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