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_attach(device_t);
  73 static void iicbb_child_detached(device_t, device_t);
  74 static int iicbb_detach(device_t);
  75 static int iicbb_print_child(device_t, device_t);
  76 static int iicbb_probe(device_t);
  77
  78 static int iicbb_callback(device_t, int, caddr_t);
  79 static int iicbb_start(device_t, u_char, int);
  80 static int iicbb_stop(device_t);
  81 static int iicbb_write(device_t, const char *, int, int *, int);
  82 static int iicbb_read(device_t, char *, int, int *, int, int);
  83 static int iicbb_reset(device_t, u_char, u_char, u_char *);
  84
  85 static device_method_t iicbb_methods[] = {
  86         /* device interface */
  87         DEVMETHOD(device_probe,         iicbb_probe),
  88         DEVMETHOD(device_attach,        iicbb_attach),
  89         DEVMETHOD(device_detach,        iicbb_detach),
  90
  91         /* bus interface */
  92         DEVMETHOD(bus_child_detached,   iicbb_child_detached),
  93         DEVMETHOD(bus_print_child,      iicbb_print_child),
  94
  95         /* iicbus interface */
  96         DEVMETHOD(iicbus_callback,      iicbb_callback),
  97         DEVMETHOD(iicbus_start,         iicbb_start),
  98         DEVMETHOD(iicbus_repeated_start, iicbb_start),
  99         DEVMETHOD(iicbus_stop,          iicbb_stop),
 100         DEVMETHOD(iicbus_write,         iicbb_write),
 101         DEVMETHOD(iicbus_read,          iicbb_read),
 102         DEVMETHOD(iicbus_reset,         iicbb_reset),
 103
 104         { 0, 0 }
 105 };
 106
 107 static driver_t iicbb_driver = {
 108         "iicbb",
 109         iicbb_methods,
 110         sizeof(struct iicbb_softc),
 111 };
 112
 113 static devclass_t iicbb_devclass;
 114
 115 static int
 116 iicbb_probe(device_t dev)
 117 {
 118         device_set_desc(dev, "I2C bit-banging driver");
 119
 120         return (0);
 121 }
 122
 123 static int
 124 iicbb_attach(device_t dev)
 125 {
 126         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 127
 128         sc->iicbus = device_add_child(dev, "iicbus", -1);
 129         if (!sc->iicbus)
 130                 return (ENXIO);
 131         bus_generic_attach(dev);
 132
 133         return (0);
 134 }
 135
 136 static int
 137 iicbb_detach(device_t dev)
 138 {
 139         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 140         device_t child;
 141
 142         /*
 143          * We need to save child because the detach indirectly causes
 144          * sc->iicbus to be zeroed.  Since we added the device
 145          * unconditionally in iicbb_attach, we need to make sure we
 146          * delete it here.  See iicbb_child_detached.  We need that
 147          * callback in case newbus detached our children w/o detaching
 148          * us (say iicbus is a module and unloaded w/o iicbb being
 149          * unloaded).
 150          */
 151         child = sc->iicbus;
 152         bus_generic_detach(dev);
 153         if (child)
 154                 device_delete_child(dev, child);
 155
 156         return (0);
 157 }
 158
 159 static void
 160 iicbb_child_detached(device_t dev, device_t child)
 161 {
 162         struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
 163
 164         if (child == sc->iicbus)
 165                 sc->iicbus = NULL;
 166 }
 167
 168 static int
 169 iicbb_print_child(device_t bus, device_t dev)
 170 {
 171         int error;
 172         int retval = 0;
 173         u_char oldaddr;
 174
 175         retval += bus_print_child_header(bus, dev);
 176         /* retrieve the interface I2C address */
 177         error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
 178         if (error == IIC_ENOADDR) {
 179                 retval += kprintf(" on %s master-only\n",
 180                                  device_get_nameunit(bus));
 181         } else {
 182                 /* restore the address */
 183                 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
 184
 185                 retval += kprintf(" on %s addr 0x%x\n",
 186                                  device_get_nameunit(bus), oldaddr & 0xff);
 187         }
 188
 189         return (retval);
 190 }
 191
 192 #define I2C_SET(dev,ctrl,data) \
 193         IICBB_SETLINES(device_get_parent(dev), ctrl, data)
 194
 195 #define I2C_GET(dev) (IICBB_GETDATALINE(device_get_parent(dev)))
 196
 197 static int i2c_debug = 0;
 198 #define I2C_DEBUG(x) if (i2c_debug) (x)
 199
 200 static void
 201 iicbb_one(device_t dev)
 202 {
 203         I2C_SET(dev,0,1);
 204         I2C_SET(dev,1,1);
 205         I2C_SET(dev,0,1);
 206         return;
 207 }
 208
 209 static void
 210 iicbb_zero(device_t dev)
 211 {
 212         I2C_SET(dev,0,0);
 213         I2C_SET(dev,1,0);
 214         I2C_SET(dev,0,0);
 215         return;
 216 }
 217
 218 /*
 219  * Waiting for ACKNOWLEDGE.
