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