iicbb.c revision 40782
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 * $Id$ 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 * TODO: port Peter's generic bit-banging code <dufault@hda.com> 45 */ 46 47#include <sys/param.h> 48#include <sys/kernel.h> 49#include <sys/systm.h> 50#include <sys/module.h> 51#include <sys/bus.h> 52#include <sys/conf.h> 53#include <sys/buf.h> 54#include <sys/uio.h> 55#include <sys/malloc.h> 56 57#include <machine/clock.h> 58 59#include <dev/iicbus/iiconf.h> 60#include <dev/iicbus/iicbus.h> 61 62#include <dev/smbus/smbconf.h> 63 64#include "iicbus_if.h" 65#include "iicbb_if.h" 66 67struct iicbb_softc { 68 int dummy; 69}; 70 71static int iicbb_probe(device_t); 72static int iicbb_attach(device_t); 73static void iicbb_print_child(device_t, device_t); 74 75static int iicbb_callback(device_t, int, caddr_t); 76static int iicbb_start(device_t, u_char, int); 77static int iicbb_stop(device_t); 78static int iicbb_write(device_t, char *, int, int *, int); 79static int iicbb_read(device_t, char *, int, int *, int, int); 80static int iicbb_reset(device_t, u_char, u_char, u_char *); 81 82static device_method_t iicbb_methods[] = { 83 /* device interface */ 84 DEVMETHOD(device_probe, iicbb_probe), 85 DEVMETHOD(device_attach, iicbb_attach), 86 87 /* bus interface */ 88 DEVMETHOD(bus_print_child, iicbb_print_child), 89 90 /* iicbus interface */ 91 DEVMETHOD(iicbus_callback, iicbb_callback), 92 DEVMETHOD(iicbus_start, iicbb_start), 93 DEVMETHOD(iicbus_repeated_start, iicbb_start), 94 DEVMETHOD(iicbus_stop, iicbb_stop), 95 DEVMETHOD(iicbus_write, iicbb_write), 96 DEVMETHOD(iicbus_read, iicbb_read), 97 DEVMETHOD(iicbus_reset, iicbb_reset), 98 99 { 0, 0 } 100}; 101 102static driver_t iicbb_driver = { 103 "iicbb", 104 iicbb_methods, 105 DRIVER_TYPE_MISC, 106 sizeof(struct iicbb_softc), 107}; 108 109static devclass_t iicbb_devclass; 110 111static int iicbb_probe(device_t dev) 112{ 113 device_set_desc(dev, "I2C generic bit-banging driver"); 114 115 return (0); 116} 117 118static int iicbb_attach(device_t dev) 119{ 120 return (0); 121} 122 123static void 124iicbb_print_child(device_t bus, device_t dev) 125{ 126 int error; 127 u_char oldaddr; 128 129 /* retrieve the interface I2C address */ 130 error = IICBB_RESET(bus, IIC_FASTEST, 0, &oldaddr); 131 if (error == IIC_ENOADDR) { 132 printf(" on %s%d master-only", device_get_name(bus), 133 device_get_unit(bus)); 134 135 } else { 136 /* restore the address */ 137 IICBB_RESET(bus, IIC_FASTEST, oldaddr, NULL); 138 139 printf(" on %s%d addr 0x%x", device_get_name(bus), 140 device_get_unit(bus), oldaddr & 0xff); 141 } 142 143 return; 144} 145 146#define I2C_SET(dev,ctrl,data) \ 147 IICBB_SETLINES(device_get_parent(dev), ctrl, data) 148 149#define I2C_GET(dev) (IICBB_GETDATALINE(device_get_parent(dev))) 150 151static int i2c_debug = 0; 152#define I2C_DEBUG(x) if (i2c_debug) (x) 153 154static void iicbb_one(device_t dev) 155{ 156 I2C_SET(dev,0,1); 157 I2C_SET(dev,1,1); 158 I2C_SET(dev,0,1); 159 return; 160} 161 162static void iicbb_zero(device_t dev) 163{ 164 I2C_SET(dev,0,0); 165 I2C_SET(dev,1,0); 166 I2C_SET(dev,0,0); 167 return; 168} 169 170/* 171 * Waiting for ACKNOWLEDGE. 