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: src/sys/dev/iicbus/iicbb.c,v 1.21 2009/02/10 22:50:23 imp 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 */ 46 47 #include <sys/param.h> 48 #include <sys/kernel.h> 49 #include <sys/systm.h> 50 #include <sys/module.h> 51 #include <sys/bus.h> 52 #include <sys/uio.h> 53 54 #include <bus/iicbus/iiconf.h> 55 #include <bus/iicbus/iicbus.h> 56 57 #include <bus/smbus/smbconf.h> 58 59 #include "iicbus_if.h" 60 #include "iicbb_if.h" 61 62 struct iicbb_softc { 63 device_t iicbus; 64 }; 65 66 static int iicbb_attach(device_t); 67 static void iicbb_child_detached(device_t, device_t); 68 static int iicbb_detach(device_t); 69 static int iicbb_print_child(device_t, device_t); 70 static int iicbb_probe(device_t); 71 72 static int iicbb_callback(device_t, int, caddr_t); 73 static int iicbb_start(device_t, u_char, int); 74 static int iicbb_stop(device_t); 75 static int iicbb_write(device_t, const char *, int, int *, int); 76 static int iicbb_read(device_t, char *, int, int *, int, int); 77 static int iicbb_reset(device_t, u_char, u_char, u_char *); 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, iicbus_transfer_gen), 98 99 { 0, 0 } 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 bus_generic_attach(dev); 127 128 return (0); 129 } 130 131 static int 132 iicbb_detach(device_t dev) 133 { 134 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 135 device_t child; 136 137 /* 138 * We need to save child because the detach indirectly causes 139 * sc->iicbus to be zeroed. Since we added the device 140 * unconditionally in iicbb_attach, we need to make sure we 141 * delete it here. See iicbb_child_detached. We need that 142 * callback in case newbus detached our children w/o detaching 143 * us (say iicbus is a module and unloaded w/o iicbb being 144 * unloaded). 145 */ 146 child = sc->iicbus; 147 bus_generic_detach(dev); 148 if (child) 149 device_delete_child(dev, child); 150 151 return (0); 152 } 153 154 static void 155 iicbb_child_detached( device_t dev, device_t child ) 156 { 157 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 158 159 if (child == sc->iicbus) 160 sc->iicbus = NULL; 161 } 162 163 static int 164 iicbb_print_child(device_t bus, device_t dev) 165 { 166 int error; 167 int retval = 0; 168 u_char oldaddr; 169 170 retval += bus_print_child_header(bus, dev); 171 /* retrieve the interface I2C address */ 172 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr); 173 if (error == IIC_ENOADDR) { 174 retval += kprintf(" on %s master-only\n", 175 device_get_nameunit(bus)); 176 } else { 177 /* restore the address */ 178 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL); 179 180 retval += kprintf(" on %s addr 0x%x\n", 181 device_get_nameunit(bus), oldaddr & 0xff); 182 } 183 184 return (retval); 185 } 186 187 #define IIC_DELAY 10 188 189 #define I2C_SETSDA(dev,val) do { \ 190 IICBB_SETSDA(device_get_parent(dev), val); \ 191 DELAY(IIC_DELAY); \ 192 } while (0) 193 194 #define I2C_SETSCL(dev,val) do { \ 195 iicbb_setscl(dev, val, 100); \ 196 } while (0) 197 198 #define I2C_SET(dev,ctrl,data) do { \ 199 I2C_SETSCL(dev, ctrl); \ 200 I2C_SETSDA(dev, data); \ 201 } while (0) 202 203 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev))) 204 205 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev))) 206 207 static int i2c_debug = 0; 208 #define I2C_DEBUG(x) do { \ 209 if (i2c_debug) (x); \ 210 } while (0) 211 212 #define I2C_LOG(format,args...) do { \ 213 kprintf(format, args); \ 214 } while (0) 215 216 static void 217 iicbb_setscl(device_t dev, int val, int timeout) 218 { 219 int k = 0; 220 221 IICBB_SETSCL(device_get_parent(dev), val); 222 DELAY(IIC_DELAY); 223 224 while (val && !I2C_GETSCL(dev) && k++ < timeout) { 225 IICBB_SETSCL(device_get_parent(dev), val); 226 DELAY(IIC_DELAY); 227 } 228 229 return; 230 } 231 232 static void 233 iicbb_one(device_t dev, int timeout) 234 { 235 I2C_SET(dev,0,1); 236 I2C_SET(dev,1,1); 237 I2C_SET(dev,0,1); 238 return; 239 } 240 241 static void 242 iicbb_zero(device_t dev, int timeout) 243 { 244 I2C_SET(dev,0,0); 245 I2C_SET(dev,1,0); 246 I2C_SET(dev,0,0); 247 return; 248 } 249 250 /* 251 * Waiting for ACKNOWLEDGE. 