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 <sys/param.h> 47 #include <sys/kernel.h> 48 #include <sys/systm.h> 49 #include <sys/module.h> 50 #include <sys/bus.h> 51 #include <sys/uio.h> 52 53 54 #include <dev/iicbus/iiconf.h> 55 #include <dev/iicbus/iicbus.h> 56 57 #include <dev/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_probe(device_t); 67 static int iicbb_attach(device_t); 68 static int iicbb_detach(device_t); 69 static int iicbb_print_child(device_t, 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, 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 78 static device_method_t iicbb_methods[] = { 79 /* device interface */ 80 DEVMETHOD(device_probe, iicbb_probe), 81 DEVMETHOD(device_attach, iicbb_attach), 82 DEVMETHOD(device_detach, iicbb_detach), 83 84 /* bus interface */ 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 96 { 0, 0 } 97 }; 98 99 driver_t iicbb_driver = { 100 "iicbb", 101 iicbb_methods, 102 sizeof(struct iicbb_softc), 103 }; 104 105 devclass_t iicbb_devclass; 106 107 static int 108 iicbb_probe(device_t dev) 109 { 110 device_set_desc(dev, "I2C bit-banging driver"); 111 112 return (0); 113 } 114 115 static int 116 iicbb_attach(device_t dev) 117 { 118 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 119 120 sc->iicbus = device_add_child(dev, "iicbus", -1); 121 if (!sc->iicbus) 122 return (ENXIO); 123 bus_generic_attach(dev); 124 125 return (0); 126 } 127 128 static int 129 iicbb_detach(device_t dev) 130 { 131 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 132 133 if (sc->iicbus) { 134 bus_generic_detach(dev); 135 device_delete_child(dev, sc->iicbus); 136 } 137 138 return (0); 139 } 140 141 static int 142 iicbb_print_child(device_t bus, device_t dev) 143 { 144 int error; 145 int retval = 0; 146 u_char oldaddr; 147 148 retval += bus_print_child_header(bus, dev); 149 /* retrieve the interface I2C address */ 150 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr); 151 if (error == IIC_ENOADDR) { 152 retval += printf(" on %s master-only\n", 153 device_get_nameunit(bus)); 154 } else { 155 /* restore the address */ 156 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL); 157 158 retval += printf(" on %s addr 0x%x\n", 159 device_get_nameunit(bus), oldaddr & 0xff); 160 } 161 162 return (retval); 163 } 164 165 #define IIC_DELAY 10 166 167 #define I2C_SETSDA(dev,val) do { \ 168 IICBB_SETSDA(device_get_parent(dev), val); \ 169 DELAY(IIC_DELAY); \ 170 } while (0) 171 172 #define I2C_SETSCL(dev,val) do { \ 173 iicbb_setscl(dev, val, 100); \ 174 } while (0) 175 176 #define I2C_SET(dev,ctrl,data) do { \ 177 I2C_SETSCL(dev, ctrl); \ 178 I2C_SETSDA(dev, data); \ 179 } while (0) 180 181 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev))) 182 183 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev))) 184 185 static int i2c_debug = 0; 186 #define I2C_DEBUG(x) do { \ 187 if (i2c_debug) (x); \ 188 } while (0) 189 190 #define I2C_LOG(format,args...) do { \ 191 printf(format, args); \ 192 } while (0) 193 194 static void 195 iicbb_setscl(device_t dev, int val, int timeout) 196 { 197 int k = 0; 198 199 IICBB_SETSCL(device_get_parent(dev), val); 200 DELAY(IIC_DELAY); 201 202 while (val && !I2C_GETSCL(dev) && k++ < timeout) { 203 IICBB_SETSCL(device_get_parent(dev), val); 204 DELAY(IIC_DELAY); 205 } 206 207 return; 208 } 209 210 static void 211 iicbb_one(device_t dev, int timeout) 212 { 213 I2C_SET(dev,0,1); 214 I2C_SET(dev,1,1); 215 I2C_SET(dev,0,1); 216 return; 217 } 218 219 static void 220 iicbb_zero(device_t dev, int timeout) 221 { 222 I2C_SET(dev,0,0); 223 I2C_SET(dev,1,0); 224 I2C_SET(dev,0,0); 225 return; 226 } 227 228 /* 229 * Waiting for ACKNOWLEDGE. 