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 "opt_platform.h" 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/uio.h> 54 55 #ifdef FDT 56 #include <dev/ofw/ofw_bus.h> 57 #include <dev/ofw/ofw_bus_subr.h> 58 #include <dev/fdt/fdt_common.h> 59 #endif 60 61 #include <dev/iicbus/iiconf.h> 62 #include <dev/iicbus/iicbus.h> 63 64 #include <dev/smbus/smbconf.h> 65 66 #include "iicbus_if.h" 67 #include "iicbb_if.h" 68 69 struct iicbb_softc { 70 device_t iicbus; 71 int udelay; /* signal toggle delay in usec */ 72 }; 73 74 static int iicbb_attach(device_t); 75 static void iicbb_child_detached(device_t, device_t); 76 static int iicbb_detach(device_t); 77 static int iicbb_print_child(device_t, device_t); 78 static int iicbb_probe(device_t); 79 80 static int iicbb_callback(device_t, int, caddr_t); 81 static int iicbb_start(device_t, u_char, int); 82 static int iicbb_stop(device_t); 83 static int iicbb_write(device_t, const char *, int, int *, int); 84 static int iicbb_read(device_t, char *, int, int *, int, int); 85 static int iicbb_reset(device_t, u_char, u_char, u_char *); 86 static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs); 87 #ifdef FDT 88 static phandle_t iicbb_get_node(device_t, device_t); 89 #endif 90 91 static device_method_t iicbb_methods[] = { 92 /* device interface */ 93 DEVMETHOD(device_probe, iicbb_probe), 94 DEVMETHOD(device_attach, iicbb_attach), 95 DEVMETHOD(device_detach, iicbb_detach), 96 97 /* bus interface */ 98 DEVMETHOD(bus_child_detached, iicbb_child_detached), 99 DEVMETHOD(bus_print_child, iicbb_print_child), 100 101 /* iicbus interface */ 102 DEVMETHOD(iicbus_callback, iicbb_callback), 103 DEVMETHOD(iicbus_start, iicbb_start), 104 DEVMETHOD(iicbus_repeated_start, iicbb_start), 105 DEVMETHOD(iicbus_stop, iicbb_stop), 106 DEVMETHOD(iicbus_write, iicbb_write), 107 DEVMETHOD(iicbus_read, iicbb_read), 108 DEVMETHOD(iicbus_reset, iicbb_reset), 109 DEVMETHOD(iicbus_transfer, iicbb_transfer), 110 111 #ifdef FDT 112 /* ofw_bus interface */ 113 DEVMETHOD(ofw_bus_get_node, iicbb_get_node), 114 #endif 115 116 { 0, 0 } 117 }; 118 119 driver_t iicbb_driver = { 120 "iicbb", 121 iicbb_methods, 122 sizeof(struct iicbb_softc), 123 }; 124 125 devclass_t iicbb_devclass; 126 127 static int 128 iicbb_probe(device_t dev) 129 { 130 device_set_desc(dev, "I2C bit-banging driver"); 131 132 return (0); 133 } 134 135 static int 136 iicbb_attach(device_t dev) 137 { 138 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 139 140 sc->iicbus = device_add_child(dev, "iicbus", -1); 141 if (!sc->iicbus) 142 return (ENXIO); 143 sc->udelay = 10; /* 10 uS default */ 144 bus_generic_attach(dev); 145 146 return (0); 147 } 148 149 static int 150 iicbb_detach(device_t dev) 151 { 152 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 153 device_t child; 154 155 /* 156 * We need to save child because the detach indirectly causes 157 * sc->iicbus to be zeroed. Since we added the device 158 * unconditionally in iicbb_attach, we need to make sure we 159 * delete it here. See iicbb_child_detached. We need that 160 * callback in case newbus detached our children w/o detaching 161 * us (say iicbus is a module and unloaded w/o iicbb being 162 * unloaded). 