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_probe(device_t);
  67 static int iicbb_attach(device_t);
  68 static int iicbb_detach(device_t);
  69 static int iicbb_print_child(device_t, 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, 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
  78 static device_method_t iicbb_methods[] = {
  79         /* device interface */
  80         DEVMETHOD(device_probe,         iicbb_probe),
  81         DEVMETHOD(device_attach,        iicbb_attach),
  82         DEVMETHOD(device_detach,        iicbb_detach),
  83
  84         /* bus interface */
  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
  96         { 0, 0 }
  97 };
  98
  99 driver_t iicbb_driver = {
 100         "iicbb",
 101         iicbb_methods,
 102         sizeof(struct iicbb_softc),
 103 };
 104
 105 devclass_t iicbb_devclass;
 106
 107 static int iicbb_probe(device_t dev)
 108 {
 109         device_set_desc(dev, "I2C bit-banging driver");
 110
 111         return (0);
 112 }
 113
 114 static int iicbb_attach(device_t dev)
 115 {
 116         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 117
 118         bzero(sc, sizeof(struct iicbb_softc));
 119
 120         sc->iicbus = device_add_child(dev, "iicbus", -1);
 121
 122         if (!sc->iicbus)
 123                 return (ENXIO);
 124
 125         bus_generic_attach(dev);
 126
 127         return (0);
 128 }
 129
 130 static int iicbb_detach(device_t dev)
 131 {
 132         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 133
 134         if (sc->iicbus) {
 135                 bus_generic_detach(dev);
 136                 device_delete_child(dev, sc->iicbus);
 137         }
 138
 139         return (0);
 140 }
 141
 142 static int
 143 iicbb_print_child(device_t bus, device_t dev)
 144 {
 145         int error;
 146         int retval = 0;
 147         u_char oldaddr;
 148
 149         retval += bus_print_child_header(bus, dev);
 150         /* retrieve the interface I2C address */
 151         error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
 152         if (error == IIC_ENOADDR) {
 153                 retval += printf(" on %s master-only\n",
 154                                  device_get_nameunit(bus));
 155         } else {
 156                 /* restore the address */
 157                 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
 158
 159                 retval += printf(" on %s addr 0x%x\n",
 160                                  device_get_nameunit(bus), oldaddr & 0xff);
 161         }
 162
 163         return (retval);
 164 }
 165
 166 #define IIC_DELAY       10
 167
 168 #define I2C_SETSDA(dev,val) do {                        \
 169         IICBB_SETSDA(device_get_parent(dev), val);      \
 170         DELAY(IIC_DELAY);                               \
 171         } while (0)
 172
 173 #define I2C_SETSCL(dev,val) do {                        \
 174         iicbb_setscl(dev, val, 100);                    \
 175         } while (0)
 176
 177 #define I2C_SET(dev,ctrl,data) do {                     \
 178         I2C_SETSCL(dev, ctrl);                          \
 179         I2C_SETSDA(dev, data);                          \
 180         } while (0)
 181
 182 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
 183
 184 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
 185
 186 static int i2c_debug = 0;
 187 #define I2C_DEBUG(x)    do {                                    \
 188                                 if (i2c_debug) (x);             \
 189                         } while (0)
 190
 191 #define I2C_LOG(format,args...) do {                            \
 192                                         printf(format, args);   \
 193                                 } while (0)
 194
 195 static void iicbb_setscl(device_t dev, int val, int timeout)
 196 {
 197         int k = 0;
 198
 199         IICBB_SETSCL(device_get_parent(dev), val);
 200         DELAY(IIC_DELAY);
 201
 202         while (val && !I2C_GETSCL(dev) && k++ < timeout) {
 203                 IICBB_SETSCL(device_get_parent(dev), val);
 204                 DELAY(IIC_DELAY);
 205         }
 206
 207         return;
 208 }
 209
 210 static void iicbb_one(device_t dev, int timeout)
 211 {
 212         I2C_SET(dev,0,1);
 213         I2C_SET(dev,1,1);
 214         I2C_SET(dev,0,1);
 215         return;
 216 }
 217
 218 static void iicbb_zero(device_t dev, int timeout)
 219 {
 220         I2C_SET(dev,0,0);
 221         I2C_SET(dev,1,0);
 222         I2C_SET(dev,0,0);
 223         return;
 224 }
 225
 226 /*
 227  * Waiting for ACKNOWLEDGE.
 228  *
 229  * When a chip is being addressed or has received data it will issue an
 230  * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
 231  * (set it to high level) and then release the CLOCK line.
 232  * Now it must wait for the SLAVE to pull the DATA line low.
