drivers/i2c/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 #include <asm/io.h>
  32 #endif
  33 #ifdef  CONFIG_AT91RM9200               /* need this for the at91rm9200 */
  34 #include <asm/io.h>
  35 #include <asm/arch/hardware.h>
  36 #endif
  37 #ifdef CONFIG_AT91SAM9263               /* only valid for AT91SAM9263 */
  38 #include <asm/arch/at91_pmc.h>
  39 #include <asm/arch/gpio.h>
  40 #include <asm/arch/io.h>
  41 #endif
  42 #ifdef  CONFIG_IXP425                   /* only valid for IXP425 */
  43 #include <asm/arch/ixp425.h>
  44 #endif
  45 #ifdef CONFIG_LPC2292
  46 #include <asm/arch/hardware.h>
  47 #endif
  48 #if defined(CONFIG_MPC852T) || defined(CONFIG_MPC866)
  49 #include <asm/io.h>
  50 #endif
  51 #include <i2c.h>
  52
  53 /* #define      DEBUG_I2C       */
  54
  55 #ifdef DEBUG_I2C
  56 DECLARE_GLOBAL_DATA_PTR;
  57 #endif
  58
  59 /*-----------------------------------------------------------------------
  60  * Definitions
  61  */
  62
  63 #define RETRIES         0
  64
  65 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
  66 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
  67
  68
  69 #ifdef DEBUG_I2C
  70 #define PRINTD(fmt,args...)     do {    \
  71         if (gd->have_console)           \
  72                 printf (fmt ,##args);   \
  73         } while (0)
  74 #else
  75 #define PRINTD(fmt,args...)
  76 #endif
  77
  78 #if defined(CONFIG_I2C_MULTI_BUS)
  79 static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0;
  80 #endif /* CONFIG_I2C_MULTI_BUS */
  81
  82 /*-----------------------------------------------------------------------
  83  * Local functions
  84  */
  85 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
  86 static void  send_reset (void);
  87 #endif
  88 static void  send_start (void);
  89 static void  send_stop  (void);
  90 static void  send_ack   (int);
  91 static int   write_byte (uchar byte);
  92 static uchar read_byte  (int);
  93
  94 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
  95 /*-----------------------------------------------------------------------
  96  * Send a reset sequence consisting of 9 clocks with the data signal high
  97  * to clock any confused device back into an idle state.  Also send a
  98  * <stop> at the end of the sequence for belts & suspenders.
  99  */
 100 static void send_reset(void)
 101 {
 102         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 103         int j;
 104
 105         I2C_SCL(1);
 106         I2C_SDA(1);
 107 #ifdef  I2C_INIT
 108         I2C_INIT;
 109 #endif
 110         I2C_TRISTATE;
 111         for(j = 0; j < 9; j++) {
 112                 I2C_SCL(0);
 113                 I2C_DELAY;
 114                 I2C_DELAY;
 115                 I2C_SCL(1);
 116                 I2C_DELAY;
 117                 I2C_DELAY;
 118         }
 119         send_stop();
 120         I2C_TRISTATE;
 121 }
 122 #endif
 123
 124 /*-----------------------------------------------------------------------
 125  * START: High -> Low on SDA while SCL is High
 126  */
 127 static void send_start(void)
 128 {
 129         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 130
 131         I2C_DELAY;
 132         I2C_SDA(1);
 133         I2C_ACTIVE;
 134         I2C_DELAY;
 135         I2C_SCL(1);
 136         I2C_DELAY;
 137         I2C_SDA(0);
 138         I2C_DELAY;
 139 }
 140
 141 /*-----------------------------------------------------------------------
 142  * STOP: Low -> High on SDA while SCL is High
 143  */
 144 static void send_stop(void)
 145 {
 146         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 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  * ack should be I2C_ACK or I2C_NOACK
 162  */
 163 static void send_ack(int ack)
 164 {
 165         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 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  * Send 8 bits and look for an acknowledgement.
 181  */
 182 static int write_byte(uchar data)
 183 {
 184         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 185         int j;
 186         int nack;
 187
 188         I2C_ACTIVE;
 189         for(j = 0; j < 8; j++) {
 190                 I2C_SCL(0);
 191                 I2C_DELAY;
 192                 I2C_SDA(data & 0x80);
 193                 I2C_DELAY;
 194                 I2C_SCL(1);
 195                 I2C_DELAY;
 196                 I2C_DELAY;
 197
 198                 data <<= 1;
 199         }
 200
 201         /*
 202          * Look for an <ACK>(negative logic) and return it.
 203          */
 204         I2C_SCL(0);
 205         I2C_DELAY;
 206         I2C_SDA(1);
 207         I2C_TRISTATE;
 208         I2C_DELAY;
 209         I2C_SCL(1);
 210         I2C_DELAY;
 211         I2C_DELAY;
 212         nack = I2C_READ;
 213         I2C_SCL(0);
 214         I2C_DELAY;
 215         I2C_ACTIVE;
 216
 217         return(nack);   /* not a nack is an ack */
 218 }
 219
 220 #if defined(CONFIG_I2C_MULTI_BUS)
 221 /*
 222  * Functions for multiple I2C bus handling
 223  */
 224 unsigned int i2c_get_bus_num(void)
 225 {
 226         return i2c_bus_num;
 227 }
 228
 229 int i2c_set_bus_num(unsigned int bus)
 230 {
 231 #if defined(CONFIG_I2C_MUX)
 232         if (bus < CONFIG_SYS_MAX_I2C_BUS) {
 233                 i2c_bus_num = bus;
 234         } else {
 235                 int     ret;
 236
 237                 ret = i2x_mux_select_mux(bus);
 238                 if (ret == 0)
 239                         i2c_bus_num = bus;
 240                 else
 241                         return ret;
 242         }
 243 #else
 244         if (bus >= CONFIG_SYS_MAX_I2C_BUS)
 245                 return -1;
 246         i2c_bus_num = bus;
 247 #endif
 248         return 0;
 249 }
 250 #endif
 251
 252 /*-----------------------------------------------------------------------
 253  * if ack == I2C_ACK, ACK the byte so can continue reading, else
 254  * send I2C_NOACK to end the read.