163 */ 164 child = sc->iicbus; 165 bus_generic_detach(dev); 166 if (child) 167 device_delete_child(dev, child); 168 169 return (0); 170 } 171 172 #ifdef FDT 173 static phandle_t 174 iicbb_get_node(device_t bus, device_t dev) 175 { 176 177 /* We only have one child, the I2C bus, which needs our own node. */ 178 return (ofw_bus_get_node(bus)); 179 } 180 #endif 181 182 static void 183 iicbb_child_detached( device_t dev, device_t child ) 184 { 185 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 186 187 if (child == sc->iicbus) 188 sc->iicbus = NULL; 189 } 190 191 static int 192 iicbb_print_child(device_t bus, device_t dev) 193 { 194 int error; 195 int retval = 0; 196 u_char oldaddr; 197 198 retval += bus_print_child_header(bus, dev); 199 /* retrieve the interface I2C address */ 200 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr); 201 if (error == IIC_ENOADDR) { 202 retval += printf(" on %s master-only\n", 203 device_get_nameunit(bus)); 204 } else { 205 /* restore the address */ 206 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL); 207 208 retval += printf(" on %s addr 0x%x\n", 209 device_get_nameunit(bus), oldaddr & 0xff); 210 } 211 212 return (retval); 213 } 214 215 #define I2C_SETSDA(sc,dev,val) do { \ 216 IICBB_SETSDA(device_get_parent(dev), val); \ 217 DELAY(sc->udelay); \ 218 } while (0) 219 220 #define I2C_SETSCL(dev,val) do { \ 221 iicbb_setscl(dev, val, 100); \ 222 } while (0) 223 224 #define I2C_SET(sc,dev,ctrl,data) do { \ 225 I2C_SETSCL(dev, ctrl); \ 226 I2C_SETSDA(sc, dev, data); \ 227 } while (0) 228 229 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev))) 230 231 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev))) 232 233 static int i2c_debug = 0; 234 #define I2C_DEBUG(x) do { \ 235 if (i2c_debug) (x); \ 236 } while (0) 237 238 #define I2C_LOG(format,args...) do { \ 239 printf(format, args); \ 240 } while (0) 241 242 static void 243 iicbb_setscl(device_t dev, int val, int timeout) 244 { 245 struct iicbb_softc *sc = device_get_softc(dev); 246 int k = 0; 247 248 IICBB_SETSCL(device_get_parent(dev), val); 249 DELAY(sc->udelay); 250 251 while (val && !I2C_GETSCL(dev) && k++ < timeout) { 252 IICBB_SETSCL(device_get_parent(dev), val); 253 DELAY(sc->udelay); 254 } 255 256 return; 257 } 258 259 static void 260 iicbb_one(device_t dev, int timeout) 261 { 262 struct iicbb_softc *sc = device_get_softc(dev); 263 264 I2C_SET(sc,dev,0,1); 265 I2C_SET(sc,dev,1,1); 266 I2C_SET(sc,dev,0,1); 267 return; 268 } 269 270 static void 271 iicbb_zero(device_t dev, int timeout) 272 { 273 struct iicbb_softc *sc = device_get_softc(dev); 274 275 I2C_SET(sc,dev,0,0); 276 I2C_SET(sc,dev,1,0); 277 I2C_SET(sc,dev,0,0); 278 return; 279 } 280 281 /* 282 * Waiting for ACKNOWLEDGE. 283 * 284 * When a chip is being addressed or has received data it will issue an 285 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line 286 * (set it to high level) and then release the CLOCK line. 287 * Now it must wait for the SLAVE to pull the DATA line low. 288 * Actually on the bus this looks like a START condition so nothing happens 289 * because of the fact that the IC's that have not been addressed are doing 290 * nothing. 291 * 292 * When the SLAVE has pulled this line low the MASTER will take the CLOCK 293 * line low and then the SLAVE will release the SDA (data) line. 294 */ 295 static int 296 iicbb_ack(device_t dev, int timeout) 297 { 298 struct iicbb_softc *sc = device_get_softc(dev); 299 int noack; 300 int k = 0; 301 302 I2C_SET(sc,dev,0,1); 303 I2C_SET(sc,dev,1,1); 304 do { 305 noack = I2C_GETSDA(dev); 306 if (!noack) 307 break; 308 DELAY(1); 309 k++; 310 } while (k < timeout); 311 312 I2C_SET(sc,dev,0,1); 313 I2C_DEBUG(printf("%c ",noack?'