1 /*- 2 * Copyright (c) 1998 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 1.6.2.2 2002/04/19 05:52:12 nsouch 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 * TODO: port Peter's generic bit-banging code <dufault@hda.com> 46 */ 47 48 #include <sys/param.h> 49 #include <sys/kernel.h> 50 #include <sys/systm.h> 51 #include <sys/module.h> 52 #include <sys/bus.h> 53 #include <sys/conf.h> 54 #include <sys/buf.h> 55 #include <sys/uio.h> 56 #include <sys/malloc.h> 57 58 #include <machine/clock.h> 59 60 #include "iiconf.h" 61 #include "iicbus.h" 62 63 #include <bus/smbus/smbconf.h> 64 65 #include "iicbus_if.h" 66 #include "iicbb_if.h" 67 68 struct iicbb_softc { 69 device_t iicbus; 70 }; 71 72 static int iicbb_attach(device_t); 73 static void iicbb_child_detached(device_t, device_t); 74 static int iicbb_detach(device_t); 75 static int iicbb_print_child(device_t, device_t); 76 static int iicbb_probe(device_t); 77 78 static int iicbb_callback(device_t, int, caddr_t); 79 static int iicbb_start(device_t, u_char, int); 80 static int iicbb_stop(device_t); 81 static int iicbb_write(device_t, const char *, int, int *, int); 82 static int iicbb_read(device_t, char *, int, int *, int, int); 83 static int iicbb_reset(device_t, u_char, u_char, u_char *); 84 85 static device_method_t iicbb_methods[] = { 86 /* device interface */ 87 DEVMETHOD(device_probe, iicbb_probe), 88 DEVMETHOD(device_attach, iicbb_attach), 89 DEVMETHOD(device_detach, iicbb_detach), 90 91 /* bus interface */ 92 DEVMETHOD(bus_child_detached, iicbb_child_detached), 93 DEVMETHOD(bus_print_child, iicbb_print_child), 94 95 /* iicbus interface */ 96 DEVMETHOD(iicbus_callback, iicbb_callback), 97 DEVMETHOD(iicbus_start, iicbb_start), 98 DEVMETHOD(iicbus_repeated_start, iicbb_start), 99 DEVMETHOD(iicbus_stop, iicbb_stop), 100 DEVMETHOD(iicbus_write, iicbb_write), 101 DEVMETHOD(iicbus_read, iicbb_read), 102 DEVMETHOD(iicbus_reset, iicbb_reset), 103 104 { 0, 0 } 105 }; 106 107 static driver_t iicbb_driver = { 108 "iicbb", 109 iicbb_methods, 110 sizeof(struct iicbb_softc), 111 }; 112 113 static devclass_t iicbb_devclass; 114 115 static int 116 iicbb_probe(device_t dev) 117 { 118 device_set_desc(dev, "I2C bit-banging driver"); 119 120 return (0); 121 } 122 123 static int 124 iicbb_attach(device_t dev) 125 { 126 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 127 128 sc->iicbus = device_add_child(dev, "iicbus", -1); 129 if (!sc->iicbus) 130 return (ENXIO); 131 bus_generic_attach(dev); 132 133 return (0); 134 } 135 136 static int 137 iicbb_detach(device_t dev) 138 { 139 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 140 device_t child; 141 142 /* 143 * We need to save child because the detach indirectly causes 144 * sc->iicbus to be zeroed. Since we added the device 145 * unconditionally in iicbb_attach, we need to make sure we 146 * delete it here. See iicbb_child_detached. We need that 147 * callback in case newbus detached our children w/o detaching 148 * us (say iicbus is a module and unloaded w/o iicbb being 149 * unloaded). 150 */ 151 child = sc->iicbus; 152 bus_generic_detach(dev); 153 if (child) 154 device_delete_child(dev, child); 155 156 return (0); 157 } 158 159 static void 160 iicbb_child_detached(device_t dev, device_t child) 161 { 162 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev); 163 164 if (child == sc->iicbus) 165 sc->iicbus = NULL; 166 } 167 168 static int 169 iicbb_print_child(device_t bus, device_t dev) 170 { 171 int error; 172 int retval = 0; 173 u_char oldaddr; 174 175 retval += bus_print_child_header(bus, dev); 176 /* retrieve the interface I2C address */ 177 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr); 178 if (error == IIC_ENOADDR) { 179 retval += kprintf(" on %s master-only\n", 180 device_get_nameunit(bus)); 181 } else { 182 /* restore the address */ 183 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL); 184 185 retval += kprintf(" on %s addr 0x%x\n", 186 device_get_nameunit(bus), oldaddr & 0xff); 187 } 188 189 return (retval); 190 } 191 192 #define I2C_SET(dev,ctrl,data) \ 193 IICBB_SETLINES(device_get_parent(dev), ctrl, data) 194 195 #define I2C_GET(dev) (IICBB_GETDATALINE(device_get_parent(dev))) 196 197 static int i2c_debug = 0; 198 #define I2C_DEBUG(x) if (i2c_debug) (x) 199 200 static void 201 iicbb_one(device_t dev) 202 { 203 I2C_SET(dev,0,1); 204 I2C_SET(dev,1,1); 205 I2C_SET(dev,0,1); 206 return; 207 } 208 209 static void 210 iicbb_zero(device_t dev) 211 { 212 I2C_SET(dev,0,0); 213 I2C_SET(dev,1,0); 214 I2C_SET(dev,0,0); 215 return; 216 } 217 218 /* 219 * Waiting for ACKNOWLEDGE. 