common/soft_i2c.c

   1 /*
   2  * (C) Copyright 2001, 2002
   3  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  *
  23  * This has been changed substantially by Gerald Van Baren, Custom IDEAS,
  24  * vanbaren@cideas.com.  It was heavily influenced by LiMon, written by
  25  * Neil Russell.
  26  */
  27
  28 #include <common.h>
  29 #ifdef  CONFIG_MPC8260                  /* only valid for MPC8260 */
  30 #include <ioports.h>
  31 #endif
  32 #ifdef CONFIG_AT91RM9200DK              /* need this for the at91rm9200dk */
  33 #include <asm/io.h>
  34 #include <asm/arch/hardware.h>
  35 #endif
  36 #ifdef  CONFIG_IXP425                   /* only valid for IXP425 */
  37 #include <asm/arch/ixp425.h>
  38 #endif
  39 #include <i2c.h>
  40
  41 #if defined(CONFIG_SOFT_I2C)
  42
  43 /* #define      DEBUG_I2C       */
  44
  45 #ifdef DEBUG_I2C
  46 DECLARE_GLOBAL_DATA_PTR;
  47 #endif
  48
  49
  50 /*-----------------------------------------------------------------------
  51  * Definitions
  52  */
  53
  54 #define RETRIES         0
  55
  56
  57 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
  58 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
  59
  60
  61 #ifdef DEBUG_I2C
  62 #define PRINTD(fmt,args...)     do {    \
  63         if (gd->have_console)           \
  64                 printf (fmt ,##args);   \
  65         } while (0)
  66 #else
  67 #define PRINTD(fmt,args...)
  68 #endif
  69
  70 /*-----------------------------------------------------------------------
  71  * Local functions
  72  */
  73 static void  send_reset (void);
  74 static void  send_start (void);
  75 static void  send_stop  (void);
  76 static void  send_ack   (int);
  77 static int   write_byte (uchar byte);
  78 static uchar read_byte  (int);
  79
  80
  81 /*-----------------------------------------------------------------------
  82  * Send a reset sequence consisting of 9 clocks with the data signal high
  83  * to clock any confused device back into an idle state.  Also send a
  84  * <stop> at the end of the sequence for belts & suspenders.
  85  */
  86 static void send_reset(void)
  87 {
  88 #ifdef  CONFIG_MPC8260
  89         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
  90 #endif
  91 #ifdef  CONFIG_8xx
  92         volatile immap_t *immr = (immap_t *)CFG_IMMR;
  93 #endif
  94         int j;
  95
  96         I2C_SCL(1);
  97         I2C_SDA(1);
  98 #ifdef  I2C_INIT
  99         I2C_INIT;
 100 #endif
 101         I2C_TRISTATE;
 102         for(j = 0; j < 9; j++) {
 103                 I2C_SCL(0);
 104                 I2C_DELAY;
 105                 I2C_DELAY;
 106                 I2C_SCL(1);
 107                 I2C_DELAY;
 108                 I2C_DELAY;
 109         }
 110         send_stop();
 111         I2C_TRISTATE;
 112 }
 113
 114 /*-----------------------------------------------------------------------
 115  * START: High -> Low on SDA while SCL is High
 116  */
 117 static void send_start(void)
 118 {
 119 #ifdef  CONFIG_MPC8260
 120         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
 121 #endif
 122 #ifdef  CONFIG_8xx
 123         volatile immap_t *immr = (immap_t *)CFG_IMMR;
 124 #endif
 125
 126         I2C_DELAY;
 127         I2C_SDA(1);
 128         I2C_ACTIVE;
 129         I2C_DELAY;
 130         I2C_SCL(1);
 131         I2C_DELAY;
 132         I2C_SDA(0);
 133         I2C_DELAY;
 134 }
 135
 136 /*-----------------------------------------------------------------------
 137  * STOP: Low -> High on SDA while SCL is High
 138  */
 139 static void send_stop(void)
 140 {
 141 #ifdef  CONFIG_MPC8260
 142         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
 143 #endif
 144 #ifdef  CONFIG_8xx
 145         volatile immap_t *immr = (immap_t *)CFG_IMMR;
 146 #endif
 147
 148         I2C_SCL(0);
 149         I2C_DELAY;
 150         I2C_SDA(0);
 151         I2C_ACTIVE;
 152         I2C_DELAY;
 153         I2C_SCL(1);
 154         I2C_DELAY;
 155         I2C_SDA(1);
 156         I2C_DELAY;
 157         I2C_TRISTATE;
 158 }
 159
 160
 161 /*-----------------------------------------------------------------------
 162  * ack should be I2C_ACK or I2C_NOACK
 163  */
 164 static void send_ack(int ack)
 165 {
 166 #ifdef  CONFIG_MPC8260
 167         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
 168 #endif
 169 #ifdef  CONFIG_8xx
 170         volatile immap_t *immr = (immap_t *)CFG_IMMR;
 171 #endif
 172
 173         I2C_SCL(0);
 174         I2C_DELAY;
 175         I2C_ACTIVE;
 176         I2C_SDA(ack);
 177         I2C_DELAY;
 178         I2C_SCL(1);
 179         I2C_DELAY;
 180         I2C_DELAY;
 181         I2C_SCL(0);
 182         I2C_DELAY;
 183 }
 184
 185
 186 /*-----------------------------------------------------------------------
 187  * Send 8 bits and look for an acknowledgement.