-':'+')); 314 315 return (noack); 316 } 317 318 static void 319 iicbb_sendbyte(device_t dev, u_char data, int timeout) 320 { 321 int i; 322 323 for (i=7; i>=0; i--) { 324 if (data&(1<<i)) { 325 iicbb_one(dev, timeout); 326 } else { 327 iicbb_zero(dev, timeout); 328 } 329 } 330 I2C_DEBUG(printf("w%02x",(int)data)); 331 return; 332 } 333 334 static u_char 335 iicbb_readbyte(device_t dev, int last, int timeout) 336 { 337 struct iicbb_softc *sc = device_get_softc(dev); 338 int i; 339 unsigned char data=0; 340 341 I2C_SET(sc,dev,0,1); 342 for (i=7; i>=0; i--) 343 { 344 I2C_SET(sc,dev,1,1); 345 if (I2C_GETSDA(dev)) 346 data |= (1<<i); 347 I2C_SET(sc,dev,0,1); 348 } 349 if (last) { 350 iicbb_one(dev, timeout); 351 } else { 352 iicbb_zero(dev, timeout); 353 } 354 I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+')); 355 return data; 356 } 357 358 static int 359 iicbb_callback(device_t dev, int index, caddr_t data) 360 { 361 return (IICBB_CALLBACK(device_get_parent(dev), index, data)); 362 } 363 364 static int 365 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr) 366 { 367 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr)); 368 } 369 370 static int 371 iicbb_start(device_t dev, u_char slave, int timeout) 372 { 373 struct iicbb_softc *sc = device_get_softc(dev); 374 int error; 375 376 I2C_DEBUG(printf("<")); 377 378 I2C_SET(sc,dev,1,1); 379 I2C_SET(sc,dev,1,0); 380 I2C_SET(sc,dev,0,0); 381 382 /* send address */ 383 iicbb_sendbyte(dev, slave, timeout); 384 385 /* check for ack */ 386 if (iicbb_ack(dev, timeout)) { 387 error = IIC_ENOACK; 388 goto error; 389 } 390 391 return(0); 392 393 error: 394 iicbb_stop(dev); 395 return (error); 396 } 397 398 static int 399 iicbb_stop(device_t dev) 400 { 401 struct iicbb_softc *sc = device_get_softc(dev); 402 403 I2C_SET(sc,dev,0,0); 404 I2C_SET(sc,dev,1,0); 405 I2C_SET(sc,dev,1,1); 406 I2C_DEBUG(printf(">")); 407 I2C_DEBUG(printf("\n")); 408 return (0); 409 } 410 411 static int 412 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout) 413 { 414 int bytes, error = 0; 415 416 bytes = 0; 417 while (len) { 418 /* send byte */ 419 iicbb_sendbyte(dev,(u_char)*buf++, timeout); 420 421 /* check for ack */ 422 if (iicbb_ack(dev, timeout)) { 423 error = IIC_ENOACK; 424 goto error; 425 } 426 bytes ++; 427 len --; 428 } 429 430 error: 431 *sent = bytes; 432 return (error); 433 } 434 435 static int 436 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay) 437 { 438 int bytes; 439 440 bytes = 0; 441 while (len) { 442 /* XXX should insert delay here */ 443 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay); 444 445 bytes ++; 446 len --; 447 } 448 449 *read = bytes; 450 return (0); 451 } 452 453 static int 454 iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs) 455 { 456 int error; 457 458 error = IICBB_PRE_XFER(device_get_parent(dev)); 459 if (error) 460 return (error); 461 462 error = iicbus_transfer_gen(dev, msgs, nmsgs); 463 464 IICBB_POST_XFER(device_get_parent(dev)); 465 return (error); 466 } 467 468 DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0); 469 470 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER); 471 MODULE_VERSION(iicbb, IICBB_MODVER); 472