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 { 152 153 bus_generic_detach(dev); 154 device_delete_children(dev); 155 156 return (0); 157 } 158 159 #ifdef FDT 160 static phandle_t 161 iicbb_get_node(device_t bus, device_t dev) 162 { 163 164 /* We only have one child, the I2C bus, which needs our own node. */ 165 return (ofw_bus_get_node(bus)); 166 } 167 #endif 168 169 static void 170 iicbb_child_detached( device_t dev, device_t child ) 171 { 172 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 173 174 if (child == sc->iicbus) 175 sc->iicbus = NULL; 176 } 177 178 static int 179 iicbb_print_child(device_t bus, device_t dev) 180 { 181 int error; 182 int retval = 0; 183 u_char oldaddr; 184 185 retval += bus_print_child_header(bus, dev); 186 /* retrieve the interface I2C address */ 187 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr); 188 if (error == IIC_ENOADDR) { 189 retval += printf(" on %s master-only\n", 190 device_get_nameunit(bus)); 191 } else { 192 /* restore the address */ 193 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL); 194 195 retval += printf(" on %s addr 0x%x\n", 196 device_get_nameunit(bus), oldaddr & 0xff); 197 } 198 199 return (retval); 200 } 201 202 #define I2C_SETSDA(sc,dev,val) do { \ 203 IICBB_SETSDA(device_get_parent(dev), val); \ 204 DELAY(sc->udelay); \ 205 } while (0) 206 207 #define I2C_SETSCL(dev,val) do { \ 208 iicbb_setscl(dev, val, 100); \ 209 } while (0) 210 211 #define I2C_SET(sc,dev,ctrl,data) do { \ 212 I2C_SETSCL(dev, ctrl); \ 213 I2C_SETSDA(sc, dev, data); \ 214 } while (0) 215 216 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev))) 217 218 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev))) 219 220 static int i2c_debug = 0; 221 #define I2C_DEBUG(x) do { \ 222 if (i2c_debug) (x); \ 223 } while (0) 224 225 #define I2C_LOG(format,args...) do { \ 226 printf(format, args); \ 227 } while (0) 228 229 static void 230 iicbb_setscl(device_t dev, int val, int timeout) 231 { 232 struct iicbb_softc *sc = device_get_softc(dev); 233 int k = 0; 234 235 IICBB_SETSCL(device_get_parent(dev), val); 236 DELAY(sc->udelay); 237 238 while (val && !I2C_GETSCL(dev) && k++ < timeout) { 239 IICBB_SETSCL(device_get_parent(dev), val); 240 DELAY(sc->udelay); 241 } 242 243 return; 244 } 245 246 static void 247 iicbb_one(device_t dev, int timeout) 248 { 249 struct iicbb_softc *sc = device_get_softc(dev); 250 251 I2C_SET(sc,dev,0,1); 252 I2C_SET(sc,dev,1,1); 253 I2C_SET(sc,dev,0,1); 254 return; 255 } 256 257 static void 258 iicbb_zero(device_t dev, int timeout) 259 { 260 struct iicbb_softc *sc = device_get_softc(dev); 261 262 I2C_SET(sc,dev,0,0); 263 I2C_SET(sc,dev,1,0); 264 I2C_SET(sc,dev,0,0); 265 return; 266 } 267 268 /* 269 * Waiting for ACKNOWLEDGE. 270 * 271 * When a chip is being addressed or has received data it will issue an 272 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line 273 * (set it to high level) and then release the CLOCK line. 274 * Now it must wait for the SLAVE to pull the DATA line low. 275 * Actually on the bus this looks like a START condition so nothing happens 276 * because of the fact that the IC's that have not been addressed are doing 277 * nothing. 