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 #if defined(CONFIG_AT91FAMILY)
  34 #include <asm/io.h>
  35 #include <asm/arch/hardware.h>
  36 #include <asm/arch/at91_pio.h>
  37 #ifdef CONFIG_AT91_LEGACY
  38 #include <asm/arch/gpio.h>
  39 #endif
  40 #endif
  41 #ifdef  CONFIG_IXP425                   /* only valid for IXP425 */
  42 #include <asm/arch/ixp425.h>
  43 #endif
  44 #ifdef CONFIG_LPC2292
  45 #include <asm/arch/hardware.h>
  46 #endif
  47 #if defined(CONFIG_MPC852T) || defined(CONFIG_MPC866)
  48 #include <asm/io.h>
  49 #endif
  50 #include <i2c.h>
  51
  52 #if defined(CONFIG_SOFT_I2C_GPIO_SCL)
  53 # include <asm/gpio.h>
  54
  55 # ifndef I2C_GPIO_SYNC
  56 #  define I2C_GPIO_SYNC
  57 # endif
  58
  59 # ifndef I2C_INIT
  60 #  define I2C_INIT \
  61         do { \
  62                 gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
  63                 gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
  64         } while (0)
  65 # endif
  66
  67 # ifndef I2C_ACTIVE
  68 #  define I2C_ACTIVE do { } while (0)
  69 # endif
  70
  71 # ifndef I2C_TRISTATE
  72 #  define I2C_TRISTATE do { } while (0)
  73 # endif
  74
  75 # ifndef I2C_READ
  76 #  define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
  77 # endif
  78
  79 # ifndef I2C_SDA
  80 #  define I2C_SDA(bit) \
  81         do { \
  82                 if (bit) \
  83                         gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
  84                 else \
  85                         gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
  86                 I2C_GPIO_SYNC; \
  87         } while (0)
  88 # endif
  89
  90 # ifndef I2C_SCL
  91 #  define I2C_SCL(bit) \
  92         do { \
  93                 gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
  94                 I2C_GPIO_SYNC; \
  95         } while (0)
  96 # endif
  97
  98 # ifndef I2C_DELAY
  99 #  define I2C_DELAY udelay(5)   /* 1/4 I2C clock duration */
 100 # endif
 101
 102 #endif
 103
 104 /* #define      DEBUG_I2C       */
 105
 106 #ifdef DEBUG_I2C
 107 DECLARE_GLOBAL_DATA_PTR;
 108 #endif
 109
 110 /*-----------------------------------------------------------------------
 111  * Definitions
 112  */
 113
 114 #define RETRIES         0
 115
 116 #define I2C_ACK         0               /* PD_SDA level to ack a byte */
 117 #define I2C_NOACK       1               /* PD_SDA level to noack a byte */
 118
 119
 120 #ifdef DEBUG_I2C
 121 #define PRINTD(fmt,args...)     do {    \
 122         if (gd->have_console)           \
 123                 printf (fmt ,##args);   \
 124         } while (0)
 125 #else
 126 #define PRINTD(fmt,args...)
 127 #endif
 128
 129 #if defined(CONFIG_I2C_MULTI_BUS)
 130 static unsigned int i2c_bus_num __attribute__ ((section (".data"))) = 0;
 131 #endif /* CONFIG_I2C_MULTI_BUS */
 132
 133 /*-----------------------------------------------------------------------
 134  * Local functions
 135  */
 136 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 137 static void  send_reset (void);
 138 #endif
 139 static void  send_start (void);
 140 static void  send_stop  (void);
 141 static void  send_ack   (int);
 142 static int   write_byte (uchar byte);
 143 static uchar read_byte  (int);
 144
 145 #if !defined(CONFIG_SYS_I2C_INIT_BOARD)
 146 /*-----------------------------------------------------------------------
 147  * Send a reset sequence consisting of 9 clocks with the data signal high
 148  * to clock any confused device back into an idle state.  Also send a
 149  * <stop> at the end of the sequence for belts & suspenders.
