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: head/sys/dev/iicbus/iicbb.c 232365 2012-03-01 20:58:20Z kan $
  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         int udelay;             /* signal toggle delay in usec */
  63 };
  64
  65 static int iicbb_attach(device_t);
  66 static void iicbb_child_detached(device_t, device_t);
  67 static int iicbb_detach(device_t);
  68 static int iicbb_print_child(device_t, device_t);
  69 static int iicbb_probe(device_t);
  70
  71 static int iicbb_callback(device_t, int, caddr_t);
  72 static int iicbb_start(device_t, u_char, int);
  73 static int iicbb_stop(device_t);
  74 static int iicbb_write(device_t, const char *, int, int *, int);
  75 static int iicbb_read(device_t, char *, int, int *, int, int);
  76 static int iicbb_reset(device_t, u_char, u_char, u_char *);
  77 static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs);
  78
  79 static device_method_t iicbb_methods[] = {
  80         /* device interface */
  81         DEVMETHOD(device_probe,         iicbb_probe),
  82         DEVMETHOD(device_attach,        iicbb_attach),
  83         DEVMETHOD(device_detach,        iicbb_detach),
  84
  85         /* bus interface */
  86         DEVMETHOD(bus_child_detached,   iicbb_child_detached),
  87         DEVMETHOD(bus_print_child,      iicbb_print_child),
  88
  89         /* iicbus interface */
  90         DEVMETHOD(iicbus_callback,      iicbb_callback),
  91         DEVMETHOD(iicbus_start,         iicbb_start),
  92         DEVMETHOD(iicbus_repeated_start, iicbb_start),
  93         DEVMETHOD(iicbus_stop,          iicbb_stop),
  94         DEVMETHOD(iicbus_write,         iicbb_write),
  95         DEVMETHOD(iicbus_read,          iicbb_read),
  96         DEVMETHOD(iicbus_reset,         iicbb_reset),
  97         DEVMETHOD(iicbus_transfer,      iicbb_transfer),
  98
  99         DEVMETHOD_END
 100 };
 101
 102 driver_t iicbb_driver = {
 103         "iicbb",
 104         iicbb_methods,
 105         sizeof(struct iicbb_softc),
 106 };
 107
 108 devclass_t iicbb_devclass;
 109
 110 static int
 111 iicbb_probe(device_t dev)
 112 {
 113         device_set_desc(dev, "I2C bit-banging driver");
 114
 115         return (0);
 116 }
 117
 118 static int
 119 iicbb_attach(device_t dev)
 120 {
 121         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 122
 123         sc->iicbus = device_add_child(dev, "iicbus", -1);
 124         if (!sc->iicbus)
 125                 return (ENXIO);
 126         sc->udelay = 10;                /* 10 uS default */
 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 += kprintf(" 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 += kprintf(" on %s addr 0x%x\n",
 182                                  device_get_nameunit(bus), oldaddr & 0xff);
 183         }
 184
 185         return (retval);
 186 }
 187
 188 #define I2C_SETSDA(sc,dev,val) do {                     \
 189         IICBB_SETSDA(device_get_parent(dev), val);      \
 190         DELAY(sc->udelay);                              \
 191         } while (0)
 192
 193 #define I2C_SETSCL(dev,val) do {                        \
 194         iicbb_setscl(dev, val, 100);                    \
 195         } while (0)
 196
 197 #define I2C_SET(sc,dev,ctrl,data) do {                  \
 198         I2C_SETSCL(dev, ctrl);                          \
 199         I2C_SETSDA(sc, dev, data);                      \
 200         } while (0)
 201
 202 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
 203
 204 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
 205
 206 static int i2c_debug = 0;
 207 #define I2C_DEBUG(x)    do {                                    \
 208                                 if (i2c_debug) (x);             \
 209                         } while (0)
 210
 211 #define I2C_LOG(format,args...) do {                            \
 212                                         kprintf(format, args);  \
 213                                 } while (0)
 214
 215 static void
 216 iicbb_setscl(device_t dev, int val, int timeout)
 217 {
 218         struct iicbb_softc *sc = device_get_softc(dev);
 219         int k = 0;
 220
 221         IICBB_SETSCL(device_get_parent(dev), val);
 222         DELAY(sc->udelay);
 223
 224         while (val && !I2C_GETSCL(dev) && k++ < timeout) {
 225                 IICBB_SETSCL(device_get_parent(dev), val);
 226                 DELAY(sc->udelay);
 227         }
 228
 229         return;
 230 }
 231
 232 static void
 233 iicbb_one(device_t dev, int timeout)
 234 {
 235         struct iicbb_softc *sc = device_get_softc(dev);
 236
 237         I2C_SET(sc,dev,0,1);
 238         I2C_SET(sc,dev,1,1);
 239         I2C_SET(sc,dev,0,1);
 240         return;
 241 }
 242
 243 static void
 244 iicbb_zero(device_t dev, int timeout)
 245 {
 246         struct iicbb_softc *sc = device_get_softc(dev);
 247
 248         I2C_SET(sc,dev,0,0);
 249         I2C_SET(sc,dev,1,0);
 250         I2C_SET(sc,dev,0,0);
 251         return;
 252 }
 253
 254 /*
 255  * Waiting for ACKNOWLEDGE.
 256  *
 257  * When a chip is being addressed or has received data it will issue an
 258  * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
 259  * (set it to high level) and then release the CLOCK line.
 260  * Now it must wait for the SLAVE to pull the DATA line low.
