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 * $FreeBSD: head/sys/dev/iicbus/iicbb.c 232365 2012-03-01 20:58:20Z kan $ 27 */ 28 29 /* 30 * Generic I2C bit-banging code 31 * 32 * Example: 33 * 34 * iicbus 35 * / \ 36 * iicbb pcf 37 * | \ 38 * bti2c lpbb 39 * 40 * From Linux I2C generic interface 41 * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de> 42 * 43 */ 44 45 #include <sys/param.h> 46 #include <sys/kernel.h> 47 #include <sys/systm.h> 48 #include <sys/module.h> 49 #include <sys/bus.h> 50 #include <sys/uio.h> 51 52 #include <bus/iicbus/iiconf.h> 53 #include <bus/iicbus/iicbus.h> 54 55 #include <bus/smbus/smbconf.h> 56 57 #include "iicbus_if.h" 58 #include "iicbb_if.h" 59 60 struct iicbb_softc { 61 device_t iicbus; 62 int udelay; /* signal toggle delay in usec */ 63 }; 64 65 static int iicbb_attach(device_t); 66 static void iicbb_child_detached(device_t, device_t); 67 static int iicbb_detach(device_t); 68 static int iicbb_print_child(device_t, device_t); 69 static int iicbb_probe(device_t); 70 71 static int iicbb_callback(device_t, int, caddr_t); 72 static int iicbb_start(device_t, u_char, int); 73 static int iicbb_stop(device_t); 74 static int iicbb_write(device_t, const char *, int, int *, int); 75 static int iicbb_read(device_t, char *, int, int *, int, int); 76 static int iicbb_reset(device_t, u_char, u_char, u_char *); 77 static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs); 78 79 static device_method_t iicbb_methods[] = { 80 /* device interface */ 81 DEVMETHOD(device_probe, iicbb_probe), 82 DEVMETHOD(device_attach, iicbb_attach), 83 DEVMETHOD(device_detach, iicbb_detach), 84 85 /* bus interface */ 86 DEVMETHOD(bus_child_detached, iicbb_child_detached), 87 DEVMETHOD(bus_print_child, iicbb_print_child), 88 89 /* iicbus interface */ 90 DEVMETHOD(iicbus_callback, iicbb_callback), 91 DEVMETHOD(iicbus_start, iicbb_start), 92 DEVMETHOD(iicbus_repeated_start, iicbb_start), 93 DEVMETHOD(iicbus_stop, iicbb_stop), 94 DEVMETHOD(iicbus_write, iicbb_write), 95 DEVMETHOD(iicbus_read, iicbb_read), 96 DEVMETHOD(iicbus_reset, iicbb_reset), 97 DEVMETHOD(iicbus_transfer, iicbb_transfer), 98 99 DEVMETHOD_END 100 }; 101 102 driver_t iicbb_driver = { 103 "iicbb", 104 iicbb_methods, 105 sizeof(struct iicbb_softc), 106 }; 107 108 devclass_t iicbb_devclass; 109 110 static int 111 iicbb_probe(device_t dev) 112 { 113 device_set_desc(dev, "I2C bit-banging driver"); 114 115 return (0); 116 } 117 118 static int 119 iicbb_attach(device_t dev) 120 { 121 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 122 123 sc->iicbus = device_add_child(dev, "iicbus", -1); 124 if (!sc->iicbus) 125 return (ENXIO); 126 sc->udelay = 10; /* 10 uS default */ 127 bus_generic_attach(dev); 128 129 return (0); 130 } 131 132 static int 133 iicbb_detach(device_t dev) 134 { 135 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 136 device_t child; 137 138 /* 139 * We need to save child because the detach indirectly causes 140 * sc->iicbus to be zeroed. Since we added the device 141 * unconditionally in iicbb_attach, we need to make sure we 142 * delete it here. See iicbb_child_detached. We need that 143 * callback in case newbus detached our children w/o detaching 144 * us (say iicbus is a module and unloaded w/o iicbb being 145 * unloaded). 