172 * 173 * When a chip is being addressed or has received data it will issue an 174 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line 175 * (set it to high level) and then release the CLOCK line. 176 * Now it must wait for the SLAVE to pull the DATA line low. 177 * Actually on the bus this looks like a START condition so nothing happens 178 * because of the fact that the IC's that have not been addressed are doing 179 * nothing. 180 * 181 * When the SLAVE has pulled this line low the MASTER will take the CLOCK 182 * line low and then the SLAVE will release the SDA (data) line. 183 */ 184static int iicbb_ack(device_t dev, int timeout) 185{ 186 int noack; 187 int k = timeout/10; 188 189 I2C_SET(dev,0,1); 190 I2C_SET(dev,1,1); 191 192 do { 193 noack = I2C_GET(dev); 194 if (!noack) 195 break; 196 DELAY(10); /* XXX wait 10us */ 197 } while (k--); 198 199 I2C_SET(dev,0,1); 200 I2C_DEBUG(printf("%c ",noack?'-':'+')); 201 202 return (noack); 203} 204 205static void iicbb_sendbyte(device_t dev, u_char data) 206{ 207 int i; 208 209 I2C_SET(dev,0,0); 210 for (i=7; i>=0; i--) 211 (data&(1<<i)) ? iicbb_one(dev) : iicbb_zero(dev); 212 I2C_DEBUG(printf("w%02x",(int)data)); 213 return; 214} 215 216static u_char iicbb_readbyte(device_t dev, int last) 217{ 218 int i; 219 unsigned char data=0; 220 221 I2C_SET(dev,0,1); 222 for (i=7; i>=0; i--) 223 { 224 I2C_SET(dev,1,1); 225 if (I2C_GET(dev)) 226 data |= (1<<i); 227 I2C_SET(dev,0,1); 228 } 229 last ? iicbb_one(dev) : iicbb_zero(dev); 230 I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+')); 231 return data; 232} 233 234static int iicbb_callback(device_t dev, int index, caddr_t data) 235{ 236 return (IICBB_CALLBACK(device_get_parent(dev), index, data)); 237} 238 239static int iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr) 240{ 241 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr)); 242} 243 244static int iicbb_start(device_t dev, u_char slave, int timeout) 245{ 246 int error; 247 248 I2C_DEBUG(printf("<")); 249 250 I2C_SET(dev,0,1); 251 I2C_SET(dev,1,1); 252 I2C_SET(dev,1,0); 253 I2C_SET(dev,0,0); 254 255 /* send address */ 256 iicbb_sendbyte(dev, slave); 257 258 /* check for ack */ 259 if (iicbb_ack(dev, timeout)) { 260 error = IIC_ENOACK; 261 goto error; 262 } 263 264 return(0); 265 266error: 267 iicbb_stop(dev); 268 return (error); 269} 270 271static int iicbb_stop(device_t dev) 272{ 273 I2C_SET(dev,0,0); 274 I2C_SET(dev,1,0); 275 I2C_SET(dev,1,1); 276 I2C_DEBUG(printf(">")); 277 return (0); 278} 279 280static int iicbb_write(device_t dev, char * buf, int len, int *sent, 281 int timeout) 282{ 283 int bytes, error = 0; 284 285 bytes = 0; 286 while (len) { 287 /* send byte */ 288 iicbb_sendbyte(dev,(u_char)*buf++); 289 290 /* check for ack */ 291 if (iicbb_ack(dev, timeout)) { 292 error = IIC_ENOACK; 293 goto error; 294 } 295 bytes ++; 296 len --; 297 } 298 299error: 300 *sent = bytes; 301 return (error); 302} 303 304static int iicbb_read(device_t dev, char * buf, int len, int *read, 305 int last, int delay) 306{ 307 int bytes; 308 309 bytes = 0; 310 while (len) { 311 /* XXX should insert delay here */ 312 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? 1 : 0); 313 314 bytes ++; 315 len --; 316 } 317 318 *read = bytes; 319 return (0); 320} 321 322DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0); 323DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0); 324