230 * 231 * When a chip is being addressed or has received data it will issue an 232 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line 233 * (set it to high level) and then release the CLOCK line. 234 * Now it must wait for the SLAVE to pull the DATA line low. 235 * Actually on the bus this looks like a START condition so nothing happens 236 * because of the fact that the IC's that have not been addressed are doing 237 * nothing. 238 * 239 * When the SLAVE has pulled this line low the MASTER will take the CLOCK 240 * line low and then the SLAVE will release the SDA (data) line. 241 */ 242 static int 243 iicbb_ack(device_t dev, int timeout) 244 { 245 int noack; 246 int k = 0; 247 248 I2C_SET(dev,0,1); 249 I2C_SET(dev,1,1); 250 do { 251 noack = I2C_GETSDA(dev); 252 if (!noack) 253 break; 254 DELAY(10); 255 k += 10; 256 } while (k < timeout); 257 258 I2C_SET(dev,0,1); 259 I2C_DEBUG(printf("%c ",noack?'-':'+')); 260 261 return (noack); 262 } 263 264 static void 265 iicbb_sendbyte(device_t dev, u_char data, int timeout) 266 { 267 int i; 268 269 for (i=7; i>=0; i--) { 270 if (data&(1<<i)) { 271 iicbb_one(dev, timeout); 272 } else { 273 iicbb_zero(dev, timeout); 274 } 275 } 276 I2C_DEBUG(printf("w%02x",(int)data)); 277 return; 278 } 279 280 static u_char 281 iicbb_readbyte(device_t dev, int last, int timeout) 282 { 283 int i; 284 unsigned char data=0; 285 286 I2C_SET(dev,0,1); 287 for (i=7; i>=0; i--) 288 { 289 I2C_SET(dev,1,1); 290 if (I2C_GETSDA(dev)) 291 data |= (1<<i); 292 I2C_SET(dev,0,1); 293 } 294 if (last) { 295 iicbb_one(dev, timeout); 296 } else { 297 iicbb_zero(dev, timeout); 298 } 299 I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+')); 300 return data; 301 } 302 303 static int 304 iicbb_callback(device_t dev, int index, caddr_t data) 305 { 306 return (IICBB_CALLBACK(device_get_parent(dev), index, data)); 307 } 308 309 static int 310 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr) 311 { 312 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr)); 313 } 314 315 static int 316 iicbb_start(device_t dev, u_char slave, int timeout) 317 { 318 int error; 319 320 I2C_DEBUG(printf("<")); 321 322 I2C_SET(dev,1,1); 323 I2C_SET(dev,1,0); 324 I2C_SET(dev,0,0); 325 326 /* send address */ 327 iicbb_sendbyte(dev, slave, timeout); 328 329 /* check for ack */ 330 if (iicbb_ack(dev, timeout)) { 331 error = IIC_ENOACK; 332 goto error; 333 } 334 335 return(0); 336 337 error: 338 iicbb_stop(dev); 339 return (error); 340 } 341 342 static int 343 iicbb_stop(device_t dev) 344 { 345 I2C_SET(dev,0,0); 346 I2C_SET(dev,1,0); 347 I2C_SET(dev,1,1); 348 I2C_DEBUG(printf(">")); 349 return (0); 350 } 351 352 static int 353 iicbb_write(device_t dev, char * buf, int len, int *sent, int timeout) 354 { 355 int bytes, error = 0; 356 357 bytes = 0; 358 while (len) { 359 /* send byte */ 360 iicbb_sendbyte(dev,(u_char)*buf++, timeout); 361 362 /* check for ack */ 363 if (iicbb_ack(dev, timeout)) { 364 error = IIC_ENOACK; 365 goto error; 366 } 367 bytes ++; 368 len --; 369 } 370 371 error: 372 *sent = bytes; 373 return (error); 374 } 375 376 static int 377 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay) 378 { 379 int bytes; 380 381 bytes = 0; 382 while (len) { 383 /* XXX should insert delay here */ 384 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay); 385 386 bytes ++; 387 len --; 388 } 389 390 *read = bytes; 391 return (0); 392 } 393 394 DRIVER_MODULE(iicbb, bktr, iicbb_driver, iicbb_devclass, 0, 0); 395 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0); 396 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0); 397 398 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER); 399 MODULE_VERSION(iicbb, IICBB_MODVER); 400