 261  * Actually on the bus this looks like a START condition so nothing happens
 262  * because of the fact that the IC's that have not been addressed are doing
 263  * nothing.
 264  *
 265  * When the SLAVE has pulled this line low the MASTER will take the CLOCK
 266  * line low and then the SLAVE will release the SDA (data) line.
 267  */
 268 static int
 269 iicbb_ack(device_t dev, int timeout)
 270 {
 271         struct iicbb_softc *sc = device_get_softc(dev);
 272         int noack;
 273         int k = 0;
 274
 275         I2C_SET(sc,dev,0,1);
 276         I2C_SET(sc,dev,1,1);
 277         do {
 278                 noack = I2C_GETSDA(dev);
 279                 if (!noack)
 280                         break;
 281                 DELAY(1);
 282                 k++;
 283         } while (k < timeout);
 284
 285         I2C_SET(sc,dev,0,1);
 286         I2C_DEBUG(kprintf("%c ",noack?'-':'+'));
 287
 288         return (noack);
 289 }
 290
 291 static void
 292 iicbb_sendbyte(device_t dev, u_char data, int timeout)
 293 {
 294         int i;
 295
 296         for (i=7; i>=0; i--) {
 297                 if (data&(1<<i)) {
 298                         iicbb_one(dev, timeout);
 299                 } else {
 300                         iicbb_zero(dev, timeout);
 301                 }
 302         }
 303         I2C_DEBUG(kprintf("w%02x",(int)data));
 304         return;
 305 }
 306
 307 static u_char
 308 iicbb_readbyte(device_t dev, int last, int timeout)
 309 {
 310         struct iicbb_softc *sc = device_get_softc(dev);
 311         int i;
 312         unsigned char data=0;
 313
 314         I2C_SET(sc,dev,0,1);
 315         for (i=7; i>=0; i--)
 316         {
 317                 I2C_SET(sc,dev,1,1);
 318                 if (I2C_GETSDA(dev))
 319                         data |= (1<<i);
 320                 I2C_SET(sc,dev,0,1);
 321         }
 322         if (last) {
 323                 iicbb_one(dev, timeout);
 324         } else {
 325                 iicbb_zero(dev, timeout);
 326         }
 327         I2C_DEBUG(kprintf("r%02x%c ",(int)data,last?'-':'+'));
 328         return data;
 329 }
 330
 331 static int
 332 iicbb_callback(device_t dev, int index, caddr_t data)
 333 {
 334         return (IICBB_CALLBACK(device_get_parent(dev), index, data));
 335 }
 336
 337 static int
 338 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
 339 {
 340         return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
 341 }
 342
 343 static int
 344 iicbb_start(device_t dev, u_char slave, int timeout)
 345 {
 346         struct iicbb_softc *sc = device_get_softc(dev);
 347         int error;
 348
 349         I2C_DEBUG(kprintf("<"));
 350
 351         I2C_SET(sc,dev,1,1);
 352         I2C_SET(sc,dev,1,0);
 353         I2C_SET(sc,dev,0,0);
 354
 355         /* send address */
 356         iicbb_sendbyte(dev, slave, timeout);
 357
 358         /* check for ack */
 359         if (iicbb_ack(dev, timeout)) {
 360                 error = IIC_ENOACK;
 361                 goto error;
 362         }
 363
 364         return(0);
 365
 366 error:
 367         iicbb_stop(dev);
 368         return (error);
 369 }
 370
 371 static int
 372 iicbb_stop(device_t dev)
 373 {
 374         struct iicbb_softc *sc = device_get_softc(dev);
 375
 376         I2C_SET(sc,dev,0,0);
 377         I2C_SET(sc,dev,1,0);
 378         I2C_SET(sc,dev,1,1);
 379         I2C_DEBUG(kprintf(">"));
 380         I2C_DEBUG(kprintf("\n"));
 381         return (0);
 382 }
 383
 384 static int
 385 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
 386 {
 387         int bytes, error = 0;
 388
 389         bytes = 0;
 390         while (len) {
 391                 /* send byte */
 392                 iicbb_sendbyte(dev,(u_char)*buf++, timeout);
 393
 394                 /* check for ack */
 395                 if (iicbb_ack(dev, timeout)) {
 396                         error = IIC_ENOACK;
 397                         goto error;
 398                 }
 399                 bytes ++;
 400                 len --;
 401         }
 402
 403 error:
 404         *sent = bytes;
 405         return (error);
 406 }
 407
 408 static int
 409 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
 410 {
 411         int bytes;
 412
 413         bytes = 0;
 414         while (len) {
 415                 /* XXX should insert delay here */
 416                 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
 417
 418                 bytes ++;
 419                 len --;
 420         }
 421
 422         *read = bytes;
 423         return (0);
 424 }
 425
 426 static int
 427 iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
 428 {
 429         int error;
 430
 431         error = IICBB_PRE_XFER(device_get_parent(dev));
 432         if (error)
 433                 return (error);
 434
 435         error = iicbus_transfer_gen(dev, msgs, nmsgs);
 436
 437         IICBB_POST_XFER(device_get_parent(dev));
 438         return (error);
 439 }
 440
 441 DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, NULL, NULL);
 442 DRIVER_MODULE(iicbb, cxm_iic, iicbb_driver, iicbb_devclass, NULL, NULL);
 443 DRIVER_MODULE(iicbb, intel_iic, iicbb_driver, iicbb_devclass, NULL, NULL);
 444 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, NULL, NULL);
 445 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, NULL, NULL);
 446
 447 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
 448 MODULE_VERSION(iicbb, IICBB_MODVER);