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