 150  */
 151 static void send_reset(void)
 152 {
 153         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 154         int j;
 155
 156         I2C_SCL(1);
 157         I2C_SDA(1);
 158 #ifdef  I2C_INIT
 159         I2C_INIT;
 160 #endif
 161         I2C_TRISTATE;
 162         for(j = 0; j < 9; j++) {
 163                 I2C_SCL(0);
 164                 I2C_DELAY;
 165                 I2C_DELAY;
 166                 I2C_SCL(1);
 167                 I2C_DELAY;
 168                 I2C_DELAY;
 169         }
 170         send_stop();
 171         I2C_TRISTATE;
 172 }
 173 #endif
 174
 175 /*-----------------------------------------------------------------------
 176  * START: High -> Low on SDA while SCL is High
 177  */
 178 static void send_start(void)
 179 {
 180         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 181
 182         I2C_DELAY;
 183         I2C_SDA(1);
 184         I2C_ACTIVE;
 185         I2C_DELAY;
 186         I2C_SCL(1);
 187         I2C_DELAY;
 188         I2C_SDA(0);
 189         I2C_DELAY;
 190 }
 191
 192 /*-----------------------------------------------------------------------
 193  * STOP: Low -> High on SDA while SCL is High
 194  */
 195 static void send_stop(void)
 196 {
 197         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 198
 199         I2C_SCL(0);
 200         I2C_DELAY;
 201         I2C_SDA(0);
 202         I2C_ACTIVE;
 203         I2C_DELAY;
 204         I2C_SCL(1);
 205         I2C_DELAY;
 206         I2C_SDA(1);
 207         I2C_DELAY;
 208         I2C_TRISTATE;
 209 }
 210
 211 /*-----------------------------------------------------------------------
 212  * ack should be I2C_ACK or I2C_NOACK
 213  */
 214 static void send_ack(int ack)
 215 {
 216         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 217
 218         I2C_SCL(0);
 219         I2C_DELAY;
 220         I2C_ACTIVE;
 221         I2C_SDA(ack);
 222         I2C_DELAY;
 223         I2C_SCL(1);
 224         I2C_DELAY;
 225         I2C_DELAY;
 226         I2C_SCL(0);
 227         I2C_DELAY;
 228 }
 229
 230 /*-----------------------------------------------------------------------
 231  * Send 8 bits and look for an acknowledgement.
 232  */
 233 static int write_byte(uchar data)
 234 {
 235         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 236         int j;
 237         int nack;
 238
 239         I2C_ACTIVE;
 240         for(j = 0; j < 8; j++) {
 241                 I2C_SCL(0);
 242                 I2C_DELAY;
 243                 I2C_SDA(data & 0x80);
 244                 I2C_DELAY;
 245                 I2C_SCL(1);
 246                 I2C_DELAY;
 247                 I2C_DELAY;
 248
 249                 data <<= 1;
 250         }
 251
 252         /*
 253          * Look for an <ACK>(negative logic) and return it.
 254          */
 255         I2C_SCL(0);
 256         I2C_DELAY;
 257         I2C_SDA(1);
 258         I2C_TRISTATE;
 259         I2C_DELAY;
 260         I2C_SCL(1);
 261         I2C_DELAY;
 262         I2C_DELAY;
 263         nack = I2C_READ;
 264         I2C_SCL(0);
 265         I2C_DELAY;
 266         I2C_ACTIVE;
 267
 268         return(nack);   /* not a nack is an ack */
 269 }
 270
 271 #if defined(CONFIG_I2C_MULTI_BUS)
 272 /*
 273  * Functions for multiple I2C bus handling
 274  */
 275 unsigned int i2c_get_bus_num(void)
 276 {
 277         return i2c_bus_num;
 278 }
 279
 280 int i2c_set_bus_num(unsigned int bus)
 281 {
 282 #if defined(CONFIG_I2C_MUX)
 283         if (bus < CONFIG_SYS_MAX_I2C_BUS) {
 284                 i2c_bus_num = bus;
 285         } else {
 286                 int     ret;
 287
 288                 ret = i2x_mux_select_mux(bus);
 289                 i2c_init_board();
 290                 if (ret == 0)
 291                         i2c_bus_num = bus;
 292                 else
 293                         return ret;
 294         }
 295 #else
 296         if (bus >= CONFIG_SYS_MAX_I2C_BUS)
 297                 return -1;
 298         i2c_bus_num = bus;
 299 #endif
 300         return 0;
 301 }
 302 #endif
 303
 304 /*-----------------------------------------------------------------------
 305  * if ack == I2C_ACK, ACK the byte so can continue reading, else
 306  * send I2C_NOACK to end the read.
 307  */
 308 static uchar read_byte(int ack)
 309 {
 310         I2C_SOFT_DECLARATIONS   /* intentional without ';' */
 311         int  data;
 312         int  j;
 313
 314         /*
 315          * Read 8 bits, MSB first.