 188  */
 189 static int write_byte(uchar data)
 190 {
 191 #ifdef  CONFIG_MPC8260
 192         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
 193 #endif
 194 #ifdef  CONFIG_8xx
 195         volatile immap_t *immr = (immap_t *)CFG_IMMR;
 196 #endif
 197         int j;
 198         int nack;
 199
 200         I2C_ACTIVE;
 201         for(j = 0; j < 8; j++) {
 202                 I2C_SCL(0);
 203                 I2C_DELAY;
 204                 I2C_SDA(data & 0x80);
 205                 I2C_DELAY;
 206                 I2C_SCL(1);
 207                 I2C_DELAY;
 208                 I2C_DELAY;
 209
 210                 data <<= 1;
 211         }
 212
 213         /*
 214          * Look for an <ACK>(negative logic) and return it.
 215          */
 216         I2C_SCL(0);
 217         I2C_DELAY;
 218         I2C_SDA(1);
 219         I2C_TRISTATE;
 220         I2C_DELAY;
 221         I2C_SCL(1);
 222         I2C_DELAY;
 223         I2C_DELAY;
 224         nack = I2C_READ;
 225         I2C_SCL(0);
 226         I2C_DELAY;
 227         I2C_ACTIVE;
 228
 229         return(nack);   /* not a nack is an ack */
 230 }
 231
 232
 233 /*-----------------------------------------------------------------------
 234  * if ack == I2C_ACK, ACK the byte so can continue reading, else
 235  * send I2C_NOACK to end the read.
 236  */
 237 static uchar read_byte(int ack)
 238 {
 239 #ifdef  CONFIG_MPC8260
 240         volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, I2C_PORT);
 241 #endif
 242 #ifdef  CONFIG_8xx
 243         volatile immap_t *immr = (immap_t *)CFG_IMMR;
 244 #endif
 245         int  data;
 246         int  j;
 247
 248         /*
 249          * Read 8 bits, MSB first.
 250          */
 251         I2C_TRISTATE;
 252         data = 0;
 253         for(j = 0; j < 8; j++) {
 254                 I2C_SCL(0);
 255                 I2C_DELAY;
 256                 I2C_SCL(1);
 257                 I2C_DELAY;
 258                 data <<= 1;
 259                 data |= I2C_READ;
 260                 I2C_DELAY;
 261         }
 262         send_ack(ack);
 263
 264         return(data);
 265 }
 266
 267 /*=====================================================================*/
 268 /*                         Public Functions                            */
 269 /*=====================================================================*/
 270
 271 /*-----------------------------------------------------------------------
 272  * Initialization
 273  */
 274 void i2c_init (int speed, int slaveaddr)
 275 {
 276         /*
 277          * WARNING: Do NOT save speed in a static variable: if the
 278          * I2C routines are called before RAM is initialized (to read
 279          * the DIMM SPD, for instance), RAM won't be usable and your
 280          * system will crash.
 281          */
 282         send_reset ();
 283 }
 284
 285 /*-----------------------------------------------------------------------
 286  * Probe to see if a chip is present.  Also good for checking for the
 287  * completion of EEPROM writes since the chip stops responding until
 288  * the write completes (typically 10mSec).