146 */ 147 child = sc->iicbus; 148 bus_generic_detach(dev); 149 if (child) 150 device_delete_child(dev, child); 151 152 return (0); 153 } 154 155 static void 156 iicbb_child_detached( device_t dev, device_t child ) 157 { 158 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 159 160 if (child == sc->iicbus) 161 sc->iicbus = NULL; 162 } 163 164 static int 165 iicbb_print_child(device_t bus, device_t dev) 166 { 167 int error; 168 int retval = 0; 169 u_char oldaddr; 170 171 retval += bus_print_child_header(bus, dev); 172 /* retrieve the interface I2C address */ 173 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr); 174 if (error == IIC_ENOADDR) { 175 retval += kprintf(" on %s master-only\n", 176 device_get_nameunit(bus)); 177 } else { 178 /* restore the address */ 179 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL); 180 181 retval += kprintf(" on %s addr 0x%x\n", 182 device_get_nameunit(bus), oldaddr & 0xff); 183 } 184 185 return (retval); 186 } 187 188 #define I2C_SETSDA(sc,dev,val) do { \ 189 IICBB_SETSDA(device_get_parent(dev), val); \ 190 DELAY(sc->udelay); \ 191 } while (0) 192 193 #define I2C_SETSCL(dev,val) do { \ 194 iicbb_setscl(dev, val, 100); \ 195 } while (0) 196 197 #define I2C_SET(sc,dev,ctrl,data) do { \ 198 I2C_SETSCL(dev, ctrl); \ 199 I2C_SETSDA(sc, dev, data); \ 200 } while (0) 201 202 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev))) 203 204 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev))) 205 206 static int i2c_debug = 0; 207 #define I2C_DEBUG(x) do { \ 208 if (i2c_debug) (x); \ 209 } while (0) 210 211 #define I2C_LOG(format,args...) do { \ 212 kprintf(format, args); \ 213 } while (0) 214 215 static void 216 iicbb_setscl(device_t dev, int val, int timeout) 217 { 218 struct iicbb_softc *sc = device_get_softc(dev); 219 int k = 0; 220 221 IICBB_SETSCL(device_get_parent(dev), val); 222 DELAY(sc->udelay); 223 224 while (val && !I2C_GETSCL(dev) && k++ < timeout) { 225 IICBB_SETSCL(device_get_parent(dev), val); 226 DELAY(sc->udelay); 227 } 228 229 return; 230 } 231 232 static void 233 iicbb_one(device_t dev, int timeout) 234 { 235 struct iicbb_softc *sc = device_get_softc(dev); 236 237 I2C_SET(sc,dev,0,1); 238 I2C_SET(sc,dev,1,1); 239 I2C_SET(sc,dev,0,1); 240 return; 241 } 242 243 static void 244 iicbb_zero(device_t dev, int timeout) 245 { 246 struct iicbb_softc *sc = device_get_softc(dev); 247 248 I2C_SET(sc,dev,0,0); 249 I2C_SET(sc,dev,1,0); 250 I2C_SET(sc,dev,0,0); 251 return; 252 } 253 254 /* 255 * Waiting for ACKNOWLEDGE. 256 * 257 * When a chip is being addressed or has received data it will issue an 258 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line 259 * (set it to high level) and then release the CLOCK line. 260 * Now it must wait for the SLAVE to pull the DATA line low. 261 * Actually on the bus this looks like a START condition so nothing happens 262 * because of the fact that the IC's that have not been addressed are doing 263 * nothing. 264 * 265 * When the SLAVE has pulled this line low the MASTER will take the CLOCK 266 * line low and then the SLAVE will release the SDA (data) line. 267 */ 268 static int 269 iicbb_ack(device_t dev, int timeout) 270 { 271 struct iicbb_softc *sc = device_get_softc(dev); 272 int noack; 273 int k = 0; 274 275 I2C_SET(sc,dev,0,1); 276 I2C_SET(sc,dev,1,1); 277 do { 278 noack = I2C_GETSDA(dev); 279 if (!noack) 280 break; 281 DELAY(1); 282 k++; 283 } while (k < timeout); 284 285 I2C_SET(sc,dev,0,1); 286 I2C_DEBUG(kprintf("%c ",noack?'