278 * 279 * When the SLAVE has pulled this line low the MASTER will take the CLOCK 280 * line low and then the SLAVE will release the SDA (data) line. 281 */ 282 static int 283 iicbb_ack(device_t dev, int timeout) 284 { 285 struct iicbb_softc *sc = device_get_softc(dev); 286 int noack; 287 int k = 0; 288 289 I2C_SET(sc,dev,0,1); 290 I2C_SET(sc,dev,1,1); 291 do { 292 noack = I2C_GETSDA(dev); 293 if (!noack) 294 break; 295 DELAY(1); 296 k++; 297 } while (k < timeout); 298 299 I2C_SET(sc,dev,0,1); 300 I2C_DEBUG(printf("%c ",noack?'-':'+')); 301 302 return (noack); 303 } 304 305 static void 306 iicbb_sendbyte(device_t dev, u_char data, int timeout) 307 { 308 int i; 309 310 for (i=7; i>=0; i--) { 311 if (data&(1<<i)) { 312 iicbb_one(dev, timeout); 313 } else { 314 iicbb_zero(dev, timeout); 315 } 316 } 317 I2C_DEBUG(printf("w%02x",(int)data)); 318 return; 319 } 320 321 static u_char 322 iicbb_readbyte(device_t dev, int last, int timeout) 323 { 324 struct iicbb_softc *sc = device_get_softc(dev); 325 int i; 326 unsigned char data=0; 327 328 I2C_SET(sc,dev,0,1); 329 for (i=7; i>=0; i--) 330 { 331 I2C_SET(sc,dev,1,1); 332 if (I2C_GETSDA(dev)) 333 data |= (1<<i); 334 I2C_SET(sc,dev,0,1); 335 } 336 if (last) { 337 iicbb_one(dev, timeout); 338 } else { 339 iicbb_zero(dev, timeout); 340 } 341 I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+')); 342 return data; 343 } 344 345 static int 346 iicbb_callback(device_t dev, int index, caddr_t data) 347 { 348 return (IICBB_CALLBACK(device_get_parent(dev), index, data)); 349 } 350 351 static int 352 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr) 353 { 354 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr)); 355 } 356 357 static int 358 iicbb_start(device_t dev, u_char slave, int timeout) 359 { 360 struct iicbb_softc *sc = device_get_softc(dev); 361 int error; 362 363 I2C_DEBUG(printf("<")); 364 365 I2C_SET(sc,dev,1,1); 366 I2C_SET(sc,dev,1,0); 367 I2C_SET(sc,dev,0,0); 368 369 /* send address */ 370 iicbb_sendbyte(dev, slave, timeout); 371 372 /* check for ack */ 373 if (iicbb_ack(dev, timeout)) { 374 error = IIC_ENOACK; 375 goto error; 376 } 377 378 return(0); 379 380 error: 381 iicbb_stop(dev); 382 return (error); 383 } 384 385 static int 386 iicbb_stop(device_t dev) 387 { 388 struct iicbb_softc *sc = device_get_softc(dev); 389 390 I2C_SET(sc,dev,0,0); 391 I2C_SET(sc,dev,1,0); 392 I2C_SET(sc,dev,1,1); 393 I2C_DEBUG(printf(">")); 394 I2C_DEBUG(printf("\n")); 395 return (0); 396 } 397 398 static int 399 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout) 400 { 401 int bytes, error = 0; 402 403 bytes = 0; 404 while (len) { 405 /* send byte */ 406 iicbb_sendbyte(dev,(u_char)*buf++, timeout); 407 408 /* check for ack */ 409 if (iicbb_ack(dev, timeout)) { 410 error = IIC_ENOACK; 411 goto error; 412 } 413 bytes ++; 414 len --; 415 } 416 417 error: 418 *sent = bytes; 419 return (error); 420 } 421 422 static int 423 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay) 424 { 425 int bytes; 426 427 bytes = 0; 428 while (len) { 429 /* XXX should insert delay here */ 430 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay); 431 432 bytes ++; 433 len --; 434 } 435 436 *read = bytes; 437 return (0); 438 } 439 440 static int 441 iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs) 442 { 443 int error; 444 445 error = IICBB_PRE_XFER(device_get_parent(dev)); 446 if (error) 447 return (error); 448 449 error = iicbus_transfer_gen(dev, msgs, nmsgs); 450 451 IICBB_POST_XFER(device_get_parent(dev)); 452 return (error); 453 } 454 455 DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0); 456 457 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER); 458 MODULE_VERSION(iicbb, IICBB_MODVER); 459