 220  *
 221  * When a chip is being addressed or has received data it will issue an
 222  * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
 223  * (set it to high level) and then release the CLOCK line.
 224  * Now it must wait for the SLAVE to pull the DATA line low.
 225  * Actually on the bus this looks like a START condition so nothing happens
 226  * because of the fact that the IC's that have not been addressed are doing
 227  * nothing.
 228  *
 229  * When the SLAVE has pulled this line low the MASTER will take the CLOCK
 230  * line low and then the SLAVE will release the SDA (data) line.
 231  */
 232 static int
 233 iicbb_ack(device_t dev, int timeout)
 234 {
 235         int noack;
 236         int k = timeout/10;
 237
 238         I2C_SET(dev,0,1);
 239         I2C_SET(dev,1,1);
 240
 241         do {
 242                 noack = I2C_GET(dev);
 243                 if (!noack)
 244                         break;
 245                 DELAY(10);              /* XXX wait 10us */
 246         } while (k--);
 247
 248         I2C_SET(dev,0,1);
 249         I2C_DEBUG(kprintf("%c ",noack?'-':'+'));
 250
 251         return (noack);
 252 }
 253
 254 static void
 255 iicbb_sendbyte(device_t dev, u_char data)
 256 {
 257         int i;
 258
 259         I2C_SET(dev,0,0);
 260         for (i=7; i>=0; i--)
 261                 (data&(1<<i)) ? iicbb_one(dev) : iicbb_zero(dev);
 262         I2C_DEBUG(kprintf("w%02x",(int)data));
 263         return;
 264 }
 265
 266 static u_char
 267 iicbb_readbyte(device_t dev, int last)
 268 {
 269         int i;
 270         unsigned char data=0;
 271
 272         I2C_SET(dev,0,1);
 273         for (i=7; i>=0; i--)
 274         {
 275                 I2C_SET(dev,1,1);
 276                 if (I2C_GET(dev))
 277                         data |= (1<<i);
 278                 I2C_SET(dev,0,1);
 279         }
 280         last ? iicbb_one(dev) : iicbb_zero(dev);
 281         I2C_DEBUG(kprintf("r%02x%c ",(int)data,last?'-':'+'));
 282         return data;
 283 }
 284
 285 static int
 286 iicbb_callback(device_t dev, int index, caddr_t data)
 287 {
 288         return (IICBB_CALLBACK(device_get_parent(dev), index, data));
 289 }
 290
 291 static int
 292 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
 293 {
 294         return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
 295 }
 296
 297 static int
 298 iicbb_start(device_t dev, u_char slave, int timeout)
 299 {
 300         int error;
 301
 302         I2C_DEBUG(kprintf("<"));
 303
 304         I2C_SET(dev,0,1);
 305         I2C_SET(dev,1,1);
 306         I2C_SET(dev,1,0);
 307         I2C_SET(dev,0,0);
 308
 309         /* send address */
 310         iicbb_sendbyte(dev, slave);
 311
 312         /* check for ack */
 313         if (iicbb_ack(dev, timeout)) {
 314                 error = IIC_ENOACK;
 315                 goto error;
 316         }
 317
 318         return(0);
 319
 320 error:
 321         iicbb_stop(dev);
 322         return (error);
 323 }
 324
 325 static int
 326 iicbb_stop(device_t dev)
 327 {
 328         I2C_SET(dev,0,0);
 329         I2C_SET(dev,1,0);
 330         I2C_SET(dev,1,1);
 331         I2C_DEBUG(kprintf(">"));
 332         return (0);
 333 }
 334
 335 static int
 336 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
 337 {
 338         int bytes, error = 0;
 339
 340         bytes = 0;
 341         while (len) {
 342                 /* send byte */
 343                 iicbb_sendbyte(dev,(u_char)*buf++);
 344
 345                 /* check for ack */
 346                 if (iicbb_ack(dev, timeout)) {
 347                         error = IIC_ENOACK;
 348                         goto error;
 349                 }
 350                 bytes ++;
 351                 len --;
 352         }
 353
 354 error:
 355         *sent = bytes;
 356         return (error);
 357 }
 358
 359 static int
 360 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
 361 {
 362         int bytes;
 363
 364         bytes = 0;
 365         while (len) {
 366                 /* XXX should insert delay here */
 367                 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0);
 368
 369                 bytes ++;
 370                 len --;
 371         }
 372
 373         *read = bytes;
 374         return (0);
 375 }
 376
 377 DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0);
 378 DRIVER_MODULE(iicbb, cxm_iic, iicbb_driver, iicbb_devclass, 0, 0);
 379 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
 380 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0);