sys/bus/iicbus/iicbb.c

   1 /*-
   2  * Copyright (c) 1998 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 1.6.2.2 2002/04/19 05:52:12 nsouch Exp $
  27  * $DragonFly: src/sys/bus/iicbus/iicbb.c,v 1.5 2006/12/22 23:12:16 swildner Exp $
  28  *
  29  */
  30
  31 /*
  32  * Generic I2C bit-banging code
  33  *
  34  * Example:
  35  *
  36  *      iicbus
  37  *       /  \
  38  *    iicbb pcf
  39  *     |  \
  40  *   bti2c lpbb
  41  *
  42  * From Linux I2C generic interface
  43  * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
  44  *
  45  * TODO: port Peter's generic bit-banging code <dufault@hda.com>
  46  */
  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/conf.h>
  54 #include <sys/buf.h>
  55 #include <sys/uio.h>
  56 #include <sys/malloc.h>
  57
  58 #include <machine/clock.h>
  59
  60 #include "iiconf.h"
  61 #include "iicbus.h"
  62
  63 #include <bus/smbus/smbconf.h>
  64
  65 #include "iicbus_if.h"
  66 #include "iicbb_if.h"
  67
  68 struct iicbb_softc {
  69         device_t iicbus;
  70 };
  71
  72 static int iicbb_probe(device_t);
  73 static int iicbb_attach(device_t);
  74 static int iicbb_detach(device_t);
  75 static int iicbb_print_child(device_t, device_t);
  76
  77 static int iicbb_callback(device_t, int, caddr_t);
  78 static int iicbb_start(device_t, u_char, int);
  79 static int iicbb_stop(device_t);
  80 static int iicbb_write(device_t, char *, int, int *, int);
  81 static int iicbb_read(device_t, char *, int, int *, int, int);
  82 static int iicbb_reset(device_t, u_char, u_char, u_char *);
  83
  84 static device_method_t iicbb_methods[] = {
  85         /* device interface */
  86         DEVMETHOD(device_probe,         iicbb_probe),
  87         DEVMETHOD(device_attach,        iicbb_attach),
  88         DEVMETHOD(device_detach,        iicbb_detach),
  89
  90         /* bus interface */
  91         DEVMETHOD(bus_print_child,      iicbb_print_child),
  92
  93         /* iicbus interface */
  94         DEVMETHOD(iicbus_callback,      iicbb_callback),
  95         DEVMETHOD(iicbus_start,         iicbb_start),
  96         DEVMETHOD(iicbus_repeated_start, iicbb_start),
  97         DEVMETHOD(iicbus_stop,          iicbb_stop),
  98         DEVMETHOD(iicbus_write,         iicbb_write),
  99         DEVMETHOD(iicbus_read,          iicbb_read),
 100         DEVMETHOD(iicbus_reset,         iicbb_reset),
 101
 102         { 0, 0 }
 103 };
 104
 105 static driver_t iicbb_driver = {
 106         "iicbb",
 107         iicbb_methods,
 108         sizeof(struct iicbb_softc),
 109 };
 110
 111 static devclass_t iicbb_devclass;
 112
 113 static int
 114 iicbb_probe(device_t dev)
 115 {
 116         device_set_desc(dev, "I2C bit-banging driver");
 117
 118         return (0);
 119 }
 120
 121 static int
 122 iicbb_attach(device_t dev)
 123 {
 124         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 125
 126         bzero(sc, sizeof(struct iicbb_softc));
 127
 128         sc->iicbus = device_add_child(dev, "iicbus", -1);
 129
 130         if (!sc->iicbus)
 131                 return (ENXIO);
 132
 133         bus_generic_attach(dev);
 134
 135         return (0);
 136 }
 137
 138 static int
 139 iicbb_detach(device_t dev)
 140 {
 141         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 142
 143         if (sc->iicbus) {
 144                 bus_generic_detach(dev);
 145                 device_delete_child(dev, sc->iicbus);
 146         }
 147
 148         return (0);
 149 }
 150
 151 static int
 152 iicbb_print_child(device_t bus, device_t dev)
 153 {
 154         int error;
 155         int retval = 0;
 156         u_char oldaddr;
 157
 158         retval += bus_print_child_header(bus, dev);
 159         /* retrieve the interface I2C address */
 160         error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
 161         if (error == IIC_ENOADDR) {
 162                 retval += kprintf(" on %s master-only\n",
 163                                  device_get_nameunit(bus));
 164         } else {
 165                 /* restore the address */
 166                 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
 167
 168                 retval += kprintf(" on %s addr 0x%x\n",
 169                                  device_get_nameunit(bus), oldaddr & 0xff);
 170         }
 171
 172         return (retval);
 173 }
 174
 175 #define I2C_SET(dev,ctrl,data) \
 176         IICBB_SETLINES(device_get_parent(dev), ctrl, data)
 177
 178 #define I2C_GET(dev) (IICBB_GETDATALINE(device_get_parent(dev)))
 179
 180 static int i2c_debug = 0;
 181 #define I2C_DEBUG(x) if (i2c_debug) (x)
 182
 183 static void
 184 iicbb_one(device_t dev)
 185 {
 186         I2C_SET(dev,0,1);
 187         I2C_SET(dev,1,1);
 188         I2C_SET(dev,0,1);
 189         return;
 190 }
 191
 192 static void
 193 iicbb_zero(device_t dev)
 194 {
 195         I2C_SET(dev,0,0);
 196         I2C_SET(dev,1,0);
 197         I2C_SET(dev,0,0);
 198         return;
 199 }
 200
 201 /*
 202  * Waiting for ACKNOWLEDGE.