252 * 253 * When a chip is being addressed or has received data it will issue an 254 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line 255 * (set it to high level) and then release the CLOCK line. 256 * Now it must wait for the SLAVE to pull the DATA line low. 257 * Actually on the bus this looks like a START condition so nothing happens 258 * because of the fact that the IC's that have not been addressed are doing 259 * nothing. 260 * 261 * When the SLAVE has pulled this line low the MASTER will take the CLOCK 262 * line low and then the SLAVE will release the SDA (data) line. 263 */ 264 static int 265 iicbb_ack(device_t dev, int timeout) 266 { 267 int noack; 268 int k = 0; 269 270 I2C_SET(dev,0,1); 271 I2C_SET(dev,1,1); 272 do { 273 noack = I2C_GETSDA(dev); 274 if (!noack) 275 break; 276 DELAY(10); 277 k += 10; 278 } while (k < timeout); 279 280 I2C_SET(dev,0,1); 281 I2C_DEBUG(kprintf("%c ",noack?'-':'+')); 282 283 return (noack); 284 } 285 286 static void 287 iicbb_sendbyte(device_t dev, u_char data, int timeout) 288 { 289 int i; 290 291 for (i=7; i>=0; i--) { 292 if (data&(1<<i)) { 293 iicbb_one(dev, timeout); 294 } else { 295 iicbb_zero(dev, timeout); 296 } 297 } 298 I2C_DEBUG(kprintf("w%02x",(int)data)); 299 return; 300 } 301 302 static u_char 303 iicbb_readbyte(device_t dev, int last, int timeout) 304 { 305 int i; 306 unsigned char data=0; 307 308 I2C_SET(dev,0,1); 309 for (i=7; i>=0; i--) 310 { 311 I2C_SET(dev,1,1); 312 if (I2C_GETSDA(dev)) 313 data |= (1<<i); 314 I2C_SET(dev,0,1); 315 } 316 if (last) { 317 iicbb_one(dev, timeout); 318 } else { 319 iicbb_zero(dev, timeout); 320 } 321 I2C_DEBUG(kprintf("r%02x%c ",(int)data,last?'-':'+')); 322 return data; 323 } 324 325 static int 326 iicbb_callback(device_t dev, int index, caddr_t data) 327 { 328 return (IICBB_CALLBACK(device_get_parent(dev), index, data)); 329 } 330 331 static int 332 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr) 333 { 334 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr)); 335 } 336 337 static int 338 iicbb_start(device_t dev, u_char slave, int timeout) 339 { 340 int error; 341 342 I2C_DEBUG(kprintf("<")); 343 344 I2C_SET(dev,1,1); 345 I2C_SET(dev,1,0); 346 I2C_SET(dev,0,0); 347 348 /* send address */ 349 iicbb_sendbyte(dev, slave, timeout); 350 351 /* check for ack */ 352 if (iicbb_ack(dev, timeout)) { 353 error = IIC_ENOACK; 354 goto error; 355 } 356 357 return(0); 358 359 error: 360 iicbb_stop(dev); 361 return (error); 362 } 363 364 static int 365 iicbb_stop(device_t dev) 366 { 367 I2C_SET(dev,0,0); 368 I2C_SET(dev,1,0); 369 I2C_SET(dev,1,1); 370 I2C_DEBUG(kprintf(">")); 371 return (0); 372 } 373 374 static int 375 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout) 376 { 377 int bytes, error = 0; 378 379 bytes = 0; 380 while (len) { 381 /* send byte */ 382 iicbb_sendbyte(dev,(u_char)*buf++, timeout); 383 384 /* check for ack */ 385 if (iicbb_ack(dev, timeout)) { 386 error = IIC_ENOACK; 387 goto error; 388 } 389 bytes ++; 390 len --; 391 } 392 393 error: 394 *sent = bytes; 395 return (error); 396 } 397 398 static int 399 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay) 400 { 401 int bytes; 402 403 bytes = 0; 404 while (len) { 405 /* XXX should insert delay here */ 406 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay); 407 408 bytes ++; 409 len --; 410 } 411 412 *read = bytes; 413 return (0); 414 } 415 416 DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0); 417 DRIVER_MODULE(iicbb, cxm_iic, iicbb_driver, iicbb_devclass, 0, 0); 418 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0); 419 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0); 420 421 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER); 422 MODULE_VERSION(iicbb, IICBB_MODVER); 423