220 * 221 * When a chip is being addressed or has received data it will issue an 222 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line 223 * (set it to high level) and then release the CLOCK line. 224 * Now it must wait for the SLAVE to pull the DATA line low. 225 * Actually on the bus this looks like a START condition so nothing happens 226 * because of the fact that the IC's that have not been addressed are doing 227 * nothing. 228 * 229 * When the SLAVE has pulled this line low the MASTER will take the CLOCK 230 * line low and then the SLAVE will release the SDA (data) line. 231 */ 232 static int 233 iicbb_ack(device_t dev, int timeout) 234 { 235 int noack; 236 int k = timeout/10; 237 238 I2C_SET(dev,0,1); 239 I2C_SET(dev,1,1); 240 241 do { 242 noack = I2C_GET(dev); 243 if (!noack) 244 break; 245 DELAY(10); /* XXX wait 10us */ 246 } while (k--); 247 248 I2C_SET(dev,0,1); 249 I2C_DEBUG(kprintf("%c ",noack?'-':'+')); 250 251 return (noack); 252 } 253 254 static void 255 iicbb_sendbyte(device_t dev, u_char data) 256 { 257 int i; 258 259 I2C_SET(dev,0,0); 260 for (i=7; i>=0; i--) 261 (data&(1<<i)) ? iicbb_one(dev) : iicbb_zero(dev); 262 I2C_DEBUG(kprintf("w%02x",(int)data)); 263 return; 264 } 265 266 static u_char 267 iicbb_readbyte(device_t dev, int last) 268 { 269 int i; 270 unsigned char data=0; 271 272 I2C_SET(dev,0,1); 273 for (i=7; i>=0; i--) 274 { 275 I2C_SET(dev,1,1); 276 if (I2C_GET(dev)) 277 data |= (1<<i); 278 I2C_SET(dev,0,1); 279 } 280 last ? iicbb_one(dev) : iicbb_zero(dev); 281 I2C_DEBUG(kprintf("r%02x%c ",(int)data,last?'-':'+')); 282 return data; 283 } 284 285 static int 286 iicbb_callback(device_t dev, int index, caddr_t data) 287 { 288 return (IICBB_CALLBACK(device_get_parent(dev), index, data)); 289 } 290 291 static int 292 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr) 293 { 294 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr)); 295 } 296 297 static int 298 iicbb_start(device_t dev, u_char slave, int timeout) 299 { 300 int error; 301 302 I2C_DEBUG(kprintf("<")); 303 304 I2C_SET(dev,0,1); 305 I2C_SET(dev,1,1); 306 I2C_SET(dev,1,0); 307 I2C_SET(dev,0,0); 308 309 /* send address */ 310 iicbb_sendbyte(dev, slave); 311 312 /* check for ack */ 313 if (iicbb_ack(dev, timeout)) { 314 error = IIC_ENOACK; 315 goto error; 316 } 317 318 return(0); 319 320 error: 321 iicbb_stop(dev); 322 return (error); 323 } 324 325 static int 326 iicbb_stop(device_t dev) 327 { 328 I2C_SET(dev,0,0); 329 I2C_SET(dev,1,0); 330 I2C_SET(dev,1,1); 331 I2C_DEBUG(kprintf(">")); 332 return (0); 333 } 334 335 static int 336 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout) 337 { 338 int bytes, error = 0; 339 340 bytes = 0; 341 while (len) { 342 /* send byte */ 343 iicbb_sendbyte(dev,(u_char)*buf++); 344 345 /* check for ack */ 346 if (iicbb_ack(dev, timeout)) { 347 error = IIC_ENOACK; 348 goto error; 349 } 350 bytes ++; 351 len --; 352 } 353 354 error: 355 *sent = bytes; 356 return (error); 357 } 358 359 static int 360 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay) 361 { 362 int bytes; 363 364 bytes = 0; 365 while (len) { 366 /* XXX should insert delay here */ 367 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0); 368 369 bytes ++; 370 len --; 371 } 372 373 *read = bytes; 374 return (0); 375 } 376 377 DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0); 378 DRIVER_MODULE(iicbb, cxm_iic, iicbb_driver, iicbb_devclass, 0, 0); 379 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0); 380 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0); 381