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