG(kprintf("r%02x%c ",(int)data,last?'-':'+'));
 320         return data;
 321 }
 322
 323 static int
 324 iicbb_callback(device_t dev, int index, caddr_t data)
 325 {
 326         return (IICBB_CALLBACK(device_get_parent(dev), index, data));
 327 }
 328
 329 static int
 330 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
 331 {
 332         return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
 333 }
 334
 335 static int
 336 iicbb_start(device_t dev, u_char slave, int timeout)
 337 {
 338         int error;
 339
 340         I2C_DEBUG(kprintf("<"));
 341
 342         I2C_SET(dev,1,1);
 343         I2C_SET(dev,1,0);
 344         I2C_SET(dev,0,0);
 345
 346         /* send address */
 347         iicbb_sendbyte(dev, slave, timeout);
 348
 349         /* check for ack */
 350         if (iicbb_ack(dev, timeout)) {
 351                 error = IIC_ENOACK;
 352                 goto error;
 353         }
 354
 355         return(0);
 356
 357 error:
 358         iicbb_stop(dev);
 359         return (error);
 360 }
 361
 362 static int
 363 iicbb_stop(device_t dev)
 364 {
 365         I2C_SET(dev,0,0);
 366         I2C_SET(dev,1,0);
 367         I2C_SET(dev,1,1);
 368         I2C_DEBUG(kprintf(">"));
 369         return (0);
 370 }
 371
 372 static int
 373 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
 374 {
 375         int bytes, error = 0;
 376
 377         bytes = 0;
 378         while (len) {
 379                 /* send byte */
 380                 iicbb_sendbyte(dev,(u_char)*buf++, timeout);
 381
 382                 /* check for ack */
 383                 if (iicbb_ack(dev, timeout)) {
 384                         error = IIC_ENOACK;
 385                         goto error;
 386                 }
 387                 bytes ++;
 388                 len --;
 389         }
 390
 391 error:
 392         *sent = bytes;
 393         return (error);
 394 }
 395
 396 static int
 397 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
 398 {
 399         int bytes;
 400
 401         bytes = 0;
 402         while (len) {
 403                 /* XXX should insert delay here */
 404                 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
 405
 406                 bytes ++;
 407                 len --;
 408         }
 409
 410         *read = bytes;
 411         return (0);
 412 }
 413
 414 DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, NULL, NULL);
 415 DRIVER_MODULE(iicbb, cxm_iic, iicbb_driver, iicbb_devclass, NULL, NULL);
 416 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, NULL, NULL);
 417 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, NULL, NULL);
 418
 419 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
 420 MODULE_VERSION(iicbb, IICBB_MODVER);