 233  * Actually on the bus this looks like a START condition so nothing happens
 234  * because of the fact that the IC's that have not been addressed are doing
 235  * nothing.
 236  *
 237  * When the SLAVE has pulled this line low the MASTER will take the CLOCK
 238  * line low and then the SLAVE will release the SDA (data) line.
 239  */
 240 static int iicbb_ack(device_t dev, int timeout)
 241 {
 242         int noack;
 243         int k = 0;
 244
 245         I2C_SET(dev,0,1);
 246         I2C_SET(dev,1,1);
 247         do {
 248                 noack = I2C_GETSDA(dev);
 249                 if (!noack)
 250                         break;
 251                 DELAY(10);
 252                 k += 10;
 253         } while (k < timeout);
 254
 255         I2C_SET(dev,0,1);
 256         I2C_DEBUG(printf("%c ",noack?'-':'+'));
 257
 258         return (noack);
 259 }
 260
 261 static void iicbb_sendbyte(device_t dev, u_char data, int timeout)
 262 {
 263         int i;
 264
 265         for (i=7; i>=0; i--) {
 266                 if (data&(1<<i)) {
 267                         iicbb_one(dev, timeout);
 268                 } else {
 269                         iicbb_zero(dev, timeout);
 270                 }
 271         }
 272         I2C_DEBUG(printf("w%02x",(int)data));
 273         return;
 274 }
 275
 276 static u_char iicbb_readbyte(device_t dev, int last, int timeout)
 277 {
 278         int i;
 279         unsigned char data=0;
 280
 281         I2C_SET(dev,0,1);
 282         for (i=7; i>=0; i--)
 283         {
 284                 I2C_SET(dev,1,1);
 285                 if (I2C_GETSDA(dev))
 286                         data |= (1<<i);
 287                 I2C_SET(dev,0,1);
 288         }
 289         if (last) {
 290                 iicbb_one(dev, timeout);
 291         } else {
 292                 iicbb_zero(dev, timeout);
 293         }
 294         I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
 295         return data;
 296 }
 297
 298 static int iicbb_callback(device_t dev, int index, caddr_t data)
 299 {
 300         return (IICBB_CALLBACK(device_get_parent(dev), index, data));
 301 }
 302
 303 static int iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
 304 {
 305         return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
 306 }
 307
 308 static int iicbb_start(device_t dev, u_char slave, int timeout)
 309 {
 310         int error;
 311
 312         I2C_DEBUG(printf("<"));
 313
 314         I2C_SET(dev,1,1);
 315         I2C_SET(dev,1,0);
 316         I2C_SET(dev,0,0);
 317
 318         /* send address */
 319         iicbb_sendbyte(dev, slave, timeout);
 320
 321         /* check for ack */
 322         if (iicbb_ack(dev, timeout)) {
 323                 error = IIC_ENOACK;
 324                 goto error;
 325         }
 326
 327         return(0);
 328
 329 error:
 330         iicbb_stop(dev);
 331         return (error);
 332 }
 333
 334 static int iicbb_stop(device_t dev)
 335 {
 336         I2C_SET(dev,0,0);
 337         I2C_SET(dev,1,0);
 338         I2C_SET(dev,1,1);
 339         I2C_DEBUG(printf(">"));
 340         return (0);
 341 }
 342
 343 static int iicbb_write(device_t dev, char * buf, int len, int *sent,
 344                         int timeout)
 345 {
 346         int bytes, error = 0;
 347
 348         bytes = 0;
 349         while (len) {
 350                 /* send byte */
 351                 iicbb_sendbyte(dev,(u_char)*buf++, timeout);
 352
 353                 /* check for ack */
 354                 if (iicbb_ack(dev, timeout)) {
 355                         error = IIC_ENOACK;
 356                         goto error;
 357                 }
 358                 bytes ++;
 359                 len --;
 360         }
 361
 362 error:
 363         *sent = bytes;
 364         return (error);
 365 }
 366
 367 static int iicbb_read(device_t dev, char * buf, int len, int *read,
 368                         int last, int delay)
 369 {
 370         int bytes;
 371
 372         bytes = 0;
 373         while (len) {
 374                 /* XXX should insert delay here */
 375                 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
 376
 377                 bytes ++;
 378                 len --;
 379         }
 380
 381         *read = bytes;
 382         return (0);
 383 }
 384
 385 DRIVER_MODULE(iicbb, bktr, iicbb_driver, iicbb_devclass, 0, 0);
 386 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
 387 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0);
 388
 389 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
 390 MODULE_VERSION(iicbb, IICBB_MODVER);