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 * $FreeBSD$ 27 * 28 */ 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 static driver_t iicbb_driver = { 100 "iicbb", 101 iicbb_methods, 102 sizeof(struct iicbb_softc), 103 }; 104 105 static devclass_t iicbb_devclass; 106 107 static int iicbb_probe(device_t dev) 108 { 109 device_set_desc(dev, "I2C bit-banging driver"); 110 111 return (0); 112 } 113 114 static int iicbb_attach(device_t dev) 115 { 116 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 117 118 bzero(sc, sizeof(struct iicbb_softc)); 119 120 sc->iicbus = device_add_child(dev, "iicbus", -1); 121 122 if (!sc->iicbus) 123 return (ENXIO); 124 125 bus_generic_attach(dev); 126 127 return (0); 128 } 129 130 static int iicbb_detach(device_t dev) 131 { 132 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 133 134 if (sc->iicbus) { 135 bus_generic_detach(dev); 136 device_delete_child(dev, sc->iicbus); 137 } 138 139 return (0); 140 } 141 142 static int 143 iicbb_print_child(device_t bus, device_t dev) 144 { 145 int error; 146 int retval = 0; 147 u_char oldaddr; 148 149 retval += bus_print_child_header(bus, dev); 150 /* retrieve the interface I2C address */ 151 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr); 152 if (error == IIC_ENOADDR) { 153 retval += printf(" on %s master-only\n", 154 device_get_nameunit(bus)); 155 } else { 156 /* restore the address */ 157 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL); 158 159 retval += printf(" on %s addr 0x%x\n", 160 device_get_nameunit(bus), oldaddr & 0xff); 161 } 162 163 return (retval); 164 } 165 166 #define IIC_DELAY 10 167 168 #define I2C_SETSDA(dev,val) do { \ 169 IICBB_SETSDA(device_get_parent(dev), val); \ 170 DELAY(IIC_DELAY); \ 171 } while (0) 172 173 #define I2C_SETSCL(dev,val) do { \ 174 iicbb_setscl(dev, val, 100); \ 175 } while (0) 176 177 #define I2C_SET(dev,ctrl,data) do { \ 178 I2C_SETSCL(dev, ctrl); \ 179 I2C_SETSDA(dev, data); \ 180 } while (0) 181 182 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev))) 183 184 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev))) 185 186 static int i2c_debug = 0; 187 #define I2C_DEBUG(x) do { \ 188 if (i2c_debug) (x); \ 189 } while (0) 190 191 #define I2C_LOG(format,args...) do { \ 192 printf(format, args); \ 193 } while (0) 194 195 static void 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 iicbb_one(device_t dev, int timeout) 211 { 212 I2C_SET(dev,0,1); 213 I2C_SET(dev,1,1); 214 I2C_SET(dev,0,1); 215 return; 216 } 217 218 static void iicbb_zero(device_t dev, int timeout) 219 { 220 I2C_SET(dev,0,0); 221 I2C_SET(dev,1,0); 222 I2C_SET(dev,0,0); 223 return; 224 } 225 226 /* 227 * Waiting for ACKNOWLEDGE. 228 * 229 * When a chip is being addressed or has received data it will issue an 230 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line 231 * (set it to high level) and then release the CLOCK line. 232 * Now it must wait for the SLAVE to pull the DATA line low. 233 * Actually on the bus this looks like a START condition so nothing happens 234 * because of the fact that the IC's that have not been addressed are doing 235 * nothing. 236 * 237 * When the SLAVE has pulled this line low the MASTER will take the CLOCK 238 * line low and then the SLAVE will release the SDA (data) line. 239 */ 240 static int iicbb_ack(device_t dev, int timeout) 241 { 242 int noack; 243 int k = 0; 244 245 I2C_SET(dev,0,1); 246 I2C_SET(dev,1,1); 247 do { 248 noack = I2C_GETSDA(dev); 249 if (!noack) 250 break; 251 DELAY(10); 252 k += 10; 253 } while (k < timeout); 254 255 I2C_SET(dev,0,1); 256 I2C_DEBUG(printf("%c ",noack?'-':'+')); 257 258 return (noack); 259 } 260 261 static void iicbb_sendbyte(device_t dev, u_char data, int timeout) 262 { 263 int i; 264 265 for (i=7; i>=0; i--) { 266 if (data&(1<<i)) { 267 iicbb_one(dev, timeout); 268 } else { 269 iicbb_zero(dev, timeout); 270 } 271 } 272 I2C_DEBUG(printf("w%02x",(int)data)); 273 return; 274 } 275 276 static u_char iicbb_readbyte(device_t dev, int last, int timeout) 277 { 278 int i; 279 unsigned char data=0; 280 281 I2C_SET(dev,0,1); 282 for (i=7; i>=0; i--) 283 { 284 I2C_SET(dev,1,1); 285 if (I2C_GETSDA(dev)) 286 data |= (1<<i); 287 I2C_SET(dev,0,1); 288 } 289 if (last) { 290 iicbb_one(dev, timeout); 291 } else { 292 iicbb_zero(dev, timeout); 293 } 294 I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+')); 295 return data; 296 } 297 298 static int iicbb_callback(device_t dev, int index, caddr_t data) 299 { 300 return (IICBB_CALLBACK(device_get_parent(dev), index, data)); 301 } 302 303 static int iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr) 304 { 305 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr)); 306 } 307 308 static int iicbb_start(device_t dev, u_char slave, int timeout) 309 { 310 int error; 311 312 I2C_DEBUG(printf("<")); 313 314 I2C_SET(dev,1,1); 315 I2C_SET(dev,1,0); 316 I2C_SET(dev,0,0); 317 318 /* send address */ 319 iicbb_sendbyte(dev, slave, timeout); 320 321 /* check for ack */ 322 if (iicbb_ack(dev, timeout)) { 323 error = IIC_ENOACK; 324 goto error; 325 } 326 327 return(0); 328 329 error: 330 iicbb_stop(dev); 331 return (error); 332 } 333 334 static int iicbb_stop(device_t dev) 335 { 336 I2C_SET(dev,0,0); 337 I2C_SET(dev,1,0); 338 I2C_SET(dev,1,1); 339 I2C_DEBUG(printf(">")); 340 return (0); 341 } 342 343 static int iicbb_write(device_t dev, char * buf, int len, int *sent, 344 int timeout) 345 { 346 int bytes, error = 0; 347 348 bytes = 0; 349 while (len) { 350 /* send byte */ 351 iicbb_sendbyte(dev,(u_char)*buf++, timeout); 352 353 /* check for ack */ 354 if (iicbb_ack(dev, timeout)) { 355 error = IIC_ENOACK; 356 goto error; 357 } 358 bytes ++; 359 len --; 360 } 361 362 error: 363 *sent = bytes; 364 return (error); 365 } 366 367 static int iicbb_read(device_t dev, char * buf, int len, int *read, 368 int last, int delay) 369 { 370 int bytes; 371 372 bytes = 0; 373 while (len) { 374 /* XXX should insert delay here */ 375 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay); 376 377 bytes ++; 378 len --; 379 } 380 381 *read = bytes; 382 return (0); 383 } 384 385 DRIVER_MODULE(iicbb, bktr, iicbb_driver, iicbb_devclass, 0, 0); 386 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0); 387 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0); 388 389 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER); 390 MODULE_VERSION(iicbb, IICBB_MODVER); 391