 255  */
 256 static uchar read_byte(int ack)
 257 {
 258         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 259         int  data;
 260         int  j;
 261
 262         /*
 263          * Read 8 bits, MSB first.
 264          */
 265         I2C_TRISTATE;
 266         I2C_SDA(1);
 267         data = 0;
 268         for(j = 0; j < 8; j++) {
 269                 I2C_SCL(0);
 270                 I2C_DELAY;
 271                 I2C_SCL(1);
 272                 I2C_DELAY;
 273                 data <<= 1;
 274                 data |= I2C_READ;
 275                 I2C_DELAY;
 276         }
 277         send_ack(ack);
 278
 279         return(data);
 280 }
 281
 282 /*=====================================================================*/
 283 /*                         Public Functions                            */
 284 /*=====================================================================*/
 285
 286 /*-----------------------------------------------------------------------
 287  * Initialization
 288  */
 289 void i2c_init (int speed, int slaveaddr)
 290 {
 291 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
 292         /* call board specific i2c bus reset routine before accessing the   */
 293         /* environment, which might be in a chip on that bus. For details   */
 294         /* about this problem see doc/I2C_Edge_Conditions.                  */
 295         i2c_init_board();
 296 #else
 297         /*
 298          * WARNING: Do NOT save speed in a static variable: if the
 299          * I2C routines are called before RAM is initialized (to read
 300          * the DIMM SPD, for instance), RAM won't be usable and your
 301          * system will crash.
 302          */
 303         send_reset ();
 304 #endif
 305 }
 306
 307 /*-----------------------------------------------------------------------
 308  * Probe to see if a chip is present.  Also good for checking for the
 309  * completion of EEPROM writes since the chip stops responding until
 310  * the write completes (typically 10mSec).
 311  */
 312 int i2c_probe(uchar addr)
 313 {
 314         int rc;
 315
 316         /*
 317          * perform 1 byte write transaction with just address byte
 318          * (fake write)
 319          */
 320         send_start();
 321         rc = write_byte ((addr << 1) | 0);
 322         send_stop();
 323
 324         return (rc ? 1 : 0);
 325 }
 326
 327 /*-----------------------------------------------------------------------
 328  * Read bytes
 329  */
 330 int  i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
 331 {
 332         int shift;
 333         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
 334                 chip, addr, alen, buffer, len);
 335
 336 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
 337         /*
 338          * EEPROM chips that implement "address overflow" are ones
 339          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 340          * address and the extra bits end up in the "chip address"
 341          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 342          * four 256 byte chips.
 343          *
 344          * Note that we consider the length of the address field to
 345          * still be one byte because the extra address bits are
 346          * hidden in the chip address.
 347          */
 348         chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
 349
 350         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
 351                 chip, addr);
 352 #endif
 353
 354         /*
 355          * Do the addressing portion of a write cycle to set the
 356          * chip's address pointer.  If the address length is zero,
 357          * don't do the normal write cycle to set the address pointer,
 358          * there is no address pointer in this chip.
 359          */
 360         send_start();
 361         if(alen > 0) {
 362                 if(write_byte(chip << 1)) {     /* write cycle */
 363                         send_stop();
 364                         PRINTD("i2c_read, no chip responded %02X\n", chip);
 365                         return(1);
 366                 }
 367                 shift = (alen-1) * 8;
 368                 while(alen-- > 0) {
 369                         if(write_byte(addr >> shift)) {
 370                                 PRINTD("i2c_read, address not <ACK>ed\n");
 371                                 return(1);
 372                         }
 373                         shift -= 8;
 374                 }
 375
 376                 /* Some I2C chips need a stop/start sequence here,
 377                  * other chips don't work with a full stop and need
 378                  * only a start.  Default behaviour is to send the
 379                  * stop/start sequence.
 380                  */
 381 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
 382                 send_start();
 383 #else
 384                 send_stop();
 385                 send_start();
 386 #endif
 387         }
 388         /*
 389          * Send the chip address again, this time for a read cycle.
 390          * Then read the data.  On the last byte, we do a NACK instead
 391          * of an ACK(len == 0) to terminate the read.
 392          */
 393         write_byte((chip << 1) | 1);    /* read cycle */
 394         while(len-- > 0) {
 395                 *buffer++ = read_byte(len == 0);
 396         }
 397         send_stop();
 398         return(0);
 399 }
 400
 401 /*-----------------------------------------------------------------------
 402  * Write bytes
 403  */
 404 int  i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
 405 {
 406         int shift, failures = 0;
 407
 408         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
 409                 chip, addr, alen, buffer, len);
 410
 411         send_start();
 412         if(write_byte(chip << 1)) {     /* write cycle */
 413                 send_stop();
 414                 PRINTD("i2c_write, no chip responded %02X\n", chip);
 415                 return(1);
 416         }
 417         shift = (alen-1) * 8;
 418         while(alen-- > 0) {
 419                 if(write_byte(addr >> shift)) {
 420                         PRINTD("i2c_write, address not <ACK>ed\n");
 421                         return(1);
 422                 }
 423                 shift -= 8;
 424         }
 425
 426         while(len-- > 0) {
 427                 if(write_byte(*buffer++)) {
 428                         failures++;
 429                 }
 430         }
 431         send_stop();
 432         return(failures);
 433 }