 289  */
 290 int i2c_probe(uchar addr)
 291 {
 292         int rc;
 293
 294         /*
 295          * perform 1 byte write transaction with just address byte
 296          * (fake write)
 297          */
 298         send_start();
 299         rc = write_byte ((addr << 1) | 0);
 300         send_stop();
 301
 302         return (rc ? 1 : 0);
 303 }
 304
 305 /*-----------------------------------------------------------------------
 306  * Read bytes
 307  */
 308 int  i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
 309 {
 310         int shift;
 311         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
 312                 chip, addr, alen, buffer, len);
 313
 314 #ifdef CFG_I2C_EEPROM_ADDR_OVERFLOW
 315         /*
 316          * EEPROM chips that implement "address overflow" are ones
 317          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 318          * address and the extra bits end up in the "chip address"
 319          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 320          * four 256 byte chips.
 321          *
 322          * Note that we consider the length of the address field to
 323          * still be one byte because the extra address bits are
 324          * hidden in the chip address.
 325          */
 326         chip |= ((addr >> (alen * 8)) & CFG_I2C_EEPROM_ADDR_OVERFLOW);
 327
 328         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
 329                 chip, addr);
 330 #endif
 331
 332         /*
 333          * Do the addressing portion of a write cycle to set the
 334          * chip's address pointer.  If the address length is zero,
 335          * don't do the normal write cycle to set the address pointer,
 336          * there is no address pointer in this chip.
 337          */
 338         send_start();
 339         if(alen > 0) {
 340                 if(write_byte(chip << 1)) {     /* write cycle */
 341                         send_stop();
 342                         PRINTD("i2c_read, no chip responded %02X\n", chip);
 343                         return(1);
 344                 }
 345                 shift = (alen-1) * 8;
 346                 while(alen-- > 0) {
 347                         if(write_byte(addr >> shift)) {
 348                                 PRINTD("i2c_read, address not <ACK>ed\n");
 349                                 return(1);
 350                         }
 351                         shift -= 8;
 352                 }
 353                 send_stop();    /* reportedly some chips need a full stop */
 354                 send_start();
 355         }
 356         /*
 357          * Send the chip address again, this time for a read cycle.
 358          * Then read the data.  On the last byte, we do a NACK instead
 359          * of an ACK(len == 0) to terminate the read.
 360          */
 361         write_byte((chip << 1) | 1);    /* read cycle */
 362         while(len-- > 0) {
 363                 *buffer++ = read_byte(len == 0);
 364         }
 365         send_stop();
 366         return(0);
 367 }
 368
 369 /*-----------------------------------------------------------------------
 370  * Write bytes
 371  */
 372 int  i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
 373 {
 374         int shift, failures = 0;
 375
 376         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
 377                 chip, addr, alen, buffer, len);
 378
 379         send_start();
 380         if(write_byte(chip << 1)) {     /* write cycle */
 381                 send_stop();
 382                 PRINTD("i2c_write, no chip responded %02X\n", chip);
 383                 return(1);
 384         }
 385         shift = (alen-1) * 8;
 386         while(alen-- > 0) {
 387                 if(write_byte(addr >> shift)) {
 388                         PRINTD("i2c_write, address not <ACK>ed\n");
 389                         return(1);
 390                 }
 391                 shift -= 8;
 392         }
 393
 394         while(len-- > 0) {
 395                 if(write_byte(*buffer++)) {
 396                         failures++;
 397                 }
 398         }
 399         send_stop();
 400         return(failures);
 401 }
 402
 403 /*-----------------------------------------------------------------------
 404  * Read a register
 405  */
 406 uchar i2c_reg_read(uchar i2c_addr, uchar reg)
 407 {
 408         uchar buf;
 409
 410         i2c_read(i2c_addr, reg, 1, &buf, 1);
 411
 412         return(buf);
 413 }
 414
 415 /*-----------------------------------------------------------------------
 416  * Write a register
 417  */
 418 void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val)
 419 {
 420         i2c_write(i2c_addr, reg, 1, &val, 1);
 421 }
 422
 423
 424 #endif  /* CONFIG_SOFT_I2C */