-':'+')); 287 288 return (noack); 289 } 290 291 static void 292 iicbb_sendbyte(device_t dev, u_char data, int timeout) 293 { 294 int i; 295 296 for (i=7; i>=0; i--) { 297 if (data&(1<<i)) { 298 iicbb_one(dev, timeout); 299 } else { 300 iicbb_zero(dev, timeout); 301 } 302 } 303 I2C_DEBUG(kprintf("w%02x",(int)data)); 304 return; 305 } 306 307 static u_char 308 iicbb_readbyte(device_t dev, int last, int timeout) 309 { 310 struct iicbb_softc *sc = device_get_softc(dev); 311 int i; 312 unsigned char data=0; 313 314 I2C_SET(sc,dev,0,1); 315 for (i=7; i>=0; i--) 316 { 317 I2C_SET(sc,dev,1,1); 318 if (I2C_GETSDA(dev)) 319 data |= (1<<i); 320 I2C_SET(sc,dev,0,1); 321 } 322 if (last) { 323 iicbb_one(dev, timeout); 324 } else { 325 iicbb_zero(dev, timeout); 326 } 327 I2C_DEBUG(kprintf("r%02x%c ",(int)data,last?'-':'+')); 328 return data; 329 } 330 331 static int 332 iicbb_callback(device_t dev, int index, caddr_t data) 333 { 334 return (IICBB_CALLBACK(device_get_parent(dev), index, data)); 335 } 336 337 static int 338 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr) 339 { 340 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr)); 341 } 342 343 static int 344 iicbb_start(device_t dev, u_char slave, int timeout) 345 { 346 struct iicbb_softc *sc = device_get_softc(dev); 347 int error; 348 349 I2C_DEBUG(kprintf("<")); 350 351 I2C_SET(sc,dev,1,1); 352 I2C_SET(sc,dev,1,0); 353 I2C_SET(sc,dev,0,0); 354 355 /* send address */ 356 iicbb_sendbyte(dev, slave, timeout); 357 358 /* check for ack */ 359 if (iicbb_ack(dev, timeout)) { 360 error = IIC_ENOACK; 361 goto error; 362 } 363 364 return(0); 365 366 error: 367 iicbb_stop(dev); 368 return (error); 369 } 370 371 static int 372 iicbb_stop(device_t dev) 373 { 374 struct iicbb_softc *sc = device_get_softc(dev); 375 376 I2C_SET(sc,dev,0,0); 377 I2C_SET(sc,dev,1,0); 378 I2C_SET(sc,dev,1,1); 379 I2C_DEBUG(kprintf(">")); 380 I2C_DEBUG(kprintf("\n")); 381 return (0); 382 } 383 384 static int 385 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout) 386 { 387 int bytes, error = 0; 388 389 bytes = 0; 390 while (len) { 391 /* send byte */ 392 iicbb_sendbyte(dev,(u_char)*buf++, timeout); 393 394 /* check for ack */ 395 if (iicbb_ack(dev, timeout)) { 396 error = IIC_ENOACK; 397 goto error; 398 } 399 bytes ++; 400 len --; 401 } 402 403 error: 404 *sent = bytes; 405 return (error); 406 } 407 408 static int 409 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay) 410 { 411 int bytes; 412 413 bytes = 0; 414 while (len) { 415 /* XXX should insert delay here */ 416 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay); 417 418 bytes ++; 419 len --; 420 } 421 422 *read = bytes; 423 return (0); 424 } 425 426 static int 427 iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs) 428 { 429 int error; 430 431 error = IICBB_PRE_XFER(device_get_parent(dev)); 432 if (error) 433 return (error); 434 435 error = iicbus_transfer_gen(dev, msgs, nmsgs); 436 437 IICBB_POST_XFER(device_get_parent(dev)); 438 return (error); 439 } 440 441 DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, NULL, NULL); 442 DRIVER_MODULE(iicbb, cxm_iic, iicbb_driver, iicbb_devclass, NULL, NULL); 443 DRIVER_MODULE(iicbb, intel_iic, iicbb_driver, iicbb_devclass, NULL, NULL); 444 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, NULL, NULL); 445 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, NULL, NULL); 446 447 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER); 448 MODULE_VERSION(iicbb, IICBB_MODVER); 449