 316          */
 317         I2C_TRISTATE;
 318         I2C_SDA(1);
 319         data = 0;
 320         for(j = 0; j < 8; j++) {
 321                 I2C_SCL(0);
 322                 I2C_DELAY;
 323                 I2C_SCL(1);
 324                 I2C_DELAY;
 325                 data <<= 1;
 326                 data |= I2C_READ;
 327                 I2C_DELAY;
 328         }
 329         send_ack(ack);
 330
 331         return(data);
 332 }
 333
 334 /*=====================================================================*/
 335 /*                         Public Functions                            */
 336 /*=====================================================================*/
 337
 338 /*-----------------------------------------------------------------------
 339  * Initialization
 340  */
 341 void i2c_init (int speed, int slaveaddr)
 342 {
 343 #if defined(CONFIG_SYS_I2C_INIT_BOARD)
 344         /* call board specific i2c bus reset routine before accessing the   */
 345         /* environment, which might be in a chip on that bus. For details   */
 346         /* about this problem see doc/I2C_Edge_Conditions.                  */
 347         i2c_init_board();
 348 #else
 349         /*
 350          * WARNING: Do NOT save speed in a static variable: if the
 351          * I2C routines are called before RAM is initialized (to read
 352          * the DIMM SPD, for instance), RAM won't be usable and your
 353          * system will crash.
 354          */
 355         send_reset ();
 356 #endif
 357 }
 358
 359 /*-----------------------------------------------------------------------
 360  * Probe to see if a chip is present.  Also good for checking for the
 361  * completion of EEPROM writes since the chip stops responding until
 362  * the write completes (typically 10mSec).
 363  */
 364 int i2c_probe(uchar addr)
 365 {
 366         int rc;
 367
 368         /*
 369          * perform 1 byte write transaction with just address byte
 370          * (fake write)
 371          */
 372         send_start();
 373         rc = write_byte ((addr << 1) | 0);
 374         send_stop();
 375
 376         return (rc ? 1 : 0);
 377 }
 378
 379 /*-----------------------------------------------------------------------
 380  * Read bytes
 381  */
 382 int  i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
 383 {
 384         int shift;
 385         PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
 386                 chip, addr, alen, buffer, len);
 387
 388 #ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
 389         /*
 390          * EEPROM chips that implement "address overflow" are ones
 391          * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
 392          * address and the extra bits end up in the "chip address"
 393          * bit slots. This makes a 24WC08 (1Kbyte) chip look like
 394          * four 256 byte chips.
 395          *
 396          * Note that we consider the length of the address field to
 397          * still be one byte because the extra address bits are
 398          * hidden in the chip address.
 399          */
 400         chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
 401
 402         PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
 403                 chip, addr);
 404 #endif
 405
 406         /*
 407          * Do the addressing portion of a write cycle to set the
 408          * chip's address pointer.  If the address length is zero,
 409          * don't do the normal write cycle to set the address pointer,
 410          * there is no address pointer in this chip.
 411          */
 412         send_start();
 413         if(alen > 0) {
 414                 if(write_byte(chip << 1)) {     /* write cycle */
 415                         send_stop();
 416                         PRINTD("i2c_read, no chip responded %02X\n", chip);
 417                         return(1);
 418                 }
 419                 shift = (alen-1) * 8;
 420                 while(alen-- > 0) {
 421                         if(write_byte(addr >> shift)) {
 422                                 PRINTD("i2c_read, address not <ACK>ed\n");
 423                                 return(1);
 424                         }
 425                         shift -= 8;
 426                 }
 427
 428                 /* Some I2C chips need a stop/start sequence here,
 429                  * other chips don't work with a full stop and need
 430                  * only a start.  Default behaviour is to send the
 431                  * stop/start sequence.
 432                  */
 433 #ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
 434                 send_start();
 435 #else
 436                 send_stop();
 437                 send_start();
 438 #endif
 439         }
 440         /*
 441          * Send the chip address again, this time for a read cycle.
 442          * Then read the data.  On the last byte, we do a NACK instead
 443          * of an ACK(len == 0) to terminate the read.
 444          */
 445         write_byte((chip << 1) | 1);    /* read cycle */
 446         while(len-- > 0) {
 447                 *buffer++ = read_byte(len == 0);
 448         }
 449         send_stop();
 450         return(0);
 451 }
 452
 453 /*-----------------------------------------------------------------------
 454  * Write bytes
 455  */
 456 int  i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
 457 {
 458         int shift, failures = 0;
 459
 460         PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
 461                 chip, addr, alen, buffer, len);
 462
 463         send_start();
 464         if(write_byte(chip << 1)) {     /* write cycle */
 465                 send_stop();
 466                 PRINTD("i2c_write, no chip responded %02X\n", chip);
 467                 return(1);
 468         }
 469         shift = (alen-1) * 8;
 470         while(alen-- > 0) {
 471                 if(write_byte(addr >> shift)) {
 472                         PRINTD("i2c_write, address not <ACK>ed\n");
 473                         return(1);
 474                 }
 475                 shift -= 8;
 476         }
 477
 478         while(len-- > 0) {
 479                 if(write_byte(*buffer++)) {
 480                         failures++;
 481                 }
 482         }
 483         send_stop();
 484         return(failures);
 485 }