 203  *
 204  * When a chip is being addressed or has received data it will issue an
 205  * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
 206  * (set it to high level) and then release the CLOCK line.
 207  * Now it must wait for the SLAVE to pull the DATA line low.
 208  * Actually on the bus this looks like a START condition so nothing happens
 209  * because of the fact that the IC's that have not been addressed are doing
 210  * nothing.
 211  *
 212  * When the SLAVE has pulled this line low the MASTER will take the CLOCK
 213  * line low and then the SLAVE will release the SDA (data) line.
 214  */
 215 static int
 216 iicbb_ack(device_t dev, int timeout)
 217 {
 218         int noack;
 219         int k = timeout/10;
 220
 221         I2C_SET(dev,0,1);
 222         I2C_SET(dev,1,1);
 223
 224         do {
 225                 noack = I2C_GET(dev);
 226                 if (!noack)
 227                         break;
 228                 DELAY(10);              /* XXX wait 10us */
 229         } while (k--);
 230
 231         I2C_SET(dev,0,1);
 232         I2C_DEBUG(kprintf("%c ",noack?'-':'+'));
 233
 234         return (noack);
 235 }
 236
 237 static void
 238 iicbb_sendbyte(device_t dev, u_char data)
 239 {
 240         int i;
 241
 242         I2C_SET(dev,0,0);
 243         for (i=7; i>=0; i--)
 244                 (data&(1<<i)) ? iicbb_one(dev) : iicbb_zero(dev);
 245         I2C_DEBUG(kprintf("w%02x",(int)data));
 246         return;
 247 }
 248
 249 static u_char
 250 iicbb_readbyte(device_t dev, int last)
 251 {
 252         int i;
 253         unsigned char data=0;
 254
 255         I2C_SET(dev,0,1);
 256         for (i=7; i>=0; i--)
 257         {
 258                 I2C_SET(dev,1,1);
 259                 if (I2C_GET(dev))
 260                         data |= (1<<i);
 261                 I2C_SET(dev,0,1);
 262         }
 263         last ? iicbb_one(dev) : iicbb_zero(dev);
 264         I2C_DEBUG(kprintf("r%02x%c ",(int)data,last?'-':'+'));
 265         return data;
 266 }
 267
 268 static int
 269 iicbb_callback(device_t dev, int index, caddr_t data)
 270 {
 271         return (IICBB_CALLBACK(device_get_parent(dev), index, data));
 272 }
 273
 274 static int
 275 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
 276 {
 277         return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
 278 }
 279
 280 static int
 281 iicbb_start(device_t dev, u_char slave, int timeout)
 282 {
 283         int error;
 284
 285         I2C_DEBUG(kprintf("<"));
 286
 287         I2C_SET(dev,0,1);
 288         I2C_SET(dev,1,1);
 289         I2C_SET(dev,1,0);
 290         I2C_SET(dev,0,0);
 291
 292         /* send address */
 293         iicbb_sendbyte(dev, slave);
 294
 295         /* check for ack */
 296         if (iicbb_ack(dev, timeout)) {
 297                 error = IIC_ENOACK;
 298                 goto error;
 299         }
 300
 301         return(0);
 302
 303 error:
 304         iicbb_stop(dev);
 305         return (error);
 306 }
 307
 308 static int
 309 iicbb_stop(device_t dev)
 310 {
 311         I2C_SET(dev,0,0);
 312         I2C_SET(dev,1,0);
 313         I2C_SET(dev,1,1);
 314         I2C_DEBUG(kprintf(">"));
 315         return (0);
 316 }
 317
 318 static int
 319 iicbb_write(device_t dev, char * buf, int len, int *sent, int timeout)
 320 {
 321         int bytes, error = 0;
 322
 323         bytes = 0;
 324         while (len) {
 325                 /* send byte */
 326                 iicbb_sendbyte(dev,(u_char)*buf++);
 327
 328                 /* check for ack */
 329                 if (iicbb_ack(dev, timeout)) {
 330                         error = IIC_ENOACK;
 331                         goto error;
 332                 }
 333                 bytes ++;
 334                 len --;
 335         }
 336
 337 error:
 338         *sent = bytes;
 339         return (error);
 340 }
 341
 342 static int
 343 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
 344 {
 345         int bytes;
 346
 347         bytes = 0;
 348         while (len) {
 349                 /* XXX should insert delay here */
 350                 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0);
 351
 352                 bytes ++;
 353                 len --;
 354         }
 355
 356         *read = bytes;
 357         return (0);
 358 }
 359
 360 DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0);
 361 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
 362 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0);