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