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 int udelay; /* signal toggle delay in usec */ 65 }; 66 67 static int iicbb_attach(device_t); 68 static void iicbb_child_detached(device_t, device_t); 69 static int iicbb_detach(device_t); 70 static int iicbb_print_child(device_t, device_t); 71 static int iicbb_probe(device_t); 72 73 static int iicbb_callback(device_t, int, caddr_t); 74 static int iicbb_start(device_t, u_char, int); 75 static int iicbb_stop(device_t); 76 static int iicbb_write(device_t, const char *, int, int *, int); 77 static int iicbb_read(device_t, char *, int, int *, int, int); 78 static int iicbb_reset(device_t, u_char, u_char, u_char *); 79 static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs); 80 81 static device_method_t iicbb_methods[] = { 82 /* device interface */ 83 DEVMETHOD(device_probe, iicbb_probe), 84 DEVMETHOD(device_attach, iicbb_attach), 85 DEVMETHOD(device_detach, iicbb_detach), 86 87 /* bus interface */ 88 DEVMETHOD(bus_child_detached, iicbb_child_detached), 89 DEVMETHOD(bus_print_child, iicbb_print_child), 90 91 /* iicbus interface */ 92 DEVMETHOD(iicbus_callback, iicbb_callback), 93 DEVMETHOD(iicbus_start, iicbb_start), 94 DEVMETHOD(iicbus_repeated_start, iicbb_start), 95 DEVMETHOD(iicbus_stop, iicbb_stop), 96 DEVMETHOD(iicbus_write, iicbb_write), 97 DEVMETHOD(iicbus_read, iicbb_read), 98 DEVMETHOD(iicbus_reset, iicbb_reset), 99 DEVMETHOD(iicbus_transfer, iicbb_transfer), 100 101 { 0, 0 } 102 }; 103 104 driver_t iicbb_driver = { 105 "iicbb", 106 iicbb_methods, 107 sizeof(struct iicbb_softc), 108 }; 109 110 devclass_t iicbb_devclass; 111 112 static int 113 iicbb_probe(device_t dev) 114 { 115 device_set_desc(dev, "I2C bit-banging driver"); 116 117 return (0); 118 } 119 120 static int 121 iicbb_attach(device_t dev) 122 { 123 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 124 125 sc->iicbus = device_add_child(dev, "iicbus", -1); 126 if (!sc->iicbus) 127 return (ENXIO); 128 sc->udelay = 10; /* 10 uS default */ 129 bus_generic_attach(dev); 130 131 return (0); 132 } 133 134 static int 135 iicbb_detach(device_t dev) 136 { 137 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 138 device_t child; 139 140 /* 141 * We need to save child because the detach indirectly causes 142 * sc->iicbus to be zeroed. Since we added the device 143 * unconditionally in iicbb_attach, we need to make sure we 144 * delete it here. See iicbb_child_detached. We need that 145 * callback in case newbus detached our children w/o detaching 146 * us (say iicbus is a module and unloaded w/o iicbb being 147 * unloaded). 148 */ 149 child = sc->iicbus; 150 bus_generic_detach(dev); 151 if (child) 152 device_delete_child(dev, child); 153 154 return (0); 155 } 156 157 static void 158 iicbb_child_detached( device_t dev, device_t child ) 159 { 160 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 161 162 if (child == sc->iicbus) 163 sc->iicbus = NULL; 164 } 165 166 static int 167 iicbb_print_child(device_t bus, device_t dev) 168 { 169 int error; 170 int retval = 0; 171 u_char oldaddr; 172 173 retval += bus_print_child_header(bus, dev); 174 /* retrieve the interface I2C address */ 175 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr); 176 if (error == IIC_ENOADDR) { 177 retval += printf(" on %s master-only\n", 178 device_get_nameunit(bus)); 179 } else { 180 /* restore the address */ 181 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL); 182 183 retval += printf(" on %s addr 0x%x\n", 184 device_get_nameunit(bus), oldaddr & 0xff); 185 } 186 187 return (retval); 188 } 189 190 #define I2C_SETSDA(sc,dev,val) do { \ 191 IICBB_SETSDA(device_get_parent(dev), val); \ 192 DELAY(sc->udelay); \ 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(sc,dev,ctrl,data) do { \ 200 I2C_SETSCL(dev, ctrl); \ 201 I2C_SETSDA(sc, 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 struct iicbb_softc *sc = device_get_softc(dev); 221 int k = 0; 222 223 IICBB_SETSCL(device_get_parent(dev), val); 224 DELAY(sc->udelay); 225 226 while (val && !I2C_GETSCL(dev) && k++ < timeout) { 227 IICBB_SETSCL(device_get_parent(dev), val); 228 DELAY(sc->udelay); 229 } 230 231 return; 232 } 233 234 static void 235 iicbb_one(device_t dev, int timeout) 236 { 237 struct iicbb_softc *sc = device_get_softc(dev); 238 239 I2C_SET(sc,dev,0,1); 240 I2C_SET(sc,dev,1,1); 241 I2C_SET(sc,dev,0,1); 242 return; 243 } 244 245 static void 246 iicbb_zero(device_t dev, int timeout) 247 { 248 struct iicbb_softc *sc = device_get_softc(dev); 249 250 I2C_SET(sc,dev,0,0); 251 I2C_SET(sc,dev,1,0); 252 I2C_SET(sc,dev,0,0); 253 return; 254 } 255 256 /* 257 * Waiting for ACKNOWLEDGE. 258 * 259 * When a chip is being addressed or has received data it will issue an 260 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line 261 * (set it to high level) and then release the CLOCK line. 262 * Now it must wait for the SLAVE to pull the DATA line low. 263 * Actually on the bus this looks like a START condition so nothing happens 264 * because of the fact that the IC's that have not been addressed are doing 265 * nothing. 266 * 267 * When the SLAVE has pulled this line low the MASTER will take the CLOCK 268 * line low and then the SLAVE will release the SDA (data) line. 269 */ 270 static int 271 iicbb_ack(device_t dev, int timeout) 272 { 273 struct iicbb_softc *sc = device_get_softc(dev); 274 int noack; 275 int k = 0; 276 277 I2C_SET(sc,dev,0,1); 278 I2C_SET(sc,dev,1,1); 279 do { 280 noack = I2C_GETSDA(dev); 281 if (!noack) 282 break; 283 DELAY(1); 284 k++; 285 } while (k < timeout); 286 287 I2C_SET(sc,dev,0,1); 288 I2C_DEBUG(printf("%c ",noack?'-':'+')); 289 290 return (noack); 291 } 292 293 static void 294 iicbb_sendbyte(device_t dev, u_char data, int timeout) 295 { 296 int i; 297 298 for (i=7; i>=0; i--) { 299 if (data&(1<<i)) { 300 iicbb_one(dev, timeout); 301 } else { 302 iicbb_zero(dev, timeout); 303 } 304 } 305 I2C_DEBUG(printf("w%02x",(int)data)); 306 return; 307 } 308 309 static u_char 310 iicbb_readbyte(device_t dev, int last, int timeout) 311 { 312 struct iicbb_softc *sc = device_get_softc(dev); 313 int i; 314 unsigned char data=0; 315 316 I2C_SET(sc,dev,0,1); 317 for (i=7; i>=0; i--) 318 { 319 I2C_SET(sc,dev,1,1); 320 if (I2C_GETSDA(dev)) 321 data |= (1<<i); 322 I2C_SET(sc,dev,0,1); 323 } 324 if (last) { 325 iicbb_one(dev, timeout); 326 } else { 327 iicbb_zero(dev, timeout); 328 } 329 I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+')); 330 return data; 331 } 332 333 static int 334 iicbb_callback(device_t dev, int index, caddr_t data) 335 { 336 return (IICBB_CALLBACK(device_get_parent(dev), index, data)); 337 } 338 339 static int 340 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr) 341 { 342 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr)); 343 } 344 345 static int 346 iicbb_start(device_t dev, u_char slave, int timeout) 347 { 348 struct iicbb_softc *sc = device_get_softc(dev); 349 int error; 350 351 I2C_DEBUG(printf("<")); 352 353 I2C_SET(sc,dev,1,1); 354 I2C_SET(sc,dev,1,0); 355 I2C_SET(sc,dev,0,0); 356 357 /* send address */ 358 iicbb_sendbyte(dev, slave, timeout); 359 360 /* check for ack */ 361 if (iicbb_ack(dev, timeout)) { 362 error = IIC_ENOACK; 363 goto error; 364 } 365 366 return(0); 367 368 error: 369 iicbb_stop(dev); 370 return (error); 371 } 372 373 static int 374 iicbb_stop(device_t dev) 375 { 376 struct iicbb_softc *sc = device_get_softc(dev); 377 378 I2C_SET(sc,dev,0,0); 379 I2C_SET(sc,dev,1,0); 380 I2C_SET(sc,dev,1,1); 381 I2C_DEBUG(printf(">")); 382 I2C_DEBUG(printf("\n")); 383 return (0); 384 } 385 386 static int 387 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout) 388 { 389 int bytes, error = 0; 390 391 bytes = 0; 392 while (len) { 393 /* send byte */ 394 iicbb_sendbyte(dev,(u_char)*buf++, timeout); 395 396 /* check for ack */ 397 if (iicbb_ack(dev, timeout)) { 398 error = IIC_ENOACK; 399 goto error; 400 } 401 bytes ++; 402 len --; 403 } 404 405 error: 406 *sent = bytes; 407 return (error); 408 } 409 410 static int 411 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay) 412 { 413 int bytes; 414 415 bytes = 0; 416 while (len) { 417 /* XXX should insert delay here */ 418 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay); 419 420 bytes ++; 421 len --; 422 } 423 424 *read = bytes; 425 return (0); 426 } 427 428 static int 429 iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs) 430 { 431 int error; 432 433 error = IICBB_PRE_XFER(device_get_parent(dev)); 434 if (error) 435 return (error); 436 437 error = iicbus_transfer_gen(dev, msgs, nmsgs); 438 439 IICBB_POST_XFER(device_get_parent(dev)); 440 return (error); 441 } 442 443 DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0); 444 445 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER); 446 MODULE_VERSION(iicbb